New York Times: Derek Boogaard's Brain Injury
Derek Boogaard's brain was preserved. Although the Hockey player was dead, a request came to the family to not cremate Boogaard until they could carve his brain out of his skull to study it. That was May 2011. The results came in October.
Boogaard had chronic traumatic encephalopathy, commonly known as C.T.E., a close relative of Alzheimer’s disease. It is believed to be caused by repeated blows to the head. It can be diagnosed only posthumously, but scientists say it shows itself in symptoms like memory loss, impulsiveness, mood swings, even addiction.
More than 20 dead former N.F.L. players and many boxers have had C.T.E. diagnosed. Typically they are left in a permanently scarred state in later life.
The issue of repeated trauma is explained in a video. To read more about this particular case you can read the New York Times Article.
The Center for the Study of Chronic Traumatic Encephalopathy states the following:
Chronic Traumatic Encephalopathy (CTE) is a progressive degenerative disease of the brain found in athletes (and others) with a history of repetitive brain trauma, including symptomatic concussions as well as asymptomatic subconcussive hits to the head. CTE has been known to affect boxers since the 1920s. However, recent reports have been published of neuropathologically confirmed CTE in retired professional football players and other athletes who have a history of repetitive brain trauma. This trauma triggers progressive degeneration of the brain tissue, including the build-up of an abnormal protein called tau. These changes in the brain can begin months, years, or even decades after the last brain trauma or end of active athletic involvement. The brain degeneration is associated with memory loss, confusion, impaired judgment, impulse control problems, aggression, depression, and, eventually, progressive dementia.
A new paper published in the Journal of Neuropathology and Experimental Neurology suggests head trauma may also lead to a neurodegenerative disorder mimicking ALS. This paper adds to literature suggesting an elevated risk of ALS in veterans and professional soccer players who have suffered head injuries, and is certain to contribute to the controversy regarding the link between head trauma and ALS. A recent article in the New York Times points out that Lou Gehrig himself may have had this entity rather than ALS.
Researchers at Albert Einstein College of Medicine of Yeshiva University and Montefiore Medical Center, the University Hospital and academic medical center for Einstein, used diffusion tensor imaging, an advanced type of MRI-based imaging technique, as well as cognitive tests, to assess brain function in amateur football players. Their findings indicate the possibility of brain injury from frequently heading the ball.
The brain is a complex system made of billions of neurons and thousands of connections that relate to every human feeling, including one of the strongest emotions, fear. Most neurological fear studies have been rooted in fear-conditioning experiments. Now, University of Missouri researchers have started using computational models of the brain, making it easier to study the brain's connections. Guoshi Li, an electrical and computer engineering doctoral student, has discovered new evidence on how the brain reacts to fear, including important findings that could help victims of post-traumatic stress disorder (PTSD). 
Mild & Minor Traumatic Brain Injury: An Unfortunate Oxymoron (Part 1)
