Memory
There isn't any one single center for memory on our brain; memory is despersed.
Brain cells that fire together during an experience can form permanent connections
Those connections let the same network of brain cells re-fire later on, which we experience as memory.
"Fire together - wire together"
Any trigger - a smell, a word, a visual association - and you are in your memories.
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"Remembering is reliving"
A trigger reactivates a network of neurons, wired together in the course of registering an event, allowing us to experoence the event anew.
Knowledge derives from connections and associations. So, the optimal strategy for learning involves making meaningful associations among topics,
once more: wired together - fired together.