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Littérature scientifique sur le sujet « Primary Visual Cortex (PVC) »

Auteur : Grafiati

Publié le 2 novembre 2024

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Articles de revues sur le sujet "Primary Visual Cortex (PVC)"

Dai, Peishan, Jinlong Zhang, Jing Wu, Zailiang Chen, Beiji Zou, Ying Wu, Xin Wei et Manyi Xiao. « Altered Spontaneous Brain Activity of Children with Unilateral Amblyopia : A Resting State fMRI Study ». Neural Plasticity 2019 (25 juillet 2019) : 1–10. http://dx.doi.org/10.1155/2019/3681430.

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Objective. This study is aimed at investigating differences in local brain activity and functional connectivity (FC) between children with unilateral amblyopia and healthy controls (HCs) by using resting state functional magnetic resonance imaging (rs-fMRI). Methods. Local activity and FC analysis methods were used to explore the altered spontaneous brain activity of children with unilateral amblyopia. Local brain function analysis methods included the amplitude of low-frequency fluctuation (ALFF). FC analysis methods consisted of the FC between the primary visual cortex (PVC-FC) and other brain regions and the FC network between regions of interest (ROIs-FC) selected by independent component analysis. Results. The ALFF in the bilateral frontal, temporal, and occipital lobes in the amblyopia group was lower than that in the HCs. The weakened PVC-FC was mainly concentrated in the frontal lobe and the angular gyrus. The ROIs-FC between the default mode network, salience network, and primary visual cortex network (PVCN) were significantly reduced, whereas the ROIs-FC between the PVCN and the high-level visual cortex network were significantly increased in amblyopia. Conclusions. Unilateral amblyopia may reduce local brain activity and FC in the dorsal and ventral visual pathways and affect the top-down attentional control. Amblyopia may also alter FC between brain functional networks. These findings may help understand the pathological mechanisms of children with amblyopia.

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Padnick, Lissa B., Robert A. Linsenmeier et Thomas K. Goldstick. « Perfluorocarbon emulsion improves oxygenation of the cat primary visual cortex ». Journal of Applied Physiology 86, n^o 5 (1 mai 1999) : 1497–504. http://dx.doi.org/10.1152/jappl.1999.86.5.1497.

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Tissue[Formula: see text] was measured in the primary visual cortex of anesthetized, artificially ventilated, normovolemic cats to evaluate the effect of small doses [1 g perfluorocarbon (PFC)/kg] of a PFC emulsion (1 g PFC/1.1 ml emulsion; Alliance Pharmaceutical, San Diego, CA) on brain oxygenation. The change in tissue [Formula: see text]([Formula: see text]), resulting from briefly changing the respiratory gas from room air to 100% oxygen, was measured before and after intravenous infusion of the emulsion. Before emulsion, [Formula: see text] was 51.1 ± 45.6 Torr ( n = 8 cats). Increases in [Formula: see text] of 34.0 ± 26.1 (SD) % ( n = 8) and 16.3 ± 8.4% ( n = 6) were observed after the first and second emulsion infusions, respectively. The further increase in [Formula: see text] after the third dose (7.9 ± 10.5%; n = 7) was not statistically significant. The observed increases in tissue oxygenation as a result of the PFC infusions appear to be the result of enhanced oxygen transport to the tissue.

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Reed, Catherine L. « Divisions within the posterior parietal cortex help touch meet vision ». Behavioral and Brain Sciences 30, n^o 2 (avril 2007) : 218. http://dx.doi.org/10.1017/s0140525x07001574.

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AbstractThe parietal cortex is divided into two major functional regions: the anterior parietal cortex that includes primary somatosensory cortex, and the posterior parietal cortex (PPC) that includes the rest of the parietal lobe. The PPC contains multiple representations of space. In Dijkerman & de Haan's (D&dH's) model, higher spatial representations are separate from PPC functions. This model should be developed further so that the functions of the somatosensory system are integrated with specific functions within the PPC and higher spatial representations. Through this further specification of the model, one can make better predictions regarding functional interactions between somatosensory and visual systems.

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Karabanov, Anke, Seung-Hyun Jin, Atte Joutsen, Brach Poston, Joshua Aizen, Aviva Ellenstein et Mark Hallett. « Timing-dependent modulation of the posterior parietal cortex–primary motor cortex pathway by sensorimotor training ». Journal of Neurophysiology 107, n^o 11 (1 juin 2012) : 3190–99. http://dx.doi.org/10.1152/jn.01049.2011.

