Neural basis of category-specific semantic deficits for living things: evidence from semantic dementia, HSVE and a neural network model.

Full Abstract

Studies of patients with semantic impairments following brain damage offer key insights into the cognitive and neural organization of semantic memory. Especially important in this regard are studies of category-specific semantic impairment. We report a direct comparison of semantic deficits in two groups suffering from different diseases:
semantic dementia (SD) and herpes simplex virus encephalitis (HSVE). Although pathology in both disorders is centred on the anterior temporal lobes bilaterally, category-specific semantic impairment is rarely observed in SD yet commonly found in HSVE. Using a combination of neuropsychology and computational neuroscience, we tested the possibility that category-specific deficits for living things depend not solely upon the location of damage within the cortical semantic network but also critically upon the type of impairment. When the semantic representations within the model are degraded or 'dimmed' then a generalized, global semantic impairment results (as found in SD) but when the representations are distorted then a category-specific pattern emerges (as per HSVE). Three novel predictions from this model were tested and confirmed, thereby adding weight to the hypothesis that both type and distribution of pathology can be critical in producing neuropsychological phenomena.

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Author information

Author/s: Lambon Ralph, Matthew A (MA); Lowe, Christine (C); Rogers, Timothy T (TT);

Affiliation: School of Psychological Sciences, University of Manchester, Manchester, UK. matt.lambon-ralph(-atsign-)manchester.ac.uk

Grants: MH64445 (Agency:NIMH NIH HHS)

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: Brain : a journal of neurology (Brain), published in England. (Language: eng)

Reference: 2007-Apr; vol 130 (issue Pt 4) : pp 1127-37

Dates: Created 2007/04/17; Completed 2007/05/30; Revised 2007/12/03;

PMID: 17438021, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Aphasia - pathology; psychology
Brain Injuries - pathology; psychology
Cohort Studies
Comprehension
Computer Simulation
Dementia - pathology; psychology
Encephalitis, Herpes Simplex - pathology; psychology
Humans

Humans
Language Disorders - pathology; psychology
Mental Recall
Models, Neurological
Neural Networks (Computer)
Neuropsychological Tests
Recognition (Psychology)
Temporal Lobe - pathology

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