Disconnexion Syndromes in Animals and Man

Geschwind, Norman

doi:10.1093/brain/88.3.585

Cited by 1,418 publications

(363 citation statements)

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“…This suggests an expansion of the extent of area Tpt in modern humans and may represent a species-specific configuration indicative of greater connections with and extension into the parietal lobe association cortex. This region is the site of major cross-modality integration and, as argued by Geschwind (1965), is an important component for the foundation for human language. This phyletic variation in parietotemporal cortex anatomy may also be linked to differences in cross-modal perception among monkeys, apes and humans.…”

Section: Discussionmentioning

confidence: 96%

Wernicke's area homologue in chimpanzees (Pan troglodytes) and its relation to the appearance of modern human language

et al. 2010

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Human language is distinctive compared with the communication systems of other species. Yet, several questions concerning its emergence and evolution remain unresolved. As a means of evaluating the neuroanatomical changes relevant to language that accompanied divergence from the last common ancestor of chimpanzees, bonobos and humans, we defined the cytoarchitectonic boundaries of area Tpt, a component of Wernicke's area, in 12 common chimpanzee brains and used designbased stereologic methods to estimate regional volumes, total neuron number and neuron density. In addition, we created a probabilistic map of the location of area Tpt in a template chimpanzee brain coordinate space. Our results show that chimpanzees display significant population-level leftward asymmetry of area Tpt in terms of neuron number, with volume asymmetry approaching significance. Furthermore, asymmetry in the number of neurons in area Tpt was positively correlated with asymmetry of neuron numbers in Brodmann's area 45, a component of Broca's frontal language region. Our findings support the conclusion that leftward asymmetry of Wernicke's area originated prior to the appearance of modern human language and before our divergence from the last common ancestor. Moreover, this study provides the first evidence of covariance between asymmetry of anterior and posterior cortical regions that in humans are important to language and other higher order cognitive functions.

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Section: Discussionmentioning

confidence: 96%

Wernicke's area homologue in chimpanzees (Pan troglodytes) and its relation to the appearance of modern human language

et al. 2010

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“…The localization of language functions was then challenged by the holistic theory, which posited a single language function performed by the left hemisphere (review in [49]). Geschwind [50,51] reconsidered localization and proposed that the impairments were the result of disconnection between brain areas (review in [52]). …”

Section: Clinical Description and Originalmentioning

confidence: 99%

A neuropsychological perspective on the link between language and praxis in modern humans

Roby-Brami

Hermsdörfer

Roy

et al. 2012

Phil. Trans. R. Soc. B

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6University Claude Bernard Lyon 1, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne, FranceHypotheses about the emergence of human cognitive abilities postulate strong evolutionary links between language and praxis, including the possibility that language was originally gestural. The present review considers functional and neuroanatomical links between language and praxis in brain-damaged patients with aphasia and/or apraxia. The neural systems supporting these functions are predominantly located in the left hemisphere. There are many parallels between action and language for recognition, imitation and gestural communication suggesting that they rely partially on large, common networks, differentially recruited depending on the nature of the task. However, this relationship is not unequivocal and the production and understanding of gestural communication are dependent on the context in apraxic patients and remains to be clarified in aphasic patients. The phonological, semantic and syntactic levels of language seem to share some common cognitive resources with the praxic system. In conclusion, neuropsychological observations do not allow support or rejection of the hypothesis that gestural communication may have constituted an evolutionary link between tool use and language. Rather they suggest that the complexity of human behaviour is based on large interconnected networks and on the evolution of specific properties within strategic areas of the left cerebral hemisphere.

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“…Geschwind's tour de force 1965 publication Disconnexion Syndromes in Animal and Man reintroduced functional disconnection syndromes to the neurosciences spurring decades of research aimed at understanding the interplay between primary and association centers of brain function (Geschwind, 1965a(Geschwind, , 1965b. This work bridged classical and "neo" associationism and, although several of the primary tenets were significantly refined over time, (see Damasio & Galaburda, 1985;Mesulam, 1985), disconnection syndromes have been a central area of research in the clinical neurosciences since that time.…”

Section: Introduction: Disconnecting the Brainmentioning

confidence: 99%

Hyperconnectivity is a fundamental response to neurological disruption.

et al. 2015

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Objective: In the cognitive and clinical neurosciences, the past decade has been marked by dramatic growth in a literature examining brain "connectivity" using noninvasive methods. We offer a critical review of the blood oxygen level dependent functional MRI (BOLD fMRI) literature examining neural connectivity changes in neurological disorders with focus on brain injury and dementia. The goal is to demonstrate that there are identifiable shifts in local and large-scale network connectivity that can be predicted by the degree of pathology. We anticipate that the most common network response to neurological insult is hyperconnectivity but that this response depends upon demand and resource availability. Method: To examine this hypothesis, we initially reviewed the results from 1,426 studies examining functional brain connectivity in individuals diagnosed with multiple sclerosis, traumatic brain injury, mild cognitive impairment, and Alzheimer's disease. Based upon inclusionary criteria, 126 studies were included for detailed analysis. Results: Results from 126 studies examining local and whole brain connectivity demonstrated increased connectivity in traumatic brain injury and multiple sclerosis. This finding is juxtaposed with findings in mild cognitive impairment and Alzheimer's disease where there is a shift to diminished connectivity as degeneration progresses. Conclusion: This summary of the functional imaging literature using fMRI methods reveals that hyperconnectivity is a common response to neurological disruption and that it may be differentially observable across brain regions. We discuss the factors contributing to both hyper-and hypoconnectivity results after neurological disruption and the implications these findings have for network plasticity.

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Disconnexion Syndromes in Animals and Man

Cited by 1,418 publications

References 0 publications

Wernicke's area homologue in chimpanzees (Pan troglodytes) and its relation to the appearance of modern human language

Wernicke's area homologue in chimpanzees (Pan troglodytes) and its relation to the appearance of modern human language

A neuropsychological perspective on the link between language and praxis in modern humans

Hyperconnectivity is a fundamental response to neurological disruption.

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