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Interplay between posterior parietal cortex (PPC) and ipsilateral primary motor cortex (M1) is crucial during execution of movements. The purpose of the study was to determine whether functional PPC–M1 connectivity in humans can be modulated by sensorimotor training. Seventeen participants performed a sensorimotor training task that involved tapping the index finger in synchrony to a rhythmic sequence. To explore differences in training modality, one group ( n = 8) learned by visual and the other ( n = 9) by auditory stimuli. Transcranial magnetic stimulation (TMS) was used to assess PPC–M1 connectivity before and after training, whereas electroencephalography (EEG) was used to assess PPC–M1 connectivity during training. Facilitation from PPC to M1 was quantified using paired-pulse TMS at conditioning-test intervals of 2, 4, 6, and 8 ms by measuring motor-evoked potentials (MEPs). TMS was applied at baseline and at four time points (0, 30, 60, and 180 min) after training. For EEG, task-related power and coherence were calculated for early and late training phases. The conditioned MEP was facilitated at a 2-ms conditioning-test interval before training. However, facilitation was abolished immediately following training, but returned to baseline at subsequent time points. Regional EEG activity and interregional connectivity between PPC and M1 showed an initial increase during early training followed by a significant decrease in the late phases. The findings indicate that parietal–motor interactions are activated during early sensorimotor training when sensory information has to be integrated into a coherent movement plan. Once the sequence is encoded and movements become automatized, PPC–M1 connectivity returns to baseline.

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Yan, Xiaodan. « Dissociated Emergent-Response System and Fine-Processing System in Human Neural Network and a Heuristic Neural Architecture for Autonomous Humanoid Robots ». Computational Intelligence and Neuroscience 2010 (2010) : 1–8. http://dx.doi.org/10.1155/2010/314932.

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The current study investigated the functional connectivity of the primary sensory system with resting state fMRI and applied such knowledge into the design of the neural architecture of autonomous humanoid robots. Correlation and Granger causality analyses were utilized to reveal the functional connectivity patterns. Dissociation was within the primary sensory system, in that the olfactory cortex and the somatosensory cortex were strongly connected to the amygdala whereas the visual cortex and the auditory cortex were strongly connected with the frontal cortex. The posterior cingulate cortex (PCC) and the anterior cingulate cortex (ACC) were found to maintain constant communication with the primary sensory system, the frontal cortex, and the amygdala. Such neural architecture inspired the design of dissociated emergent-response system and fine-processing system in autonomous humanoid robots, with separate processing units and another consolidation center to coordinate the two systems. Such design can help autonomous robots to detect and respond quickly to danger, so as to maintain their sustainability and independence.

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Liu, Qin, Antonio Ulloa et Barry Horwitz. « Using a Large-scale Neural Model of Cortical Object Processing to Investigate the Neural Substrate for Managing Multiple Items in Short-term Memory ». Journal of Cognitive Neuroscience 29, n^o 11 (novembre 2017) : 1860–76. http://dx.doi.org/10.1162/jocn_a_01163.

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Many cognitive and computational models have been proposed to help understand working memory. In this article, we present a simulation study of cortical processing of visual objects during several working memory tasks using an extended version of a previously constructed large-scale neural model [Tagamets, M. A., & Horwitz, B. Integrating electrophysiological and anatomical experimental data to create a large-scale model that simulates a delayed match-to-sample human brain imaging study. Cerebral Cortex, 8, 310–320, 1998]. The original model consisted of arrays of Wilson–Cowan type of neuronal populations representing primary and secondary visual cortices, inferotemporal (IT) cortex, and pFC. We added a module representing entorhinal cortex, which functions as a gating module. We successfully implemented multiple working memory tasks using the same model and produced neuronal patterns in visual cortex, IT cortex, and pFC that match experimental findings. These working memory tasks can include distractor stimuli or can require that multiple items be retained in mind during a delay period (Sternberg's task). Besides electrophysiology data and behavioral data, we also generated fMRI BOLD time series from our simulation. Our results support the involvement of IT cortex in working memory maintenance and suggest the cortical architecture underlying the neural mechanisms mediating particular working memory tasks. Furthermore, we noticed that, during simulations of memorizing a list of objects, the first and last items in the sequence were recalled best, which may implicate the neural mechanism behind this important psychological effect (i.e., the primacy and recency effect).

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Everling, Stefan, et Kevin Johnston. « Control of the superior colliculus by the lateral prefrontal cortex ». Philosophical Transactions of the Royal Society B : Biological Sciences 368, n^o 1628 (19 octobre 2013) : 20130068. http://dx.doi.org/10.1098/rstb.2013.0068.

