Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tired neurons caught nodding off in sleep-deprived rats

28.04.2011
Performance decline belies seeming wakefulness, NIH-funded study

A new study in rats is shedding light on how sleep-deprived lifestyles might impair functioning without people realizing it. The more rats are sleep-deprived, the more some of their neurons take catnaps – with consequent declines in task performance.

Even though the animals are awake and active, brainwave measures reveal that scattered groups of neurons in the thinking part of their brain, or cortex, are briefly falling asleep, scientists funded by the National Institutes of Health have discovered.

"Such tired neurons in an awake brain may be responsible for the attention lapses, poor judgment, mistake-proneness and irritability that we experience when we haven't had enough sleep, yet don't feel particularly sleepy," explained Giulio Tononi, M.D., Ph.D., of the University of Wisconsin-Madison. "Strikingly, in the sleep-deprived brain, subsets of neurons go offline in one cortex area but not in another – or even in one part of an area and not in another."

Tononi and colleagues report their findings online in the April 28, 2011 issue of the journal Nature. Their study was funded in part by the NIH's National Institute of Mental health and a NIH Director's Pioneer Award, supported through the Common Fund, and administered by NIMH and the National Institute on Neurological Disorders and Stroke.

Previous studies had hinted at such local snoozing with prolonged wakefulness. Yet little was known about how underlying neuronal activity might be changing.

To learn more, the researchers tracked electrical activity at multiple sites in the cortex as they kept rats awake for several hours. They put novel objects into their cages – colorful balls, boxes, tubes and odorous nesting material from other rats. The sleepier the rats got, more subsets of cortex neurons switched off, seemingly randomly, in various localities. These tired neurons' electrical profiles resembled those of neurons throughout the cortex during NREM or slow wave sleep. Yet, the rats' overall EEG, a measure of brain electrical activity at the scalp, confirmed that they were awake, as did their behavior. So neuronal tiredness differs from more overt microsleep – 3-15-second lapses with eyes closing and sleep-like EEG – that is sometimes experienced with prolonged wakefulness. It is more analogous to local lapses seen in some forms of epilepsy, suggest the researchers.

However subtle, having tired neurons did interfere with task performance. If neurons switched off in the motor cortex within a split second before a rat tried to reach for a sugar pellet, it decreased its likelihood of success by 37.5 percent. And the overall number of such misses increased significantly with prolonged wakefulness. This suggests that tired neurons, and accompanying increases in slow wave activity, might help to account for the impaired performance of sleep-deprived people who may seem behaviorally and subjectively awake.

Subsets of neurons going offline with longer wakefulness is, in many ways, the mirror image of progressive changes that occur during recovery sleep following a period of sleep deprivation. Tononi suggests that both serve to maintain equilibrium – part of the compensatory mechanisms that regulate sleep need. Just as sleep deprivation produces a brain-wide state of instability, it may also trigger local instability in the cortex, possibly by depleting levels of brain chemical messengers. So, tired neurons might nod off as part of an energy-saving or restorative process for overloaded neuronal connections.

"Research suggests that sleep deprivation during adolescence may have adverse emotional and cognitive consequences that could affect brain development," noted NIMH Director Thomas R. Insel, M.D. "The broader line of studies to which this belongs, are, in part, considering changes in sleep patterns of the developing brain as a potential index to the health of neural connections that can begin to go awry during the critical transition from childhood to the teen years."

Reference:

Local sleep in awake rats. Vyazovskiy VV, Olcese U, Hanlon EC, Nir Y, Cirelli C, Tononi G. Nature. 2011 April 28.

Jules Asher | EurekAlert!
Further information:
http://www.nih.gov

Further reports about: EEG NIMH Nature Immunology electrical activity sleep deprivation

More articles from Life Sciences:

nachricht A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich

nachricht New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>