Behind the Scenes of The Brain Show

by Zeev Nitsan

  The Yerkes-Dodson Law:

  The Connection Between the Level of Arousal and the Level of Performance

  Forgetfulness at the Service of the Genes

  The blunting of memory takes place naturally with regard to labor pains. It seems that the oxytocin that is discharged during labor and induces contraction of the uterus muscle blunts memory with regard to the aspect of physical agony in labor. Some may say that by doing so, it lessens the worry about additional labors.

  Desirable Blunting of Memory

  The painfully glaring lighting of memories that derive from traumatic experiences may be dimmed through the use of drugs that belong to the pharmacological family of the adrenergic beta-blockers. Such drugs turn down the sounds of the emotional soundtrack attached to the experience and soften the scraping of the traumatic experience. Such an effect is possible because the activity of adrenaline and noradrenaline, which are discharged in stressful situations and encourage emotional arousal that deepens the traces of memory, are blocked.

  On the other hand, it is possible to intensify memory or to deepen its traces in the substrate of brain cells by giving adrenaline or other substances that imitate its activity.

  There is the “blessing of forgetting”—a “forgetting pill” that is given to a person who has experienced a traumatic event and is intended to erase painful memories from consciousness can be compared to a drop taken from the legendary River Lethe that can erase past memories.

  The opportunity to get rid of “painful” memories we are all doomed to have was tragically seized upon by the unfortunate lovers in the movie Eternal Sunshine of the Spotless Mind.

  Medications that will enable us to broaden the limits of our memory raise the concern that we might become trapped under an avalanche of details that will roll all over us at any given moment. Will we become prisoners of overly detailed memory recordings that will compromise our ability to process information and plan our future moves? Will all veins of every autumn’s leaf become engraved in our memory, as in the story “Funes the Memorious” by Jorge Luis Borges? Will the effect of the sometimes-blessed oblivion be doomed to disappear from our life, although it has a survival role in the adventurous book of the evolution? The frail interrelation between memory and oblivion might be interrupted and make the brain deal with a challenge it has not encountered before.

  Universal Pattern of Memory Organization

  Four main activities are related to memory processing in our brain: encoding, storage, consolidation, and retrieval.

  Encoding is the acquisition of new information. Storage is the preserving of information. Consolidation is the middle stage, which combines encoding and storage features. Retrieval is the stage of recollection. Each activity is organized in our brain in a different pattern. It seems that there are similarities between the patterns of memory organization in the brain of human beings and other animals.

  Procedural memories (which encode performance skills of sequences of actions) are partly engraved in the DNA; thus, for instance, horse embryos perform galloping movements in their mothers’ uterus.

  Memory researcher Eric Kandel, who was greatly involved in studying the biological substrate of memory, chose an Aplysia sea slug, which has about twenty thousand neurons, many of which are visible. Kandel assumed that the nervous systems share similarities across all hierarchies of living creatures’ kingdom. He conditioned the sea slug so that its body being touched led to wincing of its gills and moving away from the area of stimulation. Afterward, he followed the recordings of the neurons’ activity. It was found that the intensity of the signals that pass between them doubled once the behavior was internalized.

  Kandel’s insights, based on his studies, aim to prove that there are many similarities in the pattern of information processing and encoding among animals along the height of the pyramid of evolution.

  Memory as Woven in a Nesting, Modular Pattern

  The neurophysiologist Charles Sherrington once called the brain a “magic loom” due to its ability to weave together multiple pieces of information as necessary. The footsteps of our memory are scattered—they are not located at a specific location in the brain but gathered and woven together into a coherent memory from different brain areas.

  Long-term memories have considerable preservation ability, inter alia, since their components are scattered and derive from different brain areas.

  Recollection usually has a nesting, modular nature. The nesting pattern of recollection tends to flow from the general to the specific (e.g., from a “trip” to a specific trip to the summer camp in the woods).

  The modular pattern of recollection relies on the fact that recollection is an anabolic process (a process during which a complex structure is formed from smaller, simpler units) that summons shreds of experience from various brain areas to the memory-composing workshop. These shreds of experience, once merged, become an overall memory experience.

  Remembering How to Forget

  Time weeds shades and sounds from the garden of our memories.

  The changing streams in the river of our life enforce a constant drift of oblivion, which shapes the route of our memory channels every day anew.

  A breakthrough in scientific research about the pattern of memory fading occurred when the researcher Hermann Ebbinghaus published his finding regarding the process of recollection. The “lab mouse” in Ebbinghaus’s study was Ebbinghaus himself. With Sisyphean persistence, he repeatedly memorized multiple lines of meaningless syllables, to the beat of a metronome, and followed the pace of their fading from memory.

