Researchers Atkinson and Shiffrin (1968) suggested ‘the multistore model’, consisting of the three key types of memory stores: the sensory store, the short-term store (STS) and the long-term store (LTS).
In order for memory to move from sensory to short-term, attention was needed, for short-term to long-term, rehearsal was needed, and to access long-term memory, retrieval was required. Furthermore, scientists have been able to map out the many different structures of long-term memory.
LTM is firstly divided into two different systems: explicit memory- consisting of fact-based information, which can be recovered, and implicit memory- consisting of memories that we aren’t consciously aware of. Explicit memory is further divided into two ‘subsystems’: semantic memory- used for general knowledge, and episodic memory- memory of personal experiences and events. In contrast, implicit memory can be divided into numerous ‘subsystems’. These include procedural memories- consisting of how to do things, and emotional memories- consisting of memory of how emotional states.
Scientifically speaking, the temporal lobe is where memory is stored. This is where the brain stores everything one remembers. The hippocampus is also responsible for a part of memory. This is where the process of new memories is introduced into long-term storage. If the hippocampus is damaged or absent, one would not remember what is happening in the present, but only remember what happened in the past. It’s in the frontal lobe that memory is recalled – this is where the brains explores and recalls important information.
... keep it in our memory for a very short time. Long term memory corresponds to persons ability to remember information for as long as few years ... simply remains stored up. The essence of brain power consists in its ability to relate the abstract concepts to the memories of physical ...
In this essay, I’m going to look at three cases, which study how memory is affected after a negative impact, such as an accident or a virus. The first study I’m going to look at is HM’s case. HM was born in America in 1926. He fell off a bicycle at the age of 7, injuring his head. Three years later, he began suffering from minor epileptic seizures. By the age of 27, the frequency and severity of the attacks had prevented him from leading a normal life (it was taken into account that his family had a history of epilepsy).
In the 1950s, HM was having approximately 10 seizures as well as blackouts a week.
After many unsuccessful drugs recommended, he was suggested Dr. Scoville, who localized his seizures in the temporal lobe. Scoville then performed an experimental procedure called a bilateral medial temporal lobe resection. He therefore removed a large percentage of the temporal lobe from both left and right hemispheres, which resulted in extensive and severe damage. Tissue was taken out of the temporal lobes on the inner surface of the brain (extending 8cm), therefore the amygdala, two thirds of the hippocampus, the entorhinal and perirhinal cortices were removed.
Although the surgery was successful in stopping the frequent epilepsies (he only had about two seizures a year), HM’s memory was diagnosed with profound anterograde amnesia and partial retrograde amnesia: he could no longer store new memories – most of his memories that dated from before the operation remained intact (partial retrograde amnesia); he couldn’t transfer new semantic and episodic memories into his long-term store; he was able to have a normal conversation, but forgot what it was about almost instantly.
Thanks to this case, psychologists and scientists learnt about the relationship between the brain and memory. For example, HM was able to retain a few memories of events that happened prior to the operation. This indicates that the medial temporal region, including the hippocampus, isn’t the permanent site of storage, but plays a critical role in the way that memories are organized and then stored in a different location in the brain. They could then further deduce that the medial temporal region with the hippocampus is important for forming, organizing, consolidating and retrieving memory.
The hippocampus is a small structure in the brain that is surrounded by the temporal cortex. It is thought to play a major role in learning and memory. Many experiments have been done to study the impact of lesions to the hippocampus to determine how it affects learning in rats. Observational studies have been done that look at human patients with damage to the hippocampus to see how they function ...
Furthermore, HM’s case and similar cases with amnesia provide evidence that the brain has multiple memory systems that are supported by distinct brain regions. The second study is the case of English musician Clive Wearing. In his mid-forties (1985), he was diagnosed with a brain infection (herpes encephalitis) – attacking his central nervous system and affecting parts of his brain linked with memory. One of the affected locations was the hippocampus, which is the crucial area where the transition of memories from short-term to long-term memory takes place.
This resulted in leaving him with a memory span of a few seconds (between 7 and 30 seconds, worst amnesia ever recorded).
