Even though high-resolution CSD measures were crucial for the present study, we also submitted a reduced-electrode CSD montage to fPCA, resulting in significant findings (Section S4 in the Supplement). In addition, nose-referenced EEG power spectra were analyzed at standard 10–20 system sites to provide a bridge to the literature using conventional “low-resolution” EEG in alpha and theta bands. Although group differences in alpha showed trends consistent with those reported for CSD measures, they were not statistically significant and alpha asymmetry did not differ between groups (Section S5 in the Supplement). However, an ANOVA of EEG theta revealed one significant group effect: a Group × Condition × Electrode interaction in which the slope of the anterior-to-posterior increase in power for eyes-closed (i.e., also seen in maps at low-alpha/theta frequencies; Figure S5 in the Supplement) was flatter in nonresponders (Figure S6 in the Supplement).
