GUEST BLOG / By David Neld, Nature Neuroscience--We now know much more about when we dream, the parts of the brain involved, and what we dream about, thanks to new research – and experts say it's one of the most important studies ever published on dreaming.
Not only does the research give us a better understanding of
how and when we dream, it could lead to ways of inducing sleep and even
manipulating dreams, for those who struggle with nightmares and insomnia.
Scientists from the University of Wisconsin-Madison
identified a new "hot zone" of electrical activity in the brain that
indicates dreaming, and showed that much of our dreaming happens outside REM
(rapid eye movement) sleep, even if we
can't remember our dreams when we wake up.
What's more, the study showed that areas of the brain we use
when we're awake can also take on the same tasks when we're sleeping – tasks
like recognising faces in dreamland.
“We were able to compare what changes in the brain when we
are conscious, that is, when we are dreaming, compared when we are unconscious,
during the same behavioural state of sleep," says
one of the researchers, psychiatrist
Giulio Tononi.
"In this way we could zoom in on the brain regions that
truly matter for consciousness and avoid confounding factors having to do with
being awake rather than asleep or anaesthetized."
A total of 46 volunteers were recruited for the study,
sleeping in the Wisconsin Institute of Sleep and Consciousness (WISC) lab and
wearing caps with 256 electrodes to measure brain and facial activity. At
various points the participants were woken up and asked about their dreams.
One experiment spotted changes in activity during dreaming
in a region at the back of the brain that the researchers called the 'posterior
cortical hot zone', which usually helps our brains process visuals and
integrate our senses.
The same pattern of activity was seen during REM and non-REM
sleep, no matter what the rest of the brain was doing – it's "a signature
of the dreaming brain", researcher Francesca Siclari told
Nicola Davis at The Guardian.
By monitoring this 'hot zone' and then waking the
participants up, the team was able to accurately predict whether the volunteers
were dreaming 87 percent of the time.
Up until now, scientists haven't been able to find tell-tale
signs of non-REM dreaming, and there have been doubts that it's even happening
at all. Are our non-REM dreams just memories
of dreams during REM sleep?
The new research suggests not, and based on the responses of
the study volunteers, we're still doing plenty of dreaming during our shut-eye
even if we
don't remember everything when we
wake up.
Another experiment looked at the content of dreams, and
researchers were able to link brain activity happening during dreams with
similar brain activity that happens when we're not asleep, such as parts of the
brain used for facial recognition.
"This suggests that dreams recruit the same brain
regions as experiences in wakefulness for specific contents," says
Siclari.
"This also indicates that dreams are experiences that
truly occur during wakefulness, and that they are not 'inventions' or
'confabulations' that we make up while we wake up."
The experiments also linked greater activity in the prefrontal cortex during dreaming – the part of the brain associated
with memory – and a better recall of those dreams.
"Maybe the dreaming brain and the waking brain are much
more similar than one imagined," adds
Siclari.
While we're still a long way from being able to manipulate
our dreams Inception-style, the research teaches us a lot about dreaming: such
as how only a small area of the brain is needed to generate dreams that feel
like consciousness.
Many future studies can now be based on this work, the
researchers say, such as further investigations into whether we dream in order
to process the memories of the day.
Christoph Nissen, from University Psychiatric Services in
Switzerland, wasn't involved in the study but told
Chelsea Whyte at New Scientist that
this new brain map could open up ways of modulating sleep, perhaps to suppress
nightmares for people with PTSD or to treat insomnia.
Meanwhile, other experts have been quick to praise the
researchers' work.
"The importance beyond the article is really quite
astounding," Mark Blagrove of Swansea University's sleep lab, who wasn't
involved in the research, told The
Guardian.
"It is comparable really to the discovery of REM sleep
and in some respects it is even more important."
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SLEEP AND DIMENTIA
http://www.medscape.com/viewarticle/881432
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