Trauma and Memory: Brain and Body in Search for the Living Past

There’s a complex relationship between Trauma and Memory: Brain and Body in Search for the Living Past.  This is in no small part because traumatic memory isn’t in the past – it’s a part of the current reality of those who have been traumatized.  It’s also in part because traumatic memories are different than our regular, explicit memories.  Trauma and Memory is by Peter Levine – the same one who wrote In an Unspoken Voice.  In fact, he mentions he’ll be focusing on this work immediately after that one.

I won’t go into what trauma is here; you can see Peter’s other work or Transformed by Trauma for a basic understanding of trauma.

Traumatic Memory is Memorex

In my review of Mistakes Were Made (But Not by Me), I included a heading that explained that memory isn’t Memorex – that is, identical to the original event.  That’s true of our explicit memories – those that have been processed.  However, unprocessed memories, those of a traumatic nature, are in fact immutable, exact copies of the experience of the moment.  They’ve not been processed through Broca’s area of the brain to be made explicit and are therefore somehow immune to the natural shift that happens as we recall memories.

Memory Formation

The actual formation of long-term memory is a complicated process.  It can be disrupted in several ways.  First, most memory consolidation and conversion happen during sleep.  If we interrupt sleep at the wrong moment, we can effectively prevent learning.  (See How We Learn for more.)  We can also disrupt learning by creating an event that is too emotionally charged.  This creates a situation where critical portions of the brain are not active when they should be, presumably due to overactivity in other areas.  Broca’s area is commonly thought of as the linguistic processing portion of the brain, but that’s not the complete story.  Broca’s area is responsible for syntax – in other words, ordering and orienting – and appears to play a key role in conversion of physical sensations into meaningful explicit memories.

To understand the mechanics that cause areas of the brain to reduce activity, it’s important to recognize that there’s a maximal rate of glucose (power) transfer across the blood-brain barrier.  When we engage our brains most fully, we necessarily create a power deficit, and the brain responds by taking components offline.  (See The Rise of Superman for more.)

As I mentioned briefly in my review of The Body Keeps the Score, traumatic memories overload the emotional centers of the brain, and this causes the breakdown of the conversion process.  The problem is that the brain will continue to attempt to reprocess these memories repeatedly until it finds an acceptable way of integrating them.

To Predict

Inside Jokes proposes that the primary function of consciousness is prediction.  To perform its function, it processes input and uses it to create models that are then used to predict future events.  Gary Klein in Sources of Power shares his experience with fire captains who couldn’t articulate the way they were making decisions.  The theories at the time were along the lines of Decision Making, where decisions are made slowly, thoughtfully, and sequentially.  What he observed was that fire captains weren’t doing this – and they couldn’t articulate how they were making their decisions.  (See also Seeing What Others Don’t for Klein’s work in this area.)  The discovery was that they were building models of how the fires work, including all the variables necessary to predict the source of the fire and the factors feeding its growth – or inhibiting its growth.  They built this model by integrating their experiences from hundreds of other fires.

Because these models are so important to navigating the world, our brains will continue to try to make sense of – process – experiences until they complete their work of integration.  This means that unprocessed traumatic memories will intrude into daily life.

Memory Types

Before continuing, it’s important to note that there are different kinds of memories.  They are:

• Explicit
  • Declarative
  • Episodic/Autobiographical
• Implicit
  • Emotional
  • Procedural
    • Learned Motor Actions
    • Emergency Response
    • Response Tendencies: Approach/Avoidance

The knowledge management discipline sees these slightly differently but does acknowledge the array of memory types.  (See Lost Knowledge for more.)

Timeless

We use our explicit episodic memories to help us orient in time and space.  We use them to help us understand where we are and where we’ve been.  However, this requires the conversion into explicit memory, which is missing for traumatic memories.  As a result, traumatic memories are quite literally experienced as if they’re happening in the present moment.  Our brains cannot tell the difference between a traumatic memory and currently occurring facts.  It’s no wonder that people with traumatic memories feel overwhelmed and unsafe – because, to their brains, they are.

Erasing Memories

It’s the subject of science fiction, but too few people realize that it is a scientific fact.  The study was testing what would happen if a key protein needed for memory retrieval was blocked at the time of memory recall.  Mice were trained with classic conditioning to fear a sound.  The protein inhibitor was injected, and the sound was played.  They, predictably, didn’t experience fear.  The memory was blocked.

However, the spooky result was that they no longer feared the sound even after the protein inhibitor had worn off.  Somehow, accessing the memory at a time when the protein to allow for retrieval wasn’t available had caused them to unlearn the behavior – permanently.

Reenactment

It’s not clear the total implications of this; some researchers and clinicians have observed children exposed to trauma in their preverbal time to repeat or reenact the traumas they experienced even without conscious knowledge of the trauma.  Even mice taught to run a maze seem to pass along that memory of the maze – at some level – to offspring, as was demonstrated with a creative experiment where mice were taught a maze in Australia and then offspring were presented with the same maze (pattern) in New York.  The offspring were statistically faster than they should have been at solving the maze.  The same thing happened when the pattern was reversed – it wasn’t just the city that made them faster.

This was further validated experimentally by using a cherry scent to precede a shock.  Great-great grandchildren of the original mice in the experiment had a stress reaction to the scent – even though they had not themselves been exposed to the scent or the training.

For all the things that we know about Trauma and Memory, we don’t know enough yet.