People who are born blind often have heightened sensitivity in other senses such as touch or hearing, and now a study suggests why. According to the research, published online in PLOS One, the brains of individuals who are born blind lack visual stimulation, so instead, they make new connections that result in their other senses sharpening, and improvements in cognitive abilities, such as memory and language.

The study, conducted by researchers from Massachusetts Eye and Ear Infirmary, identified ways in which the brains of individuals who are born blind differ from those who can see or who acquired their eyesight later in life. According to the research, the visual sections in the brains of people blind from birth are not left unused; instead they are adapted and rewired for different purposes. This in turn helps to strengthen their other four senses and improves other mental functions.

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"Our results demonstrate that the structural and functional neuroplastic brain changes occurring as a result of early ocular blindness may be more widespread than initially thought," said lead author Corinna M. Bauer, in a recent statement on ScienceDaily. "We observed significant changes not only in the occipital cortex (where vision is processed), but also areas implicated in memory, language processing, and sensory motor functions."

For the study, the team looked at MRI scans of the brains of 12 individuals who were either born blind or who had become blind before they were three years old. The scientists then compared these scans to the scans of 16 individuals with normal eyesight. This revealed structural differences, as well as differences in functional connectivity, such as enhanced connections in the blind individuals that did not exist in their sighted counterparts.

Brain plasticity refers to the brain’s ability to change as it learns through life experiences, Sharpbrains reported. This can occur through learning, brain injury, or, as in the case of blind individuals, the loss of the need for a certain section of the brain. Other tasks, such as playing a musical instrument or speaking more than one language can also cause changes in brain connections. The brain rewires connections between neurons, resulting in different strengths, and also to compensate for injury.

The team hope that understanding how the brains of blind people change could lead to better methods of helping them, or make their lives easier.

"If the brain can rewire itself - perhaps through training and enhancing the use of other modalities like hearing, and touch and language tasks such as braille reading - there is tremendous potential for the brain to adapt," explained senior author Lotfi Merabet, in a recent statement.

Source: Bauer CM, Hirsch GV, Zajac L, Koo BB, Collognon O, Merabet LB. Multimodal MR-imaging reveals large-scale structural and functional connectivity changes in profound early blindness. PLOS One. 2017

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