1Athinoula A. Martinos Center, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States; 2Athinoula A. Martinos Center, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States; 3Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States; 4Neurobiology Research Unit, Rigshospitalet and University of Copenhagen, Copenhagen, DK-2100, Denmark
Simultaneous fMRI-PET provides unique advantage to relate neurochemical events (signaled by changes in selective receptor for binding) to neural activity (indexed by changes in BOLD signals). In this study, we present the first simultaneous fMRI-PET in human to investigate the engagement of opioid system during experimental pain, and how it compares to functional responses. Both fMRI and PET show great activation in response to pressure pain. fMRI reveals more activation than PET, including S1, SMA, and anterior cingulate. While PET and fMRI demonstrates many overlapping activations in the basal forebrain, such as the caudate/nucleus accumbens and thalamus. These areas are part of the pain descending control system responsible medicating pain through releasing endogenous opioid peptides.