Synesthesia—combined experience of two senses

Synesthesia is a neurological condition whereby two or more senses are mingled due to some cross wiring in brain. The five senses that are usually experienced separately might be jointly experienced .For example somebody may see color when they read words so hereby people may experience “C” as red and “B” as green. Likewise all the five senses may be experienced in any combination.

Synesthesia is not a disease or illness; it is just a curious condition in people who could experience any two senses jointly. In one common form of synesthesia called grapheme-color synesthesia individuals associate colors with numbers. Devin Terhune and his colleagues at the University of Oxford conducted a study to find the causes of synesthesia.

The team started with transmitting transcranial magnetic stimulation to the area of brain called primary visual cortex. This was done to evoke phosphenes—tiny flashes seen after gazing at light directly. It was observed that the synesthetes (those who experience synesthesia) needed one third of the stimulation to evoke phosphenes than others who did not experience synesthesia. It was concluded that the requirement of less stimulation was due to higher than normal baseline activity of neurons in primary visual cortex.

As synesthesia tends to be genetically passed condition so people may be predisposed to hyperactive neurons at their birth-Terhune suggests. He also thinks that hyper activation of neurons may cause them to develop connections between areas of brain that are not normally paired.

Other things like creativity, metaphorical thinking and linking between seemingly unrelated ideas is also thought to be the linked to synesthesia.