Thursday, December 22, 2016

The Brain, Sequential Memory - Long Term Memory

COLLECTIE TROPENMUSEUM Een uit kinderen bestaand gamelanorkest TMnr 20018403
Children Playing Gamelan Music from Memory


The second type of memory is long term memory. They are formed from basic memories known as recognitions. The formation is done through repetitive playbacks of similar IFPs (impulse firing patterns) in the brain. Each replay of similar IFPs is a recognition. The brain consolidates the repeating recognitions into a distinct long term memory. So one difference between the two types of memories is that recognition is approximate and general while long term memory is more definite and specific.

Brain Circuits are reinforced Through Repeated Use, Simulation of IFPs.

When one has practiced riding a bicycle enough times, one acquires a long term memory of riding. Being able to use chopsticks is also a long term memory. Reciting the Pledge of Allegiance by heart is yet another. All memories involving the usage of muscles are long term memories. They come through practice, which is also repetition. These memories are not stored in the brain, but are played back in some dynamically formed memory circuits.

The formation of long term memory circuits can be explained in terms of the F.A.R.E. framework. The F.A.R.E. framework stands for feedback, adaptation, resonance, and equivalence. It is the basis of many complex natural phenomena. In this case, the wiring of long term memory circuitry comes from adaptation of brain structures to repeated playback of similar IFPs.

Mouse cingulate cortex neurons.jpg
Impulse Firing Patterns (IFPs) are patterns of impulses firing from neurons to neurons.
Mouse Cingulate Cortex Neurons. CC BY-SA 2.0, Link


First, what is adaptation? Adaptation is an active reaction to repeating stimuli. Some psychologists call it learning. The “active” part refers to the energy supply a system has for its action and reaction. Blood and nutrients are energy sources to brain cells. They provide energy to neurons so those cells can react to impulse inputs actively, like amplification or reduction or transformation. That is different than passively transferring or dissipating the impulses in their propagation. Besides actively transforming incoming IFPs, brain structures themselves can and do change, adapting like all living systems do to environmental inputs. The lungs of mountain people are bigger than those of plains people. The skins of tropical people are darker than those of polar people. Both show energy-backed organs adapting actively to repetitive environmental stimuli, and resulting in the organ’s structural changes.

Why do organs change their structures during the process of biological adaptation? And towards which direction do they change? The answer to both questions is economic advantages. Economics drives changes. The direction of change in evolution is towards where it is more economically advantageous. Economic forces are like the transition probabilities of a stochastic process. Stochastic states with economic advantages have a greater probability of becoming, therefore the final equilibrium will favor those states. In other words, evolution pathways follows economic currents. They flow towards and settle down in certain niches, which are states of greater economic advantages. Active systems striving for economic advantages will thrive better than those that do not. Seen from hindsight, systems that survive an evolutionary process are the ones that have made changes to gain economic advantages. In the case of long-term memories, the brain’s adaptation to repeating IFPs is to form neural circuits that are highly efficient in playing back the IFPs. This efficiency advantage allows less energy consumption in the reproduction. Those neural circuits are memory circuits because they playback similar instances of IFPs. Also, efficient playback of IFPs is just one type of economic advantages. There is another type that will be discussed later.

Finance Markov chain example state space.svg
Stochastic Process, Markov Chain with State Transition Probabilities
By Gareth Jones - Own work, CC BY-SA 3.0, Link

Besides active adaptation, passive reactions can also shape the course of evolution. Passive reactions take place in objects that do not have or use their own energy supply in response to input stimuli. For example, the formation of trails in wilderness is a passive reaction on the part of the wilderness. First, the wilderness is covered with vegetations. Then trails appear as the ground and vegetations give way passively to the trampling hikers. The trails may keep evolving, turning into roads or streets or highways. However, it is the people using these pathways that actively adapt themselves and these pathways to change. The wilderness just passively gives up the space, which is also a resistance to the active trailblazers.

Natural Evolution of Shortcut Pathways.

Trail formation in wilderness is quite similar to memory circuits formation in the brain. The traffic of hikers causes the wilderness to change and evolve. The traffic of IFPs causes the brain to change and evolve. Both originate from movements that have repetitious patterns, and both exhibit memory characteristics. The word routine comes from the word route. By going through a routine, one is equivalently re-enacting a memory. For example, going to bed at night is a routine and a memory replay. It includes a sequence of changing clothes, brushing teeth, saying good night, turning off lights, and so on. It repeats nightly without much variations. The elements and order of the sequence may vary from person to person, but each person has a fixed set of actions and order. The brain remembers the sequence so the actions are carried out automatic once they get started.

