Objective: To examine brain activity when walking with and without visual cues in Parkinson’s disease (PD).

Background: Gait impairments and Freezing of Gait (FOG) in particular, are common in PD with links to falls risk. Visual cues can improve gait and reduce FOG in PD, but the underlying mechanisms involved are unclear. Understanding how visual cues influence the neural activity involved in walking may allow greater insight into the mechanisms involved in cue response, which could help develop more effective therapeutics. Mobile electroencephalogram (EEG) is a neuroimaging technique that can be useful in investigating neural activity during walking [1].

Method: Forty-three people with PD (Age; 67±6.7, UPDRS-III; 28.6±11.4, ON medication, 23 with FOG (FOG+) and 20 without freezing (FOG-)) walked over-ground for two minutes with and without visual cues (transverse lines to step over) while a 32-channel mobile EEG system (Mobita, TMSi, Netherlands) recorded brain activity and synchronized inertial sensors measured gait. Independent component (IC) analysis in EEGLAB software [2] derived brain activity, specifically source localized IC clusters (via dipoles and K-means) and their power spectral densities; Delta (δ:1-4Hz), Theta (q:4-8Hz), Alpha (α:8-13Hz), Beta (b:13-30Hz) and Gamma (γ:30-50Hz). ICs formed four clusters with source locations in the frontal lobe (FL), supplementary motor area (SMA) and the left and right parietal cortices (PC).

Results: As expected, gait spatio-temporal parameters improved in both FOG+ (stride length improved 12%, p<.001) and FOG- (stride length improved 12%, p<.001) when walking with visual cues. In the FL region, α, b and γ activity was reduced with visual cues compared to no cues (p<0.05) in FOG+, whereas only b and γ activity was reduced in FOG-. In the SMA and left PC regions, b activity was reduced with visual cues compared to no cues (p<0.05) only in FOG+. Lastly, in the right PC region, α activity was increased with visual cues only in FOG- (p<0.05).

Conclusion: Our findings indicate that increased cognitive control of gait and visual processing occurs with visual cues, particularly in FOG+. Walking with visual cue requires altered activation of the FL region compared to walking without cues in PD. Those with FOG+ also showed more activation in the SMA and PC regions than FOG-, which may underpin walking improvement and clinical effect.

References: [1] Stuart, S., et al. (2018). Maturitas. [2] Delorme, A., & Makeig, S. (2004). J neuro meth.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/brain-activity-underpinning-visual-cues-for-gait-impairment-in-parkinsons-disease/