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Electrophysiology, sensorimotor, crab, gastric mill, central pattern generator, behavior, video motion tracking


Central pattern generators (CPGs) generate rhythmic output patterns and drive vital behaviors such as breathing, swallowing, locomotion and chewing 1-10. While most insights into the rhythm generating mechanisms of CPGs have been derived from isolated nervous system preparations, the relationship between neural activity and corresponding behavioral expression is often unclear. The stomatogastric system of decapod crustaceans is one of the best characterized neural system for motor pattern generation 9-12 and many mechanisms of motor pattern generation and selection have been discovered in this system. Since most studies are limited to the isolated nervous system, little is known about the actual behavioral output of this system. For example, it is unknown whether the observed flexibility in the motor patterns is present in vivo and whether distinct motor activities drive corresponding behavioral patterns. We present a method which allows electrophysiological recordings of CPG neurons and the simultaneous monitoring of the behavioral output of the stomatogastric nervous system. For this, we use extracellular hook electrodes either for recording or stimulation of neurons in the gastric mill CPG that drive the chewing movements of three teeth in the foregut of the animal. Electrodes are applied in tethered, but otherwise fully intact crabs (Cancer pagurus) and an endoscope is used to monitor tooth movements. Nerve and video recordings of the endoscopic camera are synchronized and motion tracking techniques are used to analyze gastric mill movements. This approach thus allows testing the behavioral relevance of the neural activity patterns produced by central pattern generators.


The attached video describes the details of the protocol.