Fig. 1.
Purkinje cell depolarization induces a biphasic inward current with fast and slow components. (a) A train of depolarizing command pulses from −70 to 0 mV was given, as illustrated in Inset. This train consisted of five pulses, each 10 msec long, with an interpulse interval of 100 msec. (Inset calibration bars: 2 nA, 50 msec.) This induced a biphasic inward current with fast (open circle) and slow (filled circle) components. (b) Depolarizing command pulses were given from different holding voltages, and the resultant inward currents were measured. The slow component was marked with filled circles. In these recordings, 20 μM NBQX was added, and a GABAA receptor antagonist was omitted to allow for simultaneous recording of spontaneous IPSCs and comparison of their reversal with that of both components of the biphasic inward current. Lower traces are expanded from the squares. ECl was calculated to be −66.2 mV. (Calibration bars: 200 pA, 2 sec.) (c) We call the slow component of this response “depolarization induced slow current” (DISC). In this graph, DISC charge transfer was measured, and the mean ± SE was plotted as a function of time (n = 5).