Bostancıklıoğlu similarly showed that optogenetic manipulation of serotonin nuclei retrieve the lost memory by closing potassium channels on the memory engram cells, raising questions about the effects of serotonin on memory engram cells and pointing to the possible interface between the amyloid‐centric hypothesis of AD and the memory engram hypothesis in order to explain memory loss in AD [116]. This evidence concerns the gene KCNA3 and Alzheimer disease.