Prototype #2 for FND Functional neurological disorder (FND) describes a problem with how the brain receives and sends information to the rest of the body. It's often helpful to think of your brain as a computer. In someone who has FND, there's no damage to the hardware, or structure, of the brain. It's the software, or program running on the computer, that isn't working properly. The problems in FND are going on in a level of the brain that you cannot control. It includes symptoms like arm and l