We remember only a tiny amount of the things we experience because memory space is limited. So we have to use it economically, storing as little as possible and forgetting as soon as is expedient. Catch a few tips to sharpen your memory.

Something about memory

MEMORY is a biological library that we use at every moment m our life. It is difficult to imagine what life would be like without memory. The meaning of thousands of every day perceptions, the bases for the decisions we make, and the roots of our habits and skills are to be found in our past experiences, which are brought in to the present by memory.

Memory is highly selective. When something gets stored in the memory, it is not recorded in all its finest detail, but rather filed away under a few keywords. When we need to recall something from memory, we extract some of these keywords, and fill in the rest by guesswork. Remembering is, therefore, never exact. It is more like reconstructing an antique pot from a few broken shards rather than replaying an old movie.

Some memories seem so fresh and vivid when we recall them that we may have the impression of reliving the event exactly as it happened, but this is an illusion caused by the power of our imaginative reconstruction. When we compare such recollections with those of others who were in the same place at the same time, we may find that the accounts differ markedly, and the differing versions seem equally vivid to each person.

Memory exists not only in humans and animals but also in some physical objects and machines. Computers, for example, contain devices for storing data for later use. As machines have no imaginary power and emotions, so they remember exactly what we input.

During the 1940s and 1950s when severe epileptic disorders were treated by surgically removing part of the brain, doctors found that electrical stimulation of the hippocampus provoked a flood of memories in their patients. Removal of or damage to the hippocampus made it impossible for patients to learn anything new, and at the same time erased memories of events within the past three years. Only older memories were left intact. This kind of amnesia has proved to be permanent. In short, we can say that the memory brain in primates is the hippocampus.

Hippocampus is not the only organ so intricately controlling our ability to store inputs. Another very important part involved is the thalamus, a structure deep within the brain that receives sensory input from other portions of the nervous system and then transmits this information to the cerebral hemispheres and other parts of the brain. Thalamus along with another partner hypothalamus, which plays a key role in the regulation of the autonomic nervous system and of several forms of motivated behaviour such as eating and aggression, forms the connecting parts of the brain – the diencephalons or “between brain”. It links the middle part of the brain with its front part – the forebrain.

The thalamus is the station that responds to a signal demanding recall of the stored cortical treasure. Well-ramified connections from the thalamus touch almost all the sensory pathways engraved with memories. It is the thalamus that passes on the information to the cortex as to which “action replay” should be switched on. An appropriate neuronal circuit when touched upon makes us rush back through time to recapture an experience of the days gone by. The amygdala, a part of the limbic system, is also involved in the formation of emotional memories. In animals, damage to this structure can produce striking difference in behaviour; for example, a typically docile cat may become uncontrollably violent.

Types of Memory

 

There are two kinds of memory-short-term and long time. Short-term memory holds only 5 to 7 items at a time and lasts for 60 seconds or so. Actually short-term memory can be classified into transient and slightly longer-lasting types. Transient memory is lost within seconds to minutes. An example of this is a brief visual exposure to a number of items for recall and listing. This rapid fading must be taking place at the peripheral apparatus; for instance, in this case at the retina.

The other short-term type of memory that lasts longer from minutes to a few hours is through a reverberating neuronal loop, the neurons of which are excited for a short period. Here the memory is maintained by the close loop of excited neurons rather than any loop of excited neurons rather than any permanent physical or chemical changes in the neurons. This type of reverberating neuronal activity cannot be the basis of long-term memory as it is seen that any drug or anaesthetic inhibiting the neurons can knock off short-term memory, but not the long-term memory. For memories to become more durable, a process called long-term potentiation (LTP) is thought to be important. LTP is the tendency of nerve cells exposed to a rapidly repeated stimulus to respond more strongly long after the intense exposure. This means that for long-term memory some functional changes take place in the neurons.

G.L. Collingride and others found a special set of molecules on die synaptic surface to be involved in LTP. These molecules are receptors, called the N-methyl-D-aspartate (NMDA) receptors. Actually when a neuron is excited by a stimulus, it releases a neurotransmitter, known as glutamate. The electrical signals between nerve cells are altered when the neurotransmitter glutamate is released at the axon terminals of one neuron and picked up by the NMDA receptor on the dendrite of another neuron. This causes the production of proteins called kinases. These enhance the passage of electrical signals by opening up ion-channels in the neuronal walls. At the same time, the dendrite of the neuron receiving the message manufactures a messenger molecule, probably nitric oxide, which flows back to the axon of the first neuron and stimulates further production of glutamate. The NMDA receptor is receptive to glutamate only if enough electrical signals are passing along its dendrite. This mechanism permits preservation of memories for several hours or days. Permanent storage involves the formatting of new synapses in active areas and the withering of those that remain unstimulated. During dreams the experiences that have been waiting in hippocampal memory are edited. Some are converted into permanent stores. The rest are discarded. Remember that the hippocampus has a high content of NMDA receptors confirming its role in memory.