Any new information was erased from his memory almost instantly. He therefore suffers from both anterograde and retrograde amnesia. He spends every single day ‘waking up’ every 20 seconds, every time regaining full consciousness. He can’t remember much of his life before the infection. He can remember he has children from an earlier marriage, but can’t recall their names. Every time he sees his second wife, he greets her lovingly, not remembering that she’d been in the room a few minutes before.
Furthermore, although he can remember the name of a food, he won’t be able to recognize it with taste, as he’s forgotten. Wearing is still capable of playing the piano and conducting music he already knew prior to the illness, as these skills are part of his implicit memory. The fact that he can still play shows evidence of a distributed memory system, meaning memory is not only linked to one part of the brain. His emotional memory remained intact, shown by the way he greets his wife every time he sees her. When taking an MRI of his brain, damage can be seen in not only the hippocampus, but also in some areas of the frontal regions.
Clive Wearing’s case shows evidence about the biological foundation of different memory systems. For example, the damage seen at the hippocampus and the frontal regions could indicate that his retrograde amnesia and be explained as a trauma that interrupts the consolidation of memory. The third case I’m going to look at is the Sperry study. In the 1900s, there was a suspicion involving the brain having the ‘language centre’ in the left hemisphere and thanks to people with certain brain injuries, this was proven.
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Researchers and psychologists noticed that people with lesions in specific areas in the left hemisphere lost their ability of speech. In 1968, Roger Sperry discovered evidence for this study. He used ‘split-brain’ patients and carried out many experiments to discover the usage of the right and left hemispheres. In the 1960s, people who suffered from a specific kind of epilepsy had no other cure than to cut off the connection between both hemispheres: the corpus callosum. To stop the epilepsies, the corpus allosum was cut, meaning the excessive signalling of nerve cells from one hemisphere to another was no longer able to spread to the other hemisphere. By doing this surgery, patients were able to live an almost normal life, until Sperry noticed strange facts about the patients. His experiment involved 11 participants, who’d all undergone the surgery of the disconnection of the cerebral hemispheres. The reason why they had to undergo the operation was due to advanced and severe epilepsy that was unresponsive to medication prescribed. Sperry created two tasks which had to be completed by his participants.
The first task was used to send visual information to one of the hemispheres. This was done by blindfolding one of the participant’s eyes and asking them to fix a point at the middle of the screen with their other eye. The researchers noticed that when a word flashed across the left side of the point for less than a tenth of second, it would transfer to the right hemisphere, and the patient would be unable to name the word. Whereas if the word flashed on the right side, it would transfer to the left hemisphere, and the patient would be able to name the word.
The second task was used to send tactile information to one of the hemispheres. This was done by presenting an object to one of the hands and then the participant would have to state the object. If the object was placed in the left hand, the participant would not be able to name it, whereas if the object was place in the right hand, the participant would be able to name it. This study indicated that after a split-brain operation, each hemisphere would still function, but one would be unaware of what the other hemisphere has learnt or experienced.
The aim of this of this study was to investigate the accuracy of long term memory for a common object and more precisely to examine the differences between memory recognition and recall. Six participants took part in the experiment, three were assigned to the recognition task and three to the recall. The recognition group were required to answer yes or no to a series of questions relating to ...
Furthermore, the study demonstrated that the left and right hemispheres are specialized in different tasks: the left side being specialized in analytical and verbal tasks, and the right side being specialized in space perception tasks and acoustics. In conclusion, these studies clearly show how biological factors affect the cognitive process of memory. There is strong evidence that damage to certain parts of the brain results in issues involving memory, thanks to cases such as HM and Clive Wearing.
Biological factors such as amnesia and split-brain have a huge impact on human memory: for example, damage in the hippocampus results in problems transferring short-term memory into long-term memory, creating anterograde amnesia and in some cases retrograde amnesia. In addition, when disconnection of the cerebral hemispheres takes place, no information passes from one hemisphere to another, leaving both hemispheres unaware of what the other is doing. From these conclusions, we can deduce that cases which suffer from these abnormalities cannot live a normal life on a daily basis.