Sometimes it can feel impossible to say ‘no’ to a second slice of cake, even after a hearty meal. Now, scientists have found a brain circuit that could help to explain why it is so easy to overindulge.
Working in mice, Scott Sternson at Janelia Research Campus in Ashburn, Virginia, and his colleagues identified a region of the brainstem that is home to a set of neurons whose activity is influenced by food or water intake. The scientists found that activating the neurons inhibited eating, whereas blocking their activity caused mice to eat or drink more and for longer than usual, even if the animals were well fed and hydrated.
The researchers served the mice a variety of liquids while monitoring the neurons’ activity. The team found that neuronal activity was reduced when mice drank water or bitter-tasting compounds — but the reduction was even more marked when mice consumed tasty drinks such as a vanilla-flavoured beverage.
This suggests that a neural feedback loop allows the consumption of palatable food or drinks to trick the brain into wanting more.