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Brain's binge eating circuit revealed

sugar binge

Imagine being able to program your brain against binge eating (Source: KatarzynaBialasiewicz/iStockphoto)

Constant craving A new animal study has brought the dream of reprogramming your brain against binge eating and sugar addiction one step closer, say researchers.

A team from Massachusetts Institute of Technology report today in the journal Cell they have identified and disrupted a brain circuit in laboratory mice to stop them bingeing.

Importantly, they say, this circuit is quite independent of that which controls normal eating.

"The most exciting thing is that we now know that it is possible to disrupt compulsive sucrose seeking without disrupting the desire to eat when you are hungry," says neuroscientist Dr Kay Tye.

Addiction to food, like addiction to drugs, is a compulsive behaviour believed to form as a result of habits that encourage certain circuitry in the brain.

"Compulsive behaviour is something you do in the face of a negative consequence, or even when you don't need it," says Tye.

This includes bingeing on biscuits and cakes, despite the fact you know it is likely to make you fat and you're not even hungry.

Tye's research suggests it may be possible to reprogram the brain to treat such compulsive eating behaviours.

"Imagine if the future treatment for obesity was something where you just go in and get your neural circuits reprogrammed so you don't compulsively overeat or you don't crave sugar, but you still want to eat healthy food," she says.

Sounds ideal, doesn't it? But for this to be possible, the circuits involved in binge eating would need to be separate from those involved in normal feeding so you did not disrupt the latter when deactivating the former.

And this is exactly what Tye and colleagues have found.

Labelling neurones

Previous research led Tye and colleagues to suspect a circuit involving the lateral hypothalamus and the ventral tegmental area of the brain was involved in food addiction.

To test this, they used a technique called optogenetics to painstakingly label hundreds of individual neurones in laboratory mice. They were then able to turn each neurone on or off using light of a particular colour.

When the researchers turned on the suspect circuit in well-fed mice, the animals compulsively overate and sought out a sugary reward, even though they had to cross a metal plate that gave them electric shocks on their feet.

When they turned off the circuit, this behaviour stopped.

When the researchers carried out the experiment in hungry mice they found that the animals would eat the same amount regardless of whether the food addiction circuit was turned on or off.

Tye says this is the first evidence that a food addiction circuit exists and that this circuit is separate to the one controlling normal feeding.

"So we can shut down this pathway, we can reduce compulsive sucrose seeking and compulsive overeating when an animal is full. But if an animal is hungry it will still eat just as much as it would otherwise. So it does not affect hunger-motivated eating at all."

Evolution of the binge

Tye says the circuit that causes us to binge in modern day society likely evolved as a survival mechanism, driving early humans to stock up on food when they got the chance so they could survive long winters.

Now, however, food is available everywhere and our bodies and brains are not adapted to this new environment, says Tye.

She says habits developed when you are young are likely to prime the food addiction circuit so we develop problems like sugar addiction.

"Not everybody has an issue with craving sucrose but I think exposure to high sugar foods, especially early on in life can predispose you to have compulsive sucrose seeking," says Tye.


Tye says there is evidence that it might be possible to use treatments such as deep brain stimulation to deactivate the food addiction circuit.

"Most synapses in the brain are plastic and they can be strengthened or weakened," she says. "This circuit could just be weakened and reduce compulsive sucrose seeking. I don't see any reason why that's not possible."

She emphasised much more work required to show this would work in humans and is safe.

Tags: diet-and-nutrition, obesity, neuroscience