She shuffled past me, whistling under her breath,  an anxious look on her face.  She had just completed the third circuit of her apartment. 


‘What’s the matter, mum’, I said kindly, overcompensating for my mounting irritation.


‘I don’t know.  I just can’t find it?’


‘But what are you looking for?’


‘I don’t know.’  


Doris is 92.  She has Alzheimer’s Disease. And she has literally ‘lost it’.  She has lost her memory and with that lost the sense of who she is.  From being an active, engaging, if somewhat nervous elderly person, she is now little more than a husk of her former self.  It is as if she has been hollowed out.  There is no substance in her identity. 


For Wallace, her husband, it was different.  He lost his memory as a result of a severe head injury, sustained during a crash in his fighter plane in 1941.  He had no recollection of his past, but he was young enough to reinvent himself.  But he was a different person.  As his sister commented, ‘He went to war a laughing boy and came back a troubled middle aged man.’         


If we lose our memory, then we lose grip on who we are. 


Michael Conway, Professor of Psychology at Leeds University, who appeared in the last programme in the recent Horizon series, How does your memory work?, regards memory as the content of the self.  ‘It defines who we are’, he said, ‘and allows us to travel in time.  Our past informs our decisions and determines what we become.  Brain scans have revealed how reminiscing about the past and planning for the future lights up the same parts of the brain. Memory stimulates our imagination. 


Memory, Conway explained, is processed in a small comma-shaped area, called the hippocampus (latin for sea horse), deep in the temporal lobes of the brain.  Peter Forbes, who featured in the programme, was born prematurely and has an underdeveloped hippocampus.  Forbes has no past and no future; he just lives in the present, but he is not distressed.  It takes imagination; the fear of what might happen, to worry.  Peter has nothing to worry about because he has no imagination.   


Most of what happens to us is forgotten.  We only remember the events that have emotional significance (or we impart emotional significance to – we have to make facts meaningful to recall them for exams).  Just reflect on what has happened to you over the last three months.  You will have forgotten most things, but the events, situations you do remember will have been those associated with strong emotion, anger, sadness maybe, passion, and those you will remember very clearly.   Married couples will remember certain romantic episodes in their courtship with great clarity.  The bereaved remember every detail of their partner’s death; the shock etches the images on the brain. 


But, bearing in mind the eventful lives most of us lead, there is an enormous amount of emotionally charged memories to be dealt with.  One of the great mysteries is how this information is processed, categorised, stored and retrieved.  Can it just be as associations, patterns stored in connections between brain cells, electrical messages or chemical codes?  


Upon reflection, it seems that the things that happen to us on a daily basis are filtered through our life experience.  We ascribe meaning, significance to them according to the themes of our lives and they are catalogued according to what they represent for us.  Thus they come to consolidate our life script and inform how we think about what happens.  This process determines our personality and explains why people tend to perceive what happens to them idiosyncratically and react predictably. 


But if that was all, we would never change.  Sometimes, something happens that is so outside our experience that it requires a major shift in attitude to accommodate out.  Also we are social animals;  we influence each other.  Just as sex allows the blending and mixing of characteristics to create a new individual, so attachment creates new ways of thinking.     


For events to be catalogues and stored, they have to be reworked.  Dreams seem to play a particularly important role in this process.  From what we recall on waking from dreams, it appears that they relate the important events of the day to our dreads, fears, but also joys of our lives,  creating allegories that may offer a magical resolution.  We dream as we think – using association, displacement and condensation, but dreams are irrational; they defy logic. The surrealism of dream might facilitate a more seamless conversion of event into meaning.  So we don’t have to remember millions of disconnected events.  Our personalities are constructed from no more than a score of interconnected themes.  Our memories illustrate and reinforce those themes.    


Thoughout our life, our bones are remodelled throughout our lives to respond to physical stresses imposed on our body.  Our memories are similarly remodelled but in response to stress of life experience.  We rework the themes and most meaningful events of our lives many times and every time we rework them through thought and dream, we change them into a form that is more acceptable to our view of ourselves and more relevant to our current experience.  Memory is malleable.  Recalling it allows adjustments to be made.  The narrative changes by increments of self deception into a mythology.  People remember the same traumatic event in very different ways  because their memories are passed through the filter of their own personal history.           


Not all events can be processed in this way.  If we have the misfortune of living through an event so disturbing and traumatic that it defies remodelling,  then the memory remains active, unchanged, playing again and again like a tape through the mind as fresh as if it happened yesterday, preoccupying our daily thoughts and interrupting our sleep. This is a feature of what is known as Post Traumatic Stress Disorder (PTSD).  People with PTSD don’t dream; the tension of what has happened interrupts their sleep and defies modification by dream and thought.  It can only be replayed as a too-painful narrative, inviting edition yet confounding it.  A waking nightmare, their preoccupation robs them of past, future, meaning and life.  


Freud recognised how many of his patients suffered from unprocessed reminiscences.  Their trauma had not been worn away by time, but in some cases the memory was repressed and played out in a physical symptom seemingly disconnected from but still representing whatever caused it. 


In Michel Gondry’s cult film, Eternal Sunshine of the Spotless Mind,  Joel and Clementine, underwent some kind of brain stimulation treatment to erase memories of their unhappy love affair.  In real life, as shown in How does your memory work?,  Genevieve Smith Courtois takes propranolol, a common drug, that is been in our pharmacopeia for 40 years, to dampen the memory of a sexual assault she suffered nine years previously. While recollecting the assault under laboratory conditions under the influence of propranolol,  her symptoms diminished to below the post traumatic threshold.  This illustrates the capacity of recall to remodel memory.  Propranolol is often prescribed for panic attacks.  By diminishing emotional tension, it reduces the intensity of the recall to a point where it can be allowed to wear away.  The group of tranquillisers known as benzodiazepines are commonly used to block the memory of  disturbing and painful surgical procedures.       


But although amnesic drugs may help us deal with trauma,  they are not necessarily such a good thing.  We all learn from experience and gain a deeper sense of ourselves.  Our identities are based on our memories.  Suppressing those memories we find painful might just convert people to cheerful automatons, Stepford wives.  With no pain and passion, there would no great literature, no great art or poetry.  Life would become meaningless.  All that might be left is a disturbing sense that we had lost it without ever knowing what it is.