Absolute Pitch: Evidence for Early Cognitive Facilitation during Passive Listening as Revealed by Reduced P3a Amplitudes

Absolute pitch (AP) is the rare ability to identify or produce different pitches without using reference tones. At least two sequential processing stages are assumed to contribute to this phenomenon. The first recruits a pitch memory mechanism at an early stage of auditory processing, whereas the second is driven by a later cognitive mechanism (pitch labeling). Several investigations have used active tasks, but it is unclear how these two mechanisms contribute to AP during passive listening. The present work investigated the temporal dynamics of tone processing in AP and non-AP (NAP) participants by using EEG. We applied a passive oddball paradigm with between- and within-tone category manipulations and analyzed the MMN reflecting the early stage of auditory processing and the P3a response reflecting the later cognitive mechanism during the second processing stage. Results did not reveal between-group differences in MMN waveforms. By contrast, the P3a response was specifically associated with AP and sensitive to the processing of different pitch types. Specifically, AP participants exhibited smaller P3a amplitudes, especially in between-tone category conditions, and P3a responses correlated significantly with the age of commencement of musical training, suggesting an influence of early musical exposure on AP. Our results reinforce the current opinion that the representation of pitches at the processing level of the auditory-related cortex is comparable among AP and NAP participants, whereas the later processing stage is critical for AP. Results are interpreted as reflecting cognitive facilitation in AP participants, possibly driven by the availability of multiple codes for tones.

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title: Absolute pitch.
abstract: Absolute pitch (AP) is the ability to identify a tone's pitch or to produce a tone at a particular pitch without the use of an external reference pitch. AP exists in varying degrees among people generally described as AP possessors. AP possessors vary not only in the accuracy with which they can identify pitches but also in their ability to produce pitches absolutely and in their ability to identify tones of various timbers and in various pitch registers. AP possessors' memory for pitches is mediated by verbal pitch names; they do not have superior memory for pitches per se. Although the etiology of AP is not yet completely understood, evidence points toward the early-learning theory. This theory states that AP can be learned by anyone during a limited period early in development, up to about age 6, after which a general developmental shift from perceiving individual features to perceiving relations among features makes AP difficult or impossible to acquire.

title: Absolute pitch: perception, coding, and controversies
abstract: Recent findings in cognitive neuroscience and cognitive psychology are converging to shed light on the nature of processing, categorization and memory for pitch in humans and animals. Although most people are unable to name or place pitch values in consistent, well-defined categories, as they do for color, stable long-term memory for pitch has been shown in certain animal species, in infants, and in both adult musicians and non-musicians. 'Absolute pitch', the rare ability to label pitches without external reference, appears to require acquisition early in life, and involves specialized brain mechanisms, now partially identified. Research on pitch coding strategies informs wider theories in cognitive science of semantic memory, and the nature of perceptual categories.

title: Absolute pitch: a model for understanding the influence of genes and development on neural and cognitive function
abstract: Absolute pitch (AP), the ability to identify or produce the pitch of a sound without any reference point, is discussed here as a possible model system for understanding the neurobiology of complex cognitive functions. AP is of interest because it may reflect an atypical organization of sensory representations. Indications are that it depends on both genetic factors and exposure to musical training during childhood, supporting the idea of a sensitive period. Functional and structural neuroimaging studies suggest special roles for working memory and associative memory mechanisms in AP, and results from these studies indicate that there may be structural markers of AP in asymmetries of cortical areas. AP seems to depend on the nervous system's response to experiential, maturational and genetic factors, making it a good candidate model for understanding how these interactions play out in cognitive development generally.

title: Measurement of Absolute Pitch
abstract: The unusual ability of certain individuals to place the pitch of any given note in isolation was introduced to psychology by Stumpf (1883). The "placing of a note" may be demonstrated in two ways: (a) by Recognition-identifying the note by its frequency or musical name; and (b} by Recall-adjusting a variable frequency (e.g. sung/whistled/hummed) to a level satisfactorily similar to a note specified. Himself a musician, Stumpf argued the dependence of absolute pitch (A.P.) on a memory tone, an internal standard to which the note for recognition or recall may be related. Some violinists, for example, claim an unusually accurate memory for the note A from which their instrument is tuned; while pianists may demonstrate a similar inclination towards middle C. And claimants to A.P. today often reveal, by a good deal of hesitation and humming, that the accuracy of their recognition and recall is dependent on relative judgments in precisely this way.

title: Absolute pitch among students at the Shanghai Conservatory of Music: a large-scale direct-test study.
abstract: This paper reports a large-scale direct-test study of absolute pitch (AP) in students at the Shanghai Conservatory of Music. Overall note-naming scores were very high, with high scores correlating positively with early onset of musical training. Students who had begun training at age ≤5 yr scored 83% correct not allowing for semitone errors and 90% correct allowing for semitone errors. Performance levels were higher for white key pitches than for black key pitches. This effect was greater for orchestral performers than for pianists, indicating that it cannot be attributed to early training on the piano. Rather, accuracy in identifying notes of different names (C, C#, D, etc.) correlated with their frequency of occurrence in a large sample of music taken from the Western tonal repertoire. There was also an effect of pitch range, so that performance on tones in the two-octave range beginning on Middle C was higher than on tones in the octave below Middle C. In addition, semitone errors tended to be on the sharp side. The evidence also ran counter to the hypothesis, previously advanced by others, that the note A plays a special role in pitch identification judgments.

title: Absolute pitch among students in an American music conservatory: association with tone language fluency.
abstract: Absolute pitch (AP), the ability to name a musical note in the absence of a reference note, is extremely rare in the U.S. and Europe, and its genesis is unclear. The prevalence of AP was examined among students in an American music conservatory as a function of age of onset of musical training, ethnicity, and fluency in speaking a tone language. Taking those of East Asian ethnicity, the performance level on a test of AP was significantly higher among those who spoke a tone language very fluently compared with those who spoke a tone language fairly fluently and also compared with those who were not fluent in speaking a tone language. The performance level of this last group did not differ significantly from that of Caucasian students who spoke only nontone language. Early onset of musical training was associated with enhanced performance, but this did not interact with the effect of language. Further analyses showed that the results could not be explained by country of early music education. The findings support the hypothesis that the acquisition of AP by tone language speakers involves the same process as occurs in the acquisition of a second tone language.

title: Absolute pitch among American and Chinese conservatory students: prevalence differences, and evidence for a speech-related critical period.
abstract: Absolute pitch is extremely rare in the U.S. and Europe; this rarity has so far been unexplained. This paper reports a substantial difference in the prevalence of absolute pitch in two normal populations, in a large-scale study employing an on-site test, without self-selection from within the target populations. Music conservatory students in the U.S. and China were tested. The Chinese subjects spoke the tone language Mandarin, in which pitch is involved in conveying the meaning of words. The American subjects were nontone language speakers. The earlier the age of onset of musical training, the greater the prevalence of absolute pitch; however, its prevalence was far greater among the Chinese than the U.S. students for each level of age of onset of musical training. The findings suggest that the potential for acquiring absolute pitch may be universal, and may be realized by enabling infants to associate pitches with verbal labels during the critical period for acquisition of features of their native language.

title: Speech Patterns Heard Early in Life Influence Later Perception of the Tritone Paradox
abstract: The tritone paradox occurs when two tones that are related by a half-octave (or tritone) are presented in succession and the tones are constructed in such a way that their pitch classes (C, C♯♯, D, etc.) are clearly defined but their octave placement is ambiguous. Previous studies have shown that there are large individual differences in how such tone pairs are perceived, and these differences correlate with the listener9s language or dialect. We here present findings showing that perception of the tritone paradox can be heavily influenced by speech heard early in life, even for listeners who do not speak their first language fluently. Our findings point to a specific linkage between speech and music, and they also shed light on the issue of critical periods for the acquisition of intonational properties of speech.

title: Absolute pitch in a four-year-old boy with autism.
abstract: Absolute pitch is the ability to identify the pitch of an isolated tone. We report on a 4-year-old boy with autism and absolute pitch, one of the youngest reported in the literature. Absolute pitch is thought to be attributable to a single gene, transmitted in an autosomal-dominant fashion. The association of absolute pitch with autism raises the speculation that this talent could be linked to a genetically distinct subset of children with autism. Further, the identification of absolute pitch in even young children with autism may lead to a lifelong skill.

title: Absolute Pitch in Williams Syndrome
abstract: Absolute pitch is reported to occur in 1 out of 10,000 persons, usually those trained in music before age 6. We demonstrate that the five individuals we tested, who have Williams syndrome, a condition caused
 by a microdeletion of about 20 genes in the q11.23 region of one of their two chromosomes number seven, possess near ceiling levels of absolute pitch despite their limited cognitive abilities. With these
 individuals, we also describe our preliminary findings on relative pitch, transposition, and retention. We discuss the possibilities that (1) the incidence of absolute pitch among individuals with Williams
 syndrome is higher than that found in the general population and (2) the normal early childhood critical period of absolute pitch acquisition may be extended in individuals with Williams syndrome.

title: Absolute pitch in infant auditory learning: evidence for developmental reorganization.
abstract: To what extent do infants represent the absolute pitches of complex auditory stimuli? Two experiments with 8-month-old infants examined the use of absolute and relative pitch cues in a tone-sequence statistical learning task. The results suggest that, given unsegmented stimuli that do not conform to the rules of musical composition, infants are more likely to track patterns of absolute pitches than of relative pitches. A 3rd experiment tested adults with or without musical training on the same statistical learning tasks used in the infant experiments. Unlike the infants, adult listeners relied primarily on relative pitch cues. These results suggest a shift from an initial focus on absolute pitch to the eventual dominance of relative pitch, which, it is argued, is more useful for both music and speech processing.

title: The evolution of the music faculty: a comparative perspective
abstract: We propose a theoretical framework for exploring the evolution of the music faculty from a comparative perspective. This framework addresses questions of phylogeny, adaptive function, innate biases and perceptual mechanisms. We argue that comparative studies can make two unique contributions to investigations of the origins of music. First, musical exposure can be controlled and manipulated to an extent not possible in humans. Second, any features of music perception found in nonhuman animals must not be part of an adaptation for music, and must rather be side effects of more general features of perception or cognition. We review studies that use animal research to target specific aspects of music perception (such as octave generalization), as well as studies that investigate more general and shared systems of the mind/brain that may be relevant to music (such as rhythm perception and emotional encoding). Finally, we suggest several directions for future work, following the lead of comparative studies on the language faculty.

title: Genome-wide study of families with absolute pitch reveals linkage to 8q24.21 and locus heterogeneity.
abstract: Absolute pitch (AP) is the rare ability to instantaneously recognize and label tones with their musical note names without using a reference pitch for comparison. The etiology of AP is complex. Prior studies have implicated both genetic and environmental factors in its genesis, yet the molecular basis for AP remains unknown. To locate regions of the human genome that may harbor AP-predisposing genetic variants, we performed a genome-wide linkage study on 73 multiplex AP families by genotyping them with 6090 SNP markers. Nonparametric multipoint linkage analyses were conducted, and the strongest evidence for linkage was observed on chromosome 8q24.21 in the subset of 45 families with European ancestry (exponential LOD score = 3.464, empirical genome-wide p = 0.03). Other regions with suggestive LOD scores included chromosomes 7q22.3, 8q21.11, and 9p21.3. Of these four regions, only the 7q22.3 linkage peak was also evident when 19 families with East Asian ancestry were analyzed separately. Though only one of these regions has yet reached statistical significance individually, we detected a larger number of independent linkage peaks than expected by chance overall, indicating that AP is genetically heterogeneous.

title: Dichotomy and perceptual distortions in absolute pitch ability
abstract: Absolute pitch (AP) is the rare ability to identify the pitch of a tone without the aid of a reference tone. Understanding both the nature and genesis of AP can provide insights into neuroplasticity in the auditory system. We explored factors that may influence the accuracy of pitch perception in AP subjects both during the development of the trait and in later age. We used a Web-based survey and a pitch-labeling test to collect perceptual data from 2,213 individuals, 981 (44%) of whom proved to have extraordinary pitch-naming ability. The bimodal distribution in pitch-naming ability signifies AP as a distinct perceptual trait, with possible implications for its genetic basis. The wealth of these data has allowed us to uncover unsuspected note-naming irregularities suggestive of a “perceptual magnet” centered at the note “A.” In addition, we document a gradual decline in pitch-naming accuracy with age, characterized by a perceptual shift in the “sharp” direction. These findings speak both to the process of acquisition of AP and to its stability.

