Substitution for sight in blind people’s brains

Some blind individuals can use echoes from tongue or finger clicks to recognise objects in the distance.

And in these individuals, echolocation is a full form of sensory substitution, using regions of the brain normally associated with visual perception, research by Mel Goodale, from the University of Western Ontario, in Canada, has found.

Dr. Goodale’s latest results were presented at the 9th Annual Canadian Neuroscience Meeting yesterday in Vancouver.

“Our experiments show that echolocation is not just a tool to help visually impaired individuals navigate their environment, but can act as an effective sensory replacement for vision, allowing them to recognise the shape, size, and material properties of objects” says Goodale.

Just as the size, expected weight, texture and composition of an object can be assessed by visual cues, Goodale’s research shows that the same is true of information obtained through the auditory cues provided by echolocation.

Many of the same regions in the sighted brain that are used for the visual assessment of objects are recruited in the blind brain when objects are explored using echolocation.

“Remarkably, expert blind echolocators can tell whether something is hard or soft, dense or not, just by listening to the echoes bouncing back from that material,” notes Dr. Goodale.

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