Auditory Evoked Potential Variability in Schizophrenia

Variability of the individual brain wave potentials comprising an auditory averaged evoked potential (AEP) is greater for schizophrenic than for normal subjects. In schizophrenics this increased AEP variability results in fewer similarities, and therefore lowered correlations, between two AEPs evoked by tones of the same pitch. Thus, the increased difference between AEPs to tones of two different pitches found in schizophrenia seems to be a function of increased AEP variability. This increase of AEP variability in schizophrenic patients reflects response variability and is not principally the result of increased background EEG variability. AEP standard deviation is highly correlated with AEP amplitude, and methods of correcting for this are discussed