bluuebunny/crossref_metadata_2025_split huggingface dataset:
On Neural Codes and Perception
Authors: Newsome William T. 
Published: February 2008

Abstract
Bill Newsome is a professor in the Department of Neurobiology at the Stanford University School of Medicine. He received his B.S. in physics from Stetson University in 1974 and his Ph.D. in biology from Caltech in 1980. Following postdoctoral work at MH, he served on the faculty at SUNY Stony Brook before joining the Stanford faculty in 1988. His research has focused on the neural mechanisms underlying visual perception and visually guided behavior. Bill was a corecipient of the Rank Prize in optoelectronics in 1992, and received the Minerva Foundation's Golden Brain Award in the same year. This fall he received the Spencer Award, granted yearly by the College of Physicians and Surgeons at Columbia University for highly original contributions to research in neurobiology. In addition, he won the Kaiser Award for excellence in preclinical teaching granted annually by the Stanford School of Medicine.
Is There a Social Module? Language, Face Processing, and Theory of Mind in Individuals with Williams Syndrome
Authors: Karmiloff-Smith Annette , Klima Edward , Bellugi Ursula , Grant Julia , Baron-Cohen Simon 
Published: February 2008

Abstract
Many species can respond to the behavior of their conspecifics. Human children, and perhaps some nonhuman primates, also have the capacity to respond to the mental states of their conspecifics, i.e., they have a “theory of mind.” On the basis of previous research on the theory-of-mind impairment in people with autism, together with animal models of intentionality, Brothers and Ring (1992) postulated a broad cognitive module whose function is to build representations of other individuals. We evaluate the details of this hypothesis through a series of experiments on language, face processing, and theory of mind carried out with subjects with Williams syndrome, a rare genetic neurodevelopmental disorder resulting in an uneven lin-guisticocognitive profile. The results are discussed in terms of how the comparison of different phenotypes (e.g., Williams syndrome, Down syndrome, autism, and hydrocephaly with associated myelomeningocele) can contribute both to understanding the neuropsychology of social cognition and to current thinking about the purported modularity of the brain.
Word and Nonword Repetition Within- and Across-Modality: An Event-Related Potential Study
Authors: Rugg Michael D. , Doyle Michael C. , Wells Tony 
Published: February 2008

Abstract
The effects on event-related potentials (ERPs) of within- and across-modality repetition of words and nonwords were investigated. In Experiment 1, subjects detected occasional animal names embedded in a series of words. AU items were equally likely to be presented auditorily or visually. Some words were repetitions, either within- or across-modality, of words presented six items previously. Visual-visual repetition evoked a sustained positive shift, which onset around 250 msec and comprised two topographically and temporally distinct components. Auditory-visual repetition modulated only the later of these two components. For auditory EMS, within- and across-modality repetition evoked effects with similar onset latencies. The within-modality effect was initially the larger, but only at posterior sites. In Experiment 2, critical items were auditory and visual nonwords, and target items were auditory words and visual pseudohomophones. Visual-visual nonword repetition effects onset around 450 msec, and demonstrated a more anterior scalp distribution than those evoked by auditory-visual repetition. Visual-auditory repetition evoked only a small, late-onsetting effect, whereas auditory-auditory repetition evoked an effect that, at parietal sites only, was almost equivalent to that from the analogous condition of Experiment 1. These findings indicate that, as indexed by ERF's, repetition effects both within- and across-modality are influenced by lexical status. Possible parallels with the effects of word and nonword repetition on behavioral variables are discussed.
Spatial versus Object Working Memory: PET Investigations
Authors: Smith Edward E. , Jonides John , Koeppe Robert A. , Awh Edward , Schumacher Eric H. , Minoshima Satoshi 
Published: February 2008

