A combined [11C]diprenorphine PET study and fMRI study of acupuncture analgesia

Abstract

Functional neuroimaging studies suggest that a lateral network in the brain is associated with the sensory aspects of pain perception while a medial network is associated with affective aspects. The highest concentration of opioid receptors is in the medial network. There is significant evidence that endogenous opioids are central to the experience of pain and analgesia. We applied an integrative multimodal imaging approach during acupuncture. We found functional magnetic resonance imaging signal changes in the orbitofrontal cortex, insula, and pons and [11C]diprenorphine positron emission tomography signal changes in the orbitofrontal cortex, medial prefrontal cortex, insula, thalamus, and anterior cingulate cortex. These findings include brain regions within both the lateral and medial pain networks.

Figure 1

Acupuncture administration procedure. S indicates verum (placebo) acupuncture stimulation at LI4; R indicates rest without stimulation with acupuncture needle still in place. During the fMRI scanning session, imaging data was collected from t = 0 to t =29 minutes. During the PET scanning session, tracer injection and imaging acquisition began at t = 2.

Figure 2

Greater fMRI signal change increases were found during verum acupuncture when compared to sham acupuncture and greater [11C]diprenorphine PET binding potential decreases (suggesting increased endogenous opioid release) were found during verum acupuncture when compared to sham acupuncture.