Figure 1.

(a) Experimental protocol for METH and saline treatments. (b) Effects of different doses of METH on stereotypic behavior scores of behavioral sensitization in tree shrews on the last day (d12) of the development period of behavioral sensitization and (c) the expression period of behavioral sensitization (d17). *p < .05, **p < .01, and ***p < .001 compared to the control group. ^## p < .01 compared to METH (1 mg/kg). ^$ p < .05 compared to METH (2 mg/kg). Data were presented as mean ± SEM. N = 10 per group