title: Familial aggregation of absolute pitch.
abstract: Absolute pitch (AP) is a behavioral trait that is defined as the ability to identify the pitch of tones in the absence of a reference pitch. AP is an ideal phenotype for investigation of gene and environment interactions in the development of complex human behaviors. Individuals who score exceptionally well on formalized auditory tests of pitch perception are designated as "AP-1." As described in this report, auditory testing of siblings of AP-1 probands and of a control sample indicates that AP-1 aggregates in families. The implications of this finding for the mapping of loci for AP-1 predisposition are discussed.

title: Absolute pitch: an approach for identification of genetic and nongenetic components.
abstract: Absolute pitch (AP) is the ability to recognize a pitch, without an external reference. By surveying more than 600 musicians in music conservatories, training programs, and orchestras, we have attempted to dissect the influences of early musical training and genetics on the development of this ability. Early musical training appears to be necessary but not sufficient for the development of AP. Forty percent of musicians who had begun training at <=4 years of age reported AP, whereas only 3% of those who had initiated training at >=9 years of age did so. Self-reported AP possessors were four times more likely to report another AP possessor in their families than were non-AP possessors. These data suggest that both early musical training and genetic predisposition are needed for the development of AP. We developed a simple computer-based acoustical test that has allowed us to subdivide AP possessors into distinct groups, on the basis of their performance. Investigation of individuals who performed extremely well on this test has already led us to identify several families that will be suitable for studies of the genetic basis of AP.

title: Absolute Pitch, Speech, and Tone Language: Some Experiments and a Proposed Framework
abstract: Absolute pitch is generally considered to reflect a rare musical endowment; however, its characteristics are puzzling and its genesis is unclear. We describe two experiments in which native speakers of tone languages——Mandarin and Vietnamese——were found to display a remarkably precise and stable form of absolute pitch in enunciating words. We further describe a third experiment in which speakers of English displayed less stability on an analogous task. Based on these findings, and considering the related literatures on critical periods in speech development, and the neurological underpinnings of lexical tone, we propose a framework for the genesis of absolute pitch. The framework assumes that absolute pitch originally evolved as a feature of speech, analogous to other features such as vowel quality, and that speakers of tone language naturally acquire this feature during the critical period for speech acquisition. We further propose that the acquisition of absolute pitch by rare individuals who speak an intonation language may be associated with a critical period of unusually long duration, so that it encompasses the age at which the child can take music lessons. We conclude that the potential to acquire absolute pitch is universally present at birth, and that it can be realized by enabling the infant to associate pitches with verbal labels during the critical period for speech acquisition.

title: Early childhood music education and predisposition to absolute pitch: teasing apart genes and environment.
abstract: Twelve years ago in this journal, Pro®ta and Bidder [1988] reported the ®rst evidence for familial aggregation of a rare cognitive phenotype known commonly as ``perfect pitch'', also designated ``absolute pitch.'' Since that report, several studies [Baharloo et al., 1998; Gregersen et al., 1999] provided evidence for genetic and environmental effects in predisposing to the development of absolute pitch (AP). Absolute pitch is a relatively uncommon cognitive ability possessed by a minority of professional and amateur musicians, characterized by their ability to identify pitch names, or to recall speci®c pitches, without bene®t of a reference pitch; this is usually accomplished in a relatively effortless and instantaneous fashion [Ward and Burns, 1982; Gregersen, 1998]. The prevalence of AP in the general population is unknown because it cannot be ascertained in subjects unless they possess at least a minimum amount of musical education. The prevalence of AP in populations of students in professional level music schools or in the personnel of major orchestras is in the range of 10±15% [Baharloo et al., 1998; Gregersen et al., 1999]. This is in contrast to the prevalence estimate of 1/1,500 in amateur music students reported previously [Pro®ta and Bidder, 1988]. A history of formal musical training before age 7 is widely acknowledged to predispose to AP; however, such training is neither necessary nor suf®cient in most persons. As noted above, substantial familial aggregation of AP occurs, although it is unclear to what degree this re ̄ects genetic factors [Baharloo et al., 1998; Gregersen et al., 1999]. We report the results of a survey of 1067 music students who were enrolled in music theory classes in one of 13 educational institutions in the United States. In addition to questions concerning AP ability and family history, we attempted to establish the nature of the musical training that these students received before the age of 7. Some types of early childhood education are designed with the express purpose of developing AP ability. These include the Yamaha method, the Royal College method, and other methods termed ``®xed do.'' ``Fixed do'' pedagogy expressly associates solfeÂge syllables (do-re-mi, etc.) with particular standard pitches: for example ``do'' is always C, ``sol'' is always G. Other types of training are more geared to the development of overall musicality, and emphasize the development of relative pitch ability, with minimal if any attempt to train for absolute pitch recognition. These include the Suzuki method, and other ``moveable do'' techniques. ``Moveable do'' pedagogy associates solfeÂge syllables with a scalar function within a key, so that ``do'' can associate with different pitches, depending on the key being utilized for the training exercise. Instrumental music lessons generally place no emphasis on absolute pitch ability, and we did not categorize them as part of ``®xed do'' pedagogy, although of course, practice on most instruments does reinforce the association of particular note names with speci®c pitches. We also asked about other forms of exposure to music, such as the presence of a parent or sib who either studied or taught music in the home. Respondents were speci®cally asked to indicate which of these types of exposure to music they had received before the age of 7. The overall rate of AP in this population was 12.2%. Similar to results we reported previously [Gregersen et al., 1999], there was a markedly increased rate of AP among Asian students (42/80; 47.5%) compared with Caucasian students (75/834; 9.0%). The relatively higher rate in Asians was present among all the major ethnic subgroups Japanese (26% AP), Korean (37% AP) and Chinese (65% AP). One possible explanation for this difference might be that early childhood music exposure is more frequent in Asian students. There was no signi®cant difference, however, between these two ethnic groups, with 80% of Asians and 71% of Caucasians reporting early music exposure of at least some type (P0.09). When the type of early childhood music training was compared, however, Asians were signi®cantly more likely to have been exposed to early training based on ``®xed do'' techniques compared with Caucasians (29% vs. 6.0%, P0.001). We also performed a logistic regression using different types of early childhood music training among *Correspondence to: Peter K. Gregersen, M.D., Division of Biology and Human Genetics, North Shore University Hospital, 350 Community Drive, Manhasset, NY 11030.

title: Learning the ““Special Note””: Evidence for a Critical Period for Absolute Pitch Acquisition
abstract: Children (3––6 years old) and adults were trained for 6 weeks to identify a single tone, C 5 . Test sessions, held at the end of each week, had participants identify C 5 within a set of seven alternative tones. By the third week of training, identification accuracy of children 5––6 years old surpassed the accuracies of children 3––4 years old and adults. Combined with an analysis of perceptual strategies, the data provide strong support for a critical period for absolute pitch acquisition. Received July 12, 2003, accepted August 1,2003

title: Musical pitch identification by absolute pitch possessors
abstract: Musical pitch identification was investigated in two experiments in which absolute pitch (AP) possessors and nonpossessors categorized tones presented in isolation into predetermined pitch classes. Stimuli consisted of 60 different tones per octave (at intervals of 20 cents). The experiments were designed to minimize the possibility that subjects could use strategies other than AP in performing the task. The results clearly differentiated AP possessors from nonpossessors in accuracy and speed of responding. Those subjects who had AP could categorize the tones quite consistently by using musical qualities of the tones (tone chroma). However, they did not respond uniformly to all stimuli; they responded more accurately and quickly to some musically important tones in a C-major mode (C, E, or G).On the other hand, those who had no AP showed almost random response patterns. In the absence of a tonal context, they could not use tone chroma, but onlytone height. It is argued that tone chroma should be defined as the musical characteristics of tones in a tonal context, and that AP possessors are unique in that they can perceive it absolutely in the absence of any musical context. Although AP was believed to be very rare, it was proved here that a phenomenally large proportion of the subjects tested had AP. The correlation was observed between AP possession and early musical training that started at the age of 3 to 5.

title: Long‐term exposure to music enhances the sensitivity of the auditory system in children
abstract: This event‐related brain potential study aims to contribute to the present debate regarding the effect of musical training on the maturation of the human auditory nervous system. To address this issue, we recorded the mismatch negativity (MMN) evoked by violin and pure sine‐wave tones in a group of 7.5‐ to 12‐year‐old children who had either several years of musical experience with Suzuki violin lessons, or no musical training. The strength of the MMN responses to violin tones evident in the Suzuki students clearly surpassed responses in controls; the reverse pattern was observed for sine‐wave tones. Suzuki students showed significantly shorter MMN latencies to violin tones than to pure tones; the MMN latency did not differ significantly between pure tones and violin sounds in the control group. Thus, our data provide general evidence of how and to what extent extensive musical experience affects the maturation of human auditory function at multiple levels, namely, accuracy and speed of auditory discrimination processing. Our findings add to the present understanding of neuroplastic organization and function of the mammalian nervous system. Furthermore, behavioural recordings obtained from the participating children provide corroborating evidence for a relationship between the duration and intensity of training, the specific sensitivity to instrumental timbre, and pitch recognition abilities.

title: Auditory stroop and absolute pitch: An fMRI study
abstract: To date, the underlying cognitive and neural mechanisms of absolute pitch (AP) have remained elusive. In the present fMRI study, we investigated verbal and tonal perception and working memory in musicians with and without absolute pitch. Stimuli were sine wave tones and syllables (names of the scale tones) presented simultaneously. Participants listened to sequences of five stimuli, and then rehearsed internally either the syllables or the tones. Finally participants indicated whether a test stimulus had been presented during the sequence. For an auditory stroop task, half of the tonal sequences were congruent (frequencies of tones corresponded to syllables which were the names of the scale tones) and half were incongruent (frequencies of tones did not correspond to syllables). Results indicate that first, verbal and tonal perception overlap strongly in the left superior temporal gyrus/sulcus (STG/STS) in AP musicians only. Second, AP is associated with the categorical perception of tones. Third, the left STG/STS is activated in AP musicians only for the detection of verbal‐tonal incongruencies in the auditory stroop task. Finally, verbal labelling of tones in AP musicians seems to be automatic. Overall, a unique feature of AP appears to be the similarity between verbal and tonal perception.

title: Absolute memory for musical pitch: Evidence from the production of learned melodies
abstract: Evidence for the absolute nature of long-term auditory memory is provided by analyzing the production of familiar melodies. Additionally, a two-component theory of absolute pitch is presented, in which this rare ability is conceived as consisting of a more common ability,pitch memory, and a separate, less common ability,pitch labeling. Forty-six subjects sang two different popular songs, and their productions were compared with the actual pitches used in recordings of those songs. Forty percent of the subjects sang the correct pitch on at least one trial; 12% of the subjects hit the correct pitch on both trials, and 44% came within two semitones of the correct pitch on both trials. The results show a convergence with previous studies on the stability of auditory imagery and latent absolute pitch ability; the results further suggest that individuals might possess representations of pitch that are more stable and accurate than previously recognized.

title: The tritone paradox: Effects of spectral variables
abstract: A paradoxical two-tone pattern is explored, which is heard as ascending when played in one key but as descending when played in a different key. The pattern thus provides a striking counterexample to the principle of invariance under transposition. In addition, the pattern in any one key is heard as ascending by some listeners but as descending by others. This study examines the effects of spectral variables on how the pattern is perceived.

title: Multiple coding strategies in the retention of musical tones by possessors of absolute pitch
abstract: Eighteen musicians with absolute pitch (AP) confirmed by screening tests participated in tonal and verbal short-term-retention tasks. In the tonal task, subjects identified three successive pi-ano tones by their letter names. Recall of these note names after 18 sec of counting backwards was near perfect. Recall after an 18-sec delay filled with random piano tones was also near per-fect. In contrast, the same subjects demonstrated significant forgetting when required to retain letter trigrams while counting backwards for 18 sec. These results were essentially replicated in a second experiment using longer (27 sec) retention intervals, a more demanding verbal inter-ference task, and an active musical interference task (singing a descending scale). We interpret these results as indicating that retention of note names by possessors of AP is not limited to ver-bal encoding; rather, multiple codes (e.g., auditory, kinesthetic, and visual imagery) are proba-bly used.

