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 Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Global study of world's beaches shows threat to protected areas

19.07.2018 | Earth Sciences

New creepy, crawly search and rescue robot developed at Ben-Gurion U

19.07.2018 | Power and Electrical Engineering

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>