A cap worn by the user relayes electrical impulses from the brain to an on-board computer that analyzes them almost instantly and transmits commands controlling the chair in order to move it forward or turn it. The wheelchair isn't quite so easy to stop, however: Its user must inflate one cheek to trigger it to halt.
http://www.disaboomlive.com/Blogs/saydrah/archive/2009/06/29/toyota-unveils-thought-powered-wheelchair-controlled-by-user-s-brain-waves.aspx
