Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

MIT-- parts of brain can switch functions

01.03.2011
In people born blind, brain regions that usually process vision can tackle language

When your brain encounters sensory stimuli, such as the scent of your morning coffee or the sound of a honking car, that input gets shuttled to the appropriate brain region for analysis. The coffee aroma goes to the olfactory cortex, while sounds are processed in the auditory cortex.

That division of labor suggests that the brain's structure follows a predetermined, genetic blueprint. However, evidence is mounting that brain regions can take over functions they were not genetically destined to perform. In a landmark 1996 study of people blinded early in life, neuroscientists showed that the visual cortex could participate in a nonvisual function — reading Braille.

Now, a study from MIT neuroscientists shows that in individuals born blind, parts of the visual cortex are recruited for language processing. The finding suggests that the visual cortex can dramatically change its function — from visual processing to language — and it also appears to overturn the idea that language processing can only occur in highly specialized brain regions that are genetically programmed for language tasks.

"Your brain is not a prepackaged kind of thing. It doesn't develop along a fixed trajectory, rather, it's a self-building toolkit. The building process is profoundly influenced by the experiences you have during your development," says Marina Bedny, an MIT postdoctoral associate in the Department of Brain and Cognitive Sciences and lead author of the study, which appears in the Proceedings of the National Academy of Sciences the week of Feb. 28.

Flexible connections

For more than a century, neuroscientists have known that two specialized brain regions — called Broca's area and Wernicke's area — are necessary to produce and understand language, respectively. Those areas are thought to have intrinsic properties, such as specific internal arrangement of cells and connectivity with other brain regions, which make them uniquely suited to process language.

Other functions — including vision and hearing — also have distinct processing centers in the sensory cortices. However, there appears to be some flexibility in assigning brain functions. Previous studies in animals (in the laboratory of Mriganka Sur, MIT professor of brain and cognitive sciences) have shown that sensory brain regions can process information from a different sense if input is rewired to them surgically early in life. For example, connecting the eyes to the auditory cortex can provoke that brain region to process images instead of sounds.

Until now, no such evidence existed for flexibility in language processing. Previous studies of congenitally blind people had shown some activity in the left visual cortex of blind subjects during some verbal tasks, such as reading Braille, but no one had shown that this might indicate full-fledged language processing.

Bedny and her colleagues, including senior author Rebecca Saxe, assistant professor of brain and cognitive sciences, and Alvaro Pascual-Leone, professor of neurology at Harvard Medical School, set out to investigate whether visual brain regions in blind people might be involved in more complex language tasks, such as processing sentence structure and analyzing word meanings.

To do that, the researchers scanned blind subjects (using functional magnetic resonance imaging) as they performed a sentence comprehension task. The researchers hypothesized that if the visual cortex was involved in language processing, those brain areas should show the same sensitivity to linguistic information as classic language areas such as Broca's and Wernicke's areas.

They found that was indeed the case — visual brain regions were sensitive to sentence structure and word meanings in the same way as classic language regions, Bedny says. "The idea that these brain regions could go from vision to language is just crazy," she says. "It suggests that the intrinsic function of a brain area is constrained only loosely, and that experience can have really a big impact on the function of a piece of brain tissue."

Bedny notes that the research does not refute the idea that the human brain needs Broca's and Wernicke's areas for language. "We haven't shown that every possible part of language can be supported by this part of the brain [the visual cortex]. It just suggests that a part of the brain can participate in language processing without having evolved to do so," she says.

Redistribution

One unanswered question is why the visual cortex would be recruited for language processing, when the language processing areas of blind people already function normally. According to Bedny, it may be the result of a natural redistribution of tasks during brain development.

"As these brain functions are getting parceled out, the visual cortex isn't getting its typical function, which is to do vision. And so it enters this competitive game of who's going to do what. The whole developmental dynamic has changed," she says.

This study, combined with other studies of blind people, suggest that different parts of the visual cortex get divvied up for different functions during development, Bedny says. A subset of (left-brain) visual areas appears to be involved in language, including the left primary visual cortex.

It's possible that this redistribution gives blind people an advantage in language processing. The researchers are planning follow-up work in which they will study whether blind people perform better than sighted people in complex language tasks such as parsing complicated sentences or performing language tests while being distracted.

The researchers are also working to pinpoint more precisely the visual cortex's role in language processing, and they are studying blind children to figure out when during development the visual cortex starts processing language.

Written by Anne Trafton, MIT News Office

Anne Trafton | EurekAlert!
Further information:
http://www.mit.edu

More articles from Health and Medicine:

nachricht Researchers release the brakes on the immune system
18.10.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht Norovirus evades immune system by hiding out in rare gut cells
12.10.2017 | University of Pennsylvania School of Medicine

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>