Blindness & Brains
How does blindess affect brain stucture?
Bio-Chemical/ Neural Psychology
People that are blind have no sight and cannot physically see anything. However, depending on the age a person goes blind can affect the way the person's brain develops as well as their brain structure (University of California, 2009). People that are blind rely on other senses such as hearing and touch to replace their lack of vision.
Individuals that were born blind differ immensely from those that are not blind at all in am area of the brain's corpus callosum that assists in the transmission of visual information between the hemispheres in the brain (University of California, 2009). It is believed that the cause of this is the reduced amount of myelination from the absence of visual input. When blindness occurs in adolescence, myelin is already almost complete therefore the structure of the corpus callosum may not be very influenced by the visual input loss (University of California, 2009).
How does the brain differ?
Individuals that are blind show enlargement in the areas of the brain other than the area that is responsible for vision. An example is the increased size in the frontal lobes. One of the things involved in the frontal lobes is working memory, which was found to be abnormally enlarged (University of California, 2009). Those that are not blind have "normal" size parts of the brain. Because of this their senses are relative the same. The myelin in their brain develops over the years which is what helps with the visual aspect of development. This is located in the midbrain, which is also involved in hearing as well as vision (Cognitive Psychology, 2009). Children that have the ability to see learn through vision and hearing whereas blind children learn through hearing. Therefore activity in babies and children is limited because the environment is unknown and sound seems to be coming from nowhere (Cognitive Psychology, 2009).
One question that is asked is the reasoning as to why the visual cortex would be recruited for language processing when the language processing areas of those that are blind functions normally. "According to Bedny, it may be the result of a natural redistribution of tasks during brain development" (Massachusetts Institute of Technology, 2011, para. 12). Different parts of the visual cortex are divided up for different functions during development.
Cognitive Psychology. (2009). Brain and cognition: brain structure. Retrieved from http://cognitivepsychology.wikidot.com/cognition:brain-structure
Massachusetts Institute of Technology. (2011). Parts of brain can switch functions: In people born blind, brain regions that usually process vision can tackle language. ScienceDaily. Retrieved from www.sciencedaily.com/releases/2011/02/110228163143.htm
University of California - Los Angeles. (2009). Blindness causes structural brain changes, implying brain can re-organize itself to adapt. ScienceDaily. Retrieved from www.sciencedaily.com/releases/2009/11/091118143259.htm