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Several decades of patient, functional imaging and neurophysiological studies have supported a model in which the lateral prefrontal cortex (PFC) acts to suppress unwanted saccades by inhibiting activity in the oculomotor system. However, recent results from combined PFC deactivation and neural recordings of the superior colliculus in monkeys demonstrate that the primary influence of the PFC on the oculomotor system is excitatory, and stands in direct contradiction to the inhibitory model of PFC function. Although erroneous saccades towards a visual stimulus are commonly labelled reflexive in patients with PFC damage or dysfunction, the latencies of most of these saccades are outside of the range of express saccades, which are triggered directly by the visual stimulus. Deactivation and pharmacological manipulation studies in monkeys suggest that response errors following PFC damage or dysfunction are not the result of a failure in response suppression but can best be understood in the context of a failure to maintain and implement the proper task set.

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Oh, Jihoon, Jae Hyung Kwon, Po Song Yang et Jaeseung Jeong. « Auditory Imagery Modulates Frequency-specific Areas in the Human Auditory Cortex ». Journal of Cognitive Neuroscience 25, n^o 2 (février 2013) : 175–87. http://dx.doi.org/10.1162/jocn_a_00280.

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Neural responses in early sensory areas are influenced by top–down processing. In the visual system, early visual areas have been shown to actively participate in top–down processing based on their topographical properties. Although it has been suggested that the auditory cortex is involved in top–down control, functional evidence of topographic modulation is still lacking. Here, we show that mental auditory imagery for familiar melodies induces significant activation in the frequency-responsive areas of the primary auditory cortex (PAC). This activation is related to the characteristics of the imagery: when subjects were asked to imagine high-frequency melodies, we observed increased activation in the high- versus low-frequency response area; when the subjects were asked to imagine low-frequency melodies, the opposite was observed. Furthermore, we found that A1 is more closely related to the observed frequency-related modulation than R in tonotopic subfields of the PAC. Our findings suggest that top–down processing in the auditory cortex relies on a mechanism similar to that used in the perception of external auditory stimuli, which is comparable to early visual systems.

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Sellers, Kristin K., Davis V. Bennett, Axel Hutt, James H. Williams et Flavio Fröhlich. « Awake vs. anesthetized : layer-specific sensory processing in visual cortex and functional connectivity between cortical areas ». Journal of Neurophysiology 113, n^o 10 (juin 2015) : 3798–815. http://dx.doi.org/10.1152/jn.00923.2014.

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During general anesthesia, global brain activity and behavioral state are profoundly altered. Yet it remains mostly unknown how anesthetics alter sensory processing across cortical layers and modulate functional cortico-cortical connectivity. To address this gap in knowledge of the micro- and mesoscale effects of anesthetics on sensory processing in the cortical microcircuit, we recorded multiunit activity and local field potential in awake and anesthetized ferrets ( Mustela putoris furo) during sensory stimulation. To understand how anesthetics alter sensory processing in a primary sensory area and the representation of sensory input in higher-order association areas, we studied the local sensory responses and long-range functional connectivity of primary visual cortex (V1) and prefrontal cortex (PFC). Isoflurane combined with xylazine provided general anesthesia for all anesthetized recordings. We found that anesthetics altered the duration of sensory-evoked responses, disrupted the response dynamics across cortical layers, suppressed both multimodal interactions in V1 and sensory responses in PFC, and reduced functional cortico-cortical connectivity between V1 and PFC. Together, the present findings demonstrate altered sensory responses and impaired functional network connectivity during anesthesia at the level of multiunit activity and local field potential across cortical layers.

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Hedrick, Tristan, et Jack Waters. « Acetylcholine excites neocortical pyramidal neurons via nicotinic receptors ». Journal of Neurophysiology 113, n^o 7 (avril 2015) : 2195–209. http://dx.doi.org/10.1152/jn.00716.2014.

