Feedback electroencephalography techniques and clinical application

Abstract

A series of investigations into feedback training of the human electroencephalogram (EEG) is presented.
Firstly, a number of studies of methodological and theoretical issues, using feedback training of the 8-12 Hz occipital alpha rhythm as a paradigm, are reported. It 1s evident that some subjects are able both to suppress and to enhance their alpha activity from baseline levels; but, because individual differences are large, these training effects are difficult to demonstrate by the analysis of group data.
Secondly, an examination of the detection and feedback training of the 12-16 Hz, so-called, sensorimotor rhythm (SMR) in the rolandic EEG is described. The evidence for the existence of this EEG pattern in man is seen to be lacking. The techniques that are used to detect such EEG signals are demonstrated to have a crucial influence on the results obtained.
Thirdly, a clinical study to assess claims that SMR feedback training is an effective treatment for epileptic seizure disorders is reported. This study involved a comparison between feedback training of rolandic EEG in the SMR frequency range and several control procedures, using three adult patients each with a history of drug-resistant, generalised seizures. A marked clinical improvement for all three patients was obtained; but, although specific changes in the EEG did occur, this was not related to the training of any particular EEG component.
Some physiological mechanisms for the training and clinical effects observed in these studies are proposed.