AbstractUnderstanding the neural processes that govern the human gut-brain connection has been challenging due to the inaccessibility of the body’s interior. In this study, we aimed to identify neural responses to gastrointestinal sensation (i.e., the neural basis of ‘gut feelings’) in healthy humans using a minimally invasive mechanosensory probe. Combining electroencephalography and electrogastrography with signal detection theory measures, we quantified brain, stomach, and perceptual (button-press) responses following the ingestion of a vibrating capsule. The relationship between vibration strength and perceptual sensitivity was evaluated using two stimulation conditions (normal and enhanced). Most individuals successfully perceived capsule stimulation in both conditions, as evidenced by above chance accuracy scores. Perceptual accuracy improved significantly during the enhanced relative to normal stimulation, which was associated with faster reaction time and reduced reaction time variability. Stomach stimulation induced responses in a cluster of parieto-occipital leads near the midline via a late positive potential emerging 300-600 milliseconds after stimulation onset. Moreover, these ‘gastric evoked potentials’ showed dose-dependent increases in amplitude and were significantly correlated with perceptual accuracy. Our findings are consistent with recent neurogastric and optogenetic studies demonstrating a role for posteromedial cortices in gastrointestinal interoception and body dissociation and highlight a unique form of enterically-focused sensory monitoring within the human brain. Overall, these results show that this minimally invasive approach could serve as a useful tool for understanding gut-brain interactions in healthy and clinical populations.Significance StatementThe human brain continuously receives input from the stomach and intestines. These sensations are intuitively incorporated as ‘gut feelings’ into decision-making during daily life, yet we still know very little about how the brain processes gut signals. Here, we developed a minimally invasive approach to studying human gut feelings. In healthy individuals we found that an ingestible vibrating capsule produced reliable changes in both stomach sensation and gastric-evoked brain activity. These changes were significantly associated, in a dose-dependent fashion. We propose that this approach provides an opportunity to better understand the role of gut-related symptoms in human pathological conditions and might yield fundamental insights into how gut feelings are communicated to the human brain.
Event-related and motor responses to probes in a forewarned reaction time task in schizophrenic patients