The Mystery of Thirst: How the Brain Senses Dehydration

New research reveals the mechanism by which the brain senses thirst. Instead of directly detecting water deficiency, the brain monitors blood salt concentration through circumventricular organs near the hypothalamus, such as the OVLT and SFO. When salt concentration is too high or the water-salt ratio is imbalanced, these organs signal the brain, triggering thirst. Interestingly, the brain doesn't wait for water absorption to determine hydration; it uses sensors in the mouth and gut to quickly estimate water intake, shutting off the thirst signal promptly. This suggests thirst isn't simply a water deficiency signal, but rather the brain's 'educated guess' about the body's internal environment.