O27 Wavelet analysis of EEG recorded during unconscious expectation of angry vs. neutral faces in patients with major depression and healthy controls

Objectives Patients with major depressive disorder (MDD) show attention bias to the negative emotional stimuli. We aimed at studying the EEG-correlates of unconscious expectation of angry human faces in MDD patients compared to healthy controls. Methods 128-channel EEG was recorded in MDD (23 female and 7 male) and in healthy volunteers (22 female and 8 male) while they categorized pictures as humans or animals. Half of the pictures were neutral and half were showing the faces of angry humans or animals. The pictures were preceded by cues (one for each category), which meaning was not explained to the participants. We performed the wavelet analysis of EEG recorded during the face expectation period: 1000–2000 ms from the cue onset. Results We found the emotional modulation (EM) in EEG rhythms during the expectation of angry vs. neutral faces in both groups. Statistical comparison of the spectral power using 2 × 2 factorial design showed that the EM differences ( p Discussion The unconscious expectation of angry vs. neutral faces resulted in EM differences between the MDD and healthy controls in the right frontal and bilateral parietal areas mostly in beta range, and also in alpha and gamma. Conclusions The EEG from the parietal locations can be a better indicator for the differences between MDD and healthy controls. Significance Unconscious emotional processing in patients may become a prospective biomarker for depression.