Later On

A blog written for those whose interests more or less match mine.

The neurophysiology of synaesthesia

with one comment

Synaesthesia (conflating senses—the punch line of an old scifi story in which a blow to the head caused synaesthesia in the protagonist, leading to an operation to correct the problem, was that he recovered from the anesthesia and said, “What smells purple?”) seems to be a lot more common than was originally thought.
This post explains the neuropsychology of synaesthesia. It begins:

In the 1880s, Francis Galton described a condition in which “persons…almost invariably think of numerals in visual imagery.” This “peculiar habit of mind” is today called synaesthesia, and Galton’s description clearly defines this condition as one in which stimuli of one sensory modality elicit sensations in another of the senses.

There are several different kinds of synaesthesia, and the condition is now known to be far more common than was previously thought. Galton was describing a specific type of synaesthesia, called grapheme-colour synaesthesia, in which printed numbers or letters elicit the sensation of specific colours. The Nobel Prize-winning physicist Richard Feynman, who reported seeing equations in colour, was a grapheme-colour synaesthete, while the expressionist artist Wassily Kandinsky, in whom musical tones elicited specific colours, was a tone-colour synaesthete. Kandinsky used his synaesthesia to inform the artisitic process – he tried to capture on canvass the visual equivalent of a symphony. There is also a type of synaesthesia called mirror-touch synaesthesia, which was discovered only very recently (see below).

There are a number of theories which seek to explain synaesthesia in terms of neurobiological mechanisms. One of them holds that synaesthetes have unusual connections between different sensory regions of the cerebral cortex, perhaps because a failure to prune improper, under-used or redundant synaptic connections during development of the nervous system. Thus, stimuli entering one sensory system will generate activity in another sensory system, and activity in the latter system will also evoke sensations in the synaesthete, despite an absence of the appropriate stimuli for that modality.

According to the other, …

Continue reading.

Written by Leisureguy

5 September 2007 at 1:23 pm

Posted in Daily life, Science

One Response

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  1. Some books on synesthesia: “Blue Cats and chartreuse Kittens: How synesthetes color their worlds” (Henry Holt & Company 2001)
    “The Mind of a Mnemonist”


    Praise Mbeka

    6 September 2007 at 4:54 am

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