In people with post-traumatic stress disorder, the fact that traumatic memories resurface often manifests itself as intrusions that differ profoundly from the processing of normal negative memories. “These characteristics have fueled theories that speculate about a unique cognitive state linked to traumatic memories. However, to date, there is little empirical evidence to support this view,” said the researchers from Yale University. They therefore conducted a study to determine whether memories linked to traumatic events in patients affected by post-traumatic stress disorder are “an alternative cognitive entity” that deviates from normal memory.
3 types of autobiographical memories
Table of Contents
The scientists focused on the hippocampus and posterior cingulate cortex to find out whether these two brain regions differentiate traumatic memories from sad events. As a reminder, post-traumatic stress disorder is linked to structural abnormalities (mainly a reduction in volume) in the hippocampus. As for the posterior cingulate cortex, it is heavily involved in understanding narratives, autobiographical processing, and, in particular, images of emotional memories.
For the research, they recruited 28 people diagnosed with post-traumatic stress disorder. To generate stimuli based on the participants’ individual autobiographical memories, the team used an image development procedure. The volunteers developed three types of autobiographical memories: those associated with their post-traumatic stress disorder (e.g. sexual assault, domestic violence), sad but non-traumatic memories (e.g. the death of a family member or a pet), and a peaceful positive event (e.g. memorable outdoor activities).
The adults were then subjected to autobiographical memory reactivation, listening to narratives of approximately 120 seconds, narrated by one of the researchers, describing their memories while undergoing an MRI scan.
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The brain processes traumatic memories differently
According to the results, published in the journal Nature Neuroscience, in the hippocampus, sad memories provoked similar neuronal representations in the participants. On the other hand, thematically similar traumatic autobiographical memories were not represented in the same way in people suffering from post-traumatic stress disorder. Another finding was that the severity of individual symptoms modulated the representation of traumatic stories in the posterior cingulate cortex.
“Our data show that the brain does not process traumatic memories as normal memories, or even as memories at all. We observed that brain regions known to be involved in memory are not activated when a traumatic experience is recalled. This finding provides a neuronal target,” concluded Daniela Schiller, co-author of the study, in a press release.
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Final Thoughts
The results of this study are opening the door to therapies that could be way more effective than what we have today. What’s promising is the idea of making treatments to fit each person’s unique brain makeup. We’re not just talking about managing PTSD symptoms better; we’re stepping into an era where we might actually overcome them.
References
Perl, O., Duek, O., Kulkarni, K.R. et al. Neural patterns differentiate traumatic from sad autobiographical memories in PTSD. Nat Neurosci 26, 2226–2236 (2023). https://doi.org/10.1038/s41593-023-01483-5
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