Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Seeing on the Quick: New Insights into Active Vision in the Brain

15.08.2018

Tübingen neuroscientists expand on role of superior colliculus – disregarded area in brainstem processes visual stimuli on its own

Eye movements are controlled by a small, centrally located area in the brainstem, the superior colliculus (“small upper hill”). A team of neuroscientists at the University of Tübingen headed by Prof Z. Hafed (Werner Reichardt Centre for Integrative Neuroscience – CIN/Hertie Institute for Clinical Brain Research – HIH) has recently found clear evidence that this brain area not only controls eye movements, but also processes visual input on its own. This brain area processes coarse image regions common to our natural environment especially quickly, and therefore facilitates efficient orienting behaviour in real-world situations.


Clouds, lake, and mountainside are the low spatial frequency parts of the scene. The superior colliculus lets gaze travel efficiently across these features (yellow), relegating the leafy, high-frequency foreground for later inspection.

Photo: Ziad Hafed

“The way that the superior colliculus processes visual input from our surroundings is specifically tuned to what we need to efficiently orient ourselves”, Professor Ziad M. Hafed introduces his object of study. The leader of a research team at the CIN and HIH has been investigating the primate visual system for years.

In primates – and thus in us humans –, conscious seeing is primarily jumpstarted in the visual cortex, a well-known area of the cerebral cortex. But based on their own earlier studies, Hafed’s research group was convinced that the “small upper hill” in the brainstem maintains very important visual functions as well.

For instance, it plays a paramount role in the visual system of fish and amphibians. In mammals and especially in primates, however, this brain area has been thought to mostly just control eye movements and attention.

But Hafed and his team are convinced that the superior colliculus plays a central role in visually-driven environmental orientation and navigation as a whole. “If a brain area controls eye movements, then it seems intuitive that it also fulfills important functions in general orienting behaviour”, Hafed puts it, adding: “But to do so, it must also be able to process visual information.”

To investigate this hypothesis, the Hafed lab performed neurophysiological experiments with rhesus macaques, whose visual system is very similar to our own. The researchers investigated how individual brain cells (neurons) responded to different visual stimuli. Would changes in features such as the image’s orientation, its contrast and background, and other image properties make a difference in how superior colliculus neurons responded?

If this area is responsible for spatial orientation, neurons here must respond especially quickly to those stimuli towards which we would need to direct our attention first. In natural environments, our attention is primarily focused on the most general features first: is there an open space in front of us, are there obstacles, is there a figure or a face? In order for us to cope with our surroundings, our brain must process such features as quickly as possible; fine details can wait for closer inspection.

For this reason, the researchers observed how the neurons they were investigating responded to coarse image features with low amounts of variation in visual information – or (as the scientists call it) with low spatial frequency. This might be the case with large swathes of forest or sky or clouds in our surroundings.

The result: neurons in the superior colliculus do in fact respond to visual stimuli with low spatial frequency the quickest. Naturally, the observed set of neurons did not all respond identically, some going so far as to show a stronger overall response to high spatial frequency stimuli.

But even these high-frequency specialists still responded more quickly to the presentation of coarse image patches: the “turbo boosting” of neural responses to low-frequency stimuli took priority over actually sensing the image content itself. This is important, as the turbo-boosted signal was also instrumental in determining how efficiently eye movements are made.

Thus, the “little hill” in our brain has the ability to analyse visual patterns – a capability most scientists would have denied this brain area could have. “We have added evidence that the primate superior colliculus is not merely an organ of motor control,” says Hafed, “but a visual structure that may be just as important as the primary visual cortex in allowing us to function in our everyday surroundings.”

Wissenschaftliche Ansprechpartner:

Prof. Dr. Ziad M. Hafed
Werner Reichardt Centre for Integrative Neuroscience (CIN)
Otfried-Müller-Str. 25
72076 Tübingen
Germany
Phone: +49 (0)7071 29-88819
ziad.m.hafed@cin.uni-tuebingen.de

Originalpublikation:

Chen, C. -Y., Sonnenberg, L., Weller, S., Witschel, T., & Hafed, Z. M. (2018). Spatial frequency sensitivity in macaque midbrain. Nature Communications, 9: 2852.
doi: 10.1038/s41467-018-05302-5.
Chen, C. -Y. & Hafed, Z. M. (2018). Orientation and contrast tuning properties and temporal flicker fusion characteristics of primate superior colliculus neurons. Frontiers in Neural Circuits (Special Research Topic on The Superior Colliculus/Tectum: Cell Types, Circuits, Computations, Behaviors), 12:58. doi: 10.3389/fncir.2018.00058

Antje Karbe | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-tuebingen.de/

More articles from Life Sciences:

nachricht Russian scientists show changes in the erythrocyte nanostructure under stress
22.02.2019 | Lobachevsky University

nachricht How the intestinal fungus Candida albicans shapes our immune system
22.02.2019 | Exzellenzcluster Präzisionsmedizin für chronische Entzündungserkrankungen

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: (Re)solving the jet/cocoon riddle of a gravitational wave event

An international research team including astronomers from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has combined radio telescopes from five continents to prove the existence of a narrow stream of material, a so-called jet, emerging from the only gravitational wave event involving two neutron stars observed so far. With its high sensitivity and excellent performance, the 100-m radio telescope in Effelsberg played an important role in the observations.

In August 2017, two neutron stars were observed colliding, producing gravitational waves that were detected by the American LIGO and European Virgo detectors....

Im Focus: Light from a roll – hybrid OLED creates innovative and functional luminous surfaces

Up to now, OLEDs have been used exclusively as a novel lighting technology for use in luminaires and lamps. However, flexible organic technology can offer much more: as an active lighting surface, it can be combined with a wide variety of materials, not just to modify but to revolutionize the functionality and design of countless existing products. To exemplify this, the Fraunhofer FEP together with the company EMDE development of light GmbH will be presenting hybrid flexible OLEDs integrated into textile designs within the EU-funded project PI-SCALE for the first time at LOPEC (March 19-21, 2019 in Munich, Germany) as examples of some of the many possible applications.

The Fraunhofer FEP, a provider of research and development services in the field of organic electronics, has long been involved in the development of...

Im Focus: Regensburg physicists watch electron transfer in a single molecule

For the first time, an international team of scientists based in Regensburg, Germany, has recorded the orbitals of single molecules in different charge states in a novel type of microscopy. The research findings are published under the title “Mapping orbital changes upon electron transfer with tunneling microscopy on insulators” in the prestigious journal “Nature”.

The building blocks of matter surrounding us are atoms and molecules. The properties of that matter, however, are often not set by these building blocks...

Im Focus: University of Konstanz gains new insights into the recent development of the human immune system

Scientists at the University of Konstanz identify fierce competition between the human immune system and bacterial pathogens

Cell biologists from the University of Konstanz shed light on a recent evolutionary process in the human immune system and publish their findings in the...

Im Focus: Transformation through Light

Laser physicists have taken snapshots of carbon molecules C₆₀ showing how they transform in intense infrared light

When carbon molecules C₆₀ are exposed to an intense infrared light, they change their ball-like structure to a more elongated version. This has now been...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Global Legal Hackathon at HAW Hamburg

11.02.2019 | Event News

The world of quantum chemistry meets in Heidelberg

30.01.2019 | Event News

Our digital society in 2040

16.01.2019 | Event News

 
Latest News

JILA researchers make coldest quantum gas of molecules

22.02.2019 | Physics and Astronomy

Understanding high efficiency of deep ultraviolet LEDs

22.02.2019 | Materials Sciences

Russian scientists show changes in the erythrocyte nanostructure under stress

22.02.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>