title: Pre-attentive auditory processing of non-scale pitch in absolute pitch possessors
abstract: Absolute pitch (AP) refers to the ability to identify the pitch of sound without reference. To clarify the neurophysiological characteristics of AP, we compared mismatch negativity (MMN) elicited by scale and non-scale notes between AP possessors and non-AP individuals. Eight individuals who were able to identify pitch with perfect accuracy were defined as AP possessors. Eighteen participants who failed to achieve perfect accuracy were included in the non-AP group. We presented participants with two tone pairs, in a scale condition and a non-scale condition. The frequency ratios of the two pairs were the same. MMN over the frontal region in the non-scale condition was larger in the AP group than the non-AP group. In contrast, no such difference was observed between the two groups in the scale condition. The results suggest that pre-attentive processing of non-scale note sounds in the auditory cortex is a salient neurophysiological characteristic of AP.

title: Perceiving pitch absolutely: Comparing absolute and relative pitch possessors in a pitch memory task
abstract: BackgroundThe perceptual-cognitive mechanisms and neural correlates of Absolute Pitch (AP) are not fully understood. The aim of this fMRI study was to examine the neural network underlying AP using a pitch memory experiment and contrasting two groups of musicians with each other, those that have AP and those that do not.ResultsWe found a common activation pattern for both groups that included the superior temporal gyrus (STG) extending into the adjacent superior temporal sulcus (STS), the inferior parietal lobule (IPL) extending into the adjacent intraparietal sulcus (IPS), the posterior part of the inferior frontal gyrus (IFG), the pre-supplementary motor area (pre-SMA), and superior lateral cerebellar regions. Significant between-group differences were seen in the left STS during the early encoding phase of the pitch memory task (more activation in AP musicians) and in the right superior parietal lobule (SPL)/intraparietal sulcus (IPS) during the early perceptual phase (ITP 0–3) and later working memory/multimodal encoding phase of the pitch memory task (more activation in non-AP musicians). Non-significant between-group trends were seen in the posterior IFG (more in AP musicians) and the IPL (more anterior activations in the non-AP group and more posterior activations in the AP group).ConclusionSince the increased activation of the left STS in AP musicians was observed during the early perceptual encoding phase and since the STS has been shown to be involved in categorization tasks, its activation might suggest that AP musicians involve categorization regions in tonal tasks. The increased activation of the right SPL/IPS in non-AP musicians indicates either an increased use of regions that are part of a tonal working memory (WM) network, or the use of a multimodal encoding strategy such as the utilization of a visual-spatial mapping scheme (i.e., imagining notes on a staff or using a spatial coding for their relative pitch height) for pitch information.

title: The neural networks involved in pitch labeling of absolute pitch musicians
abstract: Investigating the neural substrates of auditory processing of absolute pitch musicians has relevance for understanding the capabilities of the human brain for plasticity. Electroencephalography was used to examine the N1 of auditory-evoked potentials from absolute pitch musicians, nonabsolute pitch musicians, and nonmusicians during tone labeling tasks with and without presentation of a reference tone. Source localization using low-resolution electromagnetic tomography revealed that when labeling tones without a reference, absolute pitch musicians generated greater activity than nonabsolute pitch musicians in the left and right hemispheres. This suggests that when required to label tones without an external reference, absolute pitch musicians have the ability to recruit a greater network than nonabsolute pitch musicians or nonmusicians.

title: Electrophysiological correlates of absolute pitch and relative pitch.
abstract: The temporal and spatial characteristics of the cortical processes responsible for absolute pitch (AP) and relative pitch (RP) were investigated by multi-channel event-related potentials (ERPs). Compared to listening, pitch-naming of tones in non-possessors of AP elicited three ERP components (P3b, parietal positive slow wave, frontal negative slow wave) over parietal and frontal scalp between 300 and 900 ms in latency, representing the cortical processes for RP. Possessors of AP elicited a unique left posterior-temporal negativity ('AP negativity') at 150 ms in both listening and pitch-naming conditions, representing the cortical processes for AP that were triggered by pitch input irrespective of the task the subjects were asked to perform. Congruency of auditory Stroop stimuli modulated the amplitudes of parietal positive slow wave (non-possessors of AP) and 'AP negativity' (possessors of AP), confirming that these components reflect the verbal labeling or pitch-to-pitch-name associative transformation that is central to pitch-naming. These results are consistent with the hypothesis that AP is subserved by neuronal processes in the left auditory association cortex that occur earlier and more automatically than the processes for RP, which involve broader areas of the cortex over longer periods of time.

title: Functional Anatomy of Musical Perception in Musicians
abstract: The present study used functional magnetic resonance to examine the cerebral activity pattern associated with musical perception in musicians and non-musicians. Musicians showed left dominant secondary auditory areas in the temporal cortex and the left posterior dorsolateral prefrontal cortex during a passive music listening task, whereas non-musicians demonstrated right dominant secondary auditory areas during the same task. A significant difference in the degree of activation between musicians and nonmusicians was noted in the bilateral planum temporale and the left posterior dorsolateral prefrontal cortex. The degree of activation of the left planum temporale correlated well with the age at which the person had begun musical training. Furthermore, the degree of activation in the left posterior dorsolateral prefrontal cortex and the left planum temporale correlated significantly with absolute pitch ability. The results indicated distinct neural activity in the auditory association areas and the prefrontal cortex of trained musicians. We suggest that such activity is associated with absolute pitch ability and the use-dependent functional reorganization produced by the early commencement of long-term training.

title: Musicians with absolute pitch show distinct neural activities in the auditory cortex.
abstract: Meg responses from musicians who had absolute pitch and from non-musicians were measured while they received different auditory stimuli. The parameters of single equivalent current dipoles (ECDs) were calculated for the N1m responses occurring in the auditory cortex. The location of the ECD for the noise burst was significantly posterior to the ECDs for the tones in the two hemispheres of the musicians, but not for those of the non-musicians. Further, in the left hemisphere the ECDs for the musicians were significantly posterior to those for the non-musicians. These results suggest distinct neural activities in the auditory cortex of musicians, which may be the result of cortical plasticity produced by training and/or an inherent cortical structural specificity.

title: Increased volume and function of right auditory cortex as a marker for absolute pitch.
abstract: Absolute pitch (AP) perception is the auditory ability to effortlessly recognize the pitch of any given tone without external reference. To study the neural substrates of this rare phenomenon, we developed a novel behavioral test, which excludes memory-based interval recognition and permits quantification of AP proficiency independently of relative pitch cues. AP- and non-AP-possessing musicians were studied with morphological and functional magnetic resonance imaging (fMRI) and magnetoencephalography. Gray matter volume of the right Heschl's gyrus (HG) was highly correlated with AP proficiency. Right-hemispheric auditory evoked fields were increased in the AP group. fMRI revealed an AP-dependent network of right planum temporale, secondary somatosensory, and premotor cortices, as well as left-hemispheric "Broca's" area. We propose the right HG as an anatomical marker of AP and suggest that a right-hemispheric network mediates AP "perception," whereas pitch "labeling" takes place in the left hemisphere.

title: Enhanced functional networks in absolute pitch
abstract: Functional networks in the human brain give rise to complex cognitive and perceptual abilities. While the decrease of functional connectivity is linked to neurological and psychiatric disorders, less is known about the consequences of increased functional connectivity. One population that has exceptionally enhanced perceptual abilities is people with absolute pitch (AP) - an ability to categorize tones into pitch classes without reference. AP has been linked to exceptional talent as well as to psychiatric and neurological conditions. Here we show that AP possessors have increased functional activation during music listening, as well as increased degrees, clustering, and local efficiency of functional correlations, with the difference being highest around the left superior temporal gyrus. Our results provide the first evidence that increased functional connectivity in a small-world brain network is related to exceptional perceptual abilities in a healthy population.

title: Enhanced Cortical Connectivity in Absolute Pitch Musicians: A Model for Local Hyperconnectivity
abstract: Connectivity in the human brain has received increased scientific interest in recent years. Although connection disorders can affect perception, production, learning, and memory, few studies have associated brain connectivity with graded variations in human behavior, especially among normal individuals. One group of normal individuals who possess unique characteristics in both behavior and brain structure is absolute pitch (AP) musicians, who can name the appropriate pitch class of any given tone without a reference. Using diffusion tensor imaging and tractography, we observed hyperconnectivity in bilateral superior temporal lobe structures linked to AP possession. Furthermore, volume of tracts connecting left superior temporal gyrus to left middle temporal gyrus predicted AP performance. These findings extend previous reports of exaggerated temporal lobe asymmetry, may explain the higher incidence of AP in special populations, and may provide a model for understanding the heightened connectivity that is thought to underlie savant skills and cases of exceptional creativity.

title: The Plasticity of the Superior Longitudinal Fasciculus as a Function of Musical Expertise: A Diffusion Tensor Imaging Study
abstract: Previous neuroimaging studies have demonstrated that musical expertise leads to functional alterations in language processing. We utilized diffusion tensor imaging (DTI) to investigate white matter plasticity in musicians with absolute pitch (AP), relative pitch and non-musicians. Using DTI, we analysed the fractional anisotropy (FA) of the superior longitudinal fasciculus (SLF), which is considered the most primary pathway for processing and production of speech and music. In association with different levels of musical expertise, we found that AP is characterized by a greater left than right asymmetry of FA in core fibres of the SLF. A voxel-based analysis revealed three clusters within the left hemisphere SLF that showed significant positive correlations with error rates only for AP-musicians in an AP-test, but not for musicians without AP. We therefore conclude that the SLF architecture in AP musicians is related to AP acuity. In order to reconcile our observations with general aspects of development of fibre bundles, we introduce the Pioneer Axon Thesis, a theoretical approach to formalize axonal arrangements of major white matter pathways.

title: Neuroanatomical correlates of musicianship as revealed by cortical thickness and voxel-based morphometry.
abstract: We used a multimethod approach to investigate the neuroanatomical correlates of musicianship and absolute pitch (AP). Cortical thickness measures, interregional correlations applied to these thicknesses, and voxel-based morphometry (VBM) were applied to the same magnetic resonance imaging data set of 71 musicians (27 with AP) and 64 nonmusicians. Cortical thickness was greater in musicians with peaks in superior temporal and dorsolateral frontal regions. Correlations between 2 seed points, centered on peaks of thickness difference within the right frontal cortex, and all other points across the cortex showed greater specificity of significant correlations among musicians, with fewer and more discrete areas correlating with the frontal seeds, including the superior temporal cortex. VBM of gray matter (GM)-classified voxels yielded a strongly right-lateralized focus of greater GM concentration in musicians centered on the posterolateral aspect of Heschl's gyrus. Together, these results are consistent with functional evidence emphasizing the importance of a frontotemporal network of areas heavily relied upon in the performance of musical tasks. Among musicians, contrasts of AP possessors and nonpossessors showed significantly thinner cortex among possessors in a number of areas, including the posterior dorsal frontal cortices that have been previously implicated in the performance of AP tasks.

title: The Neurocognitive Components of Pitch Processing: Insights from Absolute Pitch
abstract: The natural variability of pitch naming ability in the population (known as absolute pitch or AP) provides an ideal method for investigating individual differences in pitch processing and auditory knowledge formation and representation. We have demonstrated the involvement of different cognitive processes in AP ability that reflects varying skill expertise in the presence of similar early age of onset of music tuition. These processes were related to different regions of brain activity, including those involved in pitch working memory (right prefrontal cortex) and the long-term representation of pitch (superior temporal gyrus). They reflected expertise through the use of context dependent pitch cues and the level of automaticity of pitch naming. They impart functional significance to structural asymmetry differences in the planum temporale of musicians and establish a neurobiological basis for an AP template. More generally, they indicate variability of knowledge representation in the presence of environmental fostering of early cognitive development that translates to differences in cognitive ability.

