Originally Posted by
poopdeville
Supposedly, that is exactly how genjutsu work. You "pump" chakra into their brain/nervous system and take control of it by swamping their chakra out. If the victim has enough chakra, he can mold a bunch and override the override. In fact, that is why Killer Bee was immune to Sasuke's Sharingan. He explained that a jinchuuriki who can control his bijuu is pretty much immune to genjutsu, because they can call on a huge amount of chakra to override the genjutsu's effects.