Laser acupuncture lights up the brain for depression

A fascinating study published in PLoS One (the Public Library of Science) documents the increase in metabolic activity in specific brain regions related to depression elicited by the application of laser light to acupuncture points (one of the methods for peripheral sensory-based neuromodulation of the brain that we routinely use). The authors state their intent:

"As laser acupuncture is being increasingly used to treat mental disorders, we sought to determine whether it has a biologically plausible effect by using functional magnetic resonance imaging (fMRI) to investigate the cerebral activation patterns from laser stimulation of relevant acupoints."

They stimulated 4 acupoints (LR14, CV14, LR8 and HT7—indicated for depression in TCM)  and a sham point with a fiber-optic infrared laser, alternating the stimulation with a fake laser. The measured the effect on the whole brain by recording changes in the blood oxygenation level-dependent (BOLD) fMRI response with a 3T scanner (and resolved changes in localized metabolic activity—brain cells 'working'). What did the data show?

"Many of the acupoint laser stimulation conditions resulted in different patterns of neural activity. Regions with significantly increased activation included the limbic cortex (cingulate) and the frontal lobe (middle and superior frontal gyrus). Laser acupuncture tended to be associated with ipsilateral brain activation and contralateral deactivation that therefore cannot be simply attributed to somatosensory stimulation."

A simple way to think of depression is a failure of the frontal lobes to 'fire' adequately. This research adds to the body of evidence that peripheral sensory-based modalities—stimulating sensory nerve endings such as acupoints and trigger points by various methods elicits a brain response. As we have found, this has practical significance in the treatment of depression. The note in their conclusion:

"We found that laser stimulation of acupoints lead to activation of frontal-limbic-striatal brain regions, with the pattern of neural activity somewhat different for each acupuncture point...Differing activity patterns depending on the acupoint site were demonstrated, suggesting that neurological effects vary with the site of stimulation."