Analysis of central synaptic mechanisms underlying behavioral context-dependent posture control in crustaceans10111147

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A novel type of optical telemetry was developed from scratch to record the spike activity of central neurons from the circumesophageal commissure of freely behaving animal in the water. The neural recording by the telemetry was accompanied by video recording of the animal body orientation, posture and behavior so that the recorded spike activity was analyzed in relation to ongoing behavior of the animal. It was revealed that 1) the spike activity of descending statocyst interneurons was dependent on whether the animal was quiescent or active in some interneurons but not in others, 2) some interneurons showed different spike activities to the same statocyst stimulation by body tilting depending on whether the animal was engaged in postural extension or flexion of the abdomen at the time of stimulation, and 3) the behavioral context-dependent spike activity in response to statocyst stimulation was consistent and unique to each individual interneuron. These findings demonstrate that the a … More ctivity of those interneurons conveying statocyst information from the brain to motor centers in the thoracic ganglia (for walking legs) and abdominal ganglia (for pleopods including uropods) varies depending on the behavioral condition and context of the animal, suggesting that the crustacean posture control is not based on simple reflexes but is a highly adaptive behavior based on the variable response characteristics of descending statocyst interneurons. The telemetry experiment was further extended to analyze the spike activities of central neurons in the brain, including both descending and local interneurons, by recording them extracellularly using steel microelectrodes. For analyzing the synaptic mechanisms subserving the behavioral context-dependent activities of statocyst interneurons, a treadmill system was also developed to probe with a glass microelectrode the brain of an animal on the treadmill engaged in walking and abdominal posture movements. Although no statocyst interneurons has been analyzed yet presently, those interneurons have been identified that change spike or synaptic activities when the animal initiates walking or abdominal posture movements that are closely associate with the posture control mechanism. Less