I suggest listening to this episode of The Sunday Session from The Brewing Network with Dr. Charles Bamforth where he discusses this topic in great depth.
I'm listening to Dr. Charles Bamforth's "Brewmaster's Art: The History and Science of Beer Making" on audio book during my long commutes. It's fascinating, and he's an excellent writer and speaker. I highly recommend it. One of the lectures is on head, foam and lacing.