Amygdala: What It Is & Its Functions

The amygdala is a complex structure of cells nestled in the middle of the brain, adjacent to the hippocampus (which is associated with memory formation). It is part of the limbic system and plays a key role in processing emotions and emotional reactions.

Key Takeaways

• The amygdala in the limbic system plays a key role in how animals assess and respond to environmental threats and challenges by evaluating the emotional importance of sensory information and prompting an appropriate response.
• The main job of the amygdala is to regulate emotions, such as fear and aggression.
• The amygdala is also involved in tying emotional meaning to our memories, reward processing, and decision-making.
• When it is stimulated electrically, animals show aggressive behavior, and when it’s removed, they no longer show aggressive behavior.

What Does The Amygdala do?

The amygdala is essential for processing emotional reactions and attaching emotional significance to experiences, playing a central role in various aspects of behavior and cognition.

Emotion Regulation

The amygdala primarily regulates emotional responses, including fear, anxiety, aggression, and happiness.

It is especially prominent in controlling fear through emotional learning or fear conditioning, wherein a neutral stimulus becomes associated with an aversive event, causing conditioned fear responses.

Memory Formation

Emotionally charged memories are significantly influenced by the amygdala, which works closely with the hippocampus.

Memories involving strong emotions, such as joy or trauma, tend to be more vivid and enduring.

Emotional memories, particularly fear-based, are thought to be stored within the synapses of neurons in the amygdala.

Aggression

The amygdala plays a critical role in aggressive behavior. Stimulating the amygdala in animals leads to increased aggression, whereas removal or damage to this region often results in decreased aggression.

The reactivity of the amygdala is considered a reliable predictor of aggressive behaviors.

Fear and Anxiety

Historically labeled as the “fear center,” the amygdala initiates physiological fear responses and contributes significantly to anxiety.

It activates fight-or-flight reactions by interacting with the hypothalamus and brainstem.

Although recent research has nuanced this view, indicating the amygdala is part of a broader emotional regulation network, its role in mediating anxiety and fear remains substantial.

Social Behaviors

The amygdala also influences social interactions and relationships.

Research shows a positive correlation between the volume of the amygdala and an individual’s number of social connections, suggesting its involvement in social network processing (Bickart, Wright, Dautoff, Dickerson, & Barrett, 2011).

It modulates social behaviors through bidirectional connections with the hippocampus.

Stress Response

The amygdala is sensitive to both acute and chronic stressors. Exposure to stress affects neuronal activity and synaptic plasticity within the amygdala, indicating its pivotal role in processing stress responses.

Mental Health Disorders

Amygdala dysfunction has been linked to several mental health conditions, including social anxiety, obsessive-compulsive disorder, generalized anxiety disorder, post-traumatic stress disorder (PTSD), schizophrenia, depression, and bipolar disorder (Arehart-Treichel, 2014).

For instance, heightened amygdala activity is commonly observed in individuals with social anxiety and PTSD, while reduced amygdala volumes have been noted in those with bipolar disorder.

Addiction

The amygdala, particularly the basolateral region, significantly impacts addiction behaviors. It integrates stress responses with drug-related memories, influencing relapse likelihood.

Altered connectivity between the amygdala and prefrontal cortex has also been associated with internet addiction, emphasizing its role in emotional disturbances linked to addictive behaviors (Cheng & Liu, 2020).

Breathing Regulation

Recent findings reveal that the amygdala contributes to respiratory regulation, particularly during and after seizures (Harmata et al., 2023).

Activation or seizure spreading to specific amygdala regions can lead to prolonged apnea, indicating its critical involvement in seizure-related breathing issues.

Amygdala Hijack

The amygdala can be stimulated when faced with a perceived threat. If in a threatening situation, the amygdala will send information to other parts of the brain to prepare the body to either face the situation or to get away from it.

Emotions of fear, anxiety, aggression, and anger trigger this fight-or-flight response. It is beneficial that the amygdala is working correctly to act appropriately in threatening or stressful situations.

However, sometimes, the amygdala can act too strongly, leading to amygdala hijacking. Typically, in a stressful situation, the frontal lobes will step in to override the amygdala to ensure we respond rationally.

But, if the stressful situation causes strong feelings of anxiety, anger, aggression, or fear, this can result in illogical and irrational overreactive behaviors being displayed.

Essentially, the amygdala overrides the frontal lobes to hijack stress response control.

