Deaf people have heightened abilities in the remaining senses, say researchers.
Researchers at the University of Western Ontario, led by Stephen Lomber of the Centre for Brain and Mind, have discovered there is a causal link between enhanced visual abilities and reorganization of the part of the brain that usually handles auditory input in congenitally deaf cats.
Using congenitally deaf cats and hearing cats, Lomber and his team showed that only two specific visual abilities are enhanced in the deaf: visual localization in the peripheral field and visual motion detection.
They found the part of the auditory cortex that would normally pick up peripheral sound enhanced peripheral vision, leading the researchers to conclude the function stays the same but switches from auditory to visual.
"The brain is very efficient, and doesn't let unused space go to waste," Lomber said.
"The brain wants to compensate for the lost sense with enhancements that are beneficial. For example, if you're deaf, you would benefit by seeing a car coming far off in your peripheral vision, because you can't hear that car approaching from the side; the same with being able to more accurately detect how fast something is moving," he said.
Lomber and his team are trying to discover how a deaf brain differs from a hearing brain to better understand how the brain handles cochlear implants.
If the brain has rewired itself to compensate for the loss of hearing, what happens when hearing is restored?
"The analogy I use is, if you weren't using your cottage and lent it to a friend. That friend gets comfortable, maybe rearranges the furniture, and settles in. They may not want to leave just because you've come back," explained Lomber.
The findings were published in the journal Nature Neuroscience.