DISRUPTION OF THE KAMIN BLOCKING EFFECT IN SCHIZOPHRENIA AND IN NORMAL SUBJECTS FOLLOWING AMPHETAMINE

The Kamin blocking effect (KBE) is an established animal learning para digm measuring selective processing, in which reduced blocking reflect s allocation of greater processing resources to non-relevant informati on. Two KBE tasks are described below. Results from studies using the first (between-subjects) task indicate that KBE is abolished in acute schizophrenics with positive psychotic symptoms. It is also abolished in the relatives of schizophrenic subjects, although interpretation of this finding is hampered by poor performance of subjects in the contr ol condition. The second (within-subjects) task indicated abolition of KBE in schizophrenic patients with positive psychotic symptoms. Admin istration of acute amphetamine to normal human subjects did not signif icantly disrupt performance on the first task. Whilst for the second t ask, although blocking was limited to placebo subjects, overall pre-ex posure effects are not sufficiently strong to indicate specific drug e ffects. (C) 1997 Elsevier Science B.V.