| Parkinson's disease, well known for its disruptive effects on movement, also affects cognitive function and leads to a variety of learning and memory deficits. Currently, there is no clear understanding of the precise nature of these deficits, nor of their neural basis. The studies presented here examined learning and memory deficits in patients with Parkinson's disease, with two main goals. First, we sought to provide a more detailed understanding of the nature of learning and memory impairments in Parkinson's disease. To that end, the present studies developed tasks and analyses that assessed strategies involved in the learning process. These studies revealed that Parkinson's patients are specifically impaired at complex, integrative learning strategies, while simpler learning strategies remain intact. The second main goal of the present studies was to gain a better understanding of how the learning and memory impairments in Parkinson's disease relate to what is known of the underlying neuropathology of the disease. The primary pathology of Parkinson's disease is disrupted basal ganglia function, due cell death among dopamine neurons. Taking into account data from physiological and computational perspectives, we confirmed several predictions regarding the role of dopamine and the basal ganglia in particular types of learning and memory, such as incremental feedback-based learning and reward-related sequence learning. We further examined the effect of medication (dopamine precursors) on learning and memory in Parkinson's disease. We found that medication often does not alleviate learning deficits in Parkinson's disease, and in some cases may even lead to worse impairments. Overall, these studies provide a more accurate understanding of the cognitive deficits in Parkinson's disease, of how these deficits relate to the underlying neural pathology of the disease, and of the effect of medication on learning and memory in Parkinson's patients. |
