scholarly journals Exploring the laminar connectome

2021 ◽  
Author(s):  
Ittai Shamir ◽  
Omri Tomer ◽  
Ronnie Krupnik ◽  
Yaniv Assaf
Keyword(s):  
White Matter ◽  
Grey Matter ◽  
Structural Description ◽  
Mri Imaging ◽  
Healthy Human ◽  
Cortical Grey Matter ◽  
Cortical Laminar ◽  
White Matter Connectivity ◽  
Human Brains

The human connectome is the complete structural description of the network of connections and elements that form the wiring diagram of the brain. Because of the current scarcity of information regarding laminar end points of white matter tracts inside cortical grey matter, tractography remains focused on cortical partitioning into regions, while ignoring radial partitioning into laminar components. To overcome this biased representation of the cortex as a single homogenous unit, we use a recent data-derived model of cortical laminar connectivity, which has been further explored and corroborated in the macaque brain by comparison to published studies. The model integrates multimodal MRI imaging datasets regarding both white matter connectivity and grey matter laminar composition into a laminar-level connectome. In this study we model the laminar connectome of healthy human brains (N=20) and explore them via a set of neurobiologically meaningful complex network measures. Our analysis demonstrates a subdivision of network hubs that appear in the standard connectome into each individual component of the laminar connectome, giving a fresh look into the role of laminar components in cortical connectivity and offering new prospects in the fields of both structural and functional connectivity.

scholarly journals A higher proportion of ermin-immunopositive oligodendrocytes in areas of remyelination

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256155
Author(s):  
Intakhar Ahmad ◽  
Stig Wergeland ◽  
Eystein Oveland ◽  
Lars Bø
Keyword(s):  
Multiple Sclerosis ◽  
White Matter ◽  
Corpus Callosum ◽  
Mouse Model ◽  
Grey Matter ◽  
Early Stage ◽  
Relative Proportion ◽  
Normal Appearing White Matter ◽  
The Brain

Incomplete remyelination is frequent in multiple sclerosis (MS)-lesions, but there is no established marker for recent remyelination. We investigated the role of the oligodendrocyte/myelin protein ermin in de- and remyelination in the cuprizone (CPZ) mouse model, and in MS. The density of ermin+ oligodendrocytes in the brain was significantly decreased after one week of CPZ exposure (p < 0.02). The relative proportion of ermin+ cells compared to cells positive for the late-stage oligodendrocyte marker Nogo-A increased at the onset of remyelination in the corpus callosum (p < 0.02). The density of ermin-positive cells increased in the corpus callosum during the CPZ-phase of extensive remyelination (p < 0.0001). In MS, the density of ermin+ cells was higher in remyelinated lesion areas compared to non-remyelinated areas both in white- (p < 0.0001) and grey matter (p < 0.0001) and compared to normal-appearing white matter (p < 0.001). Ermin immunopositive cells in MS-lesions were not immunopositive for the early-stage oligodendrocyte markers O4 and O1, but a subpopulation was immunopositive for Nogo-A. The data suggest a relatively higher proportion of ermin immunopositivity in oligodendrocytes compared to Nogo-A indicates recent or ongoing remyelination.

Regional brain volumes, microstructure and neurodevelopment in moderate–late preterm children

2020 ◽  
Vol 105 (6) ◽  
pp. 593-599 ◽  
Author(s):  
Claire E Kelly ◽  
Deanne K Thompson ◽  
Alicia J Spittle ◽  
Jian Chen ◽  
Marc L Seal ◽  
...  
Keyword(s):  
White Matter ◽  
Grey Matter ◽  
Diffusion Tensor ◽  
Brain Mri ◽  
Developmental Outcomes ◽  
Late Preterm ◽  
Brain Volumes ◽  
Regional Brain ◽  
White Matter Microstructure ◽  
Cortical Grey Matter

