Things That May Contribute to Memory Loss - Essay Example

Brain Damage In August 1953, 27-year-old Henry Molaison lost memory that emanated from undergoing mental surgery (Schaffhausen, 2007). During then, he was suffering from epileptic seizures for many years (Schaffhausen, 2007). A surgeon advocated that Beecher Scoville remove a part of his brain that included the hippocampus, the amygdala, and some cortices (Schaffhausen, 2007). The amygdala and the hippocampus structures belong to the medial temporal lobe most essential in critical declarative as well as memory (Plotnik,& Kouyoumjian, 2011). The operation was successful because during then seizures reduced. However, it led to a critical condition whereby HM faced a dense memory loss (Schaffhausen, 2007). The surgeon realized his patient had become amnesic and referred him to another neurosurgeon Wilder Penfield and neurophysiologist, Brenda Milner (Schaffhausen, 2007). It was after a detailed examination that it dawned to them that, the removed hippocampus was essential for the creation of memories. Consequently, prompted scientists then to publicize this information with the intention of creating awareness aimed at preventing occurrence of the same procedure. HM had lost his ability to create new memories, he lacked the ability to consolidate any new information that he was exposed to. It was however intriguing that he had retained memory on things that he had learnt during the 27 years before the operation (Plotnik & Kouyoumjian, 2011). Surgeons concluded that HM was suffering from anterograde amnesia, which refers to a condition where damage to the brain affects storage of new information just after the damage (Plotnik & Kouyoumjian, 2011). This was evident from the fact that HM could recall events just before the trauma and not afterwards. Following the observations on HM, it will be inappropriate to claim that the medial temporal lobes are the principle sites of memory. This is because he had retained other forms of memory such as the short-term memory. Therefore, researchers concluded that there were variety forms of memory. They also concluded that different parts of the brain regulated these respective memory forms. HM could not have retained his long-term memory as well as the short-term memory, if indeed the medial temporal lobes were the principle part of memory. This inspired scientists to investigate how the brain worked regarding retaining of memory. Human brain is three times that of other mammals besides having a more complicated structure of living systems. Brain is approximately 1.5 kg in weight, soft and pinkish in colour as well as little white in the interior. The pinkish outer layer also goes by the name grey matter, which turns into grey once a person dies. The interior contains many structures responsible for communications [purposes as well as interpretation. The pinkish outer layer takes charge of computation factors as well as thinking problems. The brain consists of 50% water; the water is from the cytoplasm of brain cells. 10-12% of the brain’s mass comprises of fatty acids and 8% is protein (Cater, Aldridge, Page, Parker, Frith, & Shulman, 2009). The body contributes to only 2% of body weights but it consumes 20-25% of the nutrients, glucose, and oxygen from the body (Cater, Aldridge, Page, Parker, Frith, & Shulman, 2009). Constant blood flow nourishes the brain with these essentials. Thick muscles of the skull suspend in cerebrospinal fluid and they protect the soft tissues of the brain. It is however still vulnerable to damages and diseases because of its sensitive and delicate nature (Cater, Aldridge, Page, Parker, Frith, & Shulman, 2009). The three common parts of the brain include the cerebrum, celleberum, and brain stem (Cater, Aldridge, Page, Parker, Frith, & Shulman, 2009). The brain stem comprises the midbrain, medulla, and pongs. It is responsible for breathing, digestion and the heart beat functions. It also connects the brain to the spinal cord as well as the rest of the body. The celleberum is responsible for body balance, processing procedural memories as well as language, and emotion functions. The celleberum is also responsible for motor functions and attention. The cerebrum is the largest component of the brain occupying 75% and is responsible for 85% of the weight of the brain (Cater, Aldridge, Page, Parker, Frith, & Shulman, 2009). A longitudinal groove divides the cerebrum into two hemispheres. A bundle of nerves called the corpus callosum connects the two hemispheres and facilities communication between the two. As much as the two hemispheres are similar, they perform different functions. The left hemisphere controls the right part the body whereas the right part if the brain controls the left part of the body (Sukel, 2012). Covering the outer layer of the cerebrum is the cerebrum cortex. This tissue gives the brain its wrinkled nature. This cortex folds into grooves to increase the surface area for neuron. This ensures faster and efficient transfer of impulses. The cerebrum is divided into four lobes, the frontal lobe is essential for initiating ad controlling motor movements ,higher cognitive skills, emotions as well as personality. The parental lobe is essential for