EFFECTS OF ACUTE ADMINISTRATION OF D-AMPHETAMINE AND HALOPERIDOL ON PROCEDURAL LEARNING IN MAN

The effects of an indirect dopamine-agonist, d-amphetamine, and a non- selective dopamine receptor antagonist, haloperidol, were investigated in normal male volunteers using a between-subjects double-blind desig n in a procedural learning task, thought mainly to involve unconscious /automatic learning. The results showed: (1) d-amphetamine facilitated response speed, whereas haloperidol inhibited it, in comparison to pl acebo; (2) the linear increase in procedural learning corresponded wit h pharmacological manipulation of degree of dopaminergic activity, i.e . subjects given haloperidol showed the least, and subjects given d-am phetamine the greatest, procedural learning. The implications of these findings are discussed in relation to investigation of abnormalities of procedural learning processes in schizophrenia.