Phase coupling in the beta and gamma frequencies of motor cortex activity is elevated in people with Parkinson's disease when medication is temporarily withheld.

OBJECTIVE

How neuronal oscillatory activity in Parkinson's disease (PD) is organized and coordinated is not yet known. We hypothesized that cross-frequency phase synchrony (CFS) in the beta and gamma frequencies measured over the motor cortex [using electroencephalography (EEG)] at rest would be elevated in people with PD compared with healthy controls. ON- versus OFF-medication tests in the PD group were further compared with the hypothesis that elevated CFS would be found in the OFF-medication state.

METHODS

CFS in beta and gamma frequencies was estimated in EEG recordings from 15 people with mild-moderate Parkinson's and in 15 control participants.

RESULTS

Beta-gamma CFS in the motor cortices was increased in the PD OFF tests compared with tests of the control group. As a whole-brain control analysis, large-scale beta-gamma CFS in all 32 channels was found to not differ between groups, thereby isolating abnormal beta-gamma CFS to the motor cortex in PD OFF.

CONCLUSION

New evidence describes brain oscillatory patterns in people with mild-moderate PD, which might pave avenues for early diagnosis and treatments.