Fig. 5. Effect of dnqx on indirect excitation of cell 204 by p cell. Control: In normal physiological saline, P cell stimulation (+1.7 nA, 2 s, 20 Hz) results in excitation of cell 204 and in swimming. DNQX: After the nerve cord is bathed in saline containing 100 mM DNQX, cell 204 no longer responds to P cell stimulation. Wash: When the nerve cord is returned to normal physiological saline, sustained excitation of cell 204 following P cell stimulation returns. Stimulus artifacts were removed from the cell 204 DNQX trace for clarity. The tops of P cell action potentials may have been clipped. CALIBRATION: 5 mV [cell 204] and 50 mV [P cell], 2 s.