  His findings showed that the curve of natural fading of memory is not linear.

  He found that about 40 percent of the syllables were forgotten about twenty minutes after memorizing. One day after memorizing, about 60 percent of the syllables were forgotten, and later on the pace became slower. A month later, he could still remember about a quarter of the syllables he memorized. These findings led him to conclude that the lion’s share of forgetfulness takes place soon after learning and that the pace later becomes slower. This was an empirical finding that served as evidential infrastructure for the memory-fading curve he later developed.[26]

  A reservation regarding Ebbinghaus’s fascinating findings is that by choosing to focus on meaningless syllables as the object of memory, he actually neglected important essential qualities of memory, such as emotional charging (which is absent in the case of emotionally neutral syllables) and personal meaning. These are two fundamental measures that greatly deepen the traces of memory in our brain.

  When we study “transparent” information that is not colored in the colors of emotions or personal meaning, the result is likely to be similar to the one reported by Ebbinghaus.

  Ebbinghaus published his findings in 1885 in a 123-page-long book called Memory: A Contribution to Experimental Psychology, which became a constitutive classic in memory research. Following the discovery of his findings, he coined the term “the forgetting curve” to represent the finding, according to which the main part of forgetting takes place in proximity to learning and its pace becomes slower afterward. The validity of his conclusion was also confirmed in temporary studies.

  It seems that, although forgetting among all of us follows the general rules discovered by Ebbinghaus, the fading pace of specific memories depends on individual factors, the most important of which are the memory’s emotional charging, its relevance to contemporary circumstances, the level of personal involvement in the experience, and so on.

  Some of the methods used to slow down the pace of fading are constant memorizing of the information, or coloring the information with the paintbrush of emotions in order to make it more “rememberable.”

  Another great contribution from Ebbinghaus’s studies is the identification of the “spacing effect”—using specific time intervals when memorizing results in deeper traces in memory.

  Ebbinghaus’s studies show that there is a window of time in which repetitiv
e memorizing of information yields “maximal memory dividend.” The type of information we wish to remember is an essential factor in drawing the borders of this window of time.

  There is computer software that operates according to the “spacing effect” and calculates for us the best time intervals to memorize information. One might claim that letting a machine supervise this component of our spiritual life should not be perceived as lifting the burden of thinking off the shoulders of our brain but, rather, an intelligent use of the silicon brain for the sake of improving the performance of the protoplasm brain.

  Despite the impressive empirical proofs of Ebbinghaus and his followers, it seems that the “spacing effect” has yet to reach its appropriate status as a central insight related to the human learning process.

  It seems that we still have not used the full potential of these insights as a tool to accelerate the learning curve and redesign learning methods.

  Gone with the Wind—How Do Memories Fade Away?

  The locks of memory become rusty as time goes by and are more difficult to open.

  Or, alternatively, the candle wick of memory usually becomes shorter as time goes by.

  A well-known joke describes two very old men who sit on a bench in the park. An attractive woman passes by. One of the old men asks his friend, “Where are the days we used to chase those? Remember?”—“Yes, I remember we chased them,” says the friend, “but I don’t remember why.”

  Many of us believe that a future of forgetting awaits us all and that, ultimately, the lights of memory will turn off and we will go back to darkness. Whether this is our destiny or not, there is no doubt that the sharp teeth of time blunt our memory.

  The Czech writer Milan Kundera said that there is death within forgetting. In his opinion, the scariest aspect of death is not the loss of the future but, rather, the loss of the past.

  Memory loss of life experiences normally does not occur at once; it is usually formed in a pattern of “graded diminution.” Details become less and less clear and gradually fade away. The levels of resolution decrease, and, as memory is fading away, the picture of experience becomes more granular and less accurate.

  As for episodic memories, which contain our personal life story, when the emotional soundtrack that accompanied the experience becomes blurred, the shades of the memory of the overall experience tend to fade away (as “out of the heart, out of the memory”). From a distance of time, the eyes of memory have difficulty noticing the exact details of the experience. When the emotional melody is played in a minor scale, the voice of personal memory sounds weaker.

  Memory Consolidation

  The consolidation mechanism shows lasting selectivity and continues the sieving process at the time when memory impressions have already started leaving their signs on the slate of permanent memory (long-term memory). The dripping of perception impressions, classified as “small fish,” from the sensorial memory (very-short-term memory), the working memory and the short-term memory into the depths of the ocean of oblivion is possible due to the consolidation mechanism, which continues the sieving process within the memory storage systems. The consolidation mechanism has a “Janus face”—one aspect allows for assimilation of information that survived the phases in which short-term memory becomes long-term memory, and the other aspect channels information that is classified as inappropriate for becoming long-term memory out of the borders of the memory kingdom.