title: Absolute Pitch and Planum Temporale
abstract: An increased leftward asymmetry of the planum temporale (PT) in absolute-pitch (AP) musicians has been previously reported, with speculation that early exposure to music influences the degree of PT asymmetry. To test this hypothesis and to determine whether a larger left PT or a smaller right PT actually accounts for the increased overall PT asymmetry in AP musicians, anatomical magnetic resonance images were taken from a right-handed group of 27 AP musicians, 27 nonmusicians, and 22 non-AP musicians. A significantly greater leftward PT asymmetry and a significantly smaller right absolute PT size for the AP musicians compared to the two control groups was found, while the left PT was only marginally larger in the AP group. The absolute size of the right PT and not the left PT was a better predictor of music group membership, possibly indicating "pruning" of the right PT rather than expansion of the left underlying the increased PT asymmetry in AP musicians. Although early exposure to music may be a prerequisite for acquiring AP, the increased PT asymmetry in AP musicians may be determined in utero, implicating possible genetic influences on PT asymmetry. This may explain why the increased PT asymmetry of AP musicians was not seen in the group of early beginning non-AP musicians.

title: In vivo evidence of structural brain asymmetry in musicians
abstract: Certain human talents, such as musical ability, have been associated with left-right differences in brain structure and function. In vivo magnetic resonance morphometry of the brain in musicians was used to measure the anatomical asymmetry of the planum temporale, a brain area containing auditory association cortex and previously shown to be a marker of structural and functional asymmetry. Musicians with perfect pitch revealed stronger leftward planum temporale asymmetry than nonmusicians or musicians without perfect pitch. The results indicate that outstanding musical ability is associated with increased leftward asymmetry of cortex subserving music-related functions.

title: The influence of music-elicited emotions and relative pitch on absolute pitch memory for familiar melodies
abstract: Levitin's findings that nonmusicians could produce from memory the absolute pitches of self-selected pop songs have been widely cited in the music psychology literature. These findings suggest that latent absolute pitch (AP) memory may be a more widespread trait within the population than traditional AP labelling ability. However, it has been left unclear what factors may facilitate absolute pitch retention for familiar pieces of music. The aim of the present paper was to investigate factors that may contribute to latent AP memory using Levitin's sung production paradigm for AP memory and comparing results to the outcomes of a pitch labelling task, a relative pitch memory test, measures of music-induced emotions, and various measures of participants' musical backgrounds. Our results suggest that relative pitch memory and the quality and degree of music-elicited emotions impact on latent AP memory.

title: Good Pitch Memory Is Widespread
abstract: Here we show that good pitch memory is widespread among adults with no musical training. We tested unselected college students on their memory for the pitch level of instrumental soundtracks from familiar television programs. Participants heard 5-s excerpts either at the original pitch level or shifted upward or downward by 1 or 2 semitones. They successfully identified the original pitch levels. Other participants who heard comparable excerpts from unfamiliar recordings could not do so. These findings reveal that ordinary listeners retain fine-grained information about pitch level over extended periods. Adults' reportedly poor memory for pitch is likely to be a by-product of their inability to name isolated pitches.

title: Dial A440 for absolute pitch: absolute pitch memory by non-absolute pitch possessors.
abstract: Listeners without absolute (or "perfect") pitch have difficulty identifying or producing isolated musical pitches from memory. Instead, they process the relative pattern of pitches, which remains invariant across pitch transposition. Musically untrained non-absolute pitch possessors demonstrated absolute pitch memory for the telephone dial tone, a stimulus that is always heard at the same absolute frequency. Listeners accurately classified pitch-shifted versions of the dial tone as "normal," "higher than normal" or "lower than normal." However, the role of relative pitch processing was also evident, in that listeners' pitch judgments were also sensitive to the frequency range of stimuli.

title: Absolute Pitch May Not Be So Absolute
abstract: Most people cannot name the musical note that corresponds to a particular pitch without being provided a reference note, but those people with absolute pitch (AP) can do this accurately. Early experience during a developmental period is often thought to convey identity and stability of the note categories in people with AP, but the plasticity of these categories has not been investigated. Here we provide the first evidence that the note categories of adults with AP can change with listening experience. Participants with AP showed shifts in perception in direct accord with prior exposure to music detuned by a fraction of a semitone. This suggests that the apparent stability of AP categories is conferred not by early experience but rather by the cultural norms adopted for tuning music.

title: Pitch and Plasticity: Insights from the Pitch Matching of Chords by Musicians with Absolute and Relative Pitch
abstract: Absolute pitch (AP) is a form of sound recognition in which musical note names are associated with discrete musical pitch categories. The accuracy of pitch matching by non-AP musicians for chords has recently been shown to depend on stimulus familiarity, pointing to a role of spectral recognition mechanisms in the early stages of pitch processing. Here we show that pitch matching accuracy by AP musicians was also dependent on their familiarity with the chord stimulus. This suggests that the pitch matching abilities of both AP and non-AP musicians for concurrently presented pitches are dependent on initial recognition of the chord. The dual mechanism model of pitch perception previously proposed by the authors suggests that spectral processing associated with sound recognition primes waveform processing to extract stimulus periodicity and refine pitch perception. The findings presented in this paper are consistent with the dual mechanism model of pitch, and in the case of AP musicians, the formation of nominal pitch categories based on both spectral and periodicity information.

title: An Empirical Reevaluation of Absolute Pitch: Behavioral and Electrophysiological Measurements
abstract: Here, we reevaluated the “two-component” model of absolute pitch (AP) by combining behavioral and electrophysiological measurements. This specific model postulates that AP is driven by a perceptual encoding ability (i.e., pitch memory) plus an associative memory component (i.e., pitch labeling). To test these predictions, during EEG measurements AP and non-AP (NAP) musicians were passively exposed to piano tones (first component of the model) and additionally instructed to judge whether combinations of tones and labels were conceptually associated or not (second component of the model). Auditory-evoked N1/P2 potentials did not reveal differences between the two groups, thus indicating that AP is not necessarily driven by a differential pitch encoding ability at the processing level of the auditory cortex. Otherwise, AP musicians performed the conceptual association task with an order of magnitude better accuracy and shorter RTs than NAP musicians did, this result clearly pointing to distinctive conceptual associations in AP possessors. Most notably, this behavioral superiority was reflected by an increased N400 effect and accompanied by a subsequent late positive component, the latter not being distinguishable in NAP musicians.

title: Functional anatomy of musical processing in listeners with absolute pitch and relative pitch.
abstract: We used both structural and functional brain imaging techniques to investigate the neural basis of absolute pitch (AP), a specialized skill present in some musicians. By using positron emission tomography, we measured cerebral blood flow during the presentation of musical tones to AP possessors and to control musicians without AP. Listening to musical tones resulted in similar patterns of increased cerebral blood flow in auditory cortical areas in both groups, as expected. The AP group also demonstrated activation of the left posterior dorsolateral frontal cortex, an area thought to be related to learning conditional associations. However, a similar pattern of left dorsolateral frontal activity was also observed in non-AP subjects when they made relative pitch judgments of intervals, such as minor or major. Conversely, activity within the right inferior frontal cortex was observed in control but not in AP subjects during the interval-judgment task, suggesting that AP possessors need not access working memory mechanisms in this task. MRI measures of cortical volume indicated a larger left planum temporale in the AP group, which correlated with performance on an pitch-naming task. Our findings suggest that AP may not be associated with a unique pattern of cerebral activity but rather may depend on the recruitment of a specialized network involved in the retrieval and manipulation of verbal-tonal associations.

title: Neural processing of musical timbre by musicians, nonmusicians, and musicians possessing absolute pitch.
abstract: Cognitive event-related potentials (ERPs) were measured during a timbre discrimination task from three subject groups varying in musical experience. The P3 component of the ERP was recorded from musicians with absolute pitch, musicians without absolute pitch, and nonmusicians during a task comprising timbres of varying difficulty. The three-timbre series, all of which consisted of the same pitch, were (1) string instruments in the same family (cello and viola), (2) flutes made of different materials (silver and wood), and (3) instruments of slightly different size (B-flat versus F tubas). The amplitude and latency of the P3 component varied systematically as a function of musical experience and type of timbre discrimination. The difficult timbre task resulted in mean P3 amplitudes which were larger for musicians relative to nonmusicians, however P3 amplitudes were similar for the two additional timbre series. The mean P3 latencies for musicians were shorter when compared to nonmusicians across all three series. In comparison, the AP subjects displayed the shortest mean P3 latencies, but had smaller P3 amplitudes relative to both musicians and nonmusicians. The implications of these findings suggest that perceptual tasks involving one of the fundamental building blocks of music, namely timbre, does elicit differential brain activity from memory or information processing systems from subjects with varying degrees of musical training.

title: People with Absolute Pitch Process Tones Without Producing a P300
abstract: The P300 is a positive-going component of the event-related potential. In subjects with absolute, or "perfect," pitch, the P300 elicited by the less frequent of two auditory probes is small or absent. In these subjects, visual probes elicit a normal P300. These results support the view of P300 as a manifestation of the updating of working memory.

title: Dissociation of human mid-dorsolateral from posterior dorsolateral frontal cortex in memory processing.
abstract: Work with non-human primates had previously demonstrated that the mid-dorsolateral frontal cortex, which comprises cytoarchitectonic areas 46 and 9, plays a critical role in the performance of non-spatial self-ordered working memory tasks, whereas the immediately adjacent posterior dorsolateral frontal cortex (area 8) is critical for the learning and performance of visual conditional associative tasks. The present study used positron emission tomography with magnetic resonance imaging to demonstrate the existence, within the human brain, of these two functionally distinct subdivisions of the lateral frontal cortex. These findings provide direct evidence that, just as the monkey brain, the human lateral frontal cortex is functionally heterogeneous and that comparable anatomical areas underlie similar functions in the two species.

title: Nonspatial conditional learning impaired in patients with unilateral frontal but not unilateral temporal lobe excisions
abstract: The present study examined the effect of unilateral frontal- or temporal-lobe excisions on the acquisition of a conditional task requiring that the subjects respond to each one of six different coloured stimuli by selecting, from a set of six abstract designs, the correct design for each stimulus. Patients with excisions from the left or right frontal cortex were impaired in learning this task, whereas patients with left or right temporal-lobe excisions, with or without radical involvement of the hippocampal region, were not impaired. These findings demonstrate that the major role played by the frontal cortex in the acquisition of conditional responses is a general one and not restricted to situations involving different movements.

title: Conditional Associative Memory for Musical Stimuli in Nonmusicians: Implications for Absolute Pitch
abstract: A previous positron emission tomography (PET) study of musicians with and without absolute pitch put forth the hypothesis that the posterior dorsolateral prefrontal cortex is involved in the conditional associative aspect of the identification of a pitch. In the work presented here, we tested this hypothesis by training eight nonmusicians to associate each of four different complex musical sounds (triad chords) with an arbitrary number in a task designed to have limited analogy to absolute-pitch identification. Each subject under-went a functional magnetic resonance imaging scanning procedure both before and after training. Active condition (identification of chords)- control condition (amplitude-matched noise bursts) comparisons for the pretraining scan showed no significant activation maxima. The same comparison for the posttraining scan revealed significant peaks of activation in posterior dorsolateral prefrontal, ventrolateral prefrontal, and parietal areas. A conjunction analysis was performed to show that the posterior dorsolateral prefrontal activity in this study is similar to that observed in the aforementioned PET study. We conclude that the posterior dorsolateral prefrontal cortex is selectively involved in the conditional association aspect of our task, as it is in the attribution of a verbal label to a note by absolute-pitch musicians.

title: Effects of Musical Training and Absolute Pitch on the Neural Processing of Melodic Intervals: A P3 Event-Related Potential Study
abstract: During perceptual tasks involving the discrimination of musical intervals, event-related potentials, specifically the P3, were measured for three subject groups: musicians without absolute pitch, musicians with absolute pitch, and nonmusicians. The two interval-discrimination tasks were a simple two-note contour task and a difficult interval-size discrimination task. Clear effects on the neural waveforms were found for both training and the presence of the absolute pitch ability. In general, training increases the amplitude and shortens the latency of the P3, while the absolute pitch ability reduces the amplitude and shortens the latency, or eliminates the P3 altogether. The absolute pitch effect may be due to the use of a long-term memory strategy involved in the correct performance of the discrimination task rather than performing the task by updating working memory each time a target occurs. Finally, these data are contrasted with those from studies involving sine tones and timbrediscrimination tasks.

