Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study shows how the brain pays attention

24.01.2003


Neural circuits that control eye movements play multiple roles in visual attention



With so many visual stimuli bombarding our eyes -- cars whizzing by, leaves fluttering -- how can we focus attention on a single spot -- a word on a page or a fleeting facial expression? How do we filter so purely that the competing stimuli never even register in our awareness?

A pair of Princeton scientists have found that it has a lot to do with the brain circuits that control eye movements. Neuroscientists Tirin Moore and Katherine Armstrong showed that these brain circuits serve a double function: In addition to programming eye movements, they also trigger amplification or suppression of signals that pour in from the locations where the eyes could move.


The finding, published in the Jan. 23 issue of Nature, is the first to pinpoint a neural mechanism behind one of the most fundamental aspects of mental activity -- the ability to direct attention to one thing as opposed to another.

"Without regulating your attention, you would orient to everything that appears and moves. An organism that couldn’t filter anything just wouldn’t work. It would be in a state of constant distraction," said Moore. "This work shows that, whether we are moving our eyes or not, the networks that control eye movements may be a source of that filtering."

Working with monkeys, the researchers picked a site in the brain area that controls eye movements and established exactly where neurons at that site made the eyes move. They then located a single neuron, in another part of the brain, that was responsible for processing visual stimuli from precisely the same location targeted by neurons at the eye movement site.

With the monkeys trained to fixate on the center of their visual field, the researchers displayed an image in the location associated with the two brain areas. They then electrically stimulated the eye movement neurons, but not strongly enough to actually make the eyes move. When this microstimulation was applied, the visual processing neuron showed a much greater response to the displayed image than when the electrical stimulation was not applied. On the other hand, when no image was being displayed, microstimulation of eye movement neurons had no effect on the visual neuron.

The researchers concluded that the very act of preparing an eye movement to a particular location caused an amplification of signals from that area. These eye movement neurons acted like a volume control on an amplifier, controlling the strength of the signal from one particular spot in space, but not altering the quality of that signal. By stimulating neurons in the eye movement area, the researchers in effect forced the animal to shift its attention from one location to another even though it did not move its eyes.

The study hinges on a long-known fact in visual attention -- that humans and primates can attend to something without moving their eyes to that object. This ability is useful for many animals that encounter social situations in which there is a potential danger in looking directly at another animal. But scientists were unsure how closely eye movements were tied to the phenomenon of attention.

Moore and Armstrong’s finding builds on an earlier study in which Moore observed behavioral effects of electrically stimulating eye movement neurons. In that study, monkeys were better able to detect subtle changes in a visual target when their eye movement neurons had been stimulated. The new study, which measured electrical output of visual neurons rather than measuring a behavioral effect, draws a much more powerful conclusion about how the brain is wired.

Calling the study a "landmark," neuroscientist William Newsome of Stanford University compared the work to discovering how the ignition system of a car is wired. "You know, from looking at the car behaviorally, that if you put the key in the ignition and turn the crank it leads to the car starting," said Newsome. "But if you really want to understand what’s going on inside that car -- if you want to go in there and fix things when they go wrong -- you need to know how that behavior comes to pass. Where does the signal go? And then where does it go from there?"

There are many human diseases and disorders that involve defects in information processing and attention -- most famously attention deficit disorder -- for which scientists would like a firm idea of what neural circuits are involved, said Newsome.

"It takes the whole attention field and steps it up a notch, because now people can start asking questions about mechanisms," said Michael Shadlen, an expert in visual perception at the University of Washington.

Apart from the particular finding about spatial attention, the study reveals an important technique that could be used to trace many other types of neural circuits, the researchers said. "Short-term memory, decision-making, planning motor acts all involve flow of information from one area to another and until now we have had no real way to monitor that information flow or reproduce it in the laboratory," said Newsome.

A next step, said Moore, will be to further analyze the eye movement neurons and find out whether they act alone in regulating spatial attention. Another experiment would be to see whether manipulating these neurons and ostensibly making an animal attend to one place or another can determine what information the animal remembers. "If you don’t attend to something, you don’t see it," Moore said. "There are many things that hit our retinas, but we don’t experience them and don’t remember them unless we pay attention to them."

Steven Schultz | EurekAlert!
Further information:
http://www.princeton.edu/

More articles from Life Sciences:

nachricht Multifunctional bacterial microswimmer able to deliver cargo and destroy itself
26.04.2018 | Max-Planck-Institut für Intelligente Systeme

nachricht ADP-ribosylation on the right track
26.04.2018 | Max-Planck-Institut für Biologie des Alterns

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Why we need erasable MRI scans

New technology could allow an MRI contrast agent to 'blink off,' helping doctors diagnose disease

Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

European particle-accelerator community publishes the first industry compendium

26.04.2018 | Physics and Astronomy

Multifunctional bacterial microswimmer able to deliver cargo and destroy itself

26.04.2018 | Life Sciences

Why we need erasable MRI scans

26.04.2018 | Medical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>