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Reveley C, Ye FQ, Leopold DA. Diffusion kurtosis MRI tracks gray matter myelin content in the primate cerebral cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.08.584058. [PMID: 38496676 PMCID: PMC10942417 DOI: 10.1101/2024.03.08.584058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Diffusion magnetic resonance imaging (dMRI) has been widely employed to model the trajectory of myelinated fiber bundles in white matter. Increasingly, dMRI is also used to assess local tissue properties throughout the brain. In the cerebral cortex, myelin content is a critical indicator of the maturation, regional variation, and disease related degeneration of gray matter tissue. Gray matter myelination can be measured and mapped using several non-diffusion MRI strategies; however, first order diffusion statistics such as fractional anisotropy (FA) show only weak spatial correlation with cortical myelin content. Here we show that a simple higher order diffusion parameter, the mean diffusion kurtosis (MK), is strongly correlated with the laminar and regional variation of myelin in the primate cerebral cortex. We carried out ultra-high resolution, multi-shelled dMRI in ex vivo marmoset monkey brains and compared dMRI parameters from a number of higher order models (diffusion kurtosis, NODDI and MAP MRI) to the distribution of myelin obtained using histological staining, and via Magnetization Transfer Ratio MRI (MTR), a non-diffusion MRI method. In contrast to FA, MK closely matched the myelin content assessed by histology and by MTR in the same sample. The parameter maps from MAP-MRI and NODDI also showed good correspondence with cortical myelin content. The results demonstrate that dMRI can be used to assess the variation of local myelin content in the primate cortical cortex, which may be of great value for assessing tissue integrity and tracking disease in living human patients.
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Affiliation(s)
- Colin Reveley
- Wellcome Centre for Integrative Neuroimaging, Centre for fMRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Headington, Oxford, OX9 3DU, UK
| | - Frank Q Ye
- Neurophysiology Imaging Facility, National Institute of Mental Health, National Institute of Neurological Disorders and Stroke, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - David A Leopold
- Neurophysiology Imaging Facility, National Institute of Mental Health, National Institute of Neurological Disorders and Stroke, National Eye Institute, National Institutes of Health, Bethesda, MD
- Section on Cognitive Neurophysiology and Imaging, Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD
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2
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Wang J, Du X, Yao S, Li L, Tanigawa H, Zhang X, Roe AW. Mesoscale organization of ventral and dorsal visual pathways in macaque monkey revealed by 7T fMRI. Prog Neurobiol 2024; 234:102584. [PMID: 38309458 DOI: 10.1016/j.pneurobio.2024.102584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 01/26/2024] [Accepted: 01/29/2024] [Indexed: 02/05/2024]
Abstract
In human and nonhuman primate brains, columnar (mesoscale) organization has been demonstrated to underlie both lower and higher order aspects of visual information processing. Previous studies have focused on identifying functional preferences of mesoscale domains in specific areas; but there has been little understanding of how mesoscale domains may cooperatively respond to single visual stimuli across dorsal and ventral pathways. Here, we have developed ultrahigh-field 7 T fMRI methods to enable simultaneous mapping, in individual macaque monkeys, of response in both dorsal and ventral pathways to single simple color and motion stimuli. We provide the first evidence that anatomical V2 cytochrome oxidase-stained stripes are well aligned with fMRI maps of V2 stripes, settling a long-standing controversy. In the ventral pathway, a systematic array of paired color and luminance processing domains across V4 was revealed, suggesting a novel organization for surface information processing. In the dorsal pathway, in addition to high quality motion direction maps of MT, MST and V3A, alternating color and motion direction domains in V3 are revealed. As well, submillimeter motion domains were observed in peripheral LIPd and LIPv. In sum, our study provides a novel global snapshot of how mesoscale networks in the ventral and dorsal visual pathways form the organizational basis of visual objection recognition and vision for action.
