Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Right time, right place

27.06.2014

To orient ourselves in space, our brain generates an internal coordinate system. Heidelberg researchers now refute the current model on how nerve cells generate this mental map.

The food pellet must be further away—a mouse is foraging for food. To estimate distances and to orient itself in space, the brain forms an internal spatial map. So-called grid neurons take on an important role in this process. They fire when the mouse happens to be at decisive positions.


Grid neurons are essential for space orientation. They fire when the mouse happens to be at decisive positions. Seen from above, the activity pattern of a cell forms a hexagonal pattern in space.

Christina Buetfering, 2014

From a bird's perspective, the activity pattern of a grid cell forms a hexagonal pattern in space—very reminiscent of a coordinate system on a map (see figure). But how is this abstract activity pattern generated that is not based on sensory input from the environment?

To find answers, researchers investigated neuronal connections by means of theoretical models. The currently most promising model is now refuted by scientists from the Bernstein Center Heidelberg/Mannheim and the Department of Clinical Neurobiology at the Medical Faculty of Heidelberg University and The German Cancer Research Center (DKFZ), who put the model to test in animal experiments.

"In our study, we measured the nerve cell activity in freely moving mice," explains Christina Buetfering, first author of the study. "We were interested in grid cells as well as nerve cells that interconnect the grid cells: so-called interneurons".

The crucial trick: the activity of interneurons could be selectively switched on and off by light signals in genetically modified mice. While the mice moved around during foraging, the researchers activated the cells now and then. This helped them to identify and closely observe the interneurons in the measured data stream. Also, they were able to analyze how grid cells responded to the activity of interneurons—giving a hint on how the neurons must be connected.

The scientists discovered that interneurons show no spatial activity patterns like grid cells do. In addition, individual interneurons are not exclusively connected to grid cells with similar activity patterns. Instead, they get their input signals from very different grid cells and send their output information to diverse nerve cells.

"With these results we were able to refute two basic predictions of the current theoretical network model," Buetfering discusses. "The model assumes that for generating the inner mental map, grid cells of the same spatial orientation must be very closely connected—which was thought to be realized via spatially active interneurons."

However, interneurons seem to have a different main task. The cells send inhibitory signals to quite different neurons in their environment. Therefore, they possibly rather take over a modulating function by ensuring a balance between excitation and inhibition in the brain area during excessive nerve cell activity.

In this way they could prevent epileptic seizures. How grid cells manage to fire at the right time at the right place—thereby generating the abstract mental coordinate system—has, once again, become more mysterious.

The Bernstein Center Heidelberg/Mannheim is part of the National Bernstein Network Computational Neuroscience in Germany. With this funding initiative, the German Federal Ministry of Education and Research (BMBF) has supported the new discipline of Computational Neuroscience since 2004 with over 180 million Euros. The network is named after the German physiologist Julius Bernstein (1835-1917).

Contact:
Prof. Dr. Hannah Monyer
Clinical Neurobiology (A230)
German Cancer Research Center
Im Neuenheimer Feld 280
69120 Heidelberg
Tel: +49 (0)6221 42 3100
Email: h.monyer@dkfz.de

Original publication:
C. Buetfering, K. Allen & H. Monyer (2014): Parvalbumin interneurons provide grid cell-driven recurrent inhibition in the medial entorhinal cortex. Nature Neuroscience, advanced online publication
doi: 10.1038/nn.3696

Weitere Informationen:

http://www.dkfz.de/de/klinische-neurobiologie Lab Hannah Monyer
http://www.uni-heidelberg.de Heidelberg University
http://www.klinikum.uni-heidelberg.de Heidelberg University Hospital
http://www.dkfz.de German Cancer Research Center
http://www.bccn-heidelberg-mannheim.de Bernstein Center Heidelberg/Mannheim
http://www.nncn.de National Bernstein Network Computational Neuroscience

Mareike Kardinal | idw - Informationsdienst Wissenschaft

Further reports about: Bernstein Cancer Computational Neurobiology Neuroscience activity crucial foraging neurons spatial

More articles from Life Sciences:

nachricht Fingerprint' technique spots frog populations at risk from pollution
27.03.2017 | Lancaster University

nachricht Parallel computation provides deeper insight into brain function
27.03.2017 | Okinawa Institute of Science and Technology (OIST) Graduate 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: 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...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

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

Northern oceans pumped CO2 into the atmosphere

27.03.2017 | Earth Sciences

Fingerprint' technique spots frog populations at risk from pollution

27.03.2017 | Life Sciences

Big data approach to predict protein structure

27.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>