Julie Stout's Laboratory

Clinical & Cognitive Neuroscience Research

PD Study: Parkinson's Disease Study

Set-shifting processes in Parkinson's disease

The ability to flexibly alter our thoughts and actions is necessary to smoothly transition between the multitude of demands and environments that we encounter in our daily lives. Although everyone has difficulty with the ability to shift sets, some individuals find this process to be especially difficult. Individuals with Parkinson's disease (PD), a neurodegenerative disease resulting from the loss of dopamine neurons in the basal ganglia, have consistently shown impaired set-shifting (c.f. Owen et al., 1993). Currently, there are two competing accounts for the set-shifting deficit associated with PD, learned irrelevance and perseveration. According to the learned irrelevance hypothesis, impaired performance results from the inability to respond to previously irrelevant information; the perseveration hypothesis asserts that poor performance is due to continued responding to the previously relevant information (Gauntlett-Gilbert et al., 1999; Owen et al., 1993).

To determine which mechanism accounts for PD performance, we have developed a new task-switching measure, which will not only remove the confounds associated with previous set-shifting tasks, but will also isolate each mechanism. As part of this study, participants will complete the new task-switching measure, as well as measures of general cognitive functioning, motor symptoms, and behavioral/affective symptoms.