Role of the nucleus accumbens in social memory in rats

Recognition of a juvenile conspecific by an adult male rat is known to be reflected by reduced anogenital investigation (A.G.I.) of this young individual by the adult, when the two animals are reexposed to each other after some short delay. As the delay is increased, the reduction in A.G.I. is reduced. This measure of social memory can be modulated by several drugs, among others cholinomimetic agents. In this study, the effects of direct manipulation of the nucleus accumbens were studied. Local administration of (3,4-dihydroxyphenylimino)-2-imidazoline (DPI: 0.1-1.5 micrograms) decreased investigatory behaviour at the second exposure after a long interexposure-interval, while ergometrine (0.1 micrograms) counteracted this reduction by DPI. These findings suggest a role for the nucleus accumbens in social recognition, in particular for the so-called DAi receptors which are stimulated and inhibited by DPI and ergometrine respectively.