The gustatory cortex interprets the incoming signals and integrates them with other sensory information, such as smells, allowing us to perceive flavors, Munger says. Our thoughts and memories also play a role in taste perception. In other words, our sense of taste is much more complex than the tongue map would have us believe. She writes about science, technology, and culture.
Munger, S. The taste map of the tongue you learned in school is all wrong. Monell Chemical Senses Center. Monell taste primer. Informed Health Online [Internet]. How does our sense of taste work? See how discoveries in the lab have improved human health. They presumably like it because of the fat, or maybe the amino acid umami component of it.
To learn more about the delectable science of taste, check out our video with Margolskee above. You learned very wrong. When sweet, bitter, sour, salty, or savory substances reach the surface of taste buds, they are recognized by their own respective taste receptors.
Taste receptors give a signal to the taste cells, and the taste cells pass this signal through nerves to the brain. This combination of signals allows us to experience different tastes from different foods [ 1 ]. Our sense of taste enables us to enjoy the food we eat. But we usually do not like the bitter taste, and neither does the rest of the animal kingdom.
Most animals reject things with a bitter taste, because toxic substances usually taste bitter. This natural rejection of bitter tastes has developed in animals from fish to humans, to prevent us from eating harmful foods. These days, we know that not all bitter-tasting things are harmful.
Some bitter-tasting things can be even good for our health, such as green tea, cacao the seeds used to make chocolate , and some drugs used to cure diseases. A lot of things in nature taste bitter. Therefore, it is not surprising that many different kinds of bitter taste receptors exist. There are 25 kinds of bitter taste receptors in humans, compared with 35 in mice. The ability of some bitter taste receptors to recognize bitter substances differs.
Some of these receptors can recognize various types of bitter substances. Others can only recognize a few specific bitter substances [ 2 ]. Researchers are interested in learning more about the function of bitter taste receptors.
Which bitter substances can be recognized by individual bitter taste receptors? Do the actions of the bitter taste receptors play a role in our health? As we have mentioned, our ability to sense a bitter taste is a protection against harmful things.
Can other parts of the body, besides the tongue, also sense bitter substances? We wanted to look for bitter taste receptors throughout the body. But bitter taste receptors are specific proteins that are hard to detect and visualize. So, we decided to look for cells that have bitter taste receptors on them, because cells are easier to see under the microscope. To visualize these bitter taste receptors, we made something called a reporter mouse.
A reporter mouse is an animal model used to detect proteins of interest. As shown in Figure 1 , we introduced a green fluorescent protein GFP into the cells of these mice. The cells will only glow green if they have the bitter taste receptors that we are looking for.
In fact, it was debunked by chemosensory scientists the folks who study how organs, like the tongue, respond to chemical stimuli long ago.
The receptors that pick up these tastes are actually distributed all over. And yet you probably saw the map in school when you learned about taste. So where did it come from? It is true that the tip and edges of the tongue are particularly sensitive to tastes, as these areas contain many tiny sensory organs called taste buds. Different parts of the tongue do have a lower threshold for perceiving certain tastes, but these differences are rather minute.
The graph plots the relative change in sensitivity for each taste from one point to the next, not against other tastes. It was more of an artistic interpretation of his measurements than an accurate representation of them. And that made it look as though different parts of the tongue were responsible for different tastes, rather than showing that some parts of the tongue were slightly more sensitive to certain tastes than others.
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