Abstract
We used positron emission tomography (PET) to answer the following question: Is working memory a unitary storage system, or does it instead include different storage buffers for different kinds of information? In Experiment 1, PET measures were taken while subjects engaged in either a spatial-memory task (retain the position of three dots for 3 sec) or an object-memory task (retain the identity of two objects for 3 sec). The results manifested a striking double dissociation, as the spatial task activated only right-hemisphere regions, whereas the object task activated primarily left-hemisphere regions. The spatial (right-hemisphere) regions included occipital, parietal, and prefrontal areas, while the object (left-hemisphere) regions included inferotemporal and parietal areas. Experiment 2 was similar to Experiment 1 except that the stimuli and trial events were identical for the spatial and object tasks; whether spatial or object memory was required was manipulated by instructions. The PET results once more showed a double dissociation, as the spatial task activated primarily right-hemisphere regions (again including occipital, parietal and prefrontal areas), whereas the object task activated only left-hemisphere regions (again including inferotemporal and parietal areas). Experiment 3 was a strictly behavioral study, which produced another double dissociation. It used the same tasks as Experiment 2, and showed that a variation in spatial similarity affected performance in the spatial but not the object task, whereas a variation in shape similarity affected performance in the object but not the spatial task. Taken together, the results of the three experiments clearly imply that different working-memory buffers are used for storing spatial and object information.
PET Studies of Auditory and Phonological Processing: Effects of Stimulus Characteristics and Task Demands
Authors: Fiez J. A. , Raichle M. E. , Miezin F. M. , Petersen S. E. , Tallal P. , Katz W. F. 
Published: February 2008

AbstractPositron emission tomography (PET) was used to investigate the functional anatomy of auditory and phonological processing. Stimulus sets were designed to determine areas of the brain significantly activated during speech and nonspeech acoustic processing for stimuli with or without rapidly changing acoustic cues. Performance of auditory target detection tasks using these stimulus sets produced increased activation in superior temporal, frontal opercular, and medial frontal (SMA) cortices, relative to a visual fixation control task. While the medial frontal and superior temporal changes are best explained by motor and sensory components of the task, respectively, the frontal opercular changes were dependent upon the task performed upon the auditory input (mere presentation of the stimuli did not result in significant activation). On the left, the frontal opercular increases were larger when subjects performed an auditory detection task upon stimuli that incorporated rapid temporal changes (words, syllables, and tone sequences) than steady-state vowels. A converging study involving performance of orthographic (ascending letter) and phonological (long vowel sound) word discrimination tasks supports anatomical and behavioral evidence suggesting the left frontal opercular region is important for certain types of auditory/temporal analysis, as well as high-level articulatory coding.In addition to the activation increases associated with performance of auditory target detection tasks, decreases in activation were observed bilaterally along the intraparietal sulcus and superior parietal cortex, in the Rolandic sulcus, and the posterior cingulate; these decreases may reflect an attentional shift away from areas involved in the fixation task during the performance of a difficult auditory task.These results demonstrate that focusing more closely on basic neural processing differences (such as temporal integration rates) may lead to a better understanding of the specific neural processes that underlie complex phonological tasks.
A Neural Network Simulation of Hallucinated “Voices” and Associated Speech Perception Impairments in Schizophrenic Patients
Authors: Hoffman Ralph E. , Rapaport Jill , Ameli Rezvan , McGlashan Thomas H. , Harcherik Diane , Servan-Schreiber David 
Published: February 2008

