Simulating single word processing in the classic aphasia syndromes based on the Wernicke–Lichtheim–Geschwind theory  

Oleh:

Weems, Scott A. ; Reggia, James A.

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: Brain and Language (Full Text) vol. 98 no. 3 (2006), page 291-309.
Topik: Neural network model; Aphasia; Hemispheric specialization; Word repetition; Confrontation naming; Computer model
Fulltext: 98_03_Weems.pdf (836.4KB)

Isi artikel

The Wernicke–Lichtheim–Geschwind (WLG) theory of the neurobiological basis of language is of great historical importance, and it continues to exert a substantial influence on most contemporary theories of language in spite of its widely recognized limitations. Here, we suggest that neurobiologically grounded computational models based on the WLG theory can provide a deeper understanding of which of its features are plausible and where the theory fails. As a first step in this direction, we created a model of the interconnected left and right neocortical areas that are most relevant to the WLG theory, and used it to study visual-confrontation naming, auditory repetition, and auditory comprehension performance. No specific functionality is assigned a priori to model cortical regions, other than that implicitly present due to their locations in the cortical network and a higher learning rate in left hemisphere regions. Following learning, the model successfully simulates confrontation naming and word repetition, and acquires a unique internal representation in parietal regions for each named object. Simulated lesions to the language-dominant cortical regions produce patterns of single word processing impairment reminiscent of those postulated historically in the classic aphasia syndromes. These results indicate that WLG theory, instantiated as a simple interconnected network of model neocortical regions familiar to any neuropsychologist/ neurologist, captures several fundamental ‘‘low-level’’ aspects of neurobiological word processing and their impairment in aphasia.

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