Why Survivors Forget
Times of extreme stress such as traumatic events can impair how memory is stored and subsequently recalled. As a result, there may be portions of a traumatic memory that are unclear or forgotten. However, even memories with missing elements can still be vividly recalled with fragments of images and highly disturbing somatic sensations.
“Memories of physical or sexual abuse are held within portions of the brain highly sensitized to stress hormones. This can lead to strong emotions and body sensations without a well-developed ability to explain your experience with words. This process can evoke feelings of shame and self-doubt. A physiological explanation of traumatic memory can provide a foundation for increased self-acceptance and compassion.”
-Dr. Arielle Schwartz
Neuroscience of Trauma 101
The brain develops hierarchically from the bottom up and the inside out. The lowest brain centers hold our most primitive survival reactions and the upper brain centers serve a regulating and reflective purpose.
The lowest brain centers, sometimes referred to as the reptilian brain, are involved with activating defensive stress reactions. These centers reflexively respond to fearful events and stimuli with a startle response, increased heart rate, quickened breath, and increased muscle tension.
The middle area of the brain is called the limbic system which provides the neural basis for memories and emotions. Within the limbic system, the amygdala and hippocampus work in conjunction with each other for memory encoding and retrieval; however, they have very different roles. The amygdala is primarily responsible for the emotional content of memories. The amygdala acts as a warning system for the brain and body by scanning the environment for potential danger and relaying this information to the hypothalamus. The hypothalamus initiates a set of actions in the endocrine system to release hormones and engage the body’s stress related responses. Hormones and neurotransmitters initiate a cascade of responses leading to a whole-body experience of fear related sensations and emotions.
In contrast, the hippocampus is essential in long-term memory for facts. This brain structure helps the brain place specific memories within the context of thousands of other previous life experiences. This process is called consolidations and involves linking sensory components of a memory into the association cortex so that the sounds are held in the auditory context, scents in the olfactory cortex, and so forth.
The most recently evolved area of the brain is the neocortex and more specifically, a portion called the prefrontal cortex. This area allows us to be self-reflective about our emotional or somatic experience and inhibits unnecessary stress reactions.
Implicit and Explicit Memories
We have two types of memories, implicit and explicit. Implicit memories involve reptilian and limbic brain centers, specifically the amygdala. These are sometimes referred to as body memories or nonverbal memories because they are stored as motor patterns and sensations. Examples of an implicit traumatic memory might include feeling suddenly nauseous, panicked, or frozen with or without a clear understanding as to why this is happening now.
Explicit memories are long-term memories that include our knowledge of basic facts and a sequence of events including time and place. Our explicit memories rely upon the hippocampal process of consolidation. Explicit memories rely upon Broca’s area, a language area in the cortex that helps you to put your experiences into words.
Pre-Cognitive and Post-Cognitive Circuits
The brain processes incoming sensory information in two ways: precognitive and postcognitive. In the precognitive circuit, lower brain centers respond to potential danger without engaging upper brain centers. Therefore, we react without consciously reflecting on the details of the situation. From an evolutionary perspective, this is important. If you were to meet a tiger in the wild, it would be wise to run quickly rather than take the time to think about it. Only after the threatening event would we pause and reflect upon the event.
The postcognitive circuit, involves activation of the prefrontal cortex. This allows us to assess the situation while it is happening and consciously reflect on how we want to respond.
Now, we can turn our attention to the subject of traumatic memory to better understand why details may be unclear or forgotten:
- In situations of physical or sexual abuse there is a high level of threat. Therefore, the precognitive circuit is activated reducing the likelihood that we are engaging the prefrontal cortex.
- High arousal emotional and somatic experience disrupts the functioning of the hippocampus which impairs our ability to recall all of the details or maintain a sense of sequential timing of events. We might have only fragments of sensory details.
- During traumatic events, bursts of adrenaline activate the amygdala leading isolated sensory fragments to be vividly recalled. Specific sensory details such as visual images, smells, sounds, or felt experiences can be strongly imprinted and recalled.
- Broca’s area, which supports our language capacities, is also impacted traumatic stress. Thus, it becomes significantly harder to verbalize about experiences both immediately following the event and later when trying to describe the event to others.
- In situations where abuse is ongoing, the functioning of the prefrontal cortex may be altered by ongoing exposure to stress hormones. This impairs the capacity to reflect upon or regulate our emotional states.
Healing is Possible
It is important to know that you can heal from traumatic events. This is true whether they happened recently or a long time ago. It is not necessary to recall all of the details of traumatic events in order to heal and reclaim your sense of wholeness. I recommend looking for a trauma-informed therapist familiar with EMDR Therapy and Somatic Psychology to support you in your healing journey. Most importantly, find someone with whom you feel safe. Healing is possible.
Curious to learn more about the neurobiology of trauma and Healing from PTSD?
Heal and Learn with Dr. Arielle Schwartz
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About Dr. Arielle Schwartz
Dr. Arielle Schwartz is a licensed clinical psychologist, wife, and mother in Boulder, CO. She offers trainings for therapists, maintains a private practice, and has passions for the outdoors, yoga, and writing. Dr. Schwartz is the author of The Complex PTSD Workbook: A Mind-Body Approach to Regaining Emotional Control and Becoming Whole (Althea press, 2016) and co-author of EMDR Therapy and Somatic Psychology: Interventions to Enhance Embodiment in Trauma Treatment (Norton, 2018). She is the developer of Resilience-Informed Therapy which applies research on trauma recovery to form a strength-based, trauma treatment model that includes Eye Movement Desensitization and Reprocessing (EMDR), somatic (body-centered) psychology and time-tested relational psychotherapy. Like Dr. Arielle Schwartz on Facebook, follow her on Linkedin and sign up for email updates to stay up to date with all her posts.