Fig. 4

Associations of PSD and PC loadings of the four putatively physiologic factors (1, 3, 4, and 5) with physiological (aging) and pathological (slowing, epileptiform activity) variables. Factor numbers correspond to those in Fig. 3. Loadings describe activity found in eyes-closed awake EEG segments selected from expertly graded routine EEGs in the population-level dataset. (A) Correlations of PSD and PC loadings of normal EEGs with patient age. (B) Correlations of PSD and PC recording loadings with expert-assigned severity of slowing. The ranked severity levels are 0 (normal EEG, no slowing), 1 (Dysrhythmia 1 EEG, mild slowing), and 2 (Dysrhythmia 2 EEG, moderate to severe slowing (C) Correlations of PSD and PC recording loadings with the presence of epileptiform activity (Dysrhythmia 3 EEGs abbreviated as “Dys3”). Significance levels correspond to the Mann-Whitney-Wilcoxon test. Loading values along y-axes are in arbitrary units. * indicates a significant correlation with p < 0.05 and **** indicates a significant correlation with p < 1e-4.