A new study delves into the neurological changes in people with blindness. It demonstrates that losing one’s sight before the age of 3 causes long-term alterations and subsequent enhancements to the other senses. Share on Pinterest New research aims to show how the brain compensates for blindness. It has long been theorized that individuals who lose one of their senses, or who have it significantly reduced, “make up” for this deficit with their other senses. Even back in the 18th century, philosopher Denis Diderot wrote in awe about a blind mathematician who could distinguish real coins from fake ones just by touching them. Although the brain’s ability to compensate in response to a lack of visual stimulation is considered common knowledge, it was not until the 1990s and the advent of brain imaging that the theory could be confirmed. Today, the precise changes that occur in the brain are still being unpicked. For instance, a 2009 study conducted at University of California-Los Angeles’ Laboratory of Neuroimaging, uncovered some of the details. Using sensitive brain imaging techniques, they found that, in blind people, visual regions of the brain were small compared with those with normal sight, but nonvisual areas were larger in volume. Although this marked a step toward understanding this process, the exact changes in the brain are still poorly understood.

Comparing sighted and blind brains A recent study set out to chart these brain changes in more detail. The study was led by Massachusetts Eye and Ear researchers and is published today in PLOS One. For the first time, the team combines structural, functional, and anatomical brain changes and compares blind people’s brains with those of people with normal sight. To develop a picture of the brain changes that occur, the team used both diffusion-based and resting state MRI. In all, 28 participants took part in the study: 12 were either blind from birth or had become blind before the age of 3, and 16 participants had normal sight. The scans of individuals with early blindness showed clear differences from the control scans of normally sighted participants, so changes in structural and functional connectivity could be measured. Enhanced connections between specific parts of the brain were seen in the blind people that were not present in the control group. These observed differences surprised researchers: “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.” Corinna M. Bauer, Ph.D., lead author Bauer, a teacher of ophthalmology at Harvard Medical School in Boston, MA, continues: “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.”