Electrophysiological phenotype of (wv/wv) dopaminergic SN neurons. A,B, Standard whole-cell current-clamp recordings of spontaneous electrical activity in dopaminergic SN neurons of wild-type (+/+) and homozygotic weaver (wv/wv) mouse.C, D, Responses of membrane potential to injection of hyperpolarizing currents of increasing amplitudes from −25 to −150 pA in steps of 25 pA in (+/+) and (wv/wv) dopaminergic SN neurons. E, F, Current response to voltage ramps from −120 to −40 mV from a holding potential of −60 mV in (+/+) and (wv/wv) dopaminergic SN neurons.Dotted lines indicate zero levels.