Figure 1.

Schematic description for a BMI that relies on the real-time sampling and processing of large-scale brain activity to control a robotic prosthetic arm. Multiple, chronically implanted, intracranial microelectrode arrays are used to sample the activity of large populations of single cortical neurons simultaneously. The combined activity of these neural ensembles is then transformed by a mathematical algorithm into continuous three-dimensional arm-trajectory signals that can be used to control the movements of a robotic prosthetic arm. A closed control loop is then established by providing the subject with both visual and tactile feedback signals generated by movement of the robotic arm. Reprinted with permission from Macmillan Publishers Ltd: Nature 409, 403–407 (Nicolelis, 2001), copyright 2001.