Mapping Short Association Fibers in the Early Cortical Visual Processing Stream Using In Vivo Diffusion Tractography

Abstract Short association fibers (U-fibers) connect proximal cortical areas and constitute the majority of white matter connections in the human brain. U-fibers play an important role in brain development, function, and pathology but are underrepresented in current descriptions of the human brain connectome, primarily due to methodological challenges in diffusion magnetic resonance imaging (dMRI) of these fibers. High spatial resolution and dedicated fiber and tractography models are required to reliably map the U-fibers. Moreover, limited quantitative knowledge of their geometry and distribution makes validation of U-fiber tractography challenging. Submillimeter resolution diffusion MRI—facilitated by a cutting-edge MRI scanner with 300 mT/m maximum gradient amplitude—was used to map U-fiber connectivity between primary and secondary visual cortical areas (V1 and V2, respectively) in vivo. V1 and V2 retinotopic maps were obtained using functional MRI at 7T. The mapped V1–V2 connectivity was retinotopically organized, demonstrating higher connectivity for retinotopically corresponding areas in V1 and V2 as expected. The results were highly reproducible, as demonstrated by repeated measurements in the same participants and by an independent replication group study. This study demonstrates a robust U-fiber connectivity mapping in vivo and is an important step toward construction of a more complete human brain connectome.

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Diffusion MRI microstructure models with in vivo human brain Connectome data: results from a multi-group comparison

NMR in Biomedicine ◽

10.1002/nbm.3734 ◽

2017 ◽

Vol 30 (9) ◽

pp. e3734 ◽

Cited By ~ 14

Author(s):

Uran Ferizi ◽

Benoit Scherrer ◽

Torben Schneider ◽

Mohammad Alipoor ◽

Odin Eufracio ◽

...

Keyword(s):

Human Brain ◽

Diffusion Mri ◽

Group Comparison ◽

Brain Connectome

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Euclidean distance as a measure to distinguish ventral and dorsal white matter connectivity in the human brain

10.1101/053959 ◽

2016 ◽

Author(s):

Philipp Kellmeyer ◽

Magnus-Sebastian Vry

Keyword(s):

White Matter ◽

Human Brain ◽

Cognitive Processing ◽

Euclidean Distance ◽

Large Scale ◽

Diffusion Tensor ◽

Large Body ◽

Coordinate Space ◽

Fiber Tractography

AbstractFiber tractography based on diffusion tensor imaging (DTI) has become an important research tool for investigating the anatomical connectivity between brain regions in vivo. Combining DTI with functional magnetic resonance imaging (fMRI) allows for the mapping of structural and functional architecture of large-scale networks for cognitive processing. This line of research has shown that ventral and dorsal fiber pathways subserve different aspects of bottom-up- and top-down processing in the human brain.Here, we investigate the feasibility and applicability of Euclidean distance as a simple geometric measure to differentiate ventral and dorsal long-range white matter fiber pathways tween parietal and inferior frontal cortical regions, employing a body of studies that used probabilistic tractography.We show that ventral pathways between parietal and inferior frontal cortex have on average a significantly longer Euclidean distance in 3D-coordinate space than dorsal pathways. We argue that Euclidean distance could provide a simple measure and potentially a boundary value to assess patterns of connectivity in fMRI studies. This would allow for a much broader assessment of general patterns of ventral and dorsal large-scale fiber connectivity for different cognitive operations in the large body of existing fMRI studies lacking additional DTI data.

