The Default Mode Network and PTSD

Posttraumatic Stress Disorder can be a debilitating disorder to live with, characterized in part by hypervigilance and reduced filtering of sensory input to the brain. Research has been focused on how treatment can center on regions of the brain involved in PTSD to improve symptoms in those with the disorder. 

In the research article entitled "Posttraumatic Stress Disorder Is Associated with a Dysrhythmia across the Visual Cortex and the Default Mode Network," Clancy et. al. hypothesized that there is an association between a decrease in alpha activity and the ability to filter out sensory input in the default mode network. The DMN is principally involved in the activity of the resting brain, with alpha activity being the resting brain's dominant electrical component. The researchers found deficits in alpha activity in participants with PTSD, correlating with symptoms of hypervigilance. This decreased activity is associated with lessened visual cortical inhibition, contributing to the lack of filtering sensory input. These findings support the targeting of alpha stimulation in the visual-cortex-DMN system in treatment of PTSD.

Another instance of PTSD and DMN correlation is explored in the article “Default mode network abnormalities in posttraumatic stress disorder: A novel network-restricted topology approach.” The default mode network comprises many other areas, including the ventromedial and dorsomedial prefrontal cortices and the posterior cingulate cortex. It is a main network in the area of intrinsic connectivity networks (ICNs), or areas that couple to serve spatial functions. The article details the importance of developing studies to research ICN involvement in psychiatric disorders. This study sought to explore connectivity in the DMN, specifically in its involvement with PTSD. They hypothesized that PTSD symptoms are associated with decreased functional connectivity in the DMN. Using neuroimaging and anatomical connectivity, the researchers studied symptoms in veterans and found reduced DMN connectivity in those with high severity of symptoms. 

Both articles focused on the region of the brain involved with resting activity, the default mode network. While the first article centered on correlation of alpha activity with symptoms, the second focused on functional connectivity in the region in association with symptoms. In both studies, results indicated a lower connectivity and function in the DMN. This contributes to the hypervigilance and general anxiety associated with PTSD. When an individual's general resting state is disturbed, anxiety and stress can emerge, disrupting the quality of life. The importance of developing proper and region-specific treatment of PTSD symptoms is heavily stressed in both articles. There are many different ways to target these integral regions to lessen stress and hypervigilance.

References: 

1. Teddy J. Akiki, Christopher L. Averill, Kristen M. Wrocklage, J. Cobb Scott, Lynnette A. Averill, Brian Schweinsburg, Aaron Alexander-Bloch, Brenda Martini, Steven M. Southwick, John H. Krystal, Chadi G. Abdallah, Default mode network abnormalities in posttraumatic stress disorder: A novel network-restricted topology approach, NeuroImage, Volume 176, 2018, Pages 489-498, ISSN 1053-8119, https://doi.org/10.1016/j.neuroimage.2018.05.005.

2. Kevin J. Clancy, Jeremy A. Andrzejewski, Jessica Simon, Mingzhou Ding, Norman B. Schmidt and Wen Li, Posttraumatic Stress Disorder Is Associated with α Dysrhythmia across the Visual Cortex and the Default Mode Network, eNeuro 20 July 2020, 7 (4) ENEURO.0053-20.2020; DOI: https://doi.org/10.1523/ENEURO.0053-20.2020