From EMG to frequency modulation in the zebra finch song

GOLLER, FRANZ; BUSH, ALAN; DÖPPLER, JUAN F.; MINDLIN, GABRIEL B.

Congreso; XXXII Congreso Anual de la Sociedad Argentina de Investigación en Neurociencias; 2017

Behavior requires the central nervous system (CNS) to control a set of biomechanical devices. The instructions from the CNS are electrical in nature, and need to be translated by these devices. In the case of birdsong, a delicate and fast control of a set of muscles is required to control the configuration of the syrinx (the avian vocal organ), and the respiratory system. In particular, the syringealis ventralis muscle (vS), controls the tension of the vibrating labia, which modulate the airflow to produce sound. However, the translation of the instructions into acoustical features is complex and species specific. In the case of zebra finch, although the mean fundamental frequency in a syllable is correlated to the mean electromyographic (EMG) activity of vS, it is not trivial to account for the fast frequency modulations, or to interpret bursts of activity between syllables.In this work we present a biomechanical model of the dynamics of the vS muscle and thelabia. The model is driven by the EMG activity of the vS muscle and allows to calculate thefrequency modulation produced by the stretching of the labia.We show that even using small segments of data, the parameters of the model can be fitted, and the predicted frequency for different types of syllables and frequency ranges is in agreement with the measured sound.