Michael S Gazzaniga

Michael S Gazzaniga
University of California, Santa Barbara | UCSB

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247
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Publications (247)
Chapter
After the first callosotomy surgeries were performed, the general consensus among the medical community was that severing the corpus callosum had relatively little, if any, effect on an individual's behavior. Nearly twenty years later, researchers discovered that, under experimental conditions, the two hemispheres could simultaneously maintain very...
Chapter
Years later Dr. Bogen, then a resident of Van Wagenen, made the same point to one of us (MSG).
Book
Michael S Gazzaniga Richard B. Ivry George R. Mangun Neuroscienze cognitive Seconda edizione italiana condotta sulla quarta edizione americana Gli autori Michael S. Gazzaniga ha fondato e dirige il Center for Cognitive Neuroscience presso il Dartmouth College, New Hampshire, ed è professore di Neuroscienze cognitive presso la University of Cali...
Article
Extensive behavioral evidence has revealed that humans automatically develop internal representations that are adapted to the temporal and spatial statistics of the environment. However, the neural systems underlying this statistical learning process are not fully understood. Recently, various neuroimaging methods have been employed to examine this...
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Objective: Psychopathy is a personality disorder with symptoms that include lack of empathy or remorse, antisocial behavior, and excessive self-focus. Previous neuroimaging studies have linked psychopathy to dysfunction in the default mode network (DMN), a brain network that deactivates during externally focused tasks and is more engaged during se...
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A recently published study by the present authors reported evidence that functional changes in the anterior cingulate cortex within a sample of 96 criminal offenders who were engaged in a Go/No-Go impulse control task significantly predicted their rearrest following release from prison. In an extended analysis, we use discrimination and calibration...
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Identification of factors that predict recurrent antisocial behavior is integral to the social sciences, criminal justice procedures, and the effective treatment of high-risk individuals. Here we show that error-related brain activity elicited during performance of an inhibitory task prospectively predicted subsequent rearrest among adult offenders...
Article
Neuroimaging and the discipline of cognitive neuroscience have grown together in lock-step with each pushing the other toward an improved ability to explore and examine brain function and form. However successful neuroimaging and the examination of cognitive processes may seem today, the culture of data sharing in these fields remains underdevelope...
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Fifty years ago Gazzaniga and coworkers published a seminal article that discussed the separate roles of the cerebral hemispheres in humans. Today, the study of interhemispheric communication is facilitated by a battery of novel data analysis techniques drawn from across disciplinary boundaries, including dynamic systems theory and network theory....
Article
Using an autobiographical approach, I review several animal and human split-brain studies that have led me to change my long-term view on how best to understand mind/brain interactions. Overall, the view is consistent with the idea that complex neural systems, like other complex information processing systems, are highly modular. At the same time,...
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In this paper, our goal is to (a) survey some of the legal contexts within which violence risk assessment already plays a prominent role, (b) explore whether developments in neuroscience could potentially be used to improve our ability to predict violence, and (c) discuss whether neuropredictive models of violence create any unique legal or moral p...
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Several studies report a right hemisphere advantage for visuospatial integration and a left hemisphere advantage for inferring conceptual knowledge from patterns of covariation. The present study examined hemispheric asymmetry in the implicit learning of new visual feature combinations. A split-brain patient and normal control participants viewed m...
Article
Although the ultimate aim of neuroscientific enquiry is to gain an understanding of the brain and how its workings relate to the mind, the majority of current efforts are largely focused on small questions using increasingly detailed data. However, it might be possible to successfully address the larger question of mind-brain mechanisms if the cumu...
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Brain scans and other types of neurological evidence are rarely a factor in trials today. Someday, however, they could transform judicial views of personal credibility and responsibility
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If Scientists Can Prove That The Brain Determines The Mind, Lawyers Could Convince Juries That Defendants May Not Be Responsible For Their Crimes
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An extraterrestrial lands on Earth and, naturally enough, wants to know what makes humans tick. ET wonders whether humans might know themselves, so he (it?) visits laboratories – the very best neuroscience laboratories. There ET sees people sticking electrodes into single neurons within multibillion-neuron brains in the hope that they can decode ho...
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Recent neuroimaging studies suggest lateralized cerebral mechanisms in the right temporal parietal junction are involved in complex social and moral reasoning, such as ascribing beliefs to others. Based on this evidence, we tested 3 anterior-resected and 3 complete callosotomy patients along with 22 normal subjects on a reasoning task that required...
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Split-brain patients, in whom the cortical commissures, principally the corpus callosum, have been cut, provide a unique window into functional specialization of each cerebral hemisphere. Early testing of these patients, using various methods for lateralizing stimulus input and responses, confirmed hemispheric specializations suspected from previou...
