Neurobiology of traumatic memory
Much of the criticism surrounding the idea of recovered memory is that the theory cannot be grounded in scientific or neurological evidence. The following studies address potential neurobiological bases of traumatic memory and symptoms thereof.
Bremner, J. D., Krystal, J. H., Charney, D. S., & Southwick, S. M. (1996). Neural mechanisms in dissociative amnesia for childhood abuse: Relevance to the current controversy surrounding the “false memory syndrome.” The American Journal of Psychiatry, 153, 71-82. (Department of Psychiatry, Yale University School of Medicine, New Haven, CT.)
Abstract: OBJECTIVE: There is considerable controversy about delayed recall of childhood abuse. Some authors have claimed that there is a “false memory syndrome,” in which therapists suggest to patients events that never actually occurred. These authors point to findings that suggest that memory traces are susceptible to modification. The purpose of this paper is to review the literature on the potential vulnerability of memory traces to modification and on the effects of stress on the neurobiology of memory. METHOD: The authors review findings on mechanisms involved in normal memory function, effects of stress on memory in normal persons, children’s memory of stressful events, and alterations of memory function in psychiatric disorders. The effects of stress on specific brain regions and brain chemistry are also examined. RESULTS: Neuropeptides and neurotransmitters released during stress can modulate memory function, acting at the level of the hippocampus, amygdala, and other brain regions involved in memory. Such release may interfere with the laying down of memory traces for incidents of childhood abuse. Also, childhood abuse may result in long-term alterations in the function of these neuromodulators. CONCLUSIONS: John Nemiah pointed out several years ago that alterations in memory in the form of dissociative amnesia are an important part of exposure to traumatic stressors, such as childhood abuse. The studies reviewed here show that extreme stress has long-term effects on memory. These findings may provide a model for understanding the mechanisms involved in dissociative amnesia, as well as a rationale for phenomena such as delayed recall of childhood abuse.
Joseph, R. (1999, August). The neurology of traumatic “dissociative” amnesia: commentary and literature review. Child Abuse & Neglect, 23(8), 715-727. (Brain Research Laboratory, San Jose, CA.)
Abstract: BACKGROUND: The relationship between traumatic emotional stress, hippocampal injury, memory loss, and traumatic (“dissociative”) amnesia was examined. METHOD: A survey of the research on emotional trauma, learning, memory loss, glucosteroid stress hormones, and the hippocampus was conducted, and animal and human studies were reviewed. RESULTS: It is well documented and has been experimentally demonstrated in animals and humans that prolonged and high levels of stress, fear, and arousal commonly induce learning deficits and memory loss ranging from the minimal to the profound. As stress and arousal levels dramatically increase, learning and memory deteriorate in accordance with the classic inverse U-shaped curve. These memory deficits are due to disturbances in hippocampal activation and arousal, and the corticosteroid secretion which can suppress neural activity associated with learning and memory and induce hippocampal atrophy. Risk and predisposing factors include a history of previous emotional trauma or neurological injury involving the temporal lobe and hippocampus, the repetitive and prolonged nature of the trauma, and age and individual differences in baseline arousal and level of cortisol. CONCLUSIONS: Although some victims may be unable to forget, amnesia or partial memory loss is not uncommon following severe stress and emotional trauma. Even well publicized national traumas may induce significant forgetting. Memory loss is a consequence of glucosteroids and stress-induced disturbances involving the hippocampus, a structure which normally plays an important role in the storage of various events in long-term memory.
Zola, S. M. (1997, Summer). The neurobiology of recovery memory. The Journal of Neuropsychiatry and Clinical Neurosciences, 9(3), 449-459. (San Diego Veterans Affairs Medical Center, San Diego, CA.)
Abstract: The so-called recovery memory syndrome–reports by adults of recovered memories of childhood sexual abuse and trauma that were allegedly “repressed” for many years–has become an important issue in the field of mental health. In particular, there is debate about the credibility of recovered memories. The author describes findings in several fields of brain science about the way memory works and how memory is organized in the brain. These findings clarify aspects of normal memory function and the process of memory distortion, and they provide a neurobiological perspective from which to approach the topic of recovered memory.