Acupuncture is generally thought to rely on Aδ fibre stimulation for its effects and the role of C fibres has been largely discounted. Recent research, however, shows that there are C tactile fibres in humans that respond to light touch and project to the limbic system. They are thought to be responsible for feelings of calm and wellbeing that are elicited by gentle manual stimulation, as in stroking. These findings are likely to be relevant to acupuncture as regards both clinical practice and research. They may explain why even superficial acupuncture with brief needle insertion can have a clinical effect and why light touch may not be an adequate control procedure for use in clinical trials.
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