A physical road can also have memories. For example, a traffic accident can cause a memory effect. In highways where traffic volume is high, cars coming near an accident spot will slow down and stop because of the blockage. But even after the accident blockage is removed, cars coming later to the scene will still repeat the same stop and go movement as if the blockage is still there. That is a memory effect. The stop-and-go pattern can only be erased when the traffic volume is reduced or rerouted. This is one aspect of the dynamics of congestion. It can happen in any circulatory system. When having a cold or flu, we cough and sneeze repeatedly. These are similar symptoms of congestion.


Back to the active adaptation process in memory circuits formation. Active adaptation is largely directed by forces of economic advantages. Generally there are two types of economic advantages: efficiency and growth. Efficiency (or economy), mentioned before, is a means to saving resources or reducing expenses. If a regular rate of exchange in a transaction is one unit of output for one unit of income, then an efficiency push will change the balance to less than one unit of output for one unit of income. On the other hand, growth (or prosperity) is a means to gaining resources or increasing income. If a regular rate of exchange is one unit of output for one unit of income, then a growth pull will change the balance to more than one unit of income for one unit of output.

Numerically speaking, if 2 workers in a factory produce 1 car in 1 day, then an efficiency push will drive the the factory to have less than 2 workers to produce 1 car in 1 day, or produce 1 car in less than 1 day by 2 workers. On the other hand, a growth pull will direct the factory to produce more than 1 car by 2 people in 1 day. These two economic forces can apply to other economic factors also. Besides time and labor, the factors can be usage of equipment, space of work area, sales channels, market volume, etc.

How do economic advantages apply in the adaptation of the brain? The adaptation process changes a jungle of neurons and synapses in a baby’s brain into networks of memory circuits later. That involves income and expenditure of energy. So economic advantages can apply in those transactions. If X synaptic connections use Y units of nutrients/energy to playback a sequence of IFPs, then an efficiency push will change the neurons and neural structures to either reducing the X or the Y. For example, neuroplasticity, or Hebb’s Rule, states that “... When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A's efficiency, as one of the cells firing B, is increased…” This neuroplasticity is a case of cellular restructuring to achieve a reduction of energy expenditure in impulse transmission, which is reducing the Y. Then, during sleep and during adolescence (in a larger time frame) memory circuits go through consolidation by synaptic pruning. That is cellular restructuring to achieve a reduction of synaptic connections, or reducing the X.


The growth pull, the other type of economic advantages, will alter brain structures by building up memory circuits that will obtain more resources (energy income, synaptic connections) than they spend on the playback of IFPs. Obviously, neural networks involved in the digestive process fall under this category. In those networks, nutrients obtained from the mechanical and chemical actions of digestive IFPs are amply redistributed back to the brain and nerves, making those circuits grow and strengthen.

Also, the growth pull can target incomes other than nutrients. It may reinforce memory circuits for the taste, like sweetness or saltiness, rather than the nutrition of food. For example, some regional ethnic foods are prized by locals but not by visitors. A southeastern Asian may not like the cheddar cheese the first time he visits America. A Canadian probably cannot stomach the Chinese stinky tofu even if he has lived in China for some time. This is due to memory circuits accustomed to the taste of native foods are not developed yet in the visitor’s brain. Once the visitor has tried these local foods a few times, he may be won over by the taste. Then he will eat them more often like the natives do. By then the acquired-taste memory circuits are established in his brain.

Not only tastes, comfort induced by music, massage, drugs, etc. can also be targeted as desirable income for neural circuits. These are pleasurable sensations linked directly to the secretion of certain hormones and neurochemicals, which can alter and be altered by the running IFPs among neurons. The presence of such hormones allow growth pull to form neural circuits that will target more of these hormones. Similarly, the seeking of success, power, beauty, love, etc, may all be associated, perhaps indirectly, to some hormone production. And growth pull will create circuits to pursue higher yields of those desirable chemicals as well. Videophilia, sinophilia, neophilia, etc. are words describing this pattern. These philias are love rising from thoughts in some specific memory circuits that specialize in seeking niche rewards of movies watching, Chinese culture, or new things, etc.

