Amnesia is the loss of memory due to various factors that affect the healthy cognitive functioning of the brain. The study of amnesia is essential to the understanding of the brain functioning and the different parts of the brain that control memory. This paper provides detailed research into amnesia starting with the history of amnesia, which can be traced back to a patient named Henry Molaison. It also shows the normal cognitive functioning of the brain, a condition in which it can process information quickly and stores both short-term and long-term memory. The study provides a more in-depth insight into the disease by explaining the two types of amnesia. The first is anterograde amnesia a situation in which the brain cannot form new memories. Retrograde amnesia is a condition in which the brain loses its normal ability to retrieve information about events that happened before the onset of amnesia. The paper outlines the various causes of amnesia. They include traumatic brain injury, hypoxic ischemia, intracranial surgery that is the surgical process of treating temporary lobe epilepsy and cancer, which damages the hippocampus. Stress is also explained as a causative factor in the development of amnesia. The study provides current research in which amnesia can be caused by biological forces and not through detectable brain damage through the process of dissociation. The paper proposes a new area of study, which is the effect of approaches of preventing amnesia.
Amnesia refers to a condition of memory loss where an individual is unable to remember information that is stored in the brain. (Wingfield and Cronin-Golomb, 2003). It may be caused by a variety of factors such as brain damage due to trauma, stroke, and alcohol and drug abuse. Amnesia should not be confused with situation when one is a little forgetful for instance when one has taken a lot of alcohol. It is a severe loss of many memory, which should not be the case under normal cognitive brain functioning. Individuals with amnesia cannot remember milestones and events in their life no matter how memorable they are (Wingfield and Cronin-Golomb, 2003). It is a rare condition in reality despite its constant revelation in many books and movies. Some Amnesia conditions are reversible while some are not. The severity of the disease depends on which part of the brain is affected or damaged, and it can affect anyone with no consideration for age or gender.
The History of Amnesia
The concept of Amnesia is complex like that of cancer because there are many underlying factors that cause the condition. The different factors lead to different types of effects on the brain which lead to the development of amnesia. However, the history of Amnesia can be traced back to a patient by the name of Henry Molaison. He was the first patient to develop amnesia. He got involved in a bicycle accident at the age of seven years and developed seizures (Squire, 2009). Although he was put under medication, the medication was not able to control his seizures. Between the age of seven and nine, he experienced minor uncontrollable seizures, which progressed to major seizures after the age of sixteen. For many years, he suffered the seizures, and at times they were so severe that he could not go on with his job. He agreed to have the physicians to carry out brain surgery on him to remove a suspected part of his brain to try and prevent the seizures which were affecting his mind.
What was first considered a minor injury led to the discovery of amnesia, and insightful revelation on how brain functions of memory are related to the various parts of the brain. His hippocampus was removed to control the seizures. The surgery was successful as the seizures were controlled, but after the surgery, he was left with amnesia. The patient could not remember some information before the operation such as events from his childhood, his parents, and other events that happened before the surgery (Squire, 2009). He also could not form new memories. If he met someone and the individual left the room, he would forget the encounter within minutes. He could not remember meeting the person. When he was given words to memorize, he would forget the words within minutes.
He could not recall any words after he stopped memorizing and this showed that short-term and long-term memory are different processes. Although he could not recall events that happened before his surgery, he could learn new things but immediately forget. He would improve in learning new tasks after practicing repeatedly. The physicians did a fourteen years follow-up on the patient to learn more about the amnesia. After 14 years, the patient could still not remember any details that happened since the surgery (Squire, 2009). He could provide details that were taking place at the time but could not recall memories such as those from his childhood. When he died, his brain offered to be used for research into amnesia and how it works.
More studies were done on other patients who had undergone surgery and showed that only those patients who had their hippocampus removed experienced amnesia. The more the hippocampus tissue was removed, the more severe the amnesia was. Amnesia was therefore linked to the hippocampus part of the brain, which is where the recent memory is stored. Over the years, more research has been done and has shown that amnesia develops when the hippocampus and other parts of the brain that are associated with memory are damaged. They are responsible for transforming people`s perceptions and awareness into lasting memories. When they are damaged due to injury or other factors, the result is amnesia since memory is lost.
