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Traumatic memories ‘trigger distinct brain activity’

People with PTSD show significant difference in brain activity when recalling general memories rather than trauma



Recollections of traumatic experiences trigger distinct brain activity which is very different from general recollections of events, a new study reveals. 

Research reveals that the brain activity triggered by recollections of trauma in people with PTSD is in fact markedly different from that which occurs when remembering sad or neutral life experiences.

It is known that people who have lived through traumatic events – such as sexual assault, domestic abuse or violence – can experience PTSD and with it anxiety and flashbacks. 

But the brain process behind that has not been known until now, through a new study from Yale University and Icahn School of Medicine at Mount Sinai. 

The research involved 28 different patients diagnosed with PTSD and found that brain patterns were consistent across all individuals when they recalled their more typical life experiences. 

But when reminded of traumatic events from their past, neural responses differed significantly among the individuals.

“When people recall sad or neutral events from their past experience, the brain exhibits highly synchronous activity among all PTSD patients,” said Ilan Harpaz-Rotem, professor of psychiatry and psychology at Yale and co-senior author of the paper. 

“However, when presented with stories of their own traumatic experiences, brain activity was highly individualised, fragmented, and disorganised.

“They are not like memories at all.”

For the study, the researchers asked each of the 28 participants a range of questions, which pertained to their traumatic experiences, events in their lives that caused sadness (such as the death of a family member), and moments when they felt relaxed. 

Each person’s story was written down and then read back to them while they underwent fMRI scans, which are used to map brain activity based on blood flow.

The researchers found that activity in the hippocampus — the area of the brain that forms memories of our experiences — followed similar patterns of activity among all subjects when they were reminded of sad or relaxing experiences from their lives, suggesting typical normal memory formation.

But when stories about their traumatic experiences were read back to them, the similarities in hippocampal activity among the group members disappeared. 

Instead, the hippocampus of each subject exhibited highly individualised and fragmented activity, unlike the more synchronous patterns of brain activity during normal memory formation.

The results could explain why PTSD patients have difficulty recalling traumatic experiences in a coherent way and hints at why these past experiences can trigger disabling symptoms, the researchers say.

These insights may help psychotherapists guide PTSD patients to develop narratives about their experiences which may help them eliminate the sense of immediate threat caused by their trauma, Dr Harpaz-Rotem said.