This 2014 UK human study of the CA3 region of the hippocampus found:

“Individual differences in subjective mnemonic experience can be accurately predicted from measurable differences in the anatomy and neural coding of hippocampal region CA3.”

I emailed the authors as follows:

“I read the “CA3 size predicts the precision of memory recall” study, and I wondered how it could be used to help people.

I am not a scientist; I am a software developer by trade. I read the abstracts of each new issue of PNAS with an eye to how studies can help people, which I think is an implied reason to publicly fund research.

The study’s supporting information reveals that the participants scored no emotional involvement with the tasks’ memories. This variable thus did not influence the finding that the contexts of participants’ memories were not a factor.

Could it be that the study’s findings apply to only non-emotional memories, and that context could be a factor in memories that involve emotions?

Given the large role of the hippocampus in our emotional memories, would it not have been realistic to include emotional content in the study? Was it a design decision to not involve the participants’ emotions?

The study found that memory retrieval confusion increased with a participant’s smaller CA3 size. We know from studies such as http://www.pnas.org/content/109/9/E563.full “Childhood maltreatment is associated with reduced volume in the hippocampal subfields CA3, dentate gyrus, and subiculum” and its references that emotional experiences influence CA3 anatomy.

Could it be that the study’s participants were not all sampled from the same brain population?”

http://www.pnas.org/content/111/29/10720.full “CA3 size predicts the precision of memory recall”