Wednesday, March 23, 2011

Canadian study shows blind people can "see" with their ears

From The Toronto Sun:

MONTREAL, Canada – Some blind people can "see" using their sense of hearing in a process that’s honed during infancy, a new study has found.

Researchers at the University of Montreal say the brain's sight centres can reorganize itself in blind people to receive acoustic and spatial information.

The lead researcher, Dr. Olivier Collignon, compared brain activity among two groups: 11 people born blind and another 11 who had sight.

Their research corroborates earlier studies that show the blind have a heightened sense of hearing. But Collignon says it's only recently that the researchers realized that the ears in blind people might be connected to their sight centres.

"These structures maintain a functional organization that’s comparable to what we see in a sighted person," said Collignon.

The area in question is the visual cortex, which takes images gathered by the eyes and processes them in a rear area of the brain known as the occipital lobe. This eye-to-brain communication is absent in people who are born blind.

Researchers exposed test subjects to sounds of varying tones and locations and then performed MRI scans of brain activity.

The visual cortex continued to process sound and spatial information even in blind subjects whose brains were not receiving information from their eyes.

"The brain (region) is so flexible that it’s able to carry out tasks which are similar to those required by the (ears)," said Collignon.

The findings raise questions about how and when the visual cortex re-wires itself in blind people. Collignon says the process might take place during childhood, but he says the theory requires further study.

The findings were published this week in Proceedings of the National Academy of Sciences.