ReviewHow does the corpus callosum mediate interhemispheric transfer? A review
Highlights
► Corpus callosum important structure in brain hemisphere communication. ► Two theories regarding callosal function; inhibition and excitation. ► Evidence for both theories within same corpus callosum. ► Use of better techniques to measure connectivity for future research. ► Investigate role of callosal sub regions to gain understanding in function.
Introduction
The corpus callosum is a brain structure in placental mammals that connects the left and right cerebral hemispheres. Containing numerous intra- and interhemispheric myelinated axonal projections it is considered to be the largest white matter structure in the brain. Patients undergoing complete or partial corpus callosotomies and callosal lesion studies have provided more insight into its function over the years. These callosotomies served as a treatment for intractable epilepsy, preventing seizures from spreading over the entire brain. The first callosotomy was performed by van Wagenen and Herren [1], and on first sight did not appear to induce any large cognitive or functional deficits. However, more elaborate behavioural studies have shown symptoms specific to callosotomies, now known as the callosal disconnection syndrome. Complete sectioning of the corpus callosum blocked the transfer of information to the opposing hemisphere, resulting in dissociation between left and right and difficulties in transferring learned information.
The unique cognitive state of callosotomized patients has led to more elaborate research regarding hemispheric transfer and communication between different cortical areas and the functional specialization of the corpus callosum. This review will address and investigate recent literature concerning callosal morphology, function and dysfunction in order to investigate the involvement and function of the corpus callosum in brain hemisphere communication.
Section snippets
Brain commissures
Communication between cortical areas of the brain can occur both intra-, as well as interhemispherically. Intrahemispheric communication occurs by means of axonal projections connecting cortices of the frontal, parietal, occipital and temporal lobes, by means of cortico-cortical and cortico-subcortical pathways. This information is also available for interhemispheric processing [2], [3]. Interhemispheric processing occurs through brain commissures; bundles of nerve fibers that connect the two
Animal disconnection studies
Some early studies concerning callosal function were performed in animals, in which functional and behavioural changes were examined after sectioning of the corpus callosum. Bykov used Pavlovian conditioning in dogs to determine behavioural changes before and after sectioning of the corpus callosum (for translation see: [21]). Firstly, they identified that a conditioned response concerning one side of the body is automatically elicited when the opposite side is stimulated. Later Bykov
Hemispheric interaction
Split brain research provided an understanding of the importance of the corpus callosum during transfer of information between each isolated hemisphere. Especially lateralized processes that require interhemispheric cooperation, such as combining tactile information entering the right hemisphere with the speech process present in the left hemisphere became impossible by the complete removal of the corpus callosum, underlining its importance. Lateralization is thought to be an advantageous
Pathologies
The studies mentioned so far have investigated callosal function by means of its absence (the split brain studies and lesion studies) or its function in healthy individuals. However, looking at associations between altered morphology and disorders can also improve understanding of function. Altered corpus callosum morphology and function has been related to several (psychiatric) pathologies, such as schizophrenia, autism, ADHD, alien hand syndrome, personality disorders and bipolar affective
Discussion
The corpus callosum has proven to be an important structure in the human brain. Although it is possible to live without this white matter structure, it is required for a functional integration of cognitive and sensory information from one cerebral hemisphere to the other. How it regulates this transfer of information between cortical areas seems uncertain. In absence of this hemispheric communication behavioural abnormalities can occur, mainly due to the lateralization of brain function. Such
References (106)
- et al.
Fiber composition of the human corpus callosum
Brain Research
(1992) - et al.
Individual differences in brain asymmetries and fiber composition in the human corpus callosum
Brain Research
(1992) - et al.
A MRI quantitative study of corpus callosum in normal adults
Journal of Medical Colleges of PLA
(2008) - et al.
Anatomical-behavioral relationships: corpus callosum morphometry and hemispheric specialization
Behavioural Brain Research
(1994) - et al.
Diffusion tensor quantification of the human midsagittal corpus callosum subdivisions across the lifespan
Brain Research
(2008) - et al.
Sex differences in the corpus callosum with aging
Neurobiology of Aging
(1997) - et al.
Contribution of posterior corpus callosum to the interhemispheric transfer of tactile information
Cognitive Brain Research
(2005) The dynamics of interhemispheric collaboration and hemispheric control
Brain and Cognition
(1998)- et al.
Bykov and transfer between the hemispheres
Brain Research Bulletin
(2008) - et al.
