The Brain and Trauma

The brain networks of trauma

The other day a friend told me a joke and it was one of the funniest jokes I have heard in a while. Laughter and full body explosions of joy overcame my body. I was laughing so hard I started to cry. Every worry or self-obsession I had up to that moment was completely lost. My physiology changed and the rest of the day and day after I was a great version of myself.

These shifts where we get out of ourselves are highly therapeutic.

Unfortunately in trauma-related disorders, we are often stuck in our our private world of thought intrusions, introspection, and internally focused.

So much that it is hard to be shifted out and focus on the “wow that is happening now”.

Trauma-related disorders seem to sit within three networked regions; The Default Mode Network, The Salience Network, and The Central Executive Network. We will go through each of these. As always, if you like this article; please make sure to like and subscribe

The Default Mode Network

The Default Mode Network (DMN) is a set of interconnected brain regions that are active during states of rest or quiet wakefulness.

The DMN brain regions are active during self-directed or internally focused mentation, and deactivate when engaging in externally oriented tasks.

It is active during internally focused states, such as self-reflection, autobiographical memory retrieval, mind-wandering, and thinking about the future; yet it decreases activity when focused on an external activity.

Alterations in the DMN in PTSD can manifest as difficulty regulating emotions, intrusive thoughts and memories, and a negative self-bias.

Meaning the DMN may be overactive leading to wandering, aimlessness, day dreaming where thoughts and memories become intrusive.

These disruptions may contribute to the persistent re-experiencing of traumatic events and the difficulty disengaging from negative thoughts and emotions.

The DMN is likened to an an operating system that runs behind the scene when the computer operator is idle.

It is doing tasks like updates, file repairs, and scans but it is not under the conscious control of the operator. Once the operator strikes the keyboard the focus of the operating shifts to the process at hand.

Now think of the DMN as a “chatterbox” as John Gabrieli; a neuroscientist and professor of MIT called it .

Imagine if your chatter is good… Think Stuart Smalley.

Then it is probably constructive.

Yet, imagine if your internal chatterbox was destructive.

A basic way to organize understanding the Default Mode Network is that there is a front half and back half.

The back half of the DMD is called the posterior cingulate and it facilitates your autobiographic memory; your personal history.

It allows us to think back, draw upon, and pick apart the past. When we ruminate about “should have, could have, would have’s” then we are in the back half of the DMD.

The front part is made of the medial prefrontal cortex . It works the opposite; allowing us to look forward and to think about and plan for the future. (Hallowell, Rately, ADHD 2.0 page 24)

My dear friend who passed way last year Dr. Trina Seligman used to say she knew when patients were healthy if they were planning ahead and thinking about the future. Makes a lot of sense.

Key components of the Default Mode Network include the posterior cingulate cortex, precuneus, dorsal medial prefrontal cortex (Brodmann’s areas 8/9/10), medial and lateral parietal cortex, medial and lateral temporal cortices, posterior cingulate cortex, and parts of the medial prefrontal cortex Huang (2024)Abbott et al., 2010; Abbott et al., 2011; Parker & Razlighi, 2019; Sheline et al., 2009; Li et al., 2010).

These regions play a pivotal role in supporting various cognitive processes related to self-referential thinking, episodic memory processing, and mind-wandering during periods of wakeful rest (Greicius et al., 2004; Callard & Margulies, 2014; Harrison et al., 2011).

A healthy DMN is vacillating between reflecting and planning head.

Whereas, in issues related to trauma we may stuck in the rumination, reflection, reliving, checked out, and in the past. I hope this doesn’t sound critical but rather clarifying as to what is happening in the mind of those with PTSD.

The Salience Network:

The Salience Network is central to processing cognitive and emotional dysregulation observed in PTSD. Meaning, it is central to detecting and filtering personally salient stimuli from the external world and within the body to guide behavior . The Network is compose of two key regions the Dorsal Anterior Cingulate Cortex (dACC) and the Frontoinsular cortex which is composed of the anterior insula and prefrontal cortex.

Dorsal Anterior Cingulate Cortex (dACC) is involved in a wide range of cognitive functions, including error monitoring, conflict resolution, and decision-making. Within the Salience Network, the dACC is thought to play a role in evaluating the salience of stimuli and signaling the need for attentional resources

The Frontoinsular Cortex: encompasses both the anterior insula and parts of the prefrontal cortex, forming a crucial hub within the Salience Network

The anterior insula is primarily involved in interoception, which is the awareness of internal bodily states, such as heart rate, breathing, hunger, and pain. It's also involved in processing emotions, particularly those related to disgust, pain, and empathy. The insula's role in detecting and integrating salient internal and external stimuli allows it to quickly shift attention to potentially significant events, whether they are happening in the environment or within the body

Prefrontal Cortex (PFC): The PFC is responsible for higher-order cognitive functions, such as planning, decision-making, and working memory.

The PFC's involvement in the SN likely relates to its role in evaluating the emotional significance of stimuli and guiding goal-directed behavior in response to salient event/

Some think of the Salience Network as a traffic controller; telling us to stop or go. These regions are involved in regulating emotional responses, and their dysfunction in PTSD can contribute to the difficulty controlling emotions and the fluctuating experience of hyperarousal and emotional numbing.

So the Salience Network is like a Traffic Controller where it:

1.Monitors the Environment

2. Directs Attention

3. Switches between Networks ( Default Mode Network), Central Executive Network-problem solving-goal oriented tasks)

4. Helps With Crisis Management

5.Balances Resources

When the Salience Network is imbalanced we observe:

1.Heightened threat sensitivity

2.Difficulty filtering out irrelevant information

3. Hyper Aware of potential threats and then emotionally numb or detached the next

The Central Executive Network (CEN):

The CEN involving regions like the dorsolateral prefrontal cortex and posterior parietal cortex) is responsible for goal-directed tasks, attention, and working memory. It becomes active during activities requiring focus, problem-solving, and decision-making.

When the DMN is active the CEN is off. This is called anti-correlated. This is a big point. So in self-referential thinking, daydreaming, and mind-wandering states the CEN is essentially shut off.

The CEN and DMN tend to suppress each other’s activity.

When a person is focused on a complex task requiring external attention, the CEN activates, and DMN activity decreases. Conversely, when a person is resting, daydreaming, or engaged in introspective thought, the DMN becomes active, and the CEN deactivates.

In a healthy state, this dynamic is crucial for cognitive flexibility. A balanced relationship between the CEN and DMN allows for a smooth transition between been reflection and goal oriented tasks. We need both.

In conditions like PTSD (and also depression, and ADHD) . An overactive DMN can make it hard for the CEN to engage fully, leading to issues with task focus and regulation of negative self-directed thoughts.

Every feel frozen and stuck. this is likely the dynamic.

Putting it all together:

The SN acts as a switch between the DMN and CEN by detecting salient stimuli and signaling which network should be prioritized.

I mean if the house is burning down; you aren’t going to sit and think about the past. You are going to get out.

This an extreme example; but understanding this lets you know how the SN, DMN, and CEN becomes disrupted in trauma and the symptoms that one has in PTSD may develop.

In future posts, I will explore interventions and techniques that will interface with these networks like EMDR, Meditation, Sound Therapy, Neurofeedback, Medications, Microdosing, and more.

I was recently blessed to have an interview with a trauma neuroscientist; Dr. Orli Peter. She is providing point of care trauma therapy in the Middle East caring for all backgrounds who have been dealing with the current war.

We speak about this and more below.

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