Behavioral effects of psychomotor stimulant infusions into amygdaloid nuclei

The role of amygdaloid nuclei in locomotion, stereotypy, and conditioned place preference (CPP) produced by psychomotor stimulants was examined. Five 2-day conditioning trials were conducted over 10 consecutive days. Rats received bilateral intracranial infusions of saline, cocaine (25-100 micrograms/side), or amphetamine (0.31-20 micrograms/side) into the ventricles (ICV), basolateral amygdala (BlA), or central amygdala (CeA) and were confined to a compartment. On alternating days, rats received sham infusions and were confined to a different compartment. Locomotion was measured daily, stereotypy was measured on trials 1 and 5, and CPP was measured 24 h after conditioning. ICV infusions of cocaine or amphetamine produced locomotion, rearing, and CPP. Intra-BlA and intra-CeA infusions of the highest dose of cocaine produced locomotion. In contrast, intra-CeA infusions of amphetamine potently produced locomotion and CPP. Intra-BlA infusions of amphetamine, however, did not produce any behavioral changes. These results suggest that the CeA, but not the BlA, is involved in initiating reward and locomotion produced by amphetamine.