(A) Time-course plot showing the peak amplitude response of optically evoked inhibitory postsynaptic current (oIPSCs) while applying 50 µM picrotoxin (PTX) to the recording solution (N=2); representative traces of oIPSCs at three timepoints of the recording (pre-drug, 10 min after PTX, and 15 min after PTX). (B) Time-course plot showing the peak amplitude response of oIPSCs while applying 1 µM of reserpine, a VMAT2 inhibitor, followed by 50 µM PTX to the recording solution; representative traces of oIPSCs at three timepoints of the recording (pre-drug, response in reserpine prior to PTX, and response to reserpine and PTX). (C–D) Summary graphs of oIPSC response delay (C) and rise time (D) recorded in ventral striatal medium spiny neurons (MSNs). (E–F) Summary graphs of oIPSC response delay (E) and rise time (F) in dorsal striatal MSNs.