This simplistic representation of the brain hierarchy is integral to understanding and treating trauma. Typically, humans process information from the top down; that is, the higher brain (prefrontal cortex) receives information from the environment, processes and appraises that information, and then sends signals to the lower parts of the brain about how to react to the stimuli (Field et al., 2015). When faced with threats or traumas, the brain shifts into survival mode, relying on the more primitive, reactive regions to engage the fight-or-flight response, in what is termed bottom-up processing (Field et al., 2015). It is important that holistic, integrative trauma treatments target both top-down and bottom-up systems. Research suggests that trauma can result in decreased volume in the prefrontal cortex, diminishing an individual’s inhibitory control of the lower brain and resulting in more reactive and less thoughtful or regulated responses, such as aggression (Lu et al., 2019). Professionals Affect Regulation and Neurocircuitry The ability to tolerate and regulate emotional affect is crucial to being able to mitigate the effects of trauma and not be consumed by them. With the hippocampus and the prefrontal cortex shut down during traumatic events, and the overactivation of the alarm signals from the amygdala, strong affect cannot be Optimum Window of Tolerance Thinking and behavior can become disrupted if the state of arousal moves outside of the window of tolerance, also known as the optimal arousal range, which is a description of how the person is calibrated with respect to affect. The window of tolerance refers to the range in which emotions are well tolerated and can be further understood in relation to the activation of the autonomic nervous system. Too much activation in the autonomic nervous system causes the sympathetic nervous system to speed up, resulting in increases in heart rate and respiration or a pounding feeling in the head. At the other extreme, too much activation of the parasympathetic nervous system leads to the body’s attempts to conserve energy, which manifests as a numbing or shutting down within the mind (Siegel, 2012). In this case, the sympathetic nervous system is the accelerator, and the parasympathetic nervous system is the brake. All individuals have a window of tolerance that is partially determined by inborn temperament and characteristics but that can also be directly affected by their experiential history. A person who can generally respond within that window is able to navigate the ups and downs of daily life without loss of functionality. When a traumatic event occurs, a temporary perceived threats and traumas. In instances of chronic trauma, one of those systems, the hypothalamic–pituitary–adrenal (HPA) axis, can become dysregulated (Holochwost, 2021). The HPA axis (see Figure 4-3) is the anatomical pathway in the brain that is activated in response to stress. When activated by other brain areas that detect threatening situations, the HPA axis sets off a coordinated cascade of hormones and biochemicals (e.g., adrenocorticotropic hormone [ACTH]) that help facilitate the human stress response system, including the release of adrenaline and the stress hormone cortisol. Cortisol is involved in converting protein into glucose, making fat available for energy needed for fight or flight, increasing blood flow to enhance the ability to react physically and accentuate senses, and stimulating other types of behavioral responsiveness. In this way, cortisol’s effects on the brain cause behavioral changes. In this cascade, one system starts the response and each system sends a subsequent signal to the next, engaging adaptive physiological responses, with the final message acting to send feedback to turn the response off when the danger subsides (i.e., the cortisol sends a message to the hippocampus to turn off the HPA response when it is no longer needed).
should recognize that the prefrontal cortex may be bypassed in these individuals in deference to their more reactive brain structures. Interventions that attempt to build up self-regulation through regulatory skills and strategies may be required. Alternatively, trauma can cause impairments to structures in the limbic system (the emotional brain), which might contribute to more reactive and emotional responses or dulled responses that are not as reactive as they should be (Holochwost, 2021). In these instances, mind–body approaches that help attune clients to their deeper physiological experiences are essential. Increased emphasis is being placed on somatic interventions that use sensory awareness to increase emotion regulation and integration from a “bottom-up” perspective that more “top- down” cognitive or exposure interventions may miss (Grabbe & Miller-Karas, 2018). modulated by cognitive supports from the thinking brain during, or following, the trauma. If the brain is not able to re-regulate itself and engage the mediating structures of the hippocampus and the cortex, the survivor is more likely to develop PTSD (Jaffee & Christian, 2014). dysregulation is needed to be able to respond to the threat (to fight, freeze, or flee from impending danger). However, a repeated pattern of neural activation (i.e., repeated traumatic events that become imprinted in the neurocircuitry of the brain) causes these states of chronic over- or underresponse to become ingrained, as if they were personality traits, which has profound implications for understanding, assessing, and treating troubled and traumatized individuals. An individual who is frequently operating outside of the optimum window of tolerance is responding to the world in ways that are either too intense, such as with anxiety or hypervigilance, or overly passive, numbed, or dissociated. The traumatized person may typically reside either above or below this optimum state of arousal or may swing wildly between the two states. The goal is for the individual’s responses to remain within the window of tolerance, both in daily life and in the therapy room. Treatment approaches must include precautions that prevent exceeding the window of tolerance to prevent retraumatization of the client.
Hypothalamic–Pituitary–Adrenal Dysregulation and the Stress Response Multiple biological systems are engaged in response to
Figure 4-3. Hypothalamic–Pituitary–Adrenal Axis
Note: ACTH = adrenocorticotropic hormone. From Western Schools, © 2018.
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