Fig. 4. Regulation of swimming by cell SIN1's firing frequency. A. Control. DP nerve stimulation elicits a swim episode 15 cycle in length. B. During th e next DP nerve induced swim episode, depolarization of cell SIN1 with a 1 sec current pulse rapidly hyperpolarizes cell 204 and terminates the swim episode. Note that depolarization of cell SIN1 causes a barrage of inhibitory postsynap tic potentials in cell 204. C. When the preparation is not swimming, strong excitation of cell SIN1 elicits only a slight inhibitory response in cell 204. Cell SIN1 was depolarized by intracellular injection of current. In A. timin g of the DP nerve stimulation is represented by a bar. Return to Results