Major Depressive Disorder (MDD) is a clinically and neurobiologically highly heterogenous mood disorder that consists of a variety of symptom clusters including mood symptoms, physical symptoms, and cognitive symptoms. While the traditional model of depression implicates mood as the primary symptom cluster, a more recently published conceptual understanding of depression has extended to also include cognitive symptoms. Moreover, the understanding of the central role of cognitive processes in emotion processing, social interaction, and pure cognitive performance has led to a model suggestion...