While some foodstuffs taste sweet, some are so spicy that we have tears in our eyes. Why is it so? Now, scientists at Howard Hughes Medical Institute and NIH have revealed that 4 basic tastes namely sweet, bitter, salty and umami or savory are apparently coded in specific areas of the brain.
The team disclosed that tastes are sensed by a particular set of neurons in the brains of mice as found in the research. Neurons that show responsiveness to certain tastes seem to be organized separately in something known as a gustotopic map. This is supposedly the first map that presents how taste manifests in the brain of mammals.
“This work~further reveals coding in the taste system via labeled lines, and~it exposes the basic logic for the brain representation of the last~of the classical five senses,” quoted Howard Hughes Medical Institute investigator Charles S. Zuker, who is at Columbia University College of Physicians and Surgeons.
Initially, researchers had calculated the electrical reaction of small clusters of neurons to gauge the region of the mouse’s brain reacting to various tastes. In these trials the different tastes appeared to merge together. Therefore, scientists inferred that neurons seemingly decode all tastes in a broad manner. The scientists first uncovered a ‘one taste, one cell class’ coding scheme. When these receptor cells were activated, it spurred inborn responsiveness in mice such as affinity towards sweet, dislike towards bitter and so on.
There was an apparent relation between taste and innate influences, but the scientists were unclear as to why many tastes are processed by the same neurons in the brain. They therefore developed a new technique called two-photon calcium imaging which helped them locate the parts of the brain showing responses when exposed to different tastes.
The scientists observed that when mice received something bitter to taste, many neurons in a specific area supposedly lit up. Alternatively when they were given something salty to taste an area covering a smaller portion seemed to start working. Every taste has a respective hotspot in the brain. There appeared to be no overlapping and there were gaps between them. As per the scientists, there is no preexisting set for taste while it reaches the brain. Also, the receptors for all tastes are present throughout the tongue in a random way.
Therefore, this spacial arrangement of taste neurons in the form of a topographic brain map looks surprising. Zuker and his team conclude that they now have plans to find out other aspects of taste like olfaction, texture, hunger and expectations.
The research is published in the journal Science.