Generically speaking, any information (or IFPs that fire in neural circuits) that can trigger the release of neurochemicals, or causing some re-balancing of neurochemicals, may become a source of growth for memory circuits. Pleasure hormones are not the only cause and target of self-fulfilling circuitry. Information that can satisfy curiosity, fantasy, mental urges, or even routine dealings, may have such an effect as well. The smartphone, a device that provides instantaneous information to its user, shows how desirable personalized information can be, and how attached we are to it. We naturally remember to take the phone with us wherever we go, even to where we eat or sleep. The memory circuits of using the phone can be so well established that a sudden loss of the phone will be a rude awakening, akin to the shock of having lost a loved one. That kind of loss is like giant sinkholes appear suddenly in busy highways, causing paralyzing congestion to the traffic.


Finally, the dark cousins of desire - fear and anxiety - can also trigger hormonal releases and attract growth pull to form new memory circuits. However, fear is normally undesirable so the new circuitry can prosper only if their function is to reduce or transform the fear IFPs rather than to increase them. Kind of like a natural relaxant. There can be two ways to do this: a quick reactive one and a slower meditative one. The quick reactive circuits harbor IFPs of anger. These IFPs aim at eliminating fear and threat IFPs quickly (fear and threat of pain or loss or unfamiliar situation). They trigger thoughts of offensive attack. The slow meditative circuits house IFPs of reasoning. Those IFPs work to transform fear IFPs into safe-feeling IFPs. They trigger thoughts of defensive security, like ideas about protecting the body’s safety with some material or insurance. Either way, they are counteractive circuits that produce negating IFPs against the fear IFPs.

The word phobia describes this pattern. People with phobias habitually dwell on fears and their countermeasures. For example, xenophobia describes a pattern of thoughts from memory circuits that are 1) primarily formed by repeatedly hearing and imagining how bad foreigners are (fear, anger) and 2) derivatively formed by repeatedly hearing or imagining how great it will be to seal off the border or something else (security). In Hinduism, these thought patterns are called Maya (illusion). In Buddhism, the Heart Sutra labels them as Kon (emptiness). They are thought patterns that match only an artificially selected small sample of the reality, not the natural ever-changing whole reality.

In post traumatic stress disorder (PTSD), victims may have recurring nightmares about a trauma. But they may not remember the actual trauma itself, or remember it partially or falsely. It is not that they forget about it. They do think about it a great deal. But by thinking about it, or rather by remembering around it, their brains develop counteractive memory circuits that playback imaginary IFPs to ward off the principal trauma-fear IFPs, to sweep them under the rug, and to prevent the painful trauma IFPs from playing back truthfully.

If the derivative memory circuits do not produce enough counteractive IFPs, of thoughts of seeking safety or fighting back, to fully defuse the fear IFPs from the primary memory circuits, then what can happen? It may happen that the remaining altered fear IFPs will circulate in neural networks as a sensation of anxiety. In other words, anxiety is a veiled projected fear of what may happen based on or related to what had happened. Very young children do not know anxiety until they have experienced some recurring punishment or separation from parents. 初生之犊不畏虎, as the Chinese saying goes: a newborn calf fears no tiger.

Recurring anxiety IFPs can induce a formation of tertiary memory circuits of yet another kind of IFPs. That IFPs can be either to react again or to yield. The yielding IFPs are thoughts of capitulation and sensation of depression. Depression is a feeling of heaviness, of hopelessness and giving up against the recurring and accumulating anxiety. If such tertiary memory circuits do grow and expand, to where they can be triggered directly by input IFPs of normal activities in daily life, then it becomes a case of clinical depression. The sufferer has lost “the spirit” to act and react to almost anything, but can only feel the weight of anxiety dragging him down. On the other hand, the reacting IFPs are thoughts of making changes, to turn things around for the better to get rid of the anxiety. These thoughts have more stamina than short-lived youthful fancies, as the recurring anxiety has longer life spans as their triggering source.

Whether they are Maya (illusion) or Kon (voidness), these thought patterns are imaginative IFPs taking place in memory circuits of the physical brain. Spiritual teachings and counseling often aim at helping one to understand them, and to work around one’s own imagined securities and insecurities. This is similar to psychotherapy. They can go by different means - verbal, ritual, physical, social, spiritual, or pharmaceutical - but the goal is the same: to establish in the brain memory circuits of desirable IFPs like joy and happiness, and to disrupt memory circuits of undesirable IFPs like anger and anxiety. It can be the other way around also, depending on the circumstances and intentions, like the story of Darth Vader in Star Wars. Either way, the building up of memory circuits will require repetition of similar activities, therefore a long incubation time.


