Memory: store and retrieve it
By Dr Robert M. Youngson
The processes involved in human memory are more complex than they seem, certainly much more complex than those involved in the processing and storage of data on the floppy or hard disk of a computer. Nevertheless, a great deal has been discovered in recent years, and the precise nature of human memory is gradually being uncovered. Research into this area produces conflicting evidence, and there are some differences of opinion among the experts.

Coping with daily stress
Everyone experiences stress at certain times in one’s life, often due to events beyond his control. Whatever the sources of stress in your life, however, you can learn to control its effects on you.

Deja Vu

Memory: store and retrieve it
By Dr Robert M. Youngson

The processes involved in human memory are more complex than they seem, certainly much more complex than those involved in the processing and storage of data on the floppy or hard disk of a computer. Nevertheless, a great deal has been discovered in recent years, and the precise nature of human memory is gradually being uncovered. Research into this area produces conflicting evidence, and there are some differences of opinion among the experts.

Aristotle (384-322 BC) came to the conclusion that memory was situated in the heart, not the brain, and his ideas held sway for about 500 years until overturned by Galen (BC. AD 130-201), whose anatomical dissections indicated that the brain was a much more likely candidate. Medieval ideas of memory were, as today, based on analogies with the technology of the time. Then, the most advanced technology was hydraulic, and memory was conceived as a flow of fluid through pipes, controlled by valves. Rene Descartes (1596-1650) also subscribed to a hydraulic analogy, the fluid being "animal spirits". Descartes believed that when we wanted to remember something, the pineal gland drove these spirits to different parts of the brain where they encountered physical traces left by the object we wished to remember.

Today, memory is regarded as a function of the brain, and defined as the ability to store and retrieve information. The term "memory" is also used for the actual information store. Unlike the arrangements in a computer, however, human memory is not a discrete and recognisable part of the brain where data can be stored. While it is true that certain known parts of the brain are involved in the temporary storage, registration, processing and recall of information that is to be permanently stored, there is no single part corresponding to a computer's disk drive for long-term store.

The nature of the input

The sensory experience that precedes the storage of data in memory is very complex, suggesting that there may be many different kinds of memory — visual, auditory, olfactory (smell), gustatory (taste) and tactile (touch). Moreover, data is never presented to us in simple form, but always as part of a complex context in which it is embedded. This context is likely to form part of the memory; indeed daily experience shows us how important context and associations are for effective memorising. For example, a single item of information conveyed to us by way of speech will be set in a context of other data — the appearance of the speaker's face, its spatial relationship to other things, the quality of the voice, and the displays of emotion. Research has shown that there is good reason to believe that this information is distributed to those parts of the brain known to be concerned with the different sensory functions.

Short-term memory

Complex perceptions cannot all be stored separately at the very moment that they are perceived, so some kind of analysis and selection is necessary to determine what should be registered and kept. What happens is that only significant changes in familiar contexts are likely to be registered by the brain. Such analysis and selection cannot be performed, however, unless the data is stored temporarily so that it can then be operated upon. This means that there must be two levels of memory store — iconic (short-term) and working (long-term) memory.

Iconic memory has to be constantly refreshed. Most of us can look up and remember a new telephone number if we repeat it to ourselves a few times before dialling. But if we are interrupted the number will be lost as new incoming data displaces the current contents of the short-term memory. There is also a strict limit to the length of any item of new data if it is to be held in this short-term store. Again, most of us can readily hold a seven or eight-digit number in our heads, but a twelve-digit one is too long. Iconic memory can also be emptied by a blow or an electric shock to the head, suggesting that short-term memory operates via some kind of dynamic neuronal circuit, possibly of circulating nerve impulses. A useful analogy is that of the volatile random access memory (RAM) of a computer, the contents of which are lost when the power is turned off.

Mnemonics

Each of us carries in the brain an almost immeasurable amount of data, recorded, somehow, via short-term memory and preserved, often for a lifetime, in permanent storage. Some evidence suggests, however, that stored information need not always pass through the short-term memory, but may go straight into long-term store. This mass of data is highly organised in terms of meaning and association; the better the organisation, the more accessible it is. Clues, mnemonics and, in particular, cues, all speed up the efficacy of information retrieval. For instance, one might forget the beginning of Hamlet's celebrated soliloquy, but the cue, “To be....” is likely to evoke the continuation,'... or not to be”. Similarly, efficient registration for long-term storage demands good organisation and strong association. The scholar with a profound grasp of his or her subject assimilates new information on that subject with the greatest of ease, so long as it can be related to existing stored data. Entirely new matter, unrelated to any previous experience, is much more difficult to memorise.

