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9 results on '"Nikola, T."'

1. Unique Features of Subcortical Circuits in a Macaque Model of Congenital Blindness

Author

Henry Kennedy, Kenneth Knoblauch, Nikola T. Markov, Loïc Magrou, Pascal Barone, Michel Berland, Gwylan Scheeren, Pascale Giroud, Colette Dehay, Herbert P. Killackey, Institut cellule souche et cerveau (U846 Inserm - UCBL1), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre de recherche cerveau et cognition (CERCO), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut des sciences du cerveau de Toulouse. (ISCT), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Cerveau et vision, Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-IFR19-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut des sciences du cerveau de Toulouse. (ISCT), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Princeton University, University of Amsterdam [Amsterdam] (UvA), University of California [Irvine] (UC Irvine), University of California (UC), BARONE, Pascal, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), University of California [Irvine] (UCI), University of California, and Institut cellule souche et cerveau / Stem Cell and Brain Research Institute (SBRI)

Subjects
Male, Cognitive Neuroscience, [SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology, Thalamus, pulvinar, deafferentation, Visual system, Lateral geniculate nucleus, Blindness, primate, Macaque, 03 medical and health sciences, Cellular and Molecular Neuroscience, 0302 clinical medicine, Extrastriate cortex, biology.animal, Cortex (anatomy), medicine, Animals, Primate, Visual Pathways, hybrid cortex, ComputingMilieux_MISCELLANEOUS, 030304 developmental biology, Visual Cortex, Neurons, 0303 health sciences, Brain Mapping, Anophthalmia, biology, [SCCO.NEUR]Cognitive science/Neuroscience, [SCCO.NEUR] Cognitive science/Neuroscience, [SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology, Geniculate Bodies, medicine.disease, Macaca fascicularis, medicine.anatomical_structure, connectivity, Female, Neuroscience, 030217 neurology & neurosurgery
Abstract

There is an extensive modification of the functional organization of the brain in the congenital blind human, although there is little understanding of the structural underpinnings of these changes. The visual system of macaque has been extensively characterized both anatomically and functionally. We have taken advantage of this to examine the influence of congenital blindness in a macaque model of developmental anophthalmia. Developmental anophthalmia in macaque effectively removes the normal influence of the thalamus on cortical development leading to an induced “hybrid cortex (HC)” combining features of primary visual and extrastriate cortex. Here we show that retrograde tracers injected in early visual areas, including HC, reveal a drastic reduction of cortical projections of the reduced lateral geniculate nucleus. In addition, there is an important expansion of projections from the pulvinar complex to the HC, compared to the controls. These findings show that the functional consequences of congenital blindness need to be considered in terms of both modifications of the interareal cortical network and the ascending visual pathways.

Published
2019

2. Unique Features of Sub-Cortical Circuits in A Macaque Model of Congenital Blindness

Author

Kenneth Knoblauch, Herbert P. Killackey, Loïc Magrou, Pascale Barone, Gwylan Scheeren, Michel Berland, Colette Dehay, Nikola T. Markov, Henry Kennedy, and Pascale Giroud

Subjects
0303 health sciences, Retina, Anophthalmia, Thalamus, Visual system, Biology, medicine.disease, Lateral geniculate nucleus, Macaque, 03 medical and health sciences, 0302 clinical medicine, medicine.anatomical_structure, Extrastriate cortex, Cortex (anatomy), biology.animal, medicine, Neuroscience, 030217 neurology & neurosurgery, 030304 developmental biology
Abstract

There is extensive modification of the functional organization of the brain in the congenital blind human, although there is little understanding of the structural underpinnings of these changes. The visual system of macaque has been extensively characterized both anatomically and functionally. We have taken advantage of this to examine the influence of the congenital blindness in macaque resulting from the removal of the retina during in utero development. Developmental anophthalmia in macaque effectively removes the normal influence of the thalamus on cortical development leading to an induced hybrid cortex (HC) combining features of primary visual and extrastriate cortex. Here we show that retrograde tracers injected in early visual areas including hybrid cortex reveals a drastic reduction of cortical projections of the reduced lateral geniculate nucleus. In addition, there is an important expansion of projections from the pulvinar complex to the hybrid cortex, compared to the controls. These findings show that the functional consequences of congenital blindness need to be considered in terms of both modifications of the inter-areal cortical network and the ascending visual pathways.

