The contribution of neuroimaging for the study of cognitive deficits in Parkinson's disease.

The last few years have seen an increase in the number of studies using functional Magnetic Resonance Imaging (fMRI) along with receptor imaging and regional cerebral blood flow Positron Emission Tomography (PET) to understand the neurobiological underpinnings of cognitive deficits in Parkinson's disease (PD). These studies have shown evidence that the nigrostriatal degeneration solely cannot account for these deficits and that involvement of other neural systems such as the mesocortical dopamine may also play an important role. In this article, we provide a review of neuroimaging results regarding the role of possible compensatory activity, L-Dopa medication, and difference in genotypes on the cognitive deficits observed in PD. Finally, some future avenues for research are proposed.