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Human morality provides the foundation for many of the pillars of society, informing political legislation and guiding legal decisions while also governing everyday social interactions. In the past decade, researchers in the field of cognitive neuroscience have made tremendous progress in the effort to understand the neural basis of human morality....
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1Defining Consciousness2Foundations of Consciousness3Extended Consciousness: Integration across Content Modules4Modules of Extended Consciousness5Unity of Consciousness6SummaryKeywords:consciousness;interpreter;split-brain;global disorders of consciousness;neural modules;hemispheric specialization;global workspace;visual awareness;attention;emotion...
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Maintaining an accurate mental representation of the current environment is crucial to detecting change in that environment and ensuring behavioral coherence. Past experience with interactions between objects, such as collisions, has been shown to influence the perception of object interactions. To assess whether mental representations of object in...
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The corpus callosum is the largest white matter pathway in the human brain. The most posterior portion, known as the splenium, is critical for interhemispheric communication between visual areas. The current study employed diffusion tensor imaging to delineate the complete cortical projection topography of the human splenium. Homotopic and heteroto...
Article
By definition, the species Homo sapiens is unique. Over a time course of approximately seven million years, humans have evolved into quite a different animal from what was the last common ancestor we share with our closest surviving relative, the chimpanzee. Trying to figure out how we came to be what we are, and identifying what aspects, both phys...
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Understanding the actions performed by other people is a key aspect of social interaction, including in clinical settings where patients are learning from therapists and caregivers. While lesions of the left cerebral hemisphere induce praxic disorders, the hemispheric specialisation of intention understanding remains unclear. Do patients with a rig...
Article
Some of the implications for law of recent discoveries in neuroscience are considered in a new program established by the MacArthur Foundation. A group of neuroscientists, lawyers, philosophers, and jurists are examining issues in criminal law and, in particular, problems in responsibility and prediction and problems in legal decision making.
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The brain relies on interhemispheric communication for coherent integration of cognition and behavior. Surgical disconnection of the two cerebral hemispheres has granted numerous insights into the functional organization of the corpus callosum (CC) and its relationship to hemispheric specialization. Today, technologies exist that allow us to examin...
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Can neurological evidence help courts assess criminal responsibility? To answer this question, we must first specify legal criteria for criminal responsibility and then ask how neurological findings can be used to determine whether particular defendants meet those criteria. Cognitive neuroscience may speak to at least two familiar conditions of cri...
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Diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) were combined to examine the relationship between callosal organization and cortical activity across hemispheres. Healthy young adults performed an incidental verbal encoding task (semantic judgments on words) while undergoing fMRI. Consistent with previous studies, the...
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Decades of research have suggested that consciousness involves processing by distributed networks of functionally specific brain areas that may be selectively damaged. Conscious experience, however, seems unitary and coherent, and this impression may be preserved in patients in whom some of the processes normally available to awareness have been da...
Chapter
This chapter contains section titled: Characterizing Consciousness in the Split- Brain Patient Examining the Corpus Callosum's Contribution to Unified Subjective Experience Explaining Unified Conscious Experience in the Split Brain Toward an Understanding of the Neural Bases of Consciousness Conclusions Characterizing Consciousness in the Split- Br...
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For several decades, cognitive research on personality and individual differences has focused on psychological traits other than general intelligence. Here we present data on empathizing and systemizing cognitive traits in science and humanities students. In view of existing data on autistic traits in scientists, we hypothesized that the science st...
Article
The purpose of the study was to investigate simple calculation in the two cerebral hemispheres of a split-brain patient. In a series of four experiments, the left hemisphere was superior to the right in simple calculation, confirming the previously reported left hemisphere specialization for calculation. In two different recognition paradigms, righ...
Book
Book Description: Written by leading researchers in the field, Cognitive Neuroscience: The Biology of the Mind shows how the complex processes of the mind--language, memory, attention, feelings--are enabled by the underlying biology of the brain. Relying on patient studies and case histories rather than lab experiments on animals, the authors explo...
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People who are partially blind due to brain damage or surgery that has compromised their visual system can occasionally respond to stimuli placed within their region of clinically defined blindness. This phenomenon has come to be called “blindsight” because the patients show “sight” where they are clinically “blind.” Blindsight, by its very nature,...
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We recoil at the idea of people taking drugs to enhance their intelligence. But why?
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The own-race bias (ORB) in facial recognition is characterised by increased accuracy in recognition of individuals from one's own racial group, relative to individuals from other racial groups. Here we report data from a split-brain patient indicating that the ORB may be tied to functions lateralised in the right cerebral hemisphere. Patient JW (a...
