Simultaneous EEG + fMRI study of brain activity during an emotional Stroop task in individuals in remission from depression

Individuals in remission from depression (MDDR) tend to experience lingering cognitive and emotional processing alterations. However, little is known about the neural profiles underlying these features. Using simultaneous EEG+fMRI, we assessed neural profiles during the emotional word Stroop task (eStroop) in people with MDDR and healthy volunteers (HVs). Event-related potentials (ERPs) were extracted (N450, N2 & P3). Assessments of brain activation, as modulated by ERPs, were carried out, as were fMRI-informed ERP analyses. A trend for greater P3 amplitudes in MDDR versus HV groups existed. HV versus MDDR groups had greater brain activation to emotional versus neutral words in various regions, including the left amygdala, inferior frontal gyrus (IFG); this appeared to be driven by elevated activity to neutral words in the MDDR group (neutral > emotional). HVs showed greater activation (emotional > neutral) modulated by N450 amplitude in various regions, while MDDRs showed greater neutral > emotional activation modulated by N450 amplitude in the left IFG and left precuneus. Our EEG+fMRI findings indicate that people with MDDR appear to have blunted neural differentiation to emotional versus neutral stimuli or elevated neural responses to neutral information processing. This might represent altered neuronal processing (i.e., underlying attention and conflict processing) during a cognitive task with an emotional component in individuals remitted from depression, or elevated neural responses to ambiguous or neutral information. In sum, subtle lingering neuronal features not accompanied by performance differences appear to exist in people with MDDR.