Figure 2.

MC-induced responses in GPe. A, B, Population PSTHs of two major response patterns obtained in control rats. In these and subsequent figures, population PSTH (i.e., average PSTH of multiple neurons) was constructed from 100 stimulation trials. The bin width of PSTHs is 1 ms unless otherwise noted, and MC stimulation was given at time = 0 (arrow). The response pattern, the number of neurons included in each population PSTH, and the average prestimulus firing frequency with 95% confidence interval (solid line and dashed lines) are shown in each figure. Ex., Excitation; Inh., inhibition. C, D, Population responses of two major response patterns obtained in 6-OHDA rats. Ex., Excitation; Inh., inhibition. E, Population PSTHs of all MC-responsive GPe neurons in control and 6-OHDA rats. The green PSTH shows the delta between the control and 6-OHDA PSTHs. F, A population PSTH of neurons that responded with an early excitation, a short inhibition, and a late excitation in 6-OHDA rats after injection of CPP, an NMDA antagonist, into the recording sites. For comparison, the same PSTH (in green) shown in C is scaled to have the same prestimulus firing rate and overlaid.