bluuebunny/crossref_metadata_2025 huggingface dataset:
Life‐Cycle Global Warming Impact of CFCs and CFC‐substitutes for Refrigeration
Authors: Papasavva Stella , Moomaw William R.
Published: May 2006

We have investigated the global warming potential (GWP) of CFC‐I I, CFC‐12, and their replacements, HCFC‐I23 and HFC‐I34a, based on a life‐cycle methodology for refrigeration. We have extended the definition of the total equivalent warming impact (TEWI), which considers the GWP (direct) and GWP (indirect) warming potential of each chemical compound, by adding the GWP (chemical production), GWP (recycling), and GWP (atmospheric breakdown products) for each chemical. We call the new index “life‐cycle warming impact” (LCWI).We find that the GWP (chemical production) contributes by no more than 1% to LCWI, and that the GWP (indirect) is highly dependent on refrigerator eficiency and the fuel mix of the electricity source used to operate the appliance. The GWP (atmospheric breakdown products) may also have a significant impact on LCWI.
Combining SFA and LCA
Authors: Tukker Arnold , Kleijn René , van Oers Lauran , Smeets Edith
Published: May 2006

This article describes a method that combines substance flow analysis (SFA) and life‐cycle assessment (LCA). It was used to provide a focus in the heated Swedish polyvinylchloride (PVC) debate. For Sweden's PVC chain, all emissions related to PVC were inventoried and translated into LCA‐theme scores. The theme scores were compared with total theme scores for all Swedish processes and were benchmarked on the basis of PVC's contribution to Sweden's gross national product (GNP). Mass flows oftwo PVC additives, lead and organotin, were compared with the total use of these metals in Sweden. PVC's contribution to global warming, smog formation, and waste volume was equal to or less than the benchmark. After implementation of planned measures, emissions of the toxic substances dioxins, mercury, and lead will be below the benchmark. We recommend that the Swedish PVC debate concentrate on the uncertainties of the effects of phthalates, small process emissions of persistent chlorinated substances (PBTs), lead and organotin in landfilled PVC, and emissions from PVC in accidental fire
Comments on “The Grand Objectives” by Thomas E. Graedel
Authors: Craig Paul P.
Published: May 2006

In “The Grand Objectives: A Framework for Prioritized Grouping of Environmental Concerns in Life‐Cycle Assessment”. Thomas Graedel (1997) proposed an elegant schema for prioritizing environmental concerns. It operates at three levels: grand objectives, environmental concerns, and targeted activities. I argue that consensus is most likely on the first and third levels, but that the middle level, environmental concerns, is more problematic. Even among individuals who agree on general societal directions, strong differences of views can occur regarding specific technologies. I illustrate by applying Graedel's system to his “radionuclide” category, under his first grand objective (human species extinction). I use the example of nuclear waste to illustrate how values are inextricably involved at the “environmental concerns” level. My analysis suggests ways to enhance the utility of Graedel's useful system.
Environmental Security as a Case Study in Industrial Ecology
Authors: Allenby Brad
Published: May 2006

Environmental security is the integration of environmental and national security considerations at a national policy level. It is a relatively new and still somewhat contentious concept, although in some countries, such as the United States, it is increasingly being embedded in traditional security and foreign policy institutions. It is of interest to the industrial ecologist for several reasons. First, from the methodological perspective, environmental security issues are frequently complex, multidisciplinary, and multiscalar in both temporal and geographic dimensions. They are thus good opportunities to apply existing industrial ecology tools such as industrial metabolism stock and flow studies, as well as to support the development of new industrial ecology methods. Second, environmental security offers an important case study of an important fundamental industrial ecology dynamic: the movement of environment from overhead to strategic for society. This process occurs at many different scales, from implementation of design for environment methodologies within firms to integration of environmental and trade considerations in the World Trade Organization; and it is important for the industrial ecologist to begin to understand its underlying dynamics. Finally, national security is the quintessential raison d'etre of the national state. Accordingly, the integration of environmental considerations into national security policies and institutions, using industrial ecology methodologies and patterns of analysis, is a significant validation of the field.
Society's Metabolism
Authors: Fischer‐Kowalski Marina
Published: May 2006

In this article, we inquire into the intellectual history ofthe application of the biological concept of metabolism to social systems‐not as a metaphor; but as a material and energetic process within the economy and society vis‐A‐vis various natural systems. The paper reviews several scientific traditions that may contribute to such a view, including biology and ecology, social theory, cultural anthropology, and social geography It assembles widely scattered approaches dating from the 1860s onward and shows how they prepare the ground for the pioneers of “industrial metabolism” in the late 1960s. In connection to varying political perspedives, metabolism gradually takes shape as a powerful interdisciplinary concept It will take another 25 years before this approach becomes one of the most important paradigms for the empirical analysis of the society‐nature‐interaction across various disciplines. This later period will be the subject of part II of this literature review
The Life Cycle of Chlorine, Part III
Authors: Ayres Robert U.
Published: May 2006

