Cortical processing of esophageal sensation is related to the representation of swallowing

Introduction: The esophagus plays a major role in the act of swallowing. The aim of the present investigation was to apply whole-head magnetoencephalography (MEG) in order to study the cortical processing of esophageal sensation in healthy humans in whom the cortical representation of swallowing had been established previously.

Methods: The proximal esophagus was stimulated in 9 subjects by intermittent 5ml water infusion. Submental EMG recording was used to identify trials, which were contaminated by subsequent swallowing.

Results: Esophageal stimulation led to changes in rhythmic activity of the brain that was localized in the left lateral primary sensorimotor cortex. The pattern of cortical activation showed the same hemispheric lateralization as the one of volitional swallowing, however, being localized more lateral.

Discussion: The close anatomical vicinity of these two functions points to an important physiological link between the cortical processing of esophageal sensation and the cortical control of swallowing. Up to now, hemispheric dominance has been described for higher cortical functions like speech and attentional processing as well as for complex motor programs like swallowing. Viewed from this broader perspective, our finding of a functionally significant lateralization of somatosensory input of a midline organ like the esophagus is highly remarkable.