Figure 4: Specific blockers reveal the presence of presynaptic 1 family potassium channels at corticostriatal synapses. Representative experiments showing the reduction of PPR after exposure to (a) agitoxin-1 and (b) margatoxin. In both cases, the upper left panels show the time course of PPR as it changes due to drug administration. Horizontal bars indicate time of drug perfusion. Representative traces showing population spikes before (1) and after (2) exposure to drugs are shown in the right panel. The changes in (red) or (black) amplitude are shown on the left lower panels. Initially PPR was adjusted to obtain PPR ≥ 1. Addition of 1 specific blockers results in reduction of PPR that was associated with differential effects on or amplitudes.