The force of a hit can cause a concussion on the part of the brain that was directly hit or on the opposite side of the brain (as the brain tissue itself moves from the force of the blow and hits the opposite side of the skull).
Different areas of the brain control different functions, so blows to your head can predict your symptoms. A concussion to the back of the brain causes balance issues, fogginess, neck pain and difficulty concentrating. These symptoms usually predict a longer recovery from a concussion.