A concussion is classified as a type of traumatic brain injury. It occurs when the brain moves rapidly back and forth due to direct or indirect force to the head or body, with or without loss of consciousness. At each extreme of movement, your brain tissue experiences an impact as it comes in contact with your skull. This rapid movement causes brain tissue to stretch and injure brain cells (called neurons), resulting in the sudden release of neurotransmitters. This uncontrolled flood of neurotransmitters causes chemical and metabolic changes all around your brain, making it difficult for cells to function and communicate properly. The result is a decrease in brain function and the onset of symptoms commonly associated with concussion.