Effects of Exercise on Memory in Healthy and Brain-Injured Individuals

Background: \- Research has shown that one exercise session may improve a person s ability to recall information they learned before the exercise. Knowing how exercise changes brain activity to improve memory can help researchers understand how memory works and how to improve it in people with memory problems. This study compares two kinds of exercise on a stationary bike for their ability to temporarily improve memory on certain tests. Researchers will look at the effect of exercise on body chemistry by drawing blood and collecting saliva. Objectives: \- To understand how a single session of exercise affects memory testing in healthy people and people who have had traumatic brain injury (TBI). Eligibility: * Adults ages 18 through 45 with TBI. * Healthy adult volunteers, ages 18 through 45. Design: * Participants will be screened with medical history and physical exam. This will take about 1 hour. * Participants with TBI will also be screened with a test of their memory. This will take another hour. * Visit 1 will take about 3 hours. Participants will: \- Have a tube inserted in their arm for drawing blood during the tests. \- Take memory tests. They will look at pictures, symbols, and words, then answer questions. \- Give a saliva sample by chewing on a small sponge for 2 minutes. \- Exercise on a stationary bike. \- Take the memory tests again. \- Visit 2 will take place 1 week later. Participants will take the memory tests only.