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Affiliation(s)
- Jianbao Wang
- Department of Neurosurgery of the Second Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China; MOE Frontier Science Center for Brain Science and Brain-machine Integration, Zhejiang University, Hangzhou, China
| | - Xiao Du
- Department of Neurosurgery of the Second Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Songping Yao
- Department of Neurosurgery of the Second Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China; Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, China
| | - Lihui Li
- Department of Neurosurgery of the Second Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China; Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, China
| | - Hisashi Tanigawa
- Department of Neurosurgery of the Second Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China; MOE Frontier Science Center for Brain Science and Brain-machine Integration, Zhejiang University, Hangzhou, China
| | - Xiaotong Zhang
- Department of Neurosurgery of the Second Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China; Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, China; MOE Frontier Science Center for Brain Science and Brain-machine Integration, Zhejiang University, Hangzhou, China; College of Electrical Engineering, Zhejiang University, Hangzhou, China.
| | - Anna Wang Roe
- Department of Neurosurgery of the Second Affiliated Hospital, Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou, China; Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, China; MOE Frontier Science Center for Brain Science and Brain-machine Integration, Zhejiang University, Hangzhou, China.
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3
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Kruggel F, Solodkin A. Analyzing the cortical fine structure as revealed by ex-vivo anatomical MRI. J Comp Neurol 2023; 531:2146-2161. [PMID: 37522626 DOI: 10.1002/cne.25532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 04/15/2023] [Accepted: 06/21/2023] [Indexed: 08/01/2023]
Abstract
The human cortex has a rich fiber structure as revealed by myelin-staining of histological slices. Myelin also contributes to the image contrast in Magnetic Resonance Imaging (MRI). Recent advances in Magnetic Resonance (MR) scanner and imaging technology allowed the acquisition of an ex-vivo data set at an isotropic resolution of 100 µm. This study focused on a computational analysis of this data set with the aim of bridging between histological knowledge and MRI-based results. This work highlights: (1) the design and implementation of a processing chain that extracts intracortical features from a high-resolution MR image; (2) a demonstration of the correspondence between MRI-based cortical intensity profiles and the myelo-architectonic layering of the cortex; (3) the characterization and classification of four basic myelo-architectonic profile types; (4) the distinction of cortical regions based on myelo-architectonic features; and (5) the segmentation of cortical modules in the entorhinal cortex.
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Affiliation(s)
- Frithjof Kruggel
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, USA
| | - Ana Solodkin
- School of Behavioral and Brain Sciences, University of Texas, Richardson, Texas, USA
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4
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Reveley C, Ye FQ, Mars RB, Matrov D, Chudasama Y, Leopold DA. Diffusion MRI anisotropy in the cerebral cortex is determined by unmyelinated tissue features. Nat Commun 2022; 13:6702. [PMID: 36335105 PMCID: PMC9637141 DOI: 10.1038/s41467-022-34328-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/19/2022] [Indexed: 11/07/2022] Open
Abstract
Diffusion magnetic resonance imaging (dMRI) is commonly used to assess the tissue and cellular substructure of the human brain. In the white matter, myelinated axons are the principal neural elements that shape dMRI through the restriction of water diffusion; however, in the gray matter the relative contributions of myelinated axons and other tissue features to dMRI are poorly understood. Here we investigate the determinants of diffusion in the cerebral cortex. Specifically, we ask whether myelinated axons significantly shape dMRI fractional anisotropy (dMRI-FA), a measure commonly used to characterize tissue properties in humans. We compared ultra-high resolution ex vivo dMRI data from the brain of a marmoset monkey with both myelin- and Nissl-stained histological sections obtained from the same brain after scanning. We found that the dMRI-FA did not match the spatial distribution of myelin in the gray matter. Instead dMRI-FA was more closely related to the anisotropy of stained tissue features, most prominently those revealed by Nissl staining and to a lesser extent those revealed by myelin staining. Our results suggest that unmyelinated neurites such as large caliber apical dendrites are the primary features shaping dMRI measures in the cerebral cortex.
