A brain implant is a small device that doctors can put in a person's head to help them with certain medical conditions. The device works by connecting to and controlling parts of the brain to provide treatment or send signals. For example, some brain implants are used to treat Parkinson's disease, epilepsy, and depression. They can also be used to help paralyzed people improve their mobility or help blind people to see better. The device works by sending electrical signals to the right parts of the brain, and can help to reduce or stop seizures, or improve movement.