Multiple monopolar electrical contacts are applied to the scalp or body, using other points on the body as reference and ground. The brain muscle or other bioelectric waves conducted from each contact, relative to the reference point, are amplified, filtered, and instantaneously analysed to produce a...http://www.google.fr/patents/US3978847?utm_source=gb-gplus-shareBrevet US3978847 - Multiple channel phase integrating biofeedback computing method
