Synesthesia Superman
Do you ever wish that you had a super power? What if you could actually taste vanilla when you heard the word “vanilla”. For people with synesthesia this is possible. Synesthesia is a neurological condition resulting in the union of several bodily senses. For instance, a form of synesthesia results in the pairing of certain visual stimuli with colors. Grapheme synesthesia is associated with the pairing of letters, numbers, and other symbols with specific colors. Models proposed by Ramachandran and E.M. Hubbard (2001)account for this phenomenon. A misconnection between V4 (or V8) in the ventral stream of the brain and an area associated with visualizing numbers is hypothesized to result in the condition. To specify, areas V4 and V8 are both located on the underside of the brain. Information about the things we see first enter the occipital lobe in the rear of the brain. Basic information pertaining to orientation of objects takes place here. This information is then relayed to higher processing areas such as V4 and V8. The V4, V8 areas are both associated with complex color perception. Damage to or a misconnection in areas involved in color perception (V4/V8) are likely to result in a synesthesic condition.
In search tests, synesthete subjects rely on their gifted perception to locate certain symbols. The synesthete may physically see the letter “A”, for instance, in the color blue. In a search test there may be only one letter “A” amongst a hundred or so “H’s”. The synesthete can point out the only “A” within seconds as it strongly contrasts with the rest of the letters. As color association is essential in their search for letters, it is proposed that true symbol recognition occurs after synesthesic coupling of colors and symbols takes place. This observation suggests synesthesic coupling in a primary visual area as letter recognition occurs after the color associated with it is perceived. MRI (magnetic resonance imaging) analysis performed by T. Palmeri (2002)shows that higher visual areas are involved in color perception in synesthetes(including areas V4 and V8). These higher regions relay information to the primary visual area of the brain. The evidence provides a model of coupling of color and letters during central visual processing.
Ramachandran and Hubbard (2001) presented visual fields to synesthesic individuals. The fields contained certain numbers that appeared red/ green to the synesthesic subjects, but normal to a control group. Numbers were arranged in such a manner that simple red and green shapes were perceived by the synesthetes. The control group could not see these shapes. This test showed that the synesthetes’ color attribution was perceptually based and not the result of memory. Given that the condition is perceptually based, an error in V4/V8 (areas that emphasize central vision and color) seems plausible.
Posted by AKE
posted by PWH @ 5:34 PM
3 comments
3 Comments:
I think this is a very intriguing topic of discussion. I assume it is rare? Do you have any statistics on it as far as how many people have it? Or when they develop the condition, if at all or if they are just born with it? I'm assuming there is not a ton of research done on this condition but it certainly interesting to see how the brain can function and I wonder how it works. If it is from mutations/evolution standpoint or just a developed thing. I think this would be an interesting condition to have, for a day or so. It seems almost extraterrestrial.
This is really interesting stuff. The brain never ceases to amaze me. I think a little more emphasis should be placed on explaining the actual mechanism of this synesthia. I didn't quite grasp the V2/V4 concept.I got the basic overall concept and loved it, nice job.
The most amusing thing to me about synesthesia is that after more than a decade of research by Ramachandran & Hubbard, et al...published papers almost always conclude with the admission that what they don't know far outweighs what they do know.
Clearly, you researched this topic well but the bottom line is that once the input goes past V1-V2 we can only examine resulting phenomenon by way of disinhibition due to trauma or accident. Whether it is truly crossed wiring or inactive signalling...the idea that some people see blue cats and others eat orange oatmeal is tres cool.
CatherineS
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