Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 73 for “"Primary visual cortex"”.
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Dynamic and Integrative Properties of the Primary Visual Cortex
… We have studied these processes in the primary visual cortex (V1), where neurons have been proposed to integrate visual inputs along a geometric pattern known as the association field (AF). We first used cortical reorganization as a model to investigate the role that a specific network …
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Inhibition stabilized network model in the primary visual cortex
… recent surround suppression experiments in the primary visual cortex with direct membrane conductance measurements (Ozeki et al., 2009). In our work, we used a linearized rate model of both excitatory and inhibitory populations with weight matrices dependent on the locations of the neurons. We …
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Passive experience-dependent plasticity in mouse primary visual cortex
… plasticity readily measured in primary visual cortex (V1) of mice. Chronic local field potential (LFP) recordings in layer 4 (L4) of V1 allow for the tracking of visually evoked potentials (VEPs) in response to phase-reversing sinusoidal grating stimuli. As a given visual …
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Computational models of contrast and orientation processing in primary visual cortex
Der primäre visuelle Kortex (V1) ist das erste kortikale Areal, das in der Verarbeitung visueller Informationen involviert ist. Die Zellen dieses Areals reagieren auf grundlegende Stimuluseigenschaften wie Kontrast oder Orientierung. Auch wenn es sich um den meistuntersuchten Teil des visuellen …
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Auditory Cortex Projections Target the Peripheral Field Representation of Primary Visual Cortex
… was to identify projections from auditory to visual cortex and their organization. Retrograde tracer wheat germ agglutinin conjugated to horseradish peroxidase was used to identify the sources of auditory cortical projections to primary visual cortex (areas 17&18) in adult cats. Two groups of …
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Non-invasive tuning of experience-dependent plasticity in the primary visual cortex
The cerebral cortex exhibits a remarkable capacity for experience-dependent plasticity, a feature that is predominantly confined to critical periods (CPs) during early postnatal development. In the mouse primary visual cortex (V1), ocular dominance plasticity (ODP) has served as a premier model for …
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Highly Selective Attentional Modulation of Task-Appropriate Neural Populations in Primary Visual Cortex
… the recently developed Input Gain Model of visual attention proposes that a simple neural mechanism, multiplicative gain, may be employed to explain much of the available data on visual attentional modulations. On this basis, we hypothesized that a better explanation for distinct forms of …
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Optogenetic Interrogation of Primary Visual Cortex and Its Impact On Neural Coding and Behavior
… monitor the resultant effects. Here we focus on primary visual cortex (V1), which has been shown to be crucial for visual perception, and utilize optogenetic tools to render the activity of genetically- defined neural populations sensitive to light. By simultaneously recording and modulating …
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Perceptual Learning, Long-Range Horizontal Connections And Top-Down Influences In Primary Visual Cortex
<p>The earliest cortical stage of visual processing, the primary visual cortex, has long been seen as a static preprocessor that finds local edges and their orientation like a linear filter bank, and passes this information on to downstream visual areas. This view has been challenged in recent …
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Information Encoding by Individual Neurons and Groups of Neurons in the Primary Visual Cortex
<p>How is information about visual stimuli encoded into the responses of neurons in the cerebral cortex? In this thesis, I describe the analysis of data recorded simultaneously from groups of up to eight nearby neurons in the primary visual cortices of anesthetized macaque monkeys. The goal is to …
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Ultrastructural correlates of axons and synapses belonging to different circuits in ferret primary visual cortex
… differences in distinctive layers of mammalian primary visual cortex through analysis of their ultrastructural characteristics. Characterizing brain circuitry using 3-dimensional reconstruction of electron microscopy images, and subsequent ultrastructural analysis of axonal populations provides …
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Understanding experience-dependent plasticity of cellular and network activity in the mouse primary visual cortex
… in daily life modulates corresponding primary sensory cortices and eventually alter our behavior in a befitting manner. One of the most impactful sensory modules is vision. Primary visual cortex (V1) in mammals is particularly malleable during a juvenile critical period, but this …
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The Role of Parvalbumin Interneurons in Mouse Primary Visual Cortex during Visual Discrimination and Perceptual Learning
… class of inhibitory interneurons in the rodent cortex and play important roles in balancing cortical circuit activity and learning (Xu et al., 2010). PV cells are suggested to mediate feedforward inhibition and control gain modulation (Markram et al., 2004; Tremblay et al., 2016). Although …
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Effects of Reticular Activation on Long-Term Depression in Primary Visual Cortex of the Long-Evans Rat
… levels of ongoing background activity in the primary visual cortex (V1) alter the effectiveness of LFS to induce LTD under in vivo conditions, using urethane anesthetized rats. LFS applied to the lateral geniculate nucleus resulted in LTD of field postsynaptic potentials (fPSPs) recorded in …
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Preliminary investigation of the temporal specificity of sequence learning in the primary visual cortex through predictive coding
The primary visual cortex (V1) has been classically viewed as an immutable feature detector, with robust responses to low-level characteristics of objects in the visual field. Recent studies have shown the capacity of this cortical area to perform more complex computations. Nominally, the …
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Developmental Cell Death and Androgens Affect Neuron Number in the Primary Visual Cortex of Male and Female Rats
… upon cell death in the developing rat posterior cortex. DHT implantation in females decreased the proportion of cells dying relative to control females (similar to control males), while estrogen implantation in females failed to alter cell death relative to control females. Thus, androgens are …
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A novel visual stimulation paradigm: exploiting individual primary visual cortex geometry to boost steady state visual evoked potentials (SSVEP)
<p>The steady-state visual evoked potential (SSVEP) is an electroencephalographic response to flickering stimuli generated in significant part by activity in primary visual cortex (V1). SSVEP signal-to-noise ratio is generally low for stimuli that are located in the visual periphery, at frequencies …
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Neurons in Cat Primary Visual Cortex cluster by degree of tuning but not by absolute spatial phase or temporal response phase
Neighboring neurons in cat primary visual cortex (V1) have similar preferred orientation, direction, and spatial frequency. How diverse is their degree of tuning for these properties? Are they also clustered in their tuning for the spatial phase of a flashed grating ("absolute spatial phase") or …
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