The Body Keeps the Score Part 2: This Is Your Brain on Trauma (Chs 4-6) Summary & Analysis

Chapter 4: Running for Your Life: The Anatomy of Survival

Chapter 4 describes the organization of the brain. The base of the brain system is the reptilian brain, which is responsible for the basic functions of life, such as breathing, sleeping, and eating. Above this is the limbic system, or mammalian brain, which deals in emotions, survival, and social skills. Together, these two parts compose the emotional brain, which guides instincts and preferences, and protects from danger. Above them is the rational brain, a logical center that allows learning, understanding, and organizing. Certain areas within the brain are also responsible for different tasks. The thalamus, or the “cook,” as van der Kolk calls it, receives sensory inputs and translates them into full experiences before passing them on to the amygdala, or the “smoke detector,” and the medial prefrontal cortex, or the “watchtower.” The amygdala is responsible for quickly sensing threats and activating a stress response via the autonomic nervous system (ANS). The medial prefrontal cortex is responsible for judging the true danger of a threat, and can abort the stress response if necessary. However, in traumatized individuals, the amygdala may be inaccurate and overactive, making it much more difficult for the medial prefrontal cortex to effectively function.

Stan and Ute Lawrence, two patients who had been involved in an 87-car pile-up, showed the results of different parts of the brain going offline during a traumatic event. Stan, who experienced a flashback when reading a script of the car accident, showed activation in his amygdala and deactivation in his left dorsolateral prefrontal cortex, which allows the brain to make sense of events in time, and his thalamus. Ute, on the other hand, experienced depersonalization, in which she simply froze and numbed her emotions. Her scan showed that nearly all parts of her brain blanked out during the reading of her traumatic script.

Chapter 5: Body-Brain Connections

This chapter details the connection between the body and the mind. This connection mainly comes in the form of ANS, which has two branches: the sympathetic (SNS) and the parasympathetic (PNS). The SNS is responsible for the fight or flight response, preparing the body to either defend itself from a threat or run. The PNS then returns the body to equilibrium and aids in rest and recuperation. In 1994, Stephen Porges built on this understanding of the nervous system with Polyvagal Theory, which involves three fundamental physiological states governed by the level of safety. The first is social engagement, in which people under threat turn to others for safety or aid. Failing that, the second state is fight or flight, and, failing that, the third state is freeze or collapse, in which a person simply shuts down and tries to preserve energy.

Chapter 6: Losing Your Body, Losing Your Self

Chapter 6 discusses the disconnection between mind and body that traumatized individuals often experience. Sherry, a survivor of emotional abuse and neglect as a child and rape as an adult, illustrates this. Sherry engaged in skin-picking to feel something, and was recommended for massage therapy, during which she was unable to determine the therapist’s location by touch alone. Other patients also reported being unable to feel entire areas of their bodies. A study by Ruth Lanius further confirmed that traumatized individuals lacked activation in the midline area of the brain, which is responsible for sensory self-awareness. This disconnection is can affect both the physical and mental sense of self. Because of this, trauma survivors often experience a lack of agency (control over one’s life), alexithymia (an inability to identify feelings with words), and depersonalization (entirely losing one’s sense of self).

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