PTSD is a disorder that can develop after an individual experiences a traumatic event, usually life altering. It involves intrusive nightmares, flashbacks and memories linked to specific trauma. This leads to various other problems with cognition such as trouble sleeping due to fear, guilt or sadness, trouble concentrating and irritability. The frontal lobe of our brain normally acts to regulate amygdala function, keeping it under control when there is not a threat to devote attention to. Dr. Stevens and colleagues focused on the transition from late childhood to early adulthood, stating that the prevalence of fear related disorders dramatically increases during this period. Suggesting that this window of time in adolescent life may be critical for identifying neurobiological mechanisms that give rise to these anxiety disorders (Stevens et al., 2022).
Dr. Stevens and her collaborators explain how childhood trauma promotes functional changes in neural circuits involved in threat responses, specifically the amygdala. Through development these circuits become dysregulated, causing negative emotional reactivity. This result contributes to the emergence of anxiety disorders (Stevens et al., 2022). A total of 75 participants aged 9 were recruited through an ongoing study of child trauma exposure conducted by the Detroit Trauma Project. During fMRI scanning, participants completed a emotional faces task developed by Dr. Stevens and her colleagues. The task consisted of 24 neutral faces and 24 fearful faces, totaling 48 trials that were presented in pseudo-random order. They found a positive association between increasing amygdala response to threatening faces and fear load. Amygdala habituation to fear faces has been linked between childhood trauma and PTSD symptom severity (Stevens et al., 2022).
Juxtaposed to Dr. Stevens findings in adolescents, Dr. Korem alludes to PTSD and amygdala volume in Veterans. Two independent samples of veterans were tested through conditioning, where a (CS)visual stimulus was paired with an (US)electric-shock. Dr. Korem contrasted the activation of the amygdala to the CS+US pairing in 40 individuals, 20 of which had PTSD. Dr. Korem found that the PTSD group portrayed a reduction in amygdala reactivity (Korem et al., 2022). He concluded that the “all or none” reaction can be observed in individuals with PTSD due to lower amygdala reactivity to pain.Veterans were given fMRI brain scans to look at structural changes in the brain. These tests demonstrated that PTSD diagnosis was associated with a smaller volume in the left and right amygdala.
Additionally, the left hippocampus volume was decreased in PTSD patients, although the right hippocampal volume was unaffected. Supporting that PTSD induced changes in the limbic system, specifically the amygdala in this experiment. A meta analysis showed increased hyper activation of the amygdala, which may reflect an exaggerated response of fear circuitry. This may explain PTSD symptoms, such as hypervigilance and hyperarousal that patients often report(Korem et al.,).
In conclusion, the amygdala is the key that controls our emotional center. The amygdala is implicated in how we perceive and interpret fear, social behavior and emotional processing. Dysfunctions in the amygdala have been linked to severe anxiety disorders, depression and PTSD. Attempting to understand this almond-shaped structure buried deep in the temporal lobe could lead to ground breaking discoveries on the human condition.
References:
Korem, Nachshon. “Emotional Numbing in PTSD Is Associated with Lower Amygdala Reactivity to Pain.” Neuropsychopharmacology, Aug. 2022
Stevens, Jennifer. “Anxiety, Fear Extinction, and October-December 2022: 1 © the Author(s ...” Anxiety, Fear Extinction, and Threat-Related Amygdala Reactivity in Children Exposed to Urban Trauma, Dec. 2022,
PTSD, National Center for. "VA.gov: Veterans Affairs." Home, 15 Aug. 2013, http://www.ptsd.va.gov/
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