New Scientist TV: Punk rock skeleton demos mind control system: In the video above, a skeleton with a mohawk is helping to visualise how a new neural implant device reads brain signals and interprets them to control a prosthetic arm. The yellow spikes radiating from the skeleton's head represent the firing of motor neurons in the brain. Each neuron is tuned to recognise a different direction in space, so as the arm moves, the spikes change to reflect the changing direction. By adding together the output of all the neurons, the direction of the arm's movement - represented by the blue arrow - can be predicted.
...This system, developed by Daniel Moran of Washington University in St. Louis uses a grid of disc-shaped electrodes, inserted between the brain and the skull, to read electrical activity in the brain. It's more precise than electrodes placed outside of the skull, and less invasive than probes inserted into the brain itself.