Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New slant on vision research: Neurons sensitive to viewing angle

03.03.2005


Mistakes made by human subjects in identifying the facing direction of faces, cars or meaningless objects have yielded evidence that the brain contains nerve cells, or neurons, whose job is to encode the viewing angle of objects. It is well known that certain neurons respond to color, motion, edges and other aspects of our environment. Now, University of Minnesota researchers have found that our visual cortex contains neurons that tell us, for example, whether a face is turned in our direction or not. The work adds to knowledge of how the brain collects and processes visual information leading to the recognition of objects, and it may inform the design of machine vision. The study will be published in the March 3 issue of the journal Neuron.

The brain relies on millions of neurons to report the visual elements of our environment. But, for example, if every neuron geared to motion fired in response to any motion whatsoever, then we couldn’t tell whether a train was chugging into the distance or bearing down on us. Instead, to gain a complete picture of the world, our brains appear to contain separate, but physically intertwined, populations of neurons that respond to only one small aspect of our environment. The brain then bases its interpretation of images largely on which neurons fire.

"The issue is, what is the underlying neural mechanism that supports the ability to recognize objects viewed from different angles?" said Sheng He, associate professor of psychology, who directed the study. "This study supports the idea that we have explicit representations in our brains for specific views of objects." The study was carried out jointly with Fang Fang, a graduate student in He’s laboratory.



The researchers presented volunteers with the image of a face, a car or a meaningless geometric object on the computer. In each case, the first image--called the adapting image--was turned to one side. After a very brief pause, another image of the same face or object--called the test image--was flashed on the screen. But this time, the image was either head-on or turned very slightly (three or six degrees) to one side or the other. Whatever the orientation of the test image, subjects were required to choose whether it was turned to the right or the left.

When subjects were presented with an adapting image turned 30 degrees to one side, then tested with an image of the same thing in head-on view, they tended to say the test image was tilted in the opposite direction of the adapting image. That is, if they first saw the face of a man turned 30 degrees to the left, then saw his face head-on, they said the face was turned to the right. This "adaptation effect" occurred 80 percent of the time; normally, responses for both directions would be equally likely. Even if the test image was turned three degrees in the same direction as the adapting image, the subjects guessed wrong half the time, saying the test image was turned in the other direction.

The reason for the errors is that when a person stares at an image, neurons that respond to the viewing angle of the image get "tired" and become less responsive when a very similar image is presented again, He said. The brain interprets this lack of response as the object not being turned in the direction the neurons are attuned to. This suggests that there are separate populations of neurons, each responding to a particular narrow range of orientations. The neurons are likely located in the lateral occipital cortex, an area of the cerebral cortex very far back on either side of the head.

The researchers also performed experiments that suggested that for faces, at least, subjects were not deciding the orientation of test images based on "local" features such as noses. When subjects saw unorganized fragments of faces--as if parts of the face were simply erased--as adapting images, no adaptation effect occurred.

"This shows that fragmented local features are not sufficient to get the adaptation effect," He said. "You must have a global representation of the face. But local features may be important within the context of a [complete] face.

"Also, if you adapt to a face, then test with an image of a car, you don’t get adaptation. So local features that identify the object as a face or a car are important. Researchers think there are populations of neurons that respond to classes of objects in the environment, for example, houses, hills, tools, faces and so forth."

The researchers next plan to put volunteers in a functional magnetic resonance imaging scanner and see how different neurons respond to different views of objects. The work was supported by the James S. McDonnell Foundation, the National Institutes of Health and the University of Minnesota.

Sheng He | EurekAlert!
Further information:
http://www1.umn.edu/twincities/index.php

More articles from Studies and Analyses:

nachricht The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung

nachricht A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Scientists spin artificial silk from whey protein

X-ray study throws light on key process for production

A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Breaking the optical bandwidth record of stable pulsed lasers

24.01.2017 | Physics and Astronomy

Choreographing the microRNA-target dance

24.01.2017 | Life Sciences

Spanish scientists create a 3-D bioprinter to print human skin

24.01.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>