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Visual Interhemispheric and Striate-Extrastriate Cortical Connections in the Rabbit: A Multiple Tracer Study

Neurology Research International ◽

10.1155/2015/591245 ◽

2015 ◽

Vol 2015 ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

Adrian K. Andelin ◽

David J. Bruning ◽

Daniel J. Felleman ◽

Jaime F. Olavarria

Keyword(s):

Visual Processing ◽

Alternative Model ◽

Tracer Study ◽

Cortical Areas ◽

Callosal Connections ◽

Cortical Connections ◽

Visual Areas ◽

Cortical Visual Processing ◽

Rats And Mice ◽

Extrastriate Areas

Previous studies in rabbits identified an array of extrastriate cortical areas anatomically connected with V1 but did not describe their internal topography. To address this issue, we injected multiple anatomical tracers into different regions in V1 of the same animal and analyzed the topography of resulting extrastriate labeled fields with reference to the patterns of callosal connections and myeloarchitecture revealed in tangential sections of the flattened cortex. Our results extend previous studies and provide further evidence that rabbit extrastriate areas resemble the visual areas in rats and mice not only in their general location with respect to V1 but also in their internal topography. Moreover, extrastriate areas in the rabbit maintain a constant relationship with myeloarchitectonic borders and features of the callosal pattern. These findings highlight the rabbit as an alternative model to rats and mice for advancing our understanding of cortical visual processing in mammals, especially for projects benefiting from a larger brain.

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In vivo Exploration of the Connectivity between the Subthalamic Nucleus and the Globus Pallidus in the Human Brain Using Multi-Fiber Tractography

Frontiers in Neuroanatomy ◽

10.3389/fnana.2016.00119 ◽

2017 ◽

Vol 10 ◽

Cited By ~ 7

Author(s):

Sonia Pujol ◽

Ryan Cabeen ◽

Sophie B. Sébille ◽

Jérôme Yelnik ◽

Chantal François ◽

...

Keyword(s):

Human Brain ◽

Globus Pallidus ◽

Subthalamic Nucleus ◽

Fiber Tractography

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Adolescence is associated with genomically patterned consolidation of the hubs of the human brain connectome

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1601745113 ◽

2016 ◽

Vol 113 (32) ◽

pp. 9105-9110 ◽

Cited By ~ 191

Author(s):

Kirstie J. Whitaker ◽

Petra E. Vértes ◽

Rafael Romero-Garcia ◽

František Váša ◽

Michael Moutoussis ◽

...

Keyword(s):

Human Brain ◽

Brain Maturation ◽

Association Cortex ◽

Projection Neurons ◽

Consolidation Process ◽

Developmental Variation ◽

Cortical Areas ◽

Brain Connectome ◽

Age Related ◽

High Incidence

How does human brain structure mature during adolescence? We used MRI to measure cortical thickness and intracortical myelination in 297 population volunteers aged 14–24 y old. We found and replicated that association cortical areas were thicker and less myelinated than primary cortical areas at 14 y. However, association cortex had faster rates of shrinkage and myelination over the course of adolescence. Age-related increases in cortical myelination were maximized approximately at the internal layer of projection neurons. Adolescent cortical myelination and shrinkage were coupled and specifically associated with a dorsoventrally patterned gene expression profile enriched for synaptic, oligodendroglial- and schizophrenia-related genes. Topologically efficient and biologically expensive hubs of the brain anatomical network had greater rates of shrinkage/myelination and were associated with overexpression of the same transcriptional profile as cortical consolidation. We conclude that normative human brain maturation involves a genetically patterned process of consolidating anatomical network hubs. We argue that developmental variation of this consolidation process may be relevant both to normal cognitive and behavioral changes and the high incidence of schizophrenia during human brain adolescence.

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In vivo 3D Reconstruction of the Human Pallidothalamic and Nigrothalamic Pathways With Super-Resolution 7T MR Track Density Imaging and Fiber Tractography

Frontiers in Neuroanatomy ◽

10.3389/fnana.2021.739576 ◽

2021 ◽

Vol 15 ◽

Author(s):

Dae-Hyuk Kwon ◽

Sun Ha Paek ◽

Young-Bo Kim ◽

Haigun Lee ◽

Zang-Hee Cho

Keyword(s):

