Functional Tests of the Corpus Callosum in Schizophrenia

1981 ◽  
Vol 139 (6) ◽  
pp. 553-557 ◽  
Author(s):  
Gareth H. Jones ◽  
Julian J. Miller
Keyword(s):  
Corpus Callosum ◽  
Chronic Schizophrenia ◽  
Evoked Response ◽  
Cerebral Hemispheres ◽  
Conduction Time ◽  
Functional Tests ◽  
Split Brain ◽  
Sensory Pathways ◽  
Somatosensory Evoked Response ◽  
Brain Condition

SummaryThe corpus callosum, a cerebral commissure of 200,000,000 fibres, is thickened in chronic schizophrenia and several neuropsychological and neurophysiological techniques have suggested poor links between the two cerebral hemispheres. The interhemispheric conduction time across the corpus callosum, measured in 12 schizophrenics, using the ipsilateral/contralateral latency differences of the early somatosensory evoked response, was found to be effectively zero. It is suggested that schizophrenia is a split-brain condition akin to agenesis of the corpus callosum, unrecognized through the use of compensatory ipsilateral sensory pathways.

Self-Consciousness and "Split" Brains

2018 ◽  
Author(s):  
Elizabeth Schechter
Keyword(s):  
United States ◽  
Twentieth Century ◽  
Corpus Callosum ◽  
Human Brain ◽  
The United States ◽  
The Other ◽  
Cerebral Hemispheres ◽  
Experimental Conditions ◽  
Fiber Tract ◽  
Split Brain

The largest fiber tract in the human brain is the corpus callosum, which connects the two cerebral hemispheres. A number of surgeries severing this structure were performed on adults in the United States in the second half of the twentieth century. After they are surgically separated from each other in this way, a “split-brain” subject’s hemispheres begin to operate unusually independently of each other in the realms of perception, cognition, and the control of action—almost as if each had a mind of its own. But can a mere hemisphere really see? Speak? Feel? Know what it has done? The split-brain cases raise questions of psychological identity: How many subjects of experience are there within a split-brain subject? How many persons? How many minds? Under experimental conditions, split-brain subjects often act as though they were animated by two distinct conscious beings, evoking the duality intuition. On the other hand, a split-brain subject seems like one of us—not like two of us sharing one body. Split-brain subjects thus also evoke the unity intuition.This book is devoted to reconciling these two apparently opposing intuitions. The key to doing so are facts about the way self-consciousness operates in split-brain subjects. A split-brain subject is composed of two conscious psychological beings that fail to recognize each other’s existence and indeed cannot distinguish themselves from each other. Instead, each must first-personally identify with the split-brain subject as a whole, and in so doing, the two make themselves into one person.

Brain Disconnection and Schizophrenia

1973 ◽  
Vol 123 (577) ◽  
pp. 661-662 ◽  
Author(s):  
J. G. Beaumont ◽  
S. J. Dimond
Keyword(s):  
Corpus Callosum ◽  
The Body ◽  
The Other ◽  
Cerebral Hemispheres ◽  
Split Brain ◽  
Cross Match ◽  
As If

The concept of brain disconnection derives from work in which the two cerebral hemispheres are surgically separated by division of the corpus callosum. The patient behaves as if his two half-brains function to some degree independently. The syndrome of brain disconnection is exemplified by such split-brain cases (Geschwind, 1965). Neither hemisphere shows an awareness of the functions of the other, and there is a marked failure to cross-match stimuli across the midline of the body. The integrity of the corpus callosum is essential to normal integration between the hemispheres.

