The role of somatosensation in vocal motor control for singing

Abstract

Extensive research on the human voice with its sensory and motor systems has converged on the idea that the auditory system is critical for vocal production, yet recent reports suggest that the somatosensory system contributes more substantially to vocal motor-control than currently recognized. This thesis assessed the modulator influence of primary somatosensory cortex (S1) on vocal pitch-matching with transcranial magnetic stimulation, applied to right larynx-S1 and a dorsal-S1 control area in untrained singers. In experiment I, participants sang before and after TMS with normal auditory feedback whereas in experiment II, auditory feedback was masked with noise. TMS showed no effects on singing in experiment I. However, when auditory feedback was masked, larynx-S1 stimulation significantly improved both initial pitch accuracy and final pitch stability in contrast to dorsal-S1 stimulation. Positive effects of larynx S1 stimulation on initial and final pitch accuracy were more pronounced in participants who sang less accurately prior to iTBS. Moreover, masking showed more adverse effects on pitch-control in participants with higher pitch-discrimination thresholds. Conversely, these participants also profited more from larynx-S1 stimulation in initial and final-pitch accuracy. These data provide first evidence for a critical involvement of larynx-S1 in pitch motor-control independent from prior singing experience.