Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How we keep track of what matters

23.02.2016

The visual system keeps track of relevant objects even as eye movements are made, shows a study by the German Primate Center

When watching basketball, we are easily able to keep track of the ball while also making frequent eye and head movements to look at the different players. Neuroscientists Tao Yao, Stefan Treue and B. Suresh Krishna from the German Primate Center (DPZ) in Göttingen, Germany, wanted to understand the neural mechanisms that allow us to see a stable world and keep track of relevant objects even without directly looking at them and when we shift our gaze.


When watching basketball, we are easily able to keep track of the ball while also making frequent eye and head movements to look at the different players. Image: Monkey Business Images/ Fotolia

Their study shows that the rhesus macaque’s brain “marks” relevant visual objects and rapidly updates the position of these markers as the monkey looks around. Since humans and monkeys exhibit very similar eye-movements and visual function, these findings are likely to generalize to the human brain. These results are also likely to be important for our understanding of disorders like schizophrenia, visual neglect and other attention deficit disorders (PLOS Biology).

The light that enters the eye falls onto the retina, where it is converted into neural activity that is then used by the brain to provide our sense of vision. The central part of the retina, the fovea, is specialized for more sensitive, higher-definition vision. It is therefore advantageous when viewing a scene, to move the eye so that it is centered successively (or fixated) on each important part of the scene, and light from these parts can fall onto the fovea and be analyzed in greater detail.

Indeed, both humans and monkeys make two to three fast eye movements every second in this manner, with each eye-movement lasting less than one-tenth of a second. Because the eye acts like a camera, each eye-movement results in a different view of the scene falling onto the retina.

However, despite these fast changes in viewpoint (which can also result from head movements), humans and monkeys do not see a scene that jumps around: Instead, they are able to “stitch together” the information obtained during each fixation to perceive a stable visual scene. They are also able to keep track of where relevant objects are in the scene even with these frequent changes in viewpoint. This is a very challenging task. Visual neurons respond more to relevant objects than to irrelevant ones. This increased response to relevant stimuli “marks” relevant stimuli.

Since each visual neuron in the brain only responds when a specific part of the retina is stimulated, each change in viewpoint with an eye-movement results in a different group of neurons being activated by a given visual stimulus before and after the eye-movement. This means that the “marking”, i.e. the information about which objects are relevant, needs to be transferred between different groups of neurons, so that after the eye-movement, these relevant objects continue to evoke larger responses and the brain can keep track of them. However, very little was known about the properties of such an information transfer in the brain, or even about whether it occurred at all.

In order to address this, neuroscientists Tao Yao, Stefan Treue and Suresh Krishna of the German Primate Center (DPZ) examined the responses of many single neurons in the brain of two monkeys while they attended to a stimulus without directly looking at it and made an eye-movement while maintaining attention on this stimulus.

To measure the activity of single neurons, the scientists inserted electrodes thinner than a human hair into the monkey’s brain and recorded the neurons’ electrical activity. Because the brain is not pain-sensitive, this insertion of electrodes is painless for the animal. By recording from single neurons in an area of the monkey’s brain known as area MT, the scientists were able to show that a transfer of information about the locations of relevant objects indeed occurs. However, no information is transferred about what the relevant objects look like.

“Our study shows how the primate brain is able to keep track of attended objects while ignoring irrelevant ones”, says Tao Yao, first author of the publication. It supports the idea that the brain maintains markers to attended stimuli and updates the locations of these markers with each eye-movement.

“Our results answer several important questions about how our brains see a stable visual world despite frequent intervening eye-movements. Also, because the updating of attentional markers is known to be impaired in schizophrenia, visual neglect and other attention deficit disorders, our results may help improve our understanding of these diseases”, Tao Yao comments on the findings.

Original publication
Tao Yao, Stefan Treue and B. Suresh Krishna: An attention-sensitive memory trace in macaque MT following saccadic eye movements. PLOS Biology.

Contact
Dr. Dr. med. Suresh Krishna
Tel: +49 551 3851-354
E-mail: skrishna@dpz.eu

Dr. Susanne Diederich (Communication)
Tel: +49 551 3851-359
E-mail: sdiederich@dpz.eu

Printable Images
Printable images are provided by the DPZ’s public relations department or may be downloaded from the photo database of our website. In case of publication, please send a copy or a link as reference.

The German Primate Center (DPZ) in Göttingen, Germany, conducts basic research on and with primates in the areas of infectious diseases, neurosciences and organismic biology. In addition, it operates four field stations abroad and is a competence and reference center for primate research. The DPZ is one of the 88 research and infrastructure institutions of the Leibniz Association in Germany. www.dpz.eu

Weitere Informationen:

http://medien.dpz.eu/webgate/keyword.html?currentContainerId=3142

Dr. Susanne Diederich | idw - Informationsdienst Wissenschaft

Further reports about: Leibniz-Institut disorders markers monkeys neurons stimulus

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>