How memory works is one of the more unusual discoveries of modern neuroscience. Once a memory enters consciousness it typically includes a sense of veracity, a sense that the content of the memory accurately reflects the circumstances being recalled. When we compare our memories with others who were at the same event we quickly learn how each individual lays down their own version of things, a fact reporters and lawyers work with in a practical way every day.
This universal experience of accessing memories provided brain researchers with a whole host of interesting questions starting with, what is a memory? The neuroscientist knows the brain trace of a memory must be using particular neural circuits, like any brain state. One hypothesis was that when a memory is created a particular set of neurons is assigned the job. This gave rise to what is sometimes referred to in cognitive science as the grandmother cell; the idea that your image-memory of your grandmother’s face is bound up with your grandmother neurons. In this model accessing the memory of your grandmother is as simple as allowing those grandmother neurons to fire. This hypothesis agrees with our intuitive notion that a memory needs to be somewhere since that is what it feels like to access one; like reaching out to contact something already there, laid aside in the past when the memory was created.
It turns out this hypothesis was wrong. There is no assignment of particular neurons sets to particular memories as far as we can tell with today’s theories, instruments and data. What actually happens is that the brain re-creates a pattern of neurological firings. The memory is not in the cells but in the pattern. The act of memory is not re-accessing but an act of re-creation.
Consider an event that is now a memory; say learning how grandma’s face looked while she baked cookies. When the event was occurring your brain was in a particular state. Its neuronal firings were forming a specific configuration by which it processed the sensory signals and the emotional and physiological context of those moments. Part of this enormous symphony of electrochemical information exchange gets relayed through the hippocampus which lays down the perception of grandmother’s face as a memory to keep. The details of how this happens are not understood but the process is believed to work with both short term and long term memory differentiation and we know, somewhat surprisingly perhaps, that it requires a healthy amount of REM sleep before the memory is actually retained long term.
Now when the smell of cookies immediately brings to mind grandma’s face, what research shows is that the pattern is recreated. A memory depends on a particular configuration, a re-creation of a previous brain state. In the grandmother neuron hypothesis we expect a few hundred neurons captured the information about grandmother you will later need to recall. What was found instead is that the whole brain gets into the act of calling forth grandma’s face with hundreds of millions of neurons involved. Oh, and one of the neurons involved in remembering grandma is also involved when you remember your first day of school and every time you recognize the color red or some such. The memories are not ‘in’ the neurons, they are ‘in’ the pattern.
The act of recall then is not at all what it seems to be before it is analyzed. It seems introspectively that when we perform an act of memory we are looking into the past, that we are examining a photograph or movie with our inner eye. In fact what is occurring is a re-creation of the information processing dynamics that occurred in the past. We don’t examine a photograph, we re-create the set and setting in our imaginations. This discovery certainly explains all those observations captured in our folk wisdom about how unreliable memory can be.
In getting aquatinted with our minds this is worth spending time with in contemplation. What are memories? Where and how are memories stored? How are they created? What happens when we remember something? What does it mean when our species drives another one to extinction so that the whole of that expression of life is now no more than a memory?
I am usually persuaded that the best model we have for the mind that accounts for all the wild and weird, as well as its everyday manifestations, is that consciousness is a non-local phenomenon just as such are understood in quantum mechanics. Parts of the evidence for some such strangeness at the heart of our consciousness are the puzzles surrounding this feature of memory which is so central to our experience. Consider, if a memory is a re-creation of a previous brain state, what triggers it? What form must the trigger take to be able to re-create the pattern accurately enough to provide a memory that in turn is accurate enough to be useful? Just how many of these previous brain states are accessible? Under hypnosis and other altered states an amazing spectrum of recall can become accessible. Perhaps not even the smallest detail of any experience is ever wholly forgotten.
Or consider just how many memories the human brain is capable of storing, and where exactly are they stored? They reappear as a re-creation of previous patterns, where are those memories held when they are not being recalled? The Abhidharma postulates what is called the Alaya consciousness as the repository for just his sort of thing. And what does all this mean for the ontological status of my experience of this present moment when it too is no more or less than a particular pattern of energetic neuron firings I might one day remember with no more or less sense that it was real than that which accompanies any other memory?
By the way, this type of contemplation can aid us when suffering pain in the present moment. Recalling that the present moment has no inherent ontological status greater than any other moment of consciousness you have experienced in the past can provide some distance, some separation from the pain, some space from which it can be worked with. The trick is you need to remember this in the midst of the pain. How can we better our chances of remembering such wisdom in the midst of intense mental states like pain? By what we refer to as mind training; the creation of new patterns and then strengthening those through repeated use. This brings us to another word for this process of laying down these neurological patterns in our memory: learning.
