Blind people echolocate with visual part of brain
By Emily Chung, CBC News
Posted: May 25, 2011 5:01 PM ET
Last Updated: May 25, 2011 5:11 PM ET
Blind people who navigate using clicks and echoes, like bats and dolphins do, recruit the part of the brain used by sighted people to see, a new study has found.
While few blind people use echolocation — emitting a sound and then listening for the echo to get information about objects in the surroundings — some that do are so good at it that they can use the ability to hike, mountain bike and play basketball, said Melvyn Goodale, one of the co-authors of the study published Wednesday in PloS One.
Goodale, a psychology professor and the director of the Centre for Brain and Mind at the University of Western Ontario in London, Ont., said he was amazed by the abilities of the two blind men in the study.
"They can tell a flat thing from convex. They can tell a bush from a wall, a car from a lamp post," he said. One of the two subjects, Daniel Kish, 43, could localize objects to within three degrees — "incredibly accurate," Goodale said.
Both Kish and a 27-year-old male subject trained by Kish could also tell which way objects were moving. Goodale and his research team wanted to find out what was happening in the brain while people like Kish were echolocating.
In order to do that, they used a technique called fMRI (functional magnetic resonance imaging), which detects changes in oxygen consumption by different parts of the brain while it is performing a certain task.
For example, if a person is watching something, the visual part of the brain lights up because it uses more oxygen for that task.
The researchers found that when echolocators were listening to their echolocation clicks and echoes, the part of the brain normally used to see lights up.
"The job of understanding the echoes seemed to be the job of this remaining visual cortex," Goodale said. In fact, when Kish was using echolocation to detect moving objects, the part of brain that is used to see moving objects lit up.
No special activity in hearing part of brain
What's interesting, Goodale added, is that the echoes don't cause any unusual activity in the part of the brain used for hearing — it isn't affected by the echoes more than any other sound.
The experiment was a challenge to design because fMRI involves scanning the subjects while they are lying down in a small tunnel. University of Western Ontario"So it must actually extract information about the echoes, but then it passes it onto the visual cortex where it's analyzed," Goodale said.
Two men who could see and did not use echolocation were also scanned, and the visual part of their brain did not light up when they heard the echolocation sounds.
Goodale said the experiment was a challenge to design because fMRI involves scanning the subjects while they are lying down in a small tunnel.
Because of that, lead author and postdoctoral research Lore Thaler and co-author Stephen Arnott created an experiment designed to mimic echolocation inside the fMRI machine. They placed microphones in the ears of the echolocators and recorded them echolocating outside. Then they played the sounds back to them inside the machine both as is and with the echoes deleted.
Goodale said while he found the results very interesting scientifically, he was most struck by the abilities of the echolocators themselves.
Something that Kish would add, he said, is: "I think this can be quite a liberating skill for the blind. Not all blind people know about this and I think if more did and more had an opportunity to learn, then, they might find that their ability to understand the world well beyond their bodies is much better than they think it is."
The research was funded by the Canadian Institutes of Health Research and the Ontario Ministry of Research and Innovation.When a blind echolocation expert (left) hears the clicks and echoes of his echolocation, his brain lights up in the fMRI scan. The brain of a seeing man who does not echolocate (right) does not light up. University of Western Ontario
Top News Headlines
- Harper to address Tory caucus amid Senate scandal
- Conservatives gathered Monday night to mourn the passing of a key architect in their rise to power — and to brace for the toughest test Prime Minister Stephen Harper's government has faced since taking office on a promise to clean up politics in the national capital. more »
- Keith Boag: Have you heard about the murderous abortion doctor?
- The gruesome trial and murder conviction of Philadelphia abortion provider Dr. Kermit Gosnell is unlikely to change American abortion law, Keith Boag writes. But it has U.S. journalists questioning their priorities and how they cover such a sensitive issue. more »
- Fearful Oklahoma families search for children
- The parents and guardians stood in the muddy grass outside a suburban Oklahoma City church, listening intently as someone with a bullhorn called out the names of children who were being dropped off — survivors of Monday's deadly tornado. more »
- Baseball fuels dreams, desperation in Dominican Republic
- The Toronto Blue Jays have a number of stars from the Dominican Republic, but in the shadow of these successful players is an equally important story about hope and poverty, and a country desperately struggling to balance the two. more »
Latest Technology & Science News Headlines
- Xbox launch Tuesday highly anticipated
- Microsoft's next-generation Xbox expected to be revealed Tuesday, and anticipation for the entertainment console's latest evolution is running high. more »
- Netflix and the rise of binge TV watching
- Netflix has been giving viewers the opportunity to watch entire new seasons of TV shows in one sitting and — for better or for worse — many have been doing just that. more »
- Astronaut Chris Hadfield adjusts to 'earthling' life
- Canada's space ambassador, Chris Hadfield, is still readapting to life on this planet after spending 146 days in zero gravity as commander of the International Space Station. For now, though, he's taking his homecoming one step at a time. more »
- Bell Mobility to appeal ruling in 911 lawsuit
- Bell Mobility says the company plans to appeal a Northwest Territories Supreme Court ruling that says the company is liable for charging 911 fees to customers that aren't receiving the service. more »
Bob McDonald's Blog
- Chris Hadfield: The gravity of gravity May. 17, 2013 9:58 AM After five months of being Superman and a media superstar, Canadian astronaut Chris Hadfield is now beginning the challenging task of adapting his mortal body and brain to life back on Earth.
Quirks & Quarks
- May 18: Apps for Apes May. 17, 2013 4:26 PM Scientists at more than 2 dozen zoos around the world, including the Toronto Zoo, have been using computer tablets to stimulate our bright orange primate cousins, the orangutans. And the orangutans have been loving it.
- Oklahoma tornado rescue crews work through night
- 51 dead after tornado levels Oklahoma suburbs
- Edmonton driver, 62, charged in boy's patio death
- Unknown remains found on Dellen Millard's farm
- Will alleged Rob Ford video overshadow Toronto casino debate?
- Netflix and the rise of binge TV watching
- Ray Manzarek of The Doors dies at 74
- B.C. man feared kidnapped in Mexico
- Canadian on EI shut out amid foreign worker influx