Brain-tinkering study makes sugar taste vile

Research holds promise for war on obesity

Have you ever been on a diet and wished that spinach excited your taste buds? Or that chocolate left you cold?

Neuroscientists said on Wednesday they have discovered how to manipulate the brain to make sweet things off-putting, and bitter ones nice.

But only in mice, for now. Mooting promise for an obesity treatment, researchers in the US said they have learnt to “switch” parts of the brain’s “amygdala” on and off, turning sweetness into an aversive taste for lab mice, and bitterness into a desirable one.

“The research points to new strategies for understanding and treating eating disorders including obesity and anorexia nervosa,” said a statement from the Columbia University’s Zuckerman Institute, whose researchers took part in the study.

The method has yet to be tested in humans, however. In the study, published in the scientific journal Nature, the researchers focused on the amygdalae.

In humans, these are a pair of almond-sized organs in the temporal lobe known to play a role in emotions like fear and pleasure, as well as motivation, survival instinct and stress processing.

Previous research had shown that the amygdala connects directly to the taste cortex of the brain, the team said.

The new work reveals that the amygdala has separate sweet and bitter regions, just like the taste cortex.

As a result, “we could independently manipulate these brain regions and monitor any resulting changes in behaviour” in lab mice, said study coauthor Li Wang.

The team used laser light stimulation to artificially “switch on” neuron connections to sweet or bitter regions of the amygdala.