Published
2019

3. The Tribal Networks of the Cerebral Cortex

Author

Nikola T., Markov, author, Maria-Magdolina, Ercsey-Ravasz, author, Marie-Alice, Gariel, author, Colette, Dehay, author, Kenneth, Knoblauch, author, Zoltan, Toroczkai, author, and Henry, Kennedy, author

Published
2011
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4. Anatomy of hierarchy: Feedforward and feedback pathways in macaque visual cortex

Author

Shimon Ullman, Nikola T. Markov, Kenneth Knoblauch, Pascal Chameau, Cyril Huissoud, Henry Kennedy, Pierre Misery, Pascal Barone, Pascale Giroud, René Quilodran, Colette Dehay, Camille Lamy, Arnaud Falchier, Julien Vezoli, Institut cellule souche et cerveau (U846 Inserm - UCBL1), Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM), Swammerdam Institute for Life Sciences, Section Neurobiology, Oficina de Educación Médica, Facultad de Medicina Universidad de Valparaiso, Weizmann Institute of Science [Rehovot, Israël], Centre de recherche cerveau et cognition (CERCO), Institut des sciences du cerveau de Toulouse. (ISCT), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Cellular and Computational Neuroscience (SILS, FNWI)

Subjects
Male, Visual system, Cell morphology, Macaque, Feedback, Sensory, biology.animal, Cortex (anatomy), neocortex, medicine, Animals, Visual Pathways, Research Articles, ComputingMilieux_MISCELLANEOUS, Visual Cortex, Neurons, cell morphology, Neocortex, biology, [SCCO.NEUR]Cognitive science/Neuroscience, General Neuroscience, Neuroanatomical Tract-Tracing Techniques, Anatomy, Macaca mulatta, Retrograde tracing, Macaca fascicularis, medicine.anatomical_structure, Visual cortex, Female, monkey, retrograde tracing, Neuroscience
Abstract

The laminar location of the cell bodies and terminals of interareal connections determines the hierarchical structural organization of the cortex and has been intensively studied. However, we still have only a rudimentary understanding of the connectional principles of feedforward (FF) and feedback (FB) pathways. Quantitative analysis of retrograde tracers was used to extend the notion that the laminar distribution of neurons interconnecting visual areas provides an index of hierarchical distance (percentage of supragranular labeled neurons [SLN]). We show that: 1) SLN values constrain models of cortical hierarchy, revealing previously unsuspected areal relations; 2) SLN reflects the operation of a combinatorial distance rule acting differentially on sets of connections between areas; 3) Supragranular layers contain highly segregated bottom-up and top-down streams, both of which exhibit point-to-point connectivity. This contrasts with the infragranular layers, which contain diffuse bottom-up and top-down streams; 4) Cell filling of the parent neurons of FF and FB pathways provides further evidence of compartmentalization; 5) FF pathways have higher weights, cross fewer hierarchical levels, and are less numerous than FB pathways. Taken together, the present results suggest that cortical hierarchies are built from supra- and infragranular counterstreams. This compartmentalized dual counterstream organization allows point-to-point connectivity in both bottom-up and top-down directions.

