Fig. 4.

Effects of cocaine reward trials on DMS task performance and PFC activity as a function of cognitive load. a Dose effect of cocaine reward infusion (0.03–0.09 mg/kg/inf) on mean DMS performance as a function of increased number of Match phase images in sessions with both cocaine (40%) and juice (60%) reward trials. Asterisks indicate significant differences (*p<0.01, **p<0.001) from Control (juice reward) sessions. b ^[18]FDG PET scan difference image between juice only and Mixed trial cocaine+juice reward sessions showing increased activation of dlPFC during cocaine + juice reward sessions (Cocaine > Juice) compared to sessions with only juice reward trials. Color bar at right indicates degree of significance with respect to t values as in Fig. 1a. c Mean PEHs of PFC neuron firing rates in Match phase on low vs. high cognitive load cocaine reward trials from the same sessions as in a (summed across all dose levels) plotted with superimposed Match R latencies (red and green bars) on the same trials (see Fig. 3c). Presentation of Match phase images at t=0.0 s (dotted line). Superimposed bars (green, low load; red, high load) indicate normalized frequency distributions of Match R latencies on the same cocaine rewarded trials. Asterisks and horizontal bars indicate time bins rates that differ significantly (*p<0.01, **p<0.001) from pre-Match phase baseline (−2.0 to 0.0 s)