Time-variant fMRI activity in the brainstem and higher structures in response to acupuncture.
Acupuncture modulation of activity in the human brainstem is not well known. This structure is plagued by physiological artifact in neuroimaging experiments. In addition, most studies have used short (<15 min) block designs, which miss delayed responses following longer duration stimulation. We used brainstem-focused cardiac-gated fMRI and evaluated time-variant brain response to longer duration (>30 min) stimulation with verum (VA, electro-stimulation at acupoint ST-36) or sham point (SPA, non-acupoint electro-stimulation) acupuncture. Our results provide evidence that acupuncture modulates brainstem nuclei important to endogenous monoaminergic and opioidergic systems. Specifically, VA modulated activity in the substantia nigra (SN), nucleus raphe magnus, locus ceruleus, nucleus cuneiformis, and periaqueductal gray (PAG). Activation in the ventrolateral PAG was greater for VA compared to SPA. Linearly decreasing time-variant activation, suggesting classical habituation, was found in response to both VA and SPA in sensorimotor (SII, posterior insula, premotor cortex) brain regions. However, VA also produced linearly time-variant activity in limbic regions (amygdala, hippocampus, and SN), which was bimodal and not likely habituation--consisting of activation in early blocks, and deactivation by the end of the run. Thus, acupuncture induces different brain response early, compared to 20-30 min after stimulation. We attribute the fMRI differences between VA and SPA to more varied and stronger psychophysical response induced by VA. Our study demonstrates that acupuncture modulation of brainstem structures can be studied non-invasively in humans, allowing for comparison to animal studies. Our protocol also demonstrates a fMRI approach to study habituation and other time-variant phenomena over longer time durations.
Napadow
Vitaly
V
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA. vitaly@nmr.mgh.harvard.edu
Dhond
Rupali
R
Park
Kyungmo
K
Kim
Jieun
J
Makris
Nikos
N
Kwong
Kenneth K
KK
Harris
Richard E
RE
Purdon
Patrick L
PL
Kettner
Norman
N
Hui
Kathleen K S
KK
D026881:Acupuncture; D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D001933:Brain Stem / Q000502:physiology*; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D015999:Multivariate Analysis; D010812:Physical Stimulation; D013997:Time Factors; D055698:Touch Perception / Q000502:physiology; D055815:Young Adult