Somato–Autonomic Reflexes of Acupuncture

Objective: Acupuncture, as an important part of Traditional Chinese Medicine, has been practiced for thousands of years in China and now all over the world, but the underlying neuroanatomical basis is still poorly understood. This article explores how acupuncture drives autonomic reflexes and why the widely used Streitberger sham-needling control should be revisited. Method: This article summarizes modern studies, suggesting that functional connections between somatic tissues and internal organs may be explained via somato-autonomic reflexes. Results: Modern studies have revealed a few organizational rules regarding how acupuncture drives distinct somatosensory autonomic pathways, including acupoint selectivity and intensity dependence. Activation of these autonomic pathways modulates various body physiologic functions, such as gastrointestinal motility and systemic inflammation. Meanwhile, extensive anatomical and functional characterization of the somatosensory system raises a question about the widely used Streitberger sham-needling control. Specifically, the skin epidermis and hair follicles contain mechanically sensitive afferents, whose activation by this sham stimulation could modulate pain and the autonomic nervous system. Conclusions: A deeper understanding of the underlying neuroanatomical basis of acupuncture is crucial for optimizing stimulation parameters and designing proper sham-controls to demonstrate and improve the efficacy and the safety of using this modality to treat human conditions.