Featured Research

from universities, journals, and other organizations

Eyes on the prey: Researchers analyse the hunting behaviour of fish larvae in virtual reality

Date:
May 22, 2013
Source:
Max-Planck-Gesellschaft
Summary:
Moving objects attract greater attention -- a fact exploited by video screens in public spaces and animated advertising banners on the Internet. For most animal species, moving objects also play a major role in the processing of sensory impressions in the brain, as they often signal the presence of a welcome prey or an imminent threat. Scientists have now investigated how the brain uses the information from the visual system for the execution of quicker movements.

(A) A cell type in the tectum, made visible using a green fluorescent protein, highlights the layering of this visual centre. (B) The same cell type as in (A), but labeled with a calcium-sensitive protein.
Credit: © Gabriel; Bollmann; modified from Neuron 76, 1147-1160 (2012).

Moving objects attract greater attention -- a fact exploited by video screens in public spaces and animated advertising banners on the Internet. For most animal species, moving objects also play a major role in the processing of sensory impressions in the brain, as they often signal the presence of a welcome prey or an imminent threat. This is also true of the zebrafish larva, which has to react to the movements of its prey. Scientists at the Max Planck Institute for Medical Research in Heidelberg have investigated how the brain uses the information from the visual system for the execution of quicker movements. The animals' visual system records the movements of the prey so that the brain can redirect the animals' movements through targeted swim bouts in a matter of milliseconds. Two hitherto unknown types of neurons in the mid-brain are involved in the processing of movement stimuli.

In principle, the visual system of zebrafish larvae resembles that of other vertebrates. Moreover, its genome has been decoded, it is a small organism, and it has transparent skin, which is easily penetrated by light in the fluorescent microscope. Therefore, these animals are very suitable for studying visual motion perception. They also display very clear prey capture behaviour. With the help of their finely-tuned visual system, they pursue and catch small ciliates. To do this, they execute a series of swimming manoeuvres in a matter of one or two seconds, during which they repeatedly verify the direction and distance of the prey so that they can adapt their subsequent movement steps. The larva's brain must, therefore, filter and evaluate visual information extremely rapidly so that it can select appropriate motor patterns.

Using high-speed video recordings, researchers working with Johann Bollmann at the Max Planck Institute for Medical Research began by studying the natural course of prey capture by the larvae under a variety of starting conditions. It emerged that the larvae repeatedly execute a basic motion pattern and can apply an orientation component that re-directs the hunter towards the prey with each bout of swimming. To do this, the larvae must process visual information in just a few hundreds of milliseconds.

Using an innovative experimental design, the scientists then modelled, in a second step, the natural swimming environment as a "virtual reality," in which the larvae execute typical prey capture sequences without actually moving. The virtual prey consisted of computer-controlled images, which were projected onto a small screen. In this way, the role of motion parameters, for example the size and speed of the "prey," could be studied quantitatively in relation to the processing of visual stimuli by the animals.

In the "virtual reality," the scientists can test how the fish larvae respond to unexpected shifts in the prey after a swim bout. "When we direct our gaze at a target through movements of our eyes and head, we expect the object to appear in a central position in our field of view. In the larvae, very slight deviations from the target position or delays in the re-appearance of the virtual prey increased the reaction times. When it receives unexpected visual feedback, the larva's brain presumably needs extra processing time to calculate the next swim bout," explains Johann Bollmann from the Max Planck Institute in Heidelberg.

In addition, with the help of fluorescent microscopes, the researchers can examine the activity of groups of neurons in the larval brain which are likely to control the targeted prey capture movements. In a previous study, they discovered cell types that react specifically to opposing directions of movement. These previously unknown neurons in the dorsal region of the midbrain (tectum) differ in their directional sensitivity and in the structure of their finely branched projections. "It appears that different directions of motion are processed in different layers of the tectum, since the dendritic ramifications of these cell types are spatially separated from each other," says Bollmann.


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal References:

  1. Chintan A. Trivedi, Johann H. Bollmann. Visually driven chaining of elementary swim patterns into a goal-directed motor sequence: a virtual reality study of zebrafish prey capture. Frontiers in Neural Circuits, 2013; 7 DOI: 10.3389/fncir.2013.00086
  2. Jens P. Gabriel, Chintan A. Trivedi, Colette M. Maurer, Soojin Ryu, Johann H. Bollmann. Layer-Specific Targeting of Direction-Selective Neurons in the Zebrafish Optic Tectum. Neuron, 2012; 76 (6): 1147 DOI: 10.1016/j.neuron.2012.12.003

Cite This Page:

Max-Planck-Gesellschaft. "Eyes on the prey: Researchers analyse the hunting behaviour of fish larvae in virtual reality." ScienceDaily. ScienceDaily, 22 May 2013. <www.sciencedaily.com/releases/2013/05/130522112006.htm>.
Max-Planck-Gesellschaft. (2013, May 22). Eyes on the prey: Researchers analyse the hunting behaviour of fish larvae in virtual reality. ScienceDaily. Retrieved August 27, 2014 from www.sciencedaily.com/releases/2013/05/130522112006.htm
Max-Planck-Gesellschaft. "Eyes on the prey: Researchers analyse the hunting behaviour of fish larvae in virtual reality." ScienceDaily. www.sciencedaily.com/releases/2013/05/130522112006.htm (accessed August 27, 2014).

Share This




More Plants & Animals News

Wednesday, August 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Firefighters Rescue Puppy Stuck in Tire

Raw: Firefighters Rescue Puppy Stuck in Tire

AP (Aug. 26, 2014) — It took Houston firefighters more than an hour to free a puppy who got its head stuck in a tire. (Aug. 26) Video provided by AP
Powered by NewsLook.com
Have You Ever Been 'Sleep Drunk?' 1 in 7 Has

Have You Ever Been 'Sleep Drunk?' 1 in 7 Has

Newsy (Aug. 26, 2014) — A study published in the journal "Neurology" interviewed more than 19,000 people and found 15 percent suffer from being "sleep drunk." Video provided by Newsy
Powered by NewsLook.com
Great White Shark Spotted Off Massachusetts Coast

Great White Shark Spotted Off Massachusetts Coast

Reuters - US Online Video (Aug. 26, 2014) — A great white shark is spotted off the shore at Duxbury beach in Massachusetts forcing beach goers out of the water. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Raw: Elk Wanders Into German Office Building

Raw: Elk Wanders Into German Office Building

AP (Aug. 25, 2014) — A young bull elk wandered inside the office building of a company in Dresden, Germany on Monday. The elk became trapped between a wall and glass windows while rescue workers tried to rescue him safely. (Aug. 25) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:  

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile iPhone Android Web
    Follow Facebook Twitter Google+
    Subscribe RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins