Integration of Neuroendocrine and Vocal Mechanisms

Cornell University, Ithaca NY

Investigators

Abstract

These studies will identify how the neuropeptides (arginine vasotocin, AVT and isotocin, IT) and steroid hormones influence neural circuits that generate vertebrate social behaviors, in this case vocalization. The project will investigate: (1) the development and steroid-dependent plasticity of neuropeptide modulation of vocal-related neurons, and (2) the role of aromatase, an enzyme that converts testosterone to estradiol, in regulating steroid effects on vocal neurons either directly and/or indirectly via their influence on neuropeptides. The goals will be achieved using neurophysiological, neuroanatomical, biochemical and behavioral methods. Vocalization behaviors are central to mediating social interactions in animal groups as diverse as fish and humans. This lab studies the neuroendocrine control of vocalization in fish with two male types or morphs. Among midshipman fish, "singing" males court females with a "song", while "sneaking" males neither sing nor court females but instead steal fertilizations from singing males that have attracted females to their nest. Although all adults produce agonistic calls, sound production differs here too with social context for the male morphs and females. The neurophysiological properties of a pattern generator that establishes sex- and morph-typical vocalizations is directly influenced by the action of AVT and IT (the fish equivalents of arginine vasopressin and oxytocin in mammals) in the preoptic area-anterior hypothalamus, a brain region implicated in the control of social/vocal behaviors across all vertebrates. The pattern of AVT and IT modulation is dependent on social/vocal behavior, not gonadal sex. These patterns are also paralleled by differences in aromatase levels in vocal brain regions. Together, these findings provide a unique opportunity to investigate the separate and/or interactive effects of peptides and steroid hormones on brain circuitry that determines social behaviors.