Language production: electroencephalographic localization in the normal human brain.

Slow negative potentials, which are at a maximum over Broca's area in the left hemisphere, were recorded when normnal subjects spontaneously produced polysyllabic words. Bilaterally symmetrical potentials were seen with analogous, nonspeech control gestures. These potentials began up to 1 second before word or gesture articulation. These results are the first demonstration of localization of language production in normal human brain.