1. Concussions Models and Evidence

2. Introduction: A concussion is an injury to the brain caused by a blow to the head. Athletes, such as football players, sometimes get concussions during games and practices. People can also get concussions from falls, car crashes, and biking accidents. Problem: What happens to the brain after a concussion? Scientists want to find out what happens to the brain when a person gets a concussion.

4. Evidence 1 Scientists have found that many people have trouble remembering some things after a concussion. They often forget what happened before or after they hit their head. In addition, in one study, scientists found that 71% of athletes who got concussions had headaches in the first day after the concussion.

5. Evidence 2 Neurologists (scientists who study the brain) studied the brains of 20 two-year-old rats with serious concussions one year after their concussion. They used brain scanning machines to look at the brain tissue. They found that these rats had some damaged brain tissue with dead brain cells. The neurologists also examined the brain tissue of 20 three-year- old rats that had not had any concussions. These rats did not have damaged brain tissue with dead brain cells. In the picture, the left image shows a small piece of brain tissue from a typical rat that had not had any concussions, and the right image shows a small piece of brain tissue from a typical rat that had had a serious concussion. Brain tissue from rat without concussions Brain tissue from rat with concussions

6. Evidence 3 Scientists examined the brains of one two-year-old rat before and after it received a mild concussion. They used brain imaging machines to take pictures of the rat’s brain. The pictures show the electrical activity of the brain cells before and in the minutes following the concussion. In the pictures, the dark spots indicate locations of high electrical activity. Point of concussion (impact)

7. Evidence 4 Scientists studied the effects of a drug called Naloxone on cats that had suffered concussions. Naloxone is a drug that helps get more blood flowing through blood vessels in the brain. Blood carries oxygen and nutrients to brain cells. It is important that there is enough blood flowing through the brain vessels so that the brain cells can live. The scientists studied 26 cats. 13 cats had serious concussions, and these cats were given Naloxone 60 minutes after their concussions. 13 cats had serious concussions, and these cats were given no drugs after their concussions. The table below shows the blood flow to brain cells in each group of cats. Before having a concussion 45 minutes after the concussion 90 minutes after the concussion Cats with concussions that got Naloxone. Normal blood flowVery low blood flowNormal blood flow Cats with concussions that got no drug Normal blood flowVery low blood flow