Amygdala’s Connections and Neuronal Circuits

The amygdala has widespread connections to various parts of the brain, allowing it to receive sensory information and influence responses. Its key connections include:

• Input from the sensory thalamus and sensory cortices (visual, auditory, somatosensory) – provides sensory information to the amygdala.
• Output to the hypothalamus and brainstem – allows emotional responses like fear and aggression.
• Bidirectional connections with the prefrontal cortex – integrates emotions, cognition, and decision-making.
• Bidirectional connections with the hippocampus – links emotions to memories.
• Output to the nucleus accumbens and ventral striatum – involved in reward processing.

There are two amygdalae in each hemisphere of the brain, and there are three known functionally distinct parts:

1. The medial (middle) group of subnuclei has many connections with the olfactory bulb and cortex (related to olfactory functions or sense of smell). It also connects with the hypothalamus for social and reproductive behaviors.
2. The basolateral group (basolateral meaning below and to the side) has several connections with the cerebral cortex, particularly the prefrontal cortex within the frontal lobes. This allows it to link sensory stimuli with emotional responses and memory formation.
3. The central and anterior (front) group of nuclei has many connections with the brain stem, hypothalamus, and sensory structures. It initiates physiological fear responses through these pathways.

What Happens If The Amygdala Is Damaged?

If there are damages or differences in amygdala structure and function, one may experience one or more of the following symptoms:

• Difficulties with forming memories, especially those which would be emotional memories, due to the amygdala and hippocampus being connected.
• Overactive fear response or hypervigilance leads to interpreting many situations as threats and losing control over physical responses.
• Emotional sensitivity.
• Feeling anxious if there is hyperactivity of the amygdala or feeling little or no anxiety if the amygdala is underactive.
• Overly aggressive if there is hyperactivity of the amygdala.
• Feeling over irritable if there is hyperactivity of the amygdala.
• Deficits in recognizing emotions (especially fear) if the amygdala is damaged or underactive.

In addition to these emotional and cognitive symptoms, conditions affecting the amygdala can also trigger physical responses:

• Sympathetic nervous system activation: Commonly known as the “fight-or-flight” response, this can lead to heightened physical arousal.
• Increased heart rate and pulse: You might notice your heart beating faster, even in non-threatening situations.
• Sweating: Excessive sweating can occur without physical exertion.
• Rapid breathing: Also known as tachypnea, this can happen suddenly and may feel overwhelming.

If you suspect that you have a condition affecting your amygdala, it’s crucial to consult a healthcare provider. They can help identify which symptoms to monitor and suggest effective management strategies.

For those uncertain about having a condition impacting their amygdala but suspecting its presence, seeking professional evaluation is wise. Healthcare professionals can conduct necessary tests to diagnose any underlying issues and offer guidance on potential treatments.

How to Soothe Your Amygdala

Calming your amygdala, the brain’s epicenter for emotions such as fear and anxiety, involves a combination of mental health strategies and lifestyle adjustments.

Here’s how you can achieve a serene state of mind:

Prioritize Mental Well-being

• Seek Professional Guidance: Consult with healthcare professionals if you frequently struggle with anxiety or panic. They offer valuable resources and support to navigate both immediate and long-term emotional challenges.
• Explore Therapeutic Options: Engage in therapies like cognitive-behavioral therapy (CBT) or mindfulness-based stress reduction (MBSR). These approaches can help reframe anxious thoughts and promote a sense of calm.

Practical Techniques to Ease Panic

• Breathing Exercises: Practice deep breathing to regulate your nervous system. Techniques like the 4-7-8 breathing method can be particularly effective during stressful moments.
• Grounding Exercises: Use grounding techniques, such as focusing on your five senses, to anchor yourself in the present and diminish overwhelming emotions.

Stress and Anxiety Management

• Adopt a Mindful Practice: Meditation and yoga are excellent for reducing stress levels and relaxing your amygdala. Apps like Headspace or Calm offer guided practices to get you started.
• Stay Active: Regular physical activity releases endorphins, which naturally combat anxiety. Whether it’s a brisk walk or a heart-pumping workout, integrate movement into your daily routine.
• Pursue Hobbies: Engage in activities you enjoy, whether it’s painting, gardening, or playing an instrument. Hobbies provide a productive distraction from anxiety and can be an outlet for expression.

If finding the right method proves challenging, professional advice can guide you toward suitable practices for your lifestyle and needs. Remember, soothing your amygdala is about finding balance and nurturing mental tranquility.

FAQs

References

Arehart-Treichel, J. (2014). Changes in Children’s Amygdala Seen After Anxiety Treatment.

Bickart, K. C., Wright, C. I., Dautoff, R. J., Dickerson, B. C., & Barrett, L. F. (2011). Amygdala volume and social network size in humans. Nature Neuroscience, 14(2), 163-164.

