Brain centers shut off during deep sleep: Study

Brain centers shut off during deep sleep: Study

MADISON, Wis.: The brain never goes to sleep when you do but it does disconnect its higher regions, according to a new report published in the latest issue of the journal Science.

Researchers from the University of Wisconsin found that the brain disconnects in parts during deep sleep in the first major experiment on consciousness. The researchers led by psychiatry professor Giulio Tononi used a non-invasive technique to map the electrical activity of the brain. Using an entirely new system that provides stimulation using a magnetic field, the scientists were able to better understand how the brain functions when a person sleeps.

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They attached electrodes (an 'electroencephalogram' cap) to the heads of subjects and monitored how each stimulation caused a reaction elsewhere in the body.

Team leader Tononi said his team now had conclusive proof that the brain never stops working during sleep but during the deepest part of sleep it does disconnect many of its nodal regions (centers), effectively leading to lack of consciousness.

The scientist explained consciousness using the analogy of the Internet which is but a large and complex network of servers, computers and routers. During deepest sleep many of the servers shut down causing a break in the nonstop data traffic between the various nodal points and the peripheral locations. At such times, the brain is like many small islands that cannot communicate with each other.

The MRI reconstruction showed that when the subjects were dreaming, especially in the early hours of the morning, electrical signals were nearly as active as when the person is awake. This was in complete contrast to when the person started getting into deep sleep.

The break during deep sleep helps refresh and revitalize the brain by relaxing the synapses. By compartmentalizing the brain during sleep, 'noisy synapses' (over-burdened brain centers) get the chance to relax and prepare for the next day.

Tononi's team was joined in this effort by researchers from the University of Milan.