Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How brains surrender to sleep

23.06.2017

Scientists at the Research Institute of Molecular Pathology (IMP) in Vienna study fundamental aspects of sleep in roundworms. Using advanced technologies, they monitor the activity of all nerve cells in the brain while they are falling asleep and waking up. The journal Science publishes their ground-breaking results this week.

Sleep is a universal trait in animals: every nervous system seems to regularly undergo and require states of relaxation, during which brain activity is drastically altered. Sleep is vital, as we experience in our daily lives, but scientists are still debating why this is the case.


Caption: The illustration shows two worms: the top one is sleeping and most of its nerve cells are quiet, the second is awake with many of its nerve cells vigorously active.

IMP

A team of neurobiologists led by Manuel Zimmer of the IMP Vienna used the roundworm C. elegans to study in detail how the brain switches between wakefulness and sleep. Their results suggest that in tired animals sleep is a ground state of the brain that spontaneously establishes itself as long as strong external stimuli from the environment are absent.

Manuel Zimmer compares such a state to a marble resting in a valley; to push it uphill requires some effort, but it will roll back by itself when left on its own. The equivalent is to arouse a sleeping worm, thereby pushing its brain into wakefulness, but if still tired and left unperturbed it will fall back to sleep.

Scientists who deal with complex dynamical systems use the term ‘attractor’ for such processes. ‘We propose this attractor mechanism as an efficient means how overarching states like sleep and wakefulness can propagate throughout an entire brain’, says Zimmer.

Worms as models for sleep research

C. elegans was chosen as a model for sleep research because its nervous system consists of only 302 neurons. It is small enough for advanced microscopy approaches enabling access to the activity of all nerve cells in the brain at single-cell precision. This was key for obtaining new insights when monitoring the widespread reconfigurations that the brain undergoes between wakefulness and sleep.

Another challenge that the scientists faced was to control when worms would fall asleep and wake up. PhD-students Annika Nichols and Tomáš Eichler established an intriguing experimental system using variable oxygen concentrations as a switch. In their natural habitat, C. elegans live in soil where abundant microorganisms keep oxygen levels low.

The researchers showed that under these preferred conditions the worms felt comfortable and could fall asleep, provided they were tired. Nichols and Eichler found that fresh air with atmospheric oxygen content alarms sleeping animals, causing them to rapidly wake up. ‘This opened a door to effectively switch between the sleep and wake states during our experiments’, says Nichols.

A neural meter for tiredness

Nichols went on and recorded the activity of all neurons in the brain while triggering switches between sleep and wakefulness. She found that during sleep, most nerve cells that are vigorously active during wakefulness, become silent. However, a few specific types of nerve cells stay alert. One of these types, termed RIS, was previously shown to promote sleep by excreting a sleep substance. Nichols showed that RIS activity is already elevated in awake animals that are prone to sleep, hinting that it is a measure of how tired the brain is.

Sleep as a default attractor state of the brain

When monitoring the activity of the brain as it fell asleep, Nichols made an interesting discovery: her computer analyses indicated that neuronal network activity spontaneously converged to a quiet and stable state. Originally, the researchers had assumed that RIS cells would force the nervous system into quiescence much like a conductor who silences the orchestra after the final chord. However, the new data suggest that RIS seems to act more like a mediator who negotiates an agreement between all players, followed by a collective action. The advantage of this scenario is that the dramatic changes between wakefulness and sleep can be triggered by rather subtly turning some of the regulatory knobs in the brain.

Despite the many differences between a worm brain and the human brain, these results provide a promising model for studying fundamental principles of brain organisation.

Original Publication

A global brain state underlies C. elegans sleep behavior. Annika L. A. Nichols, Tomáš Eichler, Richard Latham, Manuel Zimmer. Science 356, 23 June 2017.