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The neuromodulator acetylcholine (ACh) shapes neocortical function during sensory perception, motor control, arousal, attention, learning, and memory. Here we investigate the mechanisms by which ACh affects neocortical pyramidal neurons in adult mice. Stimulation of cholinergic axons activated muscarinic and nicotinic ACh receptors on pyramidal neurons in all cortical layers and in multiple cortical areas. Nicotinic receptor activation evoked short-latency, depolarizing postsynaptic potentials (PSPs) in many pyramidal neurons. Nicotinic receptor-mediated PSPs promoted spiking of pyramidal neurons. The duration of the increase in spiking was membrane potential dependent, with nicotinic receptor activation triggering persistent spiking lasting many seconds in neurons close to threshold. Persistent spiking was blocked by intracellular BAPTA, indicating that nicotinic ACh receptor activation evoked persistent spiking via a long-lasting calcium-activated depolarizing current. We compared nicotinic PSPs in primary motor cortex (M1), prefrontal cortex (PFC), and visual cortex. The laminar pattern of nicotinic excitation was not uniform but was broadly similar across areas, with stronger modulation in deep than superficial layers. Superimposed on this broad pattern were local differences, with nicotinic PSPs being particularly large and common in layer 5 of M1 but not layer 5 of PFC or primary visual cortex (V1). Hence, in addition to modulating the excitability of pyramidal neurons in all layers via muscarinic receptors, synaptically released ACh preferentially increases the activity of deep-layer neocortical pyramidal neurons via nicotinic receptors, thereby adding laminar selectivity to the widespread enhancement of excitability mediated by muscarinic ACh receptors.

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Thèses sur le sujet "Primary Visual Cortex (PVC)"

Remy, Irving. « Les fonctions visuelles rétiniennes et corticales dans les troubles du spectre de la schizophrénie et les situations à risque de psychose ». Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAJ030.

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Les troubles psychotiques sont caractérisés par d’importantes conséquences fonctionnelles avec des preuves émergentes concernant l’altération des fonctions visuelles de bas niveau. Le lien anatomique et fonctionnel entre la rétine et le cortex visuel a notamment permis d’émettre des hypothèses quant à l’association entre les altérations des deux étages visuels. Nous avons investigué les mesures électrophysiologiques visuelles rétiniennes et corticales dans les troubles du spectre de la schizophrénie et dans les situations à risque de psychose dont l’usage régulier de cannabis et les phases précoces de psychose font partie intégrante. Les résultats ont mentionné des altérations portant sur la plupart des cellules rétiniennes et des déficits au regard du cortex visuel primaire, avec un lien potentiel entre les deux types de mesures dans la schizophrénie. L’intérêt des biomarqueurs électrophysiologiques réside également dans le lien décrit avec les symptômes de la psychose, ce qui incite ainsi à les utiliser davantage en pratique clinique à des fins d’améliorations diagnostiques
Psychotic disorders are characterized by severe functional consequences, with emerging evidence of impairment in low-level visual functions. Most notably, the anatomical and functional link between the retina and the visual cortex led to hypotheses concerning the association between alterations in both visual stages. We investigated retinal and cortical visual electrophysiological measurements in schizophrenia spectrum disorders and situations at risk of psychosis, of which regular cannabis use and early phases of psychosis are an integral part. The results highlighted alterations in most retinal cells and deficits in the primary visual cortex, with a potential link between both measures in schizophrenia. The relevance of electrophysiological biomarkers also lies in the link described with psychotic symptoms, motivating them to be used more widely in clinical practice to improve diagnosis

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Fotheringhame, David K. « Temporal coding in primary visual cortex ». Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339357.

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Nauhaus, Ian Michael. « Functional connectivity in primary visual cortex ». Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1692099811&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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Thulin, Nilsson Linnea. « The Role of Primary Visual Cortex in Visual Awareness ». Thesis, Högskolan i Skövde, Institutionen för biovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-11623.

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Despite its great complexity, a great deal is known about the organization and information-processing properties of the visual system. However, the neural correlates of visual awareness are not yet understood. By studying patients with blindsight, the primary visual cortex (V1) has attracted a lot of attention recently. Although this brain area appears to be important for visual awareness, its exact role is still a matter of debate. Interactive models propose a direct role for V1 in generating visual awareness through recurrent processing. Hierarchal models instead propose that awareness is generated in later visual areas and that the role of V1 is limited to transmitting the necessary information to these areas. Interactive and hierarchical models make different predictions and the aim of this thesis is to review the evidence from lesions, perceptual suppression, and transcranial magnetic stimulation (TMS), along with data from internally generated visual awareness in dreams, hallucinations and imagery, this in order to see whether current evidence favor one type of model over the other. A review of the evidence suggests that feedback projections to V1 appear to be important in most cases for visual awareness to arise but it can arise even when V1 is absent.

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Krug, Kristine. « Ordering geniculate input into primary visual cortex ». Thesis, University of Oxford, 1997. https://ora.ox.ac.uk/objects/uuid:b342ffae-4a31-4171-94a6-83cb516e83fe.

