ACOUSTIC BEHAVIOR--NEURAL AND DEVELOPMENTAL BASES

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One goal of this project is to investigate the neurobehavioral mechanisms of acoustic communication, particularly species-specific acoustic signals from potential mates or potential predators. Because of the relative simplicity of its auditory behavior and neural pathways in the CNS (compared to vertebrates), the cricket is an ideal model system for investigating the processing of auditory information into adaptive behavioral acts. Our research is directed at such questions as: (1) is auditory behavior under the control of single neurons, such as feature detectors or command neurons? (2) how does the animals's behavioral context determine the specific role that an auditory neuron plays in influencing particular auditory behaviors? (3) how is the auditory system organized to recognize the temporal pattern of species-specific mating calls, or to recognize the hunting calls of vocal predators (like bats)? (4) what is the role of courtship songs in mating behavior, and how are they processed in the auditory system? We hope to achieve a cellular analysis of auditory communication that can be combined with previous studies at the behavioral, genetic, and evolutionary levels of organization. The cricket auditory system is also ideal for the investigation of developmental questions. For example, how does the auditory system respond to the loss of an ear? The effects of auditory deprivation or deafferentiation can be studied in the level of single, identified neurons. 1) As in the case in other sensory systems, if the auditory nerve is sectioned, its axons can regenerate and restore function. 2) More unusually, compensatory growth in dendrites of sensory interneurons also restores auditory function. Does functional recovery involve synaptic competition for afferents among compensatory dendrites? Does the auditory afferent projection innervate ectopic dendritic projections by adding new terminal branches (and more synaptic space)? The auditory system of the cricket provides a system in which to study issues of synaptic plasticity such as dendritic and axonal sprouting, competition, and regeneration, at a cellular level through the analysis of single, identified neurons.