Electrical stimulation of Wernicke's area interferes with comprehension

Arrays of subdural electrodes were placed over the lateral convexity of the dominant hemisphere for propositional language in four patients with epilepsy as part of an evaluation prior to cortical resections. Stimulation was performed over several days. When we stimulated the posterior temporal language area, reading and comprehension of complex verbal information were impaired, but comprehension of nonverbal and simple verbal data was not affected. Impairment produced by stimulation seemed to be due to language comprehension difficulties, rather than impaired praxis or initial word storage.