Source:Columbia University Medical Center
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 have turned this idea on its head, demonstrating in mice the ability to change the way something tastes by manipulating groups of cells in the brain.
The findings were published today in the online edition of Nature.
“Taste, the way you and I think of it, is ultimately in the brain,” said study leader Charles S. Zuker, PhD, professor of biochemistry and molecular biophysics and of neuroscience, a member of the Kavli Institute for Brain Science and the Mortimer B. Zuckerman Mind Brain Behavior Institute, and a Howard Hughes Medical Institute Investigator at Columbia University Medical Center (CUMC). “Dedicated taste receptors in the tongue detect sweet or bitter and so on, but it’s the brain that affords meaning to these chemicals.”
The primary aim of Dr. Zuker’s lab is to understand how the brain transforms detection of chemical stimuli into perception. Over the past decade or so, Dr. Zuker and his colleagues proved that there are dedicated receptors for each taste on the tongue, and that each class of receptor sends a specific signal to the brain. More recently, they demonstrated that each taste is sensed by unique sets of brain cells, located in separate locations in the brain’s cortex -generating a map of taste qualities in the brain.
The scientists used optogenetics, which allowed them to directly activate specific neurons with laser light. Yueqing Peng, a postdoctoral associate in Dr. Zuker’s lab, examined whether manipulating the neurons in these brain regions could evoke the perception of sweet or bitter, without the mouse actually tasting either. (Sweet and bitter tastes were chosen because they are most critical and recognizable tastes for humans and other animals. Sweet taste permits the identification of energy-rich nutrients, while bitter warns against the intake of potentially noxious chemicals).
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