hyperamnesia and trauma
The ability to remember and retrieve an excessive amount of information, albeit abnormal, presents a myriad of benefits to the individual. Among these would be the reduction in misnaming acquaintances, having the ability to pass exams and recalling childhood memories that normally would have been forgotten. Despite this, this abnormal ability has become central in the experience of PTSD, or post-traumatic stress disorder yet this concept has been left relatively unexplored.
PTSD has been defined as the recurrent intrusive recollection of a traumatic event that is relived in ordinary safe situations whilst often having difficulty remembering the declarative aspects of the trauma which can be recalled in fragments. Emotional hypermnesia specifically, or the increased ability to recall emotional information, therefore is essential in the maintenance of PTSD as stimulates the same emotions as felt when experiencing the traumatic event. Animal models have been used in order to test emotional hypermnesia’s involvement in the maintenance of PTSD, with the use of rodents, inducing the effects through fear conditioning and the administration of corticosterone, the main stress hormone in rodents (Sapolsky, 1996). It was found that contextual amnesia increased the propensity to experience emotional hypermnesia after a traumatic event, yet promoting memorization of the context is suggestive of normal memory formation. The formation of memory involves both the hippocampus and the amygdala, which when there are high levels of cortisol which promotes amygdala-based fear conditioning diverting attention away from the contextual aspects.
Al Abed, A. S., Ducourneau, E. G., Bouarab, C., Sellami, A., Marighetto, A., & Desmedt, A. (2020). Preventing and treating PTSD-like memory by trauma contextualization. Nature communications, 11(1), 1-9.
Calandreau, L., Desgranges, B., Jaffard, R. & Desmedt, A. Switching from contextual to tone fear conditioning and vice versa: The key role of the glutamatergic hippocampal-lateral septal neurotransmission. Learn. Mem. 17, 440–443 (2010)
Sapolsky, R. M. Why stress is bad for your brain. Science 273, 749–750 (1996).
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