How the brain decides when to drink and eat

A new study by experts from the Max Planck Institute for Biological Intelligence, the University of Regensburg and Stanford University has identified groups of neurons in an area of the brain called the almond-shaped body that are responsible for thirst and hunger. They work along different circuits and shape our need to eat and drink.

The amygdala is traditionally thought to be the center of emotions, but its role in eating habits has been found to be much broader than that. Previously, it was found that it links taste sensations with emotions: pleasant food causes pleasure and unpleasant food causes rejection. What’s more, changes in its activity can cause the body to ignore satiety and keep eating.

A new study has shown that in the same area are special neurons, some of which are responsible solely for thirst, and others regulate both processes at once. If you activate the “thirsty” neurons, the body begins to drink more, if you suppress their activity – conversely, less.

To study the work of these cells used methods that allow you to control their activity with light. Scientists monitored the behavior of mice at different moments – during thirst, hunger and satiety. This helped not only to determine which neurons are activated, but also to track their connections with other parts of the brain.

In addition, the researchers tested how the brain makes decisions by combining need signals with external stimuli. For example, if the mice initially refused a certain flavor of water, after stimulating the right cells, their preferences changed and they began to drink more.

Although the experiments were conducted on rodents, the human almond-shaped body is organized similarly. This opens new perspectives in studying the mechanisms of overeating, anorexia and addictions.

“The sensation of hunger and thirst helps to maintain the balance of nutrients in the body. However, these same processes can lead to disorders if the brain signals are not working properly,” explains study leader Rüdiger Klein.

The scientists now face the challenge of figuring out how the brain regulates competing needs: why does it prioritize food in some situations and water in others? How do emotions influence eating habits? Can these neurons be influenced to fight overeating or anorexia?

The answers to these questions will not only help us to better understand how the brain works, but also possibly create new treatments for eating disorders.