“A taste bud is like a mini-brain,” says DU neurobiologist John Kinnamon. Photo: Wayne Armstrong
Remember those colorful diagrams that showed how different regions of the tongue contained different types of taste buds that detected specific tastes, like salty, sweet and bitter? Many people do, because this commonly held misconception — which came about when a German study on taste was mistranslated — is all most people know about our sense of taste. As it turns out, scientists don’t know much either.
Taste, or gustation, used to be considered a very simple system, one that could easily be understood with the help of rudimentary diagrams like tongue region maps. In reality, however, taste is the most complex of the five senses, and the least understood, according to John Kinnamon, a neurobiologist and professor of biological sciences at DU.
“Most all the senses utilize a single biochemical transduction pathway,” Kinnamon explains. “The sense of taste is unique in that it utilizes a diversity of biochemical transduction pathways.”
And while research conducted in the last decade has led to a greater understanding of the initial events involved in sensory transduction, little is known about the contacts between taste buds and nerve fibers.
Kinnamon began studying taste more than 20 years ago as a postdoctoral researcher at the University of Colorado School of Medicine.
“As a neurobiologist my passion has always been the synapse, the functional contact between nerve cells. I was amazed that there was so little research on taste, compared with the wealth of studies on vision, hearing and touch,” Kinnamon says.
For the past six years — armed with a $1.6 million grant from the National Institutes of Health — he has focused on elucidating how the cells in taste buds communicate with one another and with the brain.
Each taste bud contains between 50 and 100 epithelial cells, like those found in the skin. Kinnamon’s research, however, has demonstrated that the epithelial cells found in taste buds function like neurons by using the same proteins as those found in synapses in the nervous system. A better understanding of taste buds, he says, could lead to a better understanding of the brain.
“A taste bud is like a mini-brain,” Kinnamon says. “It receives input from the external environment, makes decisions, and then sends output to other parts of the nervous system. And it’s a whole lot easier to study a taste bud than a brain.”
Aside from providing a nice model for the brain, Kinnamon’s research into the gustatory system will provide important information about one of humankind’s primal biological functions.
“How an animal can take in the multitude of sensory input it receives and then make appropriate decisions is essential to its survival and the survival of the species,” Kinnamon says. “Understanding how taste works in both health and disease will make it possible to treat patients and the elderly who have problems with their sense of taste.”
And considering that taste disorders can be a risk factor for heart disease, diabetes, stroke and other health issues that require a strict diet, according to the National Institutes of Health, Kinnamon’s research could also make it possible for people to live longer, healthier lives.
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