Basal Ganglia ◽

3D Reconstruction ◽

Human Brain ◽

Super Resolution ◽

Track Density ◽

7 Tesla ◽

Fiber Tractography ◽

Resolution Limit ◽

Magnetic Resonance Imaging Mri

The output network of the basal ganglia plays an important role in motor, associative, and limbic processing and is generally characterized by the pallidothalamic and nigrothalamic pathways. However, these connections in the human brain remain difficult to elucidate because of the resolution limit of current neuroimaging techniques. The present study aimed to investigate the mesoscopic nature of these connections between the thalamus, substantia nigra pars reticulata, and globus pallidus internal segment using 7 Tesla (7T) magnetic resonance imaging (MRI). In this study, track-density imaging (TDI) of the whole human brain was employed to overcome the limitations of observing the pallidothalamic and nigrothalamic tracts. Owing to the super-resolution of the TD images, the substructures of the SN, as well as the associated tracts, were identified. This study demonstrates that 7T MRI and MR tractography can be used to visualize anatomical details, as well as 3D reconstruction, of the output projections of the basal ganglia.

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Microstructural organizational patterns in the human corticostriatal system

Journal of Neurophysiology ◽

10.1152/jn.00995.2011 ◽

2012 ◽

Vol 107 (11) ◽

pp. 2984-2995 ◽

Cited By ~ 58

Author(s):

Timothy D. Verstynen ◽

David Badre ◽

Kevin Jarbo ◽

Walter Schneider

Keyword(s):

Basal Ganglia ◽

Computational Models ◽

Ex Vivo ◽

Local Level ◽

Fiber Tractography ◽

Asymmetry Of Information ◽

Cortical Areas ◽

Posterior Direction ◽

Organizational Patterns

The axons that project into the striatum are known to segregate according to macroscopic cortical systems; however, the within-region organization of these fibers has yet to be described in humans. We used in vivo fiber tractography, in neurologically healthy adults, to map white matter bundles that originate in different neocortical areas, navigate complex fiber crossings, and project into the striatum. As expected, these fibers were generally segregated according to cortical origin. Within a subset of pathways, a patched pattern of inputs was observed, consistent with previous ex vivo histological studies. In projections from the prefrontal cortex, we detected a topography in which fibers from rostral prefrontal areas projected mostly to rostral parts of the striatum and vice versa for inputs originating in caudal cortical areas. Importantly, within this prefrontal system there was also an asymmetry in the subset of divergent projections, with more fibers projecting in a posterior direction than anterior. This asymmetry of information projecting into the basal ganglia was predicted by previous network-level computational models. A rostral-caudal topography was also present at the local level in otherwise somatotopically organized fibers projecting from the motor cortex. This provides clear evidence that the longitudinal organization of input fields, observed at the macroscopic level across cortical systems, is also found at the microstructural scale at which information is segregated as it enters the human basal ganglia.

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Distinct recruitment of feed-forward and recurrent pathways across higher-order areas of mouse visual cortex

10.1101/2020.09.24.312140 ◽

2020 ◽

Author(s):

Jennifer Y. Li ◽

Charles A. Hass ◽

Ian Matthews ◽

Amy C. Kristl ◽

Lindsey L. Glickfeld

Keyword(s):

Visual Processing ◽

Higher Order ◽

Feed Forward ◽

Cortical Areas ◽

Physiological Properties ◽

Cortical Visual Processing ◽

Visual Cortical ◽

Mouse Visual Cortex ◽

Whole Cell Recordings

AbstractCortical visual processing transforms features of the external world into increasingly complex and specialized neuronal representations. These transformations arise in part through target-specific routing of information; however, within-area computations may also contribute to area-specific function. Here, we sought to determine whether higher-order visual cortical areas LM, AL, PM, and AM have specialized anatomical and physiological properties by using a combination of whole-cell recordings and optogenetic stimulation of V1 axons in vitro. We discovered area-specific differences in the strength of recruitment of interneurons through feed-forward and recurrent pathways, as well as differences in cell-intrinsic properties and interneuron densities. These differences were most striking when comparing across medial and lateral areas, suggesting that these areas have distinct profiles for net excitability and integration of V1 inputs. Thus, cortical areas are not defined simply by the information they receive, but also by area-specific circuit properties that enable specialized filtering of these inputs.

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