经皮穴位电刺激诱发的大脑fMRI信号与镇痛的关系

针刺主要是通过激发内源性阿片达到镇痛的目的。不同个体针刺镇痛效果的差异 ,与胆囊收缩素 (ＣＣＫ)等抗阿片物质的个体水平有关 ,那么 ,ＣＣＫ是通过何种通路来影响针刺镇痛的呢 ?我们应用功能性磁共振成像 (ｆＭＲＩ)针对这个问题进行了研究。实验采用两种频率 (2Ｈｚ,1 0 0Ｈｚ)的经皮穴位电刺激 (ＴＥＡＳ)模拟针灸的不同手法 ,其优点是镇痛效果肯定 ,刺激参数可以量化。以前的研究表明 ,不同的脑内神经通路分别介导低频和高频ＴＥＡＳ镇痛 ,中脑、丘脑和下丘脑的某些核团起着关键性的作用。 2 5名健康被试者随机分成两组 ,分别接受高…

Correlation between Acupoint-stimulation Evoked Cerebral Functional Magnetic Resonance Signals and Analgesic Effect

Acupuncture can mobilize endogenous opioid system and produce analgesia. However, there is some variability of the analgesic effect between individuals, which is related with cholecystokin level of the subject. In the present study, we try to use functional magnetic resonance imaging (fMRI) to address the question by which neuropathways CCK influences acupuncture induced analgesia. Two different frequencies of transcutaneous electric acupoint stimulation (TEAS) were administered to normal human body. TEAS was used instead of traditional acupuncture for its similar analgesic effect and convenience of parameter adjustment. Our previous studies have indicated that low and high frequency TEAS generated effects through different neuropathways, in which some nuclei of midbrain, thalamus and hypothalamus played an important role. 25 healthy volunteers were randomly divided into two groups to receive low and high frequency TEAS respectively. Data from functional MRI scanning (EPI sequence, TR=3000 ms, TE=45 ms, Flip angle: 90°) were collected at the same time of stimulation. Basal and after TEAS pain thresholds were measured by radiant heat withdrawal test 1～3 days before fMRI examination and changes of pain threshold were calculated as the index of analgesic effect of TEAS. Functional data were processed with cross correlation of timecourse and stimulation curve after registration, normalization and detrending. The averaged signal intensity of every interested region was linear regressed according to the change of pain threshold. We found that in low frequency TEAS group, activation intensity of contralateral primary and supplementary motor areas (MI and SMA), bilateral secondary somatosensory area (SⅡ), contralateral thalamus and anterior cingulate cortex (BA 24), ipsilateral superior temporal gyrus, insula had a significant linear correlation with the change of pain threshold. Furthermore, the signal intensity of bilateral hippocampus and the change of pain threshold had a negative linear correlation. While in the areas of primary somatosensory area (SⅠ) and inferior parietal lobule (BA 40), such linear correlation did not exist. In the case of high frequency TEAS, the results were similar to those mentioned above, that is, the corresponding somatosensory areas and the connective cortex were all activated. While the relevant motor related areas were seldom activated. Parts of the limbic system such as bilateral amygdala, perigenual anterior cingulate cortex, nucleus accumbence, and premedial frontal cortex, were inhibited, among which signals of amygdala and nucleus accumbence were negatively related with the analgesic effect. Our results suggested that different frequencies of TEAS stimulation activated different brain areas. Some brain areas are specifically involved in the TEAS analgesia process. They may play an important role in the acupuncture analgesic neuropathways.