Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Extreme events in the brain

26.02.2016

Physicists at the Universities of Bonn and Oldenburg have developed a model whose behavior – although based on strict rules – can apparently change spontaneously. There are also changes of this type in nature, for example, in the development of migraine attacks or epileptic seizures. The mechanism, described for the first time by the researchers, could help to better understand extreme events such as these. The work will be published soon in the professional journal "Physical Review X", and it is already available online.

Irregular fiery red rings move across the computer screen. They enlarge, merge together, dissipate, form offspring – a constant cycle of emergence and decay. But suddenly the screen grows dark; the rings have disappeared. For a few seconds, nothing happens.


A so-called chaotic saddle which describes the behavior of the model developed in Bonn and Oldenburg. It can be understood as a type of curved horse saddle on which a ball is rolling along.

(c) Image: Neurophysics Group of the Department of Epileptology Bonn

Then the dark surface begins to pulsate. It rhythmically changes its color, almost imperceptibly at first but this becomes clearer. Shortly thereafter there is a second change: The entire surface suddenly flashes red. Finally, the rings reappear; the extreme event is over.

Something similar may appear in the brain when a migraine attack begins or an epileptic seizure develops: Suddenly, billions of neurons simultaneously enter an exceptional state. The rules which they normally obey appear to be overridden all at once.

The software depicting its results on the computer screen in the office of the Department of Epileptology at the University of Bonn Hospital shows very similar behavior: Seemingly out of nowhere, at completely unpredictable intervals, the underlying model changes its dynamics. What is astonishing is that it actually obeys simple rules which nonetheless create a kind of randomness.

Small-world effects

This model is a network of many thousands of individual elements, the nodes. These are interconnected – they can thus communicate with and influence each other. In this process, they interact not only with their neighbors but also with some remote nodes. Scientists refer to a "small-world" network. Nerve cells in the brain communicate with each other in a very similar way.

Although the rules of communication are precisely determined, networks of this type demonstrate a very complex behavior. On the one hand, this is due to the multitude of nodes, and on the other hand due to the wiring connecting these nodes. "We have now been able to show that the behavior of such networks can spontaneously change," explains Gerrit Ansmann, lead author of the work and doctoral candidate in the Neurophysics group.

"However, these changes only occur under certain conditions," explains Prof. Dr. Klaus Lehnertz, head of the group. "We hope, with our model, to be able to better understand the conditions under which extreme events develop in the brain."

The switching between various patterns of activity including the generation and termination of extreme events is based on a fundamental mechanism, which can also be translated to other system, e.g. to patterns of excitation in the heart. “This generality allows for broad applications of our findings in other scientific fields”, underlines Prof. Dr. Ulrike Feudel, head of the group Theoretical Physics/Complex Systems at the Institute for Chemistry and Biology of the Marine Environment of the University of Oldenburg.

The work is part of a project funded by the Volkswagen foundation. In this project, the scientists investigate the mechanisms through which extreme events develop using the examples of epileptic seizures and toxic algal blooms.

Publication: Gerrit Ansmann, Klaus Lehnertz and Ulrike Feudel: Self-induced switchings between multiple space–time patterns on complex networks of excitable units

Media contact information:

Prof. Dr. Klaus Lehnertz
Neurophysics Group
Department of Epileptology
University of Bonn Hospital
Tel. ++49-228-28715864
E-Mail: Klaus.Lehnertz@ukb.uni-bonn.de

Prof. Dr. Ulrike Feudel
Theoretical Physics/Complex Systems
Institute for Chemistry and Biology of the Marine Environment
Carl von Ossietzky University Oldenburg
Tel. ++49-441-7982790
E-Mail: ulrike.feudel@uni-oldenburg.de

Weitere Informationen:

http://arxiv.org/abs/1602.02177 Publication online

Johannes Seiler | idw - Informationsdienst Wissenschaft

More articles from Physics and Astronomy:

nachricht Discovery of an Extragalactic Hot Molecular Core
29.09.2016 | National Astronomical Observatory of Japan

nachricht Swiss space research reaches for the sky
29.09.2016 | Schweizerischer Nationalfonds SNF

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: New welding process joins dissimilar sheets better

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

HLF: From an experiment to an establishment

29.09.2016 | Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

 
Latest News

New Multiferroic Materials from Building Blocks

29.09.2016 | Materials Sciences

Silicon Fluorescent Material Developed Enabling Observations under a Bright “Biological Optical Window”

29.09.2016 | Materials Sciences

X-shape Bio-inspired Structures

29.09.2016 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>