<human>:  How does a concussion affect the brain?
<bot>: A concussion is a type of traumatic brain injury. It is caused by a blow to the head that causes the brain to move back and forth inside the skull. This can cause damage to the brain cells. Symptoms of a concussion can include headache, dizziness, confusion, memory loss, and difficulty concentrating. In some cases, a concussion can lead to more serious injuries, such as a skull fracture or bleeding in the brain.