Articles de revues : « Visual cortical areas »

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Pollen, Daniel A. « Cortical areas in visual awareness ». Nature 377, n^o 6547 (septembre 1995) : 293–94. http://dx.doi.org/10.1038/377293b0.

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Crick, Francis, et Christof Koch. « Cortical areas in visual awareness ». Nature 377, n^o 6547 (septembre 1995) : 294–95. http://dx.doi.org/10.1038/377294a0.

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Kallenberger, S., C. Schmidt, T. Wustenberg et H. Strasburger. « Visual Fusion and Binocular Rivalry in Cortical Visual Areas ». Journal of Vision 10, n^o 7 (3 août 2010) : 360. http://dx.doi.org/10.1167/10.7.360.

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Vanni, S., L. Henriksson et A. C. James. « Multifocal fMRI mapping of visual cortical areas ». NeuroImage 27, n^o 1 (août 2005) : 95–105. http://dx.doi.org/10.1016/j.neuroimage.2005.01.046.

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Yue, Xiaomin, Sophia Robert et Leslie G. Ungerleider. « Curvature processing in human visual cortical areas ». NeuroImage 222 (novembre 2020) : 117295. http://dx.doi.org/10.1016/j.neuroimage.2020.117295.

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Cortes, Nelson, Bruno O. F. de Souza et Christian Casanova. « Pulvinar Modulates Synchrony across Visual Cortical Areas ». Vision 4, n^o 2 (10 avril 2020) : 22. http://dx.doi.org/10.3390/vision4020022.

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The cortical visual hierarchy communicates in different oscillatory ranges. While gamma waves influence the feedforward processing, alpha oscillations travel in the feedback direction. Little is known how this oscillatory cortical communication depends on an alternative route that involves the pulvinar nucleus of the thalamus. We investigated whether the oscillatory coupling between the primary visual cortex (area 17) and area 21a depends on the transthalamic pathway involving the pulvinar in cats. To that end, visual evoked responses were recorded in areas 17 and 21a before, during and after inactivation of the pulvinar. Local field potentials were analyzed with Wavelet and Granger causality tools to determine the oscillatory coupling between layers. The results indicate that cortical oscillatory activity was enhanced during pulvinar inactivation, in particular for area 21a. In area 17, alpha band responses were represented in layers II/III. In area 21a, gamma oscillations, except for layer I, were significantly increased, especially in layer IV. Granger causality showed that the pulvinar modulated the oscillatory information between areas 17 and 21a in gamma and alpha bands for the feedforward and feedback processing, respectively. Together, these findings indicate that the pulvinar is involved in the mechanisms underlying oscillatory communication along the visual cortex.

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Benoliel, Tal, Noa Raz, Tamir Ben-Hur et Netta Levin. « Cortical functional modifications following optic neuritis ». Multiple Sclerosis Journal 23, n^o 2 (11 juillet 2016) : 220–27. http://dx.doi.org/10.1177/1352458516649677.

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Background: We have recently suggested that delayed visual evoked potential (VEP) latencies in the fellow eye (FE) of optic neuritis patients reflect a cortical adaptive process, to compensate for the delayed arrival of visual information via the affected eye (AE). Objective: To define the cortical mechanism that underlies this adaptive process. Methods: Cortical activations to moving stimuli and connectivity patterns within the visual network were tested using functional magnetic resonance imaging (MRI) in 11 recovered optic neuritis patients and in 11 matched controls. Results: Reduced cortical activation in early but not in higher visual areas was seen in both eyes, compared to controls. VEP latencies in the AEs inversely correlated with activation in motion-related visual cortices. Inter-eye differences in VEP latencies inversely correlated with cortical activation following FE stimulation, throughout the visual hierarchy. Functional correlation between visual regions was more pronounced in the FE compared with the AE. Conclusion: The different correlation patterns between VEP latencies and cortical activation in the AE and FE support different pathophysiology of VEP prolongation in each eye. Similar cortical activation patterns in both eyes and the fact that stronger links between early and higher visual areas were found following FE stimulation suggest a cortical modulatory process in the FE.

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Smith, Ikuko T., Leah B. Townsend, Ruth Huh, Hongtu Zhu et Spencer L. Smith. « Stream-dependent development of higher visual cortical areas ». Nature Neuroscience 20, n^o 2 (9 janvier 2017) : 200–208. http://dx.doi.org/10.1038/nn.4469.

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Yue, Xiaomin, Amisha Gandhi et Leslie Ungerleider. « Curvature-biased cortical areas in human visual cortex ». Journal of Vision 15, n^o 12 (1 septembre 2015) : 625. http://dx.doi.org/10.1167/15.12.625.

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Andermann, Mark L., Aaron M. Kerlin, Demetris K. Roumis, Lindsey L. Glickfeld et R. Clay Reid. « Functional Specialization of Mouse Higher Visual Cortical Areas ». Neuron 72, n^o 6 (décembre 2011) : 1025–39. http://dx.doi.org/10.1016/j.neuron.2011.11.013.

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Marshel, James H., Marina E. Garrett, Ian Nauhaus et Edward M. Callaway. « Functional Specialization of Seven Mouse Visual Cortical Areas ». Neuron 72, n^o 6 (décembre 2011) : 1040–54. http://dx.doi.org/10.1016/j.neuron.2011.12.004.

