Background & aims: Although brain registration of subliminal somatic stimulations such as masked visual stimuli and their influence on electrical and hemodynamic measures of cerebral activity have been reported previously, there have been no reports on cerebral cortical registration of subliminal visceral stimulation. Because studies evaluating the consequences of subliminal somatic stimulation have shown that subliminal stimulation can effect behavior, it is conceivable that such subliminal messages from the intestine could potentially influence intestinal sensory/motor function or effect the perception/interpretation of sensory signals originating from the gut.
Methods: We studied the cerebral cortical functional magnetic resonance imaging (fMRI) response to subliminal, liminal, and supraliminal rectal distention in healthy volunteers.
Results: Study findings indicate that subliminal afferent signals originating from the gut are registered in the cerebral cortex without reaching the level of awareness. Locations of cortical activity caused by intestinal subliminal stimulation are similar to those of liminal and supraliminal stimulation but their intensity and volume are significantly lower (P < 0.05).
Conclusions: Subliminal afferent signals originating from the gut are registered in the cerebral cortex and induce changes in measures of brain activity, such as hemodynamic changes detectable by fMRI.