Fig. 1.

Nucleus accumbens medium spiny neurons exhibit a membrane potential with UP and DOWN states. A, A representative trace of a neuron with alternating DOWN (−72 mV;bottom arrowhead) and UP (−59 mV; top arrowhead) membrane potential states. B, Membrane potential distribution of the trace shown in Areveals two peaks that correspond to the UP and DOWN states. This histogram fits to a two-peak Gaussian distribution (black line; r² = 0.91).C, Neurobiotin staining revealed morphology typical of medium spiny neurons.