Independent Attentional Scanning in the Separated Hemispheres of Split-Brain Patients

1994 ◽  
Vol 6 (1) ◽  
pp. 84-91 ◽  
Author(s):  
Steven J. Luck ◽  
Steven A. Hillyard ◽  
George R. Mangun ◽  
Michael S. Gazzaniga
Keyword(s):  
Visual Search ◽  
Corpus Callosum ◽  
Search Task ◽  
Visual Search Task ◽  
Target Item ◽  
Attentional Focus ◽  
Focus Of Attention ◽  
Cerebral Hemispheres ◽  
Search Rate ◽  
Split Brain

Previous studies of visuospatial attention indicated that the isolated cerebral hemispheres of split-brain patients maintain an integrated, unitary focus of attention, presumably due to subcortical attentional mechanisms. The present study examined whether a unitary attentional focus would also be observed during a visual search task in which subjects scanned stimulus arrays for a target item. In a group of four commis-surotomy patients, the search rate for bilateral stimulus arrays was found to be approximately twice as fast as the search rate for unilateral arrays, indicating that the separated hemispheres were able to scan their respective hemifields independently. In contrast, the search rates for unilateral and bilateral arrays were approximately equal in a group of six normal control subjects, suggesting that the intact corpus callosum in these subjects is responsible for maintaining a unitary attentional focus during visual search.

scholarly journals Characteristics of the corpus callosum in chronic schizophrenia treated with clozapine or risperidone and those never-treated

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Bo Tao ◽  
Yuan Xiao ◽  
Hengyi Cao ◽  
Wenjing Zhang ◽  
Chengmin Yang ◽  
...  
Keyword(s):  
White Matter ◽  
Corpus Callosum ◽  
Clinical Symptoms ◽  
Diffusion Tensor ◽  
Structural Characteristics ◽  
Chronic Schizophrenia ◽  
Cross Sectional Study ◽  
Antipsychotic Treatment ◽  
Cross Sectional

Abstract Background The corpus callosum (CC) deficits have been well documented in chronic schizophrenia. However, the long-term impacts of antipsychotic monotherapies on callosal anatomy remain unclear. This cross-sectional study sought to explore micro- and macro-structural characteristics of the CC in never-treated patients and those with long-term mono-antipsychotic treatment. Methods The study included 23 clozapine-treated schizophrenia patients (CT-SCZ), 19 risperidone-treated schizophrenia patients (RT-SCZ), 23 never-treated schizophrenia patients (NT-SCZ), and 35 healthy controls (HCs). High resolution structural images and diffusion tensor imaging (DTI) data for each participant were obtained via a 3.0 T MR scanner. FreeSurfer was used to examine the volumes and fractional anisotropy (FA) values of the CC for each participant. Results There were significant deficits in the total and sub-regional CC volume and white matter integrity in NT-SCZ in comparison with healthy subjects. Compared with NT-SCZ, both CT-SCZ and RT-SCZ showed significantly increased FA values in the anterior CC region, while only RT-SCZ showed significantly increased volume in the mid-anterior CC region. Moreover, the volume of the mid-anterior CC region was significantly smaller in CT-SCZ compared to HCs. No correlations of clinical symptoms with callosal metrics were observed in schizophrenia patients. Conclusions Our findings provide insight into micro- and macro-structural characteristics of the CC in chronic schizophrenia patients with or without antipsychotics. These results suggest that the pathology itself is responsible for cerebral abnormalities in schizophrenia and that chronic exposure to antipsychotics may have an impact on white matter structure of schizophrenia patients, especially in those with risperidone treatment.

Analysis of 3D Corpus Callosum Images in the Brains of Autistic Individuals

2016 ◽  
pp. 159-184
Author(s):  
Ahmed Elnakib ◽  
Manuel F. Casanova ◽  
Ahmed Soliman ◽  
Georgy Gimel'farb ◽  
Ayman El-Baz
Keyword(s):  
Autism Spectrum Disorder ◽  
Corpus Callosum ◽  
Human Brain ◽  
Shape Analysis ◽  
Neurodevelopmental Disorder ◽  
Autism Spectrum ◽  
Cerebral Hemispheres ◽  
Higher Cognitive Functions ◽  
The Right ◽  
Abnormal Anatomy