IFPs in one memory circuits can be amplified or reduced by IFPs in another. In some extreme cases, amnesia occurs after an acute trauma. That amnesia is not a product of counteractive IFPs from a derivative memory circuits, since amnesia is actually forgetting rather than a coverup. A possible scenario for this is that some unusual damage in neural transmissions has taken place, causing paralysis in the traffic of neural impulses. Typical traffic accidents in roadways will result in a memory of stop-and-go movement for cars in the vicinity. But amnesia is perhaps like an accident of great complexity or severity that traffic cannot go in or out of the vicinity. We will look into the phenomenon of forgetting more later.


One more note about economics. Although economic advantages are the primary drivers of active adaptations, they are dynamic themselves, not static. Any particular advantage does not and cannot continue its trend of self-fulfillment forever. Sooner or later it will reach a point where the income and expenditure of resources are changed fundamentally. That will trigger a phase change in the economics. From that change of balance comes cataclysmic transformations that exist all branches of evolution. They are called Punctuated Equilibrium described first by paleontologists Stephen Jay Gould and Niles Eldredge. In the brain, this phase change is called paradigm shift or a change of heart. It is common to hear stories like Mary breaks up with her steady boyfriend John and dates somebody else, or John gives up music and becomes a carpenter, or in a larger scale a country adopts a new policy or changes its regime. Such changes are manifestations of new order of economic advantages and memory circuits. From time immemorial there are observations that changes never stop. No equilibrium is ever permanent. The Buddha called it Impermanence. Fairy tales mask it by ending a story with the line “and they lived happily ever after”. Acute observers see it not as an ending but a phase change, more like “and they lived together, but that’s another story...”


So, with these background information about active adaptation and forces of economic advantages, let’s review the formation of dynamic long-term memories in the context of F.A.R.E. framework.

F: Feedbacks

When active systems interact with each other, they continuously provide and receive feedbacks. Before birth, a baby has no memory of the external world other than his interactions in the womb with the mother, which are probably primarily about receiving nutrients and expelling wastes. After birth, he senses all kinds of activities from within and without his body, and he acts or reacts to all that. These actions / reactions trigger IFPs to fire in his brain. Reciprocally, his actions / reactions cause other beings in his surrounding to react, making their brains to fire IFPs as well. All these physical interactions and IFPs are informationally feedbacks from one to the other.

A baby cries when it gets a feedback signal of hunger from his stomach. A mother feeds the baby when she gets the feedback signal of the baby’s crying. The baby stops crying when he get the feedback signal of milk in the mouth. The stomach stops signaling hunger to the baby’s brain when it gets the feedback signal of milk coming in. The mother relaxes when she gets the feedback signal of baby stops crying. And so on. More importantly, when some feedback pathways connect up into a loop, so some feedback information can propagate back and forth indefinitely, then repetitive interactions will come into play, and routine memories will establish and manifest.

Formation of Neural Circuitry by Feedbacks

Baby feeding is one example of feedback loops. It happens regularly between a mother and her baby. Talking, playing, learning are other kinds of feedback loops. Feedback loops are usually broken up when one party in the loop becomes passive like a rock. But this is manipulable as it can seemingly be a feedback loop of only one active system. A child can pretend to be somebody and something else. When he plays with a toy, which may be a passive plastic form, he can get feedbacks from the toy via his own imagination projected onto the toy. By splitting his imaginations into two and establishing feedbacks between them, he can discover, for example, shapes and structures from a LEGO toy. His imagination about the lego pieces become a source and destination of feedback to his other imagination about houses or bridges.

Playing with toys is different from Interacting with living beings. Toy-playing is an interaction of the type of autonomous self feedback. While interacting with real living beings is of the type of bilateral mutual feedbacks. The second type of interaction involves more active systems than the first. Naturally that is more complicated, but necessary for the growth of social intelligence in the participant(s). As a side note, economic advantages in bilateral-feedback situation will drive one participant to make the other party more predictable to understand and control. People familiar with the dating game, corporate ladder game, war game, or other games, are no stranger to this game-play manipulation. But as far as memory circuits formations go, the outcome of social interactions can produce divergent results. Some people become shy and prefer toys over company. Their memory circuits of social interactions are closer to those that play security IFPs to mask off fear IFPs. Others become gregarious and prefer company over gadgets. Their memory circuits of human interactions are similar to those that play pleasure IFPs - the more the merrier.

