Transient K⁺ current,I_A, in PD neurons was larger in decentralized preparations (B, C) than in control (A). B and C are from separate decentralized preparations to illustrate variability in recorded time constants. I_A was isolated by pharmacological blockade and digital subtraction (see Materials and Methods). Holding potential, −50 mV. A1, B1, C1,Steady-state activation: current responses to voltage steps (500 msec) between −70 and +50 mV in 10 mV increments. A2, B2, C2,Steady-state inactivation: currents recorded in response to a test pulse (+50 mV, 400 msec) from prepulses ranging from −120 to −20 mV in 5 mV increments.