Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.06.138263v1?rss=1 Authors: Tachibana, R. O., Xu, M., Hashimoto, R.-i., Homae, F., Okanoya, K. Abstract: Our motor system uses sensory feedback to keep behavioral performance in desired status. From this view, motor fluctuation is not simply 'noise' inevitably caused in the nervous system, but should provide a role in generating variations to explore better outcomes via their sensory feedback. Vocal control system offers a good model to investigate such adaptive sensory-motor interactions. The pitch, or fundamental frequency (FF), of voice is adaptively regulated by hearing its auditory feedback to compensate FF deviations. Animal studies, particularly for songbirds, have demonstrated that the variability in vocal features contributes to the adaptive control, although the same issue in human vocalizations has remained unclear. Here, we tested whether and how the motor variability contributes to adaptive control of vocal FF in humans. We measured the amount of compensatory vocal responses against FF shifts in the auditory feedback, and quantified the motor variability as amplitudes of spontaneous FF fluctuations during no shift vocalizations. The result showed a positive correlation between the ratio of compensation and the spontaneous vocal variability. Further analysis indicated that this correlation was due to slowly fluctuating components (<5 Hz) of the variability, but not fast fluctuations (6-30 Hz), which is likely to reflect controllability from the central nervous system. Moreover, the compensatory responses consisted of the same frequency range with the slow component in the spontaneous variability. These findings consistently demonstrated that the spontaneous motor variability predicts the adaptive control in vocal FF, supporting the motor exploration hypothesis. Copy rights belong to original authors. Visit the link for more info