Behavioral effects of psychomotor stimulants in rats with dorsal or ventral subiculum lesions: Locomotion, cocaine self-administration, and prepulse inhibition of startle

Compelling evidence suggests a primary role for the mesoaccumbens dopaminer gic pathway in the behavioral effects of amphetamine and cocaine. but the r oles of other projections to the accumbens, including those arising in the hippocampal formation, are less clear. The authors evaluated the effects of discrete excitotoxic lesions of either the dorsal or ventral subiculum on the locomotor activating. reinforcing, and sensorimotor gating-disruptive e ffects of psychomotor stimulant drugs. Whereas dorsal subiculum-lesioned ra ts were hyperactive in tests of exploratory locomotion and startle reactivi ty. ventral subiculum-lesioned rats exhibited an attenuated locomotor respo nse to amphetamine, moderately impaired acquisition of cocaine self-adminis tration, and reduced levels of prepulse inhibition of startle. These 2 beha vioral profiles overlap considerably with those previously observed in rats with lesions of the rostrodorsal and caudomedial accumbens, respectively, and suggest that projections from dorsal subiculum to accumbens core and ve ntral subiculum to accumbens shell exert distinct influences on behavioral responses that are amplified by psychomotor stimulant drugs.