The Time-dependent Effects Of Acupuncture At Quchi And Zusanli Acupoints On Excitability And Plasticity Over The Motor Cortex

Objective:The aim of this study was to investigate the effects of acupuncture at "Quchi(LI11)and Zusanli(ST36)acupoints on the bilateralized motor cortex(M1)excitability and long-term potentiation(LTP)plasticity in healthy volunteers.Methods:Study was divided into three parts.(1)In the first session,eighteen subjects were randomly divided into acupuncture group(n=9)or sham acupuncture group(n=9)with random number table method.Motor evoked potential(MEP)amplitudes induced by transcranial magnetic stimulation(TMS)over the bilateralized M1 in resting conditions were measured at the'Before'(15min before acupuncture),'In'(30min with the needle in situ)and 'After'(30min after the needle removal)phases,at 30 second intervals;(2)The seconed session,the LTP-like plasticity induced by paired associative stimulation(PAS)was explored,which was consisted of 200 pairs of electrical stimulation of ulnar nerve at the FDI followed by TMS over the bilateralized M1,TMS-MEP amplitudes over the bilateralized M1 in resting conditions were measured at the 'Before','In' and 'After' phases;(3)The last session,the motor practice(MP)was tested,subjects were asked to perform repeated(rate 0.1 Hz),externally paced voluntary finger movements by briefly contracting the first dorsal interosseous muscle(FDI)in a twitch-like fashion.Results:1.The effects of acupuncture on motor cortex excitability.(1)Compared with before acupuncture,MEP amplitudes for the contralateral to the acupuncture sites were significantly depressed when the needle in situ(P<0.01),while MEP amplitudes for the ipsilateral were facilitated MEP amplitudes(P<0.01);MEP amplitudes for the bilateral were facilitated MEP amplitudes after the needle removal(P<0.01);(2)Compared with before acupuncture,there was no significant change with the sham needling group.2.The effects of acupuncture on LTP-like plasticity.(1)Compared with before acupuncture,MEP amplitudes for the contralateral to the acupuncture sites were depressed when the needle in situ,the changes were no significant(P>0.05);(2)Compared with before acupuncture,MEP amplitudes for the ipsilateral were facilitated MEP amplitudes when the needle in situ(P<0.01),and MEP amplitudes for the bilateral were facilitated MEP amplitudes after the needle removal(P<0.01).3.The effects of MEP amplitudes by contracting FDI externally paced voluntary finger movements.(1)Compared with before acupuncture,MEP amplitudes for the contralateral to the acupuncture sites were significantly depressed when the needle in situ(P<0.01),and MEP amplitudes were more depressed by contracting FDI externally paced voluntary finger movements when the needle in situ(P<0.01);(2)Compared with before acupuncture,MEP amplitudes for the ipsilateral were facilitated when the needle in situ(P<0.01),and MEP amplitudes for the bilateral were significantly facilitated MEP amplitudes by contracting FDI externally paced voluntary finger movements after the needle removal(P<0.01).Conclusion:The excitability as well as the LTP-like plasticity of the bilateralized M1 could be modulated by acupuncture with single Quchi(LI11)and Zusanli(ST36)acupoints depended on timing in healthy volunteers.