Post Traumatic Stress & The Brain~


When the nervous system perceives the attack, the limbic system (containing the amygdala) within milliseconds plans to fight, flight, or freeze. The nervous system also has a role, but we will focus on the brain first.

The two most important areas of the brain involved in threat are: the Amygdala and Hippocampus. The Thalamus also plays a role in that it keeps track of sensory information.

The Amygdala which is part of the brain living in the limbic system,  is to control all emotions and body sensations moving the brain into a  fight, flight, and freeze response.

The Hippocampus is a part of the brain’s whose  job it  is to record facts and memories, as well as the time and sequence of the event.

When the nervous system is under threat, some things happen in the body to prepare for an attack, one of these things being hormones, like norepinephrine and cortisol rising in the body, and causing the  Amygdala part of our brain to go into threat mode.

When the Amygdala part of the brain is under threat, it takes over the mind and can be described as overriding the Hippocampus  (responsible for memory, time and sequence of events).

Since the Hippocampus is responsible for  recording memory, time, and sequence of events, it makes sense that many people will explain that after the threatening  event, they cannot remember the entire memory/incident, or they only remember the incident in fragments, or they see the event disorganized in terms of sequence and they experience these fragmented memories in flashbacks. Without a time frame, beginning, middle and end,  your brain can sometimes think the trauma did not end. This is why many people speak about the event with little relief. Instead they start to  ruminate about the event.  It could be hypothesized that this is the brains way of trying to make sense of it or put it away in a file system within the brain. Some people find that they are continually triggered (past is in the present) either through sounds, smells, or internal sensations that remind them of the original threatening event.  When triggered, a person may act as if the threat is in the present by either fleeing, fighting, or freezing. This can be quite embarrassing if there is no danger in the present.

It’s as if the Hippocampus has not been able to defragment (like a computer). Put another way, even though the event may be over, the Hippocampus still needs to  process the incident/memory, which is why many people continue to have nightmares, night terrors, flashbacks, or cannot remember the event, but have a sense of the event either through smell, taste, sounds, or sight.

When a traumatic/threatening event has not been processed what can sometimes happen is that any trigger (like an internal sensation such as butterflies in the stomach, dry mouth, nausea, can send a signal to our Amygdala which then starts the cycle all over again. The Amygdala believes it’s under threat and sets the system up for the fight, flight, or freeze response.   This would explain why some people who have survived repeated threatening events will often be accused of overreacting, disappearing, or freezing (zoning out).

Some people will also complain of being sensitive to sounds, temperature, bright light or touch. During a threatening response and especially if a person is trapped in the event, the thalamus lights up causing sensory overload,( Van Der Kolk, 2014).  In this case, the thalamus continues to ” light up,” causing the brain to be in a perpetual state of sensory overload. Is it any wonder then, that folks with PTSD will use substances to achieve a break from this heightened state?

If you are reading this and relating, I probably don’t need to tell you that this unprocessed trauma causes problems with relationships, family,  and employment. If the past is in the present, or if we are continually triggered without understanding why we may begin to think “we are going crazy.”

Actually, your brain is doing its very best job to keep you safe. Your brain and your nervous system simply need guidance to process the threatening event(s) so that these triggers no longer have power over you.

This can be achieved through EMDR, Cognitive Processing Therapy or Somatic Experiencing Therapy.

Crystal Arber CC 2014


Bessel Van Der Kolk; The Body Keeps The Score, 2014

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