Fig. 4.

A single cocaine or glutamate exposure produced behavioral sensitization after 2 and 6 days of drug abstinence. 4A) Planarians treated with 0.1 mM cocaine or water once on day 1 were exposed to 0.1 mM cocaine 2 or 6 days later. Data are expressed as mean activity counts ± S.E.M. during 1 min of cocaine exposure following 2 or 6 days of abstinence. **p < 0.01 or ***p < 0.001 compared to respective water/cocaine group. N = 8 planarians per group. 4B) Planarians treated with 0.1 mM glutamate or water once on day 1 were exposed to 0.1 mM glutamate 2 or 6 days later. Data are expressed as mean activity counts ± S.E.M. during 1 min of glutamate exposure following 2 or 6 days of abstinence. ***p < 0.001 compared to respective water/glutamate group. N = 8 planarians per group.