THE EFFECT OF SOCIAL EXPERIENCE ON THE SYNERGISTIC NEUROMODULATION OF MOTOR CIRCUITS

Abstract

Forming social groups is a critical adaptive strategy for the survival of many animal species, where conflict between members can result in dominance relationships. Dominance relationships are often formed through aggressive interactions and influence the cognitive and physiological properties of individuals in a status-dependent manner. The aim of this dissertation is to discern how zebrafish utilize aggression and visual cues to reinforce a stable dominance relationship, and what effect stable dominance has on the neurobiological processes underlying motor behavior, with a focus on dopamine signaling. Dopamine has been implicated in aggression, social regulation, and modulation of motor circuits, making it a central point of study regarding the relationship between social dominance and motor behavior. Using behavioral, pharmacological, and genetic approaches, I have found that (1) in addition to physical aggression, zebrafish alter their stripe coloration intensity to reinforce dominance, (2) stable dominance alters dopamine signaling through decreased expression of the dopamine transporter and the dopamine receptor type-1b, (3) changes in dopamine signaling manifest in altered escape and swimming locomotor behavior, and (4) dopamine acts synergistically with other neurotransmitters to regulate status-dependent motor circuit activation. Results from this dissertation have provided evidence for how stable dominance impacts modulation of motor circuits, revealing how changes in relative excitability of multiple neuromodulatory inputs provide a mechanism for the nervous system to adapt to changes in social conditions and allow animals to select a socially appropriate behavioral response.