It’s long been thought that neurons that form a hunger circuit in your brain basically determine whether or not you take the next bite of food – that it’s controlling the chewing and swallowing associated with food intake. But a study led by physiologist Zachary Knight of the University of California, San Francisco found in mice that these neurons are actually controlled by the sensory detection of food.

"The discovery suggests that that their primary purpose is actually to promote food discovery – to promote foraging, this act of getting motivated to go out into the world and search for food. Evolutionarily, that makes a lot of sense because if you’re a mouse that’s out in the wild and you probably don’t have access to a lot of food on a regular basis and so the really key decision you need to make is when you are going to risk your life by predation, by going out and searching for food. And so the decision that the mouse really needs to get right, and that evolution would have shaped, is the decision to search for food. So, the neuromechanisms that control the actual decision, to take the next bite are one, probably different and two, probably under weaker control than this decision to search for food."