Illustration An illustration can be downloaded and used free of charge in connection with this press release: https://www.imp.ac.at/news.
Caption: The illustration shows two worms: the top one is sleeping and most of its nerve cells are quiet, the second is awake with many of its nerve cells vigorously active.

About the IMP

The Research Institute of Molecular Pathology (IMP) in Vienna is a basic biomedical research institute largely sponsored by Boehringer Ingelheim. With over 200 scientists from nearly 40 nations, the IMP is committed to scientific discovery of fundamental molecular and cellular mechanisms underlying complex biological phenomena. In particular, research at the IMP addresses topics in molecular and cellular biology; structural biology and biochemistry gene expression and chromosome biology; stem cell biology and development; immunology and cancer; and neuroscience. The IMP is located at the Vienna BioCenter. www.imp.ac.at 

About the Vienna BioCenter

Vienna BioCenter (VBC) is a leading life sciences location in Europe, offering an extraordinary combination of research, business and education on a single campus. About 1.700 employees, 86 research groups, 17 biotech companies, 1.300 students, and scientists from more than 40 nations create a highly dynamic environment of international standards. www.viennabiocenter.org

Weitere Informationen:

https://www.imp.ac.at/news

Dr. Heidemarie Hurtl | idw - Informationsdienst Wissenschaft

Further reports about: IMP Molekulare Pathologie elegans nerve cells nervous system sleep sleep research sleeping

More articles from Life Sciences:

nachricht Intestinal inflammation: immune cells protect nerve cells after infection
22.01.2020 | Exzellenzcluster Präzisionsmedizin für chronische Entzündungserkrankungen

nachricht Structual color barcode micromotors for multiplex biosensing
21.01.2020 | Science China Press

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A new look at 'strange metals'

For years, a new synthesis method has been developed at TU Wien (Vienna) to unlock the secrets of "strange metals". Now a breakthrough has been achieved. The results have been published in "Science".

Superconductors allow electrical current to flow without any resistance - but only below a certain critical temperature. Many materials have to be cooled down...

Im Focus: Programmable nests for cells

KIT researchers develop novel composites of DNA, silica particles, and carbon nanotubes -- Properties can be tailored to various applications

Using DNA, smallest silica particles, and carbon nanotubes, researchers of Karlsruhe Institute of Technology (KIT) developed novel programmable materials....

Im Focus: Miniature double glazing: Material developed which is heat-insulating and heat-conducting at the same time

Styrofoam or copper - both materials have very different properties with regard to their ability to conduct heat. Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz and the University of Bayreuth have now jointly developed and characterized a novel, extremely thin and transparent material that has different thermal conduction properties depending on the direction. While it can conduct heat extremely well in one direction, it shows good thermal insulation in the other direction.

Thermal insulation and thermal conduction play a crucial role in our everyday lives - from computer processors, where it is important to dissipate heat as...

Im Focus: Fraunhofer IAF establishes an application laboratory for quantum sensors

In order to advance the transfer of research developments from the field of quantum sensor technology into industrial applications, an application laboratory is being established at Fraunhofer IAF. This will enable interested companies and especially regional SMEs and start-ups to evaluate the innovation potential of quantum sensors for their specific requirements. Both the state of Baden-Württemberg and the Fraunhofer-Gesellschaft are supporting the four-year project with one million euros each.

The application laboratory is being set up as part of the Fraunhofer lighthouse project »QMag«, short for quantum magnetometry. In this project, researchers...

Im Focus: How Cells Assemble Their Skeleton

Researchers study the formation of microtubules

Microtubules, filamentous structures within the cell, are required for many important processes, including cell division and intracellular transport. A...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

„Advanced Battery Power“- Conference, Contributions are welcome!

07.01.2020 | Event News

 
Latest News

Intestinal inflammation: immune cells protect nerve cells after infection

22.01.2020 | Life Sciences

A new look at 'strange metals'

21.01.2020 | Materials Sciences

Body's natural signal carriers can help melanoma spread

21.01.2020 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>