Fig. 6. Effects of intra-NAc BDNF infusions on locomotor activation after 10 mg/kg cocaine. BDNF-infused animals showed higher activity rates than vehicle-infused animals after repeated cocaine injections (days 7–9). By day 10, the vehicle-infused animals were similar to BDNF-infused animals because they had become sensitized to this moderate dose of cocaine. No further differences between the groups were observed over subsequent days, except on day 13 when vehicle-infused animals showed lower activity rates (see Results). Significant differences (*p < 0.05) at time points after cocaine injections were as follows: day 7 at 10, 20, and 50 min, F(1,6) = 15.35, 120.81, and 6.35, respectively; day 8 at 10, 20, 50, and 60 min,F(1,6) = 6.03, 7.41, 6.11, and 6.47, respectively; day 9 at 10, 30, 40, and 50 min,F(1,6) = 6.19, 6.67, 6.40, and 6.66, respectively; day 13 at 10, 20, and 50 minF(1,6) = 11.35, 5.82, and 6.24, respectively. No differences between the groups were found before the cocaine injections. Data are expressed as the mean ± SEM number of photocell disruptions over the 30 min test period.