Low-frequency electrical waves in the stomach seem to be synchronised with the activity of a newly discovered resting-state network in the human brain.
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The brain is always active – even when it is at rest, it receives a continuous stream of information from other areas of the body. From gut feelings to heartbeats, this information is constantly monitored to maintain a state of physiological equilibrium known as homeostasis. Signals from the body, including the stomach, also influence a variety of mental processes and complex human behaviours (Critchley and Harrison, 2013; Herbert and Pollatos, 2012; Porciello et al., 2018). Although the anatomy of the homeostatic neural pathway is relatively well known (Craig, 2003), its physiology is less well understood.
During periods of wakeful rest, our brain generates its own spontaneous and synchronised activity within different groups of brain regions (known as resting-state networks). On the other hand, specialised cells in the stomach produce a slow, continuous pattern of electrical impulses that set the pace of stomach contractions during digestion. But the stomach also generates these signals when it is empty, which suggests that they may have another purpose. Now, in eLife, Ignacio Rebollo of the PSL Research University and co-workers – Anne-Dominique Devauchelle, Benoît Béranger, and Catherine Tallon-Baudry – report how they have combined two techniques, functional magnetic resonance imaging and electrogastrography, to shed new light on the interactions between the brain and the stomach (Rebollo et al., 2018).
Rebollo et al. placed electrodes on the abdomen of volunteers as they lay inside a brain scanner and analysed the coupling between the signals from the stomach and the brain using a method called phase-locking value analysis. The researchers discovered a new resting-state network – the gastric network – which fired in synchrony with the rhythm of the stomach (Figure 1A). Furthermore, the various brain regions within this network showed a delayed functional connectivity between each other.
