The auditory representation of speech sounds in human motor cortex
Connie Cheung,
Liberty S Hamilton,
Keith Johnson,
Edward F Chang
Affiliations
Connie Cheung
Graduate Program in Bioengineering, University of California, Berkeley-University of California, San Francisco, San Francisco, United States; Department of Neurological Surgery, University of California, San Francisco, San Francisco, United States; Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, United States; Department of Physiology, University of California, San Francisco, San Francisco, United States
Department of Neurological Surgery, University of California, San Francisco, San Francisco, United States; Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, United States; Department of Physiology, University of California, San Francisco, San Francisco, United States
Keith Johnson
Department of Linguistics, University of California, Berkeley, Berkeley, United States
Graduate Program in Bioengineering, University of California, Berkeley-University of California, San Francisco, San Francisco, United States; Department of Neurological Surgery, University of California, San Francisco, San Francisco, United States; Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, United States; Department of Physiology, University of California, San Francisco, San Francisco, United States
In humans, listening to speech evokes neural responses in the motor cortex. This has been controversially interpreted as evidence that speech sounds are processed as articulatory gestures. However, it is unclear what information is actually encoded by such neural activity. We used high-density direct human cortical recordings while participants spoke and listened to speech sounds. Motor cortex neural patterns during listening were substantially different than during articulation of the same sounds. During listening, we observed neural activity in the superior and inferior regions of ventral motor cortex. During speaking, responses were distributed throughout somatotopic representations of speech articulators in motor cortex. The structure of responses in motor cortex during listening was organized along acoustic features similar to auditory cortex, rather than along articulatory features as during speaking. Motor cortex does not contain articulatory representations of perceived actions in speech, but rather, represents auditory vocal information.