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An understanding of relations between causes and effects is essential for making sense of the dynamic physical world. It has been argued that this understanding of causality depends on both perceptual and inferential components. To investigate whether causal perception and causal inference rely on common or on distinct processes, the authors tested...
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Is there a hemispheric asymmetry in the implicit learning of new visual features? New visual features represent spatial structures based on perceptual grouping (a right hemisphere, RH, task), but they also lead to conceptual knowledge of the feature (a LH task). We contrasted the performance of 16 normal subjects with that of a split-brain patient....
Article
Forty-five years ago, Roger Sperry, Joseph Bogen and I embarked on what are now known as the modern split-brain studies. These experiments opened up new frontiers in brain research and gave rise to much of what we know about hemispheric specialization and integration. The latest developments in split-brain research build on the groundwork laid by t...
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Functional magnetic resonance imaging (fMRI) was used to examine the neural correlates of perceptual causality. Participants were imaged while viewing alternating blocks of causal events in which a ball collides with, and causes movement of another ball, versus non-causal events in which a spatial or a temporal gap precedes the movement of a second...
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Neuroscience is improving the understanding of what the brain do when people think and make choices. One important context in neuroscience is biomedical cloning for stem cell research. Neuroscience shows that the fertilized egg does not begin the process that eventually generate a nervous system until day 14. Personal responsibility arises out of i...
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Visual spatial attention has long been associated with facilitatory effects on visual perception. Here, we report that spatial attention can also modulate implicit visuomotor processing in dorsal regions of human cortex. Participants underwent fMRI scanning while performing a voluntary attentional orienting task that varied the category of a task-i...
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In the present study, we combined 2 types of magnetic resonance technology to explore individual differences on a task that required the recognition of objects presented from unusual viewpoints. This task was chosen based on previous work that has established the necessity of information transfer from the right parietal cortex to the left inferior...
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The overwhelming majority of evidence indicates that the left cerebral hemisphere of right-handed humans is dominant both for manual control and the representation of acquired skills, including tool use. It is, however, unclear whether these functions involve common or dissociable mechanisms. Here we demonstrate that the disconnected left hemispher...
Article
Neuroimaging data have implicated regions of the ventral temporal cortex (e.g., fusiform gyrus) as functionally important in face recognition. Recent evidence, however, suggests that these regions are not face-specific, but rather reflect subordinate-level categorical processing underpinned by perceptual expertise. Moreover, when people possess exp...
Article
Neuroimaging and lesion studies have provided insights into the neural mechanisms underlying numerical processing, yet the roles of the right and left hemispheres have not been systematically investigated within a single study. To address this issue, we investigated subitizing and magnitude comparison abilities in a split-brain patient. The first e...
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If the biological basis of language is to provide insight for linguistic theory, description of the aspects of language that play a role in the determination of language lateralization is essential. This article will summarize what is known about the distribution of language across the hemispheres using information from the Wada procedure and compa...
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In a simple manual reaction time task, reaction times are longer if the responding hand and visual field of the stimulus are contralateral than when the hand and field are ipsilateral. This small crossed vs. uncrossed difference (CUD) has often been attributed to the interhemispheric transmission time incurred when the hemisphere receiving the sens...
Article
A variety of visual mental imagery tasks have been shown to activate regions of visual cortex that subserve the perception of visual events. Here fMRI was used to examine whether imagery‐related visuocortical activity is modulated if imagery content is held constant but there is a change in the memory retrieval strategy used to invoke imagery. Part...
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The current experiment examined the neural substrates of response selection, comparing conditions that required participants to make criterion-free selections from sets of same-sex faces (i.e., inconsequential decision) to choosing a dinner date from opposite-sex faces (i.e., consequential decision). In each of these tasks, either a single face (i....
Article
Converging evidence suggests that temporal representations of brief durations are derived subcortically. We tested split-brain patient JW in order to investigate whether these representations project bilaterally or unilaterally to cortex. Using visual stimuli to signal time intervals, JWwas asked to compare the duration of a pair of standard stimul...
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After more than a decade of collecting large neuroimaging datasets, neuroscientists are now working to archive these studies in publicly accessible databases. In particular, the fMRI Data Center (fMRIDC), a high-performance computing center managed by computer and brain scientists, seeks to catalogue and openly disseminate the data from published f...
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The involvement of specific brain areas in carrying out specific tasks has been increasingly well documented over the past decade. Many of these processes are highly automatic and take place outside of conscious awareness. Conscious experience, however, seems unitary and must involve integration between distributed processes. This article presents...
