How do you cause amnesia?

I have seen in movies people forget everything about themselves, yet still remember things like math, and how to talk... how would this actually happen where only the information about their life, like their name, their age, friends, family, job, things like that... how or what would this be caused by? be specificHow do you cause amnesia?
Check these sites. Hope they work! =]

http://en.wikipedia.org/wiki/Amnesia

http://www.athealth.com/Consumer/disorders/Amnesia.htmlHow do you cause amnesia?
There are different types of memory, for example procedural memory (i.e. automated skills) and declarative memory (personal episodes or abstract facts), and often only one type is impaired in amnsia. For example, a person may forget the details of personal identity, but still retain a learned skill such as the ability to play the piano.

harcourt math

campers