The interface circuits

We now know the exact sites in the brain through which sensory data must pass to be stored in memory. These interface circuits — through which long-term memory is recorded and recalled — are contained in two large structures on the inner surfaces of the temporal lobes of each cerebral hemisphere — two massive collections of nerve cells known as the amygdala and the hippocampus. Together these make up the limbic system. The amygdala is connected to all the sensory areas of the cortex by two-way pathways. The hippocampus also has extensive connections to these areas. Destruction of these two structures leads to profound loss of memory.

The basis of long-term memory

The exact physical basis of long-term memory remains unknown; several hypotheses have, however, been put forward. The sheer size of the database in relation to the size of the brain implies that the unit of information — whether it be a binary digit (bit) or some other code— must be very small. This has led some scientists to suggest that a protein molecule provides the basis. It would be naive, however, to think of long-term memory storage as based on two kinds of protein molecule corresponding to the presence or absence of a spot of magnetisation on a computer disk. For one thing we have no reason to suppose that the nervous system operates as a computer does on the binary system (i.e coding 1 for "on" and 0 for "off"). For another, the life-time of protein molecules is very much shorter than the length, as far as we know, of human memory.

There is evidence that the sites of memory are the same as the areas of the brain where the corresponding sensory impressions are processed — in various parts of the outer layer (the cortex). It is now almost certain that, in memory recall, the amygdala and the hippocampus engage in a kind of feedback dialogue with the appropriate part of the cerebral cortex — playing back the kind of neurological activity that occurs during sensory experience, rather in the manner envisaged by Descartes.

This being so, it seems likely that long-term memory store takes the form of the interconnection of nerve cells in a particular way. Evidence suggests that particular connections — activation of the nerve-to-nerve junctions known as synapses — occur as a result of repeated mental stimulation of the kind that occurs during sensory experience. Scientists are beginning to understand the way in which repeated stimulation leads to permanent link-up. The addition of a phosphate group (the process of phosphorylation) to a brain protein, called F1, as a result of the action of an enzyme, protein kinase C, is now known to be capable of causing the necessary changes in the synapses. Unfortunately for laboratory studies, though, protein modified in this way has a limited life span, ranging from minutes to weeks. Various ingenious suggestions for ways round this difficulty have been proposed, including processes that automatically regenerate protein molecules and a special form of gene expression that gives rise to long-life protein.

Coping with daily stress

Everyone experiences stress at certain times in one’s life, often due to events beyond his control. Whatever the sources of stress in your life, however, you can learn to control its effects on you.

A number of simple measures, such as meditation or confronting the source of your problems, can be used to ease tension. Learning and carrying out these anti-stress techniques can improve your ability to cope with stressful situations.

Reducing your stress level: Identifying what is causing your stress is the first step to reducing it. Taking almost any action to relieve it will help because this is a sign that you are no longer prepared to endure an unacceptable level of pressure.

Taking control: Organise your time to reduce your stress levels — plan ahead, do not over-schedule yourself, and leave time for relaxation. Make a list of all the things that have been troubling you, putting them in order of priority. Then, beginning with the problem that causes you the greatest irritation, anxiety, or stress, work out a way to solve it or deal with it. As you solve each problem, move down your list, tackling only one source of stress at a time.

Talking through problems: Discussing what is bothering you is often a good way to find a solution. Once you have decided who or what is at the root of your anxiety, talk the issue over, either with a friend or with the person who is causing the problem.

Admitting that you cannot handle a problem alone may be an embarrassing or awkward confession to make, but involving another person in your troubles at an early stage can speed up the process of finding a constructive solution.

Coping with a life crisis: No matter how well planned your life is, or how healthy your mind and body are, a crisis can bring on stress. The following strategies may help:

• Learn to recognise a crisis.
• Seek and listen to advice.
• Do not brood about past events or blame someone else.
• Do not worry over future events that are beyond your control.
• Consider each problem separately.
• Make a list of your worries; they will seem less overwhelming.
• Stick to a daily routine to create a greater sense of security.
• Take your mind off your worries through a leisure activity or exercise.
• Do not try to work out solutions to your problems just before bedtime.
• Consult a doctor or a counsellor before stress builds up to an intolerable level.