In the two previous articles in this series we reviewed the major processes of chlorine production (Part I) and its intermediate uses and waste products in the production of other chemicals (Part 11). In this article I consider some of the final applications of chlorine (e.g., for water treatment and pulp bleaching) and the uses of the most important chlorinated compounds such as solvents, chlorofluorocarbons, and the plastic polyvinyl chloride in the industrial economy. I summarize known evidence regarding their environmental fates. The special case of persistent long‐lived toxic compounds (e.g., pesticides) will be discussed in a subsequent article.
Site‐Dependent Life‐Cycle Impact Assessment of Acidification
Authors: Potting José , Schöpp Wolfgang , Blok Kornelis , Hauschild Michael
Published: May 2006

The lack of spatial differentiation in current life‐cycle impact assessment (LCIA) affects the relevance of the assessed impact. This article first describes a framework for constructing factors relating the region of emission to the acidifying impact on its deposition areas. Next, these factors are established for 44 European regions with the help of the RAINS model, an integrated assessment model that combines information on regional emission levels with information on long‐range atmospheric transport to estimate patterns of deposition and concentration for comparison with critical loads and thresholds for acidification, eutrophication via air; and tropospheric ozone formation. The application of the acidification factors in LCIA is very straightforward. The only additional data required, the geographical site of the emission, is generally provided by current life‐cycle inventory analysis. The acidification factors add resolving power of a factor of 1,000 difference between the highest and lowest ratings, while the combined uncertainties in the RAINS model are canceled out to a large extent in the acidification factors as a result of the large number of ecosystems they cover The framework presented is also suitable for establishing similar factors for eutrophication and tropospheric ozone formation for regions outside Europe as well.
Books
Authors: DeCicco John
Published: May 2006

Industrial Ecology of the Automobile: A Lifecycle Perspective, by Gregory A. Keoleian, Krishnendu Kar, Michelle M. Manion, and Jonathan W. Bulkley

Industrial Ecology and the Automobile, by Thomas E. Graedel and Braden R. Allenby
Activity‐Based Environmental Inventory Allocation
Authors: Stuart Julie Ann , Turbini Laura J. , Ammons Jane C.
Published: May 2006

This article presents a generic method to assist product and process designers in measuring resource use and environmental discharges based on the relationships between process flow inputs and outputs and their activity levels. It combines activity‐based costing from conventional accounting with life‐cycle inventories. The method is demonstrated on four electronic assembly product and process designs. The demonstration exhibits the disaggregation and allocation of costs and effluents from various manufacturing operations. This activity‐based environmental allocation approach may be integrated with inventory analysis‐the first step in full and streamlined life‐cycle assessments, design for environment evaluation methods, environmental management activities, and new production planning models that consider environmental impacts.
Books
Authors: Helms Susan , Goldstein James
Published: May 2006

Remanufacturing: The Ultimate Form of Recycling, by Rolf Steinhilper.

The Remanufacturing Industry: Hidden Giant by Robert T. Lund.
Book:
Authors: Heaton George R.
Published: May 2006

Technology and Global Change, by Arnulf Grübler

Technological Trajectories and the Human Environment, ed. by Jesse Ausubel and H. Dale Langford
Commentry: Operatic Modernism
Authors: Schorske Carl E.
Published: May 2006

The problem with deªning operatic Modernism is that, unlike Modernism in architecture, it did not have a single language that united the movement across Europe. In opera there was certainly an organizational component, notably represented by the Kroll Opera House in Berlin. But in musical terms, we have to accept two kinds of Modernism, represented by Rosenkavalier and Wozzeck.
The Neurophysiological Basis of the Auditory Continuity Illusion: A Mismatch Negativity Study
Authors: Micheyl Christophe , Carlyon Robert P. , Shtyrov Yury , Hauk Olaf , Dodson Tara , Pullvermüller Friedemann
Published: May 2006

A sound turned off for a short moment can be perceived as continuous if the silent gap is filled with noise. The neural mechanisms underlying this “continuity illusion” were investigated using the mismatch negativity (MMN), an eventrelated potential reflecting the perception of a sudden change in an otherwise regular stimulus sequence. The MMN was recorded in four conditions using an oddball paradigm. The standards consisted of 500-Hz, 120-msec tone pips that were either physically continuous (Condition 1) or were interrupted by a 40-msec silent gap (Condition 2). The deviants consisted of the interrupted tone, but with the silent gap filled by a burst of bandpass-filtered noise. The noise either occupied the same frequency region as the tone and elicited the continuity illusion (Conditions 1a and 2a), or occupied a remote frequency region and did not elicit the illusion (Conditions 1b and 2b). We predicted that, if the continuity illusion is determined before MMN generation, then, other things being equal, the MMN should be larger in conditions where the deviants are perceived as continuous and the standards as interrupted or vice versa, than when both were perceived as continuous or both interrupted. Consistent with this prediction, we observed an interaction between standard type and noise frequency region, with the MMN being larger in Condition 1a than in Condition 1b, but smaller in Condition 2a than in Condition 2b. Because the subjects were instructed to ignore the tones and watch a silent movie during the recordings, the results indicate that the continuity illusion can occur outside the focus of attention. Furthermore, the latency of the MMN (less than approximately 200 msec postdeviance onset) places an upper limit on the stage of neural processing responsible for the illusion.
Musician Children Detect Pitch Violations in Both Music and Language Better than Nonmusician Children: Behavioral and Electrophysiological Approaches
Authors: Magne Cyrille , Schön Daniele , Besson Mireille
Published: May 2006

