Negative Self-Appraisal and Brain Activity: Altered Function in Depression
Within the Default Mode Network (DMN) are three structures that link negative self-appraisal and brain activity:
- The medial prefrontal cortex (MPFC)
- The posterior cingulate cortex (PCC)
- And the inferior parietal lobule (IPL)
Negative self-appraisal refers to the relentless critical self talk that occurs in many people with depression.
Many patients report that this negative self talk can be so powerful that it blocks other cognitive function.
Activity in the default mode network (DMN) has a reciprocal relationship with many other aspects of cognitive function. Specifically, when performing externally directed tasks, the default mode network shuts down activity and there is some evidence that if this doesn’t happen then it interferes with the ability to perform those tasks.
The DMN is not just a “brain at rest” system. It has been shown to be involved in several non-externally focused activities such as self-awareness, self appraisal, and memory for past events. All of these are, of course, profoundly affected by depression.
Stronger influence of the medial prefrontal cortex on activity in two other areas of the default mode network is correlated with negative self appraisal in depression and also with reduced cognitive function.
Now researchers have shown that increased influence of the medial prefrontal cortex on activity in at least two parts of the DMN (the posterior cingulate cortex (PCC) and the inferior parietal lobule (IPL)) is strongly connected to increased negative self appraisal.
It’s as though the medial prefrontal cortex hijacks the default mode network to create an endless loop of negative self talk that gets in the way of other aspects of brain function.
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