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DCoE Director Explains Science Behind PTSD

Brain cross-section
Courtesy graphic by Heather Miller Seger

If you were to ask random strangers, “What is the most important organ in the human body,” what answers do you think you might get? Many people would say the heart and lungs, but for most it would probably be the brain. The brain’s role is central in our lives but that’s often overlooked or taken for granted until the brain is impacted by illness or injury.

Like any other organ or organ system in the body, it’s important to understand what the underlying problem is in order to effectively treat it. This is particularly true when we think about an individual with posttraumatic stress disorder (PTSD).

You need to know the science.

There are three brain structures that play key roles in the science behind PTSD. They are the amygdala, hippocampus and prefrontal cortex.

The amygdala is the stress evaluator. It continuously monitors all situations for danger and decides when to react. The sights, sounds and smells of frightening and dangerous memories are stored here. When the brain recognizes similar situations, the amygdala sends out danger signals and gets the body ready for a flight or fight response.

The hippocampus stores and retrieves memories, everything from where you attended second grade to where you parked your car three hours ago. If your brain is a computer, the hippocampus is the hard drive.

The prefrontal cortex is the large part of the brain sitting right behind your forehead. This is the executive-functioning area responsible for rational thought and decision making. In the computer analogy this is the central processing unit running the programs.

In the moment of a traumatic experience the hippocampus frantically tries to cope and calm the amygdala alarm circuit. In some cases the hippocampus is not able to calm the amygdala, resulting in damage to the hippocampus region of the brain, which lessens the ability of the amygdala to produce calming thoughts.

With PTSD, the nerve circuits connecting the amygdala, hippocampus and prefrontal cortex aren’t working correctly. The hippocampus can’t store the memory and the prefrontal cortex can’t override the hippocampus to tell the amygdala to calm down when there is no danger.

PTSD is a cluster of symptoms that occur for at least a month or more. When someone has PTSD they persistently re-experience the traumatic event, through recurring thoughts, nightmares and flashbacks because the hippocampus is not storing memories correctly. They will also experience persistent avoidance of stimuli associated with the trauma such as connected thoughts, feelings or places because the amygdala is essentially yelling, “danger!” Additionally, a patient with PTSD will have persistent increased arousal that may cause hypervigilance, irritability, difficulty sleeping or an exaggerated tendency to be easily startled.

As difficult as PTSD can be, the good news is that when service members and veterans seek help they can get better. The brain, like other organs, can heal. It’s a matter of working with the amygdala, hippocampus and prefrontal cortex to make the traumatic memories safe.

Increased awareness of the science behind PTSD can help reduce the barriers to care and increase the number of service members, veterans and their families who are willing to get the help they need to recover.

This blog post originally appeared on the Military Health System website.

Comments (9)

  • Gerald Griffin,MD 11 May

    Good effort--at explaining the symptoms and the origin in the brain sites......but........the science actually lies in the chemical imbalance that causes these brain areas to misfire and express itself as 'ptsd'......keep on keeping on....
  • DCoE Blog Editor 13 May

    @Gerald, Thanks for your comment.

  • Fred 13 May

    Good try but this is only half of the story. According to DSM-IV - the bible of the psychiatrists - when you have ptsd symptoms for 3 months you have chronic ptsd. This ptsd will not cure anymore. When you say people with ptsd get "better" you are using very vague labels that can be very misleading. For diagnosis of ptsd see and for Treatment of Posttraumatic Stress Disorder: An Assessment of the Evidence


    After reading these reports on-line you can make up your own mind about diagnosis and treatment of PTSD. For your info. I have chronic PTSD from a military mission and will never heal. You cannot give a military men/women an exposure treatment because then you must put them back in a realistic or real war situation. Without wounded people and/or dead bodies this will only be a game.

  • Dan Courtney 13 May

    The amygdala won't shut up because it has not gotten the signal from parts below that the severe threat has been vanquished. The intense defensive energy keeps being generated by the reptilian brain and the mind remains in a state of focused threat resolution mediated by the vagal nerve - the brain is engaged in the pursuit of conquering the threat which hasn't happened yet - the circuitry is working correctly, there is no misfiring - the necessary experience of triumph hasn't been achieved and that mission takes precedence over every other in the present. The mind is trapped in the ubiquitous approach-avoidance conflict with its own implicit (reptilian) memory.
  • Ken Harwood 14 May

    A not-so-logically-tight concretization. Of course we all know that love and honor are just collections of brain function!
  • dave plunkett 14 May

    Sir, many more veterans would seek help for PTSD if the VA was welcoming or at least user friendly. The mass of paperwork for claims, and complexity of same discourages most veterans; they often quit on the VA, or seek help elsewhere. After my 2 combat tours in Iraq, seeking help for PTSD was a challenge as difficult, if not more so than IRAQ. THANKS
  • DCoE Blog Editor 15 May

    @Dave, The following response was provided by a contact with VA.

    Have you tried a Vet Center? (  A Vet Center is a safe and protected place to talk and a place where you will find confidentiality – and no stigma. VA’s 300 Vet Centers offer flexible hours in an easily accessible community-based setting. Vet Center staff are knowledgeable about the resources available for you and most are fellow combat Veterans themselves – so it is Veterans serving Veterans. All family members are welcome and there is no cost….ever. 


    Vet Centers offer individual or group counseling, Military Sexual Trauma counseling, marital/family counseling and bereavement counseling. They can provide drug and alcohol referral, liaison with VA and community resources, benefits assistance referral, and community education and career referral. They also operate a 24/7 Call Center: 1-877-WAR-VETS (927-8387)

  • Tom Santrizos 08 Jun

    The Navy Capt. was expressing the science in layman's terms, so that even veterans who follow these sites can understand this devastaing affliction, which manifests itself in many ways and cannot be put into a concise little box.  Dr. Griffin's statement is most assuredly understood by an average education veteran.  He does not need to show off his mastery of the obvious.  Fred hit center target.  One of the best statements I have read.  However, depends on the severity of the trauma as to the last part. Very informative by Dan Courtney.  Really made sense to me. Dave Plunkett, whom I assume is a veteran or a counselor, presents a very real scenario, one that sadly has led to the deaths of many a serviceman or veteran by their own hands.  To the contact at the VA idea, it works for many, however not all first encounters with the VA system, especially the first time, with the veteran or serviceman walking in the door full of guilt and expecting the "STIGMA" possibility turn out always positive.  My experience sure wasn't.  I got grilled by a counselor for an hour about my "STRESSOR".  It was complicated.  After my 3rd visit I never went back and slammed the door on the way out.  Sometimes anger can get the better of you.  My whole perception and vision of the VA system is negatively skewed.  

    However, I am hanging in there and finally have teamed with a PhD who can put himself on my level, whether it be everyday ordinary life or intellectual pursuit of discussion of the signs of, stressor avoidances, brain function, physical reactions thereof, or just talk about the weather.  When we started, the second step of reliving my personal trauma, which was one-on-one life or death personal up close and in your face gut reaction, I could not do it and almost lost any desire to ever go back for treatment again.  For what it is worth, I am a Thailand veteran who went into Laos to lay sensors on the "Trail".   
  • DCoE Blog Editor 10 Jun

    @Tom, Thank you for sharing your thoughts and experiences.

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