The Amygdala is located at the frontal portion of the temporal lobes that are close to the hippocampus. The amygdala is responsible for performing several functions such as the storage of information related to emotional events and emotional memory. It can perform other functions such as the storage of long-term memory and helps in the discernment of danger or when there is anything that appears somewhat frightening. The study of the Amygdala has been done by analyzing patients that have undergone amygdala damage. Patients that have had their amygdala damaged have experienced several difficulties with memory formation, learning and remembering, emotional sensitivity, depression, and gloom. SM is a patient that had her amygdala damaged and experienced several negative effects from the damage. The study of SM was conducted by Dr. Ralph Adolphs. This paper considers the contributions of Dr. Ralph Adolphs in the understanding of the amygdala and its relation to memory, emotions, fear, decision-making abilities, and psychopathy.
The amygdala is a part of the limbic system which is located right below the lobes of the brain. Hormones are produced, appetite is controlled, and the body temperature is controlled in the amygdala. The main parts of the limbic system are the hypothalamus, hippocampus, and the amygdala. The amygdala and the hippocampus work together to ensure that there is accurate processing of emotional memories. While the amygdala encodes emotions, the hippocampus is used to store the context such as the situation, the people, and the things that took place.
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The functioning of the Amygdala has been a hotly debated topic, especially when trying to understand its specific functions. SM was a patient that had bilateral amygdala damage and showed impairment in the ability to be able to recognize fear from various facial expressions. SM increasingly showed that she was not afraid of many things and her ability to recognize fear had diminished. This raised the question regarding whether the damage of the Amygdala played a significant role in the emotional and memory impairment of the patient. Mechanisms which amygdala damage compromised fear recognition was not identified.
Adolphs et al. (2005) made significant contributions towards the understanding of the working mechanism of Amygdala through the patient SM. The study noted that one of the reasons why there was a failed function in the amygdala was that the patient had the inability to make use of information from the regions of the eye when one is judging emotions. The defect was traced to have occurred as a result of spontaneous fixation of the eyes when the patient was viewing different faces. The study further noted that while SM seemed to look normal at the region in all facial expressions, she failed to recognize facial expressions because she was not keen with the eyes which can be named as highly important in identifying emotion. The recognition of fear and faces by SM became somewhat normal when she looked at the eyes. The explanation by Dr. Ralph Adolph showed that the amygdala damage decreased the responsiveness of an individual to various emotions such as fear. The study opened up a new approach for the studying of the amygdala and how it can be applied in the study of memory and emotions.
Fearlessness and Psychopathy
Fear can be described as a wired emotion reaction that has evolved throughout history in order to protect living organisms from any perceived threat. The circuitry of the brain through the amygdala has been found to have a significant effect on fear by stimulating either flight or fight. The amygdala is also responsible for other positive emotional states such as happiness and excitement. The reaction of fear starts in the brain and then spreads to other parts of the body in order to make an adjustment for the best flight reaction or defense. The fear response starts in the amygdala which normally activates when one sees another human face with emotion. The stimulation of the amygdala is more pronounced when an individual has fear and anger. The threat of a dangerous animal can trigger a response from the amygdala which resultantly activates the body in preparation for motor or flight.
The study of fear has presented as a key issue among psychiatrists because the absence of fear can lead to an individual engaging in dangerous acts. Fearlessness can be associated with the psychopathy because the absence of experiencing fear results in other problems such as superficial charm, dishonesty, or engaging in dangerous acts which can be deadly. However, the contribution of fear of psychopathy is a hotly debated topic. The severe effects of the damage of the amygdala, experience of fearlessness and psychopathic personality were examined by Lilienfield et al. (2018). SM was studied in the experiment because she had experienced amygdala damage and the result was that there was an absence of fear. The study further investigated the heroic acts and psychopathy experiences of the patient. Compared to the average population SM recorded higher levels of self-reported fear, self-control, and elevated levels of heroism. However, she did not show high levels of psychopathy because she did not show high signs of meanness or cold-heartedness. The study established fear deficits may not be a significant yield to a full clinical diagnosis of psychopathy.
Emotional Events and Memories
The amygdala plays a big role in the storage of memories that can be associated with strong emotions. Emotions that are usually associated with joy, grief, love, or shame are usually difficult to forget because they are stored in the amygdala. These memories are usually permanent which shows that there is an interaction among various parts of the brain such as the neocortex, the hippocampus, and the amygdala. Such an interaction is important to maintain stability in the memory and ensure that it is effectively retained over some time.
Emotional events are usually memorable compared to events that are neutral. One of the reasons why emotional events become highly memorable is because of the interaction of the amygdala with the memory. A study by Inman et al. (2018) tried to establish the relationship between the Amygdala and the memory by focusing on direct electrical stimulation of the amygdala and trying to identify whether there was an enhanced declarative memory. The study established that the stimulation of the amygdala led to an improvement of memory compared to the control images where patients were given recognition-memory tests. The study by Inman et al. (2018) adds to the baseline developed by Adolphs which indicated that the amygdala plays a big part in the emotional process. The analysis showed an additional function that exists between the relationship of the amygdala, emotions, and memory.
The Amygdala and Decision-Making
The amygdala is usually made of multiple sub-nuclei which receive input directly and indirectly from different sensory systems. These major connections with the insula play a big role in emotional awareness in man. However, lesion studies have demonstrated that the amygdala severs a big role in fear conditioning in both animals and man. The study of modern neuroscience has shown a detailed understanding of the mechanism of the amygdala in animals. The effect of the rare lesions of the amygdala has been associated with a loss of both the subjective experience of fear and capacity to detect the expression of fear by other individuals. Such impairment can result in an impairment of decision-making skills and social cognition.
The study of the significance of the amygdala in decision-making was analyzed by Charpentier et al. (2015). The study involved low-anxious individuals who were investigated in their ability to alter decision-making abilities in relation to emotional cues. The participants engaged in gambling decisions that were preceded by non-emotional and emotional primes. The study showed that the low-anxious individuals showed loss aversion when they went through emotional conditions. The study showed that the modulation of the decision-making process was accompanied by an emotional increase in the stimulation of the amygdala-striatal functional connectivity. This led to a resultant corresponding behavioral effect. The study by Charpentier was consistent with other studies which showed that the loss of the amygdala led to significant loss of emotions. Individuals that could not access their emotions such as fear when making various decisions were likely to engage in behaviors that were highly risky.
The study by Charpentier (2015) shows that the damage to the amygdala can result in individuals taking bigger risks that could have potentially small gains. It shows that the amygdala is thus involved in emotional response and decision making. Individuals that had their amygdala did not show significant control with their gambling and portrayed risky behavior when gambling. One reason why these individuals have poor decision-making abilities is due to the loss of fear. Without the emotion of fear, people can easily engage in decisions and actions that are quite risky.
Fear and PTSD
The amygdala also performs various functions regarding enhancing memorable experiences. Apart from simply being involved in the strengthening of the emotional content of memories, the amygdala plays a significant role in the formation of new memories that are related to fear. Fearful memories are usually formed after several repetitions. This creates a mode of learning known as fear learning that occurs after memory formation, memory-synthesis, and recall. The understanding of how the amygdala processes fearful memories find its application in understanding advanced memories that cause a significant amount of fear such as post-traumatic stress disorder (PTSD). This is a condition which affects many veterans and the police as a result of exposure to trauma. Traumatic situations involve the amygdala and this leads to the strong retaining of the fearful thoughts and emotions. A proper understanding of how memories are formed in the amygdala can thus help in treating conditions severe conditions such as post-traumatic stress disorder.
PTSD is a unique psychiatric condition where an individual has mental images of horrific incidences about past experiences. The experience of these life-threatening events produces negative physical and mental outcomes. Post-traumatic stress disorder has been found to occur as a result of a hyper-functional amygdala. Diamond and Zoladz (2016) addressed the main issue by trying to identify whether symptoms in PTSD have been caused by having an impaired and dysfunctional amygdala or they have been caused by one that is over-sensitized and hyper-functional. The study suggested that the symptoms that are associated with PTSD are due to a hyper-functional amygdala.
The association between the Amygdala and major depressive disorder (MDD) and post-traumatic stress disorder (PTSD) was analyzed by Shou et al. (2017). The study established that cognitive behavioral therapy increases the amygdala connectivity with the various cognitive control networks in both PTSD and MDD. The study showed that the amygdala plays a huge role in an individual having symptoms of PTSD and MDD. One of the best treatment options is thus to make use of CBT treatment that would result in changes in connectivity between the amygdala and brain regions that are involved in cognitive control of the brain. The study of various ways to reconnect or reconstruct memories in the amygdala can thus play a significant role in helping patients that increasingly suffer from PTSD.
In conclusion, the study of Dr. Ralph Adolphs first identified that effects of amygdala damage in the loss of one’s ability to detect the expressions of fear by other individuals. This opened up to a huge body of research over the years that have tried to understand the role of the amygdala in fear, emotion, and memory. One of the dangers of having amygdala damage was that it induces fearlessness and people can participate in high risks and poor decision-making. The nature of fearlessness due to a damaged amygdala can also result in psychopathy tendencies. Amygdala is associated with the storage of strong emotions and memories. However, harboring emotions that are strong, negative, and fearful has been associated with symptoms of PTSD.
References
Adolphs, R., Gosselin, F., Buchanan, T. W., Tranel, D., Schyns, P., & Damasio, A. R. (2005). A mechanism for impaired fear recognition after amygdala damage. Nature , 433 (7021), 68.
Charpentier, C. J., Martino, B. D., Sim, A. L., Sharot, T., & Roiser, J. P. (2015). Emotion-induced loss aversion and striatal-amygdala coupling in low-anxious individuals. Social cognitive and affective neuroscience , 11 (4), 569-579.
Diamond, D. M., & Zoladz, P. R. (2016). Dysfunctional or hyperfunctional? The amygdala in posttraumatic stress disorder is the bull in the evolutionary China shop. Journal of neuroscience research , 94 (6), 437-444.
Inman, C. S., Manns, J. R., Bijanki, K. R., Bass, D. I., Hamann, S., Drane, D. L., ... & Willie, J. T. (2018). Direct electrical stimulation of the amygdala enhances declarative memory in humans. Proceedings of the National Academy of Sciences , 115 (1), 98-103.
Lilienfeld, S. O., Sauvigné, K. C., Reber, J., Watts, A. L., Hamann, S., Smith, S. F., ... & Tranel, D. (2018). Potential effects of severe bilateral amygdala damage on psychopathic personality features: A case report. Personality Disorders: Theory, Research, and Treatment , 9 (2), 112.
Shou, H., Yang, Z., Satterthwaite, T. D., Cook, P. A., Bruce, S. E., Shinohara, R. T., ... & Sheline, Y. I. (2017). Cognitive behavioral therapy increases amygdala connectivity with the cognitive control network in both MDD and PTSD. NeuroImage: Clinical , 14 , 464-470.
