Neuroscientists are starting to understand how thirst works in the mammalian brain, and in some cases, how it doesn’t.
Blood sensors deep in the brain measure salt concentrations and trigger the impulse to drink when they’re out of balance, but different species compensate for deficiencies in unusual ways: we drink, but squirrels suppress the impulse to drink during hibernation.
These sensory organs are just some of the many throughout the body that monitor environment and feed information to the brain; scientists are still trying to understand how they work and how they communicate with the brain.
The universality of thirst-related neural circuitry means that while everyone feels thirst, we each experience it differently: humans primarily drink water to compensate, while other animals eat more food or seek out certain plants.
Differential pressure sensors in different parts of the body measure the water content of different tissues, and some cells respond mechanically to the presence of water.
In addition to water, the brain monitors blood for signs of salt deficiency and triggers the ingestion of salt, but it does not usually do so via a conscious desire (as with thirst), but rather through taste.