Blumberg, H., Kaufman, J., & Martin, A. (2005). Amygdala and Hippocampal Volumes in Adolescents and Adults With Bipolar Disorder. Year Book of Psychiatry & Applied Mental Health, 2005, 31-32.

Carlson, N. R. (2012). Physiology of behavior. Pearson Higher Ed.Cheng, H., & Liu, J. (2020). Alterations in Amygdala connectivity in internet Addiction Disorder. Scientific Reports, 10(1), 1-10.

Correll, C. M., Rosenkranz, J. A., & Grace, A. A. (2005). Chronic cold stress alters prefrontal cortical modulation of amygdala neuronal activity in rats. Biological Psychiatry, 58(5), 382-391.

Felix-Ortiz, A. C., & Tye, K. M. (2014). Amygdala inputs to the ventral hippocampus bidirectionally modulate social behavior. Journal of Neuroscience, 34(2), 586-595.

Harmata, G. I., Rhone, A. E., Kovach, C. K., Kumar, S., Mowla, M. R., Sainju, R. K., … & Dlouhy, B. J. (2023). Failure to breathe persists without air hunger or alarm following amygdala seizures. JCI insight, 8(3).

Kiehl, K. A. (2006). A cognitive neuroscience perspective on psychopathy: Evidence for paralimbic system dysfunction. Psychiatry Research, 142(2-3), 107-128.

LeDoux, J. E. (2020). Thoughtful feelings. Current Biology, 30(11), R619-R623.

Lilienfeld, S. O. (1998). Methodological advances and developments in the assessment of psychopathy. Behaviour Research & Therapy, 36, 99–125.

Maren, S. (2001). Neurobiology of Pavlovian fear conditioning. Annual review of neuroscience, 24(1), 897-931.

Phan, K. L., Fitzgerald, D. A., Nathan, P. J., & Tancer, M. E. (2006). Association between amygdala hyperactivity to harsh faces and severity of social anxiety in generalized social phobia. Biological Psychiatry, 59(5), 424-429.

Salzman, C. Daniel (2019, February 27). Amygdala. Encyclopedia Britannica. https://www.britannica.com/science/amygdala

Sethi, A., McCrory, E., Puetz, V., Hoffmann, F., Knodt, A. R., Radtke, S. R., … & Viding, E. (2018). Primary and secondary variants of psychopathy in a volunteer sample are associated with different neurocognitive mechanisms. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, 3(12), 1013-1021.

Sheline, Y. I., Barch, D. M., Donnelly, J. M., Ollinger, J. M., Snyder, A. Z., & Mintun, M. A. (2001). Increased amygdala response to masked emotional faces in depressed subjects resolves with antidepressant treatment: an fMRI study. Biological Psychiatry, 50(9), 651-658.

Swaab, D. F. (2008). Sexual orientation and its basis in brain structure and function. Proceedings of the National Academy of Sciences, 105(30), 10273-10274.

Tang, W., Kochubey, O., Kintscher, M., & Schneggenburger, R. (2020). A VTA to basal amygdala dopamine projection contributes to signal salient somatosensory events during fear learning. Journal of Neuroscience, 40(20), 3969-3980.

Vouimba, R. M., Yaniv, D., Diamond, D., & Richter‐Levin, G. (2004). Effects of inescapable stress on LTP in the amygdala versus the dentate gyrus of freely behaving rats. European Journal of Neuroscience, 19(7), 1887-1894.

Wang, X. Y., Zhao, M., Ghitza, U. E., Li, Y. Q., & Lu, L. (2008). Stress impairs reconsolidation of drug memory via glucocorticoid receptors in the basolateral amygdala. Journal of Neuroscience, 28(21), 5602-5610.

Zheng, G., Zhou, Y., Zhou, J., Liang, S., Li, X., Xu, C., Xie, G., & Liang, J. (2023). Abnormalities of the Amygdala in schizophrenia: a real world study. BMC psychiatry, 23(1), 1-9.

Further Reading

• Sah, P., Faber, E. L., Lopez de Armentia, M., & Power, J. M. J. P. R. (2003). The amygdaloid complex: anatomy and physiology. Physiological reviews, 83(3), 803-834. 
• Kim, J. E., Dager, S. R., & Lyoo, I. K. (2012). The role of the amygdala in the pathophysiology of panic disorder: evidence from neuroimaging studies. Biology of mood & anxiety disorders, 2(1), 1-17. 
• Ressler, K. J. (2010). Amygdala activity, fear, and anxiety: modulation by stress. Biological psychiatry, 67(12), 1117-1119. 
• Davis, M. (1992). The role of the amygdala in fear and anxiety. Annual review of neuroscience, 15(1), 353-375.