Depressive Symptomatology and the Activity of Oscillatory Resting State Networks

Abstract

Depression is among the commonest mental illnesses associated with changes in the emotional domain and the function of the brain’s default mode network (DMN). The aim of the present work was to identify differences in the emotional tone of spontaneous thoughts linked with depressive symptomatology and the activity of the brain’s oscillatory networks identified by source localization combined with independent component analysis. The severity of depressive symptomatology correlated positively with a predominance of negative emotions during recording and with δ and θ activity in the orbitofrontal cortex and negatively with θ activity in the posterior center of the DMN. As an increase in the power of low-frequency oscillations in the orbitofrontal cortex was seen in aversive states and the decrease in their power in the DMN is evidence of increased activity in this system, linked with self-evaluation processes, our results lead to the conclusion that the predisposition to depression is characterized by a general negative emotional disposition and an extreme focus on the self.