Your humble reporter has had more than his fair share of major life events. As a sixteen year old I was a passenger in car that had a meeting with another vehicle driving down the wrong side of the road. This was in England, where folk always do drive on the “wrong” side, but the fellow who was kind enough to arrange the collision could never explain why he was driving on the “American” side.
The interesting thing is that the memory of the crash is seared into my memory: I can remember the license plate of the vehicle that hit us. Some people call that a “flashbulb memory.”
If you live in the United States you probably have clear and fairly accurate memories of where you were and what you were doing on September 11th 2001.
This kind of experience is not uncommon: most of us have noticed that events that occur during heightened states of emotional arousal, such as fear, anger, happiness and sex are far more memorable than less dramatic occurrences. The emotional “load” of an event is a key factor in remembering it. Previous studies have confirmed that heightened states of emotion can facilitate learning and memory.
This makes good evolutionary sense: emotionally charged events are likely to be the ones that we need to remember. From an evolutionary perspective, it is more important to remember where Mr. Saber-tooth Tiger lives, rather than the names of the Kings and Queens of England.
Therefore the regions of the brain that are responsible for the storage of memories need to distinguish between important experiences and those that less significant for survival. The brain must have some mechanisms for giving priority to emotionally charged memories, so that they are converted and stored in long-term memory.
The downside is that in some situations, for instance posttraumatic stress disorder (PTSD), this process can become pathological and people can be tormented by persistent vivid memories of traumatic events.
Writing in the journal Cell, researchers from Johns Hopkins University and their collaborators at Cold Spring Harbor Laboratory and New York University may have identified the biological basis for this phenomenon. Memories in the brain are held in neurological circuits and each new experience creates a new circuit. The investigators have found that the hormone norepinephrine, which is released during emotional arousal, serves to "prime" nerve cells to remember events. They do this by increasing the neurons’ chemical sensitivity at the precise sites where nerves rewire to form new memory circuits.
Norepinephrine is often described as one of the "fight or flight" hormones and it is likely also involved in the third type of response to a threat, which is “freeze.” In the brain norepinephrine energizes the circuit-building process by adding phosphate molecules to a nerve cell receptor called GluR1. The phosphates help guide the receptors to insert themselves next to a synapse.
So when the emotionally-charged brain needs to form a memory, the nerves have plenty of available receptors to quickly adjust the strength of the connection and lock that memory into place.
The researchers targeted the GluR1 receptor after discovering that if it is disrupted in mice, the little creatures develop spatial memory defects. They tested the idea by either injecting healthy mice with adrenaline or exposing them to fox urine, both of which increase norepinephrine levels in the brain.
They then analyzed the brains of the mice and found increased phosphates on the GluR1 receptors and an increased ability of these receptors to be recruited to synapses.
When the researchers put mice in a cage, gave a mild shock, took them out of that cage and put them back in it the next day, mice who had received adrenaline or fox urine were likely to "freeze" in fear, compared with mice who had not been exposed to the adrenaline or fox pee. This implies an enhancement of their memory of the cage and its unpleasant associations.
In a similar experiment with mice genetically engineered to have a defective GluR1 receptor, adrenaline injections had no effect on mouse memory. So this provides us with further evidence of the "priming" effect of norepinephrine on the receptor.
There has been a lot of recent interest in using medications like beta-adrenoreceptor blocker propranolol – which prevents some of the actions of norepinephrine - to prevent the development of PTSD in people who have been exposed to extreme trauma, and this research may provide the scientific basis for this kind of therapy.
On the other hand, this research leads me to predict that people with overactive GluR1 receptors may be constantly curious about their environment, but also likely to be chronically anxious and more likely to develop PTSD.
We have known for years that propranolol and other beta-blockers may attenuate some of the physical symptoms associated with anxiety. Most people had assumed that the medicine worked by reducing heart rate, shaking and sweating. But experienced clinicians usually find that beta blockers that cross the blood/brain barrier work best, and it may well be that these drugs also have direct actions in the brain itself.
“Recollection is the only paradise from which we cannot be turned out.”
--John Paul (a.k.a. Johann Paul Friedrich Richter, German Novelist and Humorist, 1763-1825)
“The existence of forgetting has never been proved: We only know that some things don't come to mind when we want them.”
--Friedrich Wilhelm Nietzsche (German Philosopher, 1844-1900)
“The moment we find the reason behind an emotion … the wall is breached, and the positive memories it has kept from us return too. That's why it pays to ask those painful questions. The answers can set you free.”
