Electronic Thesis and Dissertation Repository


Master of Science




Dr. Penny MacDonald and Dr. Adrian Owen


Cognitive impairment is recognized in Parkinson’s disease (PD). Understanding striatum-mediated cognitive functions will help elucidate some of these abnormalities. Learning is often impaired by dopaminergic medication. However, dorsal striatum (DS) has been implicated in learning; an unexpected result given that dopaminergic therapy, the gold standard treatment for PD, remediates DS functioning. In two separate experiments, stimulus-response association learning and decision-making were examined in healthy individuals using functional magnetic resonance imaging (fMRI), and in PD patients using behavioural methods. In Experiment 1, healthy individuals completed a stimulus-response learning task, and brain regions associated with learning versus decision-making were investigated using fMRI. In Experiment 2, patients with PD completed a similar task on and off their dopaminergic medication. Results from both experiments suggest that DS mediates decision-making and not learning. This greater understanding of striatum-mediated cognition will ultimately prompt clinicians to devise medication strategies that consider both motor and cognitive symptoms of PD.