The excitation of GPi neurons induced by orexin-A is a direct postsynaptic effect. A In current-clamp recordings, TTX, together with NBQX, AP5, and SR95531, did not block the depolarization induced by orexin-A. B In voltage-clamp recordings, TTX, NBQX, AP5, and SR95531 did not block the inward current induced by orexin-A. C Group data from tested neurons (n = 5; n.s. not significant).