Normally repeated exposure to a particular stimulus ensures long-term memory. But there are events, which even once experienced, can be confined to memory. This happens when such events are of crucial importance to the person concerned. At this juncture, it is relevant to cite two types of memory:

  1. Memory learnt by procedure or skill
  2. Memory that involves conscious attention and recall, for instance, facts. The first is procedural and the second is declarative.

Procedural memory is the repository of such skills as handwriting or driving and involves the cerebellum, a part of the brain concerned with the regulation of basic motor activities, and basal ganglia, several clusters of neurons located atop the brainstem within the two cerebral hemispheres that play a role in memory and emotions and coordinating movement. Declarative memory consists of information an address, roads to destination, words, faces and other knowledge thought to be stored in the cerebral cortex, the outer covering of the cerebral hemispheres.

Emotions and Memory

Emotions play an important part in memory. Emotions help to etch events more deeply in our memories. Any event that produces a strong emotion in us, whether negative or positive is recalled more easily and more accurately than an emotionally neutral event. Freud thought that memories of negatively charged emotional events would be “repressed” and therefore harder to recall, but in fact precisely die opposite is the case: Traumatic memories do not retreat in to some dark recess of the mind, as Freud supposed. Rather, they obtrude persistently into consciousness, perturbing us when we would rather forget them, even disrupting our dream. In severe cases, this is known as ‘Post-traumatic stress disorder’, a syndrome characterized by vivid flash back in which the person relives the event in painful detail.

Mood vs. Memory

The ease and accuracy of recall are also influenced by the mood we are in when remembering something. Dozens of experiments conducted by psychologist Gordon Bower show that when we are in a happy mood, we tend to recall pleasant events more easily and more accurately than unpleasant ones. The opposite is true when we are in a sad mood. This phenomenon is known as “mood-congruent recall”.

In one experiment, Bower asked people to recall incidents of any kind from their childhood, and to describe each one. The next day, when the same people were in a neutral mood, he asked them to label each incident as pleasant unpleasant or neutral. The following day, a happy or a sad emotion was artificially induced in each person by means of hypnotic suggestion and they were then asked to recall as many of the incidents as they could. Bower found that those in a good mood remembered many of the incidents they had labeled as pleasant, but few of those they labeled as unpleasant. Those in a bad mood, on the other hand, remembered more of the unpleasant incidents.

Improving the Memory

There is no magical formula available yet for making everyone a wizard of memory. Indeed, one of the most important requirements for learning is to pay attention. However, there are some techniques and tips that can improve your memory when dealing with important matters in daily life.

The Romans made use of a system that gave them a reliable key for recalling stored information. This was the so-called Loci Method, an association technique that has proved itself to this day. The Loci method is based on the illogical linking of pictures and chains of association. It is especially useful when a list of different things has to be dealt with in a certain sequence. As indicated by the word Loci (from the Latin locus as place), this links the points of a list with places or locations.

The World Memory Championships, set up by learning and memory expert Tony Buzan and British Chess Grand Master Raymond Keene have been held annually in London since 1991. Dominic O’ Brien, the British world memory champion, “has been unbeatable for several years. In the course of the competitions, he was able to memorise a sequence of 1,140 numbers in the correct order. Dominic O’ Brien makes use of the Loci method to remember numbers. Another method for improving memory is chaining. In this process, large information is converted into a small piece of information. For example, the number 4934685 may look imposing, but 493 46 85 is easier to process. Those who enjoy calculating can also look for hidden equations. For instance, the sequence 369872, can remembered more easily if we think of the following equation: 3+ 6 = 9x 8 = 72.

Certain methods of organizing information as it is learned can make it easier to retain and retrieve. These tricks are sometimes called mnemonic devices. For example, students often try to remember a sentence (“Some people have curly brown hair turns permanently black”) for memorizing a trigonometry sequence (Sin 0 = p/h, Cos9 = b/h, tan6 = p/b). Interference is a major cause of forgetting and in general the more similar materials are, the more likely they are to produce interference. In practical terms, this means that you should arrange you’re studying so that you don’t study similar subjects, one subject that are unrelated; the result may be less interference between them and, potentially, better grades.

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