No consistent relationships between oscillations and latencies of visually and auditory evoked EEG potentials and measures of mental performance.

Abstract

In this study, the hypothesis was tested whether there is any relationship between measures of intelligence and working speed on the one hand, and characteristics of visually or auditory evoked EEG potentials, on the other. The study was performed on two samples: 1. In 236 University students selected for presence of four different, inherited EEG variants, product-moment correlations were computed between test scores for various aspects of mental performance on the one hand, and two measures of averaged visual and auditory evoked EEG potentials (VEPs and AEPs), on the other. The two EP measures were the average latency of all identifiable peaks between 70 and 600 ms after stimulation; and the "oscillation", a combined measure of amplitudes, comparable to Hendrickson's "string measure". Moreover, correlations were computed between two selected test scores (IQ and Raven) on the one sides, and the amplitudes and latencies of the components named P1, N1, and P2 by Buchsbaum on the other. 2. Twenty-four adults with mental retardation of unknown origin, inmates of an institution for the mentally retarded, were compared with 19 normal controls matched for age and sex - there were no consistent positive correlations between the characteristics of VEPs and AEPs and any of the performance measures studied. Hence, the hypothesis that there are consistent correlations between oscillation and latency of EPs and measures of mental performance was not confirmed. There is no convincing overall explanation for the discrepancies between various results reported in the literature but some of them may be explained either by individual differences in EEG maturation among children, or by additional sensoric input in some series, or by admixture of subjects with organic brain damage in some of the series, or by the individual characteristics of the resting EEG - a parameter that had been neglected in all previous studies.