NEURAL CIRCUITS MEDIATING INNATE BEHAVIORS IN LARVAL ZEBRAFISH

Abstract

Animals exhibit several innate defense behaviors essential for survival, that are developed and refined through evolution. For the behaviors to be effective, the nervous system must be able to detect cues that signify potential danger and generate an appropriate response. Here, in larval zebrafish, we investigate defense behaviors to visual and olfactory stimuli that represent potential threat. In the first case, we investigate the neural circuitry mediating innate dark avoidance. Using state of the art tools, we provide evidence for a circuit from the retina and thalamus to serotonergic raphe neurons that controls preference for light over darkness. In the second case, we investigate if larvae react to chemicals released from the skin of an injured conspecific, which drive defensive behaviors in adults. We observe that larval fish freeze with extreme fear upon exposure and set the stage to delineate the neural circuitry mediating this behavior.