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Alvarez, Ivan, Andrew J. Parker et Holly Bridge. « Normative cerebral cortical thickness for human visual areas ». NeuroImage 201 (novembre 2019) : 116057. http://dx.doi.org/10.1016/j.neuroimage.2019.116057.

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Gattass, Ricardo, Sheila Nascimento-Silva, Juliana G. M. Soares, Bruss Lima, Ana Karla Jansen, Antonia Cinira M. Diogo, Mariana F. Farias et al. « Cortical visual areas in monkeys : location, topography, connections, columns, plasticity and cortical dynamics ». Philosophical Transactions of the Royal Society B : Biological Sciences 360, n^o 1456 (29 avril 2005) : 709–31. http://dx.doi.org/10.1098/rstb.2005.1629.

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The visual system is constantly challenged to organize the retinal pattern of stimulation into coherent percepts. This task is achieved by the cortical visual system, which is composed by topographically organized analytic areas and by synthetic areas of the temporal lobe that have more holistic processing. Additional visual areas of the parietal lobe are related to motion perception and visuomotor control. V1 and V2 represent the entire visual field. MT represents only the binocular field, and V4 only the central 30°–40°. The parietal areas represent more of the periphery. For any eccentricity, the receptive field grows at each step of processing, more at anterior areas in the temporal lobe. Minimal point image size increases towards the temporal lobe, but remains fairly constant toward the parietal lobe. Patterns of projection show asymmetries. Central V2 and V4 project mainly to the temporal lobe, while peripherals V2 (more than 30°) and V4 (more than 10°) also project to the parietal lobe. Visual information that arrives at V1 projects to V2, MT and PO, which then project to other areas. Local lateral propagation and recursive loops corroborate to perceptual completion and filling in. Priority connections to temporal, parietal and parieto-temporal cortices help construct crude early representations of objects, trajectories and movements.

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Duménieu, Maël, Béatrice Marquèze-Pouey, Michaël Russier et Dominique Debanne. « Mechanisms of Plasticity in Subcortical Visual Areas ». Cells 10, n^o 11 (13 novembre 2021) : 3162. http://dx.doi.org/10.3390/cells10113162.

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Visual plasticity is classically considered to occur essentially in the primary and secondary cortical areas. Subcortical visual areas such as the dorsal lateral geniculate nucleus (dLGN) or the superior colliculus (SC) have long been held as basic structures responsible for a stable and defined function. In this model, the dLGN was considered as a relay of visual information travelling from the retina to cortical areas and the SC as a sensory integrator orienting body movements towards visual targets. However, recent findings suggest that both dLGN and SC neurons express functional plasticity, adding unexplored layers of complexity to their previously attributed functions. The existence of neuronal plasticity at the level of visual subcortical areas redefines our approach of the visual system. The aim of this paper is therefore to review the cellular and molecular mechanisms for activity-dependent plasticity of both synaptic transmission and cellular properties in subcortical visual areas.

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Convento, Silvia, Giuseppe Vallar, Chiara Galantini et Nadia Bolognini. « Neuromodulation of Early Multisensory Interactions in the Visual Cortex ». Journal of Cognitive Neuroscience 25, n^o 5 (mai 2013) : 685–96. http://dx.doi.org/10.1162/jocn_a_00347.

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Merging information derived from different sensory channels allows the brain to amplify minimal signals to reduce their ambiguity, thereby improving the ability of orienting to, detecting, and identifying environmental events. Although multisensory interactions have been mostly ascribed to the activity of higher-order heteromodal areas, multisensory convergence may arise even in primary sensory-specific areas located very early along the cortical processing stream. In three experiments, we investigated early multisensory interactions in lower-level visual areas, by using a novel approach, based on the coupling of behavioral stimulation with two noninvasive brain stimulation techniques, namely, TMS and transcranial direct current stimulation (tDCS). First, we showed that redundant multisensory stimuli can increase visual cortical excitability, as measured by means of phosphene induction by occipital TMS; such physiological enhancement is followed by a behavioral facilitation through the amplification of signal intensity in sensory-specific visual areas. The more sensory inputs are combined (i.e., trimodal vs. bimodal stimuli), the greater are the benefits on phosphene perception. Second, neuroelectrical activity changes induced by tDCS in the temporal and in the parietal cortices, but not in the occipital cortex, can further boost the multisensory enhancement of visual cortical excitability, by increasing the auditory and tactile inputs from temporal and parietal regions, respectively, to lower-level visual areas.

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Minini, Loredana, Andrew J. Parker et Holly Bridge. « Neural Modulation by Binocular Disparity Greatest in Human Dorsal Visual Stream ». Journal of Neurophysiology 104, n^o 1 (juillet 2010) : 169–78. http://dx.doi.org/10.1152/jn.00790.2009.

