All behavior experiments were conducted in the light phase from 1100–1500. Animals were brought into the testing room at least 30min prior to the start of behavioral experiments, then placed individually into locomotor activity chambers (Med Associates, St Albans, VT) for 30 min or 1 hr, as indicated. Total distance traveled was recorded in 5 min bins. Zone analysis was conducted to determine time spent in center, defined as area of open field excluding peripheral 5 inches on each side of 16×16” square. For cocaine-induced locomotor activity, 24 hours following open field test (day 0), animals were placed in activity chamber for 30 minutes, then received saline (0.9%) solution i.p. and were immediately returned to activity chamber for 30 minutes for 2 consecutive days (days 1–2). On day 3, animals received 20mg/kg cocaine hydrochloride (Sigma-Aldrich) dissociated in saline (0.9%) solution i.p. and were immediately placed in activity chambers for 30 minutes. For virus-injected animals, animals underwent behavioral testing 14–20 days post virus injection. For behavioral experiments, 24–72 hours after the last cocaine injection, brain sections were taken for confirmation of virus expression in VTA.
