This nicely maps to a blackboard architecture ( http://en.wikipedia.org/wiki/Blackboard_system), with the language-oriented Broca subunit playing the part of a specialist knowledge source, the cognitive-oriented Broca subunit acting as the local area of the blackboard used by that specialist, and the multiple demand network acting as the blackboard as a whole. Assuming this guess is correct, I'd love to be able to peek into the multiple demand network and see what format the information is exchanged in. I bet it would turn out being similar to a semantic net. Wild speculation sure is fun...
On Wed, Oct 17, 2012 at 8:53 AM, Mike Tintner <[email protected]>wrote: > Neuroscientists find Broca's area is really two subunits, each with its > own function > October 16th, 2012 in Neuroscience > > A century and a half ago, French physician Pierre Paul Broca found that > patients with damage to part of the brain's frontal lobe were unable to > speak more than a few words. Later dubbed Broca's area, this region is > believed to be critical for speech production and some aspects of language > comprehension. > > However, in recent years neuroscientists have observed activity in Broca's > area when people perform cognitive tasks that have nothing to do with > language, such as solving math problems or holding information in working > memory. Those findings have stimulated debate over whether Broca's area is > specific to language or plays a more general role in cognition. > > A new study from MIT may help resolve this longstanding question. The > researchers, led by Nancy Kanwisher, the Walter A. Rosenblith Professor of > Cognitive Neuroscience, found that Broca's area actually consists of two > distinct subunits. One of these focuses selectively on language processing, > while the other is part of a brainwide network that appears to act as a > central processing unit for general cognitive functions. > > "I think we've shown pretty convincingly that there are two distinct bits > that we should not be treating as a single region, and perhaps we shouldn't > even be talking about 'Broca's area' because it's not a functional unit," > says Evelina Fedorenko, a research scientist in Kanwisher's lab and lead > author of the new study, which recently appeared in the journal Current > Biology. > > Kanwisher and Fedorenko are members of MIT's Department of Brain and > Cognitive Sciences and the McGovern Institute for Brain Research. John > Duncan, a professor of neuroscience at the Cognition and Brain Sciences > Unit of the Medical Research Council in the United Kingdom, is also an > author of the paper. > > A general role > > Broca's area is located in the left inferior frontal cortex, above and > behind the left eye. For this study, the researchers set out to pinpoint > the functions of distinct sections of Broca's area by scanning subjects > with functional magnetic resonance imaging (fMRI) as they performed a > variety of cognitive tasks. > > To locate language-selective areas, the researchers asked subjects to read > either meaningful sentences or sequences of nonwords. A subset of Broca's > area lit up much more when the subjects processed meaningful sentences than > when they had to interpret nonwords. > > The researchers then measured brain activity as the subjects performed > easy and difficult versions of general cognitive tasks, such as doing a > math problem or holding a set of locations in memory. Parts of Broca's area > lit up during the more demanding versions of those tasks. Critically, > however, these regions were spatially distinct from the regions involved in > the language task. > > These data allowed the researchers to map, for each subject, two distinct > regions of Broca's area-one selectively involved in language, the other > involved in responding to many demanding cognitive tasks. The general > region surrounds the language region, but the exact shapes and locations of > the borders between the two vary from person to person. > > The general-function region of Broca's area appears to be part of a larger > network sometimes called the multiple demand network, which is active when > the brain is tackling a challenging task that requires a great deal of > focus. This network is distributed across frontal and parietal lobes in > both hemispheres of the brain, and all of its components appear to > communicate with one another. The language-selective section of Broca's > area also appears to be part of a larger network devoted to language > processing, spread throughout the brain's left hemisphere. > > Mapping functions > > The findings provide evidence that Broca's area should not be considered > to have uniform functionality, says Peter Hagoort, a professor of cognitive > neuroscience at Radboud University Nijmegen in the Netherlands. Hagoort, > who was not involved in this study, adds that more work is needed to > determine whether the language-selective areas might also be involved in > any other aspects of cognitive function. "For instance, the > language-selective region might play a role in the perception of music, > which was not tested in the current study," he says. > > The researchers are now trying to determine how the components of the > language network and the multiple demand network communicate internally, > and how the two networks communicate with each other. They also hope to > further investigate the functions of the two components of Broca's area. > > "In future studies, we should examine those subregions separately and try > to characterize them in terms of their contribution to various language > processes and other cognitive processes," Fedorenko says. > > More information: www.cell.com/curre. 2(12)01074-3 > > Provided by Massachusetts Institute of Technology > > This story is republished courtesy of MIT News (web.mit.edu/newsoffice/), > a popular site that covers news about MIT research, innovation and teaching. > > > > ------------------------------**------------- > AGI > Archives: > https://www.listbox.com/**member/archive/303/=now<https://www.listbox.com/member/archive/303/=now> > RSS Feed: https://www.listbox.com/**member/archive/rss/303/** > 23050605-bcb45fb4<https://www.listbox.com/member/archive/rss/303/23050605-bcb45fb4> > Modify Your Subscription: https://www.listbox.com/** > member/?&id_**secret=23050605-07077db3<https://www.listbox.com/member/?&;> > Powered by Listbox: http://www.listbox.com > ------------------------------------------- AGI Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/21088071-c97d2393 Modify Your Subscription: https://www.listbox.com/member/?member_id=21088071&id_secret=21088071-2484a968 Powered by Listbox: http://www.listbox.com