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Precise point-to-point connectivity is the basis of ordered maps of the visual field in the brain. One point in the visual field is represented at one locus in the dLGN and one locus in primary visual cortex. A fundamental problem in the development of most sensory systems is the creation of the topographic projections which underlie these maps. Mechanisms ranging from ordered ingrowth of fibres, through chemical guidance of axons to sculpting of the map from an early exuberant input have been proposed. However, we know little about how ordered maps are created beyond the first relay. What we do know is that a topological mismatch requires the exchange of neighbours in the geniculo-cortical projection and that manipulating the input to the primary relay can affect the geniculo-cortical topography. Taking advantage of the immaturity of the newborn hamsterâs visual system, I studied the generation of an ordered map in primary visual cortex during the time of target innervation in normal and manipulated animals. I also investigated the patterning of neuronal activity prior to natural eye-opening. Paired injections of retrograde fluorescent tracers into visual cortex reveal that geniculate fibres are highly disordered at the time of invasion of the cortical plate. Topography in the geniculo-cortical projection emerges out of an unordered projection to area 17 in the first postnatal week. Furthermore, I show that manipulating the peripheral input can alter the topographic map which arises out of the early scatter. Removal of one eye at birth appears to slow the process of geniculo-cortical map formation ipsilateral to the remaining eye and at the end of the second postnatal week, a double projection between thalamus and cortex has formed. If retinal activity is blocked during this time, this double projection does not emerge. The results implicate retinal activity as the signal that induces the development of a different topographic order in the geniculo-cortical projection. It is generally believed that visual experience can influence development only after eye-opening. However, the final part of my thesis shows that neurons in the developing visual cortex of the ferret can not only be visually driven at least 10 days before natural eye-opening, but are also selective for differently oriented gratings presented through the closed eye-lid. Thus, visually-driven neuronal activity could influence development much earlier than previously assumed in many developmental studies.

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Hesam, Shariati Nastaran. « A functional model for primary visual cortex ». Thesis, The University of Sydney, 2012. http://hdl.handle.net/2123/8753.

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Many neurons in mammalian primary visual cortex have properties such as sharp tuning for contour orientation, strong selectivity for motion direction, and insensitivity to stimulus polarity, that are not shared with their sub-cortical counterparts. Successful models have been developed for a number of these properties but in one case, direction selectivity, there is no consensus about underlying mechanisms. This thesis describes a model that accounts for many of the empirical observations concerning direction selectivity. The model comprises a single column of cat primary visual cortex and a series of processing stages. Each neuron in the first cortical stage receives input from a small number of on-centre and off-centre relay cells in the lateral geniculate nucleus. Consistent with recent physiological evidence, the off-centre inputs to cortex precede the on-centre inputs by a small interval (~4 ms), and it is this difference that confers direction selectivity on model neurons. I show that the resulting model successfully matches the following empirical data: the proportion of cells that are direction selective; tilted spatiotemporal receptive fields; phase advance in the response to a stationary contrast-reversing grating stepped across the receptive field. The model also accounts for several other fundamental properties. Receptive fields have elongated subregions, orientation selectivity is strong, and the distribution of orientation tuning bandwidth across neurons is similar to that seen in the laboratory. Finally, neurons in the first stage have properties corresponding to simple cells, and more complex-like cells emerge in later stages. The results therefore show that a simple feed-forward model can account for a number of the fundamental properties of primary visual cortex.

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Rudiger, Philipp John Frederic. « Development and encoding of visual statistics in the primary visual cortex ». Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/25469.

