Disruption of latent inhibition to a contextual stimulus with systemic amphetamine

This experiment examined the effects of 0.5 and 1.5 mg/kg doses of amphetamine (AMP) in male Wistar rats, on conditioning to a contextual stimulus that for half the animals has been pre-exposed, in an appetitive conditioning procedure. Amphetamine was administered during both pre-exposure (3 days) and acquisition (15 days). Latent inhibition (LI, reduced conditioning in pre-exposed relative to non-pre-exposed rats) was seen in controls but not at either AMP dose. This abolition of LI was seen under AMP at two levels of responding in acquisition and confirmed in drug free extinction. It suggests that, like conditioning to discrete stimuli, conditioning to contextual stimuli is subject to LI and can be disrupted by AMP.