Fig. 2.

Confirmation of visual identification of striatal neurons by electrophysiological properties, biocytin staining, and immunocytochemistry. A, Membrane potential changes in response to injection of 0.5 sec hyperpolarizing and depolarizing current pulses. Whole-cell current-clamp recording. Top traces are from a medium-sized striatal principal neuron, andbottom traces are from a large striatal interneuron. Currents injected were −50/130 and −60/120 pA, respectively. The resting potentials of the two cells were −71 and −64 mV; the membrane potentials were set to −70 mV (dashed lines) by injection of a small constant current. Note the marked afterhyperpolarization that follows each single action potential in the striatal interneuron. B, Camera lucida drawing of a large striatal interneuron filled with biocytin. The soma and the dendrites of the cell are drawn in black; the axonal arborization is drawn in red. The arrowpoints to the axon close to its origin at one of the primary dendrites. The filled circle in the inset indicates the location of the soma of the filled neuron (Str, striatum; LV, lateral ventricle; Cor, neocortex; D, dorsal; L, lateral).C, Fluorescence microphotographs of a large striatal interneuron filled intracellularly with biocytin and double-labeled with rhodamine-conjugated avidin (left, epi-illumination, 510–560 nm) and rat monoclonal antibody against ChAT/FITC-conjugated goat anti-rat antibody (right, epi-illumination, 450–490 nm).