Effect of Electro-Acupuncture on Lateralization of the Human Swallowing Motor Cortex Excitability by Navigation-Transcranial Magnetic Stimulation-Electromyography

Xiaorong Tang; Mindong Xu; Jiayi Zhao; Jiahui Shi; Yingyu Zi; Jianlu Wu; Jing Xu; Yanling Yu; LuLu Yao; Jiayin Ou; Yitong Li; Shuqi Yao; Hang Lv; Liming Lu; Nenggui Xu; Lin Wang

doi:10.3389/fnbeh.2022.808789

Effect of Electro-Acupuncture on Lateralization of the Human Swallowing Motor Cortex Excitability by Navigation-Transcranial Magnetic Stimulation-Electromyography

Front Behav Neurosci. 2022 Feb 24:16:808789. doi: 10.3389/fnbeh.2022.808789. eCollection 2022.

Authors

Xiaorong Tang¹, Mindong Xu¹, Jiayi Zhao¹, Jiahui Shi¹, Yingyu Zi², Jianlu Wu¹, Jing Xu¹, Yanling Yu¹, LuLu Yao¹, Jiayin Ou¹, Yitong Li³, Shuqi Yao⁴, Hang Lv², Liming Lu¹, Nenggui Xu¹, Lin Wang¹

Affiliations

¹ South China Research Center for Acupuncture and Moxibustion, Medical College of Acu-Moxi and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, China.
² Nanfang Hospital, Southern Medical University, Guangzhou, China.
³ Shenzhen Maternity and Child Healthcare Hospital, Shenzhen, China.
⁴ Department of Integration of Chinese and Western Medicine, School of Basic Medical Sciences, Peking University, Beijing, China.

Abstract

Background: The use of transcranial magnetic stimulation combined with electromyography for the functional evaluation of the cerebral cortex in both clinical and non-clinical populations is becoming increasingly common. Numerous studies have shown that electro-acupuncture (EA) can regulate cerebral cortical excitability. However, the effect of EA on the lateralization of the human swallowing motor cortex excitability is not yet fully understood.

Objective: The aim of this study was to assess whether lateralization is present in the swallowing motor cortex of healthy subjects, and to investigate the impact of EA at Lianquan (CV23) and Fengfu (GV16) on lateralization.

Methods: Forty subjects were randomized 1:1 into the EA group and the sham-EA group. The bilateral swallowing motor cortices was located by a neuroimaging navigation system. Then, the resting motor threshold (RMT) and motor evoked potential (MEP) of the mylohyoid of healthy subjects were recorded while applying combined transcranial magnetic stimulation and electromyography before and after EA or sham-EA.

Results: First, the RMT and MEP latency of the contralateral mylohyoid innervated by the right swallowing cortex (71.50 ± 1.67%, 8.30 ± 0.06 ms) were lower than those innervated by the left (79.38 ± 1.27%, 8.40 ± 0.06 ms). Second, EA at CV23 and GV16 reduced the bilateral RMT and enhanced the bilateral MEP latency and amplitude (P = 0.005, P < 0.001; P = 0.002, P = 0.001; P = 0.002, P = 0.009), while sham-EA did not (P > 0.05). Third, EA had an effect on the RMT and MEP latency in terms of lateralization changes, but this was not significant (P = 0.067, P = 0.156).

Conclusion: The right swallowing motor cortex of healthy subjects is more excitable than that of the left at resting state. Thus, we found that lateralization is present in the swallowing motor cortex of healthy people, which might indicate a hemispheric dominance of swallowing predominates in the right swallowing motor cortex. In addition, EA at CV23 and GV16 can instantly promote the excitability of the bilateral swallowing motor cortices. But there was no significant difference in EA stimulation in terms of lateralization.

Keywords: electro-acupuncture (EA); lateralization; motor evoked potential; resting motor threshold; single-pulse TMS; swallowing.