This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.
2002 Third Paper
If someone asks me, "Where were you on September 11, 2001?" I would be able to give that person an accurate answer. It seems impossible to ever forget the events of that day. How could one forget such a traumatic day? It seems like life changing events would stay with a person forever. However, there are many victims of, let's say, child abuse that cannot remember the actual abuse. The memories of such horrors have been erased so there is no recollection of the events. Being a skeptic, I am not sure if I would be able to forget such horrific events. Repressed memories can also be recovered, through therapeutic treatment. It seems odd how people can forget certain traumas, but still able to remember others. How does memory actually work, and how can one selectively repress certain memories?
Memory and the I-function seem to be closely related. Memory allows individuals to store and retrieve information gained from previous experience. It can then be used to predict human response to certain stimuli. Optic neurons often "make things up as it goes along". The I-function relies on memory in order to do this. Memory is used to perform tasks such as comprehension and production of language, reasoning, and recognition of declarative. Memory is also necessary for skill acquisition. Different models of memory have been proposed. One is that there is a limited capacity for the amount of information that can be stored. Memory can decay, and the longer a memory has been stored and not used, the less available it will be. As new information enters the memory, it may be harder to access other information and cognitive system seems to be less efficient (2).
Memory consists of three basic functions: encoding, storage, and retrieval. Encoding is the actual formation of memory. It is an active process which screens out certain materials, and allowing only selective material to be encoded. It is thought that all materials are registered, but only certain ones are retained in memory (3). The more distracting and useless messages are screened out. The encoding of the memory can be affected by how much attention is devoted to the message. Encoding can be done at three different levels. The first is the structural level of encoding, which focuses most on the physical characteristics and structures. This is the shallowest level of encoding. The second is phonetic encoding, which focuses more on words and the sounds of words. The third, and deepest level, is semantic encoding, which emphasizes the meaning of the message. Encoding works in association with other processes. It is part of elaboration, or associating the message with other information. It also works with vision and visual stimuli. Visual images can add more depth on what is being remembered. Memory is also self-referent, which allows the individual to decide how the material is relevant to his or her life. This message that has been encoded is called an engram, which will lie dormant until it is retrieved (4).
After the memory is formed, it must be retained and stored. There are three stages to memory storage: sensory storage, short-term storage, and long-term storage. Sensory storage is allows the individual to store the sensory image for a short duration of time, a couple of seconds, just enough time to gain perception of the image. Short-term memory can last for about 20-30 seconds, without rehearsal of the information, for example, remembering a phone number after looking at it. It is a working memory as long as the rehearsal of the information is continued, and the short term memory can be maintained. There is limited amount of storage space for short-term memory, and to increase capacity, information can be blended together. Short-term memory can be lost by simple decay and displacement. Long-term memory is thought to be permanent. Long term memories are not forgotten; only the mode of retrieval is lost. This can be seen with flashbulb memories, when a vivid recollection of a certain event can be remembered. It is also seen with hypnotic aided, or recovery of memory, when a certain memory can be unearthed with the aid of therapy. However, because the memories are never 100% accurate, it is possible that long-term memory is in fact not permanent. Information from the short-term memory can be shifted into long-term memory. This can be done with repetitive rehearsal of the information or with the significance of the information that is being rehearsed. If the information is important enough, it can shift from short-term to long-term memory (4).
Once memories are stored, they need to be retrieved at appropriate times. Memory retrieval is a process that relies on the cues and stimuli from the environment. Usually it is helpful for the individual to be in the same context as he or she was when the memory was formed in order to retrieve it. The original mood that the individual was in may also help in retrieval of the memory. Sometimes memory retrieval may be inaccurate because the memories can be misconstrued in the mind (1).
The physiological mechanisms of memory are still being discovered. It is thought that the memory process depends on "synaptic tagging" or "late heterosynaptic reinforcement", which describes the interaction between synaptic inputs to a neuron. When the brain forms a memory, it is strengthening the neurons that participate when encoding for the memory. The different changes at the synapse and their interaction with the neurotransmitters account for different memories. Patients with Alzheimer's disease are shown to have a depletion of the neurotransmitters acetylcholine and glutamate (5). When a person forgets something, the connection between the neuronal networks has been lost (4).
