Brain adapts to give deaf people a better visual ‘danger radar’

Pioneering research shows that the brains of people who are deaf from an early age rewire to see more of what is happening in their visual periphery, new research has revealed.

Scientists have discovered that lifelong deafness is associated with a redistribution of neural resources in two of the brain’s earliest visual processing structures, helping explain why D/deaf adults (a term encompassing both those with medical hearing loss and the cultural identity of the deaf community) can be particularly skilled at detecting movement and events outside their central field of view.

This potentially gives them an advantage when monitoring their surroundings for movement or danger.

Researchers at the University of Sheffield and University of York studied 16 adults with early, profound deafness and 16 hearing adults, all of similar ages, using functional MRI to map how the brain represents different parts of the visual field.

Their study, published in the Proceedings of the National Academy of Sciences, found that the D/deaf participants had a greater representation of far-peripheral vision in both the primary visual cortex and the lateral geniculate nucleus (LGN), a visual relay structure deep within the brain.

Importantly, the brain had not simply expanded its overall visual processing capacity. Instead, researchers found evidence of a redistribution of neural resources, with relatively more resources devoted to peripheral vision and fewer to the central visual field.

Professor Charlotte Codina, professional lead for orthoptics and ophthalmology at the University of Sheffield’s School of Allied Health Professions, Pharmacy, Nursing and Midwifery, said, “This study suggests that the brain can profoundly adapt to make the most of its sensory environment, and as a result deaf people have superior peripheral vision.

“It wasn’t previously known that the brain could adapt to its environment to such a great extent. This significant finding could pave the way to a greater understanding of how the brain changes to make the best of its sensory loss.”

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Lisa Lock

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Robert Egan

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