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Affiliation(s)
- Colin Reveley
- grid.4991.50000 0004 1936 8948Wellcome Centre for Integrative Neuroimaging, Centre for fMRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Headington, Oxford, OX9 3DU UK ,grid.12082.390000 0004 1936 7590Department of Informatics, University of Sussex, Falmer, Brighton, BN1 9QJ UK
| | - Frank Q. Ye
- grid.94365.3d0000 0001 2297 5165Neurophysiology Imaging Facility, National Institute of Mental Health, National Institute of Neurological Disorders and Stroke, National Eye Institute, National Institutes of Health, Bethesda, MD USA
| | - Rogier B. Mars
- grid.4991.50000 0004 1936 8948Wellcome Centre for Integrative Neuroimaging, Centre for fMRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Headington, Oxford, OX9 3DU UK ,grid.5590.90000000122931605Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Denis Matrov
- grid.94365.3d0000 0001 2297 5165Section on Behavioral Neuroscience, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA
| | - Yogita Chudasama
- grid.94365.3d0000 0001 2297 5165Section on Behavioral Neuroscience, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA
| | - David A. Leopold
- grid.94365.3d0000 0001 2297 5165Neurophysiology Imaging Facility, National Institute of Mental Health, National Institute of Neurological Disorders and Stroke, National Eye Institute, National Institutes of Health, Bethesda, MD USA ,grid.94365.3d0000 0001 2297 5165Section on Cognitive Neurophysiology and Imaging, Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA
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5
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A set of hub neurons and non-local connectivity features support global brain dynamics in C. elegans. Curr Biol 2022; 32:3443-3459.e8. [PMID: 35809568 DOI: 10.1016/j.cub.2022.06.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 05/17/2022] [Accepted: 06/13/2022] [Indexed: 11/20/2022]
Abstract
The wiring architecture of neuronal networks is assumed to be a strong determinant of their dynamical computations. An ongoing effort in neuroscience is therefore to generate comprehensive synapse-resolution connectomes alongside brain-wide activity maps. However, the structure-function relationship, i.e., how the anatomical connectome and neuronal dynamics relate to each other on a global scale, remains unsolved. Systematically, comparing graph features in the C. elegans connectome with correlations in nervous system-wide neuronal dynamics, we found that few local connectivity motifs and mostly other non-local features such as triplet motifs and input similarities can predict functional relationships between neurons. Surprisingly, quantities such as connection strength and amount of common inputs do not improve these predictions, suggesting that the network's topology is sufficient. We demonstrate that hub neurons in the connectome are key to these relevant graph features. Consistently, inhibition of multiple hub neurons specifically disrupts brain-wide correlations. Thus, we propose that a set of hub neurons and non-local connectivity features provide an anatomical substrate for global brain dynamics.
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6
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Homman-Ludiye J, Bourne JA. The Marmoset: The Next Frontier in Understanding the Development of the Human Brain. ILAR J 2021; 61:248-259. [PMID: 33620074 DOI: 10.1093/ilar/ilaa028] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 11/13/2020] [Accepted: 11/20/2020] [Indexed: 12/22/2022] Open
Abstract
Rodent models, particularly mice, have dominated the field of developmental neuroscience for decades, like they have in most fields of biomedicine research. However, with 80 million years since rodents and primates last shared a common ancestor, the use of mice to model the development of the human brain is not without many shortcomings. The human brain diverges from the mouse brain in many aspects and is comprised of novel structures as well as diversified cellular subtypes. While these newly evolved features have no equivalent in rodents, they are observed in nonhuman primates. Therefore, elucidating the cellular mechanisms underlying the development and maturation of the healthy and diseased human brain can be achieved using less complex nonhuman primates. Historically, macaques were the preferred nonhuman primate model. However, over the past decade, the New World marmoset monkey (Callithrix jacchus) has gained more importance, particularly in the field of neurodevelopment. With its small size, twin or triplet birth, and prosocial behavior, the marmoset is an ideal model to study normal brain development as well as neurodevelopmental disorders, which are often associated with abnormal social behaviors. The growing interest in the marmoset has prompted many comparative studies, all demonstrating that the marmoset brain closely resembles that of the human and is perfectly suited to model human brain development. The marmoset is thus poised to extend its influence in the field of neurodevelopment and will hopefully fill the gaps that the mouse has left in our understanding of how our brain forms and how neurodevelopmental disorders originate.
