demonstrated that memories are preserved in the form of

At the cellular level, Eric Kandel, in a Nobel-winning series of studies, demonstrated that memories are preserved in the form of strengthened connections between neurons. Training regimes, he showed, whether conducted on intact, living, learning animals, or by electrically prodding neurons in a dish, create such beefed-up connections. And, as Ebbinghaus first observed, training (or rehearsal, or study) with extra time scheduled in between led these connections to be longer-lasting. This is a fact that holds true throughout the animal kingdom, from sea slugs to mammals.