Repeated cocaine administration reduces action potential amplitudes of NAc neurons. Representative traces showing action potentials recorded from NAc neurons in saline-pretreated and cocaine-pretreated rats on the third day of withdrawal. Note the reduced amplitude of the action potential in the cocaine-pretreated neuron. The traces are normalized for action potential thresholds, which were −40.2 mV in the control neuron and −45.0 mV in the cocaine neuron. Resting membrane potentials were −79 mV for control and −86 mV for cocaine. Action potentials were evoked with intracellular depolarizing current injection (0.7 and 0.9 nA for saline and cocaine, respectively).