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 acco