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How do circuits in the mammalian cerebral cortex encode properties of the sensory environment in a way that can drive adaptive behavior? This question is fundamental to neuroscience, but it has been very difficult to approach directly. Various computational and theoretical models can explain a wide range of phenomena observed in the primary visual cortex (V1), including the anatomical organization of its circuits, the development of functional properties like orientation tuning, and behavioral effects like surround modulation. However, so far no model has been able to bridge these levels of description to explain how the machinery that develops directly affects behavior. Bridging these levels is important, because phenomena at any one specific level can have many possible explanations, but there are far fewer possibilities to consider once all of the available evidence is taken into account. In this thesis we integrate the information gleaned about cortical development, circuit and cell-type specific interactions, and anatomical, behavioral and electrophysiological measurements, to develop a computational model of V1 that is constrained enough to make predictions across multiple levels of description. Through a series of models incorporating increasing levels of biophysical detail and becoming increasingly better constrained, we are able to make detailed predictions for the types of mechanistic interactions required for robust development of cortical maps that have a realistic anatomical organization, and thereby gain insight into the computations performed by the primary visual cortex. The initial models focus on how existing anatomical and electrophysiological knowledge can be integrated into previously abstract models to give a well-grounded and highly constrained account of the emergence of pattern-specific tuning in the primary visual cortex. More detailed models then address the interactions between specific excitatory and inhibitory cell classes in V1, and what role each cell type may play during development and function. Finally, we demonstrate how these cell classes come together to form a circuit that gives rise not only to robust development but also the development of realistic lateral connectivity patterns. Crucially, these patterns reflect the statistics of the visual environment to which the model was exposed during development. This property allows us to explore how the model is able to capture higher-order information about the environment and use that information to optimize neural coding and aid the processing of complex visual tasks. Using this model we can make a number of very specific predictions about the mechanistic workings of the brain. Specifically, the model predicts a crucial role of parvalbumin-expressing interneurons in robust development and divisive normalization, while it implicates somatostatin immunoreactive neurons in mediating longer range and feature-selective suppression. The model also makes predictions about the role of these cell classes in efficient neural coding and under what conditions the model fails to organize. In particular, we show that a tight coupling of activity between the principal excitatory population and the parvalbumin population is central to robust and stable responses and organization, which may have implications for a variety of diseases where parvalbumin interneuron function is impaired, such as schizophrenia and autism. Further the model explains the switch from facilitatory to suppressive surround modulation effects as a simple by-product of the facilitating response function of long-range excitatory connections targeting a specialized class of inhibitory interneurons. Finally, the model allows us to make predictions about the statistics that are encoded in the extensive network of long-range intra-areal connectivity in V1, suggesting that even V1 can capture high-level statistical dependencies in the visual environment. The final model represents a comprehensive and well constrained model of the primary visual cortex, which for the first time can relate the physiological properties of individual cell classes to their role in development, learning and function. While the model is specifically tuned for V1, all mechanisms introduced are completely general, and can be used as a general cortical model, useful for studying phenomena across the visual cortex and even the cortex as a whole. This work is also highly relevant for clinical neuroscience, as the cell types studied here have been implicated in neurological disorders as wide ranging as autism, schizophrenia and Parkinson’s disease.

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De, Pasquale Roberto. « Visual discrimination learning and LTP-like changes in primary visual cortex ». Doctoral thesis, Scuola Normale Superiore, 2009. http://hdl.handle.net/11384/85939.

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Spacek, Martin A. « Characterizing patches of primary visual cortex with minimal bias ». Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/53975.

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The brain is highly complex, and studying it requires simplifying experiments, analyses, and theories. New techniques can capture more of the brain's complexity while reducing biases in our understanding of how it works. This thesis describes experiments in primary visual cortex of anesthetized cat, using high-density silicon multisite electrodes to simultaneously record from as many neurons as possible across all cortical layers, thereby characterizing local cortical populations with minimal bias. Recordings were maintained for many hours at a time, and included both spontaneous and stimulus-evoked periods, with a wide variety of naturalistic and artificial visual stimuli. A new "divide-and-conquer" spike sorting method translated correlated multisite voltages into action potentials of spatially localized, isolated neurons. This method tracked neurons over periods of many hours despite drift, and distinguished neurons with firing rates < 0.05 Hz. Neuron physiology was reasonably normal and mostly agreed with accepted principles of visual cortex, but there were exceptions. Surprisingly, firing rates across the population followed a lognormal distribution, and 82% of neurons had mean firing rates < 1 Hz. Also surprisingly, orientation tuning strength across the population was inversely correlated with log firing rate. Finally, there was evidence for neural shift work: over long durations, as some neurons became silent, others became active. To break down analyses by cell type, neurons were classified by their temporal spike shape and receptive field. Responses to repeated natural scene movie clips consisted of unique patterns of remarkably sparse, temporally precise (20 ms wide), reliable events. Mean pairwise correlations between neurons, as measured between trial-averaged responses to natural scene movies, were weakly positive. Correlations between simple and complex cells were lower — and between complex cells were higher — than expected, challenging the hierarchical model of complex cells. Cortical state was classified according to the local field potential, revealing greater natural scene movie response precision, sparseness, and reliability during the synchronized than desynchronized cortical state, contrary to reports in rodents. The open-ended, inclusive, high-dimensional experiments and analyses described here make few assumptions, potentially leading to more insightful theories of brain function than hypothesis-driven research alone.
Medicine, Faculty of
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Ranson, Adam. « Development and plasticity of the mouse primary visual cortex ». Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/54216/.

