http://www.huffingtonpost.com/steven-m-southwick/trauma-resilience_b_1881666.html
Let’s take a quick look at some genetic and biological factors that have been associated with resilience. While no one gene or gene variation explains resilience, genetic factors do play an important role in determining how an individual responds to stress and trauma. For example, DNA studies have found that polymorphisms (i.e., variations) of genes that regulate the sympathetic nervous system, the hypothalamic-pituitary-adrenal axis, and the serotonin system partially determine whether our biological response to stress is too robust, too muted, or within a range that is optimal for adaptive functioning. In addition, studies of identical twins, where one twin has been exposed to a traumatic stressor such as combat but the other twin has not, have estimated an overall heritability of posttraumatic stress disorder ranging from 32-38%. This means that genes are important but that they are only part of the story.
A host of neurobiological factors and systems have been associated with resilience including a sympathetic nervous system (i.e., epinephrine and norepinephrine) and a hypothalamic-pituitary-adrenal axis (i.e., cortisol) that respond rapidly to stress and danger but that are well regulated and shut off once the danger has passed; a dopamine reward system that continues to fuel positive emotions even during periods of chronic stress; intact hippocampi that allow us to form new memories, to differentiate between dangerous and safe environments, and help to regulate our stress response; and a highly developed prefrontal cortex that can regulate emotional and behavioral reactivity to stress by inhibiting the amygdala, which plays a central role in processing and triggering raw emotions related to the fight-flight response.Emerging scientific research has begun to show that neurobiological systems associated with resilience can be strengthened to respond more adaptively to stress. For example, research using EEG and fMRI technology has shown that mindfulness meditation and training in cognitive reappraisal can increase activation of the left prefrontal cortex. This is important because people with greater activation of the left prefrontal cortex recover more rapidly from negative emotions such as anger, disgust, and fear. University of Wisconsin researcher Richard Davidson has proposed that resilience is largely related to activation of the left prefrontal cortex and the strength of neural connections between the prefrontal cortex and the amygdala. Robust activation of the PFC inhibits the amygdala, quiets associated anxiety and fear-based emotions, and allows the PFC to facilitate rational planning and behavior.