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Although cortical activation to binocular disparity can be demonstrated throughout occipital and parietal cortices, the relative contributions to depth perception made by different human cortical areas have not been established. To investigate whether different regions are optimized for specific disparity ranges, we have measured the responses of occipital and parietal areas to different magnitudes of binocular disparity. Using stimuli consisting of sinusoidal depth modulations, we measured cortical activation when the stimuli were located at pedestal disparities of 0, 0.1, 0.35, and 0.7° from fixation. Across all areas, occipital and parietal, there was an increase in BOLD signal with increasing pedestal disparity, compared with a plane at zero disparity. However, the greatest modulation of response by the different pedestals was found in the dorsal visual areas and the parietal areas. These differences contrast with the response to the zero disparity plane, compared with fixation, which is greatest in the early visual areas, smaller in the ventral and dorsal visual areas, and absent in parietal areas. Using the simultaneously acquired psychophysical data we also measured a greater response to correct than to incorrect trials, an effect that increased with rising pedestal disparity and was greatest in dorsal visual and parietal areas. These results illustrate that the dorsal stream, along both its occipital and parietal branches, can reliably discriminate a large range of disparities.

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Morel, Anne, et Jean Bullier. « Anatomical segregation of two cortical visual pathways in the macaque monkey ». Visual Neuroscience 4, n^o 6 (juin 1990) : 555–78. http://dx.doi.org/10.1017/s0952523800005769.

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AbstractA number of lines of evidence suggest that, in the macaque monkey, inferior parietal and inferotemporal cortices process different types of visual information. It has been suggested that visual information reaching these two subdivisions follows separate pathways from the striate cortex through the prestriate cortex. We examined directly this possibility by placing injections of the retrograde fluorescent tracers, fast blue and diamidino yellow, in inferior parietal and inferotemporal cortex and examining the spatial pattern of cortical areas containing labeled cells in two-dimensional reconstructions of the cortex.The results of injections in inferotemporal cortex show that TEO receives afferents from areas V2, ventral V3, V3A, central V4, V4t, and DPL in prestriate cortex and from areas IPa, PGa, and FST in the superior temporal sulcus (STS). Area TEp receives afferents only from V4 in prestriate cortex and from IPa, PGa, and FST in the anterior STS. Area TEa receives no prestriate input and is innervated by IPa, PGa, FST, and TPO in the anterior STS.The results of injections in inferior parietal cortex demonstrate that POa receives afferents from dorsal V3, V3A, peripheral V4, DPL, and PO in prestriate cortex, from MST and *VIP and from IPa, PGa, TPO, and FST in anterior STS. Area PGc (corresponding to 7a) is innervated by PO, MST, and by TPO in the anterior STS.Examination of the two-dimensional reconstructions of the pattern of labeling after combined injections of fast blue and diamidino yellow in areas POa and TEO revealed that these areas are principally innervated by different prestriate areas. Only a small region, centered on area V3A and extending into V4 and DPL, contained cells labeled by either injection as well as a small number of double-labeled cells. In contrast, areas POa and TEO receive afferents from extensive common regions in the anterior STS corresponding to areas IPa, PGa, and FST.These results directly demonstrate that visual information from the striate cortex reaches inferior parietal and inferotemporal cortices through largely separate prestriate cortical pathways. On the other hand, both parietal and inferotemporal cortices receive common inputs from extensive regions in the anterior STS which may play a role in linking the processing occurring in these two cortical subdivisions of the visual system.

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Yaka, Rami, Uri Yinon et Zvi Wollberg. « Auditory activation of cortical visual areas in cats after early visual deprivation ». European Journal of Neuroscience 11, n^o 4 (avril 1999) : 1301–12. http://dx.doi.org/10.1046/j.1460-9568.1999.00536.x.

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Jang, Hojin, et Frank Tong. « Visual crowding disrupts the cortical representation of letters in early visual areas ». Journal of Vision 19, n^o 10 (6 septembre 2019) : 65c. http://dx.doi.org/10.1167/19.10.65c.

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Yabuta, N. H. « Two Functional Channels from Primary Visual Cortex to Dorsal Visual Cortical Areas ». Science 292, n^o 5515 (13 avril 2001) : 297–300. http://dx.doi.org/10.1126/science.1057916.

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Krauzlis, Richard J. « Visual Neuroscience : What to Do with All of These Cortical Visual Areas ? » Current Biology 30, n^o 23 (décembre 2020) : R1428—R1431. http://dx.doi.org/10.1016/j.cub.2020.09.059.

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Murray, Scott O., Paul Schrater et Daniel Kersten. « Perceptual grouping and the interactions between visual cortical areas ». Neural Networks 17, n^o 5-6 (juin 2004) : 695–705. http://dx.doi.org/10.1016/j.neunet.2004.03.010.

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Ruff, D. A., et M. R. Cohen. « Attention Increases Spike Count Correlations between Visual Cortical Areas ». Journal of Neuroscience 36, n^o 28 (13 juillet 2016) : 7523–34. http://dx.doi.org/10.1523/jneurosci.0610-16.2016.

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Rosa, Marcello G. P., et Rowan Tweedale. « Brain maps, great and small : lessons from comparative studies of primate visual cortical organization ». Philosophical Transactions of the Royal Society B : Biological Sciences 360, n^o 1456 (29 avril 2005) : 665–91. http://dx.doi.org/10.1098/rstb.2005.1626.

