The document discusses the Brain Gate system, which is a brain implant that implements brain-computer interface (BCI) technology. It describes how BCI research first used implants in rats and monkeys to detect brain signals that could operate devices. The Brain Gate system was then developed for human use, allowing a paralyzed man to control a computer using only his thoughts. The document outlines the principles, components, applications and limitations of BCI technology, suggesting it has potential to help disabled individuals but requires more development of accurate and safe brain sensors.