A news report from The Verge discusses a French study about dreams that found a link between REM sleep and specific areas of the brain in rats.
Humans (and rats) cycle through several stages of sleep every night, and dreaming is possible across multiple stages. But the vivid, elaborate dreams we tend to remember most clearly occur during REM (rapid eye movement) sleep. There’s a lot of similarity between imagining doing something in this state and deciding to do it in real life — if our muscles weren’t usually paralyzed, we’d start to act out our dreams. The brain activity that produces them, though, is quite different. This latest research found that in rats, REM sleep is associated with only a handful of substructures, which might ultimately be controlled by an even smaller set of structures.