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In this paper, we review evidence from comparative studies of primate cortical organization, highlighting recent findings and hypotheses that may help us to understand the rules governing evolutionary changes of the cortical map and the process of formation of areas during development. We argue that clear unequivocal views of cortical areas and their homologies are more likely to emerge for ‘core’ fields, including the primary sensory areas, which are specified early in development by precise molecular identification steps. In primates, the middle temporal area is probably one of these primordial cortical fields. Areas that form at progressively later stages of development correspond to progressively more recent evolutionary events, their development being less firmly anchored in molecular specification. The certainty with which areal boundaries can be delimited, and likely homologies can be assigned, becomes increasingly blurred in parallel with this evolutionary/developmental sequence. For example, while current concepts for the definition of cortical areas have been vindicated in allowing a clarification of the organization of the New World monkey ‘third tier’ visual cortex (the third and dorsomedial areas, V3 and DM), our analyses suggest that more flexible mapping criteria may be needed to unravel the organization of higher-order visual association and polysensory areas.

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Brecht, Michael, Wolf Singer et Andreas K. Engel. « Correlation Analysis of Corticotectal Interactions in the Cat Visual System ». Journal of Neurophysiology 79, n^o 5 (1 mai 1998) : 2394–407. http://dx.doi.org/10.1152/jn.1998.79.5.2394.

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Brecht, Michael, Wolf Singer, and Andreas K. Engel. Correlation analysis of corticotectal interactions in the cat visual system. J. Neurophysiol. 79: 2394–2407, 1998. We have studied the temporal relationship between visual responses in various visual cortical areas [17, 18, postero medial lateral suprasylvian (PMLS), postero lateral lateral suprasylvian (PLLS), 21a]) and the superficial layers of the cat superior colliculus (SC). To this end, simultaneous recordings were performed in one or several visual cortical areas and the SC of anesthetized paralyzed cats, and visually evoked multiunit responses were subjected to correlation analysis. Significant correlations occurred in 117 (24%) of 489 cortex-SC pairs and were found for all cortical areas recorded. About half of the significant correlograms showed an oscillatory modulation. In these cases, oscillation frequencies covered a broad range, the majority being in the alpha- and beta-band. On average, significant center peaks in cross-correlograms had a modulation amplitude of 0.34. Our analysis revealed a considerable intertrial variability of correlation patterns with respect to both correlation strength and oscillation frequency. Furthermore, cortical areas differed in their corticotectal correlation patterns. The percentage of cells involved a corticotectal correlation, as well as the percentage of significantly modulated correlograms in such cases, was low for areas 17 and PMLS but high for areas 18 and PLLS. Analysis of the cortical layers involved in these interactions showed that consistent temporal relationships between cortical and collicular responses were not restricted to layer V. Our data demonstrate a close relationship between corticotectal interactions and intracortical or intracollicular synchronization. Trial-by-trial analysis from these sites revealed a clear covariance of corticotectal correlations with intracortical synchronization. The probability of observing corticotectal interactions increased with enhanced local cortical and collicular synchronization and, in particular, with interareal cortical correlations. Corticotectal correlation patterns resemble in many ways those described among areas of the visual cortex. However, the correlations observed are weaker than those between nearby cortical sites, exhibit usually broader peaks and for some cortical areas show consistent phase-shifts. Corticotectal correlations represent population phenomena that reflect both the local and global temporal organization of activity in the cortical and collicular network and do not arise from purely monosynaptic interactions. Our findings show that both striate and extrastriate inputs affect the superficial SC in a cooperative manner and, thus, do not support the view that responses in the superficial SC depend exclusively on input from the primary visual areas as implied by the concept of “two corticotectal systems.” We conclude that the corticotectal projections convey temporal activation patterns with high reliability, thus allowing the SC evaluation of information encoded in the temporal relations between responses of spatially disseminated cortical neurons. As a consequence, information distributed across multiple cortical areas can affect the SC neurons in a coherent way.

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GILBERT, CHARLES D. « Adult Cortical Dynamics ». Physiological Reviews 78, n^o 2 (1 avril 1998) : 467–85. http://dx.doi.org/10.1152/physrev.1998.78.2.467.

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Gilbert, Charles D. Adult Cortical Dynamics. Physiol. Rev. 78: 467–485, 1998. — There are many influences on our perception of local features. What we see is not strictly a reflection of the physical characteristics of a scene but instead is highly dependent on the processes by which our brain attempts to interpret the scene. As a result, our percepts are shaped by the context within which local features are presented, by our previous visual experiences, operating over a wide range of time scales, and by our expectation of what is before us. The substrate for these influences is likely to be found in the lateral interactions operating within individual areas of the cerebral cortex and in the feedback from higher to lower order cortical areas. Even at early stages in the visual pathway, cells are far more flexible in their functional properties than previously thought. It had long been assumed that cells in primary visual cortex had fixed properties, passing along the product of a stereotyped operation to the next stage in the visual pathway. Any plasticity dependent on visual experience was thought to be restricted to a period early in the life of the animal, the critical period. Furthermore, the assembly of contours and surfaces into unified percepts was assumed to take place at high levels in the visual pathway, whereas the receptive fields of cells in primary visual cortex represented very small windows on the visual scene. These concepts of spatial integration and plasticity have been radically modified in the past few years. The emerging view is that even at the earliest stages in the cortical processing of visual information, cells are highly mutable in their functional properties and are capable of integrating information over a much larger part of visual space than originally believed.

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Gückel, F., M. E. Bellemann, J. Röther, A. Schwartz, H. J. Ostertag, W. J. Lorenz et G. Brix. « Functional MR Mapping of Activated Cortical Areas ». Nuklearmedizin 33, n^o 05 (1994) : 200–205. http://dx.doi.org/10.1055/s-0038-1629755.

