Studies on locomotion concern the mechanisms and systems associated with initiation and generation of movement in animals. The nervous system controls locomotion through neural networks that can be compared to computer circuits. Unlike computer circuits, neural networks exhibit a plasticity to adjust functionally so they can speed up or slow down in different behavioral situations. It is believed that movements would look robot-like without such plasticity. Neuromodulators such as the biogenic amine serotonin (5-HT) participate in maintaining the plasticity of neural networks. The specificity of 5-HT actions is based on the expression of seven 5-HT receptor subtypes in the cell membrane of individual neurons throughout the nervous system.
A zebrafish 5-HT2-like receptor was cloned and its role in the locomotion of zebrafish larvae will be explored. The zebrafish, Danio rerio, has become an attractive animal model for studies on locomotion because this fish exhibits simple motor patterns and has a simple nervous system. Activity of multiple neurons can be monitored in intact animals using optical recording techniques. Moreover, mutants can be generated and molecular tools such a genome map and database are available. However, the 5-HT system in the zebrafish is not well understood. As outlined in this proposal, mapping of the expression of the new zebrafish 5-HT receptor in the brain and spinal cord, pharmacological characterization of the zebrafish 5-HT receptor, and identification of 5-HT receptor expressing neurons in the pectoral fin motor pathway of zebrafish larvae will allow the construction of a model for the function of 5-HT receptors on the generation of pectoral fin movements. These studies will contribute to a better understanding of mechanisms underlying the orchestration of neuronal activity in a simple vertebrate brain.