The identified alpha subbands, and an absence of a distinct theta, are consistent with the findings of Shackman et al (57), based on a spectral factor analysis of common-average EEG. These investigators suggested that alpha subbands provide no advantage over the broader alpha band in describing differences related to temperament or task demands. Although the two CSD-fPCA factors likewise do not differentially predict treatment response, there is no a priori rationale for generalizing to other clinical or physiological classifications. It should also be noted that these findings discount the possibility that a simple shift between two distinct spectral components is involved (e.g., alpha-slowing).
