An anonymous reader quotes a report from The Guardian: Scientists have unpicked the regions of the brain involved in dreaming, in a study with significant implications for our understanding of the purpose of dreams and of consciousness itself. What's more, changes in brain activity have been found to offer clues as to what the dream is about. Writing in the journal Nature Neuroscience, Siclari and colleagues from the U.S., Switzerland and Italy, reveal how they carried out a series of experiments involving 46 participants, each of whom had their brain activity recorded while they slept by electroencephalogram (EEG) -- a noninvasive technique that involved placing up to 256 electrodes on the scalp and face to monitor the number and size of brainwaves of different speeds. While the experiments probed different aspects of the puzzle, all involved participants being woken at various points throughout the night and asked to report whether they had been dreaming. If the participants had been dreaming, they were asked how long they thought it had lasted and whether they could remember anything about their dream, such as whether it involved faces, movement or thinking, or whether it was instead a vivid, sensory experience. Analysis of the EEG recording reveal that dreaming was linked to a drop in low-frequency activity in a region at the back of the brain dubbed by the researchers the "posterior cortical hot zone" -- a region that includes visual areas as well as areas involved in integrating the senses. The result held regardless of whether the dream was remembered or not and whether it occurred during REM or non-REM sleep. The researchers also looked at changes in high-frequency activity in the brain, finding that dreaming was linked to an increase in such activity in the so-called "hot zone" during non-REM sleep. Further, the team identified the region of the brain which appears to be important in remembering what a dream was about, finding that this recall was linked to an increase in high-frequency activity towards the front of the brain. A similar pattern of activity was seen in the hot zone and beyond for dreams during REM sleep. The upshot is that dreaming is rooted in the same changes in brain activity regardless of the type of sleep.