Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cells that show where things are going

05.02.2016

Neurobiologists characterize nerve cells that detect motion by light changes

The ability to see the direction in which something is moving is vital for survival. Only in this way is it possible to avoid predators, capture prey or, as humans in a modern world, cross a road safely. However, the direction of motion is not explicitly represented at the level of the photoreceptors but rather must be calculated by subsequent layers of nerve cells.


Clarity in the cellular thicket. Four classes of nerve cell (Tm9, 4, 1 and 2) are instrumental in calculating directionally selective signals in T5 neurons (yellow).

© MPI of Neurobiology

Scientists from the Max Planck Institute of Neurobiology in Martinsried have now discovered that, in fruit flies, four classes of nerve cell are involved in calculating directionally selective signals. This is strikingly different from mathematical models of motion detection discussed in the literature so far.

When crossing a road, it’s advantageous to know the direction in which nearby cars are moving. However, the individual light sensitive cells in the eye only signal local changes in brightness, whether an image point becomes brighter or darker. The direction of motion is detected in a downstream neuronal network.

Alexander Borst and his team at the Max Planck Institute of Neurobiology have unravelled cell by cell how the brain calculates motion from light changes. Their model is the fruit fly, a master in motion vision, possessing a relatively small brain.

Although there are more than 50,000 nerve cells in the area of the fruit fly brain responsible for motion vision, the researchers believe that the network is “simple” enough to allow them to understand the circuitry at the cellular level. In previous studies, they have shown that in flies, similar to vertebrates, motion is detected in two parallel pathways, one for moving bright edges (ON-pathway) and one for moving dark edges (OFF-pathway).

The scientists have now succeeded in identifying the first nerve cells in the fruit flies’ OFF-pathway, known as T5 cells, which perceive the direction of motion. These cells receive input from four upstream cells, called Tm cells. A whole series of experiments based on two-photon microscopy, electrophysiology and behavioural analyses have shown that Tm cells are activated specifically by “light OFF” brightness changes. In contrast, T5 cells are only activated by motion of OFF-edges in a specific direction.

The signals of all four Tm cells are required for a directionally selective signal to arise in a T5 cell. “That was a surprising finding, because mathematical models for motion detection only involved two input cells,” reports Etienne Serbe, one of the two lead authors of the study. “Another exciting finding is that the visual system of vertebrates deviates from these models in a similar way,” says Matthias Meier, the other lead author.

Alexander Borst and a colleague have recently demonstrated the many common features in the visual circuits of flies and mice (review article in Nature Neuroscience). “This recently discovered commonality also shows that we can gain fundamental insights into the circuitry of the brain from investigations of the fly”, says Alexander Borst. “I’m already curious about what we will discover next in the motion circuit.”


Contact

Dr. Stefanie Merker
Max Planck Institute of Neurobiology, Martinsried
Phone: +49 89 8578-3514

Email: merker@neuro.mpg.de

Prof. Dr. Alexander Borst
Max Planck Institute of Neurobiology, Martinsried
Phone: +49 89 8578-3251

Fax: +49 89 8578-3252

Email: borst@neuro.mpg.de


Original publication
Etienne Serbe, Matthias Meier, Aljoscha Leonhardt und Alexander Borst

Comprehensive characterization of the major presynaptic elements to the Drosophila OFF motion detector.

Neuron; 4 February, 2016

Dr. Stefanie Merker | Max Planck Institute of Neurobiology, Martinsried

More articles from Life Sciences:

nachricht Decoding the genome's cryptic language
27.02.2017 | University of California - San Diego

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

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Safe glide at total engine failure with ELA-inside

On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded after a glide flight with an Airbus A320 in ditching on the Hudson River. All 155 people on board were saved.

On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded...

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...

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

New pop-up strategy inspired by cuts, not folds

27.02.2017 | Materials Sciences

Sandia uses confined nanoparticles to improve hydrogen storage materials performance

27.02.2017 | Interdisciplinary Research

Decoding the genome's cryptic language

27.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>