Deja Vu

Almost everyone is familiar with the phenomenon of deja vu ("already seen") in which there is a brief but powerful conviction that what is currently taking place has happened to us before. Usually there is a strong sense of familiarity accompanied by a compelling, but mistaken, conviction that one already know what is around the next corner. There is as yet no consensus of opinion on the explanation of this interesting phenomenon.

Deja vu has been claimed as evidence of reincarnation or of the possession of "second sight" or telepathic powers. Freudian psychologists claim that the experience of deja vu has actually happened before but has been repressed.

Another suggestion is that deja vu is the result of data relating to the current perception reaching the memory store a fraction of a second before it reaches consciousness, so that the effect is as if it is being remembered. In support of this idea is the undoubted strength of the experience of deja vu — which is just what one would expect from such a recently registered memory. In this context it is significant that deja vu is a very common manifestation of certain types of brain damage, such as those that cause temporal-lobe epilepsy.

Another possible explanation is based on the hypothesis that memory recall is a process of synthesis, or reconstruction, from the stored items of the different sensation components that made up the experience, each successive episode of recall being the recall, not of the originally stored data, but of the last such synthesis. If the synthesis involved mistakes, omissions or false elaborations we would have a sense of familiarity but would quickly see that the event, as now apparently recalled, never really happened.

From Bapu’s Ashram to hapless slums

Dr M.L. Kataria, the living legend who writes often for Health Tribune on issues related to the health-care of the poorest of the poor, met Mahatma Gandhi during his short internship at the Sheogaon Ashram not far from Wardha.

National leaders like Jawaharlal Nehru used to visit Sheogaon, a cluster of mud huts, unmindful of dirt and dust. Was it a place of pilgrimage for them? Yes!

One day the young Kataria summoned enough courage and asked Bapu: "Why have you chosen this roadless and obscure village as your place of work?" The Mahatma replied: "Because this is the real but neglected India which we need to build as a strong base...."

Dr Kataria has continued Gandhi's work in numerous slums of India. He lives in Chandigarh with his compassionate wife, a former Professor at Delhi's Lady Hardinge Medical College.

Dr Kataria was honoured with the prestigious Dr B.C. Roy National Award (for Socio-Medical Relief) by President K.R. Narayanan last week.

We reproduce part of the citation presented on the occasion at Rashtrapati Bhavan and wish the tireless man, who has created saints of slums out of ordinary men and women, a long life filled with work, work, and work!

The Citation

Dr (Brig) M.L. Kataria is a medical graduate with four postgraduations from various universities in diverse medical disciplines, three master's degrees in arts, law and business management, a doctorate in administration and organisation, and a post-doctorate in hospital administration in India. During his service in the Armed Forces he also did 12 professional, command, staff and administrative courses at various prestigious defence training institutions. During the decade (ending in 1999) he actively participated in 18 international, national, regional and medical conferences and updates.

He had a long innings of over 33 years in the Armed Forces in various professional, command, staff and administrative appointments in India and abroad, during peace and war, including World War II, the Indo-Pak wars of 1947, 1965 and 1971, and the Sino-Indian war of 1962. He is the recipient of 10 medals for meritorious service in the Armed Forces.

He had a stint of service for a decade at the Postgraduate Institute of Medical Education and Research at Chandigarh and at Rohtak (Haryana). He is also on the teaching faculty of Bharatiya Vidya Bhavan's College of Communication and Management.

After retirement from formal service in 1982, he continues to be in "active service". A persuasive and extraordinary fund-raiser, organiser and administrator, he has established, and is personally operating as an honorary consultant, a chain of nine charitable health-care centres, in urban Chandigarh, in rural and slum areas, and in the adjoining states of Punjab and Haryana. He works for all the seven days of the week, including Sundays, and has provided medical relief to over six lakh patients, at an average of 100 patients a day, during the last two decades.

Besides his mobile door-delivery health-care in six of these nine centres, he has established fixed-at-site free X-ray, laboratory, ECG and dispensary services.

He has been honoured by several organisations and institutions and is the recipient of Republic Day State Award (1996) for socio-medical relief.

He is also a pioneer in health-care for senior citizens. By virtue of his selfless socio-medical relief during the last two decades in urban, rural and slum areas, he has become a household name, a living legend and a dynamic institution...." (KPS)