Their take on “How It Works.”
1) FMRI studies show that when subjects receive electroacupuncture, there is much less activity in four different pain-processing regions of the brain. The brain “notices” the pain less. A fifth region-the anterior insula, which governs the expectation of pain, quiets down too, so adding to the pain reduction. Sham acupuncture only affects the insula or the expectation region. (I have never heard it explained this way, and will have to study up a bit to see if that jives with what the studies say, since there is much study of Default Mode Networks, which may mean the same thing…)
2)Acupuncture activated endogenous opiates. Imaging shows that mu-opiod receptors have improved binding after acupuncture. Brain scans have also helped to validate the importance of “de qi” in the analgesic effect.
Left unsaid is the effect on the autonomic nervous system that has been documented extensively in this blog and elsewhere.