People deaf from birth may develop a form of ‘super-vision’ that helps them spot and track moving objects, research has shown.
Scientists believe the brain adapts to the loss of hearing by rewiring itself to compensate through sight.
Parts of the brain that normally locate sound sources learn to do the same job using vision instead.
Researchers made the discovery by studying cats – the only animal besides humans that can be born congenitally deaf.
People who are born deaf or blind often report their remaining senses being enhanced.
Some experts believe that losing one sense early in life at a time when nerve connections are still being made allows the brain to rewire itself to compensate.
In deaf cats, scientists found brain regions that usually handle input from hearing become re-organised.
Areas of the brain’s auditory cortex that would normally pick up peripheral sound boosted peripheral vision.
As a result, deaf cats – and probably humans who are born deaf too – have an enhanced ability to observe moving objects.
Study leader Dr Stephen Lomber, from the Centre for Brain and Mind at the University of Western Ontario, Canada, said: ‘The brain is very efficient, and doesn’t let unused space go to waste.
‘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.’
The findings are reported online today in the journal Nature Neuroscience.
Dr Lomber and his team are conducting the research to improve understanding of how the brain handles cochlear implants, devices that can help the profoundly deaf hear again.
One question they want to answer is if the brain rewires itself to compensate for 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,’ said Dr Lomber.
‘They may not want to leave just because you’ve come back.’
In the study, the researchers compared visual localisation in three congenitally deaf cats and the same number of animals with normal hearing.
The cats were tested on their ability to spot lights, lines and moving dots.
Certain areas of the animals’ brains were then deactivated to see what difference it made to their performance.
Daily Mail UK