Two particular brain regions, crucial to some kinds of memory, are the ones that decay and shrink with age and with Alzheimer’s disease: They are the hippocampus (Greek for seahorse, because its curved shape resembles that sea creature) and the medial temporal lobe (neurology-speak for the middle part of a structure just behind and above your ears). The hippocampus and medial temporal lobe are important for forming some of the kinds of explicit memory, and they’re not needed for implicit memory.