E: Equivalence

Part and parcel to physical interactions among humans and animals are the firings of IFPs in their nervous systems. These IFPs are experienced mentally as urges, cognitions, recognitions, or memories. It is a phenomenon of equivalence that equates physical neural firing of IFPs to informational mental perceptions. For example, a mother’s hand touches a baby’s arm. The baby’s senses trigger some IFPs to fire in his brain by this event. That IFPs are equivalent to the baby’s perception of the mother touching him. Conversely, if the baby dreams of his mother touching him that same way again, then the equivalent IFPs are fired again in his brain.

When an IFP is played in the brain the first time, it is called a cognition. When it is similarly played back a second time, due to coincidence or to some routine in the feedback stream, then it becomes a recognition, or a simple basic memory. When it is replayed back similarly over and over, then it merges into a long term memory.

A: Adaptation

Repetitive playbacks of similar IFPs cause the brain structures to change and adapt. The adaptation results in the formation of neural circuits of long term memories. Economic advantages tailor the formation of these circuits to be either more efficient in playing back the IFPs (efficiency push), or more prosperous in obtaining correlated IFPs or chemicals (growth pull). The IFPs fired in these circuits are equivalent to long term memories. For example, we can internally recall a song or a math formula or the face of someone after we’ve heard or seen it long enough, with little or none of its physical presence to remind us. This internalization of IFPs playback without external triggers marks another difference between a long term memory and a recognition. Recognition requires external sensory inputs to trigger their playback, and it may or may not have specific neural circuits. On the other hand, long term memories can be triggered with or without external sensory stimuli, but they do have specific memory circuitry. Playback without external trigger is possible when feedback pathways are internally established between the long term memory circuits and other neural networks in the brain structures.

R: Resonance

Resonance is a major factor in the formation of another type of memory - the associative memory. We will go into that in the next article.


There is another name for long term memories that can better describe their characteristics. That characteristics is sequence. Long term memory circuits can playback specific IFPs efficiently in a peculiarly manner. This peculiar efficiency has to do with a high ratio of output to input in temporal order. Suppose that IFPs can be partitioned into sequential segments like chapters of a movie or novel. The efficiency of long term memory circuits is that they can playback the whole sequence of IFPs from an input trigger of just one segment of the sequence. This input can come from sensory stimuli externally, or from IFPs fired elsewhere in the brain by way of resonance or feedback. Here are some examples.

1. Singing. By given some beginning notes, most people can sing out the rest of a familiar song, or at least some parts of it.

2. Typing. After much practice, a typist can type out the sequence of keystrokes automatically from a glance of the words. This enactment of a sequence initiated by a general shape or label is similar to reciting a poem by hearing its name or some beginning words.

Practicing the Violin.

3. Routines and skills. Cooking a meal, shooting basketballs or kicking soccer balls, riding a bicycle, sawing boards or hammering nails, are all skills gained from routine practices. Practiced enough times, the recall of the routine becomes automatic and subconscious, as that is less energetically expensive than conscious effort. Put it in an analogy. Skill IFPs are software. Memory circuits are hardware. Practicing and the brain’s adaptation to practicing are incarnation of software into hardware. In olden days, a master does not train his apprentice by explaining the work, but by having the apprentice observe and imitate what is done. “Practice makes perfect” is a tried and true way of building skill memory circuits. Explanation may give the novice theoretical knowledge, but it is no match to memory circuits for carrying out sequential movements economically.

4. Accent. The Japanese pronunciation of the word beer is “beeloo”. This is an effect of some memory circuits that automatically playback the sequence of sounds in Japanese with an ending vowel (except for words that end with the letter n). This sequential playback of an ending vowel is so hardwired that the Japanese have a hard time omitting it, hence their particular accent. The American pronunciation of the Chinese word “good” (好) is “how” or “hau”. But the tonal stress is not right. This is also a memory effect of some practiced American tonal sequences superseding the unfamiliar Chinese ones. Likewise, most old habits can become oddity when applied in a new environment. Faux pas in table manner, social etiquette, figure of speech, etc. are common when one travels abroad. They are all symptoms of some vestiges from old memory circuits adulterating the formation of new ones.