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that is characterized by abnormalities in behavior and higher cognitive functions. The corpus callosum (CC) is the largest fiber bundle that connects the left and the right cerebral hemispheres of the human brain. Several studies have revealed an abnormal anatomy of the CC in the brains of autistic individuals that associates this neurodevelopmental condition with impaired communication between the hemispheres. In this chapter, we develop a framework to analyze the CC of autistic individuals in order to provide a diagnostic tool for autism. The key advantage of this approach is the development of a cylindrical mapping that offers simplified coordinates for comparing the brains of autistic individuals and neurotypicals. Experimental results showed significant differences (at the 95% confidence level) between 17 normal and 17 autistic subjects in four anatomical divisions, i.e. splenium, rostrum, genu, and body of their CCs. Moreover, the initial centerline-based shape analysis of the CC documented a promising supplement to the current techniques for diagnosing autism.

Interhemispheric Transmission of Visuomotor Information in Humans: fMRI Evidence

2002 ◽  
Vol 88 (2) ◽  
pp. 1051-1058 ◽  
Author(s):  
M. Tettamanti ◽  
E. Paulesu ◽  
P. Scifo ◽  
A. Maravita ◽  
F. Fazio ◽  
...  
Keyword(s):  
Corpus Callosum ◽  
Visual Information ◽  
Human Subjects ◽  
Conduction Time ◽  
Clear Cut ◽  
Cortical Areas ◽  
Poffenberger Paradigm ◽  
Interhemispheric Transmission ◽  
Hemispheric Activation ◽  
Normal Human

Normal human subjects underwent functional magnetic resonance imaging (fMRI) while performing a simple visual manual reaction-time (RT) task with lateralized brief stimuli, the so-called Poffenberger's paradigm. This paradigm was employed to measure interhemispheric transmission (IT) time by subtracting mean RT for the uncrossed hemifield-hand conditions, that is, those conditions not requiring an IT, from the crossed hemifield-hand conditions, that is, those conditions requiring an IT to relay visual information from the hemisphere of entry to the hemisphere subserving the response. The obtained difference is widely believed to reflect callosal conduction time, but so far there is no direct physiological evidence in humans. The aim of our experiment was twofold: first, to test the hypothesis that IT of visuomotor information requires the corpus callosum and to identify the cortical areas specifically activated during IT. Second, we sought to discover whether IT occurs mainly at premotor or perceptual stages of information processing. We found significant activations in a number of frontal, parietal, and temporal cortical areas and in the genu of the corpus callosum. These activations were present only in the crossed conditions and therefore were specifically related to IT. No selective activation was present in the uncrossed conditions. The location of the activated callosal and cortical areas suggests that IT occurs mainly, but not exclusively, at premotor level. These results provide clear cut evidence in favor of the hypothesis that the crossed-uncrossed difference in the Poffenberger paradigm depends on IT rather than on a differential hemispheric activation.

Failure to Replicate Evoked Potential Observations Suggesting Corpus Callosum Dysfunction in Schizophrenia

1983 ◽  
Vol 142 (5) ◽  
pp. 471-476 ◽  
Author(s):  
Charles Shagass ◽  
Richard C. Josiassen ◽  
Richard A. Roemer ◽  
John J. Straumanis ◽  
Stephen M. Slepner
Keyword(s):  
Corpus Callosum ◽  
Evoked Potential ◽  
Test Procedure ◽  
Conduction Time ◽  
Contralateral Hemisphere ◽  
Normal Controls

SummarySomatosensory potentials (SEPs) evoked by vibrotactile finger stimulation have been reported to be the same in both hemispheres in schizophrenics, whereas they are asymmetrical in normals, with the contralateral hemisphere leading the ipsilateral (Jones and Miller, 1981). These findings were taken to indicate that the corpus callosum is nonfunctional in schizophrenics. To attempt replication of these results, vibrotactile SEPs of 6 schizophrenics and 6 normal controls were recorded with both bipolar and monopolar derivations. Assymetrical bipolar SEPs were obtained in both schizophrenics and controls; previous observations of schizophrenic-control differences were not replicated. Acceptable evidence of ipsilateral early SEPs was not obtained; the test procedure seems inappropriate for measuring callosal conduction time.

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