Interesting stuff. The fact that lobotomy was often used to treat schizophrenia - a catastrophic failure of rationality - is suggestive.

I vaguely remember a neuroscience lecturer of mine saying that a possible factor in the bizarre nature of dreams was that frontal regions were inhibited during sleep, so the dreamer has no way of telling the difference between plausible and implausible scenarios among those they are perceiving. I can't find any references to substantiate this though. Maybe I dreamt it.