The effects of electrode placement upon EEG biofeedback training: the monopolar-bipolar controversy.

Roles of tradition, convenience, and noise or artifact rejection are discussed with regard to the monopolar versus bipolar electrode placement controversy in electroencephalography (EEG). Particular emphasis is placed on the relevance to biofeedback. The crucial interactions between the differential amplifier, brain waves, and monopolar/bipolar placements are discussed. Through logical analysis and empirical observation, it is demonstrated how the very nature of the EEG's differential amplifiers must destroy those elements of brain activity which are common to the recording electrodes. Controlled experiments further illustrate the critical importance of electrode placements. Various methods, including preferred electrode placements, are presented to help resolve recording problems that frequently arise. It is concluded that there are serious implications for researchers, EEG clinicians, biofeedback providers, and their clients in preferring one type of electrode placement technique over the other. EEG recording accuracy is affected by this choice.