title: Effects of musical training and absolute pitch ability on event-related activity in response to sine tones.
abstract: The neural correlates of music perception have received relatively little scientific attention. The neural activity of listeners without musical training (N = 11), highly trained musicians (N = 14), and musicians possessing "absolute pitch" (AP) ability (N = 10) have been measured. Major differences were observed in the P3, an endogenous event-related potential (ERP), which is thought to be a neurophysiological manifestation of working memory processing. The P3 was elicited using the classical "oddball" paradigm with a sine-tone series. Subjects' musical backgrounds were evaluated with a survey questionnaire. AP ability was verified with an objective pitch identification test. The P3 amplitude, latency and wave shape were evaluated along with each subjects' performance score and musical background. The AP subjects showed a significantly smaller P3 amplitude than either the musicians or nonmusicians, which were nearly identical. The P3 latency was shortest for the AP subjects, and was longer for the nonmusicians. Performance scores were uniformly high in all three groups. It is concluded that AP subjects do indeed exhibit P3 ERPs, albeit with smaller amplitudes and shorter latencies. The differences in neural activity between the musicians and AP subjects were not due to musical training, as the AP subjects had similar musical backgrounds to the musician group. It is also concluded that persons with the AP ability may have superior auditory sensitivity at cortical levels and/or use unique neuropsychological strategies when processing tones.

title: Thirty years and counting: finding meaning in the N400 component of the event-related brain potential (ERP).
abstract: We review the discovery, characterization, and evolving use of the N400, an event-related brain potential response linked to meaning processing. We describe the elicitation of N400s by an impressive range of stimulus types--including written, spoken, and signed words or pseudowords; drawings, photos, and videos of faces, objects, and actions; sounds; and mathematical symbols--and outline the sensitivity of N400 amplitude (as its latency is remarkably constant) to linguistic and nonlinguistic manipulations. We emphasize the effectiveness of the N400 as a dependent variable for examining almost every aspect of language processing and highlight its expanding use to probe semantic memory and to determine how the neurocognitive system dynamically and flexibly uses bottom-up and top-down information to make sense of the world. We conclude with different theories of the N400's functional significance and offer an N400-inspired reconceptualization of how meaning processing might unfold.

title: Event‐related potential (ERP) studies of memory encoding and retrieval: A selective review
abstract: As event‐related brain potential (ERP) researchers have increased the number of recording sites, they have gained further insights into the electrical activity in the neural networks underlying explicit memory. A review of the results of such ERP mapping studies suggests that there is good correspondence between ERP results and those from brain imaging studies that map hemodynamic changes. This concordance is important because the combination of the high temporal resolution of ERPs with the high spatial resolution of hemodynamic imaging methods will provide a greatly increased understanding of the spatio‐temporal dynamics of the brain networks that encode and retrieve explicit memories.  2000.

title: Absolute Pitch and Event-Related Brain Potentials
abstract: An event-related brain potential (ERP) component called mismatch negativity (MMN) is elicited by physically deviant auditory stimuli presented among repetitive, "standard," stimuli. MMN reflects a mismatch process between sensory input from the deviant stimulus and a shortduration neuronal representation developed by the standard stimulus. The MMN amplitude is known to correlate with pitch-discrimination performance. The purpose of the present study was to investigate whether the MMN is different in absolute pitch (AP) possessors and nonpossessors. ERPs were recorded from AP and non-AP groups, which were matched with regard to musical training. It was found that deviant stimuli differing from standard tones by a quartertone or a semitone elicited an MMN irrespective of whether the stimulus was located on (white key/black key) or off the Western musical scale. These results were obtained with both sinusoidal and piano tones. The MMN was larger and earlier when the stimuli were piano tones than when they were sinusoidal tones and when the standard-deviant difference amounted to a semitone rather than a quartertone. However, differences between the groups were not found in auditory information processing reflected by the MMN component of the ERP. In the light of the earlier MMN results showing a close correlation between the MMN and pitch- discrimination accuracy, it might be concluded that pitch discrimination and identification are based on different brain mechanisms. In addition, the differences in the MMN amplitude and latency between sinusoidal and piano tones might be interpreted as suggesting that sensory memory traces, as reflected by the MMN, are capable of storing information of very complex sound structures also.

title: Language outside the focus of attention: The mismatch negativity as a tool for studying higher cognitive processes
abstract: Which aspects of language and cognitive processing take place irrespective of whether subjects focus their attention on incoming stimuli and are, in this sense, automatic? The Mismatch Negativity (MMN), a neurophysiological brain response recorded in the EEG and MEG, is elicited by attended and unattended stimuli alike. Recent studies investigating the cognitive processes underlying spoken language processing found that even under attentional withdrawal, MMN size and topography reflect the activation of memory traces for language elements in the human brain. Familiar sounds of one's native language elicit a larger MMN than unfamiliar sounds, and at the level of meaningful language units, words elicit a larger MMN than meaningless pseudowords. This suggests that the MMN reflects the activation of memory networks for language sounds and spoken words. Unattended word stimuli elicit an activation sequence starting in superior-temporal cortex and rapidly progressing to left-inferior-frontal lobe. The spatio-temporal patterns of cortical activation depend on lexical and semantic properties of word stems and affixes, thus indicating that the MMN can give clues about lexico-semantic information processing stored in long term memory. At the syntactic level, MMN size was found to reflect whether a word string conforms to abstract grammatical rules. This growing body of results suggests that lexical, semantic and syntactic information can be processed by the central nervous system outside the focus of attention in a largely automatic manner. Analysis of spatio-temporal patterns of generator activations underlying the MMN to speech may be an important tool for investigating the brain dynamics of spoken language processing and the activated distributed cortical circuits acting at long-term memory traces.

title: Mismatch negativity (MMN): perspectives for application.
abstract: This article discusses the reasons of the wide applicability of the mismatch negativity (MMN) generated by the brain's automatic response to change in auditory stimulation. Essential here is that the MMN (and its magnetic equivalent MMNm) currently provides the only objective measure of the central auditory function. The MMN can be measured in the absence of attention and without any task requirements, which makes it particularly suitable for testing different clinical populations and infants.

title: Early selective-attention effect on evoked potential reinterpreted.
abstract: In a dichotic listening situation stimuli were presented one at a time and at random to either ear of the subject at constant inter-stimulus intervals of 800 msec. The subject's task was to detect and count occasional slightly different stimuli in one ear. In Experiment 1, these ‘signal’ stimuli were slightly louder, and in Experiment 2 they had a slightly higher pitch, than the much more frequent, ‘standard’, stimuli. In both experiments signals occured randomly at either ear. Separate evoked potentials from three different locations were recorded for each of the four kinds of stimuli (attended signals, unattended signals, attended standards, unattended standards). Contrary to Hillyard et al. (1973), no early (N 1 component) evoked-potential enhancement was observed to stimuli to the attended ear as compared with those to the unattended ear, but there was a later negative shift superimposed on potentials elicited by the former stimuli. This negative shift was considered identical to the N 1 enhancement of Hillyard and his colleagues which in the present study was forced, by the longer inter-stimulus interval used, to demonstrate temporal dissociation with the N 1 component. The ‘Hillyard effect’ was, consequently, explained as being caused by a superimposition of a CNV kind of negative shift on the evoked potential to the attended stimuli rather than by a growth of the ‘real’ N 1 component of the evoked potential.

title: The mismatch negativity: A review of underlying mechanisms
abstract: The mismatch negativity (MMN) is a brain response to violations of a rule, established by a sequence of sensory stimuli (typically in the auditory domain) [Näätänen R. Attention and brain function. Hillsdale, NJ: Lawrence Erlbaum; 1992]. The MMN reflects the brain’s ability to perform automatic comparisons between consecutive stimuli and provides an electrophysiological index of sensory learning and perceptual accuracy. Although the MMN has been studied extensively, the neurophysiological mechanisms underlying the MMN are not well understood. Several hypotheses have been put forward to explain the generation of the MMN; amongst these accounts, the “adaptation hypothesis” and the “model adjustment hypothesis” have received the most attention. This paper presents a review of studies that focus on neuronal mechanisms underlying the MMN generation, discusses the two major explanatory hypotheses, and proposes predictive coding as a general framework that attempts to unify both.

title: Mismatch Negativity: Different Water in the Same River
abstract: The mismatch negativity (MMN) is a frontal negative deflection in the human event-related potential that typically occurs when a repeating auditory stimulus changes in some manner. The MMN can be elicited by many kinds of stimulus change, varying from simple changes in a single stimulus feature to abstract changes in the relationship between stimuli. The main intracerebral sources for the MMN are located in the auditory cortices of the temporal lobe. Since it occurs whether or not stimuli are being attended, the MMN represents an automatic cerebral process for detecting change. The MMN is clinically helpful in terms of demonstrating disordered sensory processing or disordered memory in groups of patients. Improvements in the techniques for measuring the MMN and in the paradigms for eliciting it will be needed before the MMN can become clinically useful as an objective measurement of such disorders in individual patients.

title: The mismatch negativity in cognitive and clinical neuroscience: Theoretical and methodological considerations
abstract: Mismatch negativity (MMN) component of the event-related brain potentials has become popular in cognitive and clinical brain research during the recent years. It is an early response to a violation of an auditory rule such as an infrequent change in the physical feature of a repetitive sound. There is a lot of evidence on the association of the MMN parameters and behavioral discrimination ability, although this relationship is not always straight-forward. Since the MMN reflects sound discrimination accuracy, it can be used for probing how well different groups of individuals perceive sound differences, and how training or remediation affects this ability. In the present review, we first introduce some of the essential MMN findings in probing sound discrimination, memory, and their deficits. Thereafter, issues which need to be taken into account in MMN investigations as well as new improved recording paradigms are discussed.

title: Involuntary Attention and Distractibility as Evaluated with Event-Related Brain Potentials
abstract: This article reviews recent event-related brain potential (ERP) studies of involuntary attention and distractibility in response to novelty and change in the acoustic environment. These studies show that the mismatch negativity, N1 and P3a ERP components elicited by deviant or novel sounds in an unattended sequence of repetitive stimuli index different processes along the course to involuntary attention switch to distracting stimuli. These studies used new auditory-auditory and auditory-visual distraction paradigms, which enable one to assess objectively abnormal distractibility in several clinical patient groups, such as those suffering from closed-head injuries or chronic alcoholism.

title: Updating P300: An integrative theory of P3a and P3b
abstract: The empirical and theoretical development of the P300 event-related brain potential (ERP) is reviewed by considering factors that contribute to its amplitude, latency, and general characteristics. The neuropsychological origins of the P3a and P3b subcomponents are detailed, and how target/standard discrimination difficulty modulates scalp topography is discussed. The neural loci of P3a and P3b generation are outlined, and a cognitive model is proffered: P3a originates from stimulus-driven frontal attention mechanisms during task processing, whereas P3b originates from temporal-parietal activity associated with attention and appears related to subsequent memory processing. Neurotransmitter actions associating P3a to frontal/dopaminergic and P3b to parietal/norepinephrine pathways are highlighted. Neuroinhibition is suggested as an overarching theoretical mechanism for P300, which is elicited when stimulus detection engages memory operations.

title: Decision-related cortical potentials during an auditory signal detection task with cued observation intervals.
abstract: Cortical-evoked potentials were recorded from human subjects performing an auditory detection task with confidence rating responses. Unlike earlier studies that used similar procedures, the observation interval during which the auditory signal could occur was clearly marked by a visual cue light. By precisely defining the observation interval and, hence, syncrhonizing all perceptual decisions to the evoked potential averaging epoch, it was possible to demonstrate that high-confidence false alarms for accompanied by late-positive P3 components equivalent to those for equally confident hits. Moreover the hit and false alarm evoked potentials were found to covary similarily with variations in confidence rating and to have similar amplitude distributions over the scalp. In a second experiment wherein the signal intensity was increased to make signal presence and signal absence clearly discriminable and the a priori probability of signal presentation was varied from .5 to .9, it was demonstrated that correct rejections can be associated with a P3 component larger than that for hits. Thus it was possible to show, within the signal detection paradigm, how the two major factors of decision confidence and expectancy are reflected in the P3 component of the cortical-evoked potential.

title: P3a and P3b from typical auditory and visual stimuli
abstract: Target/standard discrimination difficulty was manipulated systematically to assess how this variable affects target and nontarget P300 scalp distributions for both auditory and visual stimuli.



