Regional brain activation during proximal stomach distention in humans: A positron emission tomography study

Background & Aims: Hypersensitivity to proximal gastric distention due to abnormal central nervous system processing of visceral stimuli has been suggested as a possible underlying pathophysiologic mechanism in functional dyspepsia. However, the cortical regions activated by distention of the proximal stomach have not been identified. The aim of this study was to investigate regional brain activation during painful and nonpainful proximal gastric distention in humans. Methods. Positron emission tomography of the brain was performed in 11 healthy volunteers during 4 conditions: (1) no distention and isobaric distention to the individual thresholds for (2) first, (3) marked, and (4) unpleasant sensation. Data were analyzed using statistical parametric mapping. Results: During maximal distention relative to baseline, significant (P-corrected less than or equal to .05) regional brain activation occurred in the left and right gyrus postcentralis (Brodmann area [BA] 43), the left gyrus temporalis superior (BA 38), the right gyrus frontalis inferior (BA 47, orbitofrontal cortex), the right midanterior cingulate gyrus (BA 24), the right anterior insula, and the left cerebellar hemisphere. These areas showed a progressive increase in activation with increasing intensity of the distending stimulus. Conclusions: We found evidence for a neuronal network processing distention stimuli of the proximal stomach that is overall consistent with the "visceral stimulation network" described in the literature. In addition, we found activation of the orbitofrontal cortex, confirming its role as a convergence zone for processing of food-related stimuli and regulation of hunger, appetite, satiety, and food intake. We found no evidence for a functional neuroanatomic divergence in the processing of noxious and innocuous gastric stimuli.