Credit: © Halfpoint / Fotolia
Using magnetoencephalography, researchers showed that while the human
brain is still able to perceive sounds during sleep, it is unable to
group these sounds according to their organization in a sequence.
the ’60s, with for example the dystopia Brave New World by Aldous
Huxley, in which individuals are conditioned to their future tasks
during sleep. This concept has been progressively abandoned due to a
lack of reliable scientific evidence supporting in-sleep learning
Recently however, few studies showed that the acquisition of
elementary associations such as stimulus-reflex response is possible
during sleep, both in humans and in animals. Nevertheless, it is not
clear if sleep allows for more sophisticated forms of learning.
A study published this August 6 in the journal Scientific Reports
by researchers from the ULB Neuroscience Institute (UNI) shows that
while our brain is able to continue perceiving sounds during sleep like
at wake, the ability to group these sounds according to their
organization in a sequence is only present at wakefulness, and
completely disappears during sleep.
Juliane Farthouat, while a Research Fellow of the FNRS under the
direction of Philippe Peigneux, professor at the Faculty of
Psychological Science and Education at Université libre de Bruxelles,
ULB, used magnetoencephalography (MEG) to record the cerebral activity
mirroring the statistical learning of series of sounds, both during slow
wave sleep (a part of sleep during which brain activity is highly
synchronized) and during wakefulness.
During sleep, participants were exposed to fast flows of pure sounds,
either randomly organized or structured in such a way that the auditory
stream could be statistically grouped into sets of 3 elements.
During sleep, brain MEG responses demonstrated preserved detection of
isolated sounds, but no response reflecting statistical clustering.
During wakefulness, however, all participants presented brain MEG
responses reflecting the grouping of sounds into sets of 3 elements.
The results of this study suggest intrinsic limitations in de novo
learning during slow wave sleep, that might confine the sleeping brain’s
learning capabilities to simple, elementary associations.