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Abstract:
4. Department of Psychology, University of Washington Recent
studies have suggested that language function in the cortex may be
more widely distributed than previously assumed. The present study
examines data from electrical cortical stimulation mapping (CSM)
from 14 patients with intractable epilepsy. A comprehensive
error-coding scheme, coupled with three-dimensional MR
reconstructions of individual patients' brains, affords a
characterization of functional/anatomical specificity. Slides of
common objects were used to evaluate naming functions. Stimulation
using bipolar electrode (5 mm, 2-8mv., 1 second) was used to induce
short lasting functional lesions. We tabulated the frequency,
location and nature of error types. Semantic paraphasia was most
common, followed by phonological reductions, phonological
paraphasia, neologisms and semantic/phonological blends. Semantic
paraphasias were evidenced across wide regions of cortex.
Phonological paraphasias were more limited in extent and found with
stimulation to the superior and middle temporal gyri (STG, MTG),
supramarginal gyrus and the inferior frontal gyrus. Phonological
reductions were the most regionally specific and associated with
posterior STG, MTG, and ITG, with a surprising lack of frontal lobe
involvement. These data suggest that lexical semantic functions may
be distributed throughout the left hemisphere and that phonological
functions may respect a more regional specialization. The data are
discussed in relation to proposals arguing for ventral/dorsal
dichotomy of speech function. Supported by NIH-DC02310,
NIH-DC03099, NS-35627 and the Pew-McDonnell Foundation.
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