Sonar vision system helps congenitally blind develop visual perception

Researchers from the Hebrew University of Jerusalem are developing a sonar vision device with which congenitally blind people can perceive the shape of a face, a house, or even words and letters. Using this device, the researchers have shown that in people that are blind from birth, the areas of the cerebral cortex normally devoted to reading become activated in response to stimulation.

The study was made by scientists from the Hebrew University of Jerusalem in conjunction with researchers at the ICM Brain and Bone Marrow Institute Research Center and NeuroSpin, and was published in Neuron.

The sonar vision system transforms images into sound, enabling perception of visual information via the ear. The system achieves this by using a combination of a video camera embedded in a pair of eyeglasses, a laptop, and headphones.  After only about 70 hours of specialized training in identifying shapes transformed into sound, a blind person is able to “see” and correctly classify images into different categories. They can also perceive where people are located in a room, identify certain facial expressions, and even read words and letters.

Another aspect of the study showed that certain regions of the cortex normally devoted to visual perception, and which seem to serve no apparent use in blind people, become highly activated after perception of an object’s “sonar vision.” The study also showed that the visual cortex also demonstrates “normal” functional selectivity of different object categories. These results support the idea that the visual cortex can perform selective analysis of object shapes based on visual input, but also, if necessary, based on auditory or tactile input. These also suggest the possibility of visual perception through the other senses.

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