A: FROM MENTOR LESLIE WAITE IN CA
Hi Yeseul;
Oooh, a "Men in Black" Question! FLASH! You're memory of the aliens
is gone! Carry on with your life ! :)

We are learning a lot about memory and how it works, which parts of
the brain are involved, etc. We know from MRI studies on memory as
well as from unfortunate accidents in which people permanently lose
their memories, that certain parts of the brain are where memories
are "stored". We also know which parts of the brain hold long-term as
opposed to short term memory. But we do not currently know how to
erase specific memories from someone's brain. And even if you wanted
to erase all of someone's memory, you would pretty much need to do
surgery to destroy or remove a part of their brain, so this is
definitely not something to be done on a mass scale like in the
movies.
If you want to read in more detail about memory and how it works,
look at this article from Slate:

http://slate.msn.com/id/2097502

It talks about the movie "Eternal Sunshine of the Spotless Mind" and
the idea that you could erase the memory of a specific person from
your brain.

The article also has a link to hear the story on NPR if you prefer.