“…For example, the capacity of apomorphine to in duce aggressive behavior in nonmanipulated ani mals (13,20,21) is greatly potentiated during withdrawal from chronic haloperidol (9) and morphine (10,15) administration. Several as pects of the stereotyped behavior induced by apomorphine are also enhanced by previous manipulations of animals, such as pretreatment with catecholamine-depleting drugs (8,25), withdrawal from previous neuroleptic treat ment (18,19,22), and lesions of nigrostriatal pathway (7,12).…”