Objective: To characterize the frontal oscillations during gait observation in Parkinson’s disease (PD) patients with (freezers) and without (non-freezers) freezing of gait.

Background: Freezing of gait, balance, and posture are devastating axial symptoms of PD. Gait and cognition may be interrelated in PD patients. PD-medication and neuromodulation do not reliably improve gait in PD. Previous studies confirm the role of attenuated midfrontal theta (4-7 Hz) activity in cognitive control and amplified motor cortical beta (13-20 Hz) activity in gait and motor control in PD. However, frontal oscillations have not been investigated to understand the cortical recruitment during inactive gait tasks in PD patients with severe gait and cognitive problems.

Method: Here, we collected scalp EEG from freezers, non-freezers, and controls subjects during gait observation task; furthermore, we collected EEG data during gait imagination tasks. The same cortical and associated networks active during real gait are engaged in inactive gait tasks. We also collected baseline resting-state data during eyes closed and eyes opened conditions. All EEG analysis was focused on midfrontal (“Cz”) and left and right motor cortical (“C3” and “C4”) scalp electrodes. PD patients were treated with levodopa.

Results: Freezers showed significantly attenuated theta power and amplified beta power in the midfrontal electrode only during gait observation compared to non-freezers and control subjects. All PD patients showed increased beta power in the left and right motor cortical regions during gait observation. No clear differences in midfrontal theta and beta activity were seen during gait imagination between freezers and control subjects. Furthermore, in the stance and swing phases of a gait cycle during gait observation, theta power was attenuated and beta power was increased in freezers at midfrontal and motor cortical regions.

Conclusion: These findings confirm the functional changes in the frontal cortical region related to gait control. These data suggest that the dynamics of the frontal theta and beta oscillations may contribute to gait or lower-limb movement. Our data may help understand cortical mechanisms of gait dysfunction in advanced PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/abnormal-frontal-theta-and-beta-oscillations-during-gait-observation-in-parkinsons-disease/