Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Car or pedestrian – How we can follow objects with our eyes

02.10.2008
When an object moves fast, we follow it with our eyes: our brain correspondingly calculates the speed of the object and adapts our eye movement to it. This in itself is an enormous achievement, yet our brain can do even more than that.

In the real world, a car will typically accelerate or brake faster than, say, a pedestrian. But the control of eye movement in fact responds more sensitively to changes in the speed of fast moving objects than slow moving objects.

"Gain control" is the name for this phenomenon, which has been known for some time now, but which has now just been recently analyzed more closely by a group working with associate professor Dr. Stefan Glasauer from the Bernstein Center for Computational Neuroscience and Ludwig-Maximilians-Universität (LMU) München. The researchers determined the location in the brain where gain control is calculated, and what neuronal networks are behind this complex process. The results were postulated in a mathematical model and experimentally verified – and could be of great help in the diagnosis of eye movement disorders.

Eye movement control is not exactly a new field of research. We already know, for example, that different regions of the cerebral cortex are involved in eye tracking movements. These include "Area MST" and the so-called frontal eye fields, or FEFs for short. Nerve cells in Area MST mainly reflect the speed of the eye or target motion, whereas cells in the FEFs mainly respond to changes in speed. These insights have been obtained mostly from human behavioral experiments and from neurophysiological studies.

But the aim of the scientists under the direction of Glasauer, his coworker Ulrich Nuding and Professor Ulrich Büttner of the Neurological Clinic at LMU Munich was now to amalgamate these insights into a computer model that actually explains this eye movement control. The new model simulates the most important circuits required for controlling eye tracking movement. In Area MST, the speed of the target object is calculated and compared with the momentary eye speed in order to adapt it accordingly. The FEFs are the actual location where the gain control takes place; this is where the sensitivity of eye movement to changes in speed is defined.

In order to verify their models in studies, the scientists joined forces with colleagues at University College in London: they had subjects follow a dot on a screen with their eyes. The activity of the FEFs was briefly disrupted by so-called "transcranial magnetic stimulation". This technology can influence individual, targeted areas of the brain for a few seconds. The experiments did indeed confirm the predictions of the models: as long as the observed object was moving at a constant speed, a disruption of the FEFs had little effect on eye movement control.

The sensitivity of the eye movement to changes in speed, on the other hand, did not increase sufficiently at higher speeds when the FEFs were disrupted. It follows that the gain control is determined in the FEFs depending on the speed of the eye or the target. In short, the faster an object moves, the greater the adaptability. "With this, we have managed for the first time to explain the purpose of parallel anatomic paths in neuronal processing for eye tracking," says Glasauer. Sensitivity control also exhibits interesting parallels to visual attention control, for which the FEFs are also important. Therefore, it can very well be regarded as an attention mechanism within the eye tracking system.

Kathrin Bilgeri | alfa
Further information:
http://www.lmu.de
http://www.en.uni-muenchen.de/news/research/index.html

More articles from Life Sciences:

nachricht Cnidarians remotely control bacteria
21.09.2017 | Christian-Albrechts-Universität zu Kiel

nachricht Immune cells may heal bleeding brain after strokes
21.09.2017 | NIH/National Institute of Neurological Disorders and Stroke

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Comet or asteroid? Hubble discovers that a unique object is a binary

21.09.2017 | Physics and Astronomy

Cnidarians remotely control bacteria

21.09.2017 | Life Sciences

Monitoring the heart's mitochondria to predict cardiac arrest?

21.09.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>