Differential representation of articulatory gestures and phonemes in motor, premotor, and inferior frontal cortices

Abstract

Speech is a critical form of human communication and is central to our daily lives. Yet, despite decades of study, an understanding of the fundamental neural control of speech production remains incomplete. Current theories model speech production as a hierarchy from sentences and phrases down to words, syllables, speech sounds (phonemes) and the movements of speech articulator muscles used to produce these sounds (articulatory gestures). Here, we investigate the cortical representation of articulatory gestures and phonemes in speech motor, premotor, and inferior frontal cortices. Our results indicate that primary motor and premotor areas represent gestures to a greater extent than phonemes, while inferior frontal cortex represents both gestures and phonemes. These findings suggest that the cortical control of speech production shares a common representation with that of other types of movement, such as arm and hand movements.