The idea that extensive musical training can influence processing in cognitive domains other than music has received considerable attention from the educational system and the media. Here we analyzed behavioral data and recorded event-related brain potentials (ERPs) from 8-year-old children to test the hypothesis that musical training facilitates pitch processing not only in music but also in language. We used a parametric manipulation of pitch so that the final notes or words of musical phrases or sentences were congruous, weakly incongruous, or strongly incongruous. Musician children outperformed nonmusician children in the detection of the weak incongruity in both music and language. Moreover, the greatest differences in the ERPs of musician and nonmusician children were also found for the weak incongruity: whereas for musician children, early negative components developed in music and late positive components in language, no such components were found for nonmusician children. Finally, comparison of these results with previous ones from adults suggests that some aspects of pitch processing are in effect earlier in music than in language. Thus, the present results reveal positive transfer effects between cognitive domains and shed light on the time course and neural basis of the development of prosodic and melodic processing.
A Large-scale Neurocomputational Model of Task-oriented Behavior Selection and Working Memory in Prefrontal Cortex
Authors: Chadderdon George L. , Sporns Olaf
Published: May 2006

The prefrontal cortex (PFC) is crucially involved in the executive component of working memory, representation of task state, and behavior selection. This article presents a large-scale computational model of the PFC and associated brain regions designed to investigate the mechanisms by which working memory and task state interact to select adaptive behaviors from a behavioral repertoire. The model consists of multiple brain regions containing neuronal populations with realistic physiological and anatomical properties, including extrastriate visual cortical regions, the inferotemporal cortex, the PFC, the striatum, and midbrain dopamine (DA) neurons. The onset of a delayed match-to-sample or delayed nonmatch-to-sample task triggers tonic DA release in the PFC causing a switch into a persistent, stimulus-insensitive dynamic state that promotes the maintenance of stimulus representations within prefrontal networks. Other modeled prefrontal and striatal units select cognitive acceptance or rejection behaviors according to which task is active and whether prefrontal working memory representations match the current stimulus. Working memory task performance and memory fields of prefrontal delay units are degraded by extreme elevation or depletion of tonic DA levels. Analyses of cellular and synaptic activity suggest that hyponormal DA levels result in increased prefrontal activation, whereas hypernormal DA levels lead to decreased activation. Our simulation results suggest a range of predictions for behavioral, single-cell, and neuroimaging response data under the proposed task set and under manipulations of DA concentration.
Fractionating the Left Frontal Response to Tools: Dissociable Effects of Motor Experience and Lexical Competition
Authors: Kan Irene P. , Kable Joseph W. , Van Scoyoc Amanda , Chatterjee Anjan , Thompson-Schill Sharon L.
Published: May 2006

A number of theories about the evolution of language posit a close (and perhaps causal) relationship between tool use and speech. Consistent with this idea, neuroimaging studies have found that tool knowledge retrieval activates not only a region of the left premotor cortex involved in hand action, but also an adjacent region that is typically described as a language center. We examined whether this pattern of activation is best described as the result of a single process, related to both action and language, or the result of two independent processes. We identified two distinct neural components that jointly contribute to this response: a posterior region centered in the premotor cortex, which responds to motor knowledge retrieval, and an anterior region centered in the left frontal operculum, which responds to lexical competition. Crucial to the interpretation of the premotor response, individual variation in motor experience was highly correlated with the magnitude of the response in the premotor cortex, but not in the prefrontal cortex.
fMRI of Past Tense Processing: The Effects of Phonological Complexity and Task Difficulty
Authors: Desai Rutvik , Conant Lisa L. , Waldron Eric , Binder Jeffrey R.
Published: May 2006

