HemiParkinson analogue rats display active support in good limbs versus passive support in bad limbs on a skilled reaching task of variable height.

Rats with unilateral dopamine (DA) depletion (hemiParkinson analogue rats) are impaired in using the contralateral (bad) limbs for skilled movements and for postural adjustments and compensate by using their good limbs in novel ways. The present study consisted of a reaching task in which compensatory adjustments using the good limbs would not be affective, thus forcing the rats to use their bad limbs. The DA-depleted rats failed to use their bad hindlimb to extend their reach at high reaching heights and failed to lower their body with their bad forelimb to reach at low reaching heights. It is suggested that extensive DA depletion may result in the loss of the ability to apply forces with the affected limbs.