The phantom limb syndrome is a bizarre case of “accent” in neurophysiology. Some patients who have lost their limb through amputation can still feel sensations in the missing limb! This again is probably due to some obsolete sequences of IFPs being automatically played out in some memory circuits. But there is a therapy to correct this. It basically attempts to develop new sequential memory circuits to override the old ones.

Dr. Ramachandran's Mirror Box Therapy for Phantom Limb Pain.


The examples above show that automatic sequential playback of IFPs is the hallmark of long-term memory circuits. Neuroplasticity, or Hebb’s Rule, shows especially that neural restructuring is tied to sequential timing in the impulse firings between adjacent neurons. So, to highlight this characteristics, long-term memory is called sequential memory here. It is very remarkable that a sequence of IFPs playback can roll out on its own in the neural circuits. What is in the music box that can play its music? What exactly are the structures (or dynamics) of sequential memory circuits that can playback IFPs sequentially? Perhaps the answer lies in the phenomena of repetition, since that is part of the genesis of sequential memory circuitry.

Mandelbrot detail3
Fractal, Mandelbrot Detail

Maybe the circuit structures are similar to fractals. The images of some fractals, such as the Mandelbrot Set, are generated by repetitive feedbacks of complex numbers through a simple math formula. These fractals are self-similar in that a portion of the image anywhere looks similar to the whole image. That makes reproducing the whole from a part easy, which sequential memory circuits can do with an IFP trigger. However, individual fractal images are flat. There is no sequence in them. How can that reflect the sequential aspect of memory circuits? So maybe a closer match is the form and formation of DNA molecules. DNA certainly exhibits characteristics of memory as it encodes the physical traits of a species and transfers that from one generation to the next. The sequential combinations of the chemical alphabets - A,T,G,C - are what encode genetic information. If the synthesis of DNA involves repetitive feedback interactions between the DNA molecules and some other molecules, like that between one memory circuitry and another (or between IFPs), then we may have some clues about the spatial structures of sequential memory circuits.

Can the Structure of DNA Molecules Provide Insight Into the Structure of Sequential Memory Circuitry?
DNA Split By US Department of Energy - DOE Human Genome project, Public Domain, Link


Although speculating about the structures of memory circuits is interesting theoretically, there is a more pressing practical issue about memory and communication. Memories, as replays of IFPs sequences, are likely to be different in different people. There are so many variations in people’s life experiences, and therefore so many variations in IFPs sequences fired in different brains. The chances of having a same sequence of IFPs in two people are perhaps smaller than winning a super lotto. Even for twins who are eating a same meal at the same time, they will still likely have different experiences of that event. That means different people have different memories on just about everything. Then one question arises. Do people with different memories understand things and each other the same way? Apparently not much. In popular psychology, many books on men-women relationship, such as the one Men Are From Mars, Women Are From Venus by John Gray, showcase problems of misunderstanding between couples when they communicate. This problem of misunderstanding due to different memories and experiences is so common that it happens not only to couples, but to people in all walks of life. Beside the gender difference, age, profession, social status, moods, lifestyle, diet, etc. can all be factors that cause miscommunication and misunderstanding.

Differences in Communication. Men Are From Mars, Women Are From Venus.

Political discourse is a glaring example of miscommunication. The way one party debating the other is like chickens talking to ducks. So how do people come to common understandings given that they all have different memories to begin with? It may seem strange, but the fact is people do understanding each other at least to some degree. Therefore there must be some similarities in the memories of different people that can be the basis for mutual understanding, even if the total sequences of memory IFPs are all different.

For example, the meaning of the word mother will be different to different people, because their interactions with their respective mothers are different. But there are similarities in those interactions, such as feeding, dressing, cleaning, and bathing provided by a mother and received by a child. Those similarities are the common grounds where different people can come to an understand about what a mother is. If such common grounds do not exist for them, then misunderstanding is bound to happen when the topic of mother is raised.

A father asks his rebellious teenage son why does he not listen to his mother? The father is puzzled because his wife seems to him a loving and caring mother to the son. The son replies “did you listen to your mom when you were at my age?” And the father suddenly understands his son better because he too occasionally did not listen to his own mother.