--Gloria Steinem (American Feminist, Political Activist and Editor, 1934-)
Dear Dr. Petty,
I'm very excited to have found your blog. I want to thank you for the work that you are doing in the field of Holistic Health.
Dr. Petty, I am a coach and Master Practitioner of Neuro Linguistic Programming and I specialize in working with women who are emotional eaters. Considering your expansive knowledge in the field of medicine, It should probably come as no surprise to you that a large majority of women who are emotional eaters also have histories of being abused.
Presently I am in the midst of writing a non diet self help book for the woman who has learned to hate her body and unconsciously prevent her own success at weight loss. The book is entitled, Say Goodbye to Dieting: The Juicy Woman's Guide to Reclaim Your Power over Food, Love Your Body and Yummy up Your Life.
Dr. Petty, I am passionately devoted to helping women overcome emotional eating and want very much to ask for your help to put some threads together for me. Would you agree to sharing some of your thoughts with me and giving me permission to quote your research in my book?
If you are amenable to answering a few questions, I would like to share some of my insights with you for your comments.
From your blogpost, I understand that Norepinephrine stimulates neural connections creating heightened memories connected with pivotal events in our lives, thus creating the opportunity to recall the flashbulb memories that you discuss.
In the case of abuse, this memory and/or similar memories replay each time they are triggered by a given stimulus, such as in the case of a person with PTSD. It is my understanding and my personal experience that as a result of that stress trigger, it is common for a woman who has connected food to feeling safe to have a kneejerk response to stress embedded in her subconscious mind directing her to continually seek out food in the presence of stress. Dr. Petty, have you done any studies or can you direct me to a study which would enable me to explore this further?
As a personal note, in my capacity as a coach and a woman with my own history of abuse, after years of pursuing traditional therapeutic methods to encourage healing, I have finally found great relief from this internal tormenting of vivid memories in the form of a simple self adminstered tapping process called Emotional Freedom Technique, or EFT.
EFT is based on the science of Acupuncture, and it entails tapping on specific key acupressure points while at the same time thinking about the problem, pain or negative memory. This creates an internal release response in the body triggering natural stress relief chemicals that promote tension release and muscle relaxation. It also works to change the way that a person remembers events, neutralizing emotionally charged memories in minutes.
I have found that this works like magic to relieve pain of all sorts where there is an emotional component holding negative memories in place.
Dr. Petty, can you please explain how this tapping creates a physiological change in the body? In your expert opinion, what has to occur in order to discharge or rewire these negative memories?
In relation to the question of emotional eating, I understand that there is an actual mind/body connection that is at work in the individual struggling with obsessive eating.
According to Dr. Judith Rodin's research at Yale University, she showed fasting volunteers beefsteaks which were then cooked in front of them. Their blood was drawn and analyzed before and after the testing. In the during and after phases, the subjects' insulin levels showed a dramatic increase. Taking into account, that one of the things that insulin does in the body is it converts nutrients to fat, Dr. Rodin theorized that people can gain weight by simply seeing, hearing or smelling food cook.
It is my understanding that the chemical responsible for this elevation in blood sugar is Acetylcholine and it is produced in response to signals that come from our brain signalling the anticipation of food.
I understand from reading your blog that you have done some research with athletes and other people using visualization to achieve a specific outcome.
Dr. Petty, I'm sure that you are familiar with the work of the late Dr. Maxwell Maltz, creator of Psycho Cybernetics in which he draws the parallel of a person's internal image of themselves manifesting in physical reality.
In the case of a woman struggling with a negative internal image of being 'fat' or ugly due to the fallout from abuse, would you anticipate that her preoccupation and fretting over her weight, feeling badly and tendency to reinforce the negative image of an overweight body, would cause her to remain heavy?
Would the quality of her thoughts become commands to the subconscious mind to remain over-
weight?
Are you familiar with any recent studies that address this negative internal self image
issue? In your esteemed opinion, what would you advise women who want to override this tendency to dwell on the negative?
Is consistent visualization sufficient to change this or is there another element that you feel needs to be implemented?
Dr. Petty, I realize that these are many questions to address. Would you be willing to allow me to interview you for the responses?
Let me know what you think. I look forward to touching base with you soon.
Sincerely,
Andrea
Posted by: Andrea Amador | October 15, 2007 at 12:08 PM
I wonder what the impact of this research will be on research into "repression" or memory loss.
Posted by: Caitlin | October 22, 2007 at 09:45 PM