Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Robustness during neuron firings

16.11.2015

Superficial cortical interneurons decrease trial-to-trial variability in pyramidal neuron responses to sensory input

Scientists at the research center caesar in Bonn have, in cooperation with the Bernstein Center for Computational Neuroscience, the Max Planck Institute for Biological Cybernetics and the Max Planck Florida Institute for Neuroscience, discovered a potential mechanism of how cortical neurons decrease trial-to-trial variability in their response to sensory input.


Reconstructed single neurons from the rat cortex.

To gain this insight the researchers used computational modeling to generate predictions that were then tested in vivo using electrophysiological measurements.

Even the simplest sensory stimulus is thought to activate millions of synapses throughout the cortex. Until now it has been unclear how the principal neurons of the cortex, or pyramidal neurons, convert these sometimes very noisy inputs arriving at their dendrites into consistent electrophysiological responses, from one event to the next.

To answer this question, scientists in the Department of Behavior and Brain Organization from the research center caesar in Bonn, an Institute of the Max Planck Society, investigated how the neurons in the most superficial part of the mammalian cortex, also known as cortical Layer 1 (L1), interact with the neurons in the underlying cortical layers.

Why is this superficial part of the cortex so special? This part of the cortex only contains one broad class of neuron, an inhibitory neuron, and, in addition, dendrites which arise from excitatory neurons in the other deeper cortical layers.

Although these L1 inhibitory neurons are found only in low numbers, they are perfectly placed to potentially exert their inhibitory force on the dendrites from most underlying cortical layers. Exactly how this would be achieved was unclear, especially when the neurons were encoding stimulus inputs.

Using in vivo patch-clamp electrical recordings, combined with single neuron anatomical reconstruction techniques, scientists were able to reconstruct the 3D morphologies of the recorded L1 interneurons and integrate this anatomical and electrophysiological information into an existing biophysical model of the somatosensory cortex.

Computer simulations using this model suggested that the inhibitory interneurons should reduce the variability of the neural responses to sensory input signals from one trial to the next and thus control the robustness of neural patterns, at least in the dendrites.

This hypothesis derived from the theoretical model was confirmed in vivo by combining targeted electrophysiology and neuronal population imaging using 2-photon microscopy: When L1 interneurons were prevented from being activated, an increase in trial-to-trial variability could be observed, but not a change in the structure of the inputs. This left open the question of the underlying mechanism.

Through further simulations it became apparent that the mechanism that was most consistent with the data was that of distal dendritic shunting, which allows interneurons to have control over the way in which the dendrites integrate inputs arriving during sensory stimulation. In other words, this means that this is one way in which the inhibitory interneurons can influence how pyramidal neurons respond to sensory input and make their responses more consistent from trial to trial.

"A distal dendritic shunting may be - across all sensory modalities – a universal organizational principle of the cortex to specifically control the robustness of sensory-evoked responses", says Jason Kerr, a scientific director at caesar.

Original publication
Egger, R., Schmitt, A.C., Wallace, D.J., Sakmann, B., Oberlaender, M. & Kerr, J.N. (2015) “Robustness of sensory-evoked excitation is increased by inhibitory inputs to distal apical tuft dendrites“, Proc. Natl. Acad. Sci. USA [Epub ahead of print]

DOI: 10.1073/pnas.1518773112

Contact
Dept. Behavior and Brain Organization
Research Center caesar – an Institute of the Max Planck Society
Ludwig-Erhard-Allee 2
53175 Bonn, Germany
+49 (0)228 9656-103
jason.kerr(at)caesar.de

Weitere Informationen:

http://www.caesar.de/1387.html?&L=0

Dr. Jürgen Reifarth | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht Good preparation is half the digestion
15.11.2018 | Max-Planck-Institut für Stoffwechselforschung

nachricht How the gut ‘talks’ to brown fat
16.11.2018 | Technische Universität München

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 Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

Im Focus: Coping with errors in the quantum age

Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly

The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Massive impact crater from a kilometer-wide iron meteorite discovered in Greenland

15.11.2018 | Earth Sciences

When electric fields make spins swirl

15.11.2018 | Physics and Astronomy

Discovery of a cool super-Earth

15.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>