The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Mark Hübener - One of the best experts on this subject based on the ideXlab platform.
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Optical Imaging of Functional Architecture in Cat Primary Visual Cortex
The Cat Primary Visual Cortex, 2020Co-Authors: Mark Hübener, Tobias Bonhoeffer, PressAbstract:Publisher Summary This chapter describes some of the theoretical and methodological aspects of optical imaging. It reviews the basic findings on the structure of functional maps in the cat's primary Visual Cortex that have been obtained with optical imaging, and compares these results with observations made with other methods. One of the great strengths of optical imaging is that it allows the Visualization of different aspects of the functional architecture in the same region of the Visual Cortex. According to the concept of the modular organization of the Visual Cortex, the Visual Cortex is composed of many identical elementary processing units, with each module containing the neuronal circuitry for the analysis of a small patch of the Visual world with respect to all possible stimulus combinations. Although optical imaging has shown that each map in the Cortex exhibits a certain amount of regularity, it is hard to find evidence for modules in a strict sense, which would form the building blocks of the Visual Cortex It seems as if the Visual Cortex should rather be considered as containing mosaics of functional domains for the different properties that are arranged in a nonrandom manner. Optical imaging has therefore helped to further elucidate the fundamental question of how information about the Visual world is represented in the primary Visual Cortex.
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A Division of Light and Dark in the Visual Cortex.
Neuron, 2015Co-Authors: Pieter M. Goltstein, Mark HübenerAbstract:The fate of ON-OFF receptive field segregation in the Visual Cortex has long eluded scrutiny. In this issue of Neuron, Smith et al. (2015) now reveal the intricate relationship between luminance polarity and orientation selectivity in the upper layers of ferret Visual Cortex.
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sensorimotor mismatch signals in primary Visual Cortex of the behaving mouse
Neuron, 2012Co-Authors: Georg B. Keller, Tobias Bonhoeffer, Mark HübenerAbstract:Summary Studies in anesthetized animals have suggested that activity in early Visual Cortex is mainly driven by Visual input and is well described by a feedforward processing hierarchy. However, evidence from experiments on awake animals has shown that both eye movements and behavioral state can strongly modulate responses of neurons in Visual Cortex; the functional significance of this modulation, however, remains elusive. Using Visual-flow feedback manipulations during locomotion in a virtual reality environment, we found that responses in layer 2/3 of mouse primary Visual Cortex are strongly driven by locomotion and by mismatch between actual and expected Visual feedback. These data suggest that processing in Visual Cortex may be based on predictive coding strategies that use motor-related and Visual input to detect mismatches between predicted and actual Visual feedback.
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Critical-Period Plasticity in the Visual Cortex
Annual Review of Neuroscience, 2012Co-Authors: Christiaan N. Levelt, Mark HübenerAbstract:In many regions of the developing brain, neuronal circuits undergo defined phases of enhanced plasticity, termed critical periods. Work in the rodent Visual Cortex has led to important insights into the cellular and molecular mechanisms regulating the timing of the critical period. Although there is little doubt that the maturation of specific inhibitory circuits plays a key role in the opening of the critical period in the Visual Cortex, it is less clear what puts an end to it. In this review, we describe the established mechanisms and point out where more experimental work is needed. We also show that plasticity in the Visual Cortex is present well before, and long after, the peak of the critical period.
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Mouse Visual Cortex
Current Opinion in Neurobiology, 2003Co-Authors: Mark HübenerAbstract:Neurons in mouse Visual Cortex have diverse receptive field properties and they respond selectively to specific features of Visual stimuli. Owing to the lateral position of the eyes, only about a third of the Visual Cortex receives input from both eyes, but many cells in this region are binocular. Similar to higher mammals, closing one eye during a critical period shifts the responses of cells, such that they are better driven by the non-deprived eye. In this review I illustrate how the combination of transgenic mouse technology with single cell recording and modern imaging techniques might lead to a further understanding of the mechanisms that underlie the development, plasticity, and function of the mammalian Visual Cortex.
Lars Muckli - One of the best experts on this subject based on the ideXlab platform.
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Decoding sound and imagery content in early Visual Cortex.
Current Biology, 2014Co-Authors: Petra Vetter, Fraser W. Smith, Lars MuckliAbstract:Human early Visual Cortex was traditionally thought to process simple Visual features such as orientation, contrast, and spatial frequency via feedforward input from the lateral geniculate nucleus (e.g., [1]). However, the role of nonretinal influence on early Visual Cortex is so far insufficiently investigated despite much evidence that feedback connections greatly outnumber feedforward connections [2-5]. Here, we explored in five fMRI experiments how information originating from audition and imagery affects the brain activity patterns in early Visual Cortex in the absence of any feedforward Visual stimulation. We show that category-specific information from both complex natural sounds and imagery can be read out from early Visual Cortex activity in blindfolded participants. The coding of nonretinal information in the activity patterns of early Visual Cortex is common across actual auditory perception and imagery and may be mediated by higher-level multisensory areas. Furthermore, this coding is robust to mild manipulations of attention and working memory but affected by orthogonal, cognitively demanding visuospatial processing. Crucially, the information fed down to early Visual Cortex is category specific and generalizes to sound exemplars of the same category, providing evidence for abstract information feedback rather than precise pictorial feedback. Our results suggest that early Visual Cortex receives nonretinal input from other brain areas when it is generated by auditory perception and/or imagery, and this input carries common abstract information. Our findings are compatible with feedback of predictive information to the earliest Visual input level (e.g., [6]), in line with predictive coding models [7-10].
