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Thanks to our memory, we can learn from the past and react appro­pria­tely to new situa­tions. Our memory is the­r­e­fore based on a cer­tain sta­bi­lity and dyna­mism. Howe­ver, the exact neu­ral mecha­nisms behind this have remained a mys­tery. But thanks to recent rese­arch in the hip­po­cam­pus of mice, we are now begin­ning to gain deeper insights. Accor­ding to this rese­arch, the brain crea­tes three copies for a sin­gle memory.

What we alre­ady knew: When we remem­ber, i.e., retrieve cer­tain memory con­tents, the same neu­ro­nal pat­terns are acti­va­ted that were active during enco­ding. In par­ti­cu­lar, the focus was on dis­crete popu­la­ti­ons of neu­rons that emerge at dif­fe­rent points in embryo­nic deve­lo­p­ment-and neu­rons of the same age have simi­lar pro­per­ties. The rese­ar­chers sub­jec­ted mice to a con­di­tio­ning para­digm in which the ani­mals lear­ned to asso­ciate an initi­ally neu­tral event with a fear­ful sti­mu­lus. The rese­ar­chers used cal­cium ima­ging to mea­sure cell signals and opto­ge­ne­tic methods to mani­pu­late cell acti­vity.