Abstract
The mechanism of hallucinated speech, a symptom commonly reported by schizophrenic patients, is unknown. The hypothesis that these hallucinations arise from pathologically altered working memory underlying speech perception was explored. A neural network computer simulation of contextually guided sequential word detection based on Elman (1990a,b) was studied. Pruning anatomic connections or reducing neuronal activation in working memory caused word “percepts” to emerge spontaneously (i.e., in the absence of external “speech inputs”), thereby providing a model of hallucinated speech. These simulations also demonstrated distinct patterns of word detection impairments when inputs were accompanied by varying levels of noise. In a parallel human study, the ability to shadow noisecontaminated, connected speech was assessed. Schizophrenic patients reporting hallucinated speech demonstrated a pattern of speech perception impairments similar to a simulated neural network with reduced anatomic connectivity and enhanced neuronal activation. Schizophrenic patients not reporting this symptom did not demonstrate these speech perception impairments. Neural network simulations and human empirical data, when considered together, suggested that the primary cause of hallucinated “voices” in schizophrenia is reduced neuroanatomic connectivity in verbal working memory.
Computerized Mappings of the Cerebral Cortex: A Multiresolution Flattening Method and a Surface-Based Coordinate System
Authors: Drury Heather A. , Van Essen David C. , Anderson Charles H. , Lee Chris W. , Coogan Thomas A. , Lewis James W. 
Published: February 2008

Abstract
We present a new method for generating two-dimensionnl maps of the cerebral cortex. Our computerized, two-stage flattening method takes as its input any well-defined representation of a surface within the three-dimensional cortex. The first stage rapidly converts this surface to a topologically correct two-dimensional map. without regard for the amount of distortion introduced. The second stage reduces distortions using a multiresolution strategy that makes gross shape changes on a coarsely sampled map and further shape refinements on progressively finer resolution maps. We demonstrate the utility of this approach by creating flat maps of the entire cerebral cortex in the macaque monkey and by displaying various types of experimental data on such maps. We also introduce a surface-based coordinate system that has advantages over conventional stereotaxic coordinates and is relevant to studies of cortical organization in humans as well as non-human primates. Together, these methods provide an improved basis for quantitative studies of individual variability in cortical organization.
Monkey and Human Face Perception: Inversion Effects for Human Faces But Not for Monkey Faces or Scenes
Authors: Wright Anthony A. , Roberts William A. 
Published: February 2008

Abstract
Three rhesus monkeys and two groups of 10 human subjects judged upright or inverted pictures as same or different. The pictures were black and white pairs of human faces, monkey faces, or scenes. The monkeys were trained with sets of 50 pictures and were tested with other sets of 36 pictures from each category. The groups of 10 human subjects were tested with the same pictures used to test monkeys. Both monkeys and humans showed large performance decrements to inverted human faces relative to upright human faces but neither species showed inversion effects for monkey faces or scenes. A second test with both monkeys and humans showed the same pattern of results with a different set of human-face pictures that varied more in sex (female as well as male), facial hair, eyeglasses, haircut, view angle, and background than those of the first test. The results indicate similar face-processing mechanisms in monkeys and humans despite experiential and evolutionary differences.
Effects of LTP on Response Selectivity of Simulated Cortical Neurons
Authors: Kilborn Karl , Lynch Gary , Granger Richard 
Published: February 2008

Abstract
We report here on specific ways in which synaptic long-term potentiation (LTP) affects the response selectivity of primary sensory cortical cells. LTP increases synaptic efficacy by incremental “steps,” up to a “ceiling” at which additional bursts of afferent stimulation cause no further potentiation. Endogenous and exogenous agents have been shown to modulate these two paramenters of LTP, raising the question of the functional implications associated with the sizes of steps and ceiling. We provide an analytical treatment of the effects of these two physiological LTP parameters on the behavior of simulated olfactory (piriform) cortex target cells in response to a range of inputs. A target cell's receptive field, i.e., the set of input patterns to which the cell responds, is broadened with potentiation of the cell's synapses, and is broadened more when the LTP step size is smaller, and when the LTP ceiling is higher. Moreover, the effects of step size and ceiling interact, and their joint relationship to receptive field breadth is nonlinear. Values of step size and ceiling are identified that balance the tradeoff between learning rate and receptive field breadth for particular sensory recognition tasks, and these model values are compared to corresponding known and inferred physiological values.
The Magnitude of the Fixation Offset Effect with Endogenously and Exogenously Controlled Saccades
Authors: Forbes Kelly , Klein Raymond M. 
Published: February 2008

