What Happens to a Linebacker’s Neurons?

Rest Day Read (SR-42)
The Brain: What Happens to a Linebacker’s Neurons?
by Carl Zimmer (Discover Magazine July-Aug, 2010)
“The brain floats in a sealed chamber of cerebrospinal fluid, like a sponge in a jar of water. If you quickly sit down in a chair, you accelerate your brain. The force you generate can cause it to swirl around and shift its shape inside the braincase. The brain is constantly twisting, stretching, and squashing within your head. Given the delicacy of the organ—a living brain has the consistency of custard—it is amazing that we manage to get to the end of each day without suffering severe damage.”
“It turns out that axons are remarkably elastic. They can stretch out slowly to twice their ordinary length and then pull back again without any harm. Axons are stretchy due in part to their flexible internal skeleton. Instead of rigid bones, axons are built around structural elements, mostly bundles of filaments called microtubules. When an axon stretches, these microtubules can slide past one another. If the movement is gradual, the microtubules will immediately slide back into place after the stretching stops, with no harm done.

If (Dr. Douglas) Smith delivers a quick, sharp puff of air, however, something else entirely happens. Instead of recoiling smoothly, the axon develops kinks. Over the next 40 minutes, the axon gradually returns to its regular shape, but after an hour a series of swellings appears. Each swelling may be up to 50 times as wide as the normal diameter of the axon. Eventually the axon falls apart.”

“Smith’s research also suggests that even mild shocks to the brain can cause serious harm. If he hit his axons with gentle puffs of air, they didn’t swell and break. Nevertheless, there was a major change in their molecular structure. Axons create the electric current that allows them to send signals by drawing in negatively charged sodium atoms. A moderate stretch to an axon, Smith recently found, causes the sodium channels to malfunction.

Smith suspects that such a mended axon may be able to go on working, but only in a very frail state. Another stretch—even a moderate one—can cause the axon to go haywire…in a runaway feedback loop. The axon dies like a shorted-out circuit.

This slower type of axon death may happen when someone suffers mild but repeated brain injuries, exactly the kind that football players experience as they crash into each other in game after game. Cognitive tests like the ones at this year’s N.F.L. combine can pinpoint the mental troubles that come with dysfunctional or dying axons. There is precious little research to indicate how long a football player should be sidelined in order to let his brain recover, though, and Smith’s experiments don’t offer much comfort. Preliminary brain studies show that axons are still vulnerable even months after an initial stretch.”

Scary. That what this is. Scary for parents, coaches and administrators of athletes, especially football athletes. This research in the cellular mechanisms of brain injuries by Dr. Douglas Smith at the U of Pennsylvania Center for Brain Injury and Repair, shows a problem much deeper than previously thought.

I’ve read reports of dementia, speech loss, headaches, ALS-like syndrome and even severe depression associated with multiple concussions in football players. I remember my own players asking me things like, “Coach, let’s go to the bake sale and buy cookies”, DURING football games. On ESPN radio several years ago, Merril Hodge, an ex-NFL player with the Steelers and now ESPN analyst, told his story of a two year period after he retired (due to head injuries) where he could not even walk around the block at his own home because he would get lost.

Fortunately, many groups, led by the NFL, have taken the first steps in identifying, treating and preventing traumatic brain injuries. Hopefully, the more we learn about the causes of the damage, the more we can begin to formulate treatments and preventions.

As football starts for the 2010 season, please be careful out there young men. Be smart and keep your head out of the game!

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