Local suppression of alpha activity by pattern in half the visual field

Abstract

IF Lippold's hypothesis¹, that the alpha rhythm of the human electroencephalogram (EEG), (and perhaps other electrical signals that can be recorded from the scalp) are artefacts that result from eye movements, rather than genuine manifestations of neural activity, was found to be correct, it would seriously reduce the value of EEG and evoked potential techniques in research and clinical neurology. In the latter area, for example, considerable attention is being given to the validity of accepting an absence of EEG activity as a criterion of cerebral death. One of us (C. R. C.) has already discussed² earlier experiments that relate to the eye-movement hypothesis. We will describe here results that are consistent with a neural explanation for the control of alpha activity, but not with an eye-movement explanation.