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SummaryMagnetic resonance imaging (MRI) has recently been demonstrated to be sensitive to changes in neuronal activity of cortical areas. We report our initial experiences with functional MR brain mapping at high spatial resolution using a conventional whole-body MR system. A total of 10 visual and motor cortex activation studies were carried out on 8 healthy volunteers. In each examination, a time course series of 15 strongly T2*-weighted FLASH images was measured from three adjacent slices. The image analysis revealed a subtle but highly significant signal increase in cortical layers of gray matter in primary and associative visual as well as sensorimotoric cortex regions during periods of excessive brain activity provoked by photic stimuli or motoric tasks, respectively. To correlate brain structure and brain function, the computed MR brain activation maps were directly superimposed on T1-weighted anatomic spin-echo images. With this advance into the area of functional neuroimaging, MRI is moving into an established domain of positron emission tomography (PET). We, therefore, discuss the advantages and limitations of the MR method in comparison to PET as far as this can be done at present.

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Kumar, Mari Ganesh, Ming Hu, Aadhirai Ramanujan, Mriganka Sur et Hema A. Murthy. « Functional parcellation of mouse visual cortex using statistical techniques reveals response-dependent clustering of cortical processing areas ». PLOS Computational Biology 17, n^o 2 (4 février 2021) : e1008548. http://dx.doi.org/10.1371/journal.pcbi.1008548.

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The visual cortex of the mouse brain can be divided into ten or more areas that each contain complete or partial retinotopic maps of the contralateral visual field. It is generally assumed that these areas represent discrete processing regions. In contrast to the conventional input-output characterizations of neuronal responses to standard visual stimuli, here we asked whether six of the core visual areas have responses that are functionally distinct from each other for a given visual stimulus set, by applying machine learning techniques to distinguish the areas based on their activity patterns. Visual areas defined by retinotopic mapping were examined using supervised classifiers applied to responses elicited by a range of stimuli. Using two distinct datasets obtained using wide-field and two-photon imaging, we show that the area labels predicted by the classifiers were highly consistent with the labels obtained using retinotopy. Furthermore, the classifiers were able to model the boundaries of visual areas using resting state cortical responses obtained without any overt stimulus, in both datasets. With the wide-field dataset, clustering neuronal responses using a constrained semi-supervised classifier showed graceful degradation of accuracy. The results suggest that responses from visual cortical areas can be classified effectively using data-driven models. These responses likely reflect unique circuits within each area that give rise to activity with stronger intra-areal than inter-areal correlations, and their responses to controlled visual stimuli across trials drive higher areal classification accuracy than resting state responses.

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de Souza, Bruno Oliveira Ferreira, Nelson Cortes et Christian Casanova. « Pulvinar Modulates Contrast Responses in the Visual Cortex as a Function of Cortical Hierarchy ». Cerebral Cortex 30, n^o 3 (13 août 2019) : 1068–86. http://dx.doi.org/10.1093/cercor/bhz149.

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Abstract The pulvinar is the largest extrageniculate visual nucleus in mammals. Given its extensive reciprocal connectivity with the visual cortex, it allows the cortico-thalamocortical transfer of visual information. Nonetheless, knowledge of the nature of the pulvinar inputs to the cortex remains elusive. We investigated the impact of silencing the pulvinar on the contrast response function of neurons in 2 distinct hierarchical cortical areas in the cat (areas 17 and 21a). Pulvinar inactivation altered the response gain in both areas, but with larger changes observed in area 21a. A theoretical model was proposed, simulating the pulvinar contribution to cortical contrast responses by modifying the excitation-inhibition balanced state of neurons across the cortical hierarchy. Our experimental and theoretical data showed that the pulvinar exerts a greater modulatory influence on neuronal activity in area 21a than in the primary visual cortex, indicating that the pulvinar impact on cortical visual neurons varies along the cortical hierarchy.

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Merabet, Lotfi B., Jascha D. Swisher, Stephanie A. McMains, Mark A. Halko, Amir Amedi, Alvaro Pascual-Leone et David C. Somers. « Combined Activation and Deactivation of Visual Cortex During Tactile Sensory Processing ». Journal of Neurophysiology 97, n^o 2 (février 2007) : 1633–41. http://dx.doi.org/10.1152/jn.00806.2006.

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The involvement of occipital cortex in sensory processing is not restricted solely to the visual modality. Tactile processing has been shown to modulate higher-order visual and multisensory integration areas in sighted as well as visually deprived subjects; however, the extent of involvement of early visual cortical areas remains unclear. To investigate this issue, we employed functional magnetic resonance imaging in normally sighted, briefly blindfolded subjects with well-defined visuotopic borders as they tactually explored and rated raised-dot patterns. Tactile task performance resulted in significant activation in primary visual cortex (V1) and deactivation of extrastriate cortical regions V2, V3, V3A, and hV4 with greater deactivation in dorsal subregions and higher visual areas. These results suggest that tactile processing affects occipital cortex via two distinct pathways: a suppressive top-down pathway descending through the visual cortical hierarchy and an excitatory pathway arising from outside the visual cortical hierarchy that drives area V1 directly.

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Lennie, Peter. « Single Units and Visual Cortical Organization ». Perception 27, n^o 8 (août 1998) : 889–935. http://dx.doi.org/10.1068/p270889.

