MUNICH (eb). In the transition to sleep is apparently re-organized neural networks in the brain. This change in communication between brain regions is reason that people lose sleep consciousness.
plane still awake and fully conscious and seconds later we are asleep. Suddenly, we take external signals only on reduced and no longer are aware of our self-confidence.
What these changes our perception is based, have now scientists at the Max-Planck-Institute for Psychiatry in Munich clarified in a study, which was attended by 25 young healthy volunteers. The study
, the activity of neural networks that connect brain regions with each other when people awake but at rest.
A systematic reorganization takes place
The measurement in the transition to different sleep stages showed that these networks are reorganized systematically. Thus, for example, the hippocampus, a region important for memory processes, already in a light sleep from a network decoupled.
The frontal lobes, important for higher control processes, with increasing depth of sleep even completely excluded from this network, as stated in a release of the Institute.
contrast, neural connections to take attention network only partially - perhaps to respond to external stimuli can still alarming.
This change in communication between brain regions with selbstreflektorischem behavior, action planning and self-perception are associated may, as the cause of our loss of consciousness during sleep are considered, the institute ( Cerebral Cortex online in 2011).
viewed externally, sleep is a passive process for people. But for the brain and the whole organism, it is a condition with altered activity. Because the brain is asleep while less active, its activity, however, not entirely.
nerve cells are organized into different networks while actively communicating. These networks can be detected by functional magnetic resonance imaging and is based on slow (less than 0.1 Hz), spontaneous signal fluctuations.
Some of the anatomical connection is lost
Of the many simultaneously active rest networks of the human brain investigated the Munich researchers the "default mode network" and in the spontaneous time course rebellious network.
Both networks are in people in the waking state and are closely linked to each other for different attentional processes: the "default mode network" supports more inwardly directed attention tasks, for rather the opposite network, the processing of external stimuli.
behave without additional stimulation it in time in opposite directions, the means high measuring signals of a network usually occur during low signals of the other network and vice versa.
The Munich scientists found that both networks change during the sleep onset process itself and also decreases its strict mutual exclusivity. The "default mode network" lost depending on sleep stage some of its anatomical connections.
solved particular parts of the hippocampal formation already in the light sleep from the network. The prefrontal cortex with increasing depth of sleep also lost its connection to the network.
importance for the interpretation of the MRI
Reduced - but to be detected in the deep sleep - were eventually brain regions in the posterior cingulate and precuneus, a part of the parietal cortex.
These brain regions are among the most densely linked areas in the brain. They are associated with alertness and awareness and in their activity affected by drug sedation.
explains the lower activity in the default mode network "during sleep, why people are sleeping no conscious perception capability.
The counter-network was decoupled from sleep stage 2 of its strictly opposing activity, but remains on all sleep stages available - an important indication that probably only enables a sufficient synchronization between different networks more complex functions, however, relevant simple Weckreize can always be processed.
"In clinical practice, should find these proven network changes in the brain that occur even with a short nap, in the future a special account in the interpretation of MRI scans in patients' calls Dr. Phil Sower, doctors at the Munich Institute .
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