Feedback-based versus observational classification learning in healthy aging and Parkinson's disease.

Previous studies underline the role of dopamine in cognitive reinforcement learning. This has been demonstrated by a striatal involvement in feedback-based probabilistic classification learning. In order to determine to which extent the dopaminergic loss of Parkinson's disease and aging affects the feedback aspect in classification learning, we applied two versions of the same visual classification task.

The impact of normal aging and Parkinson's disease on response preparation in task-switching behavior.

This study investigates the ability to use foreknowledge in preparation of cognitive processes in young and older participants and in PD patients. Additionally, we test the hypothesis that age-associated cognitive deficits in task switching reflect a dopaminergic dysfunction that accompanies healthy aging. To this end, we use a task-switching paradigm that (i) is known to be highly sensitive for dopaminergic dysfunction in the frontostriatal loops and (ii) can be applied with predictable and unpredictable switch and non-switch trials to assess the effect of task foreknowledge.

Patients with Parkinson's disease learn to control complex systems-an indication for intact implicit cognitive skill learning.

Implicit memory and learning mechanisms are composed of multiple processes and systems. Previous studies demonstrated a basal ganglia involvement in purely cognitive tasks that form stimulus response habits by reinforcement learning such as implicit classification learning. We will test the basal ganglia influence on two cognitive implicit tasks previously described by Berry and Broadbent, the sugar production task and the personal interaction task.