Modern couple (or communication) therapy treats miscommunication problems by finding or building common grounds in the two sides’ memories. Miscommunication can happen on any topic, and people may take common understanding of things for granted. Actually, mutual understanding or common sense is not common, simply because there are far more ways to be different than the same in thinking and remembering. And even if common grounds exist in two people’s memories, there is still no guarantee they will come to an agreement. Examples are abound. Ask two economists what is inflation, or two mathematicians what is algebra, or two cooks what is cuisine, or two buddhists what is buddha nature. The answers will have vast differences despite the common lingos. An artist can no more expect his audience to understand his work the way he intends it than the audience can of the artist. So ultimate understanding is not likely, but realistic understanding is. It is all about bridging common grounds and leaving unbridgeable uncommon grounds alone.


Amnesia from Removal of Hippocampus. The Strange Case of H.M.

Back to the forgetting aspect of memory. In terms of the mechanism of sequential memory circuitry, how does amnesia occur? Since a memory is a replay of certain IFPs in sequence, then the forgetting of it is a disruption of that replay, either in the sequence or in the patterns of impulse firing. This can be illustrated with an example.

A man habitually comes home and puts down his keys on a desk before he goes into the kitchen and opens the refrigerator to see what’s inside for a snack. One day he gets his snack from the refrigerator, and then is surprised to find that the keys are not on the desk. He has forgotten where he left the keys.

There are at least 3 possibilities that can cause disruption in routine IFPs and create a short episode or a long saga of amnesia: 1) sensory distraction, 2) chemical alteration, 3) neural structural change.

1) Sensory distraction: Before putting down his keys, the man may see or hear or think of something that makes him change his course of action. In that alternate, non-routine course of action maybe he leaves the keys in his coat pocket or on the TV. But when he finds the keys not on the desk, he becomes aware of his forgetting. This perception of forgetting is due to the discrepancy of the routine memory reminding him the keys are on the desk and the reality that they are not. The playback of the routine sequential IFPs is so automatic that it overrides the playback of non-routine IFPs, and so blocks the memory of where he actually puts the keys. The amnesia is specific about the keys being missing. He has not forgotten about other things. To remedy this, the man needs to retrace his steps, starting from where he gets back home. This can provide a better chance for that non-routine IFPs to playback and lead him to the keys. Or he can just search everywhere by brute force to find them.

Children before a certain age and adults after a certain age are prone to be forgetful by sensory distractions. Some attribute such forgetfulness to short attention spans. But that is using the symptom to explain the cause rather than the other way around.

2) Chemical alteration: There are lots of chemicals in the brain that support its functions. When the balance of chemicals in the brain undergoes significant changes, such as a rising level of certain hormones or alcohol, a man will perceive and remember things dramatically differently. Whatever the cause might be (they could be triggered by sensory impressions or thought patterns), once the brain’s chemical balance has shifted, the memory circuits will not fire their routine IFPs the same way as before, because neuronal firing of impulses are not only conditioned by the synaptic connections, but also by the amount of neurotransmitters and nutrients and hormones present, which can all change due to the chemical balance shift. Examples of this type of forgetting can be alcoholic blackout, stage fright, brain freeze on a job interview or during a test.

Chemically-induced amnesia can also happen during euphoria. Here is a journal entry from a website on euphoric experiences: "I started to feel the effects kick in. I felt euphoric and very happy. I had a big urge to just go out and do anything at all without a care in the world. I couldn’t really think because all I could do was feel. Just feel happy and giddy. I cleaned my room and was pretty much chain smoking. I wrote in my journal in an attempt to record my experiences. (I will get to that later). I don’t remember much of it but I’m sure I spent quite a bit of time just playing around with random knick knacks in my room."

When the IFPs in a routine memory circuits are altered chemically, the man in the example not only may forget where he left the keys, but also that they are typically left on the desk. The sequential IFPs can be so scrambled that the routine itself is forgotten, somewhat like a deer caught in the headlights.

Another example of chemically induced forgetting is dream recall. Some people do not remember their dreams when awake, others do. The chemicals in the brain have different levels in the sleep and the wake states. That difference can make dream IFPs elusive to replay in memory circuits during the wake state. However, if one goes back to sleep right after waking up from a dream, and allows the chemical balance to lean back towards the sleep state, then one may go back to dreaming. So remembering dreams is quite feasible when one is about to wake up from sleep. At that point the transition of chemical balance in the brain is still on-going. While it can replay some of the dream IFPs at that stage, the brain can also only replay some of the wakeful IFPs but not others like the skill of proper handwriting. The handwriting of a dream journal can be full of errors - spelling errors, homonym errors, grammar errors. In Freudian terms, the homonym errors reflect the working of the subconscious.

Study Reveals Chemical Changes During Sleep.