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A strain difference was observed in juvenile OD plasticity between C57BL/6J and C57BL/6JOlaHsd mice whereby open eye 'homeostatic' potentiation was completely absent in the C57BL/6JOlaHsd strain. This was accompanied by an absence of dark exposure induced synaptic scaling as measured ex vivo. In contrast in adulthood both strains showed comparable open eye potentiation, suggesting a mechanistic difference between juvenile and adult plasticity. Preliminary data suggests that while juvenile open eye potentiation is homeostatic, in adulthood it may be more LTP like and dependent upon CaMKII autophosphorylation.

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Livres sur le sujet "Primary Visual Cortex (PVC)"

Peters, Alan, et Kathleen S. Rockland, dir. Primary Visual Cortex in Primates. Boston, MA : Springer US, 1994. http://dx.doi.org/10.1007/978-1-4757-9628-5.

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1929-, Peters Alan, et Rockland, Kathleen Linda Skiba, 1947-, dir. Primary visual cortex in primates. New York : Plenum Press, 1994.

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1929-, Peters Alan, dir. The cat primary visual cortex. San Diego : Academic Press, 2002.

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Suner, Ivan Jose. Influences of the lateral geniculate nucleus in the specification of primary visual cortex in macaca mulatta. [s.l : s.n.], 1992.

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Rubin, Daniel Brett. A Novel Circuit Model of Contextual Modulation and Normalization in Primary Visual Cortex. [New York, N.Y.?] : [publisher not identified], 2012.

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service), SpringerLink (Online, dir. Circuits in the Brain : A Model of Shape Processing in the Primary Visual Cortex. New York, NY : Springer-Verlag New York, 2009.

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Ziskind, Avi. Neurons in Cat Primary Visual Cortex cluster by degree of tuning but not by absolute spatial phase or temporal response phase. [New York, N.Y.?] : [publisher not identified], 2013.

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Peters, Alan, et Bertram Payne. Cat Primary Visual Cortex. Elsevier Science & Technology Books, 2001.

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The Cat Primary Visual Cortex. Elsevier, 2002. http://dx.doi.org/10.1016/b978-0-12-552104-8.x5000-7.

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(Editor), Bertram Payne, et Alan Peters (Editor), dir. The Cat Primary Visual Cortex. Academic Press, 2001.

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Chapitres de livres sur le sujet "Primary Visual Cortex (PVC)"

Jinrong, Li. « Primary Visual Cortex ». Dans The ECPH Encyclopedia of Psychology, 1–2. Singapore : Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-6000-2_344-1.

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Kuljis, Rodrigo O. « The Human Primary Visual Cortex ». Dans Cerebral Cortex, 469–503. Boston, MA : Springer US, 1994. http://dx.doi.org/10.1007/978-1-4757-9628-5_12.

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Skalicky, Simon E. « The Primary Visual Cortex ». Dans Ocular and Visual Physiology, 207–18. Singapore : Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-287-846-5_14.

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Peters, Alan. « Number of Neurons and Synapses in Primary Visual Cortex ». Dans Cerebral Cortex, 267–94. Boston, MA : Springer US, 1987. http://dx.doi.org/10.1007/978-1-4615-6616-8_7.

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Peters, Alan. « The Organization of the Primary Visual Cortex in the Macaque ». Dans Cerebral Cortex, 1–35. Boston, MA : Springer US, 1994. http://dx.doi.org/10.1007/978-1-4757-9628-5_1.

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Casagrande, Vivien A., et Jon H. Kaas. « The Afferent, Intrinsic, and Efferent Connections of Primary Visual Cortex in Primates ». Dans Cerebral Cortex, 201–59. Boston, MA : Springer US, 1994. http://dx.doi.org/10.1007/978-1-4757-9628-5_5.

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Conway, Bevil R. « Segregated processing streams in primary visual cortex ». Dans neural mechanisms of Color Vision, 113–24. Boston, MA : Springer US, 2002. http://dx.doi.org/10.1007/978-1-4757-5953-2_4.

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Vascon, Sebastiano, Ylenia Parin, Eis Annavini, Mattia D’Andola, Davide Zoccolan et Marcello Pelillo. « Characterization of Visual Object Representations in Rat Primary Visual Cortex ». Dans Lecture Notes in Computer Science, 577–86. Cham : Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-11015-4_43.

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Frostig, Ron D. « What Does in Vivo Optical Imaging Tell Us about the Primary Visual Cortex in Primates ? » Dans Cerebral Cortex, 331–58. Boston, MA : Springer US, 1994. http://dx.doi.org/10.1007/978-1-4757-9628-5_8.

