Memory is a complex thing and has a number of explanations. One of these is that the brain has a multi-store memory. This is made up of the following:
Sensory store: This stores information about our sensual perceptions i.e. taste, sound, sight, touch and smell. This information is stored for very short periods of time and will disappear once it has stopped being helpful.
Short-term store: This picks up information to be used in the short term. It is quite small and can only hold up to seven bits of information at any one time. It is held in the brain for perhaps a minute and will be nudged out by any new incoming information. This is our working memory and helps us to perform practical tasks. This is the reason why post codes and vehicle registration numbers, for example, never exceed seven characters.
Long-term store: The brain can store huge amounts of information, much of which will stay there for a lifetime.
——————————————————
Brain damage
So far we have talked about the way memory works, but this is assuming the brain is in working order. A part of the brain concerned with long-term memory is the hippocampus. This is one of the first parts of the brain to suffer damage when an individual suffers from Alzheimer’s disease. An individual unable to remember events leading up to the damage is suffering from retrograde amnesia. An individual unable to learn new information after the damage is suffering from anterograde amnesia.