User blog comment:Xilinoc/Ch. 567 (Rukia be like "I ain't even scared though")/@comment-1489595-20140205190619/@comment-6007020-20140206211338

Well, if she can freeze the very molecules of, well, anything, who can say she didn't freeze a few neurons in her brain that would produce fear and react to As's power? I know that seems like a Mayuri sort of thing to do, but Rukia's a clever girl.