LARYNGEAL MUSCLE ACTIVITY AND RESPIRATORY DYNAMICS UNDERLYING VOCAL PITCH CONTROL IN MARMOSETS

Vocal pitch control relies on precise coordination between laryngeal muscles and respiratory dynamics, yet the neuromuscular mechanisms underlying natural vocal production remain poorly understood. In this study, we investigated the roles of the cricothyroid (CT) and thyroarytenoid (TA) muscles, key regulators of vocal pitch, during vocal communication in the common marmoset (Callithrix jacchus). Bipolar silver electrodes were chronically implanted in the CT and TA muscles to record electromyographic (EMG) activity, and simultaneous respiratory measurements were obtained using a custom-designed wearable jacket.
We found that both CT and TA muscles exhibit pre-vocal activation, suggesting that preparatory muscle tension is required to achieve the desired vocal pitch. During vocal production, we identified selective recruitment of muscle activation consistent with an energy-efficient strategy, in which laryngeal muscles are preferentially engaged during dynamic pitch modulation.
Together, these findings suggest that CT and TA activity provide a default motor pattern for vocal output, while respiratory drive and subglottal pressure act as gating mechanisms that enable or modulate vocal production. These results highlight the marmoset larynx as a highly specialized system supporting flexible and efficient vocal control across respiratory phases.