Ramirez

Creating a False Memory in the Hippocampus

   This article was very interesting, but I don't fully believe that they created or  measured false memories. False memories the way I define it are memories that never occurred in real life. In these mice this was not the case. They were actually shocked in context B. The results of movement behaviors upon the second exposure to context A with light activation of the cells in the DG from previous exposure to context A can be explained by activating these cells during context B (fear condition). When these cells were activated and put back into context A, mice did not have false memories but were simply remembering the shocks from previous fear trials. Although you could wonder why motor behavior did not appear when stimulated under context C conditions, a potential explanation is that cells that were stimulated did not line up with the visual cues that the mouse experienced in context A.  You also could wonder why no stimulation in context A was not associated with significant movement. This could be explained by insufficient activation in these cells to produce enough of the feared memory to a level that triggered a significant fear response. When they activate these cells they might be producing excessive activation, resulting in intensification of the feared memory and subsequently more movement. In my opinion, the researchers did not create a false memory, but instead generalized the retrieval of memory of context B to cells that were associated with context A and intensifying the memory with the technique they used (optogenetics). However, I think that this article strengthens their previous research that cells in the DG are associated with contextual memories. This research potentially could have applications to PTSD, a disorder where people can be triggered of past traumas in a setting that is different from the one where trauma occurred. So I would like to see more studies of the role of DG in contextual memories in subjects that present with PTSD symptoms.