XML Feed for RxPG News   Add RxPG News Headlines to My Yahoo!   Javascript Syndication for RxPG News

Research Health World General
 
  Home
 
 Latest Research
 Cancer
 Psychiatry
  Depression
  Neuropsychiatry
  Personality Disorders
  Bulimia
  Anxiety
  Substance Abuse
  Suicide
  CFS
  Psychoses
  Child Psychiatry
  Learning-Disabilities
  Psychology
   Cognitive Science
   Psychophysiology
   Behavioral Science
  Forensic Psychiatry
  Mood Disorders
  Sleep Disorders
  Peri-Natal Psychiatry
  Psychotherapy
  Anorexia Nervosa
 Genetics
 Surgery
 Aging
 Ophthalmology
 Gynaecology
 Neurosciences
 Pharmacology
 Cardiology
 Obstetrics
 Infectious Diseases
 Respiratory Medicine
 Pathology
 Endocrinology
 Immunology
 Nephrology
 Gastroenterology
 Biotechnology
 Radiology
 Dermatology
 Microbiology
 Haematology
 Dental
 ENT
 Environment
 Embryology
 Orthopedics
 Metabolism
 Anaethesia
 Paediatrics
 Public Health
 Urology
 Musculoskeletal
 Clinical Trials
 Physiology
 Biochemistry
 Cytology
 Traumatology
 Rheumatology
 
 Medical News
 Health
 Opinion
 Healthcare
 Professionals
 Launch
 Awards & Prizes
 
 Careers
 Medical
 Nursing
 Dental
 
 Special Topics
 Euthanasia
 Ethics
 Evolution
 Odd Medical News
 Feature
 
 World News
 Tsunami
 Epidemics
 Climate
 Business
Search

Last Updated: Nov 17th, 2006 - 22:35:04

Cognitive Science Channel
subscribe to Cognitive Science newsletter

Latest Research : Psychiatry : Psychology : Cognitive Science

   DISCUSS   |   EMAIL   |   PRINT
Brain networks change according to cognitive task
Jun 2, 2005, 16:10, Reviewed by: Dr.

"We found that one network takes different configurations depending on the goal of the task. Shifts of Effective Connectivity Within a Language Network during Rhyming and Spelling."

 
Using a newly released method to analyze functional magnetic resonance imaging (fMRI), Northwestern University researchers have demonstrated that the interconnections between different parts of the brain are dynamic and not static. This and other findings answer longstanding debates about how brain networks operate to solve different cognitive tasks. They are presented in the current (June 1) issue of the Journal of Neuroscience.

Equally important, the researchers discovered that the brain region that performed the integration of information shifted depending on the task their subjects performed. In this study, the subjects were assigned two language tasks. In both, subjects were asked to read individual words and then make a spelling or rhyming judgment.

"We found that one network takes different configurations depending on the goal of the task," said Tali Bitan, primary author of "Shifts of Effective Connectivity Within a Language Network during Rhyming and Spelling."

A post-doctoral fellow in the department of communication sciences and disorders, Bitan worked with Associate Professor James Booth of the same department and M-Marsel Mesulam, director of the Cognitive Neurology and Alzheimer's Disease Center in Northwestern's Feinberg School of Medicine.

Mesulam, who was among the first scientists to predict the existence of convergence zones within interconnected brain networks, said the study presents "the clearest and most convincing evidence to date" of the dynamics in effective connectivity.

To better understand dynamic effective connectivity, Mesulam compares the brain networks to a network of highways connecting different parts of a city. The highway is static. No matter how heavy the traffic load, it always has the same number of lanes. In the brain, there is a dynamic change that allows certain pathways to preferentially facilitate the demands of a given cognitive task. The brain highway in effect "adds lanes" to accommodate the requirements of the particular task.

Depending on the goal of the task -- whether subjects were asked to make an orthographic (spelling) judgment or a phonological (rhyming) judgment the Northwestern researchers found that different convergence zones in the network were involved in the task.

"The existence and the identity of convergence zones --areas in which information from multiple sources meets in the brain -- have been debated since they were proposed in the late 20th century," said Bitan. "Now, with new techniques to analyze brain imaging data, we can examine the specific role played by different brain regions in the network that are required for any cognitive task. These techniques examining effective connectivity enable us to learn how the brain changes its interconnectivity according to the task at hand."

The Northwestern researchers also propose to explain the role of each brain region as it interacts within a complex network to achieve a specific cognitive goal.

The conventional method for analyzing fMRI data, which can only show which brain regions are active in a given task, showed two brain regions that were specifically active for each of the studied tasks: the lateral temporal cortex (LTC) for the rhyming task and the intraparietal sulcus (IPS) for the spelling task.

In addition to the task-specific regions, the inferior frontal gyrus (IFG) and the fusiform gyrus (FG) were engaged by both tasks. Dynamic Causal Modeling, the new method examining the influences between brain regions, indicates that each task preferentially strengthened the influences converging on the task specific regions (LTC for rhyming, IPS for spelling). This finding suggests that task specific regions serve as convergence zones that integrate information from other parts of the brain.

The results also show that switching between tasks -- in this case between rhyming and spelling -- led to changes in the influence of the IFG on the task specific regions. This finding suggests the IFG plays a pivotal role in "making" task specific regions more or less sensitive, depending on the task.

"Previous studies showed that the IFG is active in many different language tasks and suggested that the IFG was involved not only in the integration process but also in control of other brain regions," Bitan said. "Our study corroborates the role of the IFG in modulating other brain regions. In contrast, however, it shows that the integration process is done primarily in the task-specific regions."

In the 19th and early 20th century, scientists with a "localizationist" approach postulated that discrete brain regions were associated with specific functions of language and memory. By the end of the 20th century, a "connectionist" view stressing the importance of interconnected networks became the consensus.

The research presented in the Journal of Neuroscience effectively sets the stage for further development in our understanding of neuroscience. In their article, the Northwestern scientists provide evidence of the ways in which different cognitive goals are achieved from the interaction between different brain regions.
 

- Northwestern University
 

www.northwestern.edu

 
Subscribe to Cognitive Science Newsletter
E-mail Address:

 

In addition to Bitan, Booth and Mesulam, co-authors of the article are Janet Choy and Douglas Burman of Northwestern's communication sciences and disorders department and Darren Gitelman, associate professor of neuology at Northwestern University Feinberg School of Medicine.

Related Cognitive Science News

Mice learn set shifting tasks to help treat human psychiatric disorders
Broca's area also organizes behavioral hierarchies
Erotic images elicit strong response from brain
Prosopagnosia may affect 2 percent of population
Nerve cells in brain decide between apples and oranges
How Visual Stimulation Turns Up Bdnf Genes to Shape the Brain
Humans perceive more than they think they do
Specific Mechanisms May Not Exist For Facial Recognition
Scent of fear impacts cognitive performance
Older people with stronger cognitive skills walk at a safer pace


For any corrections of factual information, to contact the editors or to send any medical news or health news press releases, use feedback form

Top of Page

 

© Copyright 2004 onwards by RxPG Medical Solutions Private Limited
Contact Us