The rule of nervous system neural nets is that use strengthens the circuits being used, making it more probable that they will be us again. Since the information is in the pattern, this manipulation of probabilities is very important.
Imagine this simple model is a small part of your memory of the times tables and the path 1 – 2 – 4 represents 7 X 7 = 49. Through rote memorization you learned to take this path every time. You let atrophy the potential but unused path 1 – 3 – 4 which represented say 7 X 6 = 49. When you were reciting your times tables you we’re running through this 1 – 2 – 4 circuit again and again, teaching your brain to make this particular information readily accessible and that when it is accessed, it needs to take this particular form to be useful. This ability to strengthen the ability to ‘do it right’ through repetitions is also what is behind the ability we have to master a craft or a musical instrument. However complex the skills required for mastery might be, they can be honed through this process that strengthens some paths at the expense of all those others which might be taken by someone with less skill.
Those readers interested in a more in-depth discussion of neural nets will find it in a new page I have added to the probability section of this blog. It deals with Bayesian networks used to create a probability oracle using machine intelligence.These are not the same as neural nets as they are studied in computer science but in my opinion model the brain at least equally well.
In addition to repetition there is a second way these brain circuits get strengthened. If the initial experience is one accompanied by shock or other extreme psychological states the imprint can be formed already strong. This is what happens with traumatic memories. Those suffering post-traumatic stress disorder from war, child abuse, or other highly charged events are literally being recaptured by greatly strengthened patterns laid down in an instant. Something similar seems to occur on the positive side of life with peak experiences.
The act of learning lays down an imprint on the biological substratum of our neural nets.
This idea of energetic patterns imprinting themselves into our biology can be a very useful one for understanding a number of otherwise hard to understand aspects of our cognitive and emotional experience. For example, the obsessive compulsive suffers from circuits having been strengthened to the point that they fire even when they are maladaptive in the current environment. Another example is how these circuits once they are engaged tend to run their course, which helps explain the physiological underpinnings for what is recognized in psychology as life scripts, mindless loops, and semi-automatic sub-routines. The same dynamics can also be recognized in sports as the skill of riding a bicycle, jumping a high bar, or what not.
Understanding imprinting is a sort of update to seeing ourselves as composed of the skandhas. These circuits are among the parts of the collections by which we recognize ourselves as ourselves. Changing ourselves involves not just an act of will and moral courage but also an often long and difficult journey through retraining electrochemical habituation. Recognizing this we should not beat ourselves up when we fail and we should be grateful for even the smallest increment of getting better.
Psychiatric medicine for depression, when it works, does so ultimately by altering the neurotransmitter soup by which the strength of such circuits are maintained. In this case a chemical level of manipulation is used to effect the chemical nature of the imprinting. Of course, not all medicines being widely used in our culture in such a fashion, however unconsciously, are coming from a psychiatrist’s office.
I believe meditation is also able to do this rewiring. It is a scalpel where most drugs are a sledge hammer. It is capable of using the calm depths of shamatha to power the charge that surrounds vipassana. With practice and over time the skill develops both in starving some circuits – as we pray “may anti-dharmic thoughts cease” – and creating powerful learning and healing encounters around compassion and wisdom as if they were mini-traumas of our own choosing.
Instead of being a puppet of chance and circumstance we have some degree of control over how our minds work. All people are involved in these same processes all the time, though with varying levels of skill. What organizes our ongoing efforts at pruning and strengthening these circuits of the mind are our most deeply held values. They color our every experience by adjusting their weights, their probabilities. The advice to a hot-head to count to ten before giving vent to their anger is a neurological technique for diminishing the auto-pilot nature of going off the handle. In other words, restrain a bit now and in the future it becomes more likely that you will be able to exercise restraint again. Exercise restraint in dealing with small upsets and you increase the likelihood that you will be able to exercise restraint when larger triggering events occur.
Remember that memory is not a playback of a perfect duplicate of the patterns but a re-creation. We embody a certain openness or space in which things can change if we do not keep them frozen. Those who work with traumatic memories know how reframing one can change the whole characteristic appearance of the post-traumatic symptoms. This is what reductionists miss who see in all this neuro-technology of imprinting energy patterns on biochemical circuits nothing but “mindless” stimulus and response. They miss the freedom this spaciousness provides.
Which brings us to the question of who should be authorized to form and manipulate a human being’s imprinting? With imprinting added to our cognitive tool-belt we are in a good position to understand the difference between teaching and manipulation. We will take a look at that next week.