Douglas H. Smith, MD, is the Robert A. Groff Endowed Professor Neurosurgery and Director of the Center for Brain Injury and Repair at the University of Pennsylvania. He is the Scientific Director of the Big 10/Ivy League Collaboration on Concussion and also serves as a member on the Scientific Advisory Boards of the US National Football League (NFL), the National Collegiate Athletic Association (NCAA)-DoD consortium on concussion, and the International Concussion Society. 

This is the first of a two-part series. In this one, he points out that: 

An objective is to look at the biomechanics of concussion and how that selectively induces injuries to axons, and how to detect it non-invasively. Also, how does that time zero, when the injury occurs, cause neurodegeneration later on? It is weird that the definition of a concussion does not include what is going on in the brain, which is an actual true definition of a diagnosis. He showed different pathologies in concussion. White matter in the brain in particular seems vulnerable to the forces of a concussion. He discussed the role of axons in a brain injury, noting that Tau is our selective marker for axons. He talked about how multiple swelling occurs along the axon. Think of the brain being a kind of eavesdropping system, a shadow network.  He indicated that in a sports injury in soccer, there is a higher rate of concussion and a worse outcome for women. Male axons are bigger and have a more complex microtubular array. On average, smaller axons are more vulnerable and subject to greater dysfunction and loss of synchrony, so normal functions of networks are impaired in females compared to males. Another change that does a lot in a concussion is disruption of the blood brain barrier. Think of a blood brain barrier disruption map as where we see the distribution of axonal pathology.