Wired has an interesting article up on the Jerusalem Syndrome:
What’s actually happening in the brain, though, isn’t completely clear. Faith isn’t easy to categorize or study. Andrew Newberg, a neuroscientist at Thomas Jefferson University in Philadelphia, has conducted several brain-imaging studies of people in moments of extreme devotion. The limbic system, the center for our emotions, begins to show much higher activity, while the frontal lobes, which might ordinarily calm people, start to shut down. “In extreme cases, that can lead to hallucinations, where someone might believe they’re seeing the face of God or hearing voices,” Newberg says. “Your frontal lobe isn’t there to say, ‘Hey, this doesn’t sound like a good idea.’ And the person winds up engaging in behaviors that are not their norm.”