Changes in the response to amphetamine before and after MPTP treatment. Shown are an animal before MPTP treatment (a) and 4 months after cessation of MPTP treatment (b) in which some signal change is noted in the accumbens. The time course of rCBV changes in putamen in this representative study is shown before and after MPTP (c). The average changes in the regional rCBV measurements before and after MPTP are shown in parkinsonian primates (d). *p< 0.05; **p <0.01; ***p<0.005. Insular Cx, Insular cortex; PRG Cx, PRG cortex; SN, substantia nigra; RN/VTA, red nuclei/ventral tegmental area; PF Thal, parafascicular thalamus.