Published
2013

5. A Predictive Network Model of Cerebral Cortical Connectivity Based on a Distance Rule

Author

David C. Van Essen, Kenneth Knoblauch, Camille Lamy, Mária Ercsey-Ravasz, Zoltán Toroczkai, Nikola T. Markov, and Henry Kennedy

Subjects
Computer science, Neuroscience(all), Models, Neurological, Binary number, Topology, Brain mapping, Article, 03 medical and health sciences, 0302 clinical medicine, Animals, Humans, Exponential decay, 030304 developmental biology, Network model, Cerebral Cortex, Random graph, Brain Mapping, 0303 health sciences, Quantitative Biology::Neurons and Cognition, General Neuroscience, Log-normal distribution, Macaca, Graph (abstract data type), Minification, Nerve Net, Neuroscience, 030217 neurology & neurosurgery
Abstract

SummaryRecent advances in neuroscience have engendered interest in large-scale brain networks. Using a consistent database of cortico-cortical connectivity, generated from hemisphere-wide, retrograde tracing experiments in the macaque, we analyzed interareal weights and distances to reveal an important organizational principle of brain connectivity. Using appropriate graph theoretical measures, we show that although very dense (66%), the interareal network has strong structural specificity. Connection weights exhibit a heavy-tailed lognormal distribution spanning five orders of magnitude and conform to a distance rule reflecting exponential decay with interareal separation. A single-parameter random graph model based on this rule predicts numerous features of the cortical network: (1) the existence of a network core and the distribution of cliques, (2) global and local binary properties, (3) global and local weight-based communication efficiencies modeled as network conductance, and (4) overall wire-length minimization. These findings underscore the importance of distance and weight-based heterogeneity in cortical architecture and processing.

Published
2013

6. The importance of being hierarchical

Author

Henry Kennedy and Nikola T. Markov

Subjects
Neurons, Hierarchy (mathematics), Computer science, General Neuroscience, Compartment (ship), media_common.quotation_subject, Models, Neurological, Feed forward, medicine.anatomical_structure, Cortex (anatomy), Perception, medicine, Animals, Humans, Nerve Net, Visual Fields, Neuroscience, Generative grammar, Visual Cortex, Network analysis, media_common
Abstract

Our understanding of cortical electrophysiology and anatomy at the single-cell level has led to the present day insight in to the function of connections linking cortical areas. This made it possible to elaborate the cortical hierarchy in the early 1990s and was a prerequisite for the development of present day generative models of perception. These computational hierarchical models make strong predictions concerning the roles of feedforward (FF) and feedback (FB) pathways, including their segregation and topographical precision in both directions. This shows that instead of a single stream in the upper and lower compartments of the cortex there is in fact a bi-directional counter-stream in each compartment of the cortex. A significant advance in this field will require more detailed anatomy hand in hand with a network analysis of the directed and weighted cortical matrix.

Published
2013

7. A weighted and directed interareal connectivity matrix for macaque cerebral cortex

Author

L. Magrou, Kenneth Knoblauch, Marie-Alice Gariel, Arnaud Falchier, D. C. Van Essen, Zoltán Toroczkai, Julien Vezoli, P. Misery, C. Huissoud, Camille Lamy, Dominique Sappey-Marinier, Jerome Sallet, Simon Clavagnier, Colette Dehay, Henry Kennedy, Nikola T. Markov, Pascal Barone, René Quilodran, A. R. Ribeiro Gomes, Pascale Giroud, Mária Ercsey-Ravasz, R. Gamanut, Institut cellule souche et cerveau (U846 Inserm - UCBL1), Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre d'Etude et de Recherche Multimodal Et Pluridisciplinaire en imagerie du vivant (CERMEP - imagerie du vivant), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-CHU Grenoble-Hospices Civils de Lyon (HCL)-CHU Saint-Etienne-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), RMN et optique : De la mesure au biomarqueur, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)

