Tonic NAc firing rates do not correlate with psychomotor activation. A, Representative horizontal brain slice showing placement of an electrode tip. B, Methamphetamine induces a bimodal response distribution (E neurons, firing rate >125% baseline, or firing rate >100% baseline and firing rate variability >125% baseline; I neurons, firing rate <75% baseline, or firing rate <100% baseline and firing rate variability <75% baseline). Unresponsive neurons (firing rate between 75% and 125% and firing rate variability between 75% and 125% baseline) are plotted in gray. C, Representative firing rate histograms of example E and I neurons in vehicle- and rimonabant-treated subjects (10 s bins). Arrows indicate time of vehicle/rimonabant (0.3 mg/kg; i.v.), saline, and methamphetamine (0.01, 0.1, 1, 3 mg/kg; i.v.) administration. D, Mean E neuron firing rates across time (60 s bins; top). Methamphetamine increases E neuron firing rates. Mean time spent in locomotion across time (60 s bins; bottom). E, Mean I neuron firing rates across time (60 s bins; top). Methamphetamine decreases I neuron firing rates. Rimonabant attenuates this effect. Mean time spent in stereotypy across time (60 s bins; bottom). Methamphetamine increases stereotypy. Rimonabant attenuates this effect. F, Linear regression of E neuron firing rates as a function of locomotion (60 s bins). G, Linear regression of I neuron firing rates as a function of stereotypy (60 s bins).