A multi-institute study led by Monash University has revealed the mechanism that regulates fluid intake in the human body and stops us from over-drinking, which can cause potentially fatal water intoxication.
The study showed that a swallowing inhibition is activated by the brain after excess liquid is consumed, helping maintain tightly calibrated volumes of water in the body.
Swallowing inhibition is probably a “hard-wired” process.
Associate Professor Michael Farrell from the Monash Biomedicine Discovery Institute oversaw the work by University of Melbourne PhD student Pascal Saker as part of a collaboration with several Melbourne institutes.
Building on a previous study, the researchers asked participants to rate the amount of effort required to swallow water under two conditions; following exercise when they were thirsty and later after they were persuaded to drink an excess amount of water.
The results showed a three-fold increase in effort after over-drinking.
Researchers used fMRI to investigate whether swallowing inhibition is present after more water has been drunk than is necessary to restore fluid balance within the body.
Regional brain responses when participants prepared to swallow showed increases in the motor cortex, prefrontal cortices, posterior parietal cortex, striatum, and thalamus after overdrinking, relative to thirst.
Ratings of swallowing effort were correlated with activity in the right prefrontal cortex and pontine regions in the brainstem; no brain regions showed correlated activity with pleasantness ratings.
Researchers conclude that swallowing inhibition is an important mechanism in the overall regulation of fluid intake in humans.
Subjective ratings of swallowing effort provided psychometric confirmation of swallowing inhibition during the oversated condition.
Dehydration impairs your cognitive performance: a meta-analysis
For more information
Overdrinking, swallowing inhibition, and regional brain responses prior to swallowing
Monash Biomedicine Discovery Institute (BDI)
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