Why is the sweetness getting dull?... The secret of the tongue has been revealed.

[Anchor]
When I eat sweet food, I feel an intense sweetness at first and then I feel weaker over time.Korean researchers have found that cells in the tongue of

communicate with each other to control sensitivity.

I'm reporter Jang A-young.

It's a sweet candy.When I put it in my mouth

, it feels really sweet, but even after a little while, I can't feel the first strong sweetness.

[Reporter]
This phenomenon is called 'sensory adaptation'.

When you go to a dark place, your eyes are dark at first, but just as the iris controls the light and you can see it in the dark, the information on the taste that lasts for the tongue is designed to be reduced.

Our bodies have evolved to focus more on new stimuli or risks than on persistent sensations.

The number of cells per taste buds is about 100.

Of these, about half of the cells taste, and the other half, 'taste glial cells', were considered to play no role because they did not have taste receptors.

However, when I directly spilled the sweetness on the tongue of a living mouse, a new fact was confirmed.

Taste cells, which were considered mere spectators, were actively helping taste cells (taste receptors) adapt to sweetness.

[Park Ga-yeon / Seoul National University's Ph.D. course: Taste receptors react and release certain substances, and taste glial cells have receptors for those substances. I was able to see it because it was alive....]

Even with the same sweetness, the sensitivity of the taste was different depending on the ingredients, but sugar had a longer sweetness duration than the sweetener used in diet coke.

[Choi Myung-hwan / Seoul National University Vice Professor of Life Sciences: I hope we can understand the taste quantitatively. It's the first step, tongue. I thought it would be simple before, but the more we study, the more complicated information processing is happening....]

The researchers said that the same "taste adaptation" occurs not only in sweetness but also in bitterness, salty, sour and umami, and that they plan to study the process of transmitting each taste to the brain.

I'm YTN's Jang Ayoung.