IN his report “Alpha Rhythms in the Hyperkinetic Child”1, Shetty attempts to define the neurophysiological substrate of hyperkinesis by interpreting drug-induced variations in the alpha rhythms of the human electroencephalogram (EEG). Such an attempt presumes knowledge of the origin of alpha rhythms, but the single article2 to which Shetty refers, and which is said to allege that “alpha rhythms represent an inhibitory process involving discharge of sub-cortical influences back into the cortex, and effecting the termination of cortical excitation associated with automatization or habituation of learned behaviour”, in fact contains no evidence on such physiological processes. It refers in turn to an earlier physiological observation—the so-called “recruiting response” in cats3, which may or may not have any connexion with human alpha rhythms.