Signals produced by brain activity are measured by each sensor of an array of magnetic and/or electrical sensors external to but proximate to the head (or other portion of the body) of a subject. The measurements obtained simultaneously from all of the sensors are combined in a manner to permit selective...http://www.google.com/patents/US4977896?utm_source=gb-gplus-sharePatent US4977896 - Analysis of biological signals using data from arrays of sensors
