Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Faster fish thanks to nMLF neurons

25.07.2014

Scientists discover the transmission used by zebrafish to change to another gear

As we walk along a street, we can stroll at a leisurely pace, walk quickly, or run. The various leg movements needed to do this are controlled by special neuron bundles in the spinal cord. It is not quite clear how these central pattern generators know how quickly the legs are to be moved.


Looking into the brain of a zebrafish larva. The neurons in the retina (green) send their signals from the eyes (yellow) to the brain. The cells linking the brain and spinal cord appear in red.

© MPI of Neurobiology / Portugues

An international team working with scientists from Harvard University and the Max Planck Institute of Neurobiology in Martinsried has now discovered individual neurons in the brain of zebrafish larvae that control the animals' swimming speed. Human movements are also controlled by central pattern generators. The results represent an important step in gaining a better understanding of how rhythmic movements are modulated.

As young children, we learn how to place one foot in front of the other at a steady pace. Once this has been learned, small bundles of neurons in the spinal cord - the central pattern generators (CPG) - ensure that this sequence happens almost automatically: we do not need to think about when and how far away we should place our foot down when we take each step. Once they are operational, the CPG neurons do not need any further stimulus to transmit their impulses. But how are these cells stimulated, and how does the brain tell them how quickly the legs need to be moved?

Ruben Portugues and his colleagues have studied zebrafish larvae to investigate how the brain and the CPGs are connected. The animals use various methods to increase their speed: they can beat their tails for longer periods of time, move the tail to and fro more vigorously, reduce the time between periods of tail movements such that these periods called bouts happen more frequently or switch to a completely different movement rhythm or gait - like a horse that changes from a trot to a gallop.

To understand how the brain triggers these various types of swimming movements, the neurobiologists concentrated on a group of around 20 neurons which send out their extensions from the midbrain to the spinal cord. The scientists already knew that the cells in this nMLF region are active during swimming. They were now able to show that stimulating these cells triggered swimming movements. As the researchers now report in the journal Neuron, the cells in the central pattern generator receive the initial stimulus for a movement from neurons in the nMLF region. They also discovered that it is almost impossible for the fish to regulate their swimming speed if four particular nMLF cells are switched off.

Calcium-sensitive dyes can be used to image neuronal activity. As zebrafish larvae are transparent, the scientists were able to observe the activity of individual nMLF cells directly through the microscope. "It was especially exciting when the animals changed their speed," reports Ruben Portugues, who was recently appointed Leader of a Research Group at the Max Planck Institute of Neurobiology. "We had actually expected that more nMLF cells would simply be activated simultaneously to enable the fish to swim faster."

Instead, the scientists discovered that neurons which were already active became even more active when swimming faster. "We don't yet know the details of how a higher level of activity leads to faster movements," says Portugues. However, the scientists can demonstrate that individual nMLF cells, known as MeLR cells, control the length of swimming periods and MeLc cells, as they are known, control the frequency to the tail beating. To date, scientists were aware of the nMLF region and its cells, but nobody knew what they control or how they do it. "Now that we have found the transmission, as it were, for the swimming movements, the next question to be answered is how and where the brain decides what gear it wants to engage," says Ruben Portugues, summing up the next challenge.

Contact 

Dr. Stefanie Merker

Max Planck Institute of Neurobiology, Martinsried

Phone: +49 89 8578-3514

 

Dr. Ruben Portugues

Max Planck Research Group

Max Planck Institute of Neurobiology, Martinsried

Phone: +49 89 8578-3492

 

Original publication

 
Kristen Severi*, Ruben Portugues*, Joao Marques, Donald O'Malley, Michael Orger, Florian Engert (*equal contribution)
Neural control and modulation of swimming speed in the larval zebrafish
Neuron, 24 July 2014

Dr. Stefanie Merker | Max-Planck-Institute

Further reports about: Neurobiology activity animals larvae movements neurons spinal swimming tail zebrafish

More articles from Life Sciences:

nachricht MACC1 Gene Is an Independent Prognostic Biomarker for Survival in Klatskin Tumor Patients
31.08.2015 | Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft

nachricht Fish Oil-Diet Benefits May be Mediated by Gut Microbes
28.08.2015 | University of Gothenburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Increasingly severe disturbances weaken world's temperate forests

Longer, more severe, and hotter droughts and a myriad of other threats, including diseases and more extensive and severe wildfires, are threatening to transform some of the world's temperate forests, a new study published in Science has found. Without informed management, some forests could convert to shrublands or grasslands within the coming decades.

"While we have been trying to manage for resilience of 20th century conditions, we realize now that we must prepare for transformations and attempt to ease...

Im Focus: OU astrophysicist and collaborators find supermassive black holes in quasar nearest Earth

A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.

The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...

Im Focus: What would a tsunami in the Mediterranean look like?

A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).

Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...

Im Focus: Self-healing landscape: landslides after earthquake

In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.

These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ...

Im Focus: FIC Proteins Send Bacteria Into Hibernation

Bacteria do not cease to amaze us with their survival strategies. A research team from the University of Basel's Biozentrum has now discovered how bacteria enter a sleep mode using a so-called FIC toxin. In the current issue of “Cell Reports”, the scientists describe the mechanism of action and also explain why their discovery provides new insights into the evolution of pathogens.

For many poisons there are antidotes which neutralize their toxic effect. Toxin-antitoxin systems in bacteria work in a similar manner: As long as a cell...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Networking conference in Heidelberg for outstanding mathematicians and computer scientists

20.08.2015 | Event News

Scientists meet in Münster for the world’s largest Chitin und Chitosan Conference

20.08.2015 | Event News

Large agribusiness management strategies

19.08.2015 | Event News

 
Latest News

Production research by Fraunhofer IAO honored with three awards at the ICPR 2015

31.08.2015 | Awards Funding

Single-Crystal Phosphors Suitable for Ultra-Bright, High-Power White Light Sources

31.08.2015 | Materials Sciences

Manchester Team Reveal New, Stable 2D Materials

31.08.2015 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>