Effect of Transcutaneous Electrical Nerve Stimulation on Primary Motor Cortex to Modulate Cortical Excitability and Prefrontal Activation during Motor Learning: A TMS and NIRS Study
Date Issued
2014
Date
2014
Author(s)
Shih, Jheng-Kai
Abstract
AIM: The relationship between cranial transcutaneous electrical nerve stimulation (TENS) stimulation and cortical excitability change during motor learning process is unknown. This study aims to explore the effects of cranial TENS application on cortical excitability of primary motor cortex (M1) during implicit sequential motor learning process in normal subjects. Prefrontal activation pattern in learning process was also monitored by Near-infrared spectroscopy (NIRS). METHODS: 48 volunteers were recruited from colleges and communities. Subjects were randomized into TENS stimulation group (Stimulus-TENS/Sham) and TENS stimulation with motor task group (Motor-TENS/Sham). Subjects in both groups need to accomplish two trials (TENS or sham stimulation), the interval between trials was more than 1 week. Motor evoked potential (MEP), intracortical inhibition (ICI) and intracortical facilitation (ICF), Serial reaction time task and NIRS were measured to monitor physiological and behavioral change process in motor learning. RESULTS: MEPs amplitude in both Motor-TENS and Stimulus-TENS group increased significantly. MEP amplitude of Motor-TENS were significantly higher than Stimulus-TENS in followed up 60 mins. Motor task induced synergistic effect on enhancement of MEP amplitude. Higher suppression effects of ICI were also found in both Motor-TENS and Motor-Sham. Motor-TENS go higher suppression of ICI than Motor-Sham which revealed synergistic effect of TENS stimulation. The ICF was also decreased in Motor-TENS and Stimulus TENS. However, between group comparison showed no significant different. In SRTT performance, reaction times significantly improved both in Motor-TENS/Sham but no difference between TENS and sham stimulation. Prefrontal activation showed significant time effect in TENS-Motor only. Increment activation in initial learning and following decrease activation in retention test was observed. Consolidation effect in Motor-TENS than Motor-Sham was also noted. DISSCUSSION: TENS intervention increased corticospinal neuron excitability. However, significant increase suppression induced by ICI may indicate disruption of cortical representation. Increment of ICF concurrent with increment MEP showed ceiling effect existed in ICF measurement. TENS intervention showed weak effect to altered motor learning process. CONCLUSION: TENS stimulation increase cortical excitability and inhibitory shift of intracortical circuits. Motor practice played a facilitation role to altered cortical excitability which induced synergistic effect on TENS intervention. Further study should be done to investigate the effect of TENS with long-term (more than 24 hour) effect or increase times of stimulus program.
Subjects
經皮神經電刺激
經顱磁刺激
近紅外線吸收光譜
內隱式順序性動作學習
神經塑性
Type
thesis
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