It is admitted the hippocampus is necessary to the formation of new long term memories. At first, information goes back and forth between various parts of the cortex and the hippocampus. That's how a long term memory is being formed. Once it is formed the hippocampus is not necessary to retrieve the memory. It can be bypassed. The question is do we know how it is possible? How does the hippocampus (and maybe the Papez circuit) associate informations from various areas of the cortex to make one memory? Do we have a physical explanation that makes sense?