Memory can also depend on the coordinated expression and the specific regulation of certain genes. Different genes encode for different proteins. The encoding of the different proteins is important for the formation, modulation, and plasticity of the synapse. The connection between genetics and memory is still not completely understood, and research is being done for better understanding (5).
Memory is a very complex mechanism, which is not always accurate. That is why it is difficult to rely on the words of different eye witnesses of the same crime. Usually, each different witness remembers something different. The mind is capable of repressing memory as well. The mind is able to subconsciously forget a certain event, usually traumatic events, as a defense mechanism. These repressed memories can be recovered; however, there is much controversy behind that. Many argue that recovered memories are not always accurate (1).
Memory repression is done through a dissociation process. The dissociation process is an active process which causes the conscious and subconscious to split in the active experience. The active experience is like the I-function, it is the neural structure that operates all internal and external sensory inputs, and regulates behavior, learned processes, and memory. Dissociation can be done both automatically and voluntarily. One can automatically repress noise or sound. For example, when one is reading and concentrating, he or she is able to not hear the noise in the background. One can also voluntarily repress a thought or memory. One can avoid thinking about a certain memory or message. It is still in the memory, but the dissociation process keeps it from going into the consciousness, and remains in the subconscious (7).
The memories that are repressed can be recovered, though there is much controversy in that. This is because many patients who go through repressed memory therapy also end up with False Memory Syndrome. This is when the patient remembers something that did not even happen. A false image is planted into the mind, and is accepted as truth. However, there are positive results of repressed memory therapy. It allows the person to recover and face the pressed memories, whatever they may be. This is believed that it is the only way a healthy psychological state can be obtained (6).
Repressed memory therapy can be done using different techniques, some in combination with others. These techniques include hypnosis, group therapy, visualization, dream work, and suggestion by the therapist. These techniques help patients remember the traumatic events. One of the controversial issues with repressed memory therapy is concluding that any abuse has in fact been done. It is the therapist who decides whether any abuse, or other traumatic events, has actually occurred, and their decisions are not always accurate. This is how false memories are planted. All the techniques listed above essentially put the patient back to the time of when the abuse happens, or when the therapist believed that is happened, and allows the patient to relive the trauma (6).
The reliability of the recovered memory is still uncertain. Sometimes, the patient may combine pieces of dreams and reality together to fabricate an image is accepted as a truth. Often, in group therapy, patients experience communal reinforcement of delusion. People in groups often encourage the fabrication of outrageous stories. Groups nourish the birth of fantasies that are farfetched. Therapists also encourage patients to talk extensively about their childhood, background, etc to try to make conclusions of abuse. Patients are often praised for it, and if a patient is hesitant, the therapist may conclude that the patient is in denial, or needs more recovery therapy. Furthermore, some memories are forgotten not because they are repressed, but because either the person was rendered unconscious during the trauma, the brain was damaged due to the trauma, or the person was too young to remember the trauma (6).
As mentioned before, even if memories are repressed, it may not be intentional. Some people choose to deliberately forget some traumatic experience. Memories can be forgotten due to a weak neural connection that was formed during the time of the experience or the brain did not encode for the memory (6). However, it can consciously be forgotten as well. Earlier, it was said that memories are able to decay and replaced. If a person chooses to forget a certain memory, he or she can just stop thinking about it. With time, the memory will fade and be replaced with other memories (2).
The idea of memory repression makes us review the idea of I-function. The I-function is based on experience, good or bad. Some of the actions of the nervous system are based largely on the I-function. So when someone has repressed memories, does that mean that the I-function is defective, or is there something even higher than the I-function that controls memory? This also makes me think about the control that we have over our thoughts and mind. I would like to think that I have total control of my mind, but the idea of unconsciously repressing memories makes me uneasy. How does the brain know which memories should be repressed? Is repressing more detrimental than actually remembering them? Being able to face traumatic experiences, and move on seems healthier than repressing them. I do not quite fully understand why the brain would repress memories in order to protect the person. The mind is a web of mysteries, and memory repression is just on thread of the web.
3)Mechanim of Memory
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