The 'supersensitive' locomotor response to apomorphine resulting from 6-hydroxydopamine (6-OHDA)-induced denervation of the nucleus accumbens (N.Acc.) was studied in animals following selective damage to cell bodies within the substantia innominata (SI) and lateral preoptic region (LPO). Ibotenic acid-induced lesions of the SI and LPO dramatically attenuated the locomotor response to apomorphine in 6-OHDA-infused animals. Thus, the locomotor response that follows dopaminergic stimulation within the N.Acc. depends to a great degree on the integrity of cells within the SI and LPO region.