Researchers have designed a new computational model to study how nerve cells in the visual cortex process natural stimuli
At any given moment, the neuronal circuits in the brain receive and process sensory information that permits us to perceive and interact with the environment. Yet it remains unclear how the visual brain processes natural stimuli.
Together with an international team of researchers from the Centre Nationale de la Recherche Scientifique (CNRS) in Marseille, the CNRS in Gif-Sur-Yvette, and New York State University, neuroscientists Jens Kremkow and Ad Aertsen from the Bernstein Center Freiburg have developed a new computational model that simulates how neurons in the visual cortex process sensory stimuli.
This model may help neuroscientists to better understand how neuronal networks in the visual system process natural stimuli. The study has now been published in the journal Frontiers in Neural Circuits.
For decades, researchers have used simple artificial stimuli like moving bars to study the function of neuronal circuits in the visual system. In recent years, natural stimuli from the perception of daily life have taken on an increasingly important role in neuroscientific experiments.
“Studies revealed that the activity of neurons in the primary visual cortex was fundamentally different when they were exposed to artificial stimuli or to natural stimuli. While artificial stimuli evoked strong but temporally variable neuronal responses, neuronal responses to natural stimuli were weak but temporally precise. But we still did not understand why the neuronal networks change their activity dynamics in these cases,” says Kremkow.
With the help of their model, Kremkow and his colleagues have now provided a potential explanation: The distinctive neuronal responses may be the result of features commonly found in the pathways between the retina and the cortex. In particular, the precise interplay of excitatory and inhibitory synaptic inputs in the receptive fields of neurons in the visual cortex turned out to play a significant role.
The receptive fields of neurons in the visual cortex work similar to a camera sensor. They do not deliver sharp images of the environment but rather encode specific properties of the visual scene and contain excitatory and inhibitory areas. Artificial stimuli evoked temporally non-overlapping excitation and inhibition and strong neuronal responses.
When the neurons were exposed to natural stimuli, on the other hand, excitation and inhibition were temporally correlated, which explains the weak neuronal responses during natural viewing. In the opinion of Kremkow and Aertsen, this so-called push-and-pull mechanism could also be applied to the neuronal processing of natural stimuli in other sensory systems. Perhaps its malfunction could even be linked to perceptual impairments, in which case these results could lead to more questions for medical research.
Kremkow J, Perrinet LU, Monier C, Alonso J-M, Aertsen A, Fregnac Y, Masson GS (2016) Push-Pull Receptive Field Organization and Synaptic Depression: Mechanisms for Reliably Encoding Naturalistic Stimuli in V1. Frontiers in Neural Circuits 10:37; doi: 10.3389/fncir.2016.00037
Dr. Jens Kremkow
Bernstein Center Freiburg
University of Freiburg
Phone: +49 (0)30/450 - 539826
Bernstein Center Freiburg
Phone: +49 (0)761 / 203 - 9322
Rudolf-Werner Dreier | Albert-Ludwigs-Universität Freiburg im Breisgau
Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care
Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses