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Reassessing neural center strength through the scope of network connectivity.

! Cognitive neuroscience has long sought to assign objective ranking to importance of neural centers in the brain. Historically, scientists have focused on sheer number of connections between cortical areas in this ranking; the thought being that the most integrated cortical areas would yield the greatest damage if disrupted. This approach to graph construction of neural networks establishes hubs as nodes, and the edges connecting these nodes are weighted by looking at the connectivity of the upstream node. Through this approach, modern neuroscience has been able to categorize severity of neural damage and anticipate the types of damage to be seen. Doctors, contradicting the expectations of this graph, have long observed that despite having similar locations or extent of brain injury, patients often present with wide-ranging degrees of impairment and exhibit different recovery trajectories. !
! In research published online Sept. 15 in the Early Edition of the Proceedings of the National Academy of Sciences, scientists studied neurological patients with focal brain damage, and found that damage to six hub locations produced much greater cognitive impairment than damage to other locations. Upon reflection of this research, many cognitive neuroscientists argued that the number of connections a given region makes may not reflect the importance of a region to network function because it can be strongly influenced by network size. Instead, their framework defined hubs as brain regions that show correlated activity with multiple brain systems (rather than regions). The authors predicted that because hubs should be critical for brain function and complex cognition, damage to true hubs should produce widespread cognitive impairment. Preliminary medical research supported their claim; on average, patients with damage to these redefined hubs had significant impairment in nine major cognitive domains (attention, perception, memory, language skills, motor performance, reasoning, executive functions, emotional functions, and adaptive functions). In contrast, the group with lesions to historical hubs was significantly impaired in just three of the nine domains. It is the hope of these researchers to use this paradigm shift of hub assignment to reform the graph of neural networks and it’s edge weightings. A better understanding of brain networks and hubs likely will help with understanding of outcomes of brain injuries, as well as help predict extent of d!amage and aid in rehabilitation. !

http://medicalxpress.com/news/2014-09-network-neuropsychological-outcome-brain-injury.htmls

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