Navigation Links
Neurons subtract images and use the differences
Date:12/17/2013

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-Universitt Bochum (RUB) and the University of Osnabrck 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-Universitt. "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 Osnabrck 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.


'/>"/>

Contact: Dr. Dirk Jancke
dirk.jancke@rub.de
49-234-322-7845
Ruhr-University Bochum
Source:Eurekalert

Related biology news :

1. Uncovering first molecular missteps that drive neurons in pathway leading to Alzheimers disease
2. Biologists uncover details of how we squelch defective neurons
3. Penn study: Shutting off neurons helps bullied mice overcome symptoms of depression
4. Researchers discover how inhibitory neurons behave during critical periods of learning
5. Sympathetic neurons cross talk with pancreas cells during early development
6. Arg-Phe-amide-related peptides influence gonadotropin-releasing hormone neurons
7. Weapons testing data determines brain makes new neurons into adulthood
8. Down syndrome neurons grown from stem cells show signature problems
9. Serotonin mediates exercise-induced generation of new neurons
10. Vitamin P as a potential approach for the treatment of damaged motor neurons
11. Age-related dementia may begin with neurons inability to dispose of unwanted proteins
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/27/2020)... ... March 24, 2020 , ... PathSensors Inc, ... biosensor to detect the Novel SARS Coronavirus (SARS-CoV-2), the causal agent for the ... 2020 and validation data on the new SARS-CoV-2 product will be available June ...
(Date:3/20/2020)... OKLAHOMA CITY (PRWEB) , ... March 20, 2020 , ... ... of a vaccine for the COVID-19 virus. The scientific team is led by William ... virus-infected cells. He will be working with Pure MHC, part of a family of ...
(Date:3/19/2020)... (PRWEB) , ... March 17, 2020 , ... ... tools for characterizing microbiome populations down to the strain level, recently unveiled a ... Shoreline Wave amplicon kit contains the same innovative amplification capabilities as the Shoreline ...
Breaking Biology News(10 mins):
(Date:2/28/2020)... , ... February 26, 2020 , ... ... combines a high-speed camera with a dedicated controller, thus simplifying setup, streamlining ... second, the HS7 is the first of Fastec Imaging’s new HS Series cameras ...
(Date:2/21/2020)... , ... February 20, 2020 ... ... exquisite capability to perform complex, efficient and elegant chemistry. Humans have been ... to our own goals. , Through rapidly evolving technologies and strategies for ...
(Date:2/21/2020)... ... February 21, 2020 , ... Pharmaceutical manufacturers are under increasing ... adapt to new approaches like ‘Industry 4.0’ and continuous manufacturing, combat the growing ... and therapies. But with an industry with the world’s tightest regulations and complex ...
(Date:2/19/2020)... ... February 19, 2020 , ... Red Nucleus, ... sciences industry, today announced the opening of a new office in Tokyo, Japan. ... R&D. , Red Nucleus announced the new office in response to customer requests ...
Breaking Biology Technology: