VonOlivia Guy-Evans, published on May 09, 2021
VonSaul Mcleod, PhD
The central theses
- the tonsil inlimbic systemit plays a key role in how animals assess and respond to environmental threats and challenges, assessing the emotional significance of sensory information and triggering an appropriate response.
- The main job of the amygdala is to regulate emotions like fear and aggression.
- The amygdala is also involved in assigning emotional meaning to our memories, reward processing, and decision making.
- When electrically stimulated, animals display aggressive behavior and when it is removed, they stop displaying aggressive behavior.
The amygdala is a complex structure of cells embedded in the center of the brain, adjacent to theHippocampus(which is related to memory formation).
The amygdala is primarily involved in processing emotions and memories associated with fear. The amygdala is considered part of the limbic system in the brain and is key to processing strong emotions such as fear or joy.
Because the amygdala has connections to many other brain structures, this means it can connect to areas for processing "higher" cognitive information with systems that control "lower" functions (such as autonomic responses like breathing, touch, and sensation).
This allows the amygdala to organize physiological responses based on available cognitive information. The best known example of this is thefight or flight response.
There are two tonsils in each hemisphere of the brain and there are three known functionally distinct parts:
- The medial (middle) group of subnuclei, which has many connections to the olfactory bulb and cortex (related to olfactory functions or the sense of smell).
- The basolateral group (basolateral means below and to the side), which has a number of connections to thecerebral cortex, specifically the prefrontal cortex in the frontal lobes.
- The central and anterior (front) group of nuclei, which have many connections to the brain stem, hypothalamus, and sensory structures.
The amygdala can be stimulated when faced with a perceived threat. In a threatening situation, the amygdala sends information to other parts of the brain to prepare the body to deal with or escape from the situation.
This fight or flight response is triggered by feelings of fear,distress, aggression and anger. It is beneficial for the amygdala to function properly in order to act appropriately in threatening or stressful situations.
However, sometimes the amygdala can act too forcefully, leading toamygdala hijacking. Typically, in a stressful situation, the frontal lobes step in to override the amygdala and ensure we respond rationally.
However, when the stressful situation creates strong feelings of fear, anger, aggression, or anxiety, this can lead to illogical and irrational hyperreactive behaviors.
Essentially, the amygdala overrides the frontal lobes to take control of the stress response.
functions of the amygdala
The lesson of emotion
The amygdala plays a special role in mediating many aspects of emotional learning, as well as emotional behavior. One emotion for which the amygdala is particularly responsible is the control of fear.
To usepavlovian conditioningit can produce something called fear conditioning. This is the case when a neutral stimulus is combined with an inherently aversive unconditional stimulus.
For example, making a loud clicking noise (aversive stimulus) when a person is shown a picture of a stranger's face (neutral stimulus).
After repeated pairing of these two stimuli, neurons in the amygdala become conditioned to the change in stimuli, reflecting a conditioned fear response.
Therefore, we can expect the person in the example to be afraid of the stranger in the picture because they are conditioned to be afraid.
The literature supports the view that the amygdala has an impact on cognitive processes, such as memory formation, decision making, attention, and social behavior.
This is thought to be due to the amygdala, which projects information to the prefrontal and sensory cortex and hippocampus. Thus, the amygdala can assign emotions to these cognitive processes.
For example, we may make a decision based on our own personal emotions, or we may pay more attention to something that we believe will cause us to feel positive emotions as a result.
One area where the amygdala is most prominent is in the formation of memories, particularly emotional ones.
Because the amygdala is remarkably close and forms connections with the hippocampus (a memory structure in the brain), the two often work together to make memories more memorable.
The amygdala can associate memories with memories. The more emotional the memory, the more likely it is to be remembered.
For example, the birth of a child is often a very emotional and positive memory because it is likely to be remembered. Some emotional memories can be permanent, while memories that are mundane and have little or no emotional connection are often forgotten.
The amygdala acts as a storehouse for good and bad memories, but above all for emotional trauma. In this case, the amygdala can be harmful since these traumas are especially difficult to overcome as it is a very emotional memory.
People who have experienced emotional trauma may also find that their trauma can affect other cognitive functions as a result, since the amygdala is connected to many other regions of the brain.
Emotional memories are believed to be stored in the synapses of neurons in the brain.
There is evidence that several neuromodulators in the amygdala regulate the formation of emotional memories (Tang, Kochubey, Klintscher & Schneggenburger, 2020). Fear memories are believed to be embedded in neural connections in the amygdala.
The amygdala is the most important part of the limbic system for many emotions, including aggression.
Amygdala reactivity is a good predictor of aggression. Groves and Schlesinger (1982) found that surgical removal of the amygdala reduced aggression in previously violent individuals.
In animal studies, stimulation of the amygdala leads to aggressive behavior. Removal of the amygdala in monkeys, rats, and humans reduces aggression.
ManyNeuroimagingStudies have examined the structural and functional connectivity of the amygdala.
Regarding social behavior, it has been shown that the basolateral part of the amygdala, which sends signals to the hippocampus, is capable of modulating social behavior in a bidirectional way (Ada, Felix-Ortiz, & Tye, 2014).
