After-meal snack cravings? It’s the work of food-seeking neurons, not hunger

Feeding control via midbrain-subthalamic pathway.

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Craving snacks after a meal might be due to active food-seeking neurons, not hunger. UCLA psychologists found a brain circuit in mice that drives them to seek food, even when they are full. If this holds for people, it may shed light on eating disorders. The study published in Nature Communications discloses a novel finding: brainstem cells devoted to food-seeking.

Corresponding author Avishek Adhikari, a UCLA associate professor of psychology, said, “This region we’re studying is called the periaqueductal gray (PAG). It is in the brainstem, which is very old in evolutionary history, and because of that, it is functionally similar between humans and mice. “Although our findings were surprising, it makes sense that food-seeking would be rooted in an ancient part of the brain since foraging is something all animals need to do.”

Adhikari explores how fear and anxiety help animals assess risks. While studying fear, his team discovered a brain region linked to fear and panic. They found that activating a specific cluster of neurons in this region caused mice to focus on foraging and feeding rather than fear. 

To study this, they used a virus to make brain cells light-sensitive, allowing them to control neural activity with a laser and record it with a miniature microscope.

Mice with their vgat PAG cells stimulated with laser light became motivated to explore their environment and chase after crickets. This behavior was motivated by the desire for rewarding food rather than hunger. Mice with activated cells craved fatty foods even when whole, willing to endure discomfort. Dampening cell activity reduced foraging, even in hungry mice.

When this circuit is active in mice, it causes obsessive feeding regardless of the consequences; when it is inactive, mice don’t go for food even when hungry. It could affect a person’s predilection for sweet, fatty foods over vegetables.

Humans likely have similar brain cells, suggesting overactivity could lead to excessive eating, while underactivity may contribute to anorexia. If confirmed, targeting this circuit could treat eating disorders.

The study demonstrates how brain circuits affect eating behaviors and emphasizes the role that food-seeking neurons play in producing cravings following meals. Researchers aim to understand these mechanisms better to develop treatments for compulsive eating and related disorders in animals and humans.

Journal reference:

  1. Reis, F.M.C.V., Maesta-Pereira, S., Ollivier, M. et al. Control of feeding by a bottom-up midbrain-subthalamic pathway. Nature Communications. DOI: 10.1038/s41467-024-46430-5.
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