As we have seen from many other articles that I have posted on this site, those suffering from PTSD/Complex PTSD frequently have, amongst others, the following symptoms:

In a recently published journal article, Chan (2016) states that whilst these deficits have been attributed most frequently to a dysfunctional amygdala and a dysregulated neural fear system, other brain systems are also involved. 

Chan (2016), in his article, focuses on one other such neural system:

•  The DEFAULT MODE NETWORK (DMN).

Although it is still under debate as to exactly which brain structures make up the DMN, it is generally considered to include:

• the medial prefrontal cortex
• the posterior cingulate cortex
• the inferior parietal lobule

What Are The Functions Of The DMN?

The term ‘default mode network’ and its general concept were first introduced by Raichle et al. (2001)

It is theorized that the DMN is a brain system made up of various structures (see above) which is active when an individual is not paying attention to the outside world and not undertaking any specific mental task (e.g. when daydreaming).

Research also suggests the DMN is active when:

• we are thinking about ourselves, including autobiographical recall, self-reflection, and self-referential processing

• we are thinking about others and involved in social cognition

• we are thinking about the future and involved in prospection (visualizing, predicting and evaluating various futures for ourselves including future emotional responses to particular scenarios and planning).

• we need to exercise moral sensitivity (the term ‘moral sensitivity’ refers to the ability to identify existing moral issues and understand the moral consequences of particular actions and decisions).

Chan (2016) found that trauma damages the DMN, impairing its ability to function, including the five functions listed immediately above. and leading to, amongst other problems, a fragmentary sense of self and others.

In fact, the DMN appears to be negatively affected by trauma in terms of its volume (its size is diminished), the interconnectivity of its components (these connections become weakened), and its level of activity (its level of activity is reduced).

As a result of this impairment, Chan asserts, the brain goes into a TRAUMATIZED RESTING STATE.

 

According to a meta-analysis of relevant research conducted by Saskia et al. (2016), this aberrant resting brain state and the associated altered neural activity patterns may, in addition to neurological deficits already mentioned above,  reflect:

However, the researchers also state that this area of research is still not fully clear and that further research into it is therefore necessary.

Other research (e.g. Akiki, 2018) has suggested that this altered brain state in individuals with PTSD is linked to an impaired ability to form healthy attachments.

There is evidence that a damaged DMN is also associated with other disorders including major depression, schizophrenia, and autism.

References:

Akiki, Teddy J.; Averill, Christopher L.; Wrocklage, Kristen M.; Scott, J. Cobb; Averill, Lynnette A.; Schweinsburg, Brian; Alexander-Bloch, Aaron; Martini, Brenda; Southwick, Steven M.; Krystal, John H.; Abdallah, Chadi G. (2018). "Default mode network abnormalities in posttraumatic stress disorder: A novel network-restricted topology approach".

Buckner, R. L.; Andrews-Hanna, J. R.; Schacter, D. L. (2008). "The Brain’s Default Network: Anatomy, Function, and Relevance to Disease". Annals of the New York Academy of Sciences. 1124 (1): 1–38. Bibcode:2008NYASA1124….1B. CiteSeerX 10.1.1.689.6903. doi:10.1196/annals.1440.011. PMID 18400922. S2CID 3167595.

Chan The fragmentation of self and others: The role of the Default Mode Network in post-traumatic stress disorder. Published 2016

Raichle ME, MacLeod AM, Snyder AZ, Powers WJ, Gusnard DA, Shulman GL. A default mode of brain function. Proc Natl Acad Sci U S A. 2001;98(2):676-682. doi:10.1073/pnas.98.2.676

Saskia B. J. Koch M.Sc.,Mirjam van Zuiden Ph.D.,Laura Nawijn M.Sc.,Jessie L. Frijling M.Sc.,Dick J. Veltman M.D., Ph.D.,Miranda Olff Ph.D.ABERRANT RESTING-STATE BRAIN ACTIVITY IN POSTTRAUMATIC STRESS DISORDER: A META-ANALYSIS AND SYSTEMATIC REVIEW First published: 25 February 2016 https://doi.org/10.1002/da.22478

David Hosier BSc Hons; MSc; PGDE(FAHE).