Vocal Error Monitoring in the Primate Auditory Cortex.

Sensory-motor control requires the integration and monitoring of sensory feedback resulting from our behaviors. This self-monitoring is thought to result from comparisons between predictions about the expected sensory consequences of action and the feedback actually received, resulting in activity that encodes feedback error. Although similar mechanisms have been proposed during speech and vocal production, including sensitivity to experimentally perturbed auditory feedback, evidence for a vocal "error signal" has been limited. Here, we recorded from the auditory cortex of vocalizing nonhuman primates, using real-time frequency shifts to introduce feedback errors of varying magnitude and direction. We found neural activity that scaled with the magnitude of feedback error in both directions, consistent with vocal error monitoring at both the individual unit and population levels. This feedback sensitivity was greater than expected based upon passive sensory responses and was specific for units in the vocal frequency range. Feedback responses also predicted subsequent compensatory changes in vocal production. These results provide evidence that the auditory cortex encodes the degree of vocal feedback error using both unit-level error calculations and changes in the population of neurons involved. These mechanisms may provide critical error information necessary for feedback-dependent vocal control.