Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fight or flight – the zebrafish's eye decides

19.09.2014

The eye of a zebrafish larva can already distinguish between prey and predator

Red or green? Small or large? Fast or slow? Humans and animals rely on their visual organs to classify objects in their environment. Decisions about how we best respond to moving objects in our environment are often made very quickly and unconsciously. The size of a moving object is obviously an important criterion.


Small and large objects activate various circuits in the visual system of zebrafish larvae. This separation begins in the eye and probably decides the direction of the swimming behaviour.

© Max Planck Institute for Medical Research

The rapid speed of a response suggests that specialised neural circuits in the visual system are responsible for recognising important object properties. If they are activated, they trigger the "fight" or "flight" signal in the brain. Scientists at the Max Planck Institute for Medical Research in Heidelberg have now shed light on how such circuits, which are likely to be crucial in classifying objects by size, function in the brain of the zebrafish larva.

How does the brain decide which things in our complex environment require an immediate response from us? A key question in the animal kingdom is: "Is the object moving in my environment prey or predator?" - a question that requires a quick answer in an emergency. Evidently, the visual system manages to detect objects from the constantly changing distribution of light stimuli on the retina based on simple criteria and, if necessary, mobilise a rapid response directly. The basic mechanisms of object classification can be studied using zebrafish larva as the model system.

The larva's well-developed visual system allows it to catch small prey and avoid larger objects. The decision about whether the larva approaches or avoids the object is made on the basis of size. Researchers working with Johann Bollmann at the Max Planck Institute in Heidelberg have now been able to demonstrate that small and large stimuli, which trigger swimming movements in different directions, generate neural activity in neighbouring but different circuits in the fish's brain. The behaviour-related distinction in size thus begins in the ganglion cells of the eye.

The retina in the eye contains a variety of different ganglion cells which respond specifically to colour, size, movement or contrast, for example. However, little is understood about how these different messages travel via the optic nerve to the brain and are processed. The researchers were now able to identify such cells in a central area of the fish's brain - the tectum. These cells respond specifically to those object sizes that correspond to a small prey or a large troublemaker in the world of the zebrafish larva.

It turns out that the nerve endings of ganglion cells, which project into the tectum, respond differently to object size. Other cell types downstream in the tectum distinguish between small and large objects on the zebrafish's magnitude scale in their activity patterns, depending on the layer in which they receive their synaptic inputs.

"This suggests that the size classification process begins in the retina of the eye to subsequently classify the object that is seen in the tectum into the categories of 'small enough to count as prey' or 'sufficiently large to watch out for'. The fish larva then adapts its behaviour accordingly," says Johann Bollmann from the Max Planck Institute for Medical Research. The brains of mammals contain very similar structures that are crucially involved in the visual control of such targeted movements. This suggests that the functions of detecting objects and controlling actions are resolved in a similar way as they are in the small brain of the fish larva. 

Contact 

Original publication

 
Stephanie J. Preuss, Chintan A. Trivedi, Colette M. vom Berg-Maurer, Soojin Ryu, Johann H. Bollmann
Classification of object size in retinotectal microcircuits
Current Biology, 19 September 2014

Johann H. Bollmann | Max-Planck-Institute
Further information:
http://www.mpg.de/8416636/zebrafish-eye

Further reports about: Max Planck Institute Zebrafish activity ganglion cells larva stimuli visual system

More articles from Life Sciences:

nachricht The birth of a new protein
20.10.2017 | University of Arizona

nachricht Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

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

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>