Bradykinesia has been associated with beta and gamma band interactions in the basal
ganglia-thalamo-cortical circuit in Parkinson's disease. In this present cross-sectional
study, we aimed to search for neural networks with electroencephalography whose frequency-specific
actions may predict bradykinesia.Twenty Parkinsonian patients treated with bilateral
subthalamic stimulation were first prescreened while we selected four levels of contralateral
stimulation (0: OFF, 1-3: decreasing symptoms to ON state) individually, based on
kinematics. In the screening period, we performed 64-channel electroencephalography
measurements simultaneously with electromyography and motion detection during a resting
state, finger tapping, hand grasping tasks, and pronation-supination of the arm, with
the four levels of contralateral stimulation. We analyzed spectral power at the low
(13-20 Hz) and high (21-30 Hz) beta frequency bands and low (31-60 Hz) and high (61-100
Hz) gamma frequency bands using the dynamic imaging of coherent sources. Structural
equation modelling estimated causal relationships between the slope of changes in
network beta and gamma activities and the slope of changes in bradykinesia measures.Activity
in different subnetworks, including predominantly the primary motor and premotor cortex,
the subthalamic nucleus predicted the slopes in amplitude and speed while switching
between stimulation levels. These subnetwork dynamics on their preferred frequencies
predicted distinct types and parameters of the movement only on the contralateral
side.Concurrent subnetworks affected in bradykinesia and their activity changes in
the different frequency bands are specific to the type and parameters of the movement;
and the primary motor and premotor cortex are common nodes.
