Flashbacks are a common symptom of Post-traumatic Stress Disorder – better known as PTSD – and other trauma-based conditions.

They are very difficult to go through, and often involve reexperiencing past traumatic events. Unfortunately, they can cause significant suffering for those that live with the condition.

But what actually happens to the brain during a flashback? We take a look in this article.

The mind is very complex

The impact on different brain regions

The brain is something that is incredibly multifaceted. The capabilities of the brain will never truly be understood – it is difficult to comprehend how advanced the mind is.

A small part of the mind is based around memory. Memory mainly affects two regions – the hippocampus and the amygdala.

The amygdala is best associated with emotional memory, with traumatic memories especially relevant here. Over the long human history, the amygdala has evolved to help humans know about danger, and is part of the human nature of survival. The amygdala stores these memories – ones including trauma and danger, meaning that when faced with a similar situation, that the brain can respond to tell the individual that they are in danger.

Meanwhile, the hippocampus is another area in the brain which is key in memory. The hippocampus is believed to go into further detail regarding memories. The hippocampus notes details about the experience – such as location, those present and what happened.

The combination of these two regions in the brain leads to memories being stored. In day-to-day life, whenever you remember an event from the past, this involves your amygdala and hippocampus working seamlessly together to provide the details.

Disruption through a traumatic event

The seamless partnership between the amygdala and hippocampus is excellent when it comes to remembering happy memories, passwords, and what groceries you need to buy.

Yet when a traumatic event takes place, the usual process involving the amygdala and the hippocampus is disrupted. The well-known ‘fight or flight’ mechanism activates in the mind when an individual is faced with a traumatic event.

During the traumatic event, a person will feel in danger, and as such the amygdala has too much to do, while the hippocampus can’t cope with the plethora of signals sent from the amygdala.

This boils down to the human nature of trying to survive. The mind prioritizes the here and now – as in the traumatic event, meaning the creation of a long-term memory isn’t considered important, but short-term survival is. This whole process does however cause the memory of an individual to become muddled.

After the traumatic event has finished, and danger is no longer present, the individual is left with only a slight memory of the event.

They have a negative emotional memory, but can’t remember the details involved. So instead of having a clear idea of what happened, the person resorts to associating certain sights and sounds from the event with danger.

The Brain in the flashback

This of course causes long-term problems – as when coming into contact with similar sights and sounds, the amygdala activates, and tries to retrieve the memory.

This signals to your body that you are in danger, and leads to the fight-or-flight mechanism again being in action.

Because the hippocampus cannot provide the details of the event, the amygdala believes danger is imminent, leading to the flashback taking place.

The brain is overwhelmed, leading to a person reexperiencing their trauma. Unfortunately, the brain is unable to handle the trauma.


So while this is quite a lot to take in, there is a clear set of events that happen which help to explain the effect a flashback has on the brain.

Explaining how a flashback too can happen makes sense after the above. The good news is, that treatment is available. In most cases, a full recovery is possible.

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