Me Know Music

What exactly happens to the knowledge that once dwelled in our brains daily after a few years of non-use? This is the great mystery I need to solve. Twice this week I have been asked to define a music theory term, and the answer was pathetic. I used to be able to spout off this kind of stuff. Where did the knowledge go? 

I've heard theories, the best was that the knowledge that filled a brain pre-children goes out with the milk. So after 11 years of nursing kids, my brain should be pretty empty. That would explain the fact that I now respond to simple questions like a cave-woman. 

The sad thing is that this very useful knowledge has been replaced by other information, like the names of every Star Wars guy that litters my living room floor. Or even better, how to make a paper water bomb. How could this info be more important than the definition of fugue? 

At this point all the Ginkgo in the world cannot help, I guess it is time to just give in. So if you ask me an intelligent question, and I look glazed over, use small words and hand gesture, and maybe I can come up with a two word answer.