Normal Cognitive Functioning
Amnesia shows that normal cognitive function is essential for memory. The hippocampus and surrounding brain parts can be damaged by the use of drugs such as alcohol leading to amnesia. When the brain is functioning normally and is in a healthy state, it can process information quickly and store both short-term and long-term memory. Injury to the brain causes it to lose its ability to process and store information effectively leading to amnesia (Eichenbaum, 1993). Long-term memory retrieval by the brain requires recovery of information that is not present or is not maintained in an active state by the brain. When the brain is not functioning normally, it is unable to retrieve such information, and therefore there is loss of long-term memory.
Aging people develop memory lapses because their brains are slowly losing their ability to function correctly thus inhibiting the power to recall events that happened a long time ago. This is similar to unhealthy cognitive functioning where the brain loses its ability to recall past information. Normal cognitive functioning is therefore essential to memory because memories are stored in the brain parts such as the hippocampus and when they are not functioning normally, memory lapses kick in and with time develop into amnesia. Short-term memory is processed quickly by the brain when it is functioning normally.
However, when the brain is not functioning correctly, it is unable to process information quickly, and therefore patients with amnesia are unable to recall information they have encountered just some minutes ago. Normal cognitive function is essential to preventing amnesia and memory loss and thus activities that promote healthy functioning of the brain such as playing games, and mental games should be done to ensure the brain remains active and functions regularly. Stress and drugs inhibit the normal and healthy functioning of the brain and can lead to amnesia because they overwork and damage the brain in the long-term.
Forms of Amnesia
Under normal healthy cognitive functioning of the brain, all the events, and experiences of an individual can be recalled. However, with the onset of amnesia resulting from brain damage or other factors, the brain loses its ability to retrieve memories. There are many types of amnesia. One is the anterograde amnesia which is a condition in which the brain cannot form new memories and cannot learn new things (Smith et al., 2013). The brain does not recall immediate events after the development of this amnesia. Under normal cognitive functioning, the brain transfers new information from the short-term memory to the long-term memory, and therefore the brain can retrieve the information even though it is recent. Amnesia prevents the transfer process, and consequently, new information is not stored. The other type is retrograde amnesia in which the brain loses its normal ability to retrieve information about events that happened before the onset of amnesia. Anterograde amnesia occurs more among the population, and it has been found that the two forms can occur together.
Recent information about Amnesia
The recent research studies have shade light to some development in understanding amnesia and the related-factors leading to its existence. One of them is traumatic brain injury leads to the development of amnesia. When the brain is functioning normally, the brain is healthy and can recall information in both the short term and the long-term memory storage. Brain damage affects the normal functioning of the brain leading to the inability of the brain to recall information and hence leads to amnesia. Recent research shows that there is an increase in the reported incidences of traumatic brain injury in the world and the United States in particular. The age of those suffering from amnesia has shifted from the older to the younger population because of traumatic brain injury (García-Castro, 2017). The risk of traumatic brain injury has increased among children below the age of four with falls being the leading cause of the traumatic brain injury. It is challenging to identify the development of amnesia among children because the effect of traumatic brain injury may develop in later stages.
Due to the great number of glutamatergic neurons that form the hippocampus, this structure is especially sensitive to the lack of oxygen, which triggers an excitotoxic cascade that causes neuronal loss (Wroge, Hogins, Eisenman, & Mennerick, 2012). Voxel-based MRI volumetric studies in hypoxic-ischemia AD patients show consistent grey matter atrophy in bilateral hippocampal formation, putamen, ventral nuclei of thalamus, and brainstem, when compared to healthy age-paired individuals (Vargha-Khadem et al., 2003).
Hypoxic ischemia is also a concept that is related to the development of amnesia. Many neurons form the hippocampus. Under healthy cognitive functioning, the neurons transmit information enabling individuals to retrieve both short term and long-term information. The neurons require oxygen to function effectively, and when there is an inadequate supply of oxygen, there is a neural loss. This leads to the ineffective transmission of information which can lead to development of amnesia. Patients who suffer from amnesia have grey matter in the hippocampus.