Abstract
Two experiments examined saccadic reaction time (RT) in response to visual targets as a function of fixation offset condition (no offset; target simultaneous with offset and 200-msec offset-target SOA) in prosaccade and antisaccade tasks. The second experiment also included a condition in which saccades were made in response to verbal commands presented auditorally. To ensure that observers were equally prepared in each condition, auditory warning tones preceded target onset on every trial. The RT reduction associated with fixation offset (FOE, or gap effect) was identical with visual targets in the prosaccade task and in response to verbal signals, strongly implicating motor, rather than sensory, mechanisms in the FOE. The FOE in the antisaccade task was significant, but it was also significantly smaller than in the other tasks. We speculate that the reduced FOE in the antisaccade task may be due to the requirement to inhibit the superior colliculus when the target directed saccadic programs are, by instruction, erroneous.
On Knowing the Auxiliary of a Verb That Cannot Be Named: Evidence for the Independence of Grammatical and Phonological Aspects of Lexical Knowledge
Authors: Miozzo Michele , Caramazza Alfonso 
Published: February 2008

Abstract
We report the case of an Italian anomic subject who was invariably able to provide the auxiliary of verbs he failed to produce in oral naming tasks. This pattern of performance contrasts with that of another Italian-speaking patient documented by Miceli and Caramazza (1988) who showed a selective impairment in accessing syntactic features of words, but not their phonological forms. This double dissociation suggests that syntactic and phonological information in the lexicon are accessed independently and represented in distinct neural structures.
Hemispheric Organization of Visual Memories
Authors: Gratton Gabriele , Corballis Paul M. , Jain Shamini 
Published: February 2008

Abstract
This study investigates the hemispheric organization of visual memories. In five experiments, we examine the processes associated with the recognition of line patterns that are flashed laterally during a study phase. The first three experiments demonstrate a recognition advantage for patterns presented at test in the same (rather than in the opposite) hemifield in which they were presented during a previous study phase. This difference was obtained even when stimuli were presented in different locations within the same hemifield. Experiment shows that patterns presented centrally during the recognition phase elicit ERPs that are systematically more negative over the hemisphere contralateral to the side at which they were presented during the study phase. In Experiment 5, however, we found that subjects were unable to indicate the side of initial presentation of the patterns. The results suggest that the memory traces left by laterally presented stimuli are more easily accessible in the contralateral hemisphere, which suggests a contralateral organization of visual memories.
Residual Vision in Multiple Retinal Locations within a Scotoma: Implications for Blindsight
Authors: Kentridge R. W. , Heywood C. A. , Weiskrantz L. 
Published: February 2008

Abstract
There is an important new proposal that “blindsight”-the ability to detect and identify visual stimuli by forcedchoice guessing and in the absence of conscious awareness when they fall in blind regions of the visual field—is a function of residual “islands” of undamaged visual cortex. This stands in contrast to the widely accepted view that blindsight is exclusively a function of secondary visual pathways. According to the new view, residual vision in blindsight should be patchy. Thus, when apparently wide areas of residual vision in blindsight are found, these may be due to eye-movements that allow stimuli to pass over retinal locations corresponding to islands of sparing. We tested this hypothesis by examining the distribution of residual vision in blindsight when the effects of eye movements on the retinal location of stimuli were minimized. We report a series of experiments that examined twealternate forcedchoice discrimination in the blind field of the subject GY. Using a dual-Purkinje image eye-tracker we applied three methods of minimizing the effects of retinal slippage due to eye-movements on discrimination performance: fixation stability-dependent trials, software image stabilization, and post hoc rejection of trials in which saccadic eye-movements were detected. In the first experiment, GY's discrimination performance was significantly above chance in 8 of 15 locations tested. In the subsequent experiments the subject knew the location of the target in each block of trials, and this resulted in improvements to performance in a further three locations. Increasing the luminance of the stimulus display (while maintaining 95% target contrast), and increasing the temporal discriminability of the forced choice produced performance above chance in all but two of the locations tested. The consistent chance performance observed in two locations in the lower visual field nevertheless implies that GY's blindsight does not extend over the whole of his scotoma. Nevertheless, abolishing, or minimizing, the effects of eye-movements did not result in a loss of detection in all the widely separated regions tested, and we thus conclude that GY's blindsight cannot adequately be explained in terms of islands of spared vision. Islands may account for residual vision in scotomata in some patients, but cannot be a universal account of the phenomenon of blindsight.
Spatial Transformations in the Parietal Cortex Using Basis Functions
Authors: Pouget Alexandre , Sejnowski Terrence J. 
Published: February 2008

