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January 31, 2014

Speaker: Dr. Estefania Ruiz Vargas

Title: Topological properties of modular networks, with a focus on networks of functional connections in the human brain

Abstract:The pathophysiology underlying neurocognitive dysfunction following mild traumatic brain injury (TBI), or concussion, is poorly understood. In order to shed light on the effects of TBI at the functional network or modular level we use mathematical and computational techniques to determine how modular structure changes in response to specific mechanisms of injury. In particular, we examine in detail the potential effects of focal contusions, diffuse axonal degeneration and diffuse microlesions, illustrating the extent to which functional modules are preserved or degenerated by each type of injury. We highlight other key differences among the effects of the three modeled injuries, and discuss their clinical implications. 

Within this modular framework, particular nodes which play key roles have been previously identified based on the node’s degree, and on the node’s participation coefficient. In this contribution, we develop a generalization of the participation coefficient, called the gateway coefficient, which measures not only the diversity of the intermodular connections, but also how critical these connections are to intermodular connectivity; in brief, nodes which form rare or unique gateways between sparsely connected modules rank highly in this measure.