sensory processes, attention, and language. Any damage to this part will lead to an imparenement on the ability to read and understand written or spoken speech. Occipital lobe is necessary for understanding shapes and odour, it helps process visualized information. The temporal lobe integrates information from other senses and processes auditory information. From this, it is evident that the brain has different parts that function differently (Maharg, & Maughan, 2011). It will be wrong to say that the hippocampus of the temporal lobe is the principle site of memory because without it other parts of the brain will continue to do their part effectively. The medial temporal lobe consists of the olfactory cortex, amygdala, as well as the hippocampus. Collectively, these structures belong to the limbic system. The olfactory system begins at the top of the nasal cavity. Its receptors are made of ciliated epithelia, which has numerous receptors and they are responsible of sensing an array of odours. It is vulnerable to sheering force in head trauma (Journal of Cognitive Neuroscience, 2013). When exposed to injury it will lead to the loss of the sense to smell. The amygdala is responsible for the twisting lurch one feels in the stomach when expose to fear. The visual, auditory, and somatosensory cortices are the main inputs to Amygdala. The amygdala must get highly processed sensory output to be able to recognize signal that symbolize danger. The amygdala must control the unconstrained system to deliver the sympathetic response. The outputs of the amygdala include the hypothalamus and the brain stem autonomic cells. An epileptic surgery provides an opportunity to stimulate various parts of the brain to determine the extent of the problem. If this process stimulates the amygdala, it results in intense hallucinations as well as fear in the patient ( Carlozzi, 2013). The hippocampus is necessary for declarative memory but it is not involved with working memory, procedural memory, or memory storage. Disruption of the hippocampus will lead to impairment of the ability to create declarative memory. Creation of memory in the hippocampus follows a continuous pathway, which begins in the sensory cortices, transverses the hippocampus and then returns to sensory cortex. Other parts of the cerebrum include the basal ganglia which are the cerebral nuclei rooted in the context, the hypothalamus takes responsibility for appetite, reproduction as well as defensive behaviours. The thymus is also part of the cerebrum and is responsible for prioritizing and passing sensory information to the cerebral cortex There are three types of memory in the brain. Sensory memory involves the retention of auditory or visual stimulus for a short period. Sometimes one remembers some sensory information like smell, feelings, and touch after a long time. This is possible because the brain can encode some sensory information to the next level, which is the short-term memory. If they are interesting, images and one that a person wants to remember for a lifetime, the brain encodes it to the long-term memory. For the brain to encode sensory memory into other types of memory, it is necessary to give it the attention stimuli. The brain will thereafter filter the information to keep from the information that needs discarding. Short-term memory is also a working memory because it is where we derive information when we want to use it. Retention time limit in the short memory is thirty minutes and if it the brain does no encode the information into the long-term memory, it is lost (New Scientist, 2012). The brain stores some information in the long-term memory but uses it in the short memory state. Through a lot of rehearsal and repetition, the brain encodes short-term memory to long-term memory. Maintenance rehearsal holds information in the short-term memory, any disruption on rehearsals will interfere with short-term memory. Elaborate rehearsals will contribute to deeper long-term memory and easier retrieval. The long-term memory has contributed greatly to ability to learn as well as intelligence. Long-term memory has infinite capacity and one can even derive information learnt in the childhood days. Declarative and procedural memory is subsets of long-term memory. Declarative memory refers to the information on the things that one has experienced, as well facts, figures, and people’s names. Finally, this procedural memory is the most durable form of memory. It involves skills, habits, and actions that are a result of continuous rehearsal. The hippocampus is necessary for storing this information with the help of the cerebrum. In HMs case, it is the declarative and the procedural subsets that will be analysed. After the surgery, HM could remember events before the surgery. This shows that he had not lost all his memory. This therefore ruled out the thought of the hippocampus being responsible for retaining and coordinating short memory. It was however interesting to note that HM could learn new skills such as playing the guitar as well as learning new games and he could retain this information .He could however not retain information that included faces, named or figures. HM could remember events from the past such as the