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Li, Zhaoping. « Pop-Out Theory : Segmentation Without Classification by the Primary Visual Cortex ». Dans Visual Attention Mechanisms, 69–78. Boston, MA : Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0111-4_7.

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Actes de conférences sur le sujet "Primary Visual Cortex (PVC)"

Günthner, Max F., Santiago A. Cadena, George H. Denfield, Edgar Y. Walker, Leon A. Gatys, Andreas S. Tolias, Matthias Bethge et Alexander S. Ecker. « Learning Divisive Normalization in Primary Visual Cortex ». Dans 2019 Conference on Cognitive Computational Neuroscience. Brentwood, Tennessee, USA : Cognitive Computational Neuroscience, 2019. http://dx.doi.org/10.32470/ccn.2019.1211-0.

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Tran, Thi Diem, Mutsumi Kimura et Yasuhiko Nakashima. « Primary Visual Cortex Inspired Feature Extraction Hardware Model ». Dans 2020 4th International Conference on Recent Advances in Signal Processing, Telecommunications & Computing (SigTelCom). IEEE, 2020. http://dx.doi.org/10.1109/sigtelcom49868.2020.9199057.

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Goto, Yoshinobu, Takao Yamasaki et Shozo Tobimatsu. « Innovation for visual stimuli : From the retina to primary visual cortex ». Dans 2010 IEEE/ICME International Conference on Complex Medical Engineering - CME 2010. IEEE, 2010. http://dx.doi.org/10.1109/iccme.2010.5558856.

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Bouganis, Christos-savvas, Peter K. Cheung et Li Zhaoping. « FPGA-Accelerated Pre-Attentive Segmentation in Primary Visual Cortex ». Dans 2006 International Conference on Field Programmable Logic and Applications. IEEE, 2006. http://dx.doi.org/10.1109/fpl.2006.311214.

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Maunsell, John H. R. « Motion processing in visual cortex ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.tuj2.

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Many lines of anatomical and physiological evidence have shown that the visual system contains a distinct pathway that is responsible for most motion analysis. In primates this pathway originates in the retinal ganglion cells that send their axons to the magnocellular layers of the lateral geniculate nucleus (LGN). The outputs from the magnocellular LGN layers directly provide the primary excitatory drive to structures like layer 4B in striate cortex and the middle temporal area (MT) in extrastriate cortex. Both of these structures contain a high proportion of neurons that are selective for the direction of stimulus motion. Later stages of motion processing in parietal cortex appear to contribute to analyzing more complex types of movement such as rotation or looming.

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Li, Ruyi, Ming Ke, Zhanguo Dong, Lubin Wang et Gang Wang. « Corruption-Robust Deep Convolutional Networks Inspired by Primary Visual Cortex ». Dans 2023 9th International Conference on Computer and Communications (ICCC). IEEE, 2023. http://dx.doi.org/10.1109/iccc59590.2023.10507252.

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Daniela, Coman Andreea, Ionita Silviu et Lita Ioan. « A Neuronal Model of the Primary Visual Cortex : Simulation of Visual Evoked Potentials ». Dans 2021 13th International Conference on Electronics, Computers and Artificial Intelligence (ECAI). IEEE, 2021. http://dx.doi.org/10.1109/ecai52376.2021.9515133.

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Festa, Dylan, Amir Aschner, Adam Kohn et Ruben Coen-Cagli. « A Functional Model of Neuronal Response Variability in Primary Visual Cortex ». Dans 2019 Conference on Cognitive Computational Neuroscience. Brentwood, Tennessee, USA : Cognitive Computational Neuroscience, 2019. http://dx.doi.org/10.32470/ccn.2019.1307-0.

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Yagi, Tetsuya, et Kazuhiro Shimonomura. « Silicon primary visual cortex designed with a mixed analog-digital architecture ». Dans 2007 International Joint Conference on Neural Networks. IEEE, 2007. http://dx.doi.org/10.1109/ijcnn.2007.4371389.

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Rajagopalan, Uma M., Hideyuki Takaoka, Ryota Homma, Hirofumi Kadono et Manabu Tanifuji. « Functional imaging of cat primary visual cortex with optical coherence tomography ». Dans International Symposium on Biomedical Optics, sous la direction de Valery V. Tuchin, Joseph A. Izatt et James G. Fujimoto. SPIE, 2002. http://dx.doi.org/10.1117/12.470474.

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