Abstracts

Rationale: Characteristics of the normal EEG posterior dominant rhythm (PDR) were described before the modern era of computing and digital EEG acquisition. For instance, conclusions were based on a few seconds of EEG data, and power spectral analysis could not be performed. As part of an ongoing longitudinal study on exercise and emotion in healthy adolescents, we were able to analyze maturation of EEG PDR spectral characteristics in a homogeneous cohort of subjects.Methods: Thirty-one carefully screened, healthy 14 and 15 year-olds underwent a resting wake EEG, with a follow-up study exactly one year later. Fast Fourier transform in the 8 – 13 Hz band was performed on two minutes of continuous eyes-closed EEG signal at electrode derivations T5-O1 and T6-O2. The resulting power spectra were divided qualitatively into three categories: single-peak, double-peak, and multi-peak, and a simple algorithm was developed to calculate a single posterior dominant frequency for each hemisphere. The mean of these two frequencies was taken as the overall PDR frequency.Results: Mean age at the two EEGs was 15.2 and 16.2y respectively. Mean PDR frequency on the left and right sides was 10.1 Hz for both the first and second EEGs, and thus the mean overall PDR frequency was also 10.1 Hz for both studies. About half of the spectral patterns were single-peak, and the remainder were divided about equally between double-peak and multi-peak. There was a high correlation between the left and right PDR spectral pattern within each EEG, but poor correlation between EEGs of the same subject over time.Conclusions: PDR frequency does not change between age 15 and 16. PDR spectral characteristics are often more complex than previously assumed, but are unlikely to be an invariant feature of an individual's EEG. Hemispheric asymmetry of alpha band power may occur during a two-minute segment of EEG. (Supported in part by NICHD RO1HD037746, K23NS46347, MO1RR00827-S1)