ObjectiveTo explore whether regional brain volume and white matter microstructure at term-equivalent age (TEA) are associated with development at 2 years of age in children born moderate–late preterm (MLPT).Study designA cohort of MLPT infants had brain MRI at approximately TEA (38–44 weeks’ postmenstrual age) and had a developmental assessment (Bayley Scales of Infant and Toddler Development and Infant Toddler Social Emotional Assessment) at 2 years’ corrected age. Relationships between cortical grey matter and white matter volumes and 2-year developmental outcomes were explored using voxel-based morphometry. Relationships between diffusion tensor measures of white matter microstructure (fractional anisotropy (FA) and axial (AD), radial (RD) and mean (MD) diffusivities) and 2-year developmental outcomes were explored using tract-based spatial statistics.Results189 MLPT children had data from at least one MRI modality (volumetric or diffusion) and data for at least one developmental domain. Larger cortical grey and white matter volumes in many brain regions, and higher FA and lower AD, RD and MD in several major white matter regions, were associated with better cognitive and language scores. There was little evidence that cortical grey matter and white matter volumes and white matter microstructure were associated with motor and behavioural outcomes.ConclusionsRegional cortical grey matter and white matter volumes and white matter microstructure are associated with cognitive and language development at 2 years of age in MLPT children. Thus, early alterations to brain volumes and microstructure may contribute to some of the developmental deficits described in MLPT children.

Concordance of Parent-Offspring Cortico-Basal Ganglia White Matter Connectivity: The Role of Parental Depression and Parent-Child Bonding

2020 ◽  
Vol 87 (9) ◽  
pp. S264
Author(s):  
Eyal Abraham ◽  
Myrna Weissman ◽  
Priya Wickramaratne ◽  
Milenna van Dijk ◽  
Lifang Pan ◽  
...  
Keyword(s):  
White Matter ◽  
Basal Ganglia ◽  
Parental Depression ◽  
White Matter Connectivity ◽  
Parent Child

Linking white matter tracts to associated cortical grey matter: A tract extension methodology

NeuroImage ◽  
2012 ◽  
Vol 59 (4) ◽  
pp. 3094-3102 ◽  
Author(s):  
D.J. Tozer ◽  
D.T. Chard ◽  
B. Bodini ◽  
O. Ciccarelli ◽  
D.H. Miller ◽  
...  
Keyword(s):  
White Matter ◽  
Grey Matter ◽  
White Matter Tracts ◽  
Cortical Grey Matter

Grey matter abnormality in progressive multifocal leucoencephalopathy

2021 ◽  
pp. practneurol-2020-002852
Author(s):  
Christopher Yuki Itoh ◽  
Han Sung Lee ◽  
Alan Howe Yee
Keyword(s):  
White Matter ◽  
Gold Standard ◽  
Grey Matter ◽  
Jc Virus ◽  
White Matter Disease ◽  
Viral Dna ◽  
Progressive Multifocal Leucoencephalopathy ◽  
Cerebral Grey Matter ◽  
Cortical Grey Matter

Progressive multifocal leucoencephalopathy (PML) is a demyelinating white matter disease that most often affects immunocompromised people infected by JC virus. The diagnostic gold standard is demonstrable viral DNA or protein from histopathological tissue. However, there are few detailed descriptions of cortical grey matter involvement on neuroimaging. Here we describe the histopathological correlate of cerebral grey matter involvement and radiological accompaniment in a patient with biopsy proven PML.

scholarly journals Exploring the role of white matter connectivity in cortex maturation

PLoS ONE ◽  
2017 ◽  
Vol 12 (5) ◽  
pp. e0177466 ◽  
Author(s):  
Cecilia L. Friedrichs-Maeder ◽  
Alessandra Griffa ◽  
Juliane Schneider ◽  
Petra Susan Hüppi ◽  
Anita Truttmann ◽  
...  
Keyword(s):  
White Matter ◽  
White Matter Connectivity

scholarly journals Oxygen challenge magnetic resonance imaging in healthy human volunteers

2016 ◽  
Vol 37 (1) ◽  
pp. 366-376 ◽  
Author(s):  
Krishna A Dani ◽  
Fiona C Moreton ◽  
Celestine Santosh ◽  
Rosario Lopez ◽  
David Brennan ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
White Matter ◽  
Magnetic Resonance ◽  
Grey Matter ◽  
Statistical Significance ◽  
Resonance Imaging ◽  
Two Stage ◽  
Healthy Human

