Moments we'll never forget

While everyone can vividly recall landmark events, no one is immune from the occasional lapse.

The recent anniversary of the death of Sheikh Zayed bin Sultan Al Nahyan will have evoked an array of emotions and memories redolent of his reign as the Ruler of Abu Dhabi and President of the United Arab Emirates. Most people who lived in the UAE at the time will also be able to recall with some clarity the date and time, where they were, who they were with and what they were doing when they heard of his passing.

Such recollections are examples of 'flashbulb memories' - these are long lasting and highly vivid memories of important and dramatic events. These events are captured as if a photograph had been taken at the very moment that the event occurred and as such they become ingrained indelibly in our memories. Other examples of these types of memories may relate to personal and happy events in our lives, such as the birth of our children, weddings or other major life celebrations as well as traumatic events such as being involved in an accident or undergoing major surgery.

Our memory system plays a vital part in defining who we are and without it we would be like newborn babies - unable to recognise anyone or anything as familiar and unable to talk, walk, read and write because we wouldn't remember anything about our language or culture. Long term memory is the function that enables us to store such information so that learning can occur. It is believed that the capacity of the brain is unlimited for both the number of memories that we have and how long we will retain them. In comparison to the memory available in computers our brains have an enormous storage capability. We have a huge amount of information stored in our memory - we are able to recall our childhood, the names of all the people we know, travel routes, describe places we have been to, the types of food we like to eat, experiences that we have had and emotions and sensations that we have felt; we can recall the books that we have read, the exhibitions we have seen and the tasks we have undertaken in our working and everyday lives. However, allied to remembering is forgetting, and while a great deal of research has concentrated on the ability of the brain to retrieve information from a short term memory store, less information is known about how our long term memories erode. This is because as we get older there is a general decline in our basic cognitive function which consequently impairs memory function and these lapses in memory generally become more marked with increasing age.

While fading memory is associated with older age or degenerative diseases such as Alzheimer's, we are all prone to memory failure at some time or another. For example, have you ever found yourself going into a room or gazing in a cupboard or opening the refrigerator door and wondering what it was you were either doing there or looking for? Have you ever searched high and low because you couldn't recall where you had placed your car keys or reading glasses?

These momentary failures in our memory systems are linked to what is known as prospective memory (PM) and is an important aspect of day-to-day memory function. PM is the process of remembering to do things at some future point in time. Examples of PM include remembering to pick up items you needed when shopping, making an important telephone call or carrying out a task such as remembering to pay a utility bill on time. Research in cognitive psychology has demonstrated that while retrospective or long-term memory recall can be facilitated by external prompts or cues (such as friends jogging our memories or writing ourselves lists of things to do), PM relies much more on internal prompts and cues (such as our own internal dialogue or using mental pictures) to facilitate recall.

Our memory system can also be prone to interference from other physical processes such as experiencing stress and feeling pain. When we are stressed or placed in a stressful situation our bodies release cortisol: a corticosteroid hormone or glucocorticoid. Chronic exposure to high cortisol levels has been proposed to be predictive of memory deficits. Empirical support for the link between stress-related cortisol levels and memory impairment has been reported, and this impact on memory has also been found in people who are prescribed glucocorticoids (often to manage allergies). Long term use of these medications as well as unrelenting and unmanaged stress can therefore impinge on our memory systems. The stress response also cascades when we experience pain and so cognitive functioning and particularly our memory function can be impaired especially when the pain is chronic in nature. This is because high levels of glucocorticoids can interfere with the chemical processes involved when we either learn something new or commit something to memory - a major mechanism known as long term potentiation (LTP).

LTP occurs within the major processing pathways of the hippocampus, which is part of the forebrain and belongs to the limbic system. LTP is limited to those synapses (a synapse is the process by which our neutrons or nerve cells communicate with other nerve cells) that are activated together and requires simultaneous firing in both neutrons for a memory trace to be formed. These cells use glutamate which is the dominant neurotransmitter in the brain to facilitate communication with other neutrons. The chemical sequence involved (including sodium, potassium, magnesium and calcium) ultimately impacts on the likelihood that LTP will occur. An influx of calcium ions can initiate LTP, the blocking of the calcium channel by magnesium ions inhibits LTP and the maintenance of LTP occurs through a circular increase in the release of the neurotransmitter glutamate. Therefore, the presence of other chemicals (whether induced by the stress response or via prescribed medication) can have a deleterious impact on memory formation in a number of ways.

In order to bolster memory function it may therefore be beneficial to undertake an appraisal of the amount of stress in our lives and through stress management measures reduce or limit the impact that the stress has on our bodily systems. Additionally, techniques for memory improvement include completing jigsaws and memory puzzles that can be used to facilitate cognitive and memory functioning and serve to give our brain a workout. Other methods that facilitate learning and aid recall involve the use of mnemonics.

Common mnemonics are often special words or phrases that help the person remember something else (often lists of words or facts). For example, in mathematics, the mnemonic BEDMAS serves to facilitate the recall of the sequential mathematical actions that must be undertaken when there are multiple operations within the calculation (Brackets, Exponents, Division, Multiplication, Addition, Subtraction). Mnemonics are popular memory aids and can be used in countless ways to help with learning.

For the majority of us however, lapses in our memory function remain just that, lapses. With the forthcoming National Day celebrations shortly upon us it seems fitting then to end by remembering the founding father of the federation and the legacy of his time as Ruler of Abu Dhabi and President of the United Arab Emirates. While enjoying the holiday period recall the many achievements of his reign and hopefully consign to your memory many more 'flashbulb' moments or pleasurable experiences.

Carol Campbell as an assistant professor of natural science and public health at Zayed University in Abu Dhabi