Title: Neuroethology of the zebrafish
Description: The complexity of the animal brain begs for simple tools that will assist scientists attempting to unravel the beautifully entangled mess. I begin by describing an experimental strategy for indentifying the components of neural circuits that control innate behaviors. My approach emphasizes the role of behavior analysis and the insights offered by neuroethology. While describing the neuroethological strategy, I will introduce the larval zebrafish and tools that I have developed to study the neural basis of innate visual behavior. The second chapter reports an implementation of the strategy that successfully revealed components of the circuit underlying the zebrafish optomotor reflex. We discovered distinct subsets of spinal projection neurons that were responsible for directing the swims and turns that constitute an important visual response to whole-field motion. The success of this study relied on the ability to record behavior-related neural activity in a restrained zebrafish, but this was found to be difficult for other visual behaviors. The third chapter addresses this problem by describing a novel technique to monitor neural activity in an unrestrained, behaving zebrafish. Employing the bioluminescent calcium reporter, Aequorin, we were able to detect the activity of Hypocretin neurons in freely swimming zebrafish. The success of this technique will allow an extensive survey of how identified populations of neurons collectively choreograph the complex behavior patterns of a developing vertebrate.
Subjects: Zebra danio, Animal behavior