A 3-stimulus paradigm (target, standard, nontarget) was employed in which subjects (n = 16) responded only to an infrequently occurring target stimulus. The perceptual discrimination difficulty between the target and more frequently occurring standard stimuli was varied as Easy or Difficult in different conditions, while holding the nontarget stimulus properties constant.



When target/standard discrimination was Easy, P300 amplitude was larger for the target than the nontarget across all electrode sites, and both demonstrated parietal maximums. In contrast, when target/standard discrimination was Difficult, target amplitude (P3b) was larger parietally and occurred later than nontarget components, whereas nontarget amplitude (P3a) was larger and earlier than the target P300 over the frontal electrode sites. Similar outcomes across task conditions were obtained for both auditory and visual stimuli.



The findings suggest that target/standard discrimination difficulty, rather than stimulus novelty, determines P3a generation for both auditory and visual stimulus modalities.

title: The novelty P3: an event-related brain potential (ERP) sign of the brain's evaluation of novelty
abstract: A review of the literature that examines event-related brain potentials (ERPs) and novelty processing reveals that the orienting response engendered by deviant or unexpected events consists of a characteristic ERP pattern, comprised sequentially of the mismatch negativity (MMN) and the novelty P3 or P3a. A wide variety of evidence suggests that the MMN reflects the detection of deviant events, whereas the P3a is associated more with the evaluation of those events for subsequent behavioral action. On the scalp, the novelty P3a is comprised of at least two aspects, one frontal the other posterior, each with different cognitive (and presumably neurologic) correlates. Intracranial ERP investigations and studies of patients with localized brain lesions (and, to some extent, fMRI data) converge with the scalp-recorded data in suggesting a widespread neural network, the different aspects of which respond differentially to stimulus and task characteristics.

title: Decreased response to novel stimuli after prefrontal lesions in man.
abstract: Experiments were conducted to study the contribution of prefrontal cortex to the generation and modulation of two varieties of P300 activity. Control subjects generated typical parietal maximal P300 responses to detected target stimuli. Unexpected, novel auditory stimuli presented to controls generated an earlier latency, fronto-centrally distributed P300 response. A similar earlier latency, fronto-central P300 is generated to unexpected, novel visual stimuli. The occurrence of this phenomenon in both the auditory and visual modalities suggests that it may reflect neural activity of a common CNS system involved in the orienting response. Subjects with unilateral prefrontal damage generated P300 complexes to target stimuli that did not differ from the control responses. Prefrontal damage, however, resulted in a specific defect in the P300 response to the unexpected novel stimulus. Prefrontal patients showed neither N200 enhancement nor the fronto-central P300 response to the novel stimulus that was found in control subjects. These findings indicate that prefrontal regions are critical for the organism's response to unexpected novel stimuli. Abnormalities in prefrontal control of sensory-limbic integration may be a critical element in the decreased P300 to novel stimuli found in these unilateral prefrontal lesioned patients. It is suggested that major features of the human frontal lobe syndrome may be explained by a physiological inability to control attention and orientation systems after prefrontal damage.

title: Role of human prefrontal cortex in attention control.
abstract: Without a functioning dorsolateral prefrontal cortex, humans are stimulus bound and have little confidence in their ability to interact with the environment. Deficits in inhibitory control of external and internal processes coupled with impaired temporal coding of stimuli and detection capacity for novel events leave the patient functioning in a noisy internal environment without critical spatiotemporal cues. Some of these proposals are similar to those of Nauta (104). Based on connectivity of the prefrontal cortex, Nauta suggested that this region was ideally suited to generate and evaluate internal models of action. It is proposed that, in addition to this generation function, the prefrontal cortex is crucial for detecting changes in the external environment and for discriminating internally and externally derived models of the world. This chapter has described a cascade of deficits that result from damage to the dorsolateral prefrontal cortex. Awareness of the sensory world, and of the apparent stream of internal and external events, is impaired by deficits in novelty detection. Changes in the world, internal or external, may not be noticed in a noisy internal milieu. These deficits contribute to impaired reality monitoring and to a subsequent lack of confidence in behavior. An inability to bridge temporal gaps and temporally sequence internal events, together with deficits in inhibitory control systems, contribute to an impairment in the ability to generate coherent representations of alternate or counterfactual realities.

title: Contributions of temporal-parietal junction to the human auditory P3
abstract: The P3 component of the event-related potential (ERP) is generated in humans and other mammalian species when attention is drawn to infrequent stimuli. We assessed the role of subregions of human posterior association cortex in auditory P3 generation in groups of patients with focal cortical lesions. Auditory P3s were recorded to target (P3b) and unexpected novel stimuli (P3a) in monaural and dichotic signal detection experiments. Two groups of patients were studied with lesions of: (1) temporal-parietal junction including posterior superior temporal plane and adjacent caudal inferior parietal cortex; and (2) the lateral parietal lobe including the rostral inferior parietal lobe and portions of superior parietal lobe. Extensive lateral parietal cortex lesions had no effect on the P3. In contrast, discrete unilateral lesions centered in the posterior superior temporal plane eliminated both the auditory P3b and P3a at electrodes over the posterior scalp. The results indicate that auditory association cortex in the human temporal-parietal junction is critical for auditory P3 generation.

title: Distraction of task-relevant information processing by irrelevant changes in auditory, visual, and bimodal stimulus features: a behavioral and event-related potential study.
abstract: Distractibility with auditory, visual, and bimodal stimulus changes was investigated using an audio-visual distraction paradigm. Participants were asked to discriminate between equiprobable short and long audio-visual stimuli. Infrequently, the auditory, the visual, or both parts of the stimuli changed. These rare deviations (deviants) were irrelevant for the actual task. The influence of the three types of deviant stimuli on the processing of task-relevant information was assessed with behavioral and event-related potential (ERP) measures assuming that bimodal deviants would lead to an increase in distraction. Behavioral and ERP results did not support this assumption, as reaction time (RT) prolongation and components amplitudes did not differ significantly for auditory and bimodal deviants. It is suggested that a maximal threshold of distraction accounts for these results. In addition, the processing of bimodal deviations was assessed. Audio-visual interactions were found following modality-specific deviance detection suggesting that integration only occurs with involuntary attention switching to task-irrelevant changes.

title: Increased cortical surface area of the left planum temporale in musicians facilitates the categorization of phonetic and temporal speech sounds
abstract: We measured musicians and non-musicians by using structural magnetic resonance imaging to investigate relationships between cortical features of the left planum temporale (PT) and the categorization of consonant-vowel (CV) syllables and their reduced-spectrum analogues. The present work is based on previous functional studies consistently showing that the left PT is particularly responsive to transient acoustic features in CV syllables and their reduced-spectrum analogues, and on striking evidence pointing to structural alterations of the left PT as a function of musicianship. By combining these two observations, we hypothesized to find that differences in cortical surface area (SA) and cortical thickness (CT) of the left PT in musicians may facilitate the categorization of fast-changing phonetic cues. Behavioural results indicated that musicians and non-musicians achieved a comparable performance in the categorization of CV syllables, whereas the musicians performed significantly better than the controls in the more demanding reduced-spectrum condition. This better behavioural performance corresponds to an increased cortical SA of the left PT in musicians compared to non-musicians. No differences in CT of the left PT were found between groups. In line with our predictions, we revealed a positive correlation between cortical SA of the left PT in musicians and the behavioural performance during the acoustically more demanding reduced-spectrum condition. Hence, we provide first evidence for a relationship between musical expertise, cortical SA of the left PT, and the processing of fast-changing phonetic cues.

title: Neurofunctional and behavioral correlates of phonetic and temporal categorization in musically trained and untrained subjects.
abstract: The perception of rapidly changing verbal and nonverbal auditory patterns is a fundamental prerequisite for speech and music processing. Previously, the left planum temporale (PT) has been consistently shown to support the discrimination of fast changing verbal and nonverbal sounds. Furthermore, it has been repeatedly shown that the functional and structural architecture of this supratemporal brain region differs as a function of musical training. In the present study, we used the functional magnetic resonance imaging technique, in a sample of professional musicians and nonmusicians, in order to examine the functional contribution of the left PT to the categorization of consonant-vowel syllables and their reduced-spectrum analogues. In line with our hypothesis, the musicians showed enhanced brain responses in the left PT and superior discrimination abilities in the reduced-spectrum condition. Moreover, we found a positive correlation between the responsiveness of the left PT and the performance in the reduced-spectrum condition across all subjects irrespective of musical expertise. These results have implications for our understanding of musical expertise in relation to segmental speech processing.

title: Multiple choice vocabulary test MWT as a valid and short test to estimate premorbid intelligence
abstract: The discrepancy between current and premorbid ability is a relevant indicator of acquired mental impairment, which itself is closely related to general cerebral dysfunction. The use of tests sensitive to cerebral dysfunction, raises relatively few problems compared with tests being resistent that are used to estimate premorbid mental ability. For premorbid ability, verbal tests assessing knowledge, especially vocabulary, have been shown to be valid. A test, possibly more insensitive to brain dysfunction than the ones usually administered, is the multiple choice vocabulary test (MWT = Mehrfachwahl‐Wortschatz‐Test). At present only German versions are available. They are presented in some detail because of their advantages. Construction of the MWT is simple, and it can be easily administered in about five minutes. The results correlate fairly well with global IQ in healthy adults (median of r = 0.72 in 22 samples) and are more insensitive to current disturbances than such tests as the WAIS vocabulary test. The limitations of premorbid tests with respect to diagnostic validity are discussed. It is concluded, that studies which do not control premorbid intelligence have to be considered as a “malpractice” and should not be accepted by scientists.

title: Simultaneously active pre-attentive representations of local and global rules for sound sequences in the human brain.
abstract: Regular sequences of sounds (i.e., non-random) can usually be described by several, equally valid rules. Rules allowing extrapolation from one sound to the next are termed local rules, those that define relations between temporally non-adjacent sounds are termed global rules. The aim of the present study was to determine whether both local and global rules can be simultaneously extracted from a sound sequence even when attention is directed away from the auditory stimuli. The pre-attentive representation of a sequence of two alternating tones (differing only in frequency) was investigated using the mismatch negativity (MMN) auditory event-related potential. Both local- and global-rule violations of tone alternation elicited the MMN component while subjects ignored the auditory stimuli. This finding suggests that (a) pre-attentive auditory processes can extract both local and global rules from sound sequences, and (b) that several regularity representations of a sound sequence are simultaneously maintained during the pre-attentive phase of auditory stimulus processing.

title: The concept of auditory stimulus representation in cognitive neuroscience.
abstract: The sequence of neurophysiological processes elicited in the auditory system by a sound is analyzed in search of the stage at which the processes carrying sensory information cross the borderline beyond which they directly underlie sound perception. Neurophysiological data suggest that this transition occurs when the sensory input is mapped onto the physiological basis of sensory memory in the auditory cortex. At this point, the sensory information carried by the stimulus-elicited process corresponds, for the first time, to that contained by the actual sound percept. Before this stage, the sensory stimulus code is fragmentary, lacks the time dimension, cannot enter conscious perception, and is not accessible to top-down processes (voluntary mental operations). On these grounds, 2 distinct stages of auditory sensory processing, prerepresentational and representational, can be distinguished.

