Fig. 6. Excitatory synaptic output from sint1 to synergistic motoneurons. The dorsal aspect of the right half of the CNS, including the right pleural and pedal ganglia, is shown diagrammatically (rostral direction upward). The diagram also shows the relative positions of the soma of Rsint1 in the pleural ganglion and of eight individual motoneurons in the ipsilateral pedal ganglion that are known to participate in swimming behavior. Single spikes were driven in Rsint1 at a rate of one per second in a quiescent whole animal preparation while recording membrane voltage at higher gain in the motoneurons. The results from 5–10 repetitions are superimposed. In each case the spike in Rsint1 elicits an epsp in the motoneuron. The time calibration bar (near A) corresponds to 40 ms (A–C,G) and 20 ms (D–F,H). For the postsynaptic potentials, the vertical calibration corresponds to 2 mV (A,B), 4 mV (F–H), and 20 mV in the other recordings. The epsps in A and B occur with latencies of 20–40 ms, while those in C–H occur with latencies of 2–5 ms. These results are characteristic of those obtained in 30 separate whole animal preparations involving >150 paired recordings.