Low-frequency oscillations in the alpha and theta range have also been associated with default mode network (DMN) activity (e.g, Scheeringa et al., 2008; Laufs et al., 2006), and group differences in top-down control may also be related to differences in DMN activity. However, it is not likely that mere differences in DMN activity account for the observed group differences in alpha ERD. Firstly, there were no group differences in baseline power of theta/alpha, which would be expected to directly reflect DMN activity. Secondly, alpha ERD was clearly dependent on condition, that is, it was most prominent for targets that required an active response, less present for novels that required a response inhibition, and virtually not present for nontargets. Clearly, further research is required to delineate the underlying mechanism of alpha ERD reduction in schizophrenia and CHR patients.
