Back to web version
Effects of a concussion on the brain
By PETE GRATHOFFThe Kansas City Star
Big hits are a major attraction in football.
How many times have we seen a football player left dazed after a big hit? Often, a player’s eyes will look vacant, leaving a spectator or announcer to remark: “There’s nothing going on upstairs.”
In reality, the opposite is true. There is an amazing amount of activity as the brain tries fixing itself after a concussion.
When investigating the effects of a concussion, it is best to begin by looking at the basic wiring of the brain.
According to the Society for Neuroscience, the human brain has approximately 100 billion neurons, which are specialized cells designed to transmit information to other nerve cells. The basic working unit of the brain, neurons communicate with one another along their axons.
Axons are an extension of the cell body and they transmit electro-chemical signals to other neurons.
The brain itself is surrounded by cerebrospinal fluid, but that offers little protection.
A concussion occurs when a football player’s head hits the ground or another player and the brain slams into the skull.
The book The Heads-up on Sports Concussion by Gary S. Solomon, Karen M. Johnston and Mark R. Lovell describes what happens.
That impact damages blood vessels, while the axons can be twisted and stretched, causing some to die. The neurons start firing.
The authors wrote that potassium exits brain cells at up to 400 percent of normal rate, while calcium enters the brain at up to 500 percent of the normal rate. To fuel the absorption of potassium, the neurons consume glucose.
“Blood flow in the brain then decreases up to 50 percent within 2 minutes of the concussive impact, possibly due to the disruption of the normal calcium processes,” the authors wrote.
“Along with this chemical cascade, the brain begins to work overtime (a state known as hypermetabolism) trying to restore a chemical balance. … But there is less oxygen and glucose (brain fuels) to use as an energy source because blood flow in the brain is reduced. It’s like trying to catch the lead car on the last lap of a NASCAR race with less than half the normal flow of gas to the engine. Aspects of hypermetabolism can last a day or more.”
This exhausts the neurons and is the reason there is mental confusion and memory troubles.
“The brain enters a state of hypometabolism (decreased functioning, often called ‘resting depression’), which can last five to 10-plus days, until blood flow levels in the brain are returned to normal (restored autoregulation of brain’s electrochemical and blood-flow processes),” the authors wrote. “This appears to be the time when the brain heals itself.”
According to an article in Discover magazine, a concussion can impair learning over a period of years.