Cancer is a disease that can cause amnesia in different ways that lead to the deformation of the hippocampus. Cancer causes the growth of abnormal tissues in the brain, which can affect the normal cognitive functioning of the brain. It can change the structure of the hippocampus making it to function improperly. Since it is responsible for memory, hippocampus` damage can cause amnesia. Surgery can be done to remove the abnormal tissues that grow in the brain due to cancer. However, the surgery can damage areas around where the tissues develop leading to damage of the hippocampus, which can also lead to the development of amnesia (García-Castro, 2017). Another way in which cancer causes amnesia is through the effects of radiotherapy and chemotherapy. The two cancer treatment approaches lead to abnormal development of the hippocampus and adversely affect cognitive development and can, therefore, cause amnesia.
Severe stress is another factor that can cause amnesia. It is common knowledge that acute stress is unhealthy for the brain because it inhibits the normal functioning of the parts of the brain. However, there is limited knowledge of how exactly the process happens. Though when the brain experiences acute stress, it initiates a response to deal with the stress. Constant response to the stressful events and experiences can lead to neuron loss, which inhibits the ability of the hippocampus to form and transmit memories (Schwabe, Wolf, and Oitzl, 2010). Posttraumatic stress in adults contributes to the development of amnesia as the neurons in the hippocampus are destroyed.
Current research shows that amnesia can be caused by biological forces and not through detectable brain damage through the process of dissociation (Bidzan, 2017). The biological factors that contribute to amnesia by causing the arousal of the various parts of the brain such as the hippocampus, the amygdalae, and the prefrontal cortex. Exposure to stress factors causes the secretion of stress hormones, which lead to the arousal of the hippocampus. The function of the amygdalae is to control the emotional reaction to the stress factors and therefore contributes to the arousal of the parts of the brain. Excessive arousal affects the normal functioning of the prefrontal cortex contributing to its arousal that induce amnesia. Despite the identification of biological factors in the development of amnesia, there is a need to investigate the concept further through research studies.
Intracranial surgery is another concept that refers to the process of treating temporary lobe epilepsy. It involves the restructuring of the temporal lobes but can affect normal cognitive functioning of the brain (García-Castro, 2017). The memory functions are inhibited when the hippocampus part of the brain, which is responsible for memory formation and processing, is damaged. Depending on how severe the condition is, the surgery can be an effective intervention, which can improve the cognitive development of an individual but can also lead to the development of amnesia because of the damage to the hippocampus.
The study of amnesia is essential for the understanding of the process of memory loss among individuals with the condition. It helps in identifying the different parts of the brain, and their functions which affect memory processing. Various risk factors cause the development of amnesias such as brain damage and acute prolonged stress, which lead to biologically induced amnesia. The study of amnesia provides insights into the normal functioning of the brain and shows how the functioning is affected by various changes that can lead to memory loss. It helps in understanding the neurological effects on the regular and abnormal cognitive functioning, and how the brain is involved. It also provides insights into the association between the hippocampus, the temporal lobes, and how their damage can lead to memory deficits and delay.
Recent research studies have shown that physical exercises have positive biological and psychological effects on the brain. They affect the cognitive functioning of the brain and promote a condition of wellbeing. In addition to reducing stress, physical exercise benefits the brain by making it active. Involvement in regular physical activities also increases blood flow to the various parts of the body including the brain. Lack of adequate oxygen in the brain is a causative factor of amnesia. The role of physical exercise as a preventative measure for amnesia should be investigated further to provide full details on how physical activity affects cognitive functioning and how it can help prevent amnesia. In addition, it is important to investigate its potential negative impact on the brain.
Bidzan, M. (2017). Biological Bases of Dissociative Amnesia. Acta Neuropsychologica, 15(1), 1-11. doi: 10.5604/12321966.1233199
García-Castro, Gonzalo. (2017). Developmental Amnesia: Contributions to the Study of Memory. 10.13140/RG.2.2.31457.10087.
Eichenbaum, H. (1993). Memory, amnesia, and the hippocampal system. MIT press.
Schwabe, L., Wolf, O. T., & Oitzl, M. S. (2010). Memory formation under stress: quantity and quality. Neuroscience & Biobehavioral Reviews, 34(4), 584-591.
Squire, L. (2009). The Legacy of Patient H.M. for Neuroscience. Neuron, 61(1), 6-9. doi: 10.1016/j.neuron.2008.12.023
Smith, C., Frascino, J., Hopkins, R., & Squire, L. (2013). The nature of anterograde and retrograde memory impairment after damage to the medial temporal lobe. Retrieved from http://whoville.ucsd.edu/PDFs/489_Smith_etal_Neuropsy_2013_Combined.pdf
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