4 MIN READ | Psychotherapy

Terence Watts

The Lizard Brain and PTSD – Why We Just Can’t Stop the Flashbacks

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Terence Watts, (2021, August 28). The Lizard Brain and PTSD – Why We Just Can’t Stop the Flashbacks. Psychreg on Psychotherapy. https://www.psychreg.org/lizard-brain-ptsd/
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We hear an awful lot about PTSD (posttraumatic stress disorder) nowadays, and it’s certainly a distressing condition that wrecks lives and relationships and not infrequently ends in suicide. It’s difficult enough to understand the myriad destructive symptoms and flashbacks that are so frequently part of the condition. But the fact that it almost certainly originates in a part of the brain that is part of our inherited survival kit, the ‘lizard brain‘, can seem even more puzzling.

The lizard brain refers to an entire brain region which is evolutionarily the oldest part of the organ. It includes the brain stem, amygdala, and cerebellum; and was the only brain our most ancient ancestors had – and we’re not talking here about ancient humans, but ancient life, the earliest sentient creatures of some 600 million years ago, long before mankind walked the earth. Long before any mammals, in fact. Because it was the only brain those relatively simple life forms had, it was responsible for maintaining every essential bodily function, including feeding, breeding, and responding to threat – the major elements of survival for both the individual and the species.

Evolution doesn’t replace successful organs but improves upon them, so in our modern brain, many millions of generations and evolutionary branches later, that part of the modern brain is still the ‘first responder’ to anything that triggers instinctive behaviours. Those behaviours may be innate or acquired, but they are always beneath the level of conscious control and a good example is that when you accidentally knock something from a shelf, for instance, you instinctively try to catch it without pausing for thought. It’s exactly the same with our responses to threat, anger, and other stimuli – we can control what we do with them but are powerless to prevent them from arising in the first place.

There are three specific aspects of this part of the brain, particularly the cerebellum, that are of vital importance as far as PTSD is concerned. The first is that it stores patterns of stimuli and responses to be referenced for future events; the second is that any response must always be discharged in motor action or anxiety results; and the third is that there is no awareness of the passage of time – if something was, it still is.

The fact that we can only be consciously aware of one thing at a time is key. Imagine a scenario where a mugger yells abuse at us, demands we hand over our money, and threatens to stick a knife in us if we don’t comply. Our instinct might be either to remonstrate or try to do what they say in order to survive but whatever that response is, the threat is not negated immediately. It still exists. The lizard brain creates more survival responses that we just don’t consciously observe or discharge… so they remain as a ‘pseudo instinct’ that can be triggered by anything that echoes even just a part of the original trauma. So, later, when we hear somebody shouting, even a friend, that pseudo instinct becomes active, maybe violently so, creating with it a vivid recall of the relevant part of the event – the yelling of abuse, in this case; and we call that process a PTSD flashback. 

Only a part

In the flashback, we experience a subconscious reminder of only a part of the trauma, not the whole thing. The pattern is incomplete, meaning the response cannot be discharged in its entirety. So as far as the lizard brain is concerned, the threat to survival still exists, and we are still at risk. It’s a simple but totally effective survival tactic. An instinctive response is only created if it’s needed; and if it’s needed and not acted upon, then as far as the lizard brain is concerned, danger increases. The result is that whenever the tiniest thing parallels some part of the original event, the lizard brain recognises it and a full trauma response will be retriggered. It often includes one of the most common of PTSD responses, anger, which is directly associated with survival. Anger is a 600 million-year-old fundamental aggression response to fear, and it’s driven by that lizard brain recognising danger. It’s an oddity that during the trauma itself, anger might not be acted upon or even noticed if the focus was on ‘flight’ rather than ‘fight’

This can lead to apparently irrational and over the top outbursts:

  • Somebody screams abuse at another over a minor transgression.
  • An individual collapses in tears when somebody raises their voice a little.
  • A driver is triggered into a violent road-rage attack when somebody overtakes them on the wrong side. 

The reason for such reactions is that the energy associated with whatever is happening now is added to the energy of the undischarged instinct that has been waiting in the lizard brain for the opportunity to ensure our safety. That the current event is minor by comparison is of no consequence, since the lizard brain has no capacity for logical or rational thought. If the current trigger creates one gram of energy and the original event created one kilo of it, then one kilo and one gram is going to be vented; or to put it more succinctly, it’s rather like somebody trying kill his next-door neighbour because their TV was too loud.

PTSD is not only completely disabling in many cases but is also notoriously difficult to resolve in the short term. Fortunately, many modern neuroscience-based therapies can often provide a faster and more complete release than ever before. Some seek to closely mimic the normal processes of psychological assimilation and processing of ideas, seeking to overwrite the original stimulus. That way, it no longer exists in our lizard brain as a need for motor action and is referenced only as a memory – and that’s exactly the process that occurs when an instinct is discharged in motor action at the moment of generation.

PTSD has long been considered an inevitable result of trauma, and perhaps it is. But as with so many mental health issues, neuroscience may have the ultimate answer. 


Terence Watts is the creator of Brain Working Recursive Therapy (BWRT).

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