The generation of regular and irregular past tense verbs has been an important issue in cognitive science and has been used to advance different models of the organization of language in the brain. The dual-system view holds that the regular past tense forms are generated by a rule while irregular forms are retrieved from memory. The single-system view, on the other hand, holds that both forms are generated by a single integrated system and differ only in their reliance on factors such as phonology and semantics. We conducted an event-related fMRI study to examine the activation patterns associated with the generation and reading of regular and irregular past tense forms, in addition to the reading of their stems. Regular and irregular past tense generation activated similar brain regions compared to the reading of their respective stems. The areas activated more for irregular generation compared to regular generation included inferior frontal, precentral, and parietal regions bilaterally. This activation can be interpreted as reflecting the greater attentional and response selection demands of irregular generation. Compared to irregular generation, regular generation activated a small region in the left superior temporal gyrus when the regular and irregular past tense forms were mismatched on phonological complexity. No areas were more activated for regulars than irregulars when the past tense forms were matched on this variable. This suggests that the activation specific to regulars was related to the higher phonological complexity of their past tense forms rather than to their generation. A contrast of the reading of regular and irregular past tense forms was consistent with this hypothesis. These results support a single-system account of past tense generation.
Objects Are Highlighted by Spatial Attention
Authors: Martínez A. , Teder-Sälejärvi W. , Vazquez M. , Molholm S. , Foxe J. J. , Javitt D. C. , Di Russo F. , Worden M. S. , Hillyard S. A.
Published: May 2006

Selective attention may be focused upon a region of interest within the visual surroundings, thereby improving the perceptual quality of stimuli at that location. It has been debated whether this spatially selective mechanism plays a role in the attentive selection of whole objects in a visual scene. The relationship between spatial and object-selective attention was investigated here through recordings of event-related brain potentials (ERPs) supplemented with functional magnetic brain imaging (fMRI). Subjects viewed a display consisting of two bar-shaped objects and directed attention to sequences of stimuli (brief corner offsets) at one end of one of the bars. Unattended stimuli belonging to the same object as the attended stimuli elicited spatiotemporal patterns of neural activity in the visual cortex closely resembling those elicited by the attended stimuli themselves, albeit smaller in amplitude. This enhanced neural activity associated with object-selective attention was localized by use of ERP dipole modeling and fMRI to the lateral occipital extrastriate cortex. We conclude that object-selective attention shares a common neural mechanism with spatial attention that entails the facilitation of sensory processing of stimuli within the boundaries of an attended object.
Implicit Learning–Explicit Knowing: A Role for Sleep in Memory System Interaction
Authors: Fischer Stefan , Drosopoulos Spyridon , Tsen Jim , Born Jan
Published: May 2006

There is evidence that sleep supports the enhancement of implicit as well as explicit memories (i.e., two memory systems that during learning normally appear to act together). Here, employing a serial reaction time task (SRTT) paradigm, we examined the question whether sleep can provide explicit knowledge on an implicitly acquired skill. At learning, young healthy subjects (n = 20) were first trained on the SRTT. Then, implicit knowledge was assessed on two test blocks, in which grammatically incorrect target positions were occasionally interspersed by the difference in reaction times between grammatically correct and incorrect target positions. To assess explicit sequence knowledge, thereafter subjects performed on a generation task in which they were explicitly instructed to predict the sequential target positions. In half the subjects, learning took place before a 9-hour retention interval filled with nocturnal sleep (sleep group), in the other half, the retention interval covered a 9-hour period of daytime wakefulness (wake group). At subsequent retesting, both testing on the generation task and the SRTT test blocks was repeated. At learning before the retention interval, subjects displayed significant implicit sequence knowledge which was comparable for the sleep and wake groups. Moreover, both groups did not display any explicit sequence knowledge as indicated by a prediction performance not differing from chance on the generation task. However, at retesting, there was a distinct gain in explicit knowledge in the subjects who had slept in the retention interval, whereas generation task performance in the wake group remained at chance level. SRTT performance in the test blocks at retesting did not indicate any further gain in skill (i.e., unchanged reaction time differences between grammatically correct and incorrect target positions) independently of whether subjects had slept or remained awake after learning. Our results indicate a selective enhancement of explicit memory formation during sleep. Because before sleep subjects only had implicit knowledge on the sequence of target transitions, these data point to an interaction between implicit and explicit memory systems during sleep-dependent off-line learning.
fMRI Evidence for a Three-Stage Model of Deductive Reasoning
Authors: Fangmeier Thomas , Knauff Markus , Ruff Christian C. , Sloutsky Vladimir
Published: May 2006

Deductive reasoning is fundamental to science, human culture, and the solution of problems in daily life. It starts with premises and yields a logically necessary conclusion that is not explicit in the premises. Here we investigated the neurocognitive processes underlying logical thinking with event-related functional magnetic resonance imaging. We specifically focused on three temporally separable phases: (1) the premise processing phase, (2) the premise integration phase, and (3) the validation phase in which reasoners decide whether a conclusion logically follows from the premises. We found distinct patterns of cortical activity during these phases, with initial temporo-occipital activation shifting to the prefrontal cortex and then to the parietal cortex during the reasoning process. Activity in these latter regions was specific to reasoning, as it was significantly decreased during matched working memory problems with identical premises and equal working memory load.
Voluntary Selection of Task Sets Revealed by Functional Magnetic Resonance Imaging
Authors: Forstmann Birte U. , Brass Marcel , Koch Iring , von Cramon D. Yves
Published: May 2006