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Divided visual field studies of neurologically normal adults indicate that the left hemisphere is superior to the right in making temporal judgments. Some neuroimaging and neuropsychological studies, however, have suggested a role for the right hemisphere in temporal processing. We tested the divided hemispheres of a split-brain patient in two task...
Article
A truly remarkable aspect of human existence is the unitary sense of self that exists across time and place. Understanding the nature of self—what it is and what it does—has challenged scholars since antiquity. How can empirical research measure what it is to have a sense of self? We propose that the sense of self may emerge from the functions of a...
Article
Identification of visually presented words is facilitated by implicit memory, or visual priming, for past visual experiences with those words. There is disagreement over the neuro-anatomical substrates of this form of implicit memory. Several studies have suggested that this form of priming relies on a visual word-form system localized in the right...
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Recent studies that identify distinct neural correlates of perceptual awareness offer a promising step towards improved understanding of the neurological underpinnings of conscious experience. Such studies indicate that perceptual awareness is modular in nature, with neural correlates of awareness consisting of the specialized structures involved i...
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Visually guided grasping movements require a rapid transformation of visual representations into object-specific motor programs. Here we report that graspable objects may facilitate these visuomotor transformations by automatically grabbing visual spatial attention. Human subjects viewed two task-irrelevant objects--one was a 'tool', the other a 'n...
Article
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Article
Converging evidence suggests that temporal representations of brief durations are derived subcortically. We tested split-brain patient JW in order to investigate whether these representations project bilaterally or unilaterally to cortex. Using visual stimuli to signal time intervals, JW was asked to compare the duration of a pair of standard stimu...
Article
It is generally held that motor imagery is the internal simulation of movements involving one's own body in the absence of overt execution. Consistent with this hypothesis, results from numerous functional neuroimaging studies indicate that motor imagery activates a large variety of motor-related brain regions. However, it is unclear precisely whic...
Article
Efforts for the sharing of neuroscientific data depend on the ability of researchers to intelligently organize and manage their study information prior to it being shared. This involves the need for software tools for investigators to use in visualization, navigation, and exploration of their study data in an easy and accessible manner in which the...
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Accurate performance of reaching movements depends on adaptable neural circuitry that learns to predict forces and compensate for limb dynamics. In earlier experiments, we quantified generalization from training at one arm position to another position. The generalization patterns suggested that neural elements learning to predict forces coded a lim...
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The localization of brain functions using neuroimaging techniques is commonly dependent on statistical analyses of groups of subjects in order to identify sites of activation, particularly in studies of episodic memory. Exclusive reliance on group analysis may be to the detriment of understanding the true underlying cognitive nature of brain activa...
Article
D uring the deliberations of the U.S. President's Council on Bioethics, we raised many questions about the comparative usefulness of embryonic and adult human stem cells for treating a host of fatal and nonfatal but debilitating diseases. We never received clear answers, so the prospect of stem cell
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A split-brain patient (epileptic individual whose corpus callosum had been severed to minimize the spread of seizure activity) was asked to recognize morphed facial stimuli--presented separately to each hemisphere--as either himself or a familiar other. Both hemispheres were capable of face recognition, but the left hemisphere showed a recognition...
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Full-text available
Previous neuroimaging studies have claimed a left hemisphere specialization for episodic "encoding" and a right hemisphere specialization for episodic "retrieval." Yet studies of split-brain patients indicate relatively minor memory impairment after disconnection of the two hemispheres. This suggests that both hemispheres are capable of encoding an...
Article
Enormous progress has been made over the past decade in the development of neuroimaging technology to study in vivo brain function. But as was once the case in genomics, much of the raw functional imaging data that are collected and described in the literature have not been made available to other researchers. The fMRI Data Center aims to archive r...
Article
When a line is flashed instantaneously between two markers it can appear to propagate from one marker to the other. This illusion is known as the line motion effect. We investigated this effect in the two hemispheres of a callosotomy ("split-brain") patient. We found that both hemispheres perceived the line motion effect, and that flashing one of t...
Conference Paper
When a line is flashed instantaneously between two markers it can appear to propagate from one marker to the other. This illusion is known as the line motion effect. We investigated this effect in the two hemispheres of a callosotomy ("split-brain") patient. We found that both hemispheres perceived the line motion effect, and that flashing one of t...
Article
While it is commonly noted that the right cerebral hemisphere is specialized for visuospatial processing, the scope and nature of this specialization remain somewhat ill defined. Our previous research with callosotomy ('split-brain') patients has suggested that the asymmetry may be limited to conditions that have an explicit spatial component. To i...