Classical disconnection studies of the corpus callosum
Cortex
(2008)
Visual control of the arm, the wrist and the fingers: pathways through the brain
Neuropsychologia
Interhemispheric communication of visual learning
Neuropsychologia
Laterality effects in somesthesis following cerebral commissurotomy in man
Neuropsychologia
Interhemispheric control of manual motor activity
Behavioural Brain Research
Topography of the human corpus callosum revisited—comprehensive fiber tractography using diffusion tensor magnetic resonance imaging
Neuroimage
Intra- and interhemispheric processing of visual information in callosal agenesis
Neuropsychologia
Extent and limits of callosal plasticity: presence of disconnection symptoms in callosal agenesis
Neuropsychologia
The missing link: the role of interhemispheric interaction in attentional processing
Brain and Cognition
A parametric study of prefrontal cortex involvement in human working memory
Neuroimage
How dynamic is interhemispheric interaction? Effects of task switching on the across-hemisphere advantage
Brain and Cognition
Cortical excitability and interhemispheric inhibition after subcortical pediatric stroke: plastic organization and effects of rTMS
Clinical Neurophysiology
Transcranial magnetic stimulation in neurology
Lancet Neurology
The corpus callosum in dichotic listening studies of hemispheric asymmetry: a review of clinical and experimental evidence
Neuroscience and Biobehavioral Reviews
The neurotransmitters and postsynaptic actions of callosally projecting neurons
Behaviour and Brain Research
Functional significance of individual variations of callosal area
Neuropsychologia
Sound lateralization in subjects with callosotomy, callosal agenesis, or hemispherectomy
Cognitive Brain Research
Hemispheric metacontrol and cerebral dominance in healthy individuals investigated by means of chimeric faces
Cognitive Brain Research
Voxel-based analysis of white matter during adolescence and young adulthood
Brain & Development
Investigating the cortical origins of motor overflow
Brain Research Reviews
The effects of age and attention on motor overflow production—a review
Brain Research Reviews
Parallel interhemispheric processing in aging and alcoholism: relation to corpus callosum size
Neuropsychologia
Age-related changes in word retrieval: role of bilateral frontal and subcortical networks
Neurobiology of Aging
Depression and the hyperactive right-hemisphere
Neuroscience Research
Schizophrenia and the corpus callosum: developmental, structural and functional relationships
Behavioural Brain Research
Meta-analysis of magnetic resonance imaging studies of the corpus callosum in schizophrenia
Schizophrenia Research
Corpus callosum size and shape in first-episode affective and schizophrenia-spectrum psychosis
Psychiatry Research: Neuroimaging
Corpus callosum abnormalities and potential age effect in men with schizophrenia: an MRI comparative study
Psychiatry Research: Neuroimaging
Mapping corpus callosum deficits in autism: an index of aberrant cortical connectivity
Biological Psychiatry
Detecting corpus callosum abnormalities in autism based on anatomical landmarks
Psychiatry Research: Neuroimaging
Autism: the first firm finding = underconnectivity?
Epilepsy & Behavior
Callosal alien hand sign following a right parietal lobe infarction. Case reports
Journal of Clinical Neuroscience
The macrostructural and microstructural abnormalities of corpus callosum in children with attention deficit/hyperactivity disorder: a combined morphometric and diffusion tensor MRI study
Brain Research
Corpus callosum size and shape alterations in individuals with bipolar disorder and their first-degree relatives
Progress in Neuro-Psychopharmacology & Biological Psychiatry
Corpus callosum morphology and relationship to orbitofrontal and lateral ventricular volume in teenagers with first-presentation borderline personality disorder
Psychiatry Research: Neuroimaging
Diffusion weighted callosal integrity reflects interhemispheric communication efficiency in multiple sclerosis
Neuropsychologia
Corpus callosum function in verbal dichotic listening: inferences from a longitudinal follow-up of relapsing-remitting multiple sclerosis patients
Brain & Language
Surgical division of the commissural pathways in the corpus callosum. Relation to spread of an epileptic attack
Archives of Neurology and Psychiatry
Contribution of callosal connections to the interhemispheric integration of visuomotor and cognitive processes
Neuropsychology Review
Association, commissural, and projection pathways and their functional deficit reported in literature
Journal of Computer Assisted Tomography
The corpus callosum, the other great forebrain commissures, and the septum pellucidum: anatomy, development, and malformation
Neuroradiology
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