Some functional effects of sectioning the cerebral commissures in man*

Gazzaniga, Michael S.; Bogen, Joseph E.; Sperry, R. W.

doi:10.1073/pnas.48.10.1765

Cited by 342 publications

(142 citation statements)

References 8 publications

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“…Before such research, the complete severing of the corpus callosum had surprisingly little observable effect on the behavior of these patients in the real world. Not until Gazzaniga et al (1) tested the patients using lateralized procedures did we come to appreciate the full extent to which the two hemispheres are specialized for different functions. This separation of function implies that ongoing cognitive and perceptual processing is dynamically integrated between specialized brain modules.…”

Section: Discussionmentioning

confidence: 99%

“…community detection | network dynamics | split-brain | temporal network | neural oscillations T he field of split-brain research began several decades ago with the use of a drastic surgical solution for intractable epilepsy (1)(2)(3): the severing of the corpus callosum. This procedure significantly decreased the connectivity between the hemispheres, thereby irrevocably altering interhemispheric communication.…”

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confidence: 99%

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Dynamic network structure of interhemispheric coordination

Doron

Bassett

Gazzaniga

2012

Proc. Natl. Acad. Sci. U.S.A.

136

146

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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. These techniques enable the characterization of dynamic changes in the brain's functional connectivity, thereby providing an unprecedented means of decoding interhemispheric communication. Here, we illustrate the use of these techniques to examine interhemispheric coordination in healthy human participants performing a split visual field experiment in which they process lexical stimuli. We find that interhemispheric coordination is greater when lexical information is introduced to the right hemisphere and must subsequently be transferred to the left hemisphere for language processing than when it is directly introduced to the language-dominant (left) hemisphere. Further, we find that putative functional modules defined by coherent interhemispheric coordination come online in a transient manner, highlighting the underlying dynamic nature of brain communication. Our work illustrates that recently developed dynamic, network-based analysis techniques can provide novel and previously unapproachable insights into the role of interhemispheric coordination in cognition.T he field of split-brain research began several decades ago with the use of a drastic surgical solution for intractable epilepsy (1-3): the severing of the corpus callosum. This procedure significantly decreased the connectivity between the hemispheres, thereby irrevocably altering interhemispheric communication. Although a few interhemispheric pathways remained through subcortical structures and the anterior commissure, examination of callosal function using split visual field experiments clearly demonstrated its role in interhemispheric communication (2). The callosal projection plays a particularly crucial role in a variety of sensory-motor integrative functions of the two hemispheres (4), shows changes with age, and demonstrates the potential for dynamic changes with training (5). In fact, experiments in patients with severance of the callosum revealed that it subserves a large range of behaviors and cognitive functions that underlie the varied workings of the mind.Interhemispheric communication has been studied using two basic approaches. The first uses behavioral experiments to examine cognitive phenotypes, and the second uses neuroscientific experiments to examine brain phenotypes. Split-brain research initially focused on the former: Patients demonstrated striking behavioral phenotypes that provided clues regarding the underlying mechanics of brain communication. For example, although most perceptual processing appears to be isolated in each hemisphere following surgery, some attentional and emotional mechanisms initiated in one hemisphere can still be communicated to the other, cortically disconnected,...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Dynamic network structure of interhemispheric coordination

Doron

Bassett

Gazzaniga

2012

Proc. Natl. Acad. Sci. U.S.A.

136

146

View full text Add to dashboard Cite

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“…However, the findings of studies investigating hemispheric asymmetries in the selection of ambiguous word meanings have often been conflicting, in both neutral (e.g., Burgess & Simpson, 1988;Hasbrooke & Chiarello, 1998) and biasing contexts (e.g., Coney and Evans, 2000;Faust and Gernsbacher, 1996;Swaab et al, 1998;Tompkins et al, 2000). These studies have used either visual half-field (VF) presentation methods (Gazzaniga et al, 1962) with behavioral measures in neurologicallyintact individuals 1 , or behavioral or ERP measures with participants who have unilateral brain damage. Disparate findings have been observed both within and between participant populations.…”

Section: Hemispheric Asymmetries In Ambiguity Resolutionmentioning

confidence: 99%

The divided visual world paradigm: Eye tracking reveals hemispheric asymmetries in lexical ambiguity resolution