Amygdala volume has also been shown to be positively correlated with the number of social contacts and the number of social groups a person belongs to (Bickart, Wright, Dautoff, Dickerson, & Barrett, 2011).
Basically, the more friends and circles of friends someone has, the bigger their amygdala.
It has been suggested that sexual orientation is related to structural differences in the amygdala. Homosexual men tend to show similar patterns in their amygdala as heterosexual women.
These two groups tend to have more extensive connections in their left amygdala.
Likewise, homosexual women tend to show similar patterns to heterosexual men and have more extensive right amygdala connections (Swaab, 2007).
Studies suggest that acute stressors and chronic stress are strongly associated with neural activity within the amygdala (Correll, Rosenkranz & Grace, 2005).
Similarly, synaptic plasticity (the ability of synapses to become stronger or weaker over time) within the amygdala is affected by stress (Vouimba, Yaniv, Diamond, & Richter-Lerin, 2004).
mental health disorders
A variety of research has shown that the amygdala, particularly on the left side, is associated with mental illness such as mental illness.social anxiety, TOC (obsessive compulsive disorder),generalized anxiety disorderand post-traumatic stress disorder (Arehart-Treichel, 2014).
People with a severe case of social phobia show significant correlations with increased amygdala response (Phan, Fitzgerald, Nathan & Tancer, 2006).
Also, those who have more pathways from the amygdala to the prefrontal cortex are more likely to experience nervousness and anxiety, as these pathways allow the frontal cortex to be flooded with more threat warnings from the amygdala.
People diagnosed with depression have been shown to have excessive hyperactivity in the left amygdala, particularly when interpreting facial emotions, primarily fearful faces (Sheline et al., 2001).
Similar results were discovered in another study involving people with PTSD. When shown images of faces with fearful expressions, their amygdala tended to show high activation (Carlson, 2012).
However, in bipolar disorder, one study found that these individuals had significantly smaller amygdala volumes than individuals without bipolar disorder (Blumberg, Kaufman, & Martin, 2005).
Regarding addiction, the basolateral amygdala has shown involvement in people who relapse in relation to drugs.
In particular, the amygdala integrates the effects of stress into drug-related memory (Wang et al., 2008). The amygdala has also been shown to influence Internet addiction.
It was found that the functional connectivity between the amygdala and the prefrontal cortex was altered in individuals with Internet addiction, thus it was concluded that this type of addiction may be associated with emotional disorders and emotion processing (Cheng & Liu, 2020).
If there is damage or differences in the structure and function of the amygdala, one or more of the following symptoms may occur:
- Difficulty forming memories, particularly those that would be emotional memories, since the amygdala and hippocampus are interconnected.
- Hyperactive fear responsehypervigilance, which leads to many situations being interpreted as a threat and a loss of control over bodily reactions.
- Emotional sensitivity.
- Anxiety associated with amygdala overactivity or little or no anxiety associated with amygdala underactivity.
- Too aggressive in hyperactivity of the amygdala.
- Overstimulation in hyperactivity of the amygdala.
- Deficits in recognizing emotions (especially fear) when the amygdala is damaged or underactive.
A famous case study of someone who had amygdala damage in both hemispheres is patient SM. SM had no apparent motor, sensory, or cognitive deficits and was able to identify a variety of facial expressions.
However, the only facial expressions he couldn't identify were faces showing fear. He could also draw pictures of any facial expression, but he could not draw a scary expression and claimed that he did not know what a scary face would look like.
When the amygdala is damaged or not fully functional, it can interfere with the acquisition and expression of fear learning. As a result, they may not learn in the Pavlovian form of classical conditioning.
This suggests that they are less vulnerable.forms phobiasand less likely an anxious person, but they may not be naturally risk averse and therefore this may affect their ability to make safe decisions.
Deficits in the amygdala can lead to anxiety disorders, addictions, depression, post-traumatic stress disorder, obsessive-compulsive disorder, and phobias.
However, there is no direct way to treat a damaged tonsil.psychotherapyand medications can help with some of the symptoms associated with mental illnesses experienced.
Deep brain stimulation has also shown promising results in relieving some of the psychological and behavioral side effects, such as hypervigilance.
About the Author
Olivia Guy-Evans received her BA in Educational Psychology from Edge Hill University in 2015. She then received her MA in Educational Psychology from the University of Bristol in 2019 Bristol for the past four years.
To reference this article:
To reference this article:
Guy-Evans, O. (2021, May 9).Function and location of the tonsil. Just psychology. www.simplypsychology.org/amygdala.html
APA style references
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Blumberg, H., Kaufmann, J. & Martin, A. (2005). Amygdala and hippocampal volumes in adolescents and adults with bipolar disorder.Yearbook of Applied Psychiatry and Mental Health, 2005, 31-32.
Carlson, N.R. (2012). behavioral physiology. Pearson Higher Education.
Cheng H and Liu J (2020). Alterations in amygdala connectivity in Internet addiction disorder. Scientific Reports, 10(1), 1-10.
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The amygdala is commonly thought to form the core of a neural system for processing fearful and threatening stimuli (4), including detection of threat and activation of appropriate fear-related behaviors in response to threatening or dangerous stimuli.What is the amygdala simple explanation? ›
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