title: Removing electroencephalographic artifacts by blind source separation.
abstract: Eye movements, eye blinks, cardiac signals, muscle noise, and line noise present serious problems for electroencephalographic (EEG) interpretation and analysis when rejecting contaminated EEG segments results in an unacceptable data loss. Many methods have been proposed to remove artifacts from EEG recordings, especially those arising from eye movements and blinks. Often regression in the time or frequency domain is performed on parallel EEG and electrooculographic (EOG) recordings to derive parameters characterizing the appearance and spread of EOG artifacts in the EEG channels. Because EEG and ocular activity mix bidirectionally, regressing out eye artifacts inevitably involves subtracting relevant EEG signals from each record as well. Regression methods become even more problematic when a good regressing channel is not available for each artifact source, as in the case of muscle artifacts. Use of principal component analysis (PCA) has been proposed to remove eye artifacts from multichannel EEG. However, PCA cannot completely separate eye artifacts from brain signals, especially when they have comparable amplitudes. Here, we propose a new and generally applicable method for removing a wide variety of artifacts from EEG records based on blind source separation by independent component analysis (ICA). Our results on EEG data collected from normal and autistic subjects show that ICA can effectively detect, separate, and remove contamination from a wide variety of artifactual sources in EEG records with results comparing favorably with those obtained using regression and PCA methods. ICA can also be used to analyze blink-related brain activity.

title: Asymmetry of evoked potential latency to speech sounds predicts the ear advantage in dichotic listening.
abstract: The functional organization of the human auditory cortex is still not well understood with respect to speech perception and language lateralization. Especially, there is comparatively little data available in the brain imaging literature focusing on the timing of phonetic processing. We recorded auditory-evoked potentials (AEP) from 27 scalp and additional EOG channels in 12 healthy volunteers performing a free report dichotic listening task with simple speech sounds (CV syllables: [ba], [da], [ga], [pa], [ta], [ka]). ERP analysis employed independent components analysis (ICA) wavelet denoising for artifact reduction and improvement of the SNR. The main finding was a 15-ms shorter average latency of the N1-AEP recorded from the scalp approximately overlying the left supratemporal cortical plane compared to the N1-AEP over the homologous right side. Corresponding N1 amplitudes did not differ between these sites. The individual AEP latency differences significantly correlated with the ear advantage as an index of speech/language lateralization. The behaviorally relevant difference in N1 latency between the hemispheres indicates that an important key to understanding speech perception is to consider the functional implications of neuronal event timing.

title: The mismatch negativity (MMN) in basic research of central auditory processing: A review
abstract: In the present article, the basic research using the mismatch negativity (MMN) and analogous results obtained by using the magnetoencephalography (MEG) and other brain-imaging technologies is reviewed. This response is elicited by any discriminable change in auditory stimulation but recent studies extended the notion of the MMN even to higher-order cognitive processes such as those involving grammar and semantic meaning. Moreover, MMN data also show the presence of automatic intelligent processes such as stimulus anticipation at the level of auditory cortex. In addition, the MMN enables one to establish the brain processes underlying the initiation of attention switch to, conscious perception of, sound change in an unattended stimulus stream.

title: People with absolute pitch process tones with producing P300
abstract: We recorded a P300 component of event-related potentials associated with auditory oddball tasks in nine absolute pitch (AP) possessors and seven non-AP possessors. The previous studies demonstrated that AP possessors did not appear to employ working memory during auditory oddball tasks because they have a fixed tonal template in their memories. However, the present findings showed that the AP possessors exhibited similar P300 as the non-AP possessors and did update the tonal context in the auditory oddball tasks. This result suggests that the AP possessors do not always refer to the fixed tonal template in their memories when executing the oddball tasks and they employ working memory properly according to the difficulty of the auditory tasks.

title: Differentiation of negative event-related potentials in an auditory discrimination task.
abstract: Several different negative potentials elicited in auditory perceptual tasks make spatially and temporally overlapping contributions to the scalp-recorded event-related potential. Frequent non-target tones in a 2-stimulus oddball pitch discrimination task, when compared with the same stimuli in ignore or simple reaction time conditions, elicit a negative deflection with two peaks (NA1 and NA2) differing in their latency and topography from the exogenous N92-P156 deflections. Oddball tones, when compared with the frequent ones, elicit mismatch negativity (MMN) in both ignore and discrimination conditions; MMN displays a frontocentral-posterolateral polarity inversion. In the discrimination condition, MMN is followed by N2 and P3b; the former has a more central amplitude maximum than MMN, and no posterolateral polarity inversion. When the pitch discrimination task was made more difficult, there was no effect on NA1 or NA2, but the latency of MMN, N2, P3b, and reaction time all increased in parallel. It is hypothesized that MMN reflects the outcome of an automatic mismatch detection process, and that the subsequent processing of targets is related to the event of mismatch detection.

title: Frequency discrimination at different frequency levels as indexed by electrophysiological and behavioral measures.
abstract: The present study systematically compared the neural and behavioral accuracy of discriminating a frequency change ("deviant") in a repetitive tone ("standard") across a frequency range of 250-4000 Hz. The sound structure (pure sinusoidal vs. harmonically rich tones) and the magnitude of frequency change (2.5%, 5%, 10%, 20%) were also varied. The accuracy of neural frequency-change detector was determined by comparing the auditory event-related potentials (ERP) elicited by deviant and standard stimuli in the absence of attention. In a separate behavioral task, subjects were to indicate when they noticed a frequency change. The ranges of the across-subject means of ERP parameters across the conditions were: the mismatch negativity (MMN) amplitude -0.9 to -4.9 microV, latency 125-218 ms, the P3a amplitude 0.3-3.2 microV, latency 239-304 ms. The ERP latency was shortest for the standard-stimulus frequency from 1000 to 2000 Hz suggesting that automatic frequency discrimination was the most accurate in that range. The ERP latencies and amplitudes correlated with the hit rate (HR) and reaction time (RT), with highest correlation found between the MMN amplitude and the HR (r=0.8). The harmonical tones elicited MMN and P3a with shorter latencies and larger amplitudes, than did pure sinusoidal tones in all frequency bands. The results may have implication to pitch-perception theories.

title: The accuracy of sound duration representation in the human brain determines the accuracy of behavioural perception
abstract: In recent years, the links between neural activity and perception have been an area of interest in cognitive neuroscience. Combined psychophysiological and psychophysical experiments provide a new powerful tool for establishing the relationship between neural activity and perceptual performance. In animals, intracellular recordings combined with psychophysical detection indices have revealed that a particular neuron or set of neurons can play a critical role in the generation of a perceptual event, showing detection functions (referred to as neurometric functions) which are remarkably similar to psychophysical detection functions, or psychometric functions ( Parker & Newsome, (1998)  21, 227–277). As noninvasive techniques for recording neural activity are now available, studies combining neuroelectric and psychophysical measures in humans are sparse. In the present study, the accuracy of the human brain in detecting differences in sound duration and the subject's ability to perceive the same differences were tested by means of mismatch negativity (MMN) and the distance between the distributions of false alarms and hits (sensitivity index d′), respectively. It was found that the accuracy of the human auditory system to represent sound duration information is related to the duration context in which the sounds are heard, and that these contextual representations determine the accuracy of perception at the behavioural level.

title: Auditory frequency discrimination and event-related potentials.
abstract: Auditory stimulus blocks were presented to 6 subjects. 80% of the stimuli in each block were standards of 1000 Hz and 20% were deviants of either 1002 Hz, 1004 Hz, 1008 Hz, 1016 Hz or 1032 Hz, one deviant type in each block. The constant interstimulus interval was 1 sec and the order of the stimuli was randomized. The subject was instructed either to ignore the deviant stimuli (ignore condition) or to press a response key to them (discrimination condition). In the ignore condition, an ERP component called the mismatch negativity (MMN), with a peak latency of approximately 170 msec, was elicited by those deviants exceeding the discrimination threshold (1016 Hz and 1032 Hz) and also those at the threshold (1008 Hz) tended to elicit a small MMN. In the discrimination condition, in addition to MMN, another negative component, N2b, was elicited by the detected deviants. This component had a somewhat longer latency than, and its midline distribution was posterior to, the MMN. The present results are in line with the hypothesis according to which the MMN component reflects the activation of cerebral mechanisms of passive discrimination, those which cause us to become aware of occasional changes in unattended stimulus sequences. In the discrimination condition, N2b and the slow parietal positivity were dominant features of the ERPs elicited by the detected suprathreshold deviants. The data obtained at the discrimination threshold specifically associate the parietal positivity with becoming aware of stimulus change since those deviants which were detected elicited this positivity whereas there was none to those (physically identical) deviants which remained undetected.

title: Bottom-up influences on working memory: behavioral and electrophysiological distraction varies with distractor strength.
abstract: The present study investigates bottom-up effects serving the optimal balance between focusing attention on relevant information and distractibility by potentially significant events outside the focus of attention. We tested whether distraction, indicated by behavioral and event-related brain potential (ERP) measures, varies with the strength of task-irrelevant deviances. Twenty subjects performed a tone-duration discrimination task (200 or 400 ms sinusoidal tones presented equiprobably). The stimuli were presented with frequent standard (p = 0.84; 1000 Hz) or infrequent deviant (p = 0.16) pitch. These task-irrelevant pitch changes consisted in a frequency increase/decrease of 1%, 3%, 5%, or 10%. Each of them resulted in prolonged reaction times (RT) in the duration discrimination task and elicited the MMN, P3a, and RON components of the ERP. Importantly, these measures did increase as a function of pitch deviance. Separating the individual trials on the 1% deviation level into trials with and without RT prolongation, i.e., behavioral distraction effect, revealed that both subgroups had similar MMN, but P3a and RON were confined to the trials with RT prolongation. Results are interpreted within a model relating preattentive deviance detection, distraction, and working memory.

title: The time-course of auditory and visual distraction effects in a new crossmodal paradigm
abstract: Vision often dominates audition when attentive processes are involved (e.g., the ventriloquist effect), yet little is known about the relative potential of the two modalities to initiate a "break through of the unattended". The present study was designed to systematically compare the capacity of task-irrelevant auditory and visual events to withdraw attention from the other modality. Sequences of auditory and visual stimuli were presented with different amounts of temporal offset to determine the presence, strength, and time-course of attentional orienting and reorienting as well as their impact on task-related processing. One of the streams was task-relevant, while crossmodal distraction caused by unexpected events in the other stream was measured by impairments of behavioral task performance and by the N2, P3a, and reorienting negativity (RON) components of the event-related potential (ERP). Unexpected events in the visual modality proved to be somewhat more salient than those in the auditory modality, yet crossmodal interference caused by auditory stimuli was more pronounced. The visual modality was relatively constrained in terms of a critical time-range within which distraction effects could be elicited, while the impact of auditory stimuli on task-related processing extended over a longer time-range. These results are discussed in terms of functional differences between the auditory and visual modalities. Further applications of the new crossmodal protocol are deemed promising in view of the considerable size of the obtained distraction effects.

title: Cognitive control of involuntary attention and distraction in children and adolescents
abstract: The present study focused on the control of involuntary attentional orienting and distraction in children (6-8, 10-12 years) and adolescents (17-18 years). In an auditory distraction paradigm, pitch deviants interspersed in a sequence of standard sounds were presented. In the predictable condition, the type of sound (standard or deviant) was announced by a preceding visual cue. In the unpredictable condition, the cue was not informative with respect to the type of sound. Subjects performed a sound duration discrimination task and were instructed to attend the cues in order to avoid distraction. In the unpredictable condition, regular behavioral and ERP effects of change detection (Mismatch Negativity), attentional orienting (P3a) and distraction (prolonged reaction times) were observed. In the predictable condition, no modulation of Mismatch Negativity amplitude was observed, whereas the amplitude of P3a and reaction time prolongations in deviant trials were reduced in all age groups. Results suggest that even young children are able to voluntarily control involuntary attentional orienting and behavioral distraction. However, significant age effects were observed for the level of behavioral distraction and the selective utilization of the visual cues (reflected by P3b).

title: The development of involuntary and voluntary attention from childhood to adulthood: A combined behavioral and event-related potential study
abstract: This study investigated auditory involuntary and voluntary attention in children aged 6-8, 10-12 and young adults. The strength of distracting stimuli (20% and 5% pitch changes) and the amount of allocation of attention were varied.



In an auditory distraction paradigm event-related potentials (ERPs) and behavioral data were measured from subjects either performing a sound duration discrimination task or watching a silent video.



Pitch changed sounds caused prolonged reaction times and decreased hit rates in all age groups. Larger distractors (20%) caused stronger distraction in children, but not in adults. The amplitudes of mismatch negativity (MMN), P3a, and reorienting negativity (RON) were modulated by age and by voluntary attention. P3a was additionally affected by distractor strength. Maturational changes were also observed in the amplitudes of P1 (decreasing with age) and N1 (increasing with age). P2-modulation by voluntary attention was opposite in young children and adults.



