Scientists find a brain circuit that controls food impulsivity

A pill to stop you craving junk food could be in the pipeline as scientists find a brain circuit that controls impulsive eating in animals

  • Researchers have discovered a circuit in the brain linked to impulse control and overeating 
  • The circuit contains hormones that, when levels increase, our food intake increases as well
  • Rats were trained to push a lever for a food pellet and wait at least 20 seconds to push it for another one
  • When the specific circuit was activated, the rats’ impulse control fell and they were more likely to push the lever before the 20 seconds were over

Scientists have found a specific circuit in the brain, previously linked to overeating, that also alters impulse control. 

Researchers from the University of Georgia say this circuit has hormones that increase food intake, which is what makes us order a bucket full of popcorn when we smell it at the movie theater or grab a tub of ice cream at the supermarket.

In a study conducted on rats, when this pathway was activated, the animals lacked impulse control and more quickly tried to reach food given to them by the scientists. 

The team says the findings suggest that one day, a pill could be developed to target this pathway to stop people from overeating or from craving junk food. 

A new study conducted on rats from the University of Georgia found that when a a specific pathway was targeted, the rats lacked impulse control and more quickly tried to reach food given by the researchers (file image)

‘There’s underlying physiology in your brain that is regulating your capacity to say no to [impulsive eating],’ said lead author Dr Emily Noble, an assistant professor in the UGA College of Family and Consumer Sciences. 

‘In experimental models, you can activate that circuitry and get a specific behavioral response.’ 

For the study, published in the journal Nature Communications, the team looked at subset of brain cells in rats.

These cells, found in the hypothalamus – which regulates bodily functions such as temperature – produce a melanin concentrating hormone (MCH), which controls skin pigmentation. 

But previous studies have found that the same pigment hormone is also involved in appetite. Increasing MCH levels in the brain can increase food intake.

In the new study, the scientists wanted to see if that increased intake was related to impulse control, so researchers trained the rats to press a lever to receive a high-fat, high-sugar pellet.

To receive another one, the rats learned to wait 20 seconds between lever presses. If the rat pressed before the 20 seconds was up, the time would restart.

Researchers then activated an MCH pathway that links the hypothalamus to the hippocampus, which plays a role in learning and memory.

They found that this pathway did not affect how the food tasted nor did it affect the rats’ appetites. 

The circuit only affected the rodents’ impulse control and they were more likely to push the lever before the 20 seconds was up.

‘Activating this specific pathway of MCH neurons increased impulsive behavior without affecting normal eating for caloric need or motivation to consume delicious food,’ Dr Noble said.  

She said she hopes that this lead to a pill that activates the neural pathway to combat overeating and obesity. 

‘Understanding that this circuit, which selectively affects food impulsivity, exists opens the door to the possibility that one day we might be able to develop therapeutics for overeating that help people stick to a diet without reducing normal appetite or making delicious foods less delicious.’

The team says the findings suggest that this could lead to drug treatments for other conditions linked to impulsive behavior such as addiction or gambling.