Some Blind “See” with Their Ears

Dr. Olivier Collignon of the University of Montreal's Saint-Justine Hospital Research Centre compared the brain activity of people who can see and people who were born blind, and discovered that the part of the brain that normally works with our eyes to process vision and space perception can actually rewire itself to process sound information instead. The research was undertaken in collaboration with Dr Franco Lepore of the Centre for Research in Neuropsychology and Cognition and was published in the March 15, 2011 issue of PNAS. The research builds on other studies which show that the blind have a heightened ability to process sounds as part of their space perception. "Although several studies have shown occipital regions of people who were born blind to be involved in nonvisual processing, whether the functional organization of the visual cortex observed in sighted individuals is maintained in the rewired occipital regions of the blind has only been recently investigated," Dr. Collignon said. The visual cortex is responsible for processing sight. The right and left hemisphere of the brain have one each. They are located at the back of the brain, which is called the occipital lobe. "Our study reveals that some regions of the right dorsal occipital stream do not require visual experience to develop a specialization for the processing of spatial information and are functionally integrated in the preexisting brain network dedicated to this ability." The researchers worked with 11 individuals who were born blind and 11 who were not. Their brain activity was analyzed via MRI scanning while they were subjected to a series of tones. "The results demonstrate the brain's amazing plasticity," Dr. Collignon said.