Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Clock for brain waves


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.


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


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


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:

More articles from Life Sciences:

nachricht ‘Farming’ bacteria to boost growth in the oceans
24.10.2016 | Max-Planck-Institut für marine Mikrobiologie

nachricht Calcium Induces Chronic Lung Infections
24.10.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Oasis of life in the ice-covered central Arctic

24.10.2016 | Earth Sciences

‘Farming’ bacteria to boost growth in the oceans

24.10.2016 | Life Sciences

Light-driven atomic rotations excite magnetic waves

24.10.2016 | Physics and Astronomy

More VideoLinks >>>