Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Clock for brain waves

19.11.2014

Inhibitory neurons and electrical synapses determine the frequency of rhythmic activity in the brain

Oscillations of brain activity influence our attention and many other mental functions. Tatjana Tchumatchenko from the Max Planck Institute for Brain Research in Frankfurt and Claudia Clopath from Imperial College London have now developed a theoretical model that explains the origin of such oscillations in neural networks.


Netzwerk aus Nervenzellen in der Hirnrinde (Federn: elektrische Synapsen, Linien: chemische Synapsen). Die elektrischen Synapsen sind wichtig für rhythmische Netzwerk-weite Aktivitätsschwankungen.

© MPI f. Hirnforschung/ T. Tchumatchenko

Inhibitory neurons and electrical synapses play key roles and could therefore serve as targets for new drugs.

Alpha and gamma brain waves, which are visualized by means of electroencephalography (EEG) measurements, can provide doctors with information about a patient’s mental state for diagnostic purposes.

The mysterious term “brain waves” denotes nothing more than synchronous oscillations in the activity of groups of neurons that are often spread over large parts of the brain. The Greek letters indicate the oscillation frequency, which ranges from one hertz for alpha waves to several hundred hertz for theta waves. The waves act as a clock for the human brain and control attention, perception and memory formation.

The results of numerous experimental studies have shown that certain classes of neurons exert greater influence on network oscillations than others. Inhibitory neurons, which make up about 20 percent of the nerve cells in the cerebral cortex, appear to play a key role in the generation of brain waves.

However, it is unknown how inhibitory neurons control these oscillations. Because brain waves are a network phenomenon, it is also not clear how the properties of individual cells are reflected in network dynamics, or whether only synaptic connections are important.

Tatjana Tchumatchenko from the Max Planck Institute for Brain Research in Frankfurt and Claudia Clopath from Imperial College London are convinced that mathematics can deepen our understanding of the phenomenon of brain waves. In their joint work, they developed a mathematical framework that models the activity of excitatory and inhibitory neurons in a network such as the human cerebral cortex.

“We are able to reliably reproduce results from previous experiments using an analytical and numeric approach and our mathematical model has revealed two new conditions essential for the emergence of brain waves,” says Tatjana Tchumatchenko. “First, the individual inhibitory neurons must exhibit subthreshold resonance of the membrane potential at the preferred network oscillation frequency, i.e. they have to oscillate in time, although their electrical impulses do not necessarily reveal this oscillation.”

But the type of synaptic connectivity is also important, as oscillations occur only if the inhibitory neurons are interlinked by electrical synapses of sufficient connection strength.

Until recently, electrical synapses in the cerebral cortex were largely unknown, but are now known to occur in many areas of the brain. However, only inhibitory neurons are electrically coupled. This type of signal transmission has not been observed between excitatory neurons.

Inhibitory neurons and their synaptic connections therefore play a central role, say the researchers: “Amazingly, our model shows that the oscillation frequency of the entire network is determined only by the properties of inhibitory neurons and their connections, despite the fact that the majority of neurons are of the excitatory type,” says Claudia Clopath. “Of course,” she adds, “the properties of excitatory neurons help shape the dynamics of the network, but they only determine the amplitude of brain waves, not their frequency of oscillation.”

The knowledge gained will advance our understanding of complex systems and help explain the interplay between single network units and the arising network dynamics. The research results may also contribute to the development of more targeted drugs that could improve the chances for successful treatment in psychiatric care.


Contact

Amadeus Dettner
Max Planck Institute for Brain Research, Frankfurt am Main

Email: amadeus.dettner@brain.mpg.de

 
Dr. Tatjana Tchumatchenko
Max Planck Institute for Brain Research, Frankfurt am Main

Email: tatjana.tchumatchenko@brain.mpg.de


Original publication
Tatjana Tchumatchenko und Claudia Clopath

Oscillations emerging from noise-driven steady state in networks with electrical synapses and subthreshold resonance

Nature Communications, 18 November 2014

Amadeus Dettner | Max-Planck-Institute
Further information:
http://www.mpg.de/8764344/brain-waves-clock

More articles from Life Sciences:

nachricht Unique genome architectures after fertilisation in single-cell embryos
30.03.2017 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

nachricht Transport of molecular motors into cilia
28.03.2017 | Aarhus University

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 Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

NASA laser communications to provide Orion faster connections

30.03.2017 | Physics and Astronomy

Reusable carbon nanotubes could be the water filter of the future, says RIT study

30.03.2017 | Studies and Analyses

Unique genome architectures after fertilisation in single-cell embryos

30.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>