Impairment of hand dexterity in Parkinson's disease (PD) is usually attributed to bradykinesia. Recently, behavioral studies illustrated that decreased dexterity might also be due to limb-kinetic apraxia (LkA), as demonstrated by impaired performance in a coin rotation task. Here, we provide a first investigation on whether functional magnetic resonance imaging (fMRI) may reveal specific brain activation patterns for PD patients with impaired performance in a coin rotation task. We compared coin rotation as an apraxia task to simple finger tapping as a bradykinesia task in ten PD patients OFF medication and matched healthy controls. In addition to a tendency for general overactivation, PD patients showed a perirolandic dissociation with precentral overactivation and postcentral underactivation. This finding significantly separated PD patients from healthy controls.
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