RESUMEN
<p><b>OBJECTIVE</b>Effects of inter-individual variability on fMRI of acupuncture were observed and the possible influencing factors were further analyzed.</p><p><b>METHODS</b>Twenty-six healthy volunteers were selected. And acupuncture was applied at Zusanli (ST 36) on the left side with even manipulation. The same experimental designation and data collecting reference were adopted to collect functional data. Then, the same data processing method was applied for analyzing individual data. Data which did not confirm with data analyzing qualification were rejected. The 26 individual data which met the requirement were taken randomly for 5 times according to the principle of random group division. Five groups named with A, B, C, D and E were thus generated with 11 samples in each. Images were processed with the AFNI software for every group, and the activated brain areas were revealed.</p><p><b>RESULTS</b>Activated areas in the brain were observed in all the 5 groups, and the results vary a lot among different groups. Decreased signals of activated brain areas were observed in group C, while increased signals were seen in group D. Partial increasing and partial decreasing signals appeared in the other 3 groups. Compared with other groups, group D demonstrated totally different activated areas. The rate of difference among different groups is 46.7%-100.0%, and most of the differences were over half of the activated areas.</p><p><b>CONCLUSION</b>Under the pre-requisites of strict control of experimental designation, acupuncture method, data collecting and processing, great differences have been found in the activated areas of the brain. It indicates that obvious individual differences existes in the activated areas of the brain with acupuncture. And the difference may greatly influence the researching result of fMRI as well as conclusions of those results.</p>