Previous work in our lab has shown that rats with severe unilateral dopamine (DA) depletion show extreme preferential use of the impaired forelimb, but benefit from immobilization of the affected forelimb during or soon after degeneration (Tillerson et al. SFN Abst., 1999 ). We have extended those initial observations. Animals received 10 µg of the selective neurotoxin 6-hydroxydopamine (6-OHDA) into the MFB. Such lesions typically cause a 60-90% loss of DA in the striatum. By immobilizing the non-impaired forelimb immediately after the lesion, animals were forced to rely on their impaired limb for 7 days. When the casts were removed, the animals displayed no detectable impairment or asymmetry of limb use and showed no contralateral turning to apomorphine. In addition, these animals show remarkable sparing of striatal DA, its metabolites, and the vesicular monoamine transporter, suggesting a decrease in the extent of DA neuron degeneration. Whereas behavioral and neurochemical recovery appeared to be compl...