(A1 and B1) Examples of response types observed for 10 s stimulation of GPe or Str projections. (A2 and B2) Quantification types of SNr response to optogenetic stimulation at varying frequencies (GPe: animals, 12 slices, 10 Hz, 20 Hz, and 40 Hz = 40 cells, 60 Hz = 39 cells; Str: animals, 12 slices, 10 Hz, 20 Hz, and 40 Hz = 33 cells, 60 Hz = 31 cells). (A3 and B3) Effect of GPe or Str stimulation on the firing rate of SNr neurons averaged across all trials for stimulation at 40 Hz. Error bars indicate the standard deviation. The 10 s stimulation period was broken into 1 s intervals to show the gradual weakening of inhibition during stimulation.