The technical, neurological and psychological significance of 'alpha', 'delta' and 'theta' waves confounded in EEG evoked potentials: a study of peaklatencies

It is suggested that lack of progress in understanding the neurological and psychological significance of EEG averaged evoked potentials (AEPs) and ev ent related potentials (ERPs) may be due to the confounding of, 'delta', 't heta' and 'alpha' frequency responses generated by the 'brain-stem' 'limbic ' and 'thalamic' cortical activating systems, respectively. This hypothesis was tested in a sample of 93 adults by recording EEG responses to auditory tones and using narrow-band filters to distinguish '4 Hz', '7 Hz', and '10 Hz' component waves in the unfiltered AEP. Bivariate and multivariate stat istical analyses of peak latencies provided evidence of the distinct and un itary nature of these component waves and demonstrated their relative influ ence on the P1, N1 and P2 peaks of the unfiltered AEP. The results also rev eal a predicted negative relationship between the 10 and 4 Hz latencies whi ch is attributed to inhibition of the delta frequency brain-stem ascending reticular activating system (BSARAS) by the alpha frequency diffuse thalami c projection system (DTPS). Correlations of the 4 Hz latencies, with age, s ex, and behavioural arousal variables confirm that the 4 Hz latencies are a ssociated with the maintenance of behavioural arousal, an important functio n of the BSARAS. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved .