Sugar Cravings May Soon Be Stopped by Rewiring Brain, Scientists Say

Scientists have untangled the connection between food and pleasure in a study where they turned off sugar cravings in mice.

The team at Columbia University's Zuckerman Institute were able to switch off the pleasure mice gained from sugary food by tinkering with the neurons in a part of the brain in charge of emotions. And while mice and humans are far from the same, the authors believe the study could pave the way for new treatments for obesity and eating disorders such as anorexia.

Previously, the team showed that special cells on the tongue send signals to specific parts of the brain which decide whether a substance is sweet, bitter, salty, sour or umami. This sparks the accompanying response in the body, like pleasure or disgust.

In their latest study, the researchers focused on how the amygdala processes sweet and bitter tastes and found that different parts of this region of the brain are especially programed to determine different tastes, and work together with the taste cortex.

Dr. Li Wang, a postdoctoral research scientist at Zuckerman Institute's Zuker lab and first author of the study published Nature said in a statement: "This segregation between sweet and bitter regions in both the taste cortex and amygdala meant we could independently manipulate these brain regions and monitor any resulting changes in behavior."

In mice, the researchers switched on and off the parts of the amygdala which process sweet and bitter flavors. When scientists turned on the sweet connection, mice responded to water like it was sugar. By manipulating other connections in the amygdala, they made sweetness distasteful, and bitterness attractive.

And when the researchers turned off the flavor regions of the amygdala but didn't tamper with the taste cortex, the mice could tell the difference between sweet and bitter flavors without the expected emotional responses.

"It would be like taking a bite of your favorite chocolate cake but not deriving any enjoyment from doing so," said Dr. Wang. "After a few bites, you may stop eating, whereas otherwise you would have scarfed it down."

Dr. Charles S. Zuker, a principal investigator at Columbia's Mortimer B. Zuckerman Mind Brain Behavior Institute and the paper's senior author, said in a statement: "When our brain senses a taste it not only identifies its quality, it choreographs a wonderful symphony of neuronal signals that link that experience to its context, hedonic value, memories, emotions and the other senses, to produce a coherent response."

He told The Guardian that the results suggest the positive perception of sweet foods is likely down to an innate, evolutionary need to find foods high in energy.

The study suggests that the parts of the brain which trigger an emotional response to different tastes can be isolated and turned off separately. The amygdala could one day therefore be the basis of treatments for eating disorders.

But first, the researchers must look into how the regions of the brain linked to taste are also involved in how we move, learn and store memories.

"Our goal is to piece together how those regions add meaning and context to taste," said Dr. Wang. "We hope our investigations will help to decipher how the brain processes sensory information and brings richness to our sensory experiences."