This article by “friend of blog” Vitaly Napadow, looks at resting brain connectivity as a biomarker for pain and pain relief in fibromyalgia patients. He doesn’t mention acupuncture as the treatment modality used, but I emailed him and he said acupuncture was the non-medicinal modality.

Decreased intrinsic brain connectivity is associated with reduced clinical pain in fibromyalgia.
Napadow V, Kim J, Clauw DJ, Harris RE.Arthritis Rheum. 2012 Jan 31.
Source

Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129; Department of Radiology, Logan College of Chiropractic, Chesterfield MO, 63006. vitaly@nmr.mgh.harvard.edu.
Abstract
OBJECTIVE:

A major impediment toward the development of novel treatment strategies for fibromyalgia (FM) is the lack of an objective marker which tracks with spontaneous clinical pain report. Resting state intrinsic brain connectivity in FM has demonstrated increased insular connectivity to the default mode network (DMN), a network whose activity is increased during rest. Moreover increased insular connectivity to the DMN was associated with increased spontaneous pain levels. However as these analyses were cross-sectional in nature, they provided no insight to dynamic changes in connectivity and their relationship with variation in clinical pain report.
METHODS:
17 FM patients underwent resting state fMRI at baseline and following 4 weeks of a non-pharmacological intervention to diminish pain. Intrinsic DMN connectivity was evaluated using probabilistic independent component analysis. A paired analysis evaluated longitudinal changes in intrinsic DMN connectivity and a multiple linear regression investigated correlations between longitudinal changes in clinical pain and changes in intrinsic DMN connectivity. Changes in clinical pain were assessed with the Short Form of the McGill Pain Questionnaire (SF-MPQ).
RESULTS:

Clinical pain was reduced following therapy (SF-MPQ sensory scale: p<0.02). Intrinsic DMN connectivity to the insula was reduced, and this reduction was correlated with reductions in pain (corrected p<0.05).
CONCLUSIONS:
Our findings suggest that intrinsic brain connectivity can be used as a candidate objective marker that tracks intra-subject with changes in spontaneous chronic pain in FM. We propose that intrinsic connectivity measures could potentially be used either in research or clinical settings as a complementary, more objective outcome.