The Immediate Effects of Intermittent Theta Burst Stimulation of the Cerebellar Vermis on Cerebral Cortical Excitability During a Balance Task in Healthy Individuals: A Pilot Study.

Hui-Xin Tan,Qi-Fan Guo,Qiang Gao,Qing-Chuan Wei,Yi Chen,Yun-Juan Xie,Lin He

doi:10.3389/fnhum.2021.748241

Abstract

Objective: This pilot study aimed to investigate the immediate effects of single-session intermittent theta-burst stimulation (iTBS) on the cerebellar vermis during a balance task, which could unveil the changes of cerebral cortical excitability in healthy individuals.Subjects: A total of seven right-handed healthy subjects (26.86 ± 5.30 years) were included in this study.Interventions: Each subject received single-session iTBS on cerebellar vermis in a sitting position.Main Measures: Before and after the intervention, all subjects were asked to repeat the balance task of standing on the left leg three times. Each task consisted of 15 s of standing and 20 s of resting. Real-time changes in cerebral cortex oxygen concentrations were monitored with functional near-infrared spectroscopy (fNIRS). During the task, changes in blood oxygen concentration were recorded and converted into the mean HbO2 for statistical analysis.Results: After stimulation, the mean HbO2 in the left SMA (P = 0.029) and right SMA (P = 0.043) significantly increased compared with baseline. However, no significant changes of mean HbO2 were found in the bilateral dorsolateral prefrontal lobe (P > 0.05).Conclusion: Single-session iTBS on the cerebellar vermis in healthy adults can increase the excitability of the cerebral cortex in the bilateral supplementary motor areas during balance tasks.Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [ChiCTR2100048915].

Highlights

Balance is one of the most a critical function that supports the normal activities of daily life in humans
Single-session intermittent theta-burst stimulation (iTBS) on the cerebellar vermis in healthy adults can increase the excitability of the cerebral cortex in the bilateral supplementary motor areas during balance tasks
We found that single-session iTBS of the cerebellar vermis could increase the concentration of HbO2 in the supplementary motor area (SMA) region during the balance task, but no significant increase was found in the dorsal lateral prefrontal cortex (DLPFC)

Summary

Introduction

Balance is one of the most a critical function that supports the normal activities of daily life in humans. Maintaining balance requires a complex integration and coordination of multiple systems (such as the vestibular system, visual system and auditory system) in the body (Ataullah and Naqvi, 2021). According to the functional divisions of the cerebellum, the three functional areas include the cerebrocerebellum, the spinocerebellum and the vestibulocerebellum These three functional areas all play a vital role in the process of maintaining balance and motor control. The cerebellar vermis plays a key role in balance and motor control. Recent evidence suggests that the cerebellar vermis is critical for maintaining equilibrium and coordinating speech, eye and body movement because the vermis provides information regarding sensations along the extremities, as well as the different stimuli that pertain to balance, visual and auditory processes (Fujita et al, 2020). Study has displayed patients with lesions in the vermis mainly exhibit balance dysfunction (Harris et al, 2018), while patients with lesions in the cerebellar hemispheres mainly exhibit global coordination dysfunction (Carass et al, 2018; Maas et al, 2020)

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