Do the neural correlates of acupuncture and placebo effects differ?

The neurophysiological basis of therapeutic acupuncture is not well understood but is likely to consist of both specific and non-specific (e.g. placebo) effects. Data from animal studies suggest that endogenous anti-nociceptive networks may play a large role in therapeutic acupuncture. These networks have also been demonstrated to support placebo analgesia making differentiation between acupuncture specific and non-specific networks challenging. However, modern neuroimaging techniques such as functional magnetic resonance imaging (fMRI), positron emission tomography (PET), electroencephalography (EEG) and magnetoencephalography (MEG) provide a means to safely monitor brain activity in humans and may be used to help map the neural correlates of acupuncture. Recent neuroimaging studies have explored brain activity during acupuncture stimulation and/or the analgesic effects of acupuncture on pain stimulus processing. Although controversy regarding appropriate control methodology (e.g. sham acupuncture) continues, data suggest that modulation of certain limbic brain networks may differentiate between specific and placebo components of acupuncture.