2012-02-20 15:21:02
Why do our senses provide us with sensations of a certain quality, and not another?
Sometimes, we have certain aspects of the world so assumed that it is difficult for us to ask ourselves why they are like this and not otherwise. Among them are our senses. Few have ever asked themselves why we perceive sounds as such, and not as colors, for example, or why we perceive colors that way, and not as smells, or as sounds. In other words, why do our senses provide us with personal sensations of a certain quality, and not another? The reason for this probably lies in the fact that, throughout the evolution of our nervous system and our senses, it has been more effective to encode sensations from sight, hearing, smell… in different ways. The different coding of the information that the senses capture from the outside world has given a particular character to each of them (colors, smells, sounds, pain, heat…). This allows us to distinguish them clearly, in addition to experiencing them in a personal and non-transferable way, which has favored our survival in competition with other species.
SENSORY RARITY
Some people, however, suffer from “mixed senses” to a greater or lesser extent. This means that a certain perception induces in them an anomalous sensation of another or the same sense. For example, some sounds can induce a sensation of taste or color when heard. For these people, sounds also communicate, therefore, flavors or colors. Other people see numbers and letters in color, that is, the number 6 is always green, and 8 is orange, for example, regardless of the color in which they are written. They also see each letter of a certain color, always. This curious property, which does not usually cause major problems for those who possess it, is called synesthesia, a word derived from the Greek words sin (together), and aisthesis (sensation). Synesthesia is not as uncommon as it might seem, as it is experienced by between 2% and 4% of the human population. And there are many more strange people out there than we are willing to admit, perhaps because, being all strange in one way or another, we insist on believing that we are normal. Some types of synesthesia are even more curious than those described above. In sequential-spatial synesthesia, the numbers of the years, months, or days of the week induce a spatial sensation and individuals with this condition perceive them as if they were located in a precise space, as if they were books arranged in a shelf. Another type of synesthesia, recently described, generates a sound in response to a visual stimulus. Seeing a vehicle’s turn signal on, for example, can also induce a sensation of sound. This sound sensation can vary with the frequency of the flashing or with its type or color.
In total, to date, more than sixty types of synesthesia have been described, although only a few have been scientifically investigated. In any case, research has made it clear that, within a type of synesthesia, synesthetic perceptions vary in intensity, and that a person can experience not just one, but two or more synesthetic perceptions. Likewise, it has been proven that people also vary in the degree of awareness of their synesthetic perceptions.
FAMILY SYNESTHESIA
Research on this curious condition has also revealed that people with synesthesia tend to group together in families, many of whose members share this characteristic, although they do not necessarily experience the same type of synesthesia. However, it is also possible to experience synesthetic sensations when taking psychedelic drugs, which alter perceptions, or when suffering an epileptic seizure. This means that the normal brain structure allows the mixing of the senses, although under normal conditions it is prevented by some mechanism, still unknown today.
Possibly, therefore, individuals with synesthesia have this mechanism weakened due to some gene variant that their family members have also inherited, which generates this condition. The search for the gene or genes responsible for synesthesia has intensified in recent years, thanks to modern molecular biology and genetic technologies. However, these efforts have not yet borne the expected fruit. A recent study led by neurologist David Eagleman of the Baylor College of Medicine, in Houston, USA, has identified a region on chromosome 16 that possibly houses the gene responsible for the most common form of synesthesia: the one that associates a color with each letter or number. Studies continue to identify the gene responsible, but this has not yet been achieved.
The discovery of even a single gene involved in synesthesia would allow us to begin to reveal the causes of this condition, but it would also provide valuable information about the mechanisms that act in the brain to encode our sensations, to differentiate them from one another, and about the intriguing possibility that these gene variants are associated with certain personality characteristics of individuals with synesthesia, such as greater appreciation of art or greater creativity. Without a doubt, the human brain still contains many mysteries, but as someone very correctly said: if we had a brain so simple that we could easily understand it, we would be so stupid that we would not be able to understand it.
WORKS BY JORGE LABORDA.
One Moon, one civilization. Why the Moon tells us that we are alone in the Universe
One Moon one civilization why the Moon tells us we are alone in the universe
The intelligence funnel and other essays
The thousand and one bases of DNA and other scientific stories
#Cienciaes.com #search #synesthesia #genes