Neurophysiological evidence of differential mechanisms involved in producing opposing and following responses to altered auditory feedback

Objective: When hearing perturbations in voice auditory feedback, people produce responses that mostly oppose the perturbation direction, whereas a few responses follow the direction of feedback perturbation. The causes of opposing and following responses, however, remain poorly understood. The present event-related potential (ERP) study sought to examine the neurophysiological processing of opposing and following responses to pitch feedback perturbations during self-monitoring of vocal production.

Method: Twelve Mandarin-native speakers participated in the experiment. Vocal and neurophysiological responses to pitch perturbations (± 50 and ± 200 cents) in voice auditory feedback were measured. Individual-trial responses were categorized according to the response direction and then separately averaged in groups of opposing and following responses. ERPs indexed by the P1-N1-P2 complex corresponding to two types of vocal responses were also obtained.

Results: Opposing and following vocal responses did not differ in the magnitude, but there were greater proportions of opposing to following responses to 50 cents stimuli. The amplitude and latency of the P1 and N1 components showed none of significance across conditions, whereas there was a direction × magnitude effect on the P2 response. Following responses elicited greater P2 amplitudes than opposing responses only when pitch feedback was perturbed for downward 200 cents, and upward pitch perturbation elicited greater P2 amplitudes than those with downward direction only in the production of opposing responses.

Conclusion: These findings demonstrate that cortical processing of opposing responses is different from that of following responses, which can be modulated by the physical properties of feedback perturbation.

Significance: Different neural mechanisms are involved in the production of opposing and following responses to feedback perturbations during self-monitoring of vocal production.