Understanding the relationship between default network activation and connectivity, depression, and maladaptive cognition

Abstract

The default network (DN) and its functions in healthy individuals have been identified using a convergence of data from numerous neuroimaging and behavioral studies. In this dissertation, I similarly conducted a series of behavioral, neuroimaging, and brain stimulation studies to better understand the DN across the clinical course of depression and its role in cognitions associated with depression. In our neuroimaging studies, we investigated DN activity after being exposed to negative versus positive self-referential stimuli (critical versus praise comments) across at-risk (i.e., females with high levels of neuroticism), currently depressed, and recovered depressed individuals. In a behavioral mind-wandering study, we explored the specific types of maladaptive thoughts that are triggered by criticism in individuals with depressive symptoms. In a transcranial direct current stimulation (tDCS) study, we tested whether changing criticism-specific DN activity corresponded with changes in the specific kinds of maladaptive thoughts identified in the behavioral mind-wandering study. This series of studies suggest that criticism-specific DN hyperactivation is present to varying degrees across depression, regardless of current symptom status, that criticism-specific DN activity could be supporting maladaptive thinking in depression, and that this pattern of thoughts can be changed by changing DN activity.