Bilateral 6-hydroxydopamine lesion in the dopaminergic A8 cell group produces long-lasting deficits in motor programming of cats

The effects of a small 6-hydroxydopamine lesion in the A8 cell group were studied in cats (N = 8) trained to walk on a treadmill. This setup allows the assessment of subtle changes in motor programming. The lesion produced long-lasting effects: (a) a decreased ability to switch arbitrarily motor patterns; (b) an increased ability to switch motor patterns with the help of stimuli provided by the apparatus; (c) alterations in the sequential patterning of motor behavior and in the kinetic melody of movements. It is suggested that the lesion produced a hypofunction of A9 cells that is compensated by a hyperfunction of A10 cells. It is concluded that subtle lesions in the A8 cell group produce long-lasting deficits in motor programming, implying that degeneration of this dopaminergic cell group may contribute to symptoms seen in Parkinson's disease.