Sweet tooth? Brain-tinkering study makes sugar taste vile

May 30, 2018
Neural projections from the sweet (green) and bitter (red) cortex terminate at distinct targets in the amygdala in the brains of mice. Credit: Li Wang/Zuker Lab/Columbia's Zuckerman Institute

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

Neuroscientists said 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 United States said they have learnt to "switch" parts of the brain's "" on and off, turning sweetness into an aversive 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 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 co-author Li Wang.

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

Have your cake, don't eat it

When sweet connections were turned on, the responded to ordinary water as if it were sugar.

"And by manipulating the same types of connections, the researchers could even change the perceived quality of a taste, turning sweet into an aversive taste, or bitter into an attractive one."

In another experiment, the research turned the amygdala connections "off", but left the taste cortex untouched.

The mice ate, but without showing a preference for sugar, or aversion to bitterness.

"It would be like taking a bite of your favourite chocolate cake but not deriving any enjoyment from doing so," said Wang.

"And after a few bites, you may stop eating, whereas otherwise you would have scarfed it down."

The team said their findings suggested the brain's complex taste system was made of discrete units "that can be individually isolated, modified or removed."

In a separate study, also published in Nature, scientists said they had boosted health and lifespan in mice by genetically tinkering with autophagy: the process by which cells dispose of harmful waste and unwelcome intruders.

A breakdown of the system is believed to spur ageing and disease.

A team in the United States said they engineered which produced a very active form of a protein that regulates autophagy.

The rodents lived about 12 percent longer.

Other researchers not involved in that study said it was a promising step towards understanding autophagy, but that any extrapolation of the findings to humans, or even other mammals, would be speculative.

Explore further: Rewired taste system reveals how flavors move from tongue to brain

More information: Li Wang et al. The coding of valence and identity in the mammalian taste system, Nature (2018). DOI: 10.1038/s41586-018-0165-4

Related Stories

Rewired taste system reveals how flavors move from tongue to brain

August 9, 2017
By tangling up bitter- and sweet-sensing cells on the tongues of mice, researchers have teased apart how the taste system wires itself. The results, from Howard Hughes Medical Institute (HHMI) Investigator Charles Zuker at ...

Researchers identify a new chemical pathway that helps the brain detect sweet, savory and bitter flavors

January 9, 2018
How do we taste the sugary richness of candy, or the bitter undertones of coffee? What about the savory flavors of smoked and cured meats?

Scientists show how brain circuit generates anxiety

May 29, 2018
Neuroscientists at Cold Spring Harbor Laboratory (CSHL) have identified a neural circuit in the amygdala, the brain's seat of emotion processing, that gives rise to anxiety. Their insight has revealed the critical role of ...

Team deciphers sugar's siren song

January 25, 2016
Sugar's sweetness and calorie content combine to give it lethal power to destroy diets, many scientists have assumed. However, new study by Yale University researchers says the brain responds to taste and calorie counts in ...

Want to eat better? You might be able to train yourself to change your tastes

May 1, 2018
We all love delicious foods, even if we know they may not be good for us. Foods high in energy – specifically sweet, salty and fatty foods – tend to taste the best.

Scientists turn tastes on and off by activating and silencing clusters of brain cells

November 18, 2015
Most people probably think that we perceive the five basic tastes—sweet, sour, salty, bitter and umami (savory)—with our tongue, which then sends signals to our brain "telling" us what we've tasted. However, scientists ...

Recommended for you

Wiring diagram of the brain provides a clearer picture of brain scan data

December 14, 2018
Already affecting more than five million Americans older than 65, Alzheimer's disease is on the rise and expected to impact more than 13 million people by 2050. Over the last three decades, researchers have relied on neuroimaging—brain ...

Scientists identify method to study resilience to pain

December 14, 2018
Scientists at the Yale School of Medicine and Veterans Affairs Connecticut Healthcare System have successfully demonstrated that it is possible to pinpoint genes that contribute to inter-individual differences in pain.

Parents' brain activity 'echoes' their infant's brain activity when they play together

December 13, 2018
When infants are playing with objects, their early attempts to pay attention to things are accompanied by bursts of high-frequency activity in their brain. But what happens when parents play together with them? New research, ...

In the developing brain, scientists find roots of neuropsychiatric diseases

December 13, 2018
The most comprehensive genomic analysis of the human brain ever undertaken has revealed new insights into the changes it undergoes through development, how it varies among individuals, and the roots of neuropsychiatric illnesses ...

Researchers discover abundant source for neuronal cells

December 13, 2018
USC researchers seeking a way to study genetic activity associated with psychiatric disorders have discovered an abundant source of human cells—the nose.

Researchers find the cause of and cure for brain injury associated with gut condition

December 13, 2018
Using a mouse model of necrotizing enterocolitis (NEC)—a potentially fatal condition that causes a premature infant's gut to suddenly die—researchers at Johns Hopkins say they have uncovered the molecular causes of the ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.