Limb use and complex ultrasonic vocalization in a rat model of Parkinson's disease: deficit-targeted training.

Recent evidence in animal models of Parkinson's disease (PD) suggests that exercise and other forms of motor enhancement can be beneficial when applied during the degeneration of dopamine neurons. Behaviours that depend on adequate levels of striatal dopamine may provide particularly favourable targets for therapeutic motor interventions. Task-specific motor enrichment procedures have been used to improve functional and neural outcomes following unilateral infusions of 6-hydroxydopamine (6-OHDA) into the nigrostriatal pathway in rats. In contrast, forced non-use procedures can exaggerate the degree of degeneration. Limb-use akinesia and ultrasonic vocalization in the 50-kHz range may be useful behavioural indices of nigrostriatal integrity and may model common deficits found in PD. These deficits in movement initiation and fine sensorimotor control are potential targets for early training interventions.