In everyday life, we have to selectively adapt our behavior to different situations and tasks. In cognitive psychology, such adaptive behavior can be investigated with the task-switching paradigm. However, in contrast to everyday life, in experiments participants are unequivocally told which task to perform. The present functional magnetic resonance imaging (fMRI) study was set out to investigate processes that are relevant when participants can decide by their own which task to perform. The number of tasks to choose from was varied between a forced condition (no choice) and two voluntary selection conditions (two or three choices). We expected to find prolonged reaction times as well as higher activations within the midcingulate cortex for the choice conditions compared to the no-choice condition. The fMRI results revealed a significant activation difference for the choice conditions versus the no-choice condition. For the choice contrast, activation was found in the rostral cingulate zone (RCZ) as well as the superior parietal lobule and the posterior part of the intraparietal sulcus. These activations revealed no selection-specific difference between three and two choices. Finally, a post hoc analysis showed that the activation in the RCZ is not associated with higher task-dependent response conflict when participants can select a task set. Taken together, these findings indicate that distinct brain areas are involved in the voluntary selection of abstract task set information.
Neurophysiological Correlates of Emotion Regulation in Children and Adolescents
Authors: Lewis Marc D. , Lamm Connie , Segalowitz Sidney J. , Stieben Jim , Zelazo Philip David
Published: May 2006

Psychologists consider emotion regulation a critical developmental acquisition. Yet, there has been very little research on the neural underpinnings of emotion regulation across childhood and adolescence. We selected two ERP components associated with inhibitory control—the frontal N2 and frontal P3. We recorded these components before, during, and after a negative emotion induction, and compared their amplitude, latency, and source localization over age. Fifty-eight children 5–16 years of age engaged in a simple go/no-go procedure in which points for successful performance earned a valued prize. The temporary loss of all points triggered negative emotions, as confirmed by self-report scales. Both the frontal N2 and frontal P3 decreased in amplitude and latency with age, consistent with the hypothesis of increasing cortical efficiency. Amplitudes were also greater following the emotion induction, only for adolescents for the N2 but across the age span for the frontal P3, suggesting different but overlapping profiles of emotion-related control mechanisms. No-go N2 amplitudes were greater than go N2 amplitudes following the emotion induction at all ages, suggesting a consistent effect of negative emotion on mechanisms of response inhibition. No-go P3 amplitudes were also greater than go P3 amplitudes and they decreased with age, whereas go P3 amplitudes remained low. Finally, source modeling indicated a developmental decline in central-posterior midline activity paralleled by increasing activity in frontal midline regions suggestive of the anterior cingulate cortex. Negative emotion induction corresponded with an additional right ventral prefrontal or temporal generator beginning in middle childhood.
Executive “Brake Failure” following Deactivation of Human Frontal Lobe
Authors: Chambers Christopher D. , Bellgrove Mark A. , Stokes Mark G. , Henderson Tracy R. , Garavan Hugh , Robertson Ian H. , Morris Adam P. , Mattingley Jason B.
Published: May 2006

In the course of daily living, humans frequently encounter situations in which a motor activity, once initiated, becomes unnecessary or inappropriate. Under such circumstances, the ability to inhibit motor responses can be of vital importance. Although the nature of response inhibition has been studied in psychology for several decades, its neural basis remains unclear. Using transcranial magnetic stimulation, we found that temporary deactivation of the pars opercularis in the right inferior frontal gyrus selectively impairs the ability to stop an initiated action. Critically, deactivation of the same region did not affect the ability to execute responses, nor did it influence physiological arousal. These findings confirm and extend recent reports that the inferior frontal gyrus is vital for mediating response inhibition.
Effects of Musical Expertise and Boundary Markers on Phrase Perception in Music
Authors: Neuhaus Christiane , Knösche Thomas R. , Friederici Angela D.
Published: May 2006

