Figure 3.

The effect of acute Meth challenge injection (0.5 mg/kg, i.p.) on up and down states in accumbens neurons depends on the behavioral response to repeated Meth administration. a, Traces of a representative neuron from a behaviorally sensitized animal, before and 19 min after acute Meth administration. No changes in up- and down-state parameters were observed in the three of four cells (all in the accumbens core) that exhibited this type of response. b, Representative neuron from a nonsensitized animal, before and 18 min after Meth injection. Note the loss of up and down states. This transition to a steady depolarized state was observed in five of five cells tested (3 in core, 1 in shell, 1 in rostral pole of the accumbens). c, Representative neuron from a saline-treated animal, before and 17 min after administration of Meth challenge. Up and down states were abolished in three (2 core; 1 shell) of four cells tested (the fourth cell was in the core).