“The brain’s memory systems (are) balanced on a knife’s edge. Too much spread of activity leads to confused recall, while too little causes no recall” (Connectome, pg. 72).

According to Seung, to prevent the former, there needs to be a high threshold for neuronal activation: in other words, multiple “triggers” are needed for recalling one memory (which then also makes recall harder/more selective).

I wondered about the idea of a “balance” between over- and under-activation in terms of PTSD – especially in terms of flashbacks.

Studies have found that the amygdalas and the right-side anterior and posterior regions of the brains of people with PTSD become overly active when those people are exposed to “triggering” stimuli. (The amygdala is related to emotional memory, so this makes sense, and according to the second study, significant right-hemisphere activation plays a role in anxiety disorders in general.) The researchers in the second study found that CBT reduces the over-activity of the right anterior region, and found that a reduction in PTSD symptoms was associated with that.

So it is clear that there is an unusually high amount of neuronal activation in PTSD flashbacks. But is that because the “threshold” Seung discusses is over-reached, or because somehow, that threshold has been lowered? And are multiple smaller triggers needed to produce a flashback, or can certain singular things (like things associated with traumatic events) somehow be stronger triggers than others?

One thought on “Triggers

  1. Lowered by the trauma? Could connectomes account for why some develop PTSD while others do not in the face of similar traumatic experiences?


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