Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

RUB Scientists visualize simultaneous encoding of object orientation and its motion

24.03.2011
Nerve cell networks transform different information into overlaid activity patterns

Imagine sitting in a train at the railway station looking outside: Without analyzing the relative motion of object contours across many different locations at the same time, it is often difficult to decide whether it’s your train that starts moving, or the one at the opposite track. How are these diverse information conveyed simultaneously through the network of millions of activated nerve cells in the visual brain? “Neurons synchronize with different partners at different frequencies” says Dr. Dirk Jancke, Neuroscientist at the Ruhr-University in Bochum, Germany.


Visualization of how the primary visual cortex encodes both orientation and retinotopic motion of a visual object simultaneously. As a visual stimulus the scientists used a horizontal grating moving downwards on a monitor screen (sketched at most right). From left to right: The brain’s vascular surface and a 20 millisecond camera snapshot of brain activity. Dark regions represent domains in which nerve cells are active which encode the horizontal grating orientation (see pattern of red outlines). At the same time, overlaid on this patchy map, a traveling activity wave was observed moving downwards across the brain (red represents peak activity, blue depicts low amplitude). The wave thus represented the actual movement of the grating stripes independently from the orientation encoding pattern.

A new imaging technique enabled to show that such functioning results in distinct activity patterns overlaid in primary visual cortex. These patterns individually signal motion direction, speed, and orientation of object contours within the same network at the same time. Together with colleagues at the University of Osnabrück, the Bochum scientists successfully visualized such brain multiplexing using a modern real-time optical imaging method that exploits a specific voltage-sensitive dye.

Imaging with voltage-sensitive dye: A method to capture real-time brain dynamics

The dye incorporates in the brain cells’ membrane and changes fluorescence whenever these receive or send electrical signals. Hence, high resolution camera systems allow to simultaneously capture activities of millions of nerve cells across several square millimeters across the brain.

First-time visualization of grating pattern motion across the brain surface

As a stimulus the researchers used simple oriented gratings with alternating black-white stripes drifting at constant speed across a monitor screen. These stimuli have been used for more than 50 years in visual neuroscience and still are conventionally applied in medical diagnostics. However, brain activity that signals both the grating’s orientation and its motion simultaneously has not been detected so far. Such signals could now be demonstrated for the first time. Note that further computational steps including sophisticated analysis were needed before those smallest brain activity signals became visible.

Cortical mapping of object orientation

Optical imaging became state-of-the-art since it allows fine grained resolution of cortical pattern activity, so-called maps, in which local groups of active nerve cells represent grating orientation. Thereby, a particular grating orientation activates different groups of nerve cells resulting in unique patchy patterns. Their specific map layout encodes actual stimulus orientation.

Transfer of motion information through overlaid activity waves

Jancke: “Our novel imaging method furthermore captures propagating activity waves across these orientation maps. Hence, we additionally observe gratings moving in real-time across the brain. In this way, motion direction and speed can be estimated independently from orientation maps, which enables resolving ambiguities occurring in visual scenes of everyday life.” The emerging spatial-temporal patterns could then individually be received and interpreted by other brain areas. To give a picture: a radio gets a permanent stream of broadcasts simultaneously. In order to listen to a particular station one has to choose only the channel to tune. For example, a following brain area might preferentially compute an object’s orientation while others process its movement direction or speed simultaneously. In the future, the scientists hope to discover more of the brains real-time action when similar tools are used with increasing stimulus complexity: Naturalistic images are experienced so effortlessly in everyday life. Still it remains an intriguing question how the brain handles such complex data gaining a stable percept every moment in time.

Title Listing

Onat S, Nortmann N, Rekauzke S, König P, Jancke D (2011). Independent encoding of grating motion across stationary feature maps in primary visual cortex visualized with voltage-sensitive dye imaging. Neuroimage 55: 1763-1770. http://dx.doi.org/10.1016/j.neuroimage.2011.01.004

Contact

Dr. Dirk Jancke, Real-time Optical Imaging Group, Institut für Neuroinformatik NB 2/27, Ruhr-Universität Bochum, Universitätstr. 150, D-44780 Bochum, Germany, Tel: +49 234 32 27845, Fax: +49 234 32 14209, E-Mail: jancke@neurobiologie.rub.de, http://homepage.ruhr-uni-bochum.de/Dirk.Jancke/

Dr. Josef König | idw
Further information:
http://www.ruhr-uni-bochum.de/
http://homepage.ruhr-uni-bochum.de/Dirk.Jancke/brain_multiplexing.html

More articles from Life Sciences:

nachricht Navigational view of the brain thanks to powerful X-rays
18.10.2017 | Georgia Institute of Technology

nachricht Separating methane and CO2 will become more efficient
18.10.2017 | KU Leuven

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

Osaka university researchers make the slipperiest surfaces adhesive

18.10.2017 | Materials Sciences

Space radiation won't stop NASA's human exploration

18.10.2017 | Physics and Astronomy

Los Alamos researchers and supercomputers help interpret the latest LIGO findings

18.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>