Science Is Still Figuring Out How We Know We're Thirsty

Hunger pangs are pretty straightforward, and once we start eating, we all know that it takes a while for our brains to signal that we're full—which sometimes results in an uncomfortable stuffedness at Thanksgiving or the Indian food buffet. But what about when we're thirsty?

Again, common knowledge is that by the time we're thirsty, we're already dehydrated. If you're us, you can then chug a can of La Croix in two gulps. But how does our body know when our thirst has been satisfied?

Apparently, scientists have been puzzling over our brain's isolated "thirst center" for a few decades now, and NPR reports today on some recent interesting findings in the journal Nature: "The answer appears to be a brain circuit that acts like a water meter, constantly measuring how much fluid we are taking in... The finding appears to explain why our thirst disappears almost immediately when we start drinking."

After all, most animals stop drinking after about a minute, but just like with those hunger pangs, it takes several minutes for the body to become completely hydrated. And overdrinking can have serious consequences. So how do animals know to stop drinking so quickly?

That thirst center apparently acts like a bit of a water meter, cueing the body to stop before things go haywire. Those cells in the thirst center are pretty cagey, as it turns out. The researchers suspect "that the cells can tell the difference between the fast muscle movements of gulping and the slower pace of chewing and swallowing," which enables them to keep close tabs on your body's activities.

What's even weirder is that these scientists were able to manipulate the thirst center cells. With certain stimulation of these neurons in mice, researchers were able to stop the animals from drinking anything at all. While the ability to control brain circuits through manipulation may conjure up unfortunate references to science fiction and horror movies, there are also possible positive implications (although, still a ways off) for those who suffer from depression or schizophrenia. Read more at npr.org today.