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Blind `can develop bat-like sonar`

Last Updated: Thursday, May 26, 2011 - 00:00

London: In ray of hope for the blind, a research has found that visually challenged people can develop "sonar", that is, learning to navigate like bats by "seeing" objects from sounds reflected off them.

It`s well-known that bats use a biological version of sonar, called echolocation, to find their way around at night.

That blind humans could do it too was suspected but not known.

Now, Canadian researchers have proved that they can. Intriguingly, they did so by using a part of the brain normally involved in processing visual images. They discovered this by carrying out brain scans on two male volunteers, aged 43 and 27, who had both been blind since childhood.

Each was asked to stand outside and try to perceive different objects such as a car, a flag pole and a tree by making clicking noises and then picking up their very faint echoes. Tiny microphones were placed in the volunteers` ears to record the outgoing and incoming sounds.

The men later had these sounds played back to them, while their brain activity was monitored using functional magnetic resonance imaging (fMRI) scans. During playback, they were able to identify which object was which from the echoes.

The fMRI scans showed that these echoes were being processed by brain regions normally used to process visual information; no echo-related activity was seen in the auditory brain areas, which would be expected to process sound, `The Daily Telegraph` reported.


First Published: Thursday, May 26, 2011 - 00:00

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