Cortical activity in Parkinson's disease during executive processing depends on striatal involvement
Oury Monchi1, Michael Petrides, Beatriz Mejia-Constain
1Functional Neuroimaging Unit, Research Centre, Institut Universitaire de Gériatrie de Montréal, Montreal, Quebec, Canada. oury.monchi@umontreal.ca
Brain : a Journal of Neurology
|November 24, 2006
Summary
Early Parkinson's disease patients show altered brain activity during executive tasks. Functional magnetic resonance imaging (fMRI) reveals unusual cortical activation patterns, challenging traditional models of cognitive decline.
Area of Science:
- Neuroscience
- Cognitive Neurology
- Neuroimaging
Background:
- Idiopathic Parkinson's disease (PD) is associated with executive function deficits, including planning and set-shifting, even in early stages.
- The caudate nucleus's role in executive processes, particularly set-shifting, has been investigated using novel tasks and functional magnetic resonance imaging (fMRI).
Purpose of the Study:
- To compare brain activation patterns in early-stage Parkinson's disease patients and matched controls using a card-sorting task.
- To investigate the specific involvement of the caudate nucleus in executive functions within the context of Parkinson's disease.
Main Methods:
- Utilized a functional magnetic resonance imaging (fMRI) protocol with a card-sorting task designed to study executive processes.
- Compared event-related fMRI activation patterns between seven early-stage Parkinson's disease patients (Hoehn and Yahr stages 1-2) and age- and sex-matched healthy controls.
Main Results:
- Parkinson's disease patients exhibited increased cortical activation in conditions not requiring the caudate nucleus, compared to controls.
- Patients showed decreased cortical activation in conditions significantly involving the caudate nucleus.
- Observed activation patterns extended to prefrontal, parietal, and prestriate cortical areas.
Conclusions:
- The findings suggest a complex pattern of altered cortical activation in Parkinson's disease, characterized by both reduced and increased activity depending on task demands and caudate nucleus involvement.
- These results challenge the traditional view of solely decreased cortical activity due to nigrostriatal dopamine depletion.
- The study supports the hypothesis that both nigrostriatal and mesocortical dopaminergic pathways contribute to cognitive deficits in Parkinson's disease.
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