MRI studies reveal the neurological mechanisms of acupuncture on human health. Research published in Autonomic Neuroscience demonstrates that stimulation of specific acupuncture points induces hemodynamic changes in specific brain networks. The researchers add that brain networks accessed by specific acupuncture points relate to specific medical disorders and suggest an "acupoint-brain-organ" pathway.

Functional magnetic resonance imaging (fMRI) studies reveal specific acupuncture point effects in the brain through blood-oxygen-level dependent (BOLD) measurements. In a meta-analysis of 82 fMRI studies, researchers found a large body of evidence supporting acupuncture point specificity. This applies to both manual acupuncture and electroacupuncture. True acupuncture point stimulation induced specific cortical effects whereas sham acupuncture did not. In addition, the researchers note that acupuncture point stimulation produces significantly "more positive and negative hemodynamic signal response(s) in brain regions compared with sensory stimulation used as a control condition."

Many important findings were confirmed. Acupuncture exerted a stimulus that "could induce beneficial cortical plasticity in carpal tunnel syndrome patients." It was also demonstrated that acupuncture relieved pain "by regulating the equilibrium of distributed pain-related central networks."

The researchers note that a fundamental principle of Traditional Chinese Medicine (TCM) is that "specific acupoints have therapeutic effects on target organ systems remote from the needling site…." Recent fMRI investigations support this principle. The researchers note that "fMRI investigations regarding several acupoints have demonstrated that acupuncture stimulation at disorder-implicated acupoints modulates the activity of the disorder-related brain regions."

In TCM, acupuncture point Neiguan (PC6) is indicated for the treatment of nausea and vomiting. The fMRI research supports this ancient principle. The researchers note, "Acupuncturing at Neiguan (PC6) could selectively evoke hemodynamic response of insula and cerebellar-hypothalamus in order to exert modulatory effects on vestibular functions, indicating the specific treatment effect on nausea and vomiting."

Acupuncture point GB37 (Guangming), located on the lower leg, is indicated for the treatment of vision related disorders within the TCM system. The name of the point, Guangming, is translated as bright light and indicates the acupoint’s use in the treatment of visual disorders. It is categorized as a Luo-connecting point and has the TCM functions of regulating the liver and clearing vision. The point is indicated for the treatment of hyperopia (farsightedness), myopia (nearsightedness), night blindness, and eye pain. The research demonstrates that GB37 increases neural responses in the occipital cortex. The researchers add that it was "discovered that modulations in vision-related cortex (BA18/19) were responsive to the specificity of GB37…." This connection between fMRI findings and TCM indications confirms the specificity of GB37 for the treatment of visual disorders.

Many examples of acupoint cortical specificity were included in the research. The following are some highlights. The researchers note, "Acupuncture at the three classical acupoints of Hegu (LI4), ST36 and Taichong (LV3) produced extensive deactivation of the limbic-paralimbic-neocortical brain network as well as activation of its anti-correlated activation network." Differentiation between the points was noted as the following, "LI4 was predominant in the pregenual cingulated and hippocampal formation, ST36 response was predominant in the subgenual cingulate, and LV3 in the posterior hippocampus and posterior cingulated…." Taixi (KI3) mediated the executive network, Qiuxu (GB40) activated the auditory network, and "Jiaoxin (KI8) was associated with (the) insula and hippocampus in pain modulation."

The mechanisms of cerebral action of true acupuncture were found distinct from sham acupuncture. The researchers note, "Acupuncture at Taichong (LR3) could specifically activate or deactivate brain areas related to vision, movement, sensation, emotion, and analgesia compared with sham acupuncture." They add, "Several studies have found that there were different brain responses between traditional acupoints and sham points…." It was found that "ST36 could induce greater activation in ventrolateral periaqueductal gray (PAG) and produced linearly time-variant fMRI activities in limbic regions, such as amygdale and hippocampus…." Needling acupuncture point Erjian (LI2) activated the insula and operculi but this did not occur with sham acupuncture. Other research examples were cited. The researchers concluded, "These results provided evidence to support that acupoints may have its own functional specificity to sham point."

Reference
He, Tian, Wen Zhu, Si-Qi Du, Jing-Wen Yang, Fang Li, Bo-Feng Yang, Guang-Xia Shi, and Cun-Zhi Liu. "Neural mechanisms of acupuncture as revealed by fMRI studies." Autonomic Neuroscience (2015).