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Affiliation(s)
- Jihane Homman-Ludiye
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia
| | - James A Bourne
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia
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7
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Grydeland H, Vértes PE, Váša F, Romero-Garcia R, Whitaker K, Alexander-Bloch AF, Bjørnerud A, Patel AX, Sederevicius D, Tamnes CK, Westlye LT, White SR, Walhovd KB, Fjell AM, Bullmore ET. Waves of Maturation and Senescence in Micro-structural MRI Markers of Human Cortical Myelination over the Lifespan. Cereb Cortex 2020; 29:1369-1381. [PMID: 30590439 PMCID: PMC6373687 DOI: 10.1093/cercor/bhy330] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 11/30/2018] [Indexed: 11/13/2022] Open
Abstract
Seminal human brain histology work has demonstrated developmental waves of myelination. Here, using a micro-structural magnetic resonance imaging (MRI) marker linked to myelin, we studied fine-grained age differences to deduce waves of growth, stability, and decline of cortical myelination over the life-cycle. In 484 participants, aged 8–85 years, we fitted smooth growth curves to T1- to T2-weighted ratio in each of 360 regions from one of seven cytoarchitectonic classes. From the first derivatives of these generally inverted-U trajectories, we defined three milestones: the age at peak growth; the age at onset of a stable plateau; and the age at the onset of decline. Age at peak growth had a bimodal distribution comprising an early (pre-pubertal) wave of primary sensory and motor cortices and a later (post-pubertal) wave of association, insular and limbic cortices. Most regions reached stability in the 30-s but there was a second wave reaching stability in the 50-s. Age at onset of decline was also bimodal: in some right hemisphere regions, the curve declined from the 60-s, but in other left hemisphere regions, there was no significant decline from the stable plateau. These results are consistent with regionally heterogeneous waves of intracortical myelinogenesis and age-related demyelination.
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Affiliation(s)
- Håkon Grydeland
- Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway
| | - Petra E Vértes
- Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - František Váša
- Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - Rafael Romero-Garcia
- Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - Kirstie Whitaker
- Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Cambridge, UK.,The Alan Turing Institute, British Library, London, UK
| | | | - Atle Bjørnerud
- Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway.,Department of Radiology and Nuclear Medicine, University of Oslo, Oslo, Norway
| | - Ameera X Patel
- Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - Donatas Sederevicius
- Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway
| | - Christian K Tamnes
- Department of Psychology, University of Oslo, Oslo, Norway.,Department of Psychiatry, Diakonhjemmet Hospital, Oslo, Norway
| | - Lars T Westlye
- Department of Psychology, University of Oslo, Oslo, Norway
| | - Simon R White
- MRC Biostatistics Unit, Cambridge Institute of Public Health, Cambridge University, Cambridge, UK
| | - Kristine B Walhovd
- Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway.,Department of Radiology and Nuclear Medicine, University of Oslo, Oslo, Norway
| | - Anders M Fjell
- Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway.,Department of Radiology and Nuclear Medicine, University of Oslo, Oslo, Norway
| | - Edward T Bullmore
- Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Cambridge, UK.,Cambridgeshire and Peterborough NHS Foundation Trust, Huntingdon, UK.,Immuno-Inflammation Therapeutic Area Unit, GlaxoSmithKline R&D, Stevenage, UK
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8
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Sprooten E, O'Halloran R, Dinse J, Lee WH, Moser DA, Doucet GE, Goodman M, Krinsky H, Paulino A, Rasgon A, Leibu E, Balchandani P, Inglese M, Frangou S. Depth-dependent intracortical myelin organization in the living human brain determined by in vivo ultra-high field magnetic resonance imaging. Neuroimage 2018; 185:27-34. [PMID: 30312809 DOI: 10.1016/j.neuroimage.2018.10.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 10/08/2018] [Accepted: 10/08/2018] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Intracortical myelin is a key determinant of neuronal synchrony and plasticity that underpin optimal brain function. Magnetic resonance imaging (MRI) facilitates the examination of intracortical myelin but presents with methodological challenges. Here we describe a whole-brain approach for the in vivo investigation of intracortical myelin in the human brain using ultra-high field MRI. METHODS Twenty-five healthy adults were imaged in a 7 Tesla MRI scanner using diffusion-weighted imaging and a T1-weighted sequence optimized for intracortical myelin contrast. Using an automated pipeline, T1 values were extracted at 20 depth-levels from each of 148 cortical regions. In each cortical region, T1 values were used to infer myelin concentration and to construct a non-linearity index as a measure the spatial distribution of myelin across the cortical ribbon. The relationship of myelin concentration and the non-linearity index with other neuroanatomical properties were investigated. Five patients with multiple sclerosis were also assessed using the same protocol as positive controls. RESULTS Intracortical T1 values decreased between the outer brain surface and the gray-white matter boundary following a slope that showed a slight leveling between 50% and 75% of cortical depth. Higher-order regions in the prefrontal, cingulate and insular cortices, displayed higher non-linearity indices than sensorimotor regions. Across all regions, there was a positive association between T1 values and non-linearity indices (P < 10-5). Both T1 values (P < 10-5) and non-linearity indices (P < 10-15) were associated with cortical thickness. Higher myelin concentration but only in the deepest cortical levels was associated with increased subcortical fractional anisotropy (P = 0.05). CONCLUSIONS We demonstrate the usefulness of an automatic, whole-brain method to perform depth-dependent examination of intracortical myelin organization. The extracted metrics, T1 values and the non-linearity index, have characteristic patterns across cortical regions, and are associated with thickness and underlying white matter microstructure.
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Affiliation(s)
- Emma Sprooten
- Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, the Netherlands; Department of Cognitive Neuroscience, Radboudumc, Nijmegen, the Netherlands
| | - Rafael O'Halloran
- Translational and Molecular Imaging Institute Translational and Molecular Imaging Institute and Brain Imaging Center, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Juliane Dinse
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Won Hee Lee
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Dominik Andreas Moser
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Gaelle Eve Doucet
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Morgan Goodman
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Hannah Krinsky
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Alejandro Paulino
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Alexander Rasgon
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Evan Leibu
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Priti Balchandani
- Translational and Molecular Imaging Institute Translational and Molecular Imaging Institute and Brain Imaging Center, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Matilde Inglese
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Sophia Frangou
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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9
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Beck ES, Sati P, Sethi V, Kober T, Dewey B, Bhargava P, Nair G, Cortese IC, Reich DS. Improved Visualization of Cortical Lesions in Multiple Sclerosis Using 7T MP2RAGE. AJNR Am J Neuroradiol 2018; 39:459-466. [PMID: 29439120 DOI: 10.3174/ajnr.a5534] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/15/2017] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Cortical lesions are common and often extensive in multiple sclerosis but are difficult to visualize by MRI, leaving important questions about their clinical implications and response to therapy unanswered. Our aim was to determine whether cortical lesions are better visualized using magnetization prepared 2 rapid acquisition gradient echoes (MP2RAGE) than T2*-weighted imaging on 7T MR imaging. MATERIALS AND METHODS Brain MR imaging using T1-weighted MP2RAGE at 500-μm isotropic resolution, T2*-weighted gradient-echo, and T2*-weighted segmented echo-planar imaging sequences were collected for 13 patients with MS and 5 age-matched neurologically healthy controls on a 7T research system. One MS case underwent postmortem MR imaging including gradient-echo and MP2RAGE sequences, after which cortical lesions seen on MR imaging were assessed with immunohistochemistry. RESULTS MP2RAGE detected 203 cortical lesions (median, 16 lesions/case; interquartile range, 15), compared to 92 with T2*gradient-echo (median, 7; interquartile range, 8; P < .001) and 81 with T2*EPI (median, 7; interquartile range, 5; P < .001). This increase in lesion number detected on MP2RAGE versus T2* was observed for juxtacortical, leukocortical, and intracortical lesions. Forty-three percent of all cortical lesions were identified only on MP2RAGE. White matter lesion volume correlated with total juxtacortical (r = 0.86, P < .001) and leukocortical lesion volume (r = 0.70, P < .01) but not intracortical lesion volume, suggesting that pathophysiology may differ by lesion type. Of 4 suspected lesions seen on postmortem imaging, 3 were found to be true cortical lesions while 1 represented postmortem tissue damage. CONCLUSIONS A combination of MP2RAGE and T2*-weighted imaging at 7T improved detection of cortical lesions and should enable longitudinal studies to elucidate their spatiotemporal dynamics and clinical implications.
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Affiliation(s)
- E S Beck
- From the Translational Neuroradiology Section (E.S.B., P.S., V.S., B.D., G.N., D.S.R.)
| | - P Sati
- From the Translational Neuroradiology Section (E.S.B., P.S., V.S., B.D., G.N., D.S.R.)
| | - V Sethi
- From the Translational Neuroradiology Section (E.S.B., P.S., V.S., B.D., G.N., D.S.R.)
| | - T Kober
- Advanced Clinical Imaging Technology Group (T.K.), Siemens Healthcare Switzerland, Lausanne, Switzerland.,Department of Radiology (T.K.), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.,LTS5, Ecole Polytechnique Fédérale de Lausanne (T.K.), Lausanne, Switzerland
| | - B Dewey
- From the Translational Neuroradiology Section (E.S.B., P.S., V.S., B.D., G.N., D.S.R.)
| | - P Bhargava
- Department of Neurology (P.B.), Johns Hopkins University, Baltimore, Maryland
| | - G Nair
- From the Translational Neuroradiology Section (E.S.B., P.S., V.S., B.D., G.N., D.S.R.)
| | - I C Cortese
- Neuroimmunology Clinic (I.C.C.), National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - D S Reich
- From the Translational Neuroradiology Section (E.S.B., P.S., V.S., B.D., G.N., D.S.R.)
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10
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Silva AC. Anatomical and functional neuroimaging in awake, behaving marmosets. Dev Neurobiol 2016; 77:373-389. [PMID: 27706916 DOI: 10.1002/dneu.22456] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/28/2016] [Accepted: 09/28/2016] [Indexed: 12/12/2022]
Abstract
The common marmoset (Callithrix jacchus) is a small New World monkey that has gained significant recent interest in neuroscience research, not only because of its compatibility with gene editing techniques, but also due to its tremendous versatility as an experimental animal model. Neuroimaging modalities, including anatomical (MRI) and functional magnetic resonance imaging (fMRI), complemented by two-photon laser scanning microscopy and electrophysiology, have been at the forefront of unraveling the anatomical and functional organization of the marmoset brain. High-resolution anatomical MRI of the marmoset brain can be obtained with remarkable cytoarchitectonic detail. Functional MRI of the marmoset brain has been used to study various sensory systems, including somatosensory, auditory, and visual pathways, while resting-state fMRI studies have unraveled functional brain networks that bear great correspondence to those previously described in humans. Two-photon laser scanning microscopy of the marmoset brain has enabled the simultaneous recording of neuronal activity from thousands of neurons with single cell spatial resolution. In this article, we aim to review the main results obtained by our group and by our colleagues in applying neuroimaging techniques to study the marmoset brain. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 373-389, 2017.
