PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Neurons subtract images and use the differences

Primary cortex generates efficiently compressed sensory information

2013-12-17
(Press-News.org) Contact information: Dr. Dirk Jancke
dirk.jancke@rub.de
49-234-322-7845
Ruhr-University Bochum
Neurons subtract images and use the differences Primary cortex generates efficiently compressed sensory information Ten million bits – that's the information volume transmitted every second with every quick eye movement from the eye to the cerebrum. Researchers from the Ruhr-Universität Bochum (RUB) and the University of Osnabrück describe the way those data are processed by the primary visual cortex, the entry point for the visual information into the brain, in the journal "Cerebral Cortex". Deploying novel optical imaging methods, they demonstrated that the brain does not always transmit the entire image information. Rather, it uses the differences between current and previously viewed images.

Efficient reduction of data volumes

Researchers have hitherto assumed that information supplied by the sense of sight was transmitted almost in its entirety from its entry point to higher brain areas, across which visual sensation is generated. "It was therefore a surprise to discover that the data volumes are considerably reduced as early as in the primary visual cortex, the bottleneck leading to the cerebrum," says PD Dr Dirk Jancke from the Institute for Neural Computation at the Ruhr-Universität. "We intuitively assume that our visual system generates a continuous stream of images, just like a video camera. However, we have now demonstrated that the visual cortex suppresses redundant information and saves energy by frequently forwarding image differences."

Plus or minus: the brain's two coding strategies

The researchers recorded the neurons' responses to natural image sequences, for example vegetation landscapes or buildings. They created two versions of the images: a complete one and one in which they had systematically removed certain elements, specifically vertical or horizontal contours. If the time elapsing between the individual images was short, i.e. 30 milliseconds, the neurons represented complete image information. That changed when the time elapsing in the sequences was longer than 100 milliseconds. Now, the neurons represented only those elements that were new or missing, namely image differences. "When we analyse a scene, the eyes perform very fast miniature movements in order to register the fine details," explains Nora Nortmann, postgraduate student at the Institute of Cognitive Science at the University of Osnabrück and the RUB work group Optical Imaging. The information regarding those details are forwarded completely and immediately by the primary visual cortex. "If, on the other hand, the time elapsing between the gaze changes is longer, the cortex codes only those aspects in the images that have changed," continues Nora Nortmann. Thus, certain image sections stand out and interesting spots are easier to detect, as the researchers speculate.

"Our brain is permanently looking into the future"

This study illustrates how activities of visual neurons are influenced by past events. "The neurons build up a short-term memory that incorporates constant input," explains Dirk Jancke. However, if something changes abruptly in the perceived image, the brain generates a kind of error message on the basis of the past images. Those signals do not reflect the current input, but the way the current input deviates from the expectations. Researchers have hitherto postulated that this so-called predictive coding only takes place in higher brain areas. "We demonstrated that the principle applies for earlier phases of cortical processing, too," concludes Jancke. "Our brain is permanently looking into the future and comparing current input with the expectations that arose based on past situations."

Observing brain activities in millisecond range

In order to monitor the dynamics of neuronal activities in the brain in the millisecond range, the scientists used voltage-dependent dyes. Those substances fluoresce when neurons receive electrical impulses and become active. Thanks to a high-resolution camera system and the subsequent computer-aided analysis, the neuronal activity can be measured across a surface of several square millimetres. The result is a temporally and spatially precise film of transmission processes within neuronal networks.

### Bibliographic record

N. Nortmann, S. Rekauzke, S. Onat, P. König, D. Jancke (2013): Primary visual cortex represents the difference between past and present, Cerebral Cortex, DOI: 10.1093/cercor/bht318

Further information

PD Dr Dirk Jancke, Optical Imaging Group, Institute for Neural Computation at the Ruhr-Universität, 44780 Bochum, Germany, phone +49/234/32-27845, email: dirk.jancke@rub.de

Editor: Dr Julia Weiler


ELSE PRESS RELEASES FROM THIS DATE:

Sharpening the focus in quantum photolithography

2013-12-17
Sharpening the focus in quantum photolithography A new protocol makes it possible to improve the accuracy of photolithography by addressing its physical limitations Photolithography uses light beams to design thin geometric patterns on the substrates of semiconductors ...

Use biologic agents to induce remission in patients with moderately severe Crohn's disease

2013-12-17
Use biologic agents to induce remission in patients with moderately severe Crohn's disease New American Gastroenterological Association guidelines provide guidance on most effective treatment pathway Bethesda, MD (Dec. 16, 2013) —The anti-TNF-α ...

