Featured Research

from universities, journals, and other organizations

Brain Imaging Reveals New Language Circuits

Date:
December 28, 2004
Source:
John Wiley & Sons, Inc.
Summary:
The language network of the brain seemed simpler in the past. One brain area was recognized to be critical for the production of language, another for its comprehension. A dense bundle of nerve fibers connected the two. But there have always been naysayers who pointed to evidence that failed to fit this tidy picture. Now a study employing a powerful variant of magnetic resonance imaging (MRI) confirms these suspicions.

The language network of the brain seemed simpler in the past. One brain area was recognized to be critical for the production of language, another for its comprehension. A dense bundle of nerve fibers connected the two.

But there have always been naysayers who pointed to evidence that failed to fit this tidy picture. Now a study employing a powerful variant of magnetic resonance imaging (MRI) confirms these suspicions. The study will be published December 13, 2004 in the online edition of Annals of Neurology (http://www.interscience.wiley.com/journal/ana).

"We were surprised that the two classical language areas were densely connected to a third area, whose presence had already been suspected but whose connections with the classical network were unknown," said lead author Marco Catani, M.D., of the Institute of Psychiatry at King's College London.

The authors dubbed this language area "Geschwind's territory" in honor of the American neurologist Norman Geschwind who championed its linguistic significance decades ago.

Language is generated and understood in the cortex, the outermost covering of the brain. Paul Broca and Carl Wernicke, 19th Century neurologists, noted that damage to specific cortical areas, which came to bear their names, produced primarily language production or language processing disorders, but not both. A large bundle of nerve fibers was found to connect Broca's and Wernicke's areas, and damage to this pathway also produced language disorders, or aphasias.

However, even in the 19th Century, there were bits of evidence that other brain areas play some role in language, though these have remained enigmatic, as scientists could not use animal models to probe language networks in the same way they could visual or movement networks in the brain.

In the last few decades, advanced brain imaging techniques such as CT, PET, and more recently, MRI have allowed scientists to begin studying these areas in living humans.

Standard MRI, by itself a powerful innovation, shows the major tissue structures of the brain. A variant called "functional" MRI even allows researchers to identify which areas are being used during different tasks, including producing and comprehending language.

Diffusion tensor (DT) MRI has gained prominence in the past decade because it reveals in greater detail the nerve fiber connections through which different brain regions form communication networks.

With DT-MRI, Catani and his colleagues found a separate, roundabout route that connects Broca's and Wernicke's areas via a region in the parietal lobe of the cortex, which Geschwind had pointed out as an important language region already in the 1960s.

"There are clues that the parallel pathway network we found is important for the acquisition of language in childhood," said Catani. "Geschwind's territory is the last area in the brain to mature, the completion of its maturation coinciding with the development of reading and writing skills. An important future line of study will be to examine the maturation of this area and its connections in the context of autism and dyslexia."

The fact that these pathways appear to exist – in more rudimentary forms – in the brains of monkeys may also have bearing on the search for the evolutionary origins of language.

"These data suggest that language evolved, in part, from changes in pre-existing networks, not through the appearance of new brain structures," said Catani.

"This method provides another example of the remarkable versatility of MRI technology," said Marsel Mesulam, M.D., of Northwestern University in Chicago, Illinois, whose editorial will accompany the print publication of the article.

"It is theoretically possible to combine diffusion tensor imaging with functional MRI so as to reveal the connectivity of brain areas with identified specializations," said Mesulam. "This method can be applied anywhere in the brain. Revealing the connections of the human brain will constitute the next frontier in the field of cognitive neurology."

###

Article: "Perisylvian Language Networks of the Human Brain," Marco Catani, Derek K. Jones, and Dominic H. Ffytche, Annals of Neurology; Published Online: December 13, 2004 (DOI: 10.1002/ana.20319).

Editorial: "Imaging Connectivity in the Human Cerebral Cortex: The Next Frontier?" Marsel Mesulam, Annals of Neurology (DOI: 10.1002/ana.20368).

About the Annals of Neurology:

The Annals of Neurology, the preeminent neurological journal worldwide, is published by the American Neurological Association, the world's oldest and most prestigious neurological association. The 1,500 members of the ANA--selected from among the most respected academic neurologists and neuroscientists in North America and other countries--are devoted to furthering the understanding and treatment of nervous system disorders. For more information, visit http://www.aneuroa.org.


Story Source:

The above story is based on materials provided by John Wiley & Sons, Inc.. Note: Materials may be edited for content and length.


Cite This Page:

John Wiley & Sons, Inc.. "Brain Imaging Reveals New Language Circuits." ScienceDaily. ScienceDaily, 28 December 2004. <www.sciencedaily.com/releases/2004/12/041220023913.htm>.
John Wiley & Sons, Inc.. (2004, December 28). Brain Imaging Reveals New Language Circuits. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2004/12/041220023913.htm
John Wiley & Sons, Inc.. "Brain Imaging Reveals New Language Circuits." ScienceDaily. www.sciencedaily.com/releases/2004/12/041220023913.htm (accessed July 25, 2014).

Share This




More Mind & Brain News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Painkiller Designed To Discourage Abuse: Will It Work?

New Painkiller Designed To Discourage Abuse: Will It Work?

Newsy (July 24, 2014) The FDA approved Targiniq ER on Wednesday, a painkiller designed to keep users from abusing it. Like any new medication, however, it has doubters. Video provided by Newsy
Powered by NewsLook.com
Can Watching TV Make You Feel Like A Failure?

Can Watching TV Make You Feel Like A Failure?

Newsy (July 24, 2014) A study by German researchers claims watching TV while you're stressed out can make you feel guilty and like a failure. Video provided by Newsy
Powered by NewsLook.com
China's Ageing Millions Look Forward to Bleak Future

China's Ageing Millions Look Forward to Bleak Future

AFP (July 24, 2014) China's elderly population is expanding so quickly that children struggle to look after them, pushing them to do something unexpected in Chinese society- move their parents into a nursing home. Duration: 02:07 Video provided by AFP
Powered by NewsLook.com
Idaho Boy Helps Brother With Disabilities Complete Triathlon

Idaho Boy Helps Brother With Disabilities Complete Triathlon

Newsy (July 23, 2014) An 8-year-old boy helped his younger brother, who has a rare genetic condition that's confined him to a wheelchair, finish a triathlon. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins