I'd have to do some digging to find the study, but it was theorized (I won't say proven because I'm not entirely certain that it was, and as I said I don't have the study) that conscious imagination works "top-down" and unconscious imagination works "bottom-up". I personally think this would explain why dreams are so complex. They've been built from the bottom up.  Of course, this model fails to explain some things, but to be honest, the answer is that we don't know. The real problem I've found with connecting it to anything is that we don't have anything that correlates with it other than things we either already don't understand or things we theorize come from it.