Smoking changes our genes

2013-12-17
Smoking changes our genes The fact that smoking means a considerable health risk is nowadays commonly accepted. New research findings from Uppsala University and Uppsala Clinical Research Center show that smoking alters several genes that can be associated ...

AAOS approves AUC for non-arthroplasty treatment of osteoarthritis of the knee

2013-12-17
AAOS approves AUC for non-arthroplasty treatment of osteoarthritis of the knee New AUC offers clinical expertise across medical specialties to help optimize patient care ROSEMONT, Ill. – The American Academy of Orthopaedic Surgeons (AAOS) Board of Directors ...

Uranium (IV) found to be mobile in a natural wetland

2013-12-17
Uranium (IV) found to be mobile in a natural wetland EPFL researchers studying a natural wetland near a decommissioned uranium mine in Limousin, France, have shown that under certain circumstances the uranium present in the wetland could be more mobile ...

Carsey Institute: Students with a disability more likely to be restrained, secluded in school

2013-12-17
Carsey Institute: Students with a disability more likely to be restrained, secluded in school DURHAM, N.H. – The restraint and seclusion of students in U.S. public schools in response to student behavior problems are used much more frequently on students with ...

Duration of diabetes and advancing age independently predict diabetes complications, risk of death

2013-12-17
Duration of diabetes and advancing age independently predict diabetes complications, risk of death The duration of diabetes and advancing age independently predict diabetes severity and risk of death in older adults with type 2 diabetes according to a study by the ...

Hippocampal volume loss in depression reflects glial loss

2013-12-17
Hippocampal volume loss in depression reflects glial loss Reports new study in Biological Psychiatry Philadelphia, PA, December 17, 2013 – Depression has been associated with reduced volume of the hippocampus in magnetic resonance imaging studies in humans. A new study ...

Health R&D spending moves slowly upward, driven by industry, philanthropy and voluntary associations

2013-12-17
Health R&D spending moves slowly upward, driven by industry, philanthropy and voluntary associations Federal R&D funding remains 'woefully inadequate' to address health threats and global competitiveness ALEXANDRIA, Va.—December 17, 2013—After declining in ...

The economically valuable sweet-gum trees: Taxonomy and 9 new combinations

2013-12-17
The economically valuable sweet-gum trees: Taxonomy and 9 new combinations The sweet-gum family Altingiaceae is a small group of wind-pollinated trees that produce hard, woody fruits that contain numerous seeds. This widespread tree family has been puzzling botanists ...

LAST 30 PRESS RELEASES:

Printed skin to replace animal testing

Precision medicine could be possible in the fight against antibiotic resistance

Researchers at the Lewis Katz School of Medicine at Temple University identify new targeted approach to protect neurons against degeneration

Western diet causes inflammation, traditional African food protects

Electrochemical method supports nitrogen circular economy

How researchers are shining a light on kidney disease

Some gut bacteria could make certain drugs less effective

PEPITEM sequence shows effects in psoriasis, comparable to steroid cream

Older teens who start vaping post-high school risk rapid progress to frequent use

Corpse flowers are threatened by spotty recordkeeping

Riding the AI wave toward rapid, precise ocean simulations

Are lifetimes of big appliances really shrinking?

Pink skies

Monkeys are world’s best yodellers - new research

Key differences between visual- and memory-led Alzheimer’s discovered

% weight loss targets in obesity management – is this the wrong objective?

An app can change how you see yourself at work

NYC speed cameras take six months to change driver behavior, effects vary by neighborhood, new study reveals

New research shows that propaganda is on the rise in China

Even the richest Americans face shorter lifespans than their European counterparts, study finds

Novel genes linked to rare childhood diarrhea

New computer model reveals how Bronze Age Scandinavians could have crossed the sea

Novel point-of-care technology delivers accurate HIV results in minutes

Researchers reveal key brain differences to explain why Ritalin helps improve focus in some more than others

Study finds nearly five-fold increase in hospitalizations for common cause of stroke

Study reveals how alcohol abuse damages cognition

Medicinal cannabis is linked to long-term benefits in health-related quality of life

Microplastics detected in cat placentas and fetuses during early pregnancy

Ancient amphibians as big as alligators died in mass mortality event in Triassic Wyoming

Scientists uncover the first clear evidence of air sacs in the fossilized bones of alvarezsaurian dinosaurs: the "hollow bones" which help modern day birds to fly

[Press-News.org] Neurons subtract images and use the differences
Primary cortex generates efficiently compressed sensory information