Melbourne School of Psychological Sciences - Theses
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ItemTask switching in people with Parkinson's disease: the role of the basal ganglia( 2012)This thesis examines the ability to switch attention between two tasks. People with Parkinson’s disease (PwP) are slower and/or make more errors when required to switch their attention between performing two different but conceptually similar tasks (R. Cools et al. 2001a). However, the exact cause of this impairment is debated, and although many authors attribute dysfunction to executive control, it may be that the basal ganglia (BG) impairment in Parkinson’s disease (PD) results in reduced ability to provide inhibitory cognitive control. In this thesis I conducted a series of experiments to investigate the task switching deficit in PwP. I first describe the theory that the BG contribute to cognition by allowing flexible switching between cognitive strategies, depending on the environmental demands. I then provide evidence to suggest that the net increase in the overall level of neural inhibition within the BG is causing this process to become inflexible. I argue that PwP experience a deficit in inhibitory cognitive control. Using a combination of the task switching and go/nogo paradigms, I present five studies that were designed to investigate the nature of the task switching deficit in PwP. First, two studies investigated the relationship between stimuli and responses in the task switching paradigm. Next, study 3 looked at the contribution of cue priming to the task switching deficit in PwP. The two final studies aimed to investigate the role of task inhibition. In summary, I argue that an increase in neural inhibition in the BG of PwP results in difficulty inhibiting, and thus switching between, complex stimulus-response associations.