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Decoding sound and imagery content in early Visual Cortex
Current Biology, 2014Co-Authors: Petra Vetter, Fraser W. Smith, Lars MuckliAbstract:Human early Visual Cortex was traditionally thought to process simple Visual features such as orientation, contrast, and spatial frequency via feedforward input from the lateral geniculate nucleus (e.g., [1]). However, the role of nonretinal influence on early Visual Cortex is so far insufficiently investigated despite much evidence that feedback connections greatly outnumber feedforward connections [2-5]. Here, we explored in five fMRI experiments how information originating from audition and imagery affects the brain activity patterns in early Visual Cortex in the absence of any feedforward Visual stimulation. We show that category-specific information from both complex natural sounds and imagery can be read out from early Visual Cortex activity in blindfolded participants. The coding of nonretinal information in the activity patterns of early Visual Cortex is common across actual auditory perception and imagery and may be mediated by higher-level multisensory areas. Furthermore, this coding is robust to mild manipulations of attention and working memory but affected by orthogonal, cognitively demanding visuospatial processing. Crucially, the information fed down to early Visual Cortex is category specific and generalizes to sound exemplars of the same category, providing evidence for abstract information feedback rather than precise pictorial feedback. Our results suggest that early Visual Cortex receives nonretinal input from other brain areas when it is generated by auditory perception and/or imagery, and this input carries common abstract information. Our findings are compatible with feedback of predictive information to the earliest Visual input level (e.g., [6]), in line with predictive coding models [7-10]. © 2014 The Authors.
C. Campaigne - One of the best experts on this subject based on the ideXlab platform.
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Characterizing cortical dynamics using a large-scale model of turtle Visual Cortex
The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2004Co-Authors: P. Ulinski, C. CampaigneAbstract:Visual stimuli evoke waves of electrical activity that propagate across the Visual Cortex of freshwater turtles. The experimental methods used to demonstrate these waves measure the activity of populations of pyramidal cells. However, turtle Visual Cortex contains pyramidal cells and at least three populations of inhibitory interneurons. This study uses a large-scale model to characterize the time course of activity of each of the major populations of neurons in turtle Visual Cortex.
Georg B. Keller - One of the best experts on this subject based on the ideXlab platform.
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Experience-dependent spatial expectations in mouse Visual Cortex
Nature Neuroscience, 2016Co-Authors: Aris Fiser, David Mahringer, Hassana K Oyibo, Anders V. Petersen, Marcus Leinweber, Georg B. KellerAbstract:The authors find that activity in rodent Visual Cortex can depend on the animal's location in a virtual environment and can predict upcoming Visual stimuli. Omitting a stimulus that a mouse expects to see results in a strong mismatch signal, implying that Visual Cortex compares Visual signals to expectations in familiar environments.
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sensorimotor mismatch signals in primary Visual Cortex of the behaving mouse
Neuron, 2012Co-Authors: Georg B. Keller, Tobias Bonhoeffer, Mark HübenerAbstract:Summary Studies in anesthetized animals have suggested that activity in early Visual Cortex is mainly driven by Visual input and is well described by a feedforward processing hierarchy. However, evidence from experiments on awake animals has shown that both eye movements and behavioral state can strongly modulate responses of neurons in Visual Cortex; the functional significance of this modulation, however, remains elusive. Using Visual-flow feedback manipulations during locomotion in a virtual reality environment, we found that responses in layer 2/3 of mouse primary Visual Cortex are strongly driven by locomotion and by mismatch between actual and expected Visual feedback. These data suggest that processing in Visual Cortex may be based on predictive coding strategies that use motor-related and Visual input to detect mismatches between predicted and actual Visual feedback.
Tobias Bonhoeffer - One of the best experts on this subject based on the ideXlab platform.
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Optical Imaging of Functional Architecture in Cat Primary Visual Cortex
The Cat Primary Visual Cortex, 2020Co-Authors: Mark Hübener, Tobias Bonhoeffer, PressAbstract:Publisher Summary This chapter describes some of the theoretical and methodological aspects of optical imaging. It reviews the basic findings on the structure of functional maps in the cat's primary Visual Cortex that have been obtained with optical imaging, and compares these results with observations made with other methods. One of the great strengths of optical imaging is that it allows the Visualization of different aspects of the functional architecture in the same region of the Visual Cortex. According to the concept of the modular organization of the Visual Cortex, the Visual Cortex is composed of many identical elementary processing units, with each module containing the neuronal circuitry for the analysis of a small patch of the Visual world with respect to all possible stimulus combinations. Although optical imaging has shown that each map in the Cortex exhibits a certain amount of regularity, it is hard to find evidence for modules in a strict sense, which would form the building blocks of the Visual Cortex It seems as if the Visual Cortex should rather be considered as containing mosaics of functional domains for the different properties that are arranged in a nonrandom manner. Optical imaging has therefore helped to further elucidate the fundamental question of how information about the Visual world is represented in the primary Visual Cortex.
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sensorimotor mismatch signals in primary Visual Cortex of the behaving mouse
Neuron, 2012Co-Authors: Georg B. Keller, Tobias Bonhoeffer, Mark HübenerAbstract:Summary Studies in anesthetized animals have suggested that activity in early Visual Cortex is mainly driven by Visual input and is well described by a feedforward processing hierarchy. However, evidence from experiments on awake animals has shown that both eye movements and behavioral state can strongly modulate responses of neurons in Visual Cortex; the functional significance of this modulation, however, remains elusive. Using Visual-flow feedback manipulations during locomotion in a virtual reality environment, we found that responses in layer 2/3 of mouse primary Visual Cortex are strongly driven by locomotion and by mismatch between actual and expected Visual feedback. These data suggest that processing in Visual Cortex may be based on predictive coding strategies that use motor-related and Visual input to detect mismatches between predicted and actual Visual feedback.