Results suggest quantitative and qualitative changes in auditory voluntary and involuntary attention and distraction during development. The processing steps involved in distraction (pre-attentive change detection, attention switch, reorienting) are functional in children aged 6-8 but reveal characteristic differences to those of young adults. In general, distractibility as indicated by behavioral and ERP measures decreases from childhood to adulthood.



Behavioral and ERP markers for different processing stages involved in voluntary and involuntary attention reveal characteristic developmental changes from childhood to young adulthood.

title: Auditory distraction with different presentation rates: an event-related potential and behavioral study
abstract: The present study addresses the question of whether behavioral and electrophysiological effects obtained with the auditory distraction paradigm proposed by Schröger et al. 
Subjects had to discriminate the duration of tones. Occasionally, task-irrelevant frequency changes were used as distractors. In 3 experiments the stimulus onset asynchrony (SOA) was manipulated: In Experiment 1, SOAs of 1500, 2000 and 3000 ms were used in separate blocks; in Experiment 2, 5 different SOA of lengths between 1300 and 2500 ms were used within the blocks; in Experiment 3, a constant SOA of 1400 ms was compared with a SOA of random lengths between 1300 and 1500 ms. Performance data was analyzed for distraction effects. Event-related potentials (ERPs) were examined for deviance-related components, i.e. the mismatch negativity (MMN), the P3a and the re-orienting negativity (RON).



Behavioral distraction effects were obtained in all experimental conditions. The electrophysiological data show MMN, P3a and RON for the deviating tones in all experimental conditions as well.



The behavioral and electrophysiological deviance-related effects were not sensitive to the SOA manipulations. Therefore, the timing of the presentation can be adjusted to the proficiency level of the population to be tested without loosing the distraction effects.

title: Brain activity index of distractibility in normal school-age children
abstract: Children's attention is easily diverted from a current activity to a new event in the environment. This was indexed in school-age children by diminished performance speed and accuracy in a visual discrimination task caused by task-irrelevant novel sounds. Event-related brain potentials (ERPs) elicited by these distracting sounds showed a prominent positive deflection that was generated by brain processes associated with involuntary switching of attention to novel sounds. Recordings of the magnetoencephalographic (MEG) counterpart of this brain activity revealed a major bilateral generator source in the superior temporal cortex. However, ERP scalp distributions indicated also overlapping brain activity generated in other brain areas involved in involuntary attention switching. Moreover, differences in ERP amplitudes and in their correlations with the reaction times between younger (7-10 years) and older (11-13 years) children indicated developmental changes in attentional brain functions.

title: Neural Mechanisms of Involuntary Attention to Acoustic Novelty and Change
abstract: Behavioral and event-related brain potential (ERP) measures were used to elucidate the neural mechanisms of involuntary engagement of attention by novelty and change in the acoustic environment. The behavioral measures consisted of the reaction time (RT) and performance accuracy (hit rate) in a forced-choice visual RT task where subjects were to discriminate between odd and even numbers. Each visual stimulus was preceded by an irrelevant auditory stimulus, which was randomly either a standard tone (80), a slightly, higher deviant tone (10), or a natural, novel sound (10). Novel sounds prolonged the RT to successive visual stimuli by 17 msec as compared with the RT to visual stimuli that followed standard tones. Deviant tones, in turn, decreased the hit rate but did not significantly affect the RT. In the ERPs to deviant tones, the mismatch negativity (MMN), peaking at 150 msec, and a second negativity, peaking at 400 msec, could be observed. Novel sounds elicited an enhanced N1, with a probable overlap by the MMN, and a large positive P3a response with two different subcomponents: an early centrally dominant P3a, peaking at 230 msec, and a late P3a, peaking at 315 msec with a right-frontal scalp maximum. The present results suggest the involvement of two different neural mechanisms in triggering involuntary attention to acoustic novelty and change: a transient-detector mechanism activated by novel sounds and reflected in the N1 and a stimulus-change detector mechanism activated by deviant tones and novel sounds and reflected in the MMN. The observed differential distracting effects by slightly deviant tones and widely deviant novel sounds support the notion of two separate mechanisms of involuntary attention.

title: Behavioral and electrophysiological effects of task-irrelevant sound change: a new distraction paradigm.
abstract: A distraction paradigm was utilized that is suited to yield reliable auditory distraction on an individual level even with rather small frequency deviances (7%). Distraction to these tiny deviants was achieved by embedding task-relevant aspects and task-irrelevant, distracting aspects of stimulation into the same perceptual object. Event-related potential (ERP) and behavioral effects of this newly developed paradigm were determined. Subjects received tones that could be of short or long duration equiprobably. They were instructed to press a response button to long-duration tones (targets). In oddball blocks, tones could be of standard frequency or of low-probability (p=0.1), deviant frequency. The task-irrelevant frequency deviants elicited MMN, N2b, and P3a components, and caused impoverished behavioral performance to targets. The usage of tiny distractors permits an interpretation of auditory distraction in terms of attention switching due to a particular memory-related change-detection process. On the basis of the results from an additional condition in which tones were of 10 different frequencies (involving those frequencies which served as standard and deviant in oddball blocks), it is argued that one important prerequisite for linking the neural mechanisms reflected in change-related brain waves to behavioral distraction effects may be regarded as fulfilled. The robustness of the distraction effects to tiny deviations was confirmed in two control experiments.

title: Perception of Musical Intervals by Absolute Pitch Possessors
abstract: Previous studies have demonstrated that absolute pitch (AP) possessors can directly perceive the musical pitch quality (pitch class) of a tone presented in isolation. However, an isolated tone without musical context has no relevance to music, and AP ability should be examined in musically meaningful situations. In this study, AP possessors tried to identify the musical intervals between pairs of successive tones. The first tone (a reference) was either in-tune C according to the conventional pitch standard or out-of-tune C (a quarter-tone higher than standard C). The identification performance was less accurate and slower in the out-of-tune reference condition than in the in-tune condition. In contrast, AP nonpossessors showed no significant difference in performance in the two conditions, as predicted by the principle of equality under transposition. These results suggest that AP subjects tend to adhere to AP in relative pitch tasks, and that at least some AP listeners may have developed a strong dependence on AP at the sacrifice of relative pitch. AP may not have any advantage in music, in which relative pitch, not AP, is essential. Rather, AP may conflict with relative pitch and, in some cases, harm musical pitch processing.

title: The Attribution and Discounting of Perceptual Fluency: Preliminary Tests of a Perceptual Fluency/Attributional Model of the Mere Exposure Effect
abstract: Bornstein and D'Agostino (1990, 1992) hypothesized that the mere exposure effect results from a combination of two processes. First, an increase in perceptual fluency is induced by repeated exposure to a stimulus. Second, subjects attribute perceptual fluency effects to liking for a stimulus based on contextual cues provided by the experimenter. This paper describes two experiments that test predictions derived from the perceptual fluency/attributional model. In Experiment 1, the availability of information that allowed subjects to attribute perceptual fluency effects to the stimulus familarization procedure resulted in lower evaluative ratings of stimuli in a typical subliminal mere exposure effect experiment. In Experiment 2, the introduction of information that discouraged subjects from attributing perceptual fluency effects to the stimulus familiarization procedure resulted in more positive evaluative ratings of stimuli in a supraliminal mere exposure effect experiment. The theoretical implications of...

title: White matter plasticity in the corticospinal tract of musicians: A diffusion tensor imaging study
abstract: With the advent of diffusion tensor imaging (DTI), the study of plastic changes in white matter architecture due to long-term practice has attracted increasing interest. Professional musicians provide an ideal model for investigating white matter plasticity because of their early onset of extensive auditory and sensorimotor training. We performed fiber tractography and subsequent voxelwise analysis, region of interest (ROI) analysis, and detailed slicewise analysis of diffusion parameters in the corticospinal tract (CST) on 26 professional musicians and a control group of 13 participants. All analyses resulted in significantly lower fractional anisotropy (FA) values in both the left and the right CST in the musician group. Furthermore, a right-greater-than-left asymmetry of FA was observed regardless of group. In the musician group, diffusivity was negatively correlated with the onset of musical training in childhood. A subsequent median split into an early and a late onset musician group (median=7 years) revealed increased diffusivity in the CST of the early onset group as compared to both the late onset group and the controls. In conclusion, these DTI-based findings might indicate plastic changes in white matter architecture of the CST in professional musicians. Our results imply that training-induced changes in diffusion characteristics of the axonal membrane may lead to increased radial diffusivity as reflected in decreased FA values.

title: Benefits of multisensory learning
abstract: Studies of learning, and in particular perceptual learning, have focused on learning of stimuli consisting of a single sensory modality. However, our experience in the world involves constant multisensory stimulation. For instance, visual and auditory information are integrated in performing many tasks that involve localizing and tracking moving objects. Therefore, it is likely that the human brain has evolved to develop, learn and operate optimally in multisensory environments. We suggest that training protocols that employ unisensory stimulus regimes do not engage multisensory learning mechanisms and, therefore, might not be optimal for learning. However, multisensory-training protocols can better approximate natural settings and are more effective for learning.

title: Dynamics of cortico-subcortical cross-modal operations involved in audio-visual object detection in humans.
abstract: Very recently, a number of neuroimaging studies in humans have begun to investigate the question of how the brain integrates information from different sensory modalities to form unified percepts. Already, intermodal neural processing appears to depend on the modalities of inputs or the nature (speech/non-speech) of information to be combined. Yet, the variety of paradigms, stimuli and technics used make it difficult to understand the relationships between the factors operating at the perceptual level and the underlying physiological processes. In a previous experiment, we used event-related potentials to describe the spatio-temporal organization of audio-visual interactions during a bimodal object recognition task. Here we examined the network of cross-modal interactions involved in simple detection of the same objects. The objects were defined either by unimodal auditory or visual features alone, or by the combination of the two features. As expected, subjects detected bimodal stimuli more rapidly than either unimodal stimuli. Combined analysis of potentials, scalp current densities and dipole modeling revealed several interaction patterns within the first 200 micro s post-stimulus: in occipito-parietal visual areas (45-85 micro s), in deep brain structures, possibly the superior colliculus (105-140 micro s), and in right temporo-frontal regions (170-185 micro s). These interactions differed from those found during object identification in sensory-specific areas and possibly in the superior colliculus, indicating that the neural operations governing multisensory integration depend crucially on the nature of the perceptual processes involved.

title: Auditory-Visual Integration during Multimodal Object Recognition in Humans: A Behavioral and Electrophysiological Study
abstract: The aim of this study was (1) to provide behavioral evidence for multimodal feature integration in an object recognition task in humans and (2) to characterize the processing stages and the neural structures where multisensory interactions take place. Event-related potentials (ERPs) were recorded from 30 scalp electrodes while subjects performed a forced-choice reaction-time categorization task: At each trial, the subjects had to indicate which of two objects was presented by pressing one of two keys. The two objects were defined by auditory features alone, visual features alone, or the combination of auditory and visual features. Subjects were more accurate and rapid at identifying multimodal than unimodal objects. Spatiotemporal analysis of ERPs and scalp current densities revealed several auditory-visual interaction components temporally, spatially, and functionally distinct before 200 msec poststimulus. The effects observed were (1) in visual areas, new neural activities (as early as 40 msec poststimulus) and modulation (amplitude decrease) of the N185 wave to unimodal visual stimulus, (2) in the auditory cortex, modulation (amplitude increase) of subcomponents of the unimodal auditory N1 wave around 90 to 110 msec, and (3) new neural activity over the right fronto-temporal area (140 to 165 msec). Furthermore, when the subjects were separated into two groups according to their dominant modality to perform the task in unimodal conditions (shortest reaction time criteria), the integration effects were found to be similar for the two groups over the nonspecific fronto-temporal areas, but they clearly differed in the sensory-specific cortices, affecting predominantly the sensory areas of the nondominant modality. Taken together, the results indicate that multisensory integration is mediated by flexible, highly adaptive physiological processes that can take place very early in the sensory processing chain and operate in both sensory-specific and nonspecific cortical structures in different ways.