May 26, 2011

Researchers Study Blind People’s Ability To Echolocate

Echolocation in bats and dolphins is well known. Bursts of sounds are created and the echoes that bounce back are used to locate and detect objects in the environment. What is less well known is that people can echolocate, too.

Blind people have been known to learn to make clicks with their mouths and to use the returning echoes from those clicks to sense their surroundings. Some of these people are so adept at echolocation that they can use this skill to go mountain biking, play basketball, or navigate unknown environments.

The part of the brain used by people who can echolocate has been identified by researchers in Canada. A study of two such people, published in PLoS ONE, highlighted a part of the brain was activated when listening to echoes, a part of the brain usually associated with sight.

The two subjects, who had been blind for many years were recorded echolocating. The researchers, from the University of Western Ontario, first made recordings of the clicks and their very faint echoes using tiny microphones in the ears of the blind echolocators as they stood outside and tried to identify different objects such as a car, a flag pole, and a tree.

The researchers then played the recorded sounds back to the echolocators while their brain activity was being measured in Western's state-of-the-art fMRI brain scanner.

Dr. Lore Thaler, from the university, explained in a statement: "This suggests that visual brain areas play an important role for echolocation in blind people. The study looked at only two people so cannot say for certain what happens in the brains of all people who learn the technique.

The study concludes that "[the two patients] use echolocation in a way that seems uncannily similar to vision."

Susie Roberts, rehabilitation officer at Action for Blind People, told BBC News: "This research into brain activity and echolocation is very interesting and improves our understanding of how some visually impaired people may be processing information to help them navigate safely. Further investigation may help to improve the way the technique is taught to people in the future, potentially improving their mobility and independence."


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