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Affiliation(s)
- Afonso C Silva
- Cerebral Microcirculation Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892
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11
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Chao LL, Tosun D, Woodward SH, Kaufer D, Neylan TC. Preliminary Evidence of Increased Hippocampal Myelin Content in Veterans with Posttraumatic Stress Disorder. Front Behav Neurosci 2015; 9:333. [PMID: 26696852 PMCID: PMC4667092 DOI: 10.3389/fnbeh.2015.00333] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Accepted: 11/19/2015] [Indexed: 01/06/2023] Open
Abstract
Recent findings suggest the formation of myelin in the central nervous system by oligodendrocytes is a continuous process that can be modified with experience. For example, a recent study showed that immobilization stress increased oligodendrogensis in the dentate gyrus of adult rat hippocampus. Because changes in myelination represents an adaptive form of brain plasticity that has a greater reach in the adult brain than other forms of plasticity (e.g., neurogenesis), the objective of this “proof of concept” study was to examine whether there are differences in myelination in the hippocampi of humans with and without post-traumatic stress disorder (PTSD). We used the ratio of T1-weighted/T2-weighted magnetic resonance image (MRI) intensity to estimate the degree of hippocampal myelination in 19 male veterans with PTSD and 19 matched trauma-exposed male veterans without PTSD (mean age: 43 ± 12 years). We found that veterans with PTSD had significantly more hippocampal myelin than trauma-exposed controls. There was also found a positive correlation between estimates of hippocampal myelination and PTSD and depressive symptom severity. To our knowledge, this is the first study to examine hippocampal myelination in humans with PTSD. These results provide preliminary evidence for stress-induced hippocampal myelin formation as a potential mechanism underlying the brain abnormalities associated with vulnerability to stress.
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Affiliation(s)
- Linda L Chao
- Center for Imaging of Neurodegenerative Diseases, Veterans Affairs Medical Center San Francisco, CA, USA ; Department of Radiology and Biomedical Imaging, University of California San Francisco, CA, USA ; Department of Psychiatry, University of California San Francisco, CA, USA
| | - Duygu Tosun
- Center for Imaging of Neurodegenerative Diseases, Veterans Affairs Medical Center San Francisco, CA, USA ; Department of Radiology and Biomedical Imaging, University of California San Francisco, CA, USA
| | - Steven H Woodward
- Dissemination and Training Division, National Center for PTSD, VA Palo Alto Health Care System CA, USA
| | - Daniela Kaufer
- Helen Wills Neuroscience Institute, University of California Berkeley, CA, USA ; Department of Integrative Biology, University of California Berkeley, CA, USA ; Canadian Institute for Advanced Research (CIFAR) Toronto, ON, Canada
| | - Thomas C Neylan
- Department of Psychiatry, University of California San Francisco, CA, USA ; Mental Health Services, Veterans Affairs Medical Center San Francisco, CA, USA
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12
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Schultz-Darken N, Braun KM, Emborg ME. Neurobehavioral development of common marmoset monkeys. Dev Psychobiol 2015; 58:141-58. [PMID: 26502294 DOI: 10.1002/dev.21360] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 09/07/2015] [Indexed: 11/06/2022]
Abstract
Common marmoset (Callithrix jacchus) monkeys are a resource for biomedical research and their use is predicted to increase due to the suitability of this species for transgenic approaches. Identification of abnormal neurodevelopment due to genetic modification relies upon the comparison with validated patterns of normal behavior defined by unbiased methods. As scientists unfamiliar with nonhuman primate development are interested to apply genomic editing techniques in marmosets, it would be beneficial to the field that the investigators use validated methods of postnatal evaluation that are age and species appropriate. This review aims to analyze current available data on marmoset physical and behavioral postnatal development, describe the methods used and discuss next steps to better understand and evaluate marmoset normal and abnormal postnatal neurodevelopment.
