Ipsilateral EEG mu rhythm reflects the excitability of uncrossed pathways projecting to shoulder muscles

Abstract

BackgroundMotor planning, imagery or execution is associated with event-related desynchronization (ERD) of mu rhythm oscillations (8-13 Hz) recordable over sensorimotor areas using electroencephalography (EEG). It was shown that motor imagery involving distal muscles, e.g. finger movements, results in contralateral ERD correlating with increased excitability of the contralateral corticospinal tract (c-CST). Following the rationale that purposefully increasing c-CST excitability might facilitate motor recovery after stroke, ERD recently became an attractive target for brain-computer interface (BCI)-based neurorehabilitation training. It was unclear, however, whether ERD would also reflect excitability of the ipsilateral corticospinal tract (i-CST) that mainly innervates proximal muscles involved in e.g. shoulder movements. Such knowledge would be important to optimize and extend ERD-based BCI neurorehabilitation protocols, e.g. to restore shoulder movements after stroke. Here we used single-pulse transcranial magnetic stimulation (TMS) targeting the ipsilateral primary motor cortex to elicit motor evoked potentials (MEPs) of the trapezius muscle. To assess whether ERD reflects excitability of the i-CST, a correlation analysis between between MEP amplitudes and ipsilateral ERD was performed.MethodsExperiment 1 consisted of a motor execution task during which 10 healthy volunteers performed elevations of the shoulder girdle or finger pinching while a 128-channel EEG was recorded. Experiment 2 consisted of a motor imagery task during which 16 healthy volunteers imagined shoulder girdle elevations or finger pinching while an EEG was recorded; the participants simultaneously received randomly timed, single-pulse TMS to the ipsilateral primary motor cortex. The spatial pattern and amplitude of ERD and the amplitude of the agonist muscle’s TMS-induced MEPs were analyzed.ResultsERDs occurred bilaterally during both execution and imagery of shoulder girdle elevations, but were lateralized to the contralateral hemisphere during finger pinching. We found that trapezius MEPs increased during motor imagery of shoulder elevations and correlated with ipsilateral ERD amplitudes.ConclusionsIpsilateral ERD during execution and imagery of shoulder girdle elevations appears to reflect the excitability of uncrossed pathways projecting to the shoulder muscles. As such, ipsilateral ERD could be used for neurofeedback training of shoulder movement, aiming at reanimation of the i-CST.

Correlation between the ERD in grasp/open tasks of BCIs and hand function of stroke patients: a cross-sectional study

“…Task-related modulation in EEG-based SMRs is usually manifested as event-related desynchronization (ERD) or event-related synchronization (ERS) in low-frequency components [mu rhythm (8–12 Hz) and beta rhythm (13–26 Hz)] [ 13 ]. MI, MA, or ME is associated with ERD of mu rhythm oscillations recordable over SMC (electrode sites C3 and C4 according to the 10/20 system) using EEG [ 14 , 15 ]. ERD usually appears when SMR decreases, it happens in active motion, such as MI, while ERS means that SMR increases, which usually happens in the termination of movement or MI [ 16 ].…”

On closed-loop brain stimulation systems for improving the quality of life of patients with neurological disorders

“…Transcranial magnetic stimulation (TMS) Problems with the motor cortex have been extensively studied by using TMS, with 18 articles dedicated to the issue: those by Ros et al ( 2010 ), Niazi et al ( 2012 ), Sitaram et al ( 2012 ), Mokienko et al ( 2013 ), Takemi et al ( 2013 , 2018 ), Hänselmann et al ( 2015 ), Kaplan et al ( 2016 ), Royter and Gharabaghi ( 2016 ), Schildt et al ( 2016 ), Hasegawa et al ( 2017 ), Mashat et al ( 2017 ), Daly et al ( 2018 ), Jochumsen et al ( 2018 ), Syrov et al ( 2020 ), Ding et al ( 2021 ), Grigorev et al ( 2021 ), and Mihelj et al ( 2021 ) for neugodegenerative disease. The second most commonly studied disease by using TMS was stroke, with five articles devoted to it: those by Gharabaghi et al ( 2014 ), Syrov et al ( 2019 ), Cantillo-Negrete et al ( 2021 ), Hayashi et al ( 2022 ), and Liang et al ( 2020 ).…”

The Effects of Priming Intermittent Theta Burst Stimulation on Movement-Related and Mirror Visual Feedback-Induced Sensorimotor Desynchronization

“…However, as an exploratory study, there is no similar existing study from which to calculate an appropriate sample size. We followed previous ERD research and simply used an empirically estimated sample size of 10 cases in each group (Hasegawa et al, 2017). Second, we did not include behavioral outcomes for evaluation in this study.…”