針刺合谷穴對體感覺誘發電位正波300的影響

Effect of Acupuncture at Hegu (LI-4) Point on the P300 of the Somatosensory Evoked Potentials (SEPs)

體感覺誘發電位，係體感覺周邊神經受到刺激所產生的反應，此種反應沿著體感覺傳導徑路，由周邊神經傳向脊髓、腦幹、視丘及大腦皮質感覺區。而在300毫秒(msec)左右會出現一正波稱之為P300，與受測者的認知能力有很高的相關性，包括訊息傳導、刺激評估、記憶、情緒、思考、計數、專心及清醒程度等，屬於高級大腦皮質的活動功能。當受測者的認知能力或低時，P300的潛期會延長，振幅會降低。本研究的目的，是想了解在正常人之上肢食指產生具疼痛感的電流刺激，然後針刺合谷穴，觀察P300的潛期與振幅是否會改變。本研究資料結果顯示，P300在針刺得氣15分鍾的潛期高於針刺前的潛期，且此差異這統計土顯著水準，而振幅在此階段之變化則為針刺得氣15分鐘低於針刺前，只在Pz及C3'處達統計的顯著水準；潛期和振幅在取針後20分鐘與針刺前之變化和針刺得氣15分鐘與針刺前之變化相同，即有潛期延長及振幅降低之趨勢；取針後40分鐘和針刺前之比較，亦顯示有潛期延長及振幅降低的趨勢，然而此趨勢變得不明顯，只有在C3'處達統計的顯著水準。因此，針刺合谷穴會改變體感覺誘發電位中的P300，即會改變受測者對食指疼痛的認知能力，使P300的潛期延長，振幅降低。

Somatosensory evoked potential is the reaction induced by stimulation the peripheral sensory nerve and conducted along the sensory pathway to the cortical sensory area. Wave P300 is a long-latency (about 300 msec), high amplitude positive component of event-related potentials. It represents the cognitive functions, including memory, calculation, and Concentration etc. When the cognitive functions decrease, a lengthening in latency and a decrease in amplitude of P300 wave is observed. The aim of this study is to evaluate the change of wave P300, which is induced by an electrical stimulus applied to the index lingers of the subjects, before, duriang and after acupuncture at Hegu (LI-4) points. The study design used in this study is ”within-group comparison”, which compares the values of P300 waves at different time periods among the same individuals. The results showed that during acupuncture latency increased significantly while amplitude at Pz and C3' decreased significantly, and that the levels were maintained for 20 minutes after removal of needles. Forty minutes after removal of needles, both latency and amplitude returned to pre-acupuncture levels.