Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tinnitus in a computer model

15.09.2008
Scientists from Berlin study how hearing loss can lead to tinnitus

Tinnitus, i.e. the perception of phantom sounds in the absence of an acoustic stimulus, can be caused by hearing loss. Under which circumstances does this occur? Which mechanisms are involved? Roland Schaette and Richard Kempter from the Bernstein Center for Computational Neuroscience and the Humboldt University in Berlin found answers to these questions using computer simulations.

Tinnitus arises in the auditory pathway of the central nervous system. In animal studies, tinnitus-like activity of neurons - so-called hyperactivity - has been found in the dorsal cochlear nucleus (DCN), the first processing stage for acoustic information in the brain. Neurons of the DCN receive input directly from the auditory nerve and react to it with neuronal discharges - one says, they "fire".

Even without any acoustic signals, however, cells of the auditory nerve and the auditory pathway are still active and fire spontaneously at a certain rate, the "spontaneous firing rate" - comparable to the background noise produced by electrical devices. Various studies suggest that hearing loss can increase the spontaneous firing rate of nerve cells in the DCN and that animals perceive this as a kind of tinnitus. In a theoretical model, Schaette and Kempter explain the link between tinnitus and hearing loss for the first time.

After hearing loss, auditory nerve fibers and neurons along the auditory pathway only react to loud sounds. For soft sounds below the increased hearing threshold, the neurons fire spontaneously. Many neurons thus show an overall reduced activity. This could trigger a mechanism called "homeostatic plasticity", which ensures that neuronal activity is neither too high nor too low. If the average activity of the neurons is too low, homeostasis enhances their sensitivity. As the scientists could show in their model, neurons then react more strongly to the activity of the auditory nerve; in particular the spontaneous firing rate increases.

Moreover, Schaette and Kempter also demonstrated in their model that this mechanism only applies to certain types of neurons - for example to type III neurons of the DCN. These neurons are primarily activated by sound. Therefore, their average activity initially drops after hearing loss and the mechanism described above is initiated: homeostasis has to counteract this loss in activity and elevate firing rates, which then also leads to an increased spontaneous firing rate.

In contrast, type IV neurons are either activated or inhibited by sound, depending on sound intensity. Hearing loss only has a minor effect on their average activity. Accordingly, these neurons are less susceptible to hyperactivity. This prediction of the Berlin scientists' model corresponds with experimental findings: In rodents type III neurons dominate in the DCN. Here, tinnitus-like hyperactivity has been observed. In contrast, such an activity has not yet been found in cats, whose DCN mainly holds type IV neurons.

"Our studies have corroborated the association between hearing loss and tinnitus, which could provide a foundation for new treatment strategies," Kempter states. "Our hope would be that a tailored exposure to acoustic signals over an appropriate frequency range could help to drive back the hyperactivity caused by hearing loss".

Original publication:
Schaette R, Kempter R: Development of tinnitus-related neuronal hyperactivity through homeostatic plasticity after hearing loss: a computational model. Europ J Neurosci 23:3124-38 (2006). doi: 10.1111/j.1460-9568.2006.04774.x

Schaette R, Kempter R: Development of hyperactivity after hearing loss in a computational model of the dorsal cochlear nucleus depends on neuron response type. Hear Res 240:57-72 (2008). doi:10.1016/j.heares.2008.02.006

Contact:
Dr. Richard Kempter
Dr. Roland Schaette
Institute for Biology
Department of Theoretical Biology (???)
Humboldt-Universität zu Berlin
Invalidenstraße 43, 10115 Berlin
Tel: + 49 30-2093-8925 (Richard Kempter)
+ 49 30-2093-8926 (Roland Schaette)

Dr. Katrin Weigmann | idw
Further information:
http://www.bernstein-netzwerk.de
http://www.nncn.de
http://www.bccn-berlin.de

More articles from Life Sciences:

nachricht New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

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

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>