IBN 98-08887 ROBERTS. The ultimate goal of this project is to understand how the nervous system accurately stores and processes the temporal flow of sensory information. The project focuses on the mormyrid electric fish; a nocturnal fish that senses its environment by emitting a weak electric pulse and then detecting the distortions caused by external objects with electrosensory receptors in its skin. This electrosensory system requires exceptional timing and precision in order for the fish to navigate through its environment and identify external objects. The site of initial electrosensory information processing is the electrosensory lateral line lobe (ELL). Neurons of the ELL are affected not only by electrosensory input, but also by signals that are temporally locked to the motor command that elicits the electric pulse. The responses of these neurons in the ELL are found to be highly adaptable to changing conditions that effect the electrosensory system. This adaptability leads to the ability of these neurons to "store" an image of the fish's expectation of its own electrical signal. However, due to the complexity of the ELL, it is unclear whether the rules of adaptive learning measured in certain experimental conditions can explain the collective neural activity observed under other experimental conditions. The difficulty of experimentally exploring the roles of various synaptic learning rules, sites of adaptive change, and intracellular connections make theoretical and modeling work a necessary adjunct to experimental study. This research effort is in collaboration with Dr. Curtis Bell who will provide data from experiments performed in his lab. Dr. Roberts will use mathematical analyses and computer simulations to combine results from different experiments to predict changes in the responses neurons in the ELL during changing sensory conditions. These predictions will then be used to test different mechanisms that may be responsible for the adaptiv e changes observed in the ELL. Completion of the proposed research will clarify underlying mechanisms of ELL function and illuminate the cooperative interactions of subsystems in this and other cerebellum-like structures.