Abstract
Sensorimotor transformations are nonlinear mappings of sensory inputs to motor responses. We explore here the possibility that the responses of single neurons in the parietal cortex serve as basis functions for these transformations. Basis function decomposition is a general method for approximating nonlinear functions that is computationally efficient and well suited for adaptive modification. In particular, the responses of single parietal neurons can be approximated by the product of a Gaussian function of retinal location and a sigmoid function of eye position, called a gain field. A large set of such functions forms a basis set that can be used to perform an arbitrary motor response through a direct projection. We compare this hypothesis with other approaches that are commonly used to model population codes, such as computational maps and vectorial representations. Neither of these alternatives can fully account for the responses of parietal neurons, and they are computationally less efficient for nonlinear transformations. Basis functions also have the advantage of not depending on any coordinate system or reference frame. As a consequence, the position of an object can be represented in multiple reference frames simultaneously, a property consistent with the behavior of hemineglect patients with lesions in the parietal cortex.
Are the Same Attentional Mechanisms Used to Detect Visual Search Targets Defined by Color, Orientation, and Motion?
Authors: Girelli Massimo , Luck Steven J. 
Published: February 2008

Abstract
Motion information tends to be segregated from color and form information in the visual system, both perceptually and neuroanatomically, and it is therefore possible that different mechanisms of attention are used to select targets defined by these different feature types during visual search. To test this hypothesis, we recorded the N2pc component of the event-related potential waveform during visual search tasks with color, orientation, and motion targets. The N2pc component has previously been shown to reflect a specific attentional mechanism that is present for color and form targets, and we sought to determine whether this component would also be present for motion targets. The N2pc component was indeed observed for motion targets as well as color and orientation targets, consistent with the use of a common attentional mechanism across feature types. In addition, we found that motion singletons (i.e., individual items that moved in the opposite direction from the other items in the army) elicited an N2pc component even when they were task-irrelevant, indicating that motion discontinuities may produce an automatic orienting of attention.
A Neural Dissociation within Language: Evidence that the Mental Dictionary Is Part of Declarative Memory, and that Grammatical Rules Are Processed by the Procedural System
Authors: Ullman Michael T. , Corkin Suzanne , Coppola Marie , Hickok Gregory , Growdon John H. , Koroshetz Walter J. , Pinker Steven 
Published: February 2008

Abstract
Language comprises a lexicon for storing words and a grammar for generating rule-governed forms. Evidence is presented that the lexicon is part of a temporal-parietalhnedial-temporal “declarative memory” system and that granlmatical rules are processed by a frontamasal-ganglia “procedural” system. Patients produced past tenses of regular and novel verbs (looked and plagged), which require an -ed-suffixation rule, and irregular verbs (dug), which are retrieved from memory. Word-finding difficulties in posterior aphasia, and the general declarative memory impairment in Alzheimer's disease, led to more errors with irregular than regular and novel verbs. Grammatical difficulties in anterior aphasia, and the general impairment of procedures in Parkinson's disease, led to the opposite pattern. In contrast to the Parkinson's patients, who showed sup pressed motor activity and rule use, Huntington's disease patients showed excess motor activity and rule use, underscoring a role for the basal ganglia in grammatical processing.