A long-standing mystery has concerned how our taste buds inform our brain of what we are tasting. New findings published by Miller School researchers in The Journal of Neuroscience help solve the matter. Simply put, it seems the cells in each of our taste buds communicate with each other to send final messages to the brain.

“Our taste buds regulate what we eat, how much we eat, and they act as an early warning system if we are about to ingest something that could be dangerous to us,” says Stephen D. Roper, Ph.D., professor of physiology and biophysics and senior author of the study.

There are 5,000 to 10,000 taste buds in the mouth, and each of those taste buds has about 100 individual taste receptor cells. Our taste buds are tuned to recognize sweet, bitter, salty, sour, and, as recently discovered, also a fifth taste called umami. Umami detects amino acids, such as glutamate, which are found in protein-rich foods and give them a savory taste. Monosodium glutamate, a natural substance found in meats and cheeses and often used as an additive in Chinese cooking, is an example of a umami taste.

“A question has always been, ‘Are taste buds and their cells each tuned to only one of the basic tastes, or can individual cells respond to multiple tastes?’” says Roper.

There are two classes of taste bud cells directly involved in sending signals about taste: receptor (type II) cells that detect sweet, bitter, and umami taste stimuli, and presynaptic (type III) cells, which respond to all taste stimulation.

Seth Tomchik, Ph.D., a post-doctoral associate and lead author of the study, along with the other researchers used novel transgenic mice to test taste­­‑cell responses. The mice were genetically engineered to display a green fluorescent protein in certain types of taste cells so they could be detected with a microscope.

“We found how the different types of cells in the taste bud cooperate and communicate to generate meaningful signals to send to the brain,” says Roper. “Some of the taste cells function very narrowly by only recognizing certain tastes, while other cells sense different tastes. When the two types of cells communicate with each other there is an even broader response overall to different tastes.”