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Norman Geschwind (1926–1984)
Published in Andrew P. Wickens, Key Thinkers in Neuroscience, 2018
According to Geschwind, a disconnection syndrome occurs when a lesion of the myelinated white matter occurs to the commissural fibres, or to the association pathways within a hemisphere. In formulating this theory, Geschwind strongly emphasised the work of German Paul Flechsig who had established certain laws of cortical connectivity in 1901. Flechsig had shown that the primary sensory areas of the cortex (visual auditory, etc.) only make connections with their own respective adjacent unimodal association areas. But in turn, these areas project to higher order polymodal association areas (“the association areas of the association areas”) that have a rich array of connections with many other regions of the cerebral cortex (and limbic system). This principle also applied to the linkages between the two hemispheres, since the fibres that pass through the corpus callosum derive from areas of secondary association cortex. Geschwind further stressed that the human brain is unique because of its rich intra-connectivity between association areas (a feature that does not occur in other animals whose cortex is more richly connected with the limbic system). Thus, for Geschwind, knowledge of this wiring is profoundly important for a functional understanding of the human brain and being able to accurately diagnose clinical syndromes arising from its damage.
Creativity and positive psychology in psychotherapy
Published in International Review of Psychiatry, 2020
The lack of neuronal coherence, also referred to as neuronal connectivity, seems to be associated with mental disorders (Bassett & Bullmore, 2009). In schizophrenia, for instance, we know that the critical factor is not a circumscribed brain lesion but rather a distributed impairment involving many cortical areas and their connectivity (Uhlhaas & Singer, 2010). The last-named authors speak of a disconnection syndrome as the expression of disturbed coherence. This conception is very similar to the classical phenomenological view that mental incoherence is a characteristic trait and state in schizo-typical psychosis. In posttraumatic stress disorder and in some depressive disturbances, the neural systems associated with emotions are disconnected from the neural systems associated with cognition. This reminds us of Freud’s intuitive conviction Freud that certain mental disorders, cognition and the emotions are disconnected.
Disorders of consciousness terminology: history, evolution and future directions
Published in Brain Injury, 2019
Nathan D. Zasler, Marta Aloisi, Marianna Contrada, Rita Formisano
The term “apallic syndrome” was first proposed by Kretschmer in 1940 (8) and then extensively described in all its complexity in Franz Gerstenbrand’s 1967 monograph (9). This same nomenclature was more recently reintroduced in the European Guidelines on Vegetative State/Apallic Syndrome in 2007 (10). This term was used as a functional definition of a cortical disconnection syndrome, i.e., the lack of cortical control on the subcortical and brainstem functions. The term “coma vigil” was widely accepted and disseminated in the French literature (11), as a descriptor of the dichotomy between the “presence of vigilance and absence of consciousness”. In 1972, Jennett and Plum (12) first proposed the terminology of Vegetative State (VS), defined as a condition that follows the acute phase of coma and is distinguished by the presence of eye-opening and some recovery of sleep-wake cycles with no demonstrable behavioral evidence of awareness (12).
Cognitive and physical disability in Egyptian patients with multiple sclerosis: genetic and optical coherence tomography study
Published in Neurological Research, 2019
Maged Abdel Naseer, Shereen Fathi, Nagwa K Roshdy, Dalia M Labib, Dalia H. Khalil, Walaa Ibrahim, Rehab Magdy
All these results suggest a strong association between MS disability process and each of cognitive dysfunction and OCT abnormality. However, the only predictor of progressive disability revealed by regression analysis was the SDMT, a measure for information processing speed. Performance in information processing speed is highly dependent on the white matter integrity of several brain networks. For this reason, the impairment in SDMT performance might reflect more widespread brain damage based on the concept of disconnection syndrome seen in MS [28]. The result of this study is in line with Benedict, DeLuca [29] who recommend SDMT as the best neurocognitive test in reliability and sensitivity to MS disease, as it was the only one showed consistent correlation with EDSS in both remissions and relapses periods. Complementary to this result, our study revealed that educational level was the only predictor of cognitive dysfunction assessed by SDMT. So, we can conclude that lifetime intellectual enrichment may protect MS patients from cognitive impairment and thus limiting their physical disability. The later was proved via this study by the significant correlation found between years of education and thickness of both RNFL and GCC, which means that higher educational level was associated with lesser axonal loss expressed by OCT.