Simultaneous EEG and fMRI investigation of frontal alpha power and frontal alpha asymmetry in young adults with a history of major depressive disorder.

Major Depressive Disorder (MDD) is one of the leading contributors to global disability and burden of disease. Resting frontal alpha asymmetry is a promising risk indicator for MDD, regardless of clinical status, and neuroimaging literature has supplied evidence supporting MDD as a network disorder. However, the nature of the relationship between frontal EEG asymmetry and underlying neural systems in MDD remains unclear. Simultaneous resting EEG and fMRI were collected from 51 euthymic participants (30 female, age range: 18-25 years, 27 Hx + for MDD) to examine 1) EEG-fMRI dynamics in resting-state networks between and within-subjects and 2) the role of alpha asymmetry and midfrontal alpha power in BOLD activation in depression-related ROIs. A consistent pattern of negative correlations was found between midfrontal alpha power at sites superior to the dorsal nexus (Sheline et al., 2010) and BOLD signal connectivity in the right cognitive control network in the bilateral IFG, insula, IPL, and MFL. MDD history was a significant factor in the relationship between F6/F5 asymmetry and connectivity in the default mode network. It was also a significant moderator of activity in the ACC, PCC, right IPL, and left caudate, with a positive Hx + correlation and a negative Hx- correlation. These findings are consistent with current understanding of alpha activity as inhibitory to network synchronization, support the dorsal nexus as an area for further investigation, and point to MDD history as a promising moderator of EEG-fMRI dynamics.