Why we have flashbacks: the somatic marker hypothesis

ventromedialEvidently, it’s all about the ventromedial prefrontal cortex.  I had to read this sentence 3 or 4 times before I understood it, but it seems to express the entire occurrence of flashbacks very neatly.

“The ventromedial prefrontal cortex is a repository of dispositionally recorded linkages between factual knowledge and bioregulatory states. Structures in ventromedial prefrontal cortex provide the substrate for learning an association between certain classes of complex situation, on the one hand, and the type of bioregulatory state (including emotional state) usually associated with that class of situation in past individual experience.”  Bechara, et al. Emotion, decision making and the orbitofrontal cortex.

The hypothesis being described is the somatic marker hypothesis. This hypothesis specifically claims the following:

“When subjects face a situation for which some factual aspects have been previously categorized, the pertinent dispositions are activated in higher-order association cortices. This leads to the recall of pertinently associated facts which are experienced in imagetic form. At the same time, the related ventromedial prefrontal linkages are also activated, and the emotional disposition apparatus is competently activated as well. The result of those combined actions is the reconstruction of a previously learned factual–emotional set.”

So, I think that pretty much sums it up.

What’s interesting, of course, is that although having traumatic material activated in that way is something akin to torture, people who don’t do this, who have lesions in this area and aren’t able to activate associations between experiences and somatic states make terrible decisions for their lives generally. In a gambling experiment, they continue to place their money on bet that over time will lead to greater losses than gains. Even when they know that this is happening, they continue. Apparently, you need that little nip of fear in order to follow through on making a better decision.

So, while trauma memories suck, the normal tendency to recall previous experiences in the body when facing current experiences is generally a good thing.

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