Since episodic memory is greatly impaired in the absence of a medial temporal lobe, by investigating the effectiveness of the brain network supporting episodic memory function in the absence of unilateral medial temporal lobe, new therapies for people with medial temporal lobe dysfunction-related memory impairment can be developed and used to possibly improve their episodic memory even without a fully functional medial temporal lobe. In this study, the aim was to understand how the brain supports normal episodic memory function without unilateral medial temporal lobe structures.
By using a whole-brain fMRI, the effective episodic memory encoding network was investigated in patients who had a normal range of memory function in the absence of one MTL structure. In addition, all subjects underwent a standardized neuropsychological examination where verbal memory performance was assessed by the Korean version of the Rey Auditory Verbal Learning Test (KAVLT), and nonverbal visual memory performance was assessed by the Korean version of the Rey Complex Figure Test (KCFT) (Jeong, Lee, Kim, & Chung, 2019).
To investigate the differences in regards to brain function of the two groups, the researchers in another study compared the brain activities of each patient group with the healthy controls for the word recognition performance task and the figure recognition performance task. In this comparison, the healthy control group showed a significantly greater activation in the inferior frontal areas during both successful word and figure encoding (Jeong, Lee, Kim, & Chung, 2019). The study found that there was not a statistical difference in the word recognition performances among the subject groups, but that there was a statistically significant difference in the figure recognition performance between the two subject groups. Therefore, this suggests that the whole-brain memory network in patients who have a normal range of memory ability was characterized by altered patterns of regional activation together with enhanced functional interactions across widespread cortical areas (Jeong, Lee, Kim, & Chung, 2019).
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Some limitations to this study include the fact that the researchers only included patients who had at least a low average or a higher level score of memory capacity and general intelligence. This is problematic because IQ does not necessarily tell the whole story about a person and a whole demographic of people are excluded from the study. In addition, those patients who had a poor outcome of the surgery or who showed severe dental metallic artifacts were also excluded. Once again, a whole demographic of people are being excluded from the study just because they have dental metallic artifacts and also the people with a poor surgery could have shown a different perspective to the researchers that they may not have seen with the other people who were included. Finally, only 35 subjects were studied, which is a relatively small amount and should be taken into consideration before generalizing the results to an entire population.
Other limitations were also shown in regards to the subjects picked to be in the healthy control group in the study. This group of subjects was chosen by matching the age and number of years of education to the medial temporal lobe resection group. Therefore, the control group was not truly picked randomly as everyone in the population did not have an equal chance of being picked. This could affect the results of the study especially when comparisons were being made between the two groups on verbal and nonverbal memory ability.
However, there were also a few strong points about the study and its experimental design. First, as shown in both of the articles described above, Alzheimer’s disease profoundly affects the memory and causes behavioral and psychological problems for those diagnosed, which provides many hardships in trying to go about a normal day and live an everyday normal life. Studies have shown that a personal assistant such as a robot can decrease stress, anxiety, and depression in patients who have trouble doing various tasks on their own and need the constant assistance of someone or something else. In addition, because many of the brain structures work together to perform critical human functions such as memory, there may be more than one region involved in creating the various types of memories such as procedural, semantic and episodic memory.
Both journal articles reviewed in this paper involve the role of episodic memory, or recollection of autobiographical events involving a specific time or place. The hippocampus and temporal lobes are vitally important in the encoding, storage, and retrieval of episodic memory, and as stated previously, can cause impairment if one medial temporal lobe is missing. According to research studying 33 individuals with dementia of Alzheimer’s type (DAT), episodic memory deficiency in those affected by the disease more so reflects an inhibited ability to learn, rather than the assumed impairment of remembering or increased rate of forgetting (Tromp, Dufour, Lithfous, Pebayle, & Després, 1981).
This study suggests that complex brain networking, involving a plethora of neurological regions, is involved in the development and recall of autobiographical memory. Because of this finding, it may be possible to salvage a person’s episodic memory through activating other areas of the brain while those neurons are firing and the memories are being created. This could lead to less detrimental effects to a person’s memory when a person’s medial temporal lobe or other brain structure is damaged due to Alzheimer’s or other degenerative diseases as this is where some types of memories are created and kept.
Although both of the studies discussed above have their limitations, they both show convincing evidence of ways to treat the consequences of many degenerative brain diseases such as Alzheimer’s disease. By potentially allowing a person to have a working memory, specifically episodic memory, and by decreasing a person’s stress, anxiety and/or depression using a personal assistant such as a robot, their everyday life may no longer be compromised, and the effects of these diseases may not be as detrimental as they once were. With these studies taken into account and further research being developed, the potential to increase the wellbeing and quality of life of people affected by degenerative brain diseases may be within reach, and less people may have to suffer the many consequences that comes with developing a severe brain disorder.
