How your tongue tells your brain what you’re tasting

Contrary to what you may have learned in school, different areas of the tongue don’t detect different flavors—instead, each taste bud has all five taste receptors built in.
Contrary to what you may have learned in school, different areas of the tongue don’t detect different flavors—instead, each taste bud has all five taste receptors built in.

From a nutty, aged cheese to the floral finish of dark chocolate, delicious tastes perpetually bombard our tongues. Here’s how a tongue takes these flavors from the plate to the mind.

The tongue contains three types of taste-sensing papillae.
The tongue contains three types of taste-sensing papillae.

The tongue, which anchors the body’s system of taste, is a piece of muscular flesh covered in a mucous membrane. To the human eye, our tongues appear dotted with tiny bumps called papillae. Often mistaken for taste buds themselves, these bulb-like dots actually contain groups of taste buds.

Three types of taste-sensing papillae dot the tongue. Fungiform papillae, concentrated mostly at the tip and sides of the muscle, usually contain one taste bud on their mushroom-shaped tips. Foliate papillae, arranged into reddish folds on the sides of the tongue, contain many taste buds organized around these crevices. Larger, dome-shaped vallate papillae sit toward the back of the tongue and, like foliate papillae, can house as many as 250 taste buds each.

A fourth type—filiform papillae—is the smallest and most numerous on the tongue. This type contains fine hairs that connect to nerves associated with touch, allowing you to feel the texture of what you’re eating, but they don’t contain any taste buds.

While these different types of papillae vary in structure, they typically organize taste buds around crevices, which collect broken-down food chemicals released when you chew. These crevices also house glands that secrete saliva.

Taste buds are complex little growths, too. Each one contains a collection of between 50 and 150 taste receptors and supporting cells, all nested together like cloves in a bulb of garlic. While each person’s taste bud count varies, humans tend to have between 2,000 and 5,000.

Each taste receptor is specialized to detect one of five flavor types: sweet, sour, bitter, salty, or umami. Contrary to what you may have learned in school, different areas of the tongue don’t detect different flavors—instead, each taste bud has all five taste receptors built in. Each receptor has small hair-like proteins called microvilli, which bind to specific chemical compounds corresponding to the flavor type it specializes in—and scientists are still figuring out how chemicals fit into the receptors. Deeper into the tongue’s flesh, these cells attach to nerves specifically involved in taste, which connect them to the rest of the nervous system.

1. The Breakdown: As you eat, your mouth breaks food down into its chemical building blocks. Your teeth physically chop and break larger components, and saliva contains various enzymes that digest crumbs into molecules.
1. The Breakdown: As you eat, your mouth breaks food down into its chemical building blocks. Your teeth physically chop and break larger components, and saliva contains various enzymes that digest crumbs into molecules.

2. Chemical Attraction: Once these basic food chemicals begin floating around the tongue, they wash over the papillae, filling into crevices to reach the taste buds. The taste receptors’ microvilli only interact with specific chemicals that correspond with their taste specialization. Sugars trigger sweet receptors, acids trigger sour receptors, minerals like sodium chloride and magnesium trigger salt receptors, a group of about 35 proteins trigger bitter receptors, and glutamic and aspartic acids trigger umami.
2. Chemical Attraction: Once these basic food chemicals begin floating around the tongue, they wash over the papillae, filling into crevices to reach the taste buds. The taste receptors’ microvilli only interact with specific chemicals that correspond with their taste specialization. Sugars trigger sweet receptors, acids trigger sour receptors, minerals like sodium chloride and magnesium trigger salt receptors, a group of about 35 proteins trigger bitter receptors, and glutamic and aspartic acids trigger umami.

3. Sending Signals: Once they bind to a food chemical, taste receptor cells activate their individual nerves. These shoot sharp electrical signals to the brain to tell our noggins that those flavors are present on the tongue. Eventually, they level off as the receptor cells get used to the taste and the brain has interpreted it properly.
3. Sending Signals: Once they bind to a food chemical, taste receptor cells activate their individual nerves. These shoot sharp electrical signals to the brain to tell our noggins that those flavors are present on the tongue. Eventually, they level off as the receptor cells get used to the taste and the brain has interpreted it properly.

4. The Nose Knows: Gaseous food chemicals released from chewing travel through the back of the mouth and into the nasal cavity. Here, olfactory sensors detect more complex flavor profiles beyond the five coded for by taste buds and send them to the brain.
4. The Nose Knows: Gaseous food chemicals released from chewing travel through the back of the mouth and into the nasal cavity. Here, olfactory sensors detect more complex flavor profiles beyond the five coded for by taste buds and send them to the brain.

5. Information Highway: The taste receptor signals, along with other sensory nerve flares like pain, temperature, and touch, reach the lower brain stem. From there, they enter the conscious brain bundled together.
5. Information Highway: The taste receptor signals, along with other sensory nerve flares like pain, temperature, and touch, reach the lower brain stem. From there, they enter the conscious brain bundled together.

6. I Think I Like It: Once the beefed up taste signals reach areas of sensory perception in the brain, they combine with smell signals to tell the brain what’s in the mouth. If it perceives the overall taste as pleasant, the brain will trigger the increased production of saliva and gastric juices, aiding in digestion and making the meal even more mouthwatering.
6. I Think I Like It: Once the beefed up taste signals reach areas of sensory perception in the brain, they combine with smell signals to tell the brain what’s in the mouth. If it perceives the overall taste as pleasant, the brain will trigger the increased production of saliva and gastric juices, aiding in digestion and making the meal even more mouthwatering.

Source: popsci
How your tongue tells your brain what you’re tasting