Lucid dreamers, people who can deliberately control their dreams during sleep, have long fascinated scientists. And now brain scans of those self-aware sleepers could offer insight into the seat of self-reflection in the mind.
It is difficult to get a full picture of what goes on in the brain when we make the transition from sleep to wakefulness. In fact, the specific areas of the brain underlying our restored self-perception and consciousness when we wake up have eluded scientists, according to a statement by the Max Planck Institute of Psychiatry. But a team of researchers was able to get a picture of that isolated activity in lucid dreamers.
"In a normal dream, we have a very basal consciousness, we experience perceptions and emotions but we are not aware that we are only dreaming," study researcher Martin Dresler, of Max Planck, said in a statement. "It's only in a lucid dream that the dreamer gets a meta-insight into his or her state."
Using functional magnetic resonance imaging (fMRI) brain scans, the team compared the activity of the brain during one of these lucid-dreaming periods with the activity just beforehand in a normal dream. Out of four participants, only two lucid-dreaming episodes could be verified as lucid dreams and were long enough to analyze with fMRI, which measures blood flow to brain regions in real time; an increase in blood flow to a specific region is a sign that region is becoming more active.
The results, detailed online July 1 in the journal Sleep, showed that a specific cortical network is activated when lucid consciousness is attained. Michael Czisch, another Max Planck researcher involved in the study, said activity in certain areas of the cerebral cortex spikes within seconds when a lucid state begins.
These regions include the right dorsolateral prefrontal cortex, which has previously been associated with self-assessment, and the frontopolar regions, where the act of evaluating our own thoughts and feelings takes place, Czisch explained in a statement. "The precuneus is also especially active, a part of the brain that has long been linked with self-perception," he said.
Previous research at the Max Planck Institute compared the brain activity of lucid dreamers as they entertained the same thoughts while awake and asleep. The brain activity was similar, if weaker during sleep, the researchers found.
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