Figure 9.

Electrical stimulation of a descending unit associated with spontaneous termination of walking behavior. A, Spike activity of the descending unit recorded when the animal initiated walking in response to mechanical stimulation of the telson and terminated spontaneously. The unit activity (top trace, arrowhead) increased before the decrease of leg muscle activity (second trace). B, Activity profiles of the termination unit compiled from three bouts of walking. C, Behavioral effects is caused the electrical stimulation of the bundle containing the termination unit during walking. Electrical stimulation (200 pulses of 0.2 ms duration at 50 Hz, 31 μA shown in solid horizontal bar at top) was applied to the bundle at 10 different timings during walking behavior. At the bottom are superimposed smoothed EMGs, indicating a decrease in the leg muscle activity after the electrical stimulation (shown by the gray area).