Figure 5. From input over regions and networks to contents in awareness.

(A) ‘Normal’ balance between default-mode network (DMN) and executive network (EN) in healthy subjects. Lower part: The figure illustrates schematically the relationship between regions (lower part; PACC: Perigenual anterior cingulate cortex; DLPFC: dorsolateral prefrontal cortex) and their respective input (PACC: stronger internal input from own body and thoughts; DLPFC: stronger external input from environment). Upper level: the PACC is the core region of the default-mode network (DMN) as visualized in the brain on the left while the DLPFC is the core region of the executive network (EN) as visualized in the brain on the right. Like PACC and DLPFC both networks, DMN and EN, stand in a reciprocal relationship to each other as signified by the negative sign symbol. The balance between DMN and EN mediates the balance between internal and external mental contents in our awareness which can be described as self-focus and environment-focus. (B) Dysbalance between default-mode network (DMN) and executive network (EN) in MDD. The mechanisms described in the healthy brain in panel A are altered in MDD. There is a dysbalance on the input level with decreased input to DLPFC which in turn implies (relatively) increased internal input in PACC. This dysbalances PACC and DLPFC and subsequently alters the balance between DMN and EN, in turn, abnormally increasing internal mental contents leading to an increased self-focus while, at the same time, external mental contents are decreased with a decreased external environment-focus.