3) Neural structural change: Some sequential memories do fade with age. Poems we used to recite easily can become foggy over time. By the age of 80, a man will likely have some decline in the neural structures. The brain might shrink, and the neurons might have plaques and tangles. When neural structures show significant changes, such as those with Alzheimer’s Disease or Dementia, then forgetfulness is prominent. This is still due to routine IFPs not being played back like before when the memory circuits were in different conditions. The contributing factors here are the changes in neurological hardwares instead of chemicals. In this type of amnesia, forgetting where the keys are is not so serious. Serious will be when the man doesn’t know his close friends or relatives anymore. The final stage of degradation will be when the sequential memory circuits responsible for breathing or digestion or immune defense systems become eroded. By then the life of that man is approaching a global phase change.

Dr. Lara Boyd: the Brain Changes All the Time


When we talk about memory, we also mean remembering things of the past rather than doing things like typing or singing. Naturally so. We remember having lunch 2 weeks ago, and we remember the first date with someone we are in love with. Strangely, it is very hard to remember what we ate for lunch two weeks ago but easy to remember what we did on the first date with our beloved. Why is the second one easy but the first one not? After all, both memories are replayed in some repetitive manners. We eat lunch everyday. And we may reminisce about what happened during that first dream date maybe weekly if not daily.

It turns out there is a difference in recalling these two types of events. They are not the same as automatic replay of sequential memories.

The particulars of a meal eaten weeks ago are hard to remember because they are not repetitive. They may change from sandwich in one day to salad the next day and to noodles the next, and so on. And variations do not sink into sequential memory circuits because they are not similar instances. If all lunch meals consist of exactly the same food day after day, then it would be very easy to remember. Or, if there is a pattern in the variation of lunch menus, say Monday is always sandwich and Tuesday soup and salad and Wednesday fried rice and so on, then it is still not difficult to remember. We can use the day of the week as an index to dig it out. But such patterns are usually not adopted by people with their meals. So without a repeating pattern in the food items, chances are small that the IFPs of a particular day’s lunch can be replayed spontaneously.

However, the replay of the first-date IFPs, unlike the eating-lunch IFPs, can be triggered from multiple memorable sources. For instance, the pleasure of looking at the face or hearing the laughter of the beloved is memorable. So that can be a trigger. A strong resemblance of a shirt or a gesture to the one in that date is also memorable. That can be a trigger too. The more source triggers there are, the higher the probability that a triggering can take place. And once triggered, the sequence of the first-date IFPs will more or less be replayed in a similar order as the original one. So it is easier to recall what one did at the date.

This is basically associative memory. It can also happen in remembering the lunch items eaten two weeks ago. If some memorable events, bad ones especially, took place around that lunch time and could be associated with it, then it will be easy to remember what was in that lunch. For example, too much soy sauce was in the fried rice, or somebody ate part of that delicious grilled cheese sandwich without one’s consent, or maybe it was an unusual dessert baklava added to the meal that made one wanted more. If a lunch has as many prominent associations to it as that of the first date, then the two events should both be easy to remember. But obviously a first-date has more prominent associations than a weeks-ago lunch. Plus, the first date is more pleasurable to recall than eating a lunch so there is also the growth pull factor that can build extra neural links to that.

We will look into the associative memory in more detail at the next installment. For now we just describe it as a memory IFPs being triggered to replay by some other IFPs that bear no sequential relationships. The triggering happens by feedbacks or resonance.

One last note about sequential memory is that it can be both helpful and unhelpful. The formation of sequential memory circuits is to gain economic advantages. That is good. But the downside of gaining economic advantages is the loss of flexibility. The more flexible a neural network is, the less efficient its sequential circuits will be. And vice versa, the more efficient the sequential circuits are, the less flexible the neural networks will be. It is similar to the Heisenberg’s Uncertainty Principle in atomic physics. The more the position of an atomic particle is certain, the less its velocity is known, and vice versa. So if one has a fixed sequential memory circuits on eating a particular meal, he will be less flexible in remembering other events. There was a joking commentary about the students in two neighboring universities. A Harvard nerd is someone who knows nothing about everything, while an MIT geek is someone who knows everything about nothing. One is Miss Flexibility, the other Mr. Speciality.

Contemplating on plants. From buds to leaves to branches to buds again. Is that a cycle of efficiency and flexibility, of consolidation and expansion, of Autumn and Spring, of yin and yang?

No comments:

Post a Comment