The default mode network and self-referential processes in depression

Summary & key facts

Researchers looked at a brain network called the default mode network, which is active when people think about themselves. They asked people with major depression and people without depression to look at negative pictures and to try to reframe them. People with depression showed a failure to quiet down parts of this self-focused network while viewing and rethinking the pictures, and they showed bigger reactions in emotion and memory areas. The results suggest that depression involves both stronger reactions to negative things and a reduced ability to turn down self-focused brain activity, which could help explain why people with depression get stuck in negative self-thoughts.

Key facts:

• The default mode network is a group of brain areas that tend to be active when people reflect on themselves or are not focused on an outside task.
• In people without depression, activity in this network usually drops when they do focused, goal-directed tasks.
• The study compared people with major depression to people without depression while they passively viewed negative pictures and while they actively reappraised those pictures, meaning they tried to think about them in a different way.
• People with depression failed to reduce activity in several parts of the default mode network during both viewing and reappraising negative pictures. These parts included the ventromedial prefrontal cortex, the anterior cingulate, lateral parietal cortex, and lateral temporal cortex.
• Viewing negative pictures caused a larger increase in activity in emotion and memory-related areas such as the amygdala, parahippocampus, and hippocampus in people with depression than in people without depression.
• The authors say these findings point to two related features in depression: stronger stimulus-driven brain responses and a reduced ability to down-regulate, or turn down, self-focused network activity. This gives a brain-network framework for thinking about how depression affects self-referential thoughts.

Abstract

The recently discovered default mode network (DMN) is a group of areas in the human brain characterized, collectively, by functions of a self-referential nature. In normal individuals, activity in the DMN is reduced during nonself-referential goal-directed tasks, in keeping with the folk-psychological notion of losing one's self in one's work. Imaging and anatomical studies in major depression have found alterations in both the structure and function in some regions that belong to the DMN, thus, suggesting a basis for the disordered self-referential thought of depression. Here, we sought to examine DMN functionality as a network in patients with major depression, asking whether the ability to regulate its activity and, hence, its role in self-referential processing, was impaired. To do so, we asked patients and controls to examine negative pictures passively and also to reappraise them actively. In widely distributed elements of the DMN [ventromedial prefrontal cortex prefrontal cortex (BA 10), anterior cingulate (BA 24/32), lateral parietal cortex (BA 39), and lateral temporal cortex (BA 21)], depressed, but not control subjects, exhibited a failure to reduce activity while both looking at negative pictures and reappraising them. Furthermore, looking at negative pictures elicited a significantly greater increase in activity in other DMN regions (amygdala, parahippocampus, and hippocampus) in depressed than in control subjects. These data suggest depression is characterized by both stimulus-induced heightened activity and a failure to normally down-regulate activity broadly within the DMN. These findings provide a brain network framework within which to consider the pathophysiology of depression.

Topics

Functional Brain Connectivity Studies Mental Health Research Topics Neural dynamics and brain function

Categories

Cognitive Neuroscience Life Sciences Neuroscience

Tags

Amygdala Anterior cingulate cortex Brain activity and meditation Cognition Cognitive psychology Cortex (anatomy) Default mode network Depression (economics) Economics Electroencephalography Functional connectivity Macroeconomics Neuroscience Posterior cingulate Prefrontal cortex Psychology Stimulus (psychology) Ventromedial prefrontal cortex

Conditions & symptoms

Depression Lack of energy or motivation Sadness or low mood