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 Study suggests oysters offer hot spot for reducing nutrient pollution
17.10.2017 | Virginia Institute of Marine Science

nachricht World first for reading digitally encoded synthetic molecules
17.10.2017 | CNRS

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

Im Focus: New nanomaterial can extract hydrogen fuel from seawater

Hybrid material converts more sunlight and can weather seawater's harsh conditions

It's possible to produce hydrogen to power fuel cells by extracting the gas from seawater, but the electricity required to do it makes the process costly. UCF...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Study suggests oysters offer hot spot for reducing nutrient pollution

17.10.2017 | Life Sciences

Breaking: the first light from two neutron stars merging

17.10.2017 | Physics and Astronomy

World first for reading digitally encoded synthetic molecules

17.10.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>