The After-Effects of Theta Burst Stimulation Over the Cortex of the Suprahyoid Muscle on Regional Homogeneity in Healthy Subjects.

Xiuhang Ruan,Cuihua Gao,Xinhua Wei,Guangqing Xu,Sijing Zhang,Xinqing Jiang,Yanli Liu,Guoqin Zhang,Xin Chen,Yue Lan,Lisheng Jiang,Lingling Liu

doi:10.3389/fnbeh.2019.00035

Abstract

Theta burst stimulation (TBS) is a powerful variant of repetitive transcranial magnetic stimulation (rTMS), making it potentially useful for the treatment of swallowing disorders. However, how dose TBS modulate human swallowing cortical excitability remains unclear. Here, we aim to measure the after-effects of spontaneous brain activity at resting-state using the regional homogeneity (ReHo) approach in healthy subjects who underwent different TBS protocols over the suprahyoid muscle cortex. Sixty healthy subjects (23.45 ± 2.73 years, 30 males) were randomized into three groups which completed different TBS protocols. The TMS coil was applied over the cortex of the suprahyoid muscles. Data of resting-state functional MRI (Rs-fMRI) of the subjects were acquired before and after TBS. The ReHo was compared across sessions [continuous TBS (cTBS), intermittent TBS (iTBS) and cTBS/iTBS] and runs (pre/post TBS). In the comparison between pre- and post-TBS, increased ReHo was observed in the right lingual gyrus and right precuneus and decreased ReHo in the left cingulate gyrus in the cTBS group. In the iTBS group, increased ReHo values were seen in the pre-/postcentral gyrus and cuneus, and decreased ReHo was observed in the left cerebellum, brainstem, bilateral temporal gyrus, insula and left inferior frontal gyrus. In the cTBS/iTBS group, increased ReHo was found in the precuneus and decreased ReHo in the right cerebellum posterior lobe, left anterior cerebellum lobe, and right inferior frontal gyrus. In the post-TBS inter-groups comparison, increased ReHo was seen in right middle occipital gyrus and decreased ReHo in right middle frontal gyrus and right postcentral gyrus (cTBS vs. cTBS/iTBS). Increased ReHo was shown in left inferior parietal lobule and left middle frontal gyrus (cTBS vs. iTBS). Increased ReHo was shown in right medial superior frontal gyrus and decreased ReHo in right cuneus (cTBS/iTBS vs. iTBS). Our findings indicate cTBS had no significant influence on ReHo in the primary sensorimotor cortex, iTBS facilitates an increased ReHo in the bilateral sensorimotor cortex and a decreased ReHo in multiple subcortical areas, and no reverse effect exhibits when iTBS followed the contralateral cTBS over the suprahyoid motor cortex. The results provide a novel insight into the neural mechanisms of TBS on swallowing cortex.

Highlights

Swallowing is a complex activity involving a widely distributed neuronal network, and a body of evidence indicates that cortical and subcortical areas play a crucial role in swallowing control (Hamdy et al, 1999b; Humbert and Robbins, 2007; Martin et al, 2007)
regional homogeneity (ReHo) comparisons were made between post-theta burst stimulation (TBS) and pre-TBS conditions in the three groups
In group 2, compared to the baseline, post-intermittent TBS (iTBS) induced an increase in ReHo in the bilateral precentral

Summary

Introduction

Swallowing is a complex activity involving a widely distributed neuronal network, and a body of evidence indicates that cortical and subcortical areas play a crucial role in swallowing control (Hamdy et al, 1999b; Humbert and Robbins, 2007; Martin et al, 2007). The usual clinical practice to manage post-stroke dysphagia is to provide nutritional support via alternative feeding methods and behavioral adaptations (e.g., modifying food consistencies, compensatory maneuvers); the efficacy of these methods is controversial and needs high-quality evidence to verify it (Bath et al, 2000). Against this background, development of an effective intervention that improve swallowing function through promoting functional recovery with concept of neuroplasticity in the early course of stroke will be helpful in restoring swallowing functions of post-stoke dysphagia (Pisegna et al, 2016). A few studies have attempted to explore the after-effects induced by TBS on cortical excitability by using motorevoked potentials (MEPs) for recording, whereas the effects of cortical spontaneous brain activation have not been assessed (Mistry et al, 2007, 2012)

Objectives

Methods

Results

Conclusion