Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Instructing neuronal connections

15.02.2008
Researchers unravel how specific connections result in the layering of neurons in the brain

Information in the brain travels along neuronal axons that form junctions, or ‘synapses’, with tree-like dendrites of other neurons. Normally, the myriad of neuronal pathways develop into highly organized layers called lamina—distinct areas where axons physically meet dendrites, providing a structural basis for integrating information. How such patterning of neurons actually occurs has long eluded brain scientists.

Now, a team led by Shigeyoshi Itohara at the Brain Science Institute in Wako, has determined that adhesion molecules on terminally projecting axons instruct the laminar configuration within ‘target’ dendrites—branches of neurons that receive signals from axons (1). The researchers found that individual dendrites are divided molecularly and functionally into ‘sub-dendritic segments’, each of which corresponds to information input from a specific group of axons.

Netrin-G1 and netrin-G2 belong to a family of molecules that promote attraction between cells. Previous studies have demonstrated that netrin-G1 and -G2 proteins bind specific receptors, NGL-1 and NGL-2, respectively. Itohara’s team initially demonstrated selective expression of netrin-G1 and -G2 on axons that project onto individual layers of the brain cortex and hippocampus (Fig. 1); even layers physically juxtaposed to one another express only one of the netrin-G proteins. Interestingly, the team also found similar laminar patterns of netrin-G partner proteins NGL-1 and NGL-2 on target dendrites.

... more about:
»Axon »Interaction »Neuronal »dendrite »laminar »netrin-G

These one-to-one expression patterns of netrin-G and NGL protein suggested that a ‘lock-and-key’ configuration of the proteins might account for lamina-specific organization within sub-dendritic segments. To address this possibility, the team analyzed mice lacking either netrin-G1 or -G2 and found, surprisingly, disruption of laminar neuronal patterns but normal gross brain structure and arrangements of neurons. Closer examination revealed that in the absence of its netrin-G partner, the cognate NGL protein was now distributed diffusely along a given dendrite rather than restricted to a specific segment.

Itohara and team concluded that the interaction between axon-expressed netrin-G and dendrite-expressed NGL functionally and physically divides dendrites into segments. In other words, ‘trans-neuronal’ mechanisms, rather than cell-intrinsic factors, account for neuronal circuit specificity within a single neuron.

“We are working hard to investigate the role of netrin-G/NGL interactions on structure and function of the neurons, and to understand how netrin-G1- and -G2-dependent neuronal circuits integrate information,” says Itohara. For now, the team’s data point to an essential role for netrin-G/NGL interactions in determining specific interaction between axon projections and dendrites, which give the characteristic laminar organization of the brain.

1. Nishimura-Akiyoshi, S., Niimi, K., Nakashiba, T. & Itohara, S. Axonal netrin-Gs transneuronally determine lamina-specific subdendritic segments. Proceedings of the National Academy of Sciences USA 104, 14801–14806 (2007).

Saeko Okada | ResearchSEA
Further information:
http://www.researchsea.com
http://www.riken.jp

Further reports about: Axon Interaction Neuronal dendrite laminar netrin-G

More articles from Life Sciences:

nachricht New eDNA technology used to quickly assess coral reefs
18.04.2019 | University of Hawaii at Manoa

nachricht New automated biological-sample analysis systems to accelerate disease detection
18.04.2019 | Polytechnique Montréal

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter

  • Coolest and smallest star to produce a superflare found
  • Star is a tenth of the radius of our Sun
  • Researchers led by University of Warwick could only see...

Im Focus: Quantum simulation more stable than expected

A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.

Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...

Im Focus: Largest, fastest array of microscopic 'traffic cops' for optical communications

The technology could revolutionize how information travels through data centers and artificial intelligence networks

Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...

Im Focus: A long-distance relationship in femtoseconds

Physicists observe how electron-hole pairs drift apart at ultrafast speed, but still remain strongly bound.

Modern electronics relies on ultrafast charge motion on ever shorter length scales. Physicists from Regensburg and Gothenburg have now succeeded in resolving a...

Im Focus: Researchers 3D print metamaterials with novel optical properties

Engineers create novel optical devices, including a moth eye-inspired omnidirectional microwave antenna

A team of engineers at Tufts University has developed a series of 3D printed metamaterials with unique microwave or optical properties that go beyond what is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

Fraunhofer FHR at the IEEE Radar Conference 2019 in Boston, USA

09.04.2019 | Event News

 
Latest News

New automated biological-sample analysis systems to accelerate disease detection

18.04.2019 | Life Sciences

Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

18.04.2019 | Physics and Astronomy

New eDNA technology used to quickly assess coral reefs

18.04.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>