Figure 1a’’’ shows that optical inhibition of eNpHR3.0-expressing PL reduced responding during cocaine-primed reinstatement (Friedman statistic = 11.19, P < 0.001, n = 7). Similarly, inhibition of the NAcore after intra-NAcore administration of either ArchT (n = 6) or eNpHR3.0 (n = 6) diminished responding during cocaine + cue-primed reinstatement sessions (Fig. 1b’’’). A Kruskal–Wallis test revealed no significant difference in responding between the ArchT or eNpHR3.0 animals, and thus, the data from these groups were pooled for analysis (Friedman statistic = 18.17, P < 0.001, n = 12). Figure 1c’’’ shows that optical inhibition of ArchT-expressing PL fibers in the NAcore reduced cocaine seeking induced by either a cocaine-priming injection (10 mg/kg; Friedman statistic = 9.80, P = 0.006, n = 10) or a combination cocaine-priming + cues (Friedman statistic = 9.90, P = 0.003, n = 10). In no experiment was inactive lever pressing affected by laser stimulation of fibers in the NAcore (data not shown).
