Epigenetics Trauma can affect the individual at the genetic level. Although genes are stable, research has shown that they are not necessarily destiny. Epigenetics refers to chemical modifications that attach to DNA and have the ability to turn genes on or off, affecting their expression but not altering the underlying DNA itself (Binder, 2016). Epigenetic changes occur in response to environmental signals and experiences, such as trauma. Research has shown that Conclusion Having a basic understanding of neurobiology and the way that trauma can become embedded within biological systems is important for clinicians who wish to provide appropriate treatment methods to alleviate distress for clients who suffer from trauma. This chapter reviewed basic brain anatomy and functions, including the three-part brain and right-and-left-hemispheric organization, with the different functions of various parts of the brain in stimulus input, memory storage, and memory retrieval during traumatic stress and nonstress situations. For example, the limbic system, in particular the amygdala, becomes overstimulated during traumatic stress, and its alarm bells override the processing abilities of the hippocampus and the thinking and reflecting abilities of the prefrontal cortex. This “bottom-up” processing was contrasted with the more typical “top-down” processing that occurs throughout the day. This chapter also discussed how traumatic memory can be stored as implicit memory (as somatosensory images
traumatic experiences can act to “turn off” genes involved with the stress response system, potentially contributing to a dysfunctional or dysregulated stress response (Binder, 2016). Thus, trauma can reach down to the core blueprint of human development. Epigenetic changes are, however, flexible and dynamic, suggesting that negative consequences can be reversed with positive inputs, such as therapy (van der Kolk, 2014). and feelings) in the limbic system rather than as narrative and declarative explicit memory in the prefrontal cortex; this manner and location of traumatic memory storage has implications for effective treatment approaches. The primary systems involved in stress activation and regulation were discussed. This discussion included the HPA system, allostatic systems, and polyvagal systems, and their effect on the body and physical functioning. The concept of a window of affect tolerance was described. The clinician is cautioned to be aware of this window and assist clients in maintaining an optimum level of arousal, both within and outside of the therapeutic context. The concept of state-dependent memory, which refers to the effect that frame of mind and the individual’s physiology have on subsequent voluntary or involuntary memory retrieval, was also discussed. Finally, the complicated topics of neuroplasticity, psychoimmunology, and epigenetics rounded out this chapter on the basic neurobiology of response to trauma.
UNDERSTANDING DISSOCIATION
Dissociation is strongly associated with vulnerability to the development of posttraumatic stress disorder. People dissociate when they are in extreme pain or terrified and have no means of escape, except to leave via the mind and the spirit (van der Kolk, 2014). Dissociation is a complex topic and one of the most misunderstood aspects of trauma responses. It has been discussed as both a protective factor in the face of traumatic exposure and as a contributing factor in the development and severity of PTSD symptoms (Atchley & Bedford, 2020). It refers to a compartmentalization of experience and a splitting of awareness: Elements of the traumatic events are separated from each other in the body–mind system. As discussed in previous chapters, one of the responses of the brain to overwhelming fear and terror is to switch into an automatic response mode and ready the system for fight, flight, or freeze. While the system is being flooded with the necessary neurochemicals (such as cortisol) to perform these actions, the hyperfocus that is necessary to respond creates a narrowing of perception that eliminates distractions from the immediate task of survival. During this time, the resulting compartmentalization is a useful coping mechanism because it allows the individual to eliminate unnecessary input from the environment so that all available resources can be used to avoid an attack or perceived attack (Steele et al., 2016). Functional dissociation is a way of organizing information under extreme stress. Case Example Morgan said, “I would lie in bed at night and listen for the sound of footsteps in the hall. It was as if every cell of my body was listening acutely for my father’s footsteps. I could hear every squeak the floorboards made, and I could tell if it was my mother’s steps, my cat’s, or my father’s. I would hold my breath until the footsteps passed—unless they didn’t. Then I would try to hold my breath until he left the room, thinking that if I held perfectly still, it wasn’t really happening. That’s what I mostly remember—holding my breath and straining to listen.”
There are many stories about traumatic events (e.g., the scene of a car accident) where several people were present and each one provides a slightly, or even dramatically, different account of what happened, who was present, or the details of the event. What they remember depends in part on what aspect of the event they were focused on at the time and what was in their field of perception from their particular vantage point. Other parts of the event are, literally, not seen; therefore, they are not remembered, even though they happened. Dissociation can also be understood as a defensive response to distress, when there is more pain than the individual can tolerate. Avoidance of pain is survival based; it becomes a problem only when survival is no longer an issue, but the response continues as if it were. Dissociation changes a person’s focus and awareness in order to preserve their ability to get through a situation intact. Thus, the initial dissociation serves as an affect regulator in the presence of an overwhelming stimulus and can be a temporary solution to a problem. If the initial dissociated response becomes entrenched and therefore unprocessed, it then becomes problematic. To dissociate during a traumatic event, the person must associate to something else. To avoid feeling the pain in the body, the mind goes elsewhere. Survivors often report feeling as though they were outside of their bodies during abuse, watching the event from above in a disembodied state. In this way, they can separate mind and body and separate themselves from the pain and a full awareness of the impact of the events. Dissociation functions as a psychic anesthesia. For example, survivors say, “I counted the cracks in the ceiling, over and over again, until the abuse stopped” or “In my mind, I went outside my window where there was a nest in a tree, and I imagined myself there” or “My soul left my body at that moment.” What is intolerable for the individual to accept or hold becomes shunted off to another part of memory storage in the limbic system. There, it is encoded in sensation and emotion, rather than
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