Subsequent Acupuncture Reverses the Aftereffects of Intermittent Theta-Burst Stimulation

Abstract

Objective: This study explored whether acupuncture affects the maintenance of long-term potentiation (LTP)-like plasticity induced by transcranial magnetic stimulation (TMS) and the acquisition of motor skills following repetitive sequential visual isometric pinch task (SVIPT) training.

Methods: Thirty-six participants were recruited. The changes in the aftereffects induced by intermittent theta-burst stimulation (iTBS) and followed acupuncture were tested by the amplitude motor evoked potential (MEP) at pre-and-post-iTBS for 30 min and at acupuncture-in and -off for 30 min. Secondly, the effects of acupuncture on SVIPT movement in inducing error rate and learning skill index were tested.

Results: Following one session of iTBS, the MEP amplitude was increased and maintained at a high level for 30 min. The facilitation of MEP was gradually decreased to the baseline level during acupuncture-in and did not return to a high level after needle extraction. The SVIPT-acupuncture group had a lower learning skill index than those in the SVIPT group, indicating that acupuncture intervention after SVIPT training may restrain the acquisition ability of one's learning skills.

Conclusion: Acupuncture could reverse the LTP-like plasticity of the contralateral motor cortex induced by iTBS. Subsequent acupuncture may negatively affect the efficacy of the acquisition of learned skills in repetitive exercise training.

Keywords: acquisition of learned skills; acupuncture; cortical excitably; long-term potentiation; sequential visual isometric index finger abduction task.

FIGURE 1

Experimental design. (A) In the intermittent theta-burst stimulation (iTBS) group, the baseline of motor evoked potential (MEP) amplitudes induced by transcranial magnetic stimulation (TMS) with the iTBS scheme over the primary motor cortex (M1) under resting conditions was measured for 10 min, then the LTP-like plasticity induced by iTBS was measured by TMS elicited MEP for 35 min. In the iTBS-acupuncture group, the changes of MEP were tested at pre- and post-iTBS for 10 min, then measured under acupuncture-in and off for 30 min after iTBS intervention. (B) Both groups carried on sequential visual isometric pinch task (SVIPT) training for 30 min, but the SVIPT-acupuncture group was given additional acupuncture after SVIPT training. After 10 min of SVIPT intervention, two needles were inserted into the Quchi and Waiguan acupoints and kept in the upper limb of the training side for 30 min and then extracted. The learning skill index was evaluated by video recorder continuously over 5 consecutive days.

FIGURE 2

The SVIPT program. Participants were seated with the left shoulder and elbow flexed and the forearm in a neutral position and fixed on the upper limb exoskeleton of the intelligent feedback training system (IFTS). The radial side of the index finger and thumb was tightly attached to the columnar sensor. Participants learned to control column pressure to reach the target number range.

FIGURE 3

Effect of iTBS and acupuncture on MEPs. Time-course changes of MEPs following iTBS in panel (A) and iTBS and subsequent acupuncture intervention in panel (B). Representative MEP traces following iTBS present an apparent increase, whereas there are traces of a decrease in MEP amplitude after subsequent acupuncture intervention.

FIGURE 4

Averaged changes in the MEP amplitude at pre and after iTBS, as well as iTBS with subsequent acupuncture in-off intervention are presented. Data are shown as the mean ± SEM.

FIGURE 5

(A) As practice continued, participants in SVIPT groups obtained an apparent decrease in error rates with either fast or slow metronome velocity. (B) Acupuncture restrained the learning skill index after movement practice. The SVIPT-acupuncture group obtained higher error rates when the test speed was increased.