The commonly used map of the tongue, showing the 4 tastes is wrong and creates a bad idea of how taste work. As noted in The Tongue Map: Tasteless Myth Debunked, there is not much known about the sense of taste, a lot more information have been gathered on hearing and vision. It may be due to the fact that this sense is apparently not primordial for survival. It is indeed more important that it may seems as allows us to detect spoiled and unripe food.
Of course, in modern society, it is far less useful in day to day life than vision or hearing.
There are 5 different tastes identified:
And some are wondering if there may be sixth kind of receptor for the fat.
Umami is the least known one, it is very common in Japanese cuisine, and can be tasted through the receptors for glutamate. It is said to be a lasting one, that will let you with an delicious aftertaste. From the Wikipedia article:
Umami has a mild but lasting aftertaste that is difficult to describe. It induces salivation and a sensation of furriness on the tongue, stimulating the throat, the roof and the back of the mouth.
That rises a new important point, we always associate taste with the tongue, but in fact, taste buds are present on more places:
- soft palate
- upper esophagus
This taste buds contains the taste receptors that will react to the chemical component we associate with a given taste, and transmit the information to the brain.
Last, but not least, the smell is tightly tied to taste, we all know when we have a cold taste changes, and can sometimes feel like gone. Both smell and taste are analyzing the chemical compounds of what we smell and eat.
You can read more about taste and smell ties at BrainFacts.