Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fish on the run

29.06.2015

Researchers describe how an approaching object triggers a flight reaction in the fish brain

Humans and animals instinctively evade rapidly approaching objects. By doing so, they avoid collisions or escape attacking predators. For this to happen, the brain must calculate the direction and speed of a stimulus in the visual system and initiate an appropriate evasive reaction.


The zebrafish tectum recognizes an approaching object as a threat. This brain area is innervated by axons from the eye (stained blue).

© Max Planck Institute of Neurobiology / Temizer

How the brain achieves this is largely unclear. Scientists from the Max Planck Institute of Neurobiology in Martinsried have now shown in zebrafish larvae what is interpreted as an approaching foe and which area of the brain recognizes an object as a threat and initiates a flight reaction.

Duck! In most cases, this warning is not necessary when we see an object approaching on collision course. Whether in a fly, fish, mouse or human, such situations generally trigger a stereotypical evasive reaction. In this way, potential predators or injury can be avoided.

“Because this behaviour is so similar across the entire animal kingdom, there is probably a hardwired programme for it in the brain,” says Incinur Temizer, summarizing the essence of her doctoral dissertation. In Herwig Baier’s Department at the Max Planck Institute of Neurobiology, she is studying, based on this example, how the brain converts sensory impressions into behavioural responses.

Incinur Temizer and her colleague Julia Semmelhack have now shown that zebrafish larvae measuring just a few millimetres in length flee from a two-dimensional representation of an object moving towards them. To pinpoint the location of the responsible circuit in the brain, the scientists first determined what exactly triggers the flight reflex.

In a series of experiments, they showed the fish a range of objects that differed in size, brightness and speed. The results showed that the flight reflex is most reliably triggered by a dark disc that "looms", meaning that it gradually increases in size.

The researchers then used optical methods to measure brain activity in response to this “key stimulus”. This is possible, as the tiny fish larvae are completely transparent. Thanks to a genetic modification, the brain areas that are active fluoresce under a microscope. In this way, the scientists were gradually able to narrow down the precise area of the brain that recognizes an approaching enemy and triggers a flight reflex.

The image of a looming object on the retina activates highly specific ganglion cells, which then relay the information to an area in the fish’s brain known as the tectum. The tectum assigns objects to a location in visual space and coordinates movement towards or away from such objects.

“We were able to show, for the first time, that neurons in the retina recognize an approaching object and trigger an evasive reaction through links to the tectum,” says Julia Semmelhack, summarizing the findings of the recently published study. That the tectum is really critical became clear when the researchers cut off the input of these retinal ganglion cells: such fish larvae were not entirely blind but no longer responded to approaching objects.

Contact

Dr. Stefanie Merker

Max Planck Institute of Neurobiology, Martinsried
Phone: +49 89 8578-3514

Email: merker@neuro.mpg.de

Prof. Dr. Herwig Baier
Max Planck Institute of Neurobiology, Martinsried
Phone: +49 89 8578-3200

Fax: +49 89 8578-3208

Email: hbaier@neuro.mpg.de


Original publication
Incinur Temizer, Joseph Donovan, Herwig Baier, Julia Semmelhack

A visual pathway for looming-evoked escape in larval zebrafish

Current Biology, 25 June 2015

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

Further reports about: Fish Max Planck Institute Neurobiology Zebrafish fish larvae ganglion cells larvae stimulus

More articles from Life Sciences:

nachricht Bolstering fat cells offers potential new leukemia treatment
17.10.2017 | McMaster University

nachricht Ocean atmosphere rife with microbes
17.10.2017 | King Abdullah University of Science & Technology (KAUST)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

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...

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

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

Neutrons observe vitamin B6-dependent enzyme activity useful for drug development

17.10.2017 | Life Sciences

NASA finds newly formed tropical storm lan over open waters

17.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>