A neural correlate for phrase boundary perception in music has recently been identified in musicians. It is called music closure positive shift (“music CPS”) and has an equivalent in the perception of speech (“language CPS”). The aim of the present study was to investigate the influence of musical expertise and different phrase boundary markers on the music CPS, using event-related brain potentials (ERPs) and event-related magnetic fields (ERFs). Musicians and nonmusicians were tested while listening to binary phrased melodies. ERPs and ERFs of both subject groups differed considerably from each other. Phrased melody versions evoked an electric CPS and a magnetic CPSm in musicians, but an early negativity and a less pronounced CPSm in nonmusicians, suggesting different perceptual strategies for both subject groups. Musicians seem to process musical phrases in a structured manner similar to language. Nonmusicians, in contrast, are thought to detect primarily discontinuity in the melodic input. Variations of acoustic cues in the vicinity of the phrase boundary reveal that the CPS is influenced by a number of parameters that are considered to indicate phrasing in melodies: pause length, length of the last tone preceding the pause, and harmonic function of this last tone. This is taken as evidence that the CPS mainly reflects higher cognitive processing of phrasing, rather than mere perception of pauses. Furthermore, results suggest that the ERP and MEG methods are sensitive to different aspects within phrase perception. For both subject groups, qualitatively different ERP components (CPS and early negativity) seem to reflect a top-down activation of general but different phrasing schemata, whereas quantitatively differing MEG signals appear to reflect gradual differences in the bottom-up processing of acoustic boundary markers.
Specialized Face Perception Mechanisms Extract Both Part and Spacing Information: Evidence from Developmental Prosopagnosia
Authors: Yovel Galit , Duchaine Brad
Published: May 2006

It is well established that faces are processed by mechanisms that are not used with other objects. Two prominent hypotheses have been proposed to characterize how information is represented by these special mechanisms. The spacing hypothesis suggests that face-specific mechanisms primarily extract information about spacing among parts rather than information about the shape of the parts. In contrast, the holistic hypothesis suggests that faces are processed as nondecomposable wholes and, therefore, claims that both parts and spacing among them are integral aspects of face representation. Here we examined these hypotheses by testing a group of developmental prosopagnosics (DPs) who suffer from deficits in face recognition. Subjects performed a face discrimination task with faces that differed either in the spacing of the parts but not the parts (spacing task), or in the parts but not the spacing of the parts (part task). Consistent with the holistic hypothesis, DPs showed lower performance than controls on both the spacing and the part tasks, as long as salient contrast differences between the parts were minimized. Furthermore, by presenting similar spacing and part tasks with houses, we tested whether face-processing mechanisms are specific to faces, or whether they are used to process spacing information from any stimulus. DPs' normal performance on the tasks of two houses indicates that their deficit does not result from impairment in a general-purpose spacing mechanism. In summary, our data clearly support face-specific holistic hypothesis by showing that face perception mechanisms extract both part and spacing information.
Effects of Aging on BOLD fMRI during Prosaccades and Antisaccades
Authors: Raemaekers M. , Vink M. , van den Heuvel M. P. , Kahn R. S. , Ramsey N. F.
Published: May 2006

Age affects the ability to inhibit saccadic eye movements. According to current theories, this may be associated with age-induced neurophysiological changes in the brain and with compensatory activation in frontal brain areas. In the present study, the effects of aging are assessed on brain systems that subserve generation and inhibition of saccadic eye movements. For this purpose, an event-related functional magnetic resonance imaging design was used in adults covering three age ranges (18–30, 30–55, and 55–72 years). Group differences were controlled for task performance. Activity associated with saccadic inhibition was represented by the contrast between prosaccade and antisaccade activation. The tasks activated well-documented networks of regions known to be involved in generation and inhibition of saccadic eye movements. There was an age-related shift in activity from posterior to frontal brain regions after young adulthood. In addition, old adults demonstrated an overall reduction in the blood oxygenation level dependent (BOLD) signal in the visual and oculomotor system. Age, however, did not affect saccade inhibition activity. Mid and old adults appear to increase frontal activation to maintain performance even during simple prosaccades. The global reduction of the BOLD response in old adults could reflect a reduction in neural activity, as well as changes in the neuronal-vascular coupling. Future research should address the impact of altered vascular dynamics on neural activation and the BOLD signal.
Electrophysiological Evidence of the Capture of Visual Attention
Authors: Hickey Clayton , McDonald John J. , Theeuwes Jan
Published: May 2006

We investigated the ability of salient yet task-irrelevant stimuli to capture attention in two visual search experiments. Participants were presented with circular search arrays that contained a highly salient distractor singleton defined by color and a less salient target singleton defined by form. A component of the event-related potential called the N2pc was used to track the allocation of attention to lateralized positions in the arrays. In Experiment 1, a lateralized distractor elicited an N2pc when a concurrent target was presented on the vertical meridian and thus could not elicit lateralized components such as the N2pc. A similar distractor-elicited N2pc was found in Experiment 2, which was conducted to rule out certain voluntary search strategies. Additionally, in Experiment 2 both the distractor and the target elicited the N2pc component when the two stimuli were presented on opposite sides of the search array. Critically, the distractor-elicited N2pc preceded the target-elicited N2pc on these trials. These results demonstrate that participants shifted attention to the target only after shifting attention to the more salient but task-irrelevant distractor. This pattern of results is in line with theories of attention in which stimulus-driven control plays an integral role.
Reduced Suppression or Labile Memory? Mechanisms of Inefficient Filtering of Irrelevant Information in Older Adults
Authors: Fabiani Monica , Low Kathy A. , Wee Emily , Sable Jeffrey J. , Gratton Gabriele
Published: May 2006

