Inhibition of auditory cortical neurons during phonation.

The neuronal activity of the auditory cortex in the squirrel monkey was investigated during phonation in order to study relationships between brain structures involved in phonation and audition. Responses of single cells in the superior temporal gyrus were extracellularly recorded during stimulation by self-produced vocalizations (elicited either through electrical stimulation of the central gray or uttered spontaneously), and by tape-recorded vocalizations played back together with other species-specific cells. More than half of those cells which reacted to the play-back of self-produced vocalizations responded clearly weaker or not at all during phonation. Less than half of the neurons did not differentiate between self-produced and loudspeaker-transmitted vocalizations. It is concluded that brain structures which are activated during phonation exert an inhibitory influence on parts of the auditory cortex, a fact providing evidence of a neuronal feed-forward circuit mechanism within the process of audiovocal communication.