SOMATIC AND LIMBIC CORTEX ACTIVATION IN ESOPHAGEAL DISTENSION - A FUNCTIONAL MAGNETIC-RESONANCE-IMAGING STUDY

Little is known about the cerebral representations of visceral sensati ons in humans. Using functional magnetic resonance imaging (fMRI), we mapped the cortical areas of the human brain that were activated by me chanical stimulation of the esophagus in 5 healthy volunteers. Stimula tion probes were placed into the distal part of the esophagus and infl ated to produce a local distention. The cerebral activation pattern wa s related to the strength and quality of the stimulus. The weakest sti mulus accompanied by a well-localized albeit weak retrosternal sensati on activated only the parietal opercular cortices, probably including the secondary somatosensory cortex (SII). Additional activation of the primary sensorimotor cortex (SI) at the level of the face and mouth r epresentation as well as of the right premotor cortex was found during repetitive distention of the esophagus at 0.5 Hz. Repetitive stimulat ion at 1 Hz additionally activated the insula bilaterally. The stronge st distention stimulus, which caused a painful retrosternal sensation, resulted in an activation of the anterior cingulate cortex. Our findi ngs demonstrate that SII is the primary cortical target of visceral af ferents originating in the esophagus. Limbic structures become engaged when the visceral sensation is unpleasant or painful.