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The visual system has a parallel and hierarchical organization, evident at every stage from the retina onwards. Although the general benefits of parallel and hierarchical organization in the visual system are easily understood, it has not been easy to discern the function of the visual cortical modules. I explore the view that striate cortex segregates information about different attributes of the image, and dispatches it for analysis to different extrastriate areas. I argue that visual cortex does not undertake multiple relatively independent analyses of the image from which it assembles a unified representation that can be interrogated about the what and where of the world. Instead, occipital cortex is organized so that perceptually relevant information can be recovered at every level in the hierarchy, that information used in making decisions at one level is not passed on to the next level, and, with one rather special exception (area MT), through all stages of analysis all dimensions of the image remain intimately coupled in a retinotopic map. I then offer some explicit suggestions about the analyses undertaken by visual areas in occipital cortex, and conclude by examining some objections to the proposals.

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Kriegstein, Katharina von, Andreas Kleinschmidt, Philipp Sterzer et Anne-Lise Giraud. « Interaction of Face and Voice Areas during Speaker Recognition ». Journal of Cognitive Neuroscience 17, n^o 3 (mars 2005) : 367–76. http://dx.doi.org/10.1162/0898929053279577.

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Face and voice processing contribute to person recognition, but it remains unclear how the segregated specialized cortical modules interact. Using functional neuroimaging, we observed cross-modal responses to voices of familiar persons in the fusiform face area, as localized separately using visual stimuli. Voices of familiar persons only activated the face area during a task that emphasized speaker recognition over recognition of verbal content. Analyses of functional connectivity between cortical territories show that the fusiform face region is coupled with the superior temporal sulcus voice region during familiar speaker recognition, but not with any of the other cortical regions normally active in person recognition or in other tasks involving voices. These findings are relevant for models of the cognitive processes and neural circuitry involved in speaker recognition. They reveal that in the context of speaker recognition, the assessment of person familiarity does not necessarily engage supra-modal cortical substrates but can result from the direct sharing of information between auditory voice and visual face regions.

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Zeri, Fabrizio, Marika Berchicci, Shehzad A. Naroo, Sabrina Pitzalis et Francesco Di Russo. « Immediate cortical adaptation in visual and non-visual areas functions induced by monovision ». Journal of Physiology 596, n^o 2 (15 novembre 2017) : 253–66. http://dx.doi.org/10.1113/jp274896.

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Huk, Alexander C., et David J. Heeger. « Task-Related Modulation of Visual Cortex ». Journal of Neurophysiology 83, n^o 6 (1 juin 2000) : 3525–36. http://dx.doi.org/10.1152/jn.2000.83.6.3525.

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We performed a series of experiments to quantify the effects of task performance on cortical activity in early visual areas. Functional magnetic resonance imaging (fMRI) was used to measure cortical activity in several cortical visual areas including primary visual cortex (V1) and the MT complex (MT+) as subjects performed a variety of threshold-level visual psychophysical tasks. Performing speed, direction, and contrast discrimination tasks produced strong modulations of cortical activity. For example, one experiment tested for selective modulations of MT+ activity as subjects alternated between performing contrast and speed discrimination tasks. MT+ responses modulated in phase with the periods of time during which subjects performed the speed discrimination task; that is, MT+ activity was higher during speed discrimination than during contrast discrimination. Task-related modulations were consistent across repeated measurements in each subject; however, significant individual differences were observed between subjects. Together, the results suggest 1) that specific changes in the cognitive/behavioral state of a subject can exert selective and reliable modulations of cortical activity in early visual cortex, even in V1; 2) that there are significant individual differences in these modulations; and 3) that visual areas and pathways that are highly sensitive to small changes in a given stimulus feature (such as contrast or speed) are selectively modulated during discrimination judgments on that feature. Increasing the gain of the relevant neuronal signals in this way may improve their signal-to-noise to help optimize task performance.

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Putnam, Mary Colvin, Megan S. Steven, Karl W. Doron, Adam C. Riggall et Michael S. Gazzaniga. « Cortical Projection Topography of the Human Splenium : Hemispheric Asymmetry and Individual Differences ». Journal of Cognitive Neuroscience 22, n^o 8 (août 2010) : 1662–69. http://dx.doi.org/10.1162/jocn.2009.21290.

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The corpus callosum is the largest white matter pathway in the human brain. The most posterior portion, known as the splenium, is critical for interhemispheric communication between visual areas. The current study employed diffusion tensor imaging to delineate the complete cortical projection topography of the human splenium. Homotopic and heterotopic connections were revealed between the splenium and the posterior visual areas, including the occipital and the posterior parietal cortices. In nearly one third of participants, there were homotopic connections between the primary visual cortices, suggesting interindividual differences in splenial connectivity. There were also more instances of connections with the right hemisphere, indicating a hemispheric asymmetry in interhemispheric connectivity within the splenium. Combined, these findings demonstrate unique aspects of human interhemispheric connectivity and provide anatomical bases for hemispheric asymmetries in visual processing and a long-described hemispheric asymmetry in speed of interhemispheric communication for visual information.

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Tootell, R. B. H., A. M. Dale, N. Hadjikhani, A. K. Liu, S. Marrett et J. D. Mendola. « Functional Organisation of Human Visual Cortex Revealed by fMRI ». Perception 26, n^o 1_suppl (août 1997) : 9. http://dx.doi.org/10.1068/v970007.

