Once the acupuncture needle penetrates the skin, fascia and muscle, nerve endings are stimulated, sending action potentials (i.e. nerve signals) to the spinal cord, then the midbrain from where they then pass to other areas of the brain.
One of these areas is the somatosensory cortex which processes sensory information and registers the needle sensation, usually felt as a deep, dull, ache, numbness or tingly feeling. Needling should not be aversively painful - if it is the needle should be removed.
The action potentials then stimulate other parts of the brain such as the prefrontal cortex, limbic system, hippocampus, cerebellum and very importantly, the hypothalamus. The hypothalamus can be thought of as the brain's central controller, which influences other parts of the brain, the nervous system and hormonal systems.
The medical acupuncture experience, created by an experienced practitioner, has been shown to modulate different brain networks. A brain network can be thought of as different parts of the brain working together in a coordinated way to achieve a specific function.
One important network is the default mode network which regulates the body's resting state. The body must wind down from a stress state and restore itself to a resting state regularly; otherwise, persistent stress-related illness and disease may occur over time.
When applied gently and regularly for a more extended period (at last 20 minutes), one of the therapeutic benefits of medical acupuncture is bringing the body back to a more balanced resting state. Acupuncture is, therefore, useful to help reconstruct the self at a central level, by regulating the default mode network, improving connectivity between brain areas
The clinical benefits of improved regulation of the default mode network are:
- Improved sense of self-awareness and being, even if pain symptoms persist.
- Improved memory function, learning and information retention.
- Improved social evaluation and interactions.
- Improved ability to rest and relax.
In summary, medical acupuncture's central regulatory effects, which occur regardless of where the needles are inserted, significantly impact various brain networks, including the default mode network. The therapeutic benefits, especially for those who find the effects of stress challenging, can be very beneficial.
T. Lundeberg. Karolinska Institutet. Department of Physiology and Pharmacology MD PhD Acc Professor. BMAS Conference Proceedings, 28th November 2020.
Raichle ME. The brain's default mode network. Annual review of neuroscience. 2015 Jul 8;38:433-47.
Mars RB, Neubert FX, Noonan MP, Sallet J, Toni I, Rushworth MF. On the relationship between the “default mode network” and the “social brain”. Frontiers in human neuroscience. 2012 Jun 21;6:189.