Friday, January 12, 2007

Fond of Forgetting

A man accidentally trips on the staircase and around 10 nails pierce into his brain. The nails have to be removed at the same angle as which they entered his brain. In spite of such a mishap, this guy still survives and is quite conscious of what’s going on around. Amazing skull we have got that guards us from such gory accidents.

Our brain is the most intricate and complex structure in the universe. The cerebral cortex is the brain’s outer layer and it is often said that we are physiologically different from animals by our relatively heavier cortex. As primates evolved and brains began to grow larger, the cortex expanded and its surface area swelled. To fit into the confines of the brain, it folded up and the folded pattern grew wrinkly with time and ultimately we have a walnut-shaped brain.

This process is called encephalization: the growth of brain through evolutionary time and encephalization is typically defined as “the amount of brain mass exceeding that related to an animal's total body mass.”

It looks ridiculous that there’s so much more to my brain that I’m completely ignorant of.

Now, back to the nail-pierced patient. When he is MRI scanned, it is discovered that he has a tumor in his hypothalamus: one of the supposed areas in the brain where our memory and certain facets of our personality reside. He has two options: either to get the tumor surgically removed and live for 5 years; or stay with the tumor, reduce its impact through radiation therapy and live for 10 years.

If he opts for surgery, he will have his hypothalamus functioning for 5 years but after that, he will lose the benefits of having the hypothalamus.

If he opts for therapy, he will gradually loose memory, self-awareness but will live longer.

The patient and his wife opt for the therapy. Because the wife strongly feels that though she may loose him moment-by-moment, she will be with him longer and as his other half, she can embrace this phase of her hubby’s life too. Sadly, the patient was recently gifted a digicam by his wife. The use of camera after they knew about their plight (as the patient as well as the caretaker) is a symbolic sign of how to store memories and recall them when needed.


Memory is so important to us that we curse our brains when we forget something. I think Jews and Hindus have an unusual concern about memory. The Vedas are not written scriptures but have been transmitted from generation to generation verbally with acoustic articulation. Though the Jews have written scriptures, they emphasize the importance of recalling the scriptures rather than referring to them. For them, remembering is a religious imperative. Judaism stresses on the sacredness of human life and Jews are required to memorize their holy book, the Torah (Hebrew for direction). In Hebrew, the word to remember is Zakhor, which very well stretched to mean that to remember is to act (darhar). Memory is not just a vague recollection of past but action is embedded in every memory recall. That’s been a principal reason why Jews were a religion that became people rather than people becoming religion.


Memory is so important to us and yet, one cannot explicitly localize a single superpower of memory in our brain. A world-famous neuroscientific case was that of Harold, a young man who was operated for epileptic fits - due to which large portions on either sides of the brain were removed. As a result, Harold was terribly stripped off his capability to form new memories. Though this loss can be due to the loss of the key brain regions, it was later found that memory is organized in different ways and various regions in the brain are assigned as the storehouses of different kinds of memory.

Memory is usually of two kinds: short-term memory and long-term memory. Short-term memories deal with our immediate recollection of experiences that recently happened like being attentive while trying to listen to the phone-number and jotting it down. Long-term memory helps us out in our overarching functions of memorizing the past and important ideas. This memory is divided into episodic and factual memories. Episodic memory helps recall the events that have happened in a certain location at a specific time. Factual memory helps recall facts and ideas relating to persons and places, words and things.

The location of this variety of memories can greatly vary but one can tentatively locate their store. Human brain is broadly and regionally differentiated, and brain imaging studies certainly show specific areas of the brain that light up when specific mental functions are in process. However, the relation between the areas and their designated functions seems complex. There is, for example, no “memory bank” mimicking a computer’s memory.

Damage to the hippocampus interferes with the ability to retain new long-term memories, but those memories are not encoded by specific neuronal connections. Over time, other brain regions and connections become involved in specific memories.

There is no process of build-up and slow loss of fixed wiring connections of neurons in the brains that correspond to mental states. Certainly, new neurons and synaptic connections are being produced and are dying throughout life with, alas, a preponderance of losses as we grow older. But these births and deaths are not in some one-to-one connection with events remembered or individual mental processes. There is hardly any fixed physical module corresponding to the ability to do long division or remembering Pi to six decimal spaces.

Just as new neurons become physically involved in old functions and memories, neurons that are already present can increase the number of connections to other neurons over time, and thus become involved in new multiplicity of pathways. We don’t have neuron-by-neuron catalogs that relate particular cells to particular mental states, so it may well be that such multiple pathways are not related in any categorization that makes logical sense. Nobody really knows how neurons exactly manage their astonishing complexity of connections.

Consider two simple case-studies. Oxford zoologist John Krebs worked on a species of birds called Marsh Tits that store food in a special hiding place. Storing of food is an event; so there is episodic memory involved here. Then, one group of birds were allowed to take the fed food back to their hideouts; whereas another group of Marsh Tits was given food that couldn’t be taken back. After some time, it was found that the first-group birds’ hippocampuses were enlarged.

