Brain-activated computer system. Disabled boy in a wheelchair using a brain-activated system to play a computer game with his friend. A MindDrive sensor (black, not clearly seen) on his finger monitors his mental activity. This is done by measuring electrical signals in his skin, along with his heartbeat, temperature and blood pulse volume. A computer program filters out unconscious nerve impulses and only responds to conscious signals. It is hoped that MindDrive will allow more complex computer software to be operated. The system can also be used to show the mental states of people who cannot describe them themselves, for example babies and patients during surgery.