Creating dreams This article outlines an experiment detailing how the brain is very active during dream states. I believe this implies that the brain and its associated zones have to be activated to create an inner dream scape. Furthermore researchers have registered frontal lobe activity on participants that were asked to try and remember their dreams after being woken up.
Psychedelics and Default Mode Network (DMN)Psychedelics and Temporal LobePsychedelic research is pointing out that psychedelics molecules are active centrally in the temporal lobe and decreasing the functioning of the default mode network. To read further click the two above links.
Dreams and Default Mode NetworkIn the above article researchers have been able to establish that the functioning of the default mode network is decreased during dreams which is also being suggested of other altered states of consciousness such as during psychedelic use and meditation.
Dreaming and the hippocampusThe above article details a study detailing how the hippocampus must be somewhat responsible for dreaming. Hippocampus damage also has ties to dementia.
Hippocampal Neurogenesis and PsychedelicsThe above article details how psychedelics elicit neurogenesis in hippocampus regions.
I thought the parallels between research are curious enough to warrant further thought to how and why these states produce similar effects on our human brains. Further I think it is important to mention the neurogenesis behavior of psychedelics and the relation to dementia, people experiencing amnesia and Alzheimers disease.