Sensory Modulation of Motor Patterns

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Motor responses can be modified by incoming sensory information. In this award, Dr. Kiisa Nishikawa will study the way in which the brain uses incoming sensory input to modify motor output so that it becomes appropriate to its current context. The approach for solving this fundamental problem will use anuran feeding responses as a model system. Much is already known about the neural circuits associated with these responses, and about sensory processing of stimuli associated with the prey object. However, the processes by which motor output is matched to sensory input remain to be elucidated. The motor responses require accurate sensory recognition and precise localization of the objects as they move through the visual field. Once these processes of recognition and localization have been carried out, the brain must produce an appropriate motor response oriented in the correct direction at the correct distance, and the response must occur within a time period short enough to insure prey capture. In these experiments, the sensory feedback systems associated with prey capture will be characterized by (1) describing the anatomy of sensory receptors and their central projections using neuronal tracing and immunohistochemical staining; (2) determining the pattern of sensory activity during normal feeding using extracellular recording from dorsal roots and peripheral nerves; (3) elucidating how sensory input modulates motor output using deafferentation and afferent stimulation experiments. Feeding motor patterns will be studied using high-speed videography, electromyography and extracellular recording from peripheral nerves. This study will contribute to an understanding of the neural basis of adaptive responses and sensory-motor integration.