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Until recently, comparatively little was known about the functional organisation of human visual cortex. Functional magnetic resonance imaging (fMRI), in conjunction with cortical flattening techniques and psychophysically relevant visual stimulation, has greatly clarified human visual-information processing. To date, we have completed cortical surface reconstructions (flattening), coupled with a wide range of visual stimulus testing, on 28 normal human subjects. Visual activation was acquired on a 1.5 T GE MR scanner with ANMR echo-planar imaging, with the use of a custom, bilateral, quadrature surface coil covering posterior cortex. Approximately ten visual cortical areas can now be functionally localised each with unique functional and topographical properties. The most well-defined areas are: V1, V2, V3, VP, V3A, V4v, MT, SPO, and perhaps MSTd. Most of the properties in these human areas are similar to those reported in presumably homologous areas of macaque, but distinctive species differences also appear to exist, notably in V3/VP, V4v, and V3A. Human areas showing prominant motion-selectivity include V3A, MT/MSTd, SPO, and a small area near the superior sylvian fissure. Retinotopic areas include V1, V2, V3, VP, V4v, and V3A. The human cortical magnification factor appears higher towards the fovea than in macaque, but, like macaque, preferred spatial frequency tuning varies inversely with eccentricity in all retinotopic areas in which sinusoidal gratings are effective stimuli.

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Webster, Maree J., Leslie G. Ungerleider et Jocelyne Bachevalier. « Development and plasticity of the neural circuitry underlying visual recognition memory ». Canadian Journal of Physiology and Pharmacology 73, n^o 9 (1 septembre 1995) : 1364–71. http://dx.doi.org/10.1139/y95-191.

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In adult monkeys, visual recognition memory, as measured by the delayed nonmatching to sample (DNMS) task, requires the interaction between inferior temporal cortical area TE and medial temporal lobe structures (mainly the entorhinal and perirhinal cortical areas). Ontogenetically, monkeys do not perform at adult levels of proficiency on the DNMS task until 2 years of age. Recent studies have demonstrated that this protracted development of visual recognition memory is due to an immaturity of the association areas of the neocortex rather than the medial temporal lobe. For example, lesions of the medial temporal lobe structures in infancy or in adulthood yield profound and permanent visual recognition loss, indicating that the medial temporal lobe structures operate early in life to sustain visual memory. In contrast, early lesions of area TE, unlike late lesions, result in a significant and long-lasting sparing of visual memory ability. Further evidence for neocortical immaturity is provided by studies of the development of opiatergic and cholinergic receptors, of the maturation of metabolic activity, and of the connectivity between inferior temporal areas TE and TEO and cortical and subcortical structures. Together these results indicate greater compensatory potential after neonatal cortical than after neonatal medial temporal removals. In support of this view, early damage to area TE leads to the maintenance of normally transient projections as well as to reorganization in cortical areas outside the temporal lobe. In addition, lesion studies indicate that, during infancy, visual recognition functions are widely distributed throughout many visual association areas but, with maturation, these functions become localized to area TE. Thus, the maintenance of exuberant projections together with reorganization in other cortical areas of the brain could account for the preservation of visual memories in monkeys that have had area TE removed in infancy.Key words: limbic structures, association cortex, amygdala, transient connections, compensatory potential.

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Danka Mohammed, Chand Parvez. « Differential Circuit Mechanisms of Young and Aged Visual Cortex in the Mammalian Brain ». NeuroSci 2, n^o 1 (4 janvier 2021) : 1–26. http://dx.doi.org/10.3390/neurosci2010001.

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The main goal of this review is to summarize and discuss (1) age-dependent structural reorganization of mammalian visual cortical circuits underlying complex visual behavior functions in primary visual cortex (V1) and multiple extrastriate visual areas, and (2) current evidence supporting the notion of compensatory mechanisms in aged visual circuits as well as the use of rehabilitative therapy for the recovery of neural plasticity in normal and diseased aging visual circuit mechanisms in different species. It is well known that aging significantly modulates both the structural and physiological properties of visual cortical neurons in V1 and other visual cortical areas in various species. Compensatory aged neural mechanisms correlate with the complexity of visual functions; however, they do not always result in major circuit alterations resulting in age-dependent decline in performance of a visual task or neurodegenerative disorders. Computational load and neural processing gradually increase with age, and the complexity of compensatory mechanisms correlates with the intricacy of higher form visual perceptions that are more evident in higher-order visual areas. It is particularly interesting to note that the visual perceptual processing of certain visual behavior functions does not change with age. This review aims to comprehensively discuss the effect of normal aging on neuroanatomical alterations that underlie critical visual functions and more importantly to highlight differences between compensatory mechanisms in aged neural circuits and neural processes related to visual disorders. This type of approach will further enhance our understanding of inter-areal and cortico-cortical connectivity of visual circuits in normal aging and identify major circuit alterations that occur in different visual deficits, thus facilitating the design and evaluation of potential rehabilitation therapies as well as the assessment of the extent of their rejuvenation.

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Chen, Nihong, Peng Cai, Tiangang Zhou, Benjamin Thompson et Fang Fang. « Perceptual learning modifies the functional specializations of visual cortical areas ». Proceedings of the National Academy of Sciences 113, n^o 20 (5 avril 2016) : 5724–29. http://dx.doi.org/10.1073/pnas.1524160113.

