I’ve often wondered (until I actually went and found out) why it was that whenever a hero lost his memory, his ninja training remained fully intact, as well as his car racing abilities and his perfect tomato slicing skills. (Think Jason Bourne)
Well, here is the answer:
Our long term memories are divided into two big parts, namely declarative and non-declarative memory.
Declarative memory is basically a database of facts and information. Names, places, events etc. To recall declarative memory, we have to think consciously about it.
For interest’s (and length’s) sake, declarative memory is further divided into semantic and episodic memory. Semantic memory is straight facts and events, such as, what the name of your country is. Episodic memory deals with events that are directly related to time. I.e. what you were doing when you heard about the tsunami in Japan.
Which brings us to non-declarative memory. This is the memory that deals with motor-skills and actions. For example, how to speak. You might have heard of muscle memory before. It’s when you can’t consciously remember how to do something, but your body still knows how. Say, if you haven’t driven a car in a while, and you get back behind the wheel, you’ll take a few moments to figure it out, but the position and circumstances in which you find yourself will allow your muscles to ‘remember’ what to do.
Back to our ninja hero who lost his memory. It is entirely possible (perhaps even likely, I don’t know) for a patient to lose only his declarative memory. Therefore, all his motor skills and muscle memory of how to do things will remain untouched and still ready to be used in case of emergency.