Let’s say you give a hungry mouse some food – as it eats, you figure it would come satiated and scientists would assume the neurons in its brain would slowly change activity to dampen down the ‘hunger circuit’. Well, that’s not what a team of researchers at the University of California, San Francisco found. In fact, study leader Zachary Knight says no one would have predicted their findings.
"It was entirely, what we would call ‘anticipatory’, meaning that the mouse essentially looks at the food and then predicts the nutritional value of that food. We found that the response of these neurons to the sight and smell of food depends on how palatable the food is."
So, give a mouse “chow”, or ordinary rodent food, and there’s a strong response; but give a mouse chocolate or peanut butter, which they happen to really love, and there’s a very strong response.
"So it's clearly, these neurons are sensing something about what we would call the ‘hedonic’ value of the food, how rewarding it is to eat the food."
These unexpected findings have implications for anti-obesity therapies in humans.