Fig. 2.

Carbachol excited the swimmeret system in a dose-dependent manner. A, Recordings of PS bursts from one preparation exposed to three concentrations of carbachol.B, The frequency of PS bursts increased as the concentration of carbachol increased. The solid circlesand error bars mark frequencies (mean ± SD) of PS bursts in preparations bathed in the given concentrations of carbachol (n = 3 preparations); the diamondmarks frequencies (mean ± SD) of PS bursts expressed spontaneously in saline (n = 3 preparations).C, The structures of the motor patterns produced spontaneously by each ganglion were similar to those produced when the system was excited by carbachol. The periods, durations, and latencies of the spontaneous patterns were normalized to the mean period of the carbachol-induced patterns. Shaded solid boxes show bursts recorded in carbachol; open dotted boxes show normalized spontaneous bursts. Each box shows the mean duration (+SD) of bursts in the named motor axons. The secondPSE5 and PSE3 box begins at the mean period (−SD) of the pattern. Each RSE5 and RSE3 box begins at the mean latency (−SD) of those bursts after the PSE burst, and so illustrates the mean phase difference between PSE and RSE activity to the swimmeret.