Neuroscientists have discovered how to manipulate the brain’s underlying sugar cravings, and how to make them off-putting.
Researchers from Columbia University’s Zuckerman Institute announced on Wednesday they had identified two specific regions in the brain that respond to sweet and bitter taste, and altered those responses in mice.
The study published in Nature found the desire can be erased by manipulating neurons in the amygdala, the emotion centre of the brain.
The findings point to new strategies and treatments to address eating disorders including obesity and anorexia nervosa, researchers say.
“The very concept of sweet, the very word sweet, implies this goodness, this reward, this craving that we link to it. And similarly bitter on the other side has an immediate meaning to it. So we wanted to know, how does the brain encode meaning on sensory experience?” Columbia University’s Zuckerman Institute lead author Dr Charles Zuker said.
“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.”
The work, while yet to be tested in humans, is promising according to researchers, as the amygdala almond-sized organs in the temporal lobe too play a role in emotions like fear and pleasure, as well as survival instinct and unconscious reactions.
The amygdala also directly connects to the taste cortex of the brain but was left untouched.
The research involved using laser light stimulation to artificially turn on the neuron connections, making the mice 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.
During the experiment the mice could still recognise and distinguish sweet from bitter, but now lacked the basic emotional reactions or preference for sugar.
“It would be like taking a bite of your favourite chocolate cake but not deriving any enjoyment from doing so,” study co-author Dr Li Wang.
“After a few bites, you may stop eating, whereas otherwise you would have scoffed it down.”
The team is doing further research into additional brain regions that serve critical roles in the taste system.
“Our goal is to piece together how those regions add meaning and context to taste,” Dr Wang said.
“We hope our investigations will help to decipher how the brain processes sensory information and brings richness to our sensory experiences.”