Commonness & Misconception
The commonness of synesthesia can range anywhere from 1 in 100,000 to as little as 1 in 2,000 people. A common misconception is that synesthesia is a mental illness, however, that is not the case. It can be passed down from generation to generation genetically.
What occurs in the brain?
All areas involved in color visual processing are collectively called visual area 4 (V4), a region located in the fusiform gyrus in the temporal lobe. The V4 is extremely close to another region of the brain, within the fusiform gyrus, that deals with the physical form of numbers. Other areas involved in visual processing are the
V1, V2, V3, and V5/MT.
Many behavioral studies conducted involve the scanning of the brain through fMRI machines. These studies show the activation of V2 and V4 when patients with Chromesthesia (generally V4 and V5 for Grapheme-Color synesthesia) were exposed to auditory stimuli. So, it can be seen that across several studies, V4 is seen as the dominant region. Furthermore, synesthetes tend to show greater volumes of areas of grey or white matter within certain areas, which reinforces the general trend that the brains of synesthetes have structural differences in certain areas.
V1, V2, V3, and V5/MT.
Many behavioral studies conducted involve the scanning of the brain through fMRI machines. These studies show the activation of V2 and V4 when patients with Chromesthesia (generally V4 and V5 for Grapheme-Color synesthesia) were exposed to auditory stimuli. So, it can be seen that across several studies, V4 is seen as the dominant region. Furthermore, synesthetes tend to show greater volumes of areas of grey or white matter within certain areas, which reinforces the general trend that the brains of synesthetes have structural differences in certain areas.
Types of Synesthesia
There are several types of synesthesia, but for the sake of this project, we will only be discussing three: Grapheme-Color Synesthesia, Chromesthesia, and Ordinal Linguistic Personification.