How your Memory Works:

The memory itself is thought to be stored by altering the structure of a molecule called RNA within brain cells. For a memory to be made it must enter the cell by seeing, hearing or doing something,which accounts for the three kinds of memory - visual, auditory or kinesthetic. If a memory involves all three, it will exist in a maximum number of brain cells. Thats why if you both see a telephone number, repeat it to yourself aloud and punch the numbers on the phone several times you are more likely to remember it.The brain, particulary the hippocampus region, then decides whether it's worth storing. In Alzheimer's, the hippocampus loses its ability to file memories, resulting in an inability to store new memories.

A critical question is how memories are put into storage, retrieved and connected. The key memory molecule is the neurotransmitter acetylcholine, highly concentrated in the hippocampus. People with Alzheimer's for example, show a marked deficiency of acetylcholine. Even if a memory is intact, if you dont have enough acetylcholine you can't connect one part of the memory with other parts. For example, you know the face but can't remember the name.