Our brain is meant to adapt to its needs (just as the birds adapted to theirs) and this we acquire through direct confrontation with the outside reality which is mapped with the inner tools to encode the grasped reality. Without the experience that has a lot of emotional significance enfolded into it, brains remain in their primeval stages of resistance to growth. Even the hippocampus stores memory for a short duration (say a year or two) and then transfer it to the cortex for permanent storage.

Yet, to think that hippocampus and cortex are elite centers of memory storage is fatal. An accidental penetration of a foil through the nostrils into the brain of a radio technician damaged a portion above his brain stem called thalamus. Though he lost his memory of the past two years, he consequently could recollect the lost memories and this proves that the thalamus is also responsible for memories as well as learning to memorize.


The eminent neurobiologist, Steven Rose (b.1953), found that when long-term memories are recalled, it is not the original memory of the event that is referenced but the recent recall of it. So, we have “memories of memories.” This idea perfectly aligns with the French philosopher Paul Ricoeur’s (1913-2005) notion of memory and forgetting. One has to forget to give way for new memories to be formed and to transform the brain. Heidegger’s saying that “memory is the foregathering of thought” is innocuously used by Ricoeur –while discussing historical knowledge– to understand the past in the present through the accessible “traces of the past.” The past has two facets: the individual’s memory that animates the present (the part); the collective memory that provides a backdrop for individual memories to take shape.

This collective memory is endorsed by the “testimonies” gathered by the individual memories. Ricoeur doesn’t wish to prioritize one memory over the other but one memory “feeds” into another. So, historical accounts are “interpretative” in nature having “a character of likelihood or credibility rather than certainty.” Further, memory is bound to be forgotten – everything of the past cannot be completely recalled in the present. So, testimony gives “credence to the historical representation of the past.”


Memory is largely connected with consciousness. We just don’t lose memory but a good part of consciousness with it. Memory loss significantly alters this continuity and can cancel it any moment. Some have tried to view this aspect as related and solvable by the tempting metaphor of computer. Memory deficits cannot be compared and mimicked by computers to evolve roads to recovery. Computers have a stored memory space that can be used and reused whenever required. But, there is no evidence of specific memory traces stored in the brain in a similar manner. Steven Rose has been at the forefront of memory research using chicks to understand the spread of associations in brain made by one’s memory. These chicks peck at objects that fall within the vicinity of their vision. If one dips a chrome bead in a bitter-tasting liquid, then these chicks avoided such beads. This was not because they remember such beads, but due to the ways in which various parts of the chick’s brain processed the size, shape and color of the bead to indicate in an integrated manner the distaste of the bead. Memories are therefore so deeply embedded and extended in the brain that no one single place is there where the complete association is achieved.


The great Canadian neurosurgeon, Wilder Penfield (1891-1976), who performed numerous surgeries on epileptic patients, had a lifelong pursuit of how to account for the mental states that caused the brain states. Is mind in the brain or are the two inelegantly separated? Initially, he performed surgeries on epileptics by identifying the damaged portion of the brain’s temporal lobe (a brain’s area beside the ears) through touching electrodes on various parts. What makes these surgeries interesting is that while locating the brain tissue that is causing epilepsy and excising it, Penfield discovered that patients develop a “double consciousness”.

This means that while the patients indicate and explore the epilepsy-causing tissue when Penfield touches their brains with electrodes, they are conscious of two realms. One immediate and other past, and both could be vividly and elegantly described. The immediate environment is the operation theatre, the surgeons and their scalpels, their toolkit and tables, etc; the past was also vividly recollected and described exactly as it happened. There was negligible difference between the patient’s recollection of the event and the event’s actual occurrence. Or in neuroscientific terms, the patient has an exact blueprint of an event’s episodic memory in his working memory.

Double consciousness double-crosses to point to another aspect of the brain. A seductive metaphor for the brain is that it functions like a computer as both brains and computers seem to be mechanically programmed whose code can be swiftly deciphered as well as encoded. Yet, double consciousness is an improbable feat of human mind that enhances the possibilities of the brain. Brain is not a rigid 1.3kg jelly whose majestic functions can be permanently replicated. It is so dynamic that it adapts itself to the needs of the body; its fluidity and density are not easily grasped and reformatted into a computer simulation. A computer can nevertheless have a vast memory that can be used for massive retrieval. But, a computer is not so dynamic as to adapt itself to changing conditions of memory storage and hence, smart retrieval doesn’t transform into sane recovery of information.

Memory teasers are common to many neurological patients. The great Soviet neuropsychologist, Alexander Luria (1902-1977) narrates -in The Mind of a Mnemonist- about the extraordinary vast memory of his journalist-patient, S. Mr. S couldn’t forget anything; every thing perceived by him had a retrievable place in his memory. He could remember people not by their faces but astonishingly by voices and sometimes, even color. A person was recalled as a sharp red individual for him. Places were visually mirrored in his memory and he could remember the objects -in say a room-by navigating through the visualized mirrored spaces. Though this is a rare kind of memorizing, the mnemonic techniques used by S were quite impressive.

Memorizing therefore is not a single static act but a dynamic cognitive drama

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