The switch in the brain that regulates appetite has been located by scientists and could mean they will be able to ‘turn off’ overeating.
They looked at cells in the hippocampus region and discovered a link to a ‘circuit’ responsible for balanced eating.
In the study, experts identified a group of cells, known as hD2R neurons, that become active whenever a mouse was fed.
When these cells were stimulated, the mice ate less – but when they were silenced, researchers found that they ate more.
As a result, the researchers found that hD2R neurons responded to the presence of food by deterring animals from eating.
Dr Estefania Azevedo, a postdoctoral associate at Rockefeller University, New York, said: “These cells keep an animal from overeating.
“They appear to make eating less rewarding and, in that sense, are tuning the animal’s relationship to food.”
She was joined in the study by Professor Paul Greengard and postdoctoral associate Dr Jia Cheng of Rockefeller University.
They said the cells are used to stop an animal from overeating – which could open them up to predators in the wild.
In the study, the team stimulated the neurons of mice as they wandered around a food-filled environment to test their memory.
Previous studies have shown that animal brains evolved to remember the past location where meals were found effectively.
Researchers found that hD2R stimulation actually prevented the mice from returning to an area where food was previously found.
This suggests that the activation ‘somehow diminished meal-related memories’.
Dr Azevedo said: “Mental connections between food and location are important for survival, and the strength of these connections is regulated by how rewarding an experience is.
“Because hD2R neurons affect an animal’s relationship with food, it also ends up affecting these connections.”
Further experiments showed that the neurons receive input from the entorhinal cortex, which processes sensory information.
This information is sent out to the septum, which is involved in feeding.
Researchers said they are the first to find that these neurons serve as a regulatory checkpoint between sensing food and eating.
Dr Azevedo added: “Our study shows that brain areas involved in cognitive processing and memory formation affect feeding behaviour.
“So it is possible that, with training, people may be able to learn to change their relationship to food.”
The research, published in the Neuron journal, suggested that the brain has elaborate mechanisms for fine-tuning appetite.