Final Report Summary - NEUROKINEMATICS (Neuronal Dynamics of the Basal Ganglia and the Kinematics of Motor Habits)
The main objective of the project was to further the understanding of the neural mechanisms responsible for the generation of motor habits. The project’s working hypothesis, based on preliminary data and previous studies, was that the striatum, a brain region which dysfunctions in Parkinson's disease, becomes increasingly responsible for the moment-to-moment execution of actions, as they gradually become habitual. The results we obtained during the project completely challenged this hypothesis. They indicate that the striatum is not required to initiate or execute motor habits but determines the animals' sensitivity to effort. For instance, lesions of the striatum rendered the animals more sensitive to effort and consequently, they adapted to this perturbation by performing slower movements (slow movements require less effort than fast movements). Importantly such lesion did not change the motivation of the animals for rewards and did not affect their ability to perform movements at different speeds. We also found preliminary evidence that the activity of the two main types of striatal neurons bidirectionally modulates effort sensitivity. Overall, our results suggest that the classical view of the striatum as a controller of action execution must be revised.