Utilizing Acoustic Features of Mammalian Vocalizations to Index the State of the Autonomic Nervous System

The evolution of the autonomic nervous system provides an organizing principle to interpret the adaptive significance of physiological systems in promoting social behavior and responding to social challenges. Notably, this phylogenetic shift in neural regulation of the ANS in mammals has produced a neuroanatomically linked social engagement system, intimately involved with behaviors such as facial expression, hearing, and vocalization, to encompass the richness of both social expressions and social experiences. Mammalian vocalizations, in particular, are assumed to be part of a conspecific social communication, with several mammalian species, including humans, modulating their acoustic features of vocalizations to signal affective state. At the clinical level, for example, pediatricians interpret high pitch infant cries as indicators of compromised health and/or distress. Importantly, this covariation between physiological state and the acoustic frequencies of vocalizations is neurophysiologically based. However, minimal investigation has centered on vocal prosody’s relation to autonomic state, or its potential interpretation as a health or physiological factor. To that end, this project employed the development of a dynamic, computation-based tool capable of rapidly detecting and characterizing the features of vocalizations. This automated system was further applied to humans as well as the highly social animal model, the prairie vole (Microtus ochrogaster) to demonstrate the covariation of several prosodic features with autonomic state. Overall, this is the first study demonstrating the utility of vocal prosody as a sensitive index of mammalian autonomic activity, further quantifiable using the novel, high-throughput tool developed here.