president of 1950s as well as how he looked like, but could not remember events from the previous night(Schaffhausen, 2007).This showed he could not consolidate some information from the short-term memory to the long-term memory after his hippocampus was removed. The fact that HM could remember old memories raised concerns because his hippocampus had been remove dandy it was responsible for long-term memory.HM case somehow proved that the hippocampus was essential for the storage of long-term memory but was not responsible for its revival (Plotnik,& Kouyoumjian, 2011). The basal ganglia and the cerebrum remained intact in the brain of HM and that is the reason why he could retain procedural memory. The prefrontal cortex enabled the functioning of working memory. This showed that it was his inability to stabilize information he had acquired into the long-term memory, which hindered him from consolidating new information (Plotnik, & Kouyoumjian, 2011) . This features stimulated the study of diseases and disorders of the brain The hippocamia is vulnerable to diseases such as the Ischemia, epilepsy, as well as Alzheimer’s disease. Ischemia is a result of obstruction of blood flow as well as deprivation of oxygen to the hippocampi. A stroke can have cause effect, to cause an interference with the memory there must be a bilateral damage on the hippocampi (Plotnik, & Kouyoumjian, 2011). Situations that prevent blood and oxygen flow to the hippocampi can cause a deficit in memory. The pathology of temporal lobe epileptic looks similar to this condition. Temporal lobe epilepsy is due to consistent epileptic seizures that originate from the temporal lobe of the brain (Schapiro, McClelland, Welbourne, Rogers, Lambon, 2013). The seizures cause impairment to the sense to smell and causes one to sense an odour that does not exist. The memory also suffers interruption and this condition requires surgery as a form of treatment. Seizures can be partial or generalised. Partial seizures result from the amygdala and the hippocampus, in simple partial seizures; the seizures do not affect the patient’s level of consciousness (Zeman, Kapur, & Jones-Gotman, 2012). Simple seizures do not necessarily proceed to generalized seizures and the people affected by it, rarely seek any medical attention. Complex partial seizures however affected the consciousness of the patient. The start by affecting a small part of the temporal lobe and eventually progresses to other parts .Such seizures alter speech, movement abilities, as well as other automated activities ( Zeman, Kapur, & Jones-Gotman, 2012). Secondary generalizes seizures affect the temporal lobe then spreads to all parts of the brain. Since the temporal lobe also functions to retain short-term memory, complex partial seizures and generalised seizes cause amnesia for the period of seizure. This makes the patients even fail to remember that they had the seizures. Effects of the seizures include depression, change in personality as well as memory impairment (Zeman, Kapur, & Jones-Gotman, 2012). The memory is affected depenfumg on the extent of the effect on the brain, if it has spread to the whole brain; it will be more servers compared to when it has affected a small part of the brain. This also explains that the temporal lobe is not the principle site for brain memory. This is because it is evident from the fact that people with partial seizures do not lose their conscious state. Other things that may contribute to memory loss may include encoding failure. This is where one was not paying attention hence could not absorbed the information well. Insufficient clues will also decrease the ability to retrieve the information. Retroactive and proactive cues cause interference, old memory may interfere with new memory, and the new memory corrupts old memories. Memory can however be enhanced through, through proper rehearsal as well as well avoiding any forms of interface (Romero, Anna, & Steven, 2007). References Carlozzi, Noelle E., Grech, Julie., Tulsky, David, S. (2013). Memory functioning in individuals with traumatic brain injury: An examination of the Wechsler Memory Scale–Fourth Edition (WMS–IV). Journal of Clinical & Experimental Neuropsychology. 35(9), p906-914. 9p. Carter, R., Aldridge, S., Page, M., Parker, S., Frith, C. D., Frith, U. & Shulman, M. B. (2009). The human brain book. London: DK Pub. Maharg, P., & Maughan, C. (2011). Affect and legal education: Emotion in learning and teaching the law. Farnham, Surrey, England: Ashgate. Plotnik, R., & Kouyoumjian, H. (2011). Introduction to psychology. Belmont, CA: Wadsworth/Cengage Learning Romero, A. & Steven K. 2007. Psychology Demystified. New York City: McGraw Hill Schaffhausen, Joanna. 2007 "The Day His World Stood Still." Brain Connection. Schapiro, Anna C.; McClelland, James L.; Welbourne, Stephen R.; Rogers, Timothy T.; Lambon Ralph, Matthew, A. 2013. Why Bilateral Damage Is Worse than Unilateral Damage to the Brain. Journal of Cognitive Neuroscience. 25(12), p2107-2123. 17p. Sukel, Kayt. 2012. The amazing memory marvels. (Cover story). New Scientist. Vol. 215 Issue 2878, p34-37. 4p. Zeman, A., Kapur, N., & Jones-Gotman, M. (2012). Epilepsy and memory. Oxford: Oxford University Press. Read More