Does acupuncture produce a BOLD-signal? New findings with fMRI on stimulation of acupoint GB 37

INTRODUCTION The acceptance of acupuncture as a therapy of organic diseases has increased rapidly even though the exact mechanisms of acupuncture are still unknown. Most studies, however, suggest that the effect of acupuncture is transmitted through the neuronal system (1). By means of fMRI, we aim to scrutinize whether or not focal cerebral activity is elicited by acupuncture. Recent studies investigating the BOLD-signal changes in the visual cortex correlated to acupuncture reported diverse results (2, 3). In our former study the BOLD-response of the visual cortex to optical stimulation was not significantly modulated by acupuncture nor was a BOLD-response detected correlating with acupuncture (3). In our present study the acupuncture of the acupoint Guangming (GB 37), documented to influence vision related disorders (4), was intensified. Acupuncture was performed bilaterally and a manual twisting manipulation of the needles was added. This manipulation intensified the so-called ‘‘De-Qi’’Phenomenon, a local tingling sensation which according to classic literature is essential for the effectiveness of acupuncture. Being aware that the visual stimulation might interfere with the cortical effects of acupuncture, in a part of the subjects only the acupuncture protocol was applied omitting the visual stimulation. METHODS This study was performed on a 2 T whole body system (BRUKER S200 Avance) equipped with a head gradient insert (30 mT/m, 150 T/m/s). Acquisition parameters were: single-shot GE-EPI, matrix size: 64 x 64, square FOV: 25 cm, 12 slices, slice thickness: 4 mm, interslice distance: 6 mm, TEeff: 35 ms, TR: 3 s. Altogether 17 healthy volunteers were investigated using identical acupuncture protocols, 11 of them with additional visual stimulation, 6 of them without. The needles were inserted bilaterally during the 200 and removed during the 540 timeframe. The needles were twisted in intervals of one minute during acupuncture. 2 different kinds of functional maps were obtained by cross-correlation analysis relating to: needle insertion (before vs. after) and needle twisting (12 s before vs. 12 s after). Visual stimulation: red goggles flickering at 8 Hz, 7 visual stimulation-cycles alternated with 7 non-stimulation-cycles; visual stimulation-cycle: 2 activation periods, 2 rest periods, 30 s each. 40 images were acquired per cycle, except during needle insertion. Then, 120 images were acquired in order to distinguish between effects related to needle application and the visual stimulus. Functional maps of visual activation for each individual cycle were calculated by cross-correlation analysis. Fig.1 displays the timing of acupuncture and visual stimulation.