  There is an important distinction between passive forgetting—disappearance of impressions—and active forgetting—repressing perception impressions.

  Selectivity is thus manifested not only in the stage of input and initial encoding, but also in the consolidation stage. The process of forgetting at the consolidation stage takes place through passive forgetting (disappearance of impressions) and active forgetting (repressing perception impressions). The consolidation process is like a refinery that refines memories and preserves their essential core.

  Abstract and general (generic) representations are more resistant to the harms of memory fading compared to concrete memories, which lack personal meaning. In other words, the more the memory represents a more unique piece of information that lacks a personal emotional soundtrack, the more vulnerable and prone to fading it is.

  The frequency of using generic memories, which are naturally connected to mental representations of multiple entities, is higher than the frequency of using concrete memories, which constitute mental representations of single entities.

  The level of resistance of a generic memory to the drifting forces of the process of dementia contradicts the great vulnerability of a memory of a single event that lacks personal shade. Generic memory is the mental representation that shares common patterns between different memories, and these patterns create an interface that serves as an anchor that prevents their drifting toward the waterfalls of oblivion.

  Resistance of Memory Types

  Memory disruptions that occur with different brain injuries constitute a wide scope for inferences regarding processes of memory processing in the brain.

  In the 1880s a French psychologist, Théodule Ribot, discovered an important connection pattern in the complex relations between brain injury and memory. He noticed that when brain injury occurs, the “younger” memories are more likely to be lost and the more senior memories are more likely to be preserved.

  The memories that are more prone to fading away after brain injury are those that were created in proximity of the time of injury and encoded hours, days, weeks or months prior to the injury. The memories that were created a long time prior to the injury are more resistant. This phenomenon takes place as a result of the consolidation process, which implants the memories as time goes by. The more lasting the process is, the deeper the traces of memories are in the material storing bed (anagram). This consolidation process might be seen as an extension of the encoding process.

  In most cases of brain injury, short-term memory is damaged more than is long-term memory. Remembering the name of our third-grade teacher does not guarantee the overall effectiveness of memory.

  After a sharp brain injury (such as head trauma), memories from distant events are more resistant than memories that were formed more recently. It seems that the roots of old memories are more deeply implanted in the soil of our brain, thus explaining their high resistance.

  Invisible Survivor

  In cases of brain function injuries, the unconscious memory shows higher resistance, and its survival chances are higher than those of the conscious memory.

  The procedural memory (which encodes how to perform motor tasks) has better chances of survival even among those who suffer from severe memory disorder reflected in other aspects of memory.

  In this sense, procedural memory is like the memory of the muscles, and factual knowledge is like the memory of the mind. For example, among Alzheimer patients, many times the “memories of the muscles” are preserved as the “memories of the mind” that fade out.

  Following electric shock treatments, which are mainly used for relieving depression symptoms in cases where medications do not help, the “forgetting of the previous” is common. This is a type of lasting forgetting and, at times, permanent forgetting of the previous chain of events that took place prior to treatment.

  A person who suffered from lasting memory loss after electrical shock treatments described meeting himself, as he was, in various places only through external documentation (such as photos, and stories told by acquaintances) and not through guidance of his internal memory.

  The Memory and Me

  Memories are the bricks used for building of the self. The answer to the question “Who am I?” lies, to a great extent, among the volumes in the library of our private memories.

  Memory is the bedding from which our personality sprouts. It provides narrative consistency in time and space, which is necessary for the existence of self-identity.

  In the absence of personal memories, “our story” evapor
ates. We disconnect from the chains of narrative gravity that link us to our past and become “nameless” in the land of memories and in our being, one moment is merged into the next in seamless, nondescript unity.

  The answer of philosopher John Locke to the question “What is the self?” was that the self is a solid succession of memories. My uniqueness as myself derives from the solid succession of memories in my brain.

  As a rearview mirror that allows us to look backward, our memory is like a historian of our journey across planet Earth.

  Personal memories carry latent information in them—information known only to the person who was present at a certain event (or to someone who examines the various aspects of that event in retrospect). For instance, a criminal is familiar with pieces of information from the crime scene, which are known only to him and to those who thoroughly investigate the event. Metaphorically speaking, all our personal memories are latent details known only to our brain or to the brain of people who are close to us or shared the same experiences with us.

  The recollection process has a personal shade.

  The manner of processing personal information means, inter alia, our “personal fingerprint” in the recollection process. For example, different people grant a different level of importance to the various types of input coming from the senses.