Fig. 5.

Higher transient Na_V current (I_NaT) density in SNr GABA neurons than in nigral DA neurons. I_NaT was evoked from a holding potential of −100 mV by a test potential ranging from −80 mV to +30 mV in 5-mV steps. I_NaT started to appear at −55 mV. For example current traces, see Fig. 6A, because Figs. 5 and 6A were derived from the same data set. The reversal potential was obtained by linear-fitting the data points between 0 mV and 30 mV (dotted lines), according to the method of Safronov and Vogel (1995) and Raman et al. (2000). The estimated reversal potential was 49.8 mV for GABA neurons and 49.9 mV for DA neurons.