Abstract
Using cortical electrical stimulation, we investigated localization of language functions in patients with intractable epilepsy. Essential areas for various language functions were quite localized, but with considerable individual variation. Both anterior and posterior language areas were related to speech production and perception of language.
The presence of a basal temporal language area is indicated by cortical electrical stimulation, but aphasia is not elicited by lesions in this area. We examined the basal temporal language area by cortical stimulation and event-related potentials using subdural electrodes. Aphasic symptoms in a patient occurred during stimulation of the basal temporal area, which were always associated with intrastimulus remote discharges in the posterior language area. This finding suggested a close functional relationship between the basal temporal area and posterior language area. Electrocorticograms from the bilateral basal temporal cortices were recorded during lexical-decision and picture-naming tasks. Task-related high γ-Band activity was observed bilaterally during the naming task. In contrast, there was left dominance in the lexical-decision task. Distribution of high γ-Band activity was varied depending on the language task used.
Detailed mapping of language functions by cortical electrical stimulation and electrocorticograms is mandatory to explore the network for language in individual subjects and to prevent postoperative language deficits.
