Implicit task switching in Parkinson’s disease is preserved when on medication

Abstract

People with Parkinson's disease have been shown to have difficulty switching between movement plans. In the great majority of studies, the need to switch between tasks was made explicitly. Here, we tested whether people with Parkinson's disease, taking their normal medication, have difficulty switching between implicitly specified tasks. We further examined whether this switch is performed predictively or reactively. Twenty five people with Parkinson's disease continuously increased or decreased the frequency of their arm movements, inducing an abrupt-but unaware-switch between rhythmic movements (at high frequencies) and discrete movements (at low frequencies). We tested whether that precipitous change was performed reactively or predictively. We found that 56% of participants predictively switched between the two movement types. The ability of people with Parkinson's disease, taking their regular medication, to predictively control their movements on implicit tasks is thus preserved.

The effects of an object’s height and weight on force calibration and kinematics when post-stroke and healthy individuals reach and grasp

“…This measure was not examined for force analysis in previous studies. However, number of peaks, as a measure of movement smoothness, is commonly used in movement-velocity and acceleration analysis 47,[60][61][62]80 . In the context of force regulation, this measure may reflect the efficiency of planning and execution of the grasp-and-lift movement.…”

“…Kinematic data analysis. Kinematic data were filtered using the Butterworth filter with a cutoff of 20Hz [60][61][62][63] , and then used to calculate the following kinematic outcome measures:…”