Cognitive aging theories emphasize the decrease in efficiency of inhibitory processes and attention control in normal aging, which, in turn, may result in reduction of working memory function. Accordingly, some of these age-related changes may be due to faster sensory memory decay or to inefficient filtering of irrelevant sensory information (sensory gating). Here, event-related brain potentials and the event-related optical signal were recorded in younger and older adults passively listening to tone trains. To determine whether age differentially affects decay of sensory memory templates over short intervals, trains were separated by delays of either 1 or 5 sec. To determine whether age affects the suppression of responses to unattended repeated stimuli, we evaluated the brain activity elicited by successive train stimuli. Some trains started with a shorter-duration stimulus (deviant trains). Results showed that both electrical and optical responses to tones were more persistent with repeated stimulation in older adults than in younger adults, whereas the effects of delay were similar in the two groups. A mismatch negativity (MMN) was elicited by the first stimulus in deviant trains. This MMN was larger for 1- than 5-sec delay, but did not differ across groups. These data suggest that age-related changes in sensory processing are likely due to inefficient filtering of repeated information, rather than to faster sensory memory decay. This inefficient filtering may be due to, or interact with, reduced attention control. Furthermore, it may increase the noise levels in the information processing system and thus contribute to problems with working memory and speed of processing.
Syntactic and Semantic Modulation of Neural Activity during Auditory Sentence Comprehension
Authors: Humphries Colin , Binder Jeffrey R. , Medler David A. , Liebenthal Einat
Published: May 2006

In previous functional neuroimaging studies, left anterior temporal and temporal-parietal areas responded more strongly to sentences than to randomly ordered lists of words. The smaller response for word lists could be explained by either (1) less activation of syntactic processes due to the absence of syntactic structure in the random word lists or (2) less activation of semantic processes resulting from failure to combine the content words into a global meaning. To test these two explanations, we conducted a functional magnetic resonance imaging study in which word order and combinatorial word meaning were independently manipulated during auditory comprehension. Subjects heard six different stimuli: normal sentences, semantically incongruent sentences in which content words were randomly replaced with other content words, pseudoword sentences, and versions of these three sentence types in which word order was randomized to remove syntactic structure. Effects of syntactic structure (greater activation to sentences than to word lists) were observed in the left anterior superior temporal sulcus and left angular gyrus. Semantic effects (greater activation to semantically congruent stimuli than either incongruent or pseudoword stimuli) were seen in widespread, bilateral temporal lobe areas and the angular gyrus. Of the two regions that responded to syntactic structure, the angular gyrus showed a greater response to semantic structure, suggesting that reduced activation for word lists in this area is related to a disruption in semantic processing. The anterior temporal lobe, on the other hand, was relatively insensitive to manipulations of semantic structure, suggesting that syntactic information plays a greater role in driving activation in this area.
Attentional Modulation in the Detection of Irrelevant Deviance: A Simultaneous ERP/fMRI Study
Authors: Sabri M. , Liebenthal E. , Waldron E. J. , Medler D. A. , Binder J. R.
Published: May 2006

Little is known about the neural mechanisms that control attentional modulation of deviance detection in the auditory modality. In this study, we manipulated the difficulty of a primary task to test the relation between task difficulty and the detection of infrequent, task-irrelevant deviant (D) tones (1300 Hz) presented among repetitive standard (S) tones (1000 Hz). Simultaneous functional magnetic resonance imaging (fMRI)/event-related potentials (ERPs) were recorded from 21 subjects performing a two-alternative forced-choice duration discrimination task (short and long tones of equal probability). The duration of the short tone was always 50 msec. The duration of the long tone was 100 msec in the easy task and 60 msec in the difficult task. As expected, response accuracy decreased and response time (RT) increased in the difficult compared with the easy task. Performance was also poorer for D than for S tones, indicating distraction by task-irrelevant frequency information on trials involving D tones. In the difficult task, an amplitude increase was observed in the difference waves for N1 and P3a, ERP components associated with increased attention to deviant sounds. The mismatch negativity (MMN) response, associated with passive deviant detection, was larger in the easy task, demonstrating the susceptibility of this component to attentional manipulations. The fMRI contrast D > S in the difficult task revealed activation on the right superior temporal gyrus (STG) and extending ventrally into the superior temporal sulcus, suggesting this region's involvement in involuntary attention shifting toward unattended, infrequent sounds. Conversely, passive deviance detection, as reflected by the MMN, was associated with more dorsal activation on the STG. These results are consistent with the view that the dorsal STG region is responsive to mismatches between the memory trace of the standard and the incoming deviant sound, whereas the ventral STG region is activated by involuntary shifts of attention to task-irrelevant auditory features.
Negative Priming in a Numerical Piaget-like Task as Evidenced by ERP
Authors: Daurignac Elsa , Houdé Olivier , Jouvent Roland
Published: May 2006

