Due to years of movies (particularly kung fu movies or superhero movies), misconceptions about blindness abound. For example, for many years people believed that those with blindness “train” themselves to better use their other senses.
However, research released in September of 2017 shows that our brains naturally re-map areas that go unused—in effect, our brains rewire themselves to accommodate the loss of our senses.
Our Brains Are In a Constant State of Change
“Brain plasticity” is the research term for our brain’s ability to adapt to changing sensory input. It just means it adapts to our ability to interpret and interact with the world. Earlier studies used magnetic resonance imaging (MRI) and fMRI to record data in the blind. Another prior study analyzed plasticity in the deaf.
Both study sets showed that when we lose sensory input (i.e. lose the ability to hear or see), areas of the brain normally devoted to visual or auditory processing will be reallocated for other uses. Imagine that a room in your home that once belonged to a roommate is now no longer in use—what your brain does is take that empty room and use it for something else.
It’s a testament not only to our resilience, but to the incredible efficiency of the human body.
The study released in September used a tool that records the brain’s production of magnetic fields. This shows the differences in the brain’s activity and where the activity takes place. Researchers mapped the brain activity of both blind and sighted people when playing three audio recordings.
Although both groups used the area of the brain normally devoted to auditory processing, the blind participants also used the area of the brain normally devoted to visual processing. In fact, when an intelligibile recording was played, in the blind participant’s brains, the imaging indicated their neurons fired in sync with the speech.
This suggest that when we lose the ability to see, the brain takes our “empty space” and repurposes it for additional processing for hearing or touch or taste (or whatever your brain wants to use it for). This phenomenon may have led to the belief that the blind have better senses than people with sight—their brains are devoting more processing power to other senses.
Future research questions include the limits of remapping and whether it extends to the brain’s “architecture,” or formation. Another study reveals early blindness may affect the brain’s architecture.
Multimodal MRI Mapping
The lead author of the 2018 study published in PLOS ONE, Corinna Bauer, scientist at Schepens Eye Research Institute of Mass. Eye and Ear, says its study used multimodal MRI scans to map a full brain picture. It included a total of 28 participants, 12 of whom were born blind or went blind by age three and 16 of whom were sighted. All participants were of similar age, societally integrated and capable of independent living.
The test results revealed “architectural” and functional changes in the brains of the blind participants. These included an increase in cortical volume and “enhanced white matter connections.”
Further studies will explore potential brain changes in those who become blind later in life. Additional studies will test the same hypothesis to determine if similar results occur. Further study of the changes in brain activity could lead to new treatments for blindness and new teaching methods for the blind.