The Essential Role of Premotor Cortex in Speech Perception

Besides the involvement of superior temporal regions in processing complex speech sounds, evidence suggests that the motor system might also play a role [1-4]. This suggests that the hearer might perceive speech by simulating the articulatory gestures of the speaker [5, 6]. It is still an open question whether this simulation process is necessary for speech perception. We applied repetitive transcranial magnetic stimulation to the premotor cortex to disrupt subjects' ability to perform a phonetic discrimination task. Subjects were impaired in discriminating stop consonants in noise but were unaffected in a control task that was matched in difficulty, task structure, and response characteristics. These results show that the disruption of human premotor cortex impairs speech perception, thus demonstrating an essential role of premotor cortices in perceptual processes.