SOCIAL-ISOLATION IN THE RAT PRODUCES DEVELOPMENTALLY SPECIFIC DEFICITS IN PREPULSE INHIBITION OF THE ACOUSTIC STARTLE RESPONSE WITHOUT DISRUPTING LATENT INHIBITION

A series of experiments examined the effects of 8 weeks of social isol ation on spontaneous locomotor activity, prepulse inhibition (PPI) of the acoustic startle response, latent inhibition (LI) in a conditioned suppression paradigm, and basal and d-amphetamine stimulated dopamine (DA) release in the ventral striatum, as measured by in vivo microdia lysis. Both isolation-reared animals (those isolated from the weaning age) and isolation-housed animals (those isolated as adults) were hype ractive when placed in a novel environment. Social isolation also led to deficits in PPI of the acoustic startle response that were specific to isolation-reared animals. Isolation rearing was without effect on the expression of LI but did lead to an enhanced response to systemic d-amphetamine in terms of striatal DA release. The data are discussed with respect to the involvement of ventral striatal DA mechanisms in t he expression of PPI and LI, differences in the impact of social isola tion in young and adult animals, and the utility of social isolation m odel as a nonlesion, nonpharmacologic means of perturbing ventral stri atal DA function.