making and learning from mistakes. The lower part of the palm corresponds to the lower brainstem. Deep inside the closed fist, where the thumb is encased, is the limbic system, where the amygdala and the hippocampus are located. The cerebellum corresponds to the back of the hand, near the wrist. Notice that Right Brain/Left Brain Although the brain is essentially made up of three large systems—the brainstem, the limbic system, and the cortex— it also has an important two-sided nature. Broadly, and by no means exclusively, the left hemisphere is more activated during linear, mathematical, concrete tasks, and the right side becomes more activated during creative and intuitive endeavors. The two hemispheres are connected by the corpus callosum, which communicates information between the right and left The Effects of Trauma on Affect Regulation The ability to regulate affective states becomes severely compromised during and following trauma and may become chronically dysregulated if posttraumatic stress disorder (PTSD) develops. All persons have an optimal arousal range (Ogden & Fisher, 2015), also known as the window of tolerance (see Figure 4-2; Gene-Cos et al., 2016). This range allows the system to process emotions and arousal at various intensities, without disruption in the system’s functioning (Gene-Cos et al., 2016). Activation of arousal and affect can range from high to low and still remain within one’s tolerance zone. With the introduction of trauma, the ability to remain within the tolerance zone is severely compromised. Poor tolerance for any arousal is a common characteristic of traumatized individuals. The middle zone (or window of tolerance) represents a person’s optimum arousal zone; any affect that falls above or below these lines cannot be properly contained or processed. Hyperarousal (affect at the top level of the zone) can lead to the intrusive cluster of symptoms, whereas hypoarousal (affect at the bottom of the zone) can lead to dissociative and numbing symptoms. When the window of tolerance is exceeded, the higher levels of processing abilities are compromised and replaced by the lower-level brain functions of reflexive, sensorimotor responses, which are mediated by the brainstem and limbic system (Ogden & Fisher, 2015). Brain Structures Related to Affect Regulation Three brain structures are central to the regulation of affect and involved in the processing of trauma: The amygdala, the hippocampus, and the prefrontal cortex (Henigsberg et al., 2019). The centrally located limbic system is thought to mediate and regulate emotion, motivation, application of meaning, and processing of social experiences. Several of the limbic centers, such as the amygdala and the hippocampus, come into play with either over- or underactivation during traumatic events and are also activated during the dream state (van der Kolk, 2014). This dream-state activation is relevant in the context of posttraumatic nightmares and the dreamwork interventions that can be employed to alleviate them. The function of the amygdala is to process, interpret, and integrate emotional memory. It compares past templates in the brain to determine the course of action (i.e., fight, flight, or freeze) and is involved in the appraisal and conditioning of fear responses. It becomes active during and while remembering a Bottom-Up/Top-Down Processing The various brain structures communicate in two significant ways. The “human brain has developed from the inside out,” starting with the primitive brain (i.e., the brainstem) responsible for basic functioning (e.g., breathing; Field et al., 2015, p. 208). After that, there is the limbic system, which coordinates emotion, reactivity,
the orbitofrontal cortex (the two fingernails) is directly in front of the limbic system, thus forming a link between the limbic system and other parts of the brain. For this reason, the orbitofrontal cortex may be deeply involved in feelings and memory and, importantly, attachment (Siegel, 2012). hemispheres, and is important for information processing. Put simply (and with the caveat that the situation is not so simple), the left brain is the naming, or linear, brain and the right brain is the intuitive, or creative, brain. This division of functions may further explain the efficacy of eye movement desensitization and reprocessing (EMDR), which employs bilateral stimulation during reprocessing exercises (Schore, 2019b).
Figure 4-2: Window of Tolerance
Note. Adapted from Ogden, P., Minton, K., & Pain, C. (2006). Trauma and the body: A sensorimotor approach to psychotherapy. W. W. Norton & Company.
traumatic event. The amygdala is the alarm bell or accelerator of the limbic system. The hippocampus is responsible for memory of facts and events. It is involved in the verbal mediation of narrative and autobiographical memory (how you know who you are and that you were in a specific place). It gives time and space context to an event. When the hippocampus is successfully processing, it recognizes a beginning, a middle, and an ending to an event and a sense of what happened first, what happened next, and so on. In contrast to the amygdala, or accelerator, the hippocampus is the brake of the limbic system. The prefrontal cortex is the last part of the brain to develop (the adult thinking brain), and it is responsible for reasoning and judgment. The left hemisphere of the prefrontal cortex is involved in sequential logic (understanding what happens next), and the right hemisphere is involved in holistic and spatial logic (the overall gestalt of an experience and where things are located in space). and reward behaviors essential for survival (Field et al., 2015). Finally, the distinctly human portion of the brain, the prefrontal cortex, is responsible for executive functioning (e.g., thoughts, planning, and regulatory control; Field et al., 2015).
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