Motor cortical oscillations are abnormally suppressed during repetitive movement in patients with Parkinson's disease

Objective: Impaired repetitive movement in persons with Parkinson's disease (PD) is associated with reduced amplitude, paradoxical hastening and hesitations or arrest at higher movement rates. This study examined the effects of movement rate and medication on movement-related cortical oscillations in persons with PD. Methods: Nine participants with PD were studied off and on medication and compared to nine control participants. Participants performed index finger movements cued by tones from 1 to 3 Hz. Movement-related oscillations were derived from electroencephalographic recordings over the region of the contralateral sensorimotor cortex (S1/M1) during rest, listening, or synchronized movement. Results: At rest, spectral power recorded over the region of the contralateral S1/M1 was increased in the alpha band and decreased in the beta band in participants with PD relative to controls. During movement, the level of alpha and beta band power relative to baseline was significantly reduced in the PD group, off and on medication, compared to controls. Reduced movement amplitude and hastening at movement rates near 2 Hz was associated with abnormally suppressed and persistent desynchronization of oscillations in alpha and beta bands. Conclusion: Motor cortical oscillations in the alpha and beta bands are abnormally suppressed in PD, particularly during higher rate movements. Significance: These findings contribute to the understanding of mechanisms underlying impaired repetitive movement in PD.