Frontal theta and beta oscillations during lower-limb movement in Parkinson’s disease

Abstract

Background: Motor function and aberrant cognition have been linked in patients with Parkinson's disease (PD), but it is unknown if these are distinct symptoms or if they are correlated outcomes of a single dysfunctional latent process. EEG theta and beta rhythms are reliably associated with cognitive and motor functions, respectably. We tested the hypothesis that PD patients with lowerlimb abnormalities would exhibit abnormal beta and theta rhythms in the mid-frontal region during action initiation. Methods:We recruited thirty-nine subjects, including PD patients with FOG (PDFOG+; n=13) and without FOG (PDFOG-; n=13), and demographically-matched healthy subjects (n=13). Scalp electroencephalogram (EEG) signals were collected during a lower-limb pedaling motor task, which required intentional initiation and stopping of a motor movement.Results: FOG scores were correlated with disease severity and cognition. PDFOG+ patients pedaled with reduced speed and decreased acceleration compared to PDFOG-patients and to controls. PDFOG+ patients exhibited attenuated theta-band (4-8 Hz) power and increased betaband (13-30 Hz) power at mid-frontal electrode Cz during pedaling. Frontal theta-and beta-band oscillations also correlated with lower-limb movement in PD patients. Conclusions:Frontal theta and beta oscillations are predictors of lower-limb motor symptoms in PD. These data provide insight into the mechanism of lower-limb dysfunction in PD, and could be used to design neuromodulation for PD-related lower-limb abnormalities.

Timing variability and midfrontal ~4 Hz rhythms correlate with cognition in Parkinson’s disease

“…Complex cellular factors such as alpha-synuclein and deficits in ascending neurotransmitter systems contribute to PD 11,35 . Despite this complexity, these cellular processes lead to neurophysiological phenomena observable by scalp EEG and intracortical recordings, which have been enormously helpful in both designing medical therapies and targeting brain stimulation sites to address the motor symptoms of PD 33,[36][37][38] . Our results are significant in advancing our neurophysiological understanding of cognitive function in PD because we link PD-related cognitive dysfunction (as measured by MOCA) to midfrontal~4 Hz rhythms, which are a putative cognitive-control mechanism 23 .…”

“…This effort will also require systematic clinical studies using EEGbased biomarkers to assess the usefulness of~4 Hz rhythms in diagnosing cognitive dysfunction, which is often underrecognized in the clinical setting 50 . Of note, we focus on~4 Hz based on extensive human work in PD and cognitive control as well as our animal work [21][22][23]25,28,33 . While~4 Hz deficits may not be highly predictive of PD, our work suggests that interval-timing variability and~4 Hz deficits are predictive of cognition in PD.…”

“…We focused on two key events: the imperative "Go" cue and the keypress. In addition, we focused on the midfrontal electrode Cz in line with our prior work 21,22,[27][28][29]33 . Power-spectral density (PSD) analyses of resting-state data is shown in Supplementary Fig.…”

Neural Correlates of Freezing of Gait in Parkinson's Disease: An Electrophysiology Mini-Review

“…This approach involves the evaluation of frequency bands (25, 94), event-related synchronization (ERS), and desynchronizations (ERD) (95), as well as information flow to examine how a physical manifestation can be correlated to a neural occurrence. In the work by Singh et al, theta and beta bands were evaluated during lower-limb pedaling in PDFoG+ and PDFoG- (96). Results from this study showed that compared to PDFoG-, PDFoG+ exhibited an attenuated mid-frontal theta (4-8 Hz) power, which is associated with impairments in cognitive control (97,98).…”

“…In terms of EEG frequency band analysis, the beta band was shown to increase in the frontal region during lower limb pedaling in PDFoG+, indicating preparatory adjustments and motor plan execution through top-down signaling (118). Also, for PDFoG+ theta band power was attenuated in the mid-frontal location, indicating an impairment in cognitive control (96). In the study that used the dual-task oddball paradigm, although the stimulus was detected by an increased P300, beta ERD was unchanged for PDFoG+.…”