Meyer¹,

Federmeier²

2008

Brain Research

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Eye tracking was combined with the visual half-field procedure to examine hemispheric asymmetries in meaning selection and revision. In two experiments, gaze was monitored as participants searched a four-word array for a target that was semantically related to a lateralized ambiguous or unambiguous prime. Primes were preceded by a related or unrelated centrally-presented context word. In Experiment 1, unambiguous primes were paired with concordant weakly-related context words and strongly-related targets that were similar in associative strength to discordant subordinate-related context words and dominant-related targets in the ambiguous condition. Context words and targets were reversed in Experiment 2. A parallel study involved the measurement of event-related potentials (ERPs; Meyer, A. M., and Federmeier, K. D., 2007. The effects of context, meaning frequency, and associative strength on semantic selection: Distinct contributions from each cerebral hemisphere. Brain Res. 1183, 91-108). Similar to the ERP findings, gaze revealed context effects for both visual fields/hemispheres when subordinate-related targets were presented: initial gaze revealed meaning activation when an unrelated context was utilized, whereas later gaze also revealed activation in the discordant context, indicating that meaning revision had occurred. However, eye tracking and ERP measures diverged when dominant-related targets were presented: for both visual fields/hemispheres, initial gaze indicated the presence of meaning activation in the discordant context, and, for the right hemisphere, discordant context information actually facilitated gaze relative to unrelated context information. These findings are discussed with respect to the activeness of the task and hemispheric asymmetries in the flexible use of context information. KeywordsLexical Ambiguity; Cerebral Hemispheres; Context Effect; Eye Tracking Most English words are ambiguous (Rodd, Gaskell, and Marslen-Wilson, 2004), having either multiple unrelated meanings (homonymy) or multiple related senses (polysemy). For example, the homonym bank can refer to a financial institution or the edge of a river, and the polysemous word lamb can refer to food or a living animal. Lexical ambiguity has been the subject of much research over the past several decades; many studies (e.g., Duffy et al., 1988;Simpson, Corresponding Author: Aaron M. Meyer, Beckman Institute, University of Illinois, 405 N. Mathews Ave., Urbana, IL 61801, meyeram@uiuc.edu, (217) 244-9638. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 1981;Swinney and Hakes, 1976;Ta...

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“…After a corpus callosotomy for intractable epilepsy, patients appear to have a splitting of consciousness into two selves, each of which is contained in a different brain hemisphere. This has been termed split-brain syndrome (Gazzaniga et al 1962;Gazzaniga 1967). 4 The implications of split-brain syndrome have been discussed since the syndrome was first discovered yet there is no consensus on what happens to personal identity in each brain hemisphere (Gazzaniga 1967;Nagel 1971;Parfit 1984;Shoemaker 1984;Swinburne 1984).…”

Section: The Failure Of the Standard Approaches To Identitymentioning

confidence: 99%

Uploading and Branching Identity

Cerullo¹

2014

Minds & Machines

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If a brain is uploaded into a computer, will consciousness continue in digital form or will it end forever when the brain is destroyed? Philosophers have long debated such dilemmas and classify them as questions about personal identity. There are currently three main theories of personal identity: biological, psychological, and closest continuer theories. None of these theories can successfully address the questions posed by the possibility of uploading. I will argue that uploading requires us to adopt a new theory of identity, psychological branching identity. Psychological branching identity states that consciousness will continue as long as there is continuity in psychological structure. What differentiates this from psychological identity is that it allows identity to continue in multiple selves. According to branching identity, continuity of consciousness will continue in both the original brain and the upload after nondestructive uploading. Branching identity can also resolve long standing questions about split-brain syndrome and can provide clear predictions about identity in even the most difficult cases imagined by philosophers.

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Some functional effects of sectioning the cerebral commissures in man*

Abstract: Some of these studies have been reported in a preliminary communication, Hoffee, P., and E.

Cited by 342 publications

References 8 publications

Dynamic network structure of interhemispheric coordination

Dynamic network structure of interhemispheric coordination

The divided visual world paradigm: Eye tracking reveals hemispheric asymmetries in lexical ambiguity resolution

Uploading and Branching Identity

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