Inhibition is a key executive function in adults and children for the acquisition and expression of cognitive abilities. Using event-related potentials in a priming adaptation of a Piaget-like numerical task taken from developmental psychology, we report a negative priming effect in adults measured just after the cognitive inhibition of a misleading strategy, the visuospatial length-equals-number bias. This effect was determined in the N200 information processing stage through increased N200 amplitude. We show here that for accuracy in numerical quantification, the adult brain still had to control the childlike cognition biases that are stored in a kind of “developmental memory.”
Where and When the Anterior Cingulate Cortex Modulates Attentional Response: Combined fMRI and ERP Evidence
Authors: Crottaz-Herbette S. , Menon V.
Published: May 2006

Attentional control provides top-down influences that allow task-relevant stimuli and responses to be processed preferentially. The anterior cingulate cortex (ACC) plays an important role in attentional control, but the spatiotemporal dynamics underlying this process is poorly understood. We examined the activation and connectivity of the ACC using functional magnetic resonance imaging (fMRI) along with fMRI-constrained dipole modeling of event-related potentials (ERPs) obtained from subjects who performed auditory and visual oddball attention tasks. Although attention-related responses in the ACC were similar in the two modalities, effective connectivity analyses showed modality-specific effects with increased ACC influences on the Heschl and superior temporal gyri during auditory task and on the striate cortex during visual task. Dipole modeling of ERPs based on source locations determined from fMRI activations showed that the ACC was the major generator of N2b-P3a attention-related components in both modalities, and that primary sensory regions generated a small mismatch signal about 50 msec prior to feedback from the ACC and a large signal 60 msec after feedback from the ACC. Taken together, these results provide converging neuroimaging and electrophysiological evidence for top-down attentional modulation of sensory processing by the ACC. Our findings suggest a model of attentional control based on dynamic bottom-up and top-down interactions between the ACC and primary sensory regions.
Context Modulates Early Stimulus Processing when Resolving Stimulus-response Conflict
Authors: Scerif Gaia , Worden Michael S. , Davidson Matthew , Seiger Liat , Casey B. J.
Published: May 2006

When responding to stimuli in our environment, the presence of multiple items associated with task-relevant responses affects both ongoing response selection and subsequent behavior. Computational modeling of conflict monitoring and neuroimaging data predict that the recent context of response competition will bias the selection of certain stimuli over others very early in the processing stream through increased focal spatial attention. We used high-density EEG to test this hypothesis and to investigate the contextual effects on nonspatial, early stimulus processing in a modified flanker task. Subjects were required to respond to a central arrow and to ignore potentially conflicting information from flanking arrows in trials preceded by a series of either compatible or incompatible trials. On some trials, we presented the flanking arrows in the absence of the central target. The visual P1 component was selectively enhanced only for incompatible trials when preceded by incompatible ones, suggesting that contextual effects depend on feature-based processing, and not only simple enhancement of the target location. Context effects also occurred on no-target trials as evidenced by an enhanced early-evoked response when they followed compatible compared to incompatible trials, suggesting that spatial attention was also modulated by recent context. These results support a multi-componential account of spatial and nonspatial attention and they suggest that contextually driven cognitive control mechanisms can operate on specific stimulus features at extremely early stages of processing within stimulus-response conflict tasks.
Consequences, Action, and Intention as Factors in Moral Judgments: An fMRI Investigation
Authors: Schaich Borg Jana , Hynes Catherine , Van Horn John , Grafton Scott , Sinnott-Armstrong Walter
Published: May 2006

The traditional philosophical doctrines of Consequentialism, Doing and Allowing, and Double Effect prescribe that moral judgments and decisions should be based on consequences, action (as opposed to inaction), and intention. This study uses functional magnetic resonance imaging to investigate how these three factors affect brain processes associated with moral judgments. We find the following: (1) Moral scenarios involving only a choice between consequences with different amounts of harm elicit activity in similar areas of the brain as analogous nonmoral scenarios; (2) Compared to analogous nonmoral scenarios, moral scenarios in which action and inaction result in the same amount of harm elicit more activity in areas associated with cognition (such as the dorsolateral prefrontal cortex) and less activity in areas associated with emotion (such as the orbitofrontal cortex and temporal pole); (3) Compared to analogous nonmoral scenarios, conflicts between goals of minimizing harm and of refraining from harmful action elicit more activity in areas associated with emotion (orbitofrontal cortex and temporal pole) and less activity in areas associated with cognition (including the angular gyrus and superior frontal gyrus); (4) Compared to moral scenarios involving only unintentional harm, moral scenarios involving intentional harm elicit more activity in areas associated with emotion (orbitofrontal cortex and temporal pole) and less activity in areas associated with cognition (including the angular gyrus and superior frontal gyrus). These findings suggest that different kinds of moral judgment are preferentially supported by distinguishable brain systems.