The effects of phencyclidine on latent inhibition in taste aversion conditioning: differential effects of preexposure and conditioning

Latent inhibition (LI) is a behavioural procedure in which preexposure to a stimulus not followed by reinforcement retards subsequent conditioning to this stimulus when it is paired with reinforcement. Changes in LI thus reflect greater or lesser retardation of learning which essentially implies a potentiation or an attenuation of the LI effect. LI has proved sensitive to psychotomimetic and antipsychotic treatment, which has encouraged its use to model learning and attention deficits in schizophrenia. In the present study, experiments were conducted to evaluate the effects of the psychotomimetic drug, phencyclidine (PCP, 2 mg/kg), and compare it with d-amphetamine (d-AMP, 0.33 and 1 mg/kg), on LI using a conditioned taste aversion procedure. PCP was found to potentiate LI when administered acutely prior to the conditioning trails, while no such effect was observed when administered prior to the preexposure trials. d-AMP, on the other hand, disrupted LI possibly due to a failure to induce a persistent taste aversion conditioning.