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Blind People have the Ability to Echolocate

May 30, 2011

(Ivanhoe Newswire) — Everybody has heard about echolocation in bats and dolphins. These creatures emit bursts of sounds and listen to the echoes that bounce back to detect objects in their environment. What is less well known is that people can echolocate, too. In fact, there are blind people who have learned 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.

Researchers at Western’s Centre for Brain and Mind have recently found evidence that blind echolocation experts use what is normally the ‘visual’ part of their brain to process the clicks and echoes.

The researchers 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 fMRI brain scanner. Remarkably, when the echolocation recordings were played back to the blind experts, not only did they perceive the objects based on the echoes, but they also showed activity in those areas of their brain that normally process visual information in sighted people. Most interestingly, the brain areas that process auditory information were no more activated by sound recordings of outdoor scenes containing echoes than they were by sound recordings of outdoor scenes with the echoes removed. Importantly, when the same experiment was carried out with sighted control people who did not echolocate, these individuals could not perceive the objects, and neither did their brain show any echo-related activity.

“This suggests that visual brain areas play an important role for echolocation in blind people,” lead author Lore Thaler, postdoctoral fellow at Western, was quoted as saying.

SOURCE: PLoS ONE, May 2011.




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