I took a course in the brain last year and learned some fabulous facts. Your brain weighs 2 to 3 pounds, less than two percent of your body weight. I bet you would never guess how many calories this mass of curlicues in your head burns in 24 hours. You need around 2000 calories a day to maintain your body weight.
You can find the answer here:
The Brain is a Calorie Burner
Following are other items on the nature and function of your brain and the relevance of exercise to a healthy brain:
WebMD has a fun quiz on the brain you can take here.