When your alarm clock goes off in the morning, your auditory cortex processes that sound. When you walk past the café on your way into work you can smell the coffee, which is processed by your olfactory cortex.
What we see is processed by our visual cortex. But since 1996, it has been known that if the visual cortex cannot be used because a person is blind, it can be used for a non-visual function such as reading braille.
This discovery led to further studies to determine whether brain regions can take over functions they were not genetically predetermined to perform. A new study from MIT has investigated whether our visual cortex can change its function to include language processing.
Our brain has two areas dedicated to allow us to process and understand language: Broca’s area and Wernicke’s area.
These areas are highly specialised and have particular properties including a specific internal arrangement of their cells and special connectivity with other parts of the brain. It had been thought that because of these specialised properties, other areas of the brain would be unlikely to be involved in language processing.
However this new study showed that in blind people a part of the visual cortex can indeed becomes involved in language processing. It doesn’t replace the other specialised areas, but works as an “add on”. This makes sense as it allows the brain to usefully use that portion of the brain which it can’t use for it’s normal function and is a wonderful example of neuroplasticity at work
It seems that our clever brain can use a degree of flexibility for what it does, beyond our genetic programing.
In the study they used fMRI in subjects who had been blind from birth. When they were given tasks of sentence comprehension the brain scans showed brain activity in their visual cortex as well as Broca’s and Wernicke’s areas.
So in a nutshell, what does this mean?
It adds to our understanding of how the brain constantly adapts and rewires itself in response to sensory input and our environment.
One of the author’s of the study Marina Bedny put it beautifully when she said, “Your brain is not pre-packaged. It doesn’t develop along a fixed trajectory, but rather is a self building toolkit”.
Marina Bedny, Alvaro Pascual-Leone, David Dodell-Feder, Evelina Fedorenko and Rebecca Saxe. Language processing in the occipital cortex of congenitally blind adults. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1014818108