Inhibitory control of speech production in the human premotor frontal cortex

Abstract

Natural speech is full of starts and stops. Here, we studied the neural mechanisms that underlie the inhibitory control of speech, specifically the ability to stop speaking on demand. We recorded direct cortical activity while participants made continuous speech production and were given a visual cue to stop speaking. Neural recordings revealed activity in the premotor frontal cortex associated with speech stopping. Cortical sites showing stop activity were largely distinct from sites involved in active speech production or, more specifically, encoding articulatory movements. Electrocortical stimulation mapping at many premotor sites with stop activity caused involuntary speech arrest, an immediate inability to speak or vocalize. Furthermore, many speech arrest sites did not co-localize with neural activity correlating with speech motor planning or execution, contrary to this long-assumed function in clinical brain mapping. Together, these results suggest a previously unknown premotor cortical network that underlies the inhibitory control of speech, which has significant implications for understanding the dynamics of normal and altered speech production, as well as clinical brain mapping.