Subjects
[SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, Cognitive Neuroscience, Models, Neurological, Neuroimaging, Macaque, Brain mapping, Standard deviation, Cellular and Molecular Neuroscience, Matrix (mathematics), Dominating set, biology.animal, Cortex (anatomy), Neural Pathways, Image Processing, Computer-Assisted, medicine, Animals, Neuronal Tract-Tracers, ComputingMilieux_MISCELLANEOUS, Cerebral Cortex, Brain Mapping, biology, connection, Articles, graph, Macaca mulatta, Macaca fascicularis, Diffusion Magnetic Resonance Imaging, cortex, medicine.anatomical_structure, Cerebral cortex, network, Log-normal distribution, monkey, Psychology, Neuroscience
Abstract

Retrograde tracer injections in 29 of the 91 areas of the macaque cerebral cortex revealed 1,615 interareal pathways, a third of which have not previously been reported. A weight index (extrinsic fraction of labeled neurons [FLNe]) was determined for each area-to-area pathway. Newly found projections were weaker on average compared with the known projections; nevertheless, the 2 sets of pathways had extensively overlapping weight distributions. Repeat injections across individuals revealed modest FLNe variability given the range of FLNe values (standard deviation

Published
2014

8. The role of long-range connections on the specificity of the macaque interareal cortical network

Author

Pascale Giroud, Kenneth Knoblauch, Mária Ercsey-Ravasz, Nikola T. Markov, Loïc Magrou, Zoltán Toroczkai, Henry Kennedy, Pierre Misery, Ana Rita Ribeiro Gomes, David C. Van Essen, Camille Lamy, Colette Dehay, Pascal Barone, Institut cellule souche et cerveau (U846 Inserm - UCBL1), Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM), Department of Physics, University of Notre Dame [Indiana] (UND), Centre de recherche cerveau et cognition (CERCO), Institut des sciences du cerveau de Toulouse. (ISCT), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Anatomy & Neurobiology, and University of Washington [Seattle]

Subjects
anatomy, Databases, Factual, Nerve net, Macaque, Brain mapping, 03 medical and health sciences, 0302 clinical medicine, Similarity (network science), biology.animal, medicine, Range (statistics), neocortex, Animals, 030304 developmental biology, Cerebral Cortex, Brain Mapping, 0303 health sciences, Multidisciplinary, Neocortex, biology, Biological Sciences, medicine.anatomical_structure, Geography, Cortical network, Macaca, Graph (abstract data type), [SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], Nerve Net, monkey, Neuroscience, 030217 neurology & neurosurgery
Abstract

We investigated the influence of interareal distance on connectivity patterns in a database obtained from the injection of retrograde tracers in 29 areas distributed over six regions (occipital, temporal, parietal, frontal, prefrontal, and limbic). One-third of the 1,615 pathways projecting to the 29 target areas were reported only recently and deemed new-found projections (NFPs). NFPs are predominantly long-range, low-weight connections. A minimum dominating set analysis (a graph theoretic measure) shows that NFPs play a major role in globalizing input to small groups of areas. Randomization tests show that ( i ) NFPs make important contributions to the specificity of the connectivity profile of individual cortical areas, and ( ii ) NFPs share key properties with known connections at the same distance. We developed a similarity index, which shows that intraregion similarity is high, whereas the interregion similarity declines with distance. For area pairs, there is a steep decline with distance in the similarity and probability of being connected. Nevertheless, the present findings reveal an unexpected binary specificity despite the high density (66%) of the cortical graph. This specificity is made possible because connections are largely concentrated over short distances. These findings emphasize the importance of long-distance connections in the connectivity profile of an area. We demonstrate that long-distance connections are particularly prevalent for prefrontal areas, where they may play a prominent role in large-scale communication and information integration.

Published
2013

9. Strong loops and weak links in the neocortex

Author

Rodney J. Douglas, K. Knoblauch, Henry Kennedy, Julien Vezoli, Marie-Alice Gariel, and Nikola T. Markov

Subjects
Physics, Neocortex, medicine.anatomical_structure, General Neuroscience, medicine, General Medicine, Neuroscience
Published
2009

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