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Training can improve performance of perceptual tasks. This phenomenon, known as perceptual learning, is strongest for the trained task and stimulus, leading to a widely accepted assumption that the associated neuronal plasticity is restricted to brain circuits that mediate performance of the trained task. Nevertheless, learning does transfer to other tasks and stimuli, implying the presence of more widespread plasticity. Here, we trained human subjects to discriminate the direction of coherent motion stimuli. The behavioral learning effect substantially transferred to noisy motion stimuli. We used transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) to investigate the neural mechanisms underlying the transfer of learning. The TMS experiment revealed dissociable, causal contributions of V3A (one of the visual areas in the extrastriate visual cortex) and MT+ (middle temporal/medial superior temporal cortex) to coherent and noisy motion processing. Surprisingly, the contribution of MT+ to noisy motion processing was replaced by V3A after perceptual training. The fMRI experiment complemented and corroborated the TMS finding. Multivariate pattern analysis showed that, before training, among visual cortical areas, coherent and noisy motion was decoded most accurately in V3A and MT+, respectively. After training, both kinds of motion were decoded most accurately in V3A. Our findings demonstrate that the effects of perceptual learning extend far beyond the retuning of specific neural populations for the trained stimuli. Learning could dramatically modify the inherent functional specializations of visual cortical areas and dynamically reweight their contributions to perceptual decisions based on their representational qualities. These neural changes might serve as the neural substrate for the transfer of perceptual learning.

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Kelly, K., K. DeSimone, K. Schneider et J. Steeves. « Cortical thickening of early visual areas in early monocular enucleation ». Journal of Vision 11, n^o 11 (23 septembre 2011) : 403. http://dx.doi.org/10.1167/11.11.403.

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Pigarev, I. N., V. A. Bagaev, E. V. Levichkina, G. O. Fedorov et I. I. Busigina. « Cortical visual areas process intestinal information during slow-wave sleep ». Neurogastroenterology & ; Motility 25, n^o 3 (6 décembre 2012) : 268—e169. http://dx.doi.org/10.1111/nmo.12052.

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Reppas, John B., Sourabh Niyogi, Anders M. Dale, Martin I. Sereno et Roger B. H. Tootell. « Representation of motion boundaries in retinotopic human visual cortical areas ». Nature 388, n^o 6638 (juillet 1997) : 175–79. http://dx.doi.org/10.1038/40633.

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Fang, Fang, Nihong Chen, Peng Cai, Tiangang Zhou et Benjamin Thompson. « Perceptual learning modifies the functional specializations of visual cortical areas ». Journal of Vision 16, n^o 12 (1 septembre 2016) : 1091. http://dx.doi.org/10.1167/16.12.1091.

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Baldauf, Zsolt B. « SMI-32 parcellates the visual cortical areas of the marmoset ». Neuroscience Letters 383, n^o 1-2 (juillet 2005) : 109–14. http://dx.doi.org/10.1016/j.neulet.2005.03.055.

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Ohkubo, Tatsunobu, Tetsuya Matsuda, Hiromi Ohkubo, Hidekazu Serizawa, Eisuke Matsushima, Masato Matsuura, Kentaro Inoue, Masato Taira, Hideo Sakata et Takuya Kojima. « An fMRI analysis of cortical areas related to visual retention ». NeuroImage 13, n^o 6 (juin 2001) : 715. http://dx.doi.org/10.1016/s1053-8119(01)92058-0.

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Ahlfors, S. P., A. M. Dale, J. W. Belliveau, R. J. Ilmoniemi, M. Huotilainen, A. Korvenoja, J. Virtanen et al. « Spatiotemporal imaging of human cortical areas selective to visual motion ». NeuroImage 3, n^o 3 (juin 1996) : S262. http://dx.doi.org/10.1016/s1053-8119(96)80264-3.

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Juavinett, Ashley L., et Edward M. Callaway. « Pattern and Component Motion Responses in Mouse Visual Cortical Areas ». Current Biology 25, n^o 13 (juin 2015) : 1759–64. http://dx.doi.org/10.1016/j.cub.2015.05.028.

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Sharifian, Fariba, Lauri Nurminen et Simo Vanni. « Visual Interactions Conform to Pattern Decorrelation in Multiple Cortical Areas ». PLoS ONE 8, n^o 7 (10 juillet 2013) : e68046. http://dx.doi.org/10.1371/journal.pone.0068046.

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Park, S. H., K. Cha et S. H. Lee. « Coaxial Anisotropy of Cortical Point Spread in Human Visual Areas ». Journal of Neuroscience 33, n^o 3 (16 janvier 2013) : 1143–56. http://dx.doi.org/10.1523/jneurosci.2404-12.2013.

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Ushida, Takahiro, Tatsunori Ikemoto, Shinichirou Taniguchi, Olga Zinchuk, Akio Ushida, Shigeki Tanaka, Wasa Ueda et Toshikazu Tani. « Activation of distinct cortical areas elicited by visual emotional experiences ». International Congress Series 1278 (mars 2005) : 197–200. http://dx.doi.org/10.1016/j.ics.2004.11.072.

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Articles de revues sur le sujet « Visual cortical areas »

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