The abstract from Dr. Harris’ talk at ISAMS with some emphases of my own incorporated. This is from 2011 and has been in draft form all this time.
Presentation here.2_Harris_Presentation

Central Neural Actions of Acupuncture, Insights from Brain Imaging
Richard Harris PhD, Assistant Professor, Chronic Pain and Fatigue Research Center Department of Anesthesiology, University of Michigan
Functional neuroimaging has been used to study the mechanistic effects of acupuncture for the past 12 years. Over this time researchers have found specific effects of acupuncture on the central nervous system, both in healthy controls as well as in diseased populations. These effects appear to be largely divergent from the “placebo effect”. An investigation of the temporal dynamics of acupuncture yields a complex array of actions on the central nervous system.
During needle insertion and manipulation, acupuncture activates sensory cortical regions while deactivating the limbic system. The degrees of these effects are distinct from the sensation of pain and are related to the “De Qi” sensation. These effects are also more prevalent during electrical stimulation as compared to manual needle manipulation. Following needle removal, modulation of brain connectivity is observed wherein cortical and brain stem regions alter connection strengths between the pain network as well as the Default Mode Network. These effects may be related to analgesia. Over the course of long-term therapy, with multiple treatment sessions, there is a build-up of effects that involve synaptic plasticity and/or changes in synaptic strengths, involving dynamic regulation of neurotransmitter receptors. Finally, immediate actions of acupuncture on the nervous system are modulated over the course of therapy such that the effects of one acupuncture session may be different from a subsequent session. Acupuncture effects are clearly complex and multifactorial, having impact on the central nervous system as assessed by multiple neuroimaging methods.