Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The retina not only ensures sharp, but also stable vision

30.04.2020

Researchers from Tübingen show for the first time that the milliseconds-long blindness that occurs during rapid movements of the eyes, which allows flicker-free vision, comes from the retina.

Anyone who has ever recorded a video knows that the camera must be held still so that the images do not blur. On the other hand, we always perceive a stable image of the world, even though our eyes constantly move back and forth when looking for new impressions and therefore cause shaky images to be projected onto the retina.


Prof. Dr. Ziad M. Hafed

Copyright: Akshay Markanday, 2017

However, because vision is suppressed for milliseconds during these brief eye movements, these blurring motions are not perceived. Professor Ziad M. Hafed and Dr. Thomas Münch and their teams show in the journal Nature Communications that the signal for this suppression comes directly from the retina and its neuronal activity.

Hafed heads the "Active Perception" laboratory at the Hertie Institute for Clinical Brain Research (HIH), is a research group leader at the Werner Reichardt Center for Integrative Neuroscience (CIN) at the University of Tübingen, and a professor at the Faculty of Medicine. Münch is a group leader at the Research Institute for Ophthalmology at the University of Tübingen and at the CIN.

This is the first time that a coherent explanation has been found for the well-known phenomenon of saccadic suppression. Saccade is the term used to describe rapid movements of the eyes. So far, there have been two competing hypotheses about what causes saccadic suppression.

According to the first hypothesis, the suppression starts from the motor signals that also trigger the eye movement. According to the second hypothesis, the suppression is purely visual and caused by the image sequences on the retina.

This means that the blurred images would correct themselves already at the very first stage of vision, the retinal circuit. The results of the researchers show that the retinal hypothesis is indeed correct, but that the motor signal also plays an unexpected role.

Hafed, Münch, and their colleagues based their conclusions on various experiments. Initially, they asked subjects to look at high-resolution, computergenerated images of coarse and fine surfaces, which simulated the properties of natural images.

They faded in short flashes of light of different strengths while the test subjects moved their eyes. Saccadic suppression made subjects unaware of the flashes, unless they were bright enough.

It turned out that the ultrashort blindness was dependent on the displayed image. The suppression was stronger in the images with a coarse texture. It started earlier and lasted longer than in the images with a fine texture. "The fact that the strength and length of the suppression depended on the textures depicted could only mean that the trigger had to be visual," says Hafed.

"We then confirmed this in many other experiments." Among other things, the scientists were able to show that the visual signal is already suppressed when it leaves the eye. “The retina therefore contributes directly to our stable visual impression,” says Münch. "It detects that the world is rushing by and regulates the sensitivity for a short time."

In order to explore the influence of the eye movement trigger itself, the scientists conducted an experiment in which the test subjects either moved their eyes over an object or kept their eyes still while the object was moving.

The image sequences on the retina were the same in both cases, and saccadic suppression occurred in both cases. However, the suppression with real eye movements lasted much shorter.

"We conclude that the movement signal makes a difference in the duration of saccadic suppression," Saad Idrees and Matthias Baumann explain. They are the two doctoral students who carried out the experiments. "So, the movement trigger is still relevant."

The results are also of medical relevance. Maybe they help people who can no longer see their world in a stable way due to illness. “This can be a very stressful symptom, for example in multiple sclerosis or Parkinson's disease,” says Hafed. "Perhaps special computer-controlled glasses can support these patients in the future to straighten the unstable pictures."

Wissenschaftliche Ansprechpartner:

Prof. Dr. Ziad Hafed
Werner Reichardt Center for Integrative Neuroscience at the University of Tübingen
Hertie Institute for Clinical Brain Research
Otfried-Müller-Straße 25
72076 Tübingen
Telefon +49 7071 29-88819
ziad.m.hafed@cin.uni-tuebingen.de

Dr. Thomas Münch
Research Institute for Ophthalmology at the University of Tübingen
Werner Reichardt Center for Integrative Neuroscience at the University of Tübingen
Otfried-Müller-Straße 25
72076 Tübingen
thomas.muench@uni-tuebingen.de

Originalpublikation:

Idrees S., Baumann M.P., Franke F., Münch T.A., Hafed Z.M. (2020): Perceptual saccadic suppression starts in the retina, Nature Communications.
https://doi.org/10.1038/s41467-020-15890-w

Weitere Informationen:

http://www.hih-tuebingen.de Hertie-Institut für klinische Hirnforschung
https://www.uni-tuebingen.de Eberhard Karls Universität Tübingen

Silke Dutz | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht Polarization of Br2 molecule in vanadium oxide cluster cavity and new alkane bromination
13.07.2020 | Kanazawa University

nachricht Researchers present concept for a new technique to study superheavy elements
13.07.2020 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron cryo-microscopy: Using inexpensive technology to produce high-resolution images

Biochemists at Martin Luther University Halle-Wittenberg (MLU) have used a standard electron cryo-microscope to achieve surprisingly good images that are on par with those taken by far more sophisticated equipment. They have succeeded in determining the structure of ferritin almost at the atomic level. Their results were published in the journal "PLOS ONE".

Electron cryo-microscopy has become increasingly important in recent years, especially in shedding light on protein structures. The developers of the new...

Im Focus: The spin state story: Observation of the quantum spin liquid state in novel material

New insight into the spin behavior in an exotic state of matter puts us closer to next-generation spintronic devices

Aside from the deep understanding of the natural world that quantum physics theory offers, scientists worldwide are working tirelessly to bring forth a...

Im Focus: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

 
Latest News

Black phosphorus-based van der Waals heterostructures for mid-infrared light-emission applications

13.07.2020 | Physics and Astronomy

Polarization of Br2 molecule in vanadium oxide cluster cavity and new alkane bromination

13.07.2020 | Life Sciences

Researchers present concept for a new technique to study superheavy elements

13.07.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>