Sweet tooth? New research finds desire for sugar can be eliminated by rewiring brain

Answer: Ghantewala Halwai (Image: Pixabay)

A new research in mice has revealed that the brain’s underlying desire for sweet, and its distaste for bitter, can be erased by manipulating neurons in the amygdala, the emotion centre of the brain.

The researchers also established that the removal of the animal’s capacity to crave for a taste does not affect its capability of identifying one. The findings suggest that the brain’s complex taste system — which produces an array of thoughts, memories and emotions when tasting food — are actually discrete units that can be individually isolated, modified or removed altogether.

“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,” said Charles S. Zuker, a principal investigator at Columbia’s Mortimer B Zuckerman Mind Brain Behaviour Institute and the paper’s senior author.

The researchers building on an earlier work identified when the tongue encounters one of the five basic tastes — sweet, bitter, salty, sour or umami — specialised cells on the tongue send signals to specialised regions of the brain so as to identify the taste, and trigger the appropriate actions and behaviours.

Focusing on sweet and bitter taste, they found that there was a clear divide between the sweet and bitter regions of the taste which extended to the amygdala.

The researchers tried to manipulate the brain by switching on and off the regions and registered the response of the mice. For example, when the sweet connections were turned on, the animals responded to water just as if it were sugar.

When the researchers instead turned off the amygdala connections but left the taste cortex untouched, the mice could still recognise and distinguish sweet from bitter, but now lacked the basic emotional reactions, like a preference for sugar or aversion to bitter.

“It would be like taking a bite of your favourite chocolate cake but not deriving any enjoyment from doing so,” said Li Wang, a postdoctoral research scientist in the Zuker lab and the paper’s first author. “After a few bites, you may stop eating, whereas otherwise, you would have scarfed it down.”

The study breaks the notion that the identity of a food and the pleasure one feels when eating it are intertwined. Although the work on the subject is still ongoing, but if successfully migrated to humans, it could well have an answer to our sweet tooth.

The research paper has been published in Nature.