Oxygen challenge imaging involves transient hyperoxia applied during deoxyhaemoglobin sensitive (T2*-weighted) magnetic resonance imaging and has the potential to detect changes in brain oxygen extraction. In order to develop optimal practical protocols for oxygen challenge imaging, we investigated the influence of oxygen concentration, cerebral blood flow change, pattern of oxygen administration and field strength on T2*-weighted signal. Eight healthy volunteers underwent multi-parametric magnetic resonance imaging including oxygen challenge imaging and arterial spin labelling using two oxygen concentrations (target FiO2 of 100 and 60%) administered consecutively (two-stage challenge) at both 1.5T and 3T. There was a greater signal increase in grey matter compared to white matter during oxygen challenge (p < 0.002 at 3T, P < 0.0001 at 1.5T) and at FiO2 = 100% compared to FiO2 = 60% in grey matter at both field strengths (p < 0.02) and in white matter at 3T only (p = 0.0314). Differences in the magnitude of signal change between 1.5T and 3T did not reach statistical significance. Reduction of T2*-weighted signal to below baseline, after hyperoxia withdrawal, confounded interpretation of two-stage oxygen challenge imaging. Reductions in cerebral blood flow did not obscure the T2*-weighted signal increases. In conclusion, the optimal protocol for further study should utilise target FiO2 = 100% during a single oxygen challenge. Imaging at both 1.5T and 3T is clinically feasible.

scholarly journals An MRI-based, data-driven model of cortical laminar connectivity

2020 ◽  
Author(s):  
Ittai Shamir ◽  
Yaniv Assaf
Keyword(s):  
Grey Matter ◽  
Common Knowledge ◽  
Building Blocks ◽  
Tissue Level ◽  
Cortical Layer ◽  
Data Driven ◽  
Horizontal Connections ◽  
Cortical Laminar ◽  
And Function ◽  
White Matter Connectivity

AbstractOver the past two centuries, great scientific efforts have been spent on deciphering the structure and function of the cerebral cortex using a wide variety of methods. Since the advent of MRI neuroimaging, significant progress has been made in imaging of global white matter connectivity (connectomics), followed by promising new studies regarding imaging of grey matter laminar compartments. Despite progress in both fields, there still lacks mesoscale information regarding cortical laminar connectivity that could potentially bridge the gap between the current resolution of connectomics and the relatively higher resolution of cortical laminar imaging. Here, we systematically review a sample of prominent published articles regarding cortical laminar connectivity, in order to offer a simplified data-driven model that integrates white and grey matter MRI datasets into a novel way of exploring whole-brain tissue-level connectivity. Although it has been widely accepted that the cortex is exceptionally organized and interconnected, studies on the subject display a variety of approaches towards its structural building blocks. Our model addresses three principal cortical building blocks: cortical layer definitions (laminar grouping), vertical connections (intraregional, within the cortical microcircuit and subcortex) and horizontal connections (interregional, including connections within and between the hemispheres). While cortical partitioning into layers is more widely accepted as common knowledge, certain aspects of others such as cortical columns or microcircuits are still being debated. This study offers a broad and simplified view of histological and microscopical knowledge in laminar research that is applicable to the limitations of MRI methodologies, primarily regarding specificity and resolution.

scholarly journals Modelling cortical laminar connectivity in the macaque brain

2020 ◽  
Author(s):  
Ittai Shamir ◽  
Yaniv Assaf
Keyword(s):  
Visual Cortex ◽  
Grey Matter ◽  
Ex Vivo ◽  
Brain Mri ◽  
Structural Connectivity ◽  
Brain Network ◽  
Mri Imaging ◽  
Whole Brain ◽  
Hierarchical Processing ◽  
Cortical Laminar

AbstractIn 1991, Felleman and Van Essen published their seminal study regarding hierarchical processing in the primate cerebral cortex. Their work encompassed a widescale analysis of connections reported through tracing between 35 regions in the macaque visual cortex, extending from cortical regions to the laminar level. Since then, great strides have been made in the field of MRI neuroimaging of white matter connectivity, also known as structural connectomics, as well as grey matter laminar composition. In this work, we revisit laminar-level connectivity in the macaque brain using a whole-brain MRI-based approach. We use multi-modal ex-vivo MRI imaging of the macaque brain in both white and grey matter, which are then integrated via a simple model of laminar connectivity. This model uses a granularity-based approach to define a set of rules that expands cortical connections to the laminar level. The resulting whole-brain network of macaque cortical laminar connectivity is then validated in the visual cortex by comparison to results from the 1991 study by Felleman and Van Essen. By using an unbiased definition of the cortex that addresses its heterogenous laminar composition, we are able to explore a new avenue of structural connectivity on the laminar level.

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