| Objective:Local and distal acupoint selection are the basic principles of acupoint selection.In this study,electroacupuncture(EA)LI4 and ST2 was performed on healthy subjects to observe the changes of hand and face representations in bilateral motor cortex.It was aimed to explore the effects of intra-hemispheric inhibition and inter-hemisphere inhibition and provide a modern scientific basis and new ideas for acupoint selection.Methods:Twenty healthy volunteers were included in the study,including 6 males and 14 females,aged 19-31 years,with an average of 23.2 years.Using the crossover design(self-contrast control),all subjects were randomized to receive three interventions,including LI4 EA group,ST2 EA group,and double sham EA group.The elution period between the groups was half of a month.The EA frequency of LI4 and ST2 was set to 2 Hz,the intensity was 0.5-1.5 mA,and the time was lasting for 30 minutes.Double sham EA group was intervened with a pragmatic placebo needle and an adhesive pad without skin penetration attaching to a connecting cord with a broken inner wire of the electroacupuncture apparatus.With the technology of transcranial magnetic stimulation(TMS),the magnetically stimulated motor-evoked potentials(MEPs)of hand representation dominated by the left first dorsal interosseous muscle(FDI)and face representation dominated by the bilateral orbicularis oculi(00)were recorded immediately before and after EA.Then the total amplitude of MEPs,the number of effective stimulus sites and the center of gravity were calculated.The study is registered in the Acupuncture Clinical Trial Registry.The title of the study is:Study on the effect of ipsilateral and contralateral motor cortex induced by electroacupuncture LI4 and ST2 acupoints in healthy subjects.The registration number is AMCTR-100-20000323.Results:1.Baseline comparison:Before EA,the differences with hand and face representations in the total amplitude of MEPs,the number of effective stimulus sites and the center of gravity in bilateral motor cortex in each group were not statistically significant.2.Comparison of changes in the total amplitude of MEPs(cortical excitability)before and after EA in each group(1)Comparison within the group①In LI4 EA group,compared with that before EA,the total amplitude of MEPs in the contralateral motor cortex was increased significantly in hand representation(P=0.000<0.05)and decreased significantly in face representation(P=0.004<0.05).②In ST2 EA group,compared with that before EA,the total amplitude of MEPs was increased significantly in face representation in the contralateral motor cortex(P=0.017<0.05)and decreased significantly in face representation in the ipsilateral motor cortex(P=0.000<0.05).③In double sham EA group,compared with that before EA,the total amplitude of MEPs had no significant changes in hand and face representation of right motor cortex and face representation of left motor cortex(P>0.05).(2)Comparison between groupsTwo pairs of comparisons were made between the groups.Compared with double sham EA group,the total amplitude of MEPs had significant differences in hand and face representation of right motor cortex in LI4 EA group,hand representation:(P=0.000<0.05),face representation:(P=0.002<0.05).Compared with double sham EA group,the total amplitude of MEPs had significant differences in face representation of bilateral motor cortex in ST2 EA group,face representation in left motor cortex:(P=0.010<0.05),face representation in right motor cortex:(P=0.000<0.05).3.Comparison of changes in number of effective stimulus sites(area)before and after EA in each group(1)Comparison within the group①In LI4 EA group,compared with that before EA,the area in the contralateral motor cortex was increased significantly in hand representation(P=0.000<0.05)and not different in face representation(P>0.05);②In ST2 EA group,compared with that before EA,the area of face representation in the bilateral motor cortex had no difference(P>0.05);③In double sham EA group,compared with that before EA,the area had no significant changes in hand and face representation of right motor cortex and face representation of left motor cortex(P>0.05).(2)Comparison between groupsTwo pairs of comparisons were made between the groups.Compared with double sham EA group,the area in right motor cortex had significant difference in hand representation(P=0.013<0.05)and no difference in face representation in LI4 EA group(P>0.05).Compared with double sham EA group,the area in bilateral motor cortex had no difference in face representation in ST2 EA group(P>0.05).4.Comparison of changes in the center of gravity before and after EA in each group(1)Comparison within the group①In LI4 EA group,compared with that before EA,the center of gravity in hand and face representation of the contralateral motor cortex had no difference(P>0.05);②In ST2 EA group,compared with that before EA,the center of gravity in face representation of the bilateral motor cortex had no difference(P>0.05);③In double sham EA group,compared with that before EA,the center of gravity had no significant changes in hand and face representation of right motor cortex and face representation of left motor cortex(P>0.05).(2)Comparison between groupsTwo pairs of comparisons were made between the groups.Compared with double sham EA group,the center of gravity in hand and face representation of contralateral motor cortex had no difference in LI4 EA group(P>0.05).Compared with double sham EA group,the center of gravity in bilateral motor cortex had no difference in face representation in ST2 EA group(P>0.05).Conclusion:1.Under physiological conditions,LI4 EA can induce increased excitability in hand representation and decreased excitability in face representation in the contralateral motor cortex.It prompts that LI4 EA may induce inhibition between different functional areas in a hemisphere(intra-hemispheric inhibition),which has significance in guiding acupuncture theory of selecting acupoints of the corresponding meridian distal to the focus.2.Under physiological conditions,ST2 EA can induce increased excitability in face representation in the contralateral motor cortex and decreased excitability in face representation in the ipsilateral motor cortex.It indicates that ST2 EA may induce inhibition between the same functional area in bilateral hemispheres(inter-hemispheric inhibition),which has significance in guiding acupuncture theory of selecting local acupoints and contralateral acupuncture. |
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