I was happy to see that the researchers in this 2014 Swedish human study included emotional memories when studying the hippocampus. They demonstrated that including emotional memories wasn’t that difficult to do.
In fact, this study’s researchers deemed emotional memories to be necessary in order to properly study the hippocampus, as evidenced by this statement about the experiment’s scripts:
“The selected life events had a moderate emotional level to ensure episodic long-term memory encoding.”
It made me wonder whether there are scientific bases for why other researchers go to such lengths to avoid including emotions in human memory studies.
“The experiments revealed two important findings. First, the behavioral results showed that episodic encoding of life events requires perceiving the world from the first-person perspective centered on one’s real body, and violations of this basic condition produced impaired episodic recall, indicative of fragmented encoding.
Second, the brain imaging data demonstrated that encoding events experienced out-of body specifically impacts the activation of the left posterior hippocampus during retrieval, suggesting an impaired hippocampal binding mechanism during encoding.
These findings are fundamentally important, as they suggest a link between the ongoing perceptual experiences of the body and the world from the first-person perspective and the hippocampal episodic memory system.”
“Given the apparent requirement of a natural first-person perspective between the body and the world for intact hippocampal memory function, a dissociative out-of-body experience during an acutely stressful event could, by itself, impair the encoding mechanism and produce fragmented, spatiotemporally disorganized memories.”
http://www.pnas.org/content/111/12/4421.full “Out-of-body–induced hippocampal amnesia”