Are our memories really like a filing cabinet?

Are our memories really like a filing cabinet?

In 2001 Jacquie E. Pickrell and Dr. Elizabeth F. Loftus carried out a simple experiment at the University of Washington.  After seeing an advertisement showing Bugs Bunny at Disneyworld a third of the people involved remembered not only seeing him when they had visited there, but clearly recalled shaking his hand.  The fly in the ointment of course is that Bugs Bunny, as a Warner Bros character, has never appeared at Disneyland.

The fact is that whilst we might think of our memory as a filing cabinet, containing our original memories, it is in fact much more malleable and plastic than that.  According to some researchers it may even be the fact that the act of remembering permanently alters memories.

The generally accepted view of memory is that it is created by neurons in the brain developing new connections, and building them into the brain’s synapses.  The assumption has been that once a memory has been constructed it is “consolidated” – effectively made permanent and incapable of being easily undone.

However research into memory in rats suggests that the steady state theory of memory might not be correct.  Experiment dating back to the 1960’s have shown that drugs that prevent the creation of new proteins can weaken memories when their recall was prompted.  The implication of this for the “steady state” theory is that it suggests that recalling a memory may involve the same process of building information into the brain’s synapses.  This process, dubbed “reconsolidation” by researchers, would mean that memories are open to being re-written every time they are accessed.

Under this model then the more we revisit our memories, and the more we discuss them with other people, then the more susceptible they are to distortion.  For those people who set great store in their memories, and use them to bolster their sense of a continuous self, this may be an unsettling possibility.  However it does suggest a way in which people troubled by intrusive or unwanted memories might be able to gain some relief.

Post Traumatic Stress Disorder (PTSD) affects about a third of people who go through stressful, frightening, or distressing events, from combat situations to road traffic accidents.  Whilst the symptoms of PTSD vary between people, they commonly include reliving the traumatic event through vivid flashbacks, intrusive and unwanted thoughts, and nightmares.  Based on the theory of reconsolidating memories, and the effect of drugs that block the creation of proteins, Alain Brunet, a Montreal psychologist, has conducted promising clinical trials involving people with PTSD.

In his first study, Brunet’s patients took the drug propranolol.  Routinely used to treat high blood pressure, and sometimes used to address stage fright, propranolol blocks the neurotransmitter norepinephrine involved in protein creation. This is the reason behind its known side effect of memory loss, and it was this capacity that Brunet was looking to exploit.

Following promising results Brunet conducted a second study with with nearly 70 PTSD patients, some of whom took propranolol and some a placebo.  Both went through the same protocol of reading out a script about their traumatic event, based on interviews carried out with them earlier, once a week for six weeks.  The people who took propranolol each week before reading their script showed a 50 percent reduction in nightmares and flashbacks in their daily lives, a reduction maintained long after the physical effects of the propranolol had finished.

Brunet described the results as “week after week the emotional tone of the memory seems weaker”, with those on propranolol starting to “care less about that memory”.  The treatment wasn’t designed to eradicate the memory, or to make it inaccessible, but instead to change the quality of the memory and the response that it prompted.

The plastic nature of our memory then may actually be a positive, in how it can help those struggling with traumatic memories, but in how it allows all of us to remember people and events in ways that are congruent with the way we see ourselves and the world now.

We’ve discussed memory formation in the brain but what about memory formation in your heart?  Read more about why some people believe in this not as a metaphor, but in cell memory as a reality.

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