The study on patient H.M.provides one of the first evidences that hippocampus plays a vital role in memory formation.Since then,scientists all over the world start the journey of deciphering how such brain region facilitates memorizing daily experience.However a lot of solid studies point out that hippocampus seems to work temporally: As time goes by it becomes unnecessary towards a certain memory.Many theories and studies argue that neocortex may serve to be the final location for memory storage.Recently,using optogenetic labeling tools,people have identified the existence of memory traces in one sub region of the neocortex: Retrosplenial cortex(RSC).Meanwhile using in vivo imaging on the expression of immediate early gene Egr1,our group found that when animal were trained under environment with multiple sensory cues,sparse memory traces formed in layer 2/3 neurons of multiple areas of neocortex,including visual cortex,somatosensory cortex,retrosplenial cortex and parietal cortex..However,it remains elusive whether the neuronal activation in memory-related ensemble presents the uni-or multi-sensory signal.If the signal presentation is multi-sensory integration,how can such multimodal representation be encoded and retrieved? By in vivo imaging of EGR1 expression,we tracked the population activation in visual cortical neurons and provided the direct evidences that the neuronal responses,evoked by memory recall,consist multi-sensory signal components,which includes visual and footshock related sensory signal.Furthermore,hippocampus reinstates the multi-sensory integration in the same local area,revealing an expanded integrative mechanism of memory in a single cortical unit.