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Affiliation(s)
- Nancy Schultz-Darken
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI
| | - Katarina M Braun
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI.,Medical Scientist Training Program, University of Wisconsin, Madison, WI
| | - Marina E Emborg
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI.,Medical Scientist Training Program, University of Wisconsin, Madison, WI.,Department of Medical Physics, University of Wisconsin, Madison, WI
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13
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Hung CC, Yen CC, Ciuchta JL, Papoti D, Bock NA, Leopold DA, Silva AC. Functional MRI of visual responses in the awake, behaving marmoset. Neuroimage 2015; 120:1-11. [PMID: 26149609 DOI: 10.1016/j.neuroimage.2015.06.090] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 06/09/2015] [Accepted: 06/30/2015] [Indexed: 10/23/2022] Open
Abstract
The visual brain is composed of interconnected subcortical and cortical structures that receive and process image information originating in the retina. The visual system of nonhuman primates, in particular macaques, has been studied in great detail in order to elucidate principles of human sensation and perception. The common marmoset (Callithrix jacchus) is a small New World monkey of growing interest as a primate model for neuroscience. Marmosets have advantages over macaques because of their small size, lissencephalic cortex, and growing potential for viral and genetic manipulations. Previous anatomical studies and electrophysiological recordings in anesthetized marmosets have shown that this species' cortical visual hierarchy closely resembles that of other primates, including humans. Until now, however, there have been no attempts to systematically study visual responses throughout the marmoset brain using fMRI. Here we show that awake marmosets readily learn to carry out a simple visual task inside the bore of an MRI scanner during functional mapping experiments. Functional scanning at 500 μm in-plane resolution in a 30 cm horizontal bore at 7 T revealed robust positive blood oxygenation level-dependent (BOLD) fMRI responses to visual stimuli throughout visual cortex and associated subcortical areas. Nonvisual sensory areas showed negative contrasts to visual stimuli compared to the fixation dot only baseline. Structured images of objects and faces led to stronger responses than scrambled control images at stages beyond early visual cortex. Our study establishes fMRI mapping of visual responses in awake, behaving marmosets as a straightforward and valuable tool for assessing the functional organization of the primate brain at high resolution.
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Affiliation(s)
- Chia-Chun Hung
- Cerebral Microcirculation Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA; Section on Cognitive Neurophysiology and Imaging, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD, 20892, USA
| | - Cecil C Yen
- Cerebral Microcirculation Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jennifer L Ciuchta
- Cerebral Microcirculation Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Daniel Papoti
- Cerebral Microcirculation Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Nicholas A Bock
- Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
| | - David A Leopold
- Section on Cognitive Neurophysiology and Imaging, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD, 20892, USA; Neurophysiology Imaging Facility, National Institute of Mental Health, National Institute of Neurological Disorders and Stroke, National Eye Institute, Bethesda, MD, 20892, USA
| | - Afonso C Silva
- Cerebral Microcirculation Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
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14
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Grydeland H, Westlye LT, Walhovd KB, Fjell AM. Intracortical Posterior Cingulate Myelin Content Relates to Error Processing: Results fromT1- andT2-Weighted MRI Myelin Mapping and Electrophysiology in Healthy Adults. Cereb Cortex 2015; 26:2402-10. [DOI: 10.1093/cercor/bhv065] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Abstract
The cerebral cortex of humans and macaques has specialized regions for processing faces and other visual stimulus categories. It is unknown whether a similar functional organization exists in New World monkeys, such as the common marmoset (Callithrix jacchus), a species of growing interest as a primate model in neuroscience. To address this question, we measured selective neural responses in the brain of four awake marmosets trained to fix their gaze upon images of faces, bodies, objects, and control patterns. In two of the subjects, we measured high gamma-range field potentials from electrocorticography arrays implanted over a large portion of the occipital and inferotemporal cortex. In the other two subjects, we measured BOLD fMRI responses across the entire brain. Both techniques revealed robust, regionally specific patterns of category-selective neural responses. We report that at least six face-selective patches mark the occipitotemporal pathway of the marmoset, with the most anterior patches showing the strongest preference for faces over other stimuli. The similar appearance of these patches to previous findings in macaques and humans, including their apparent arrangement in two parallel pathways, suggests that core elements of the face processing network were present in the common anthropoid primate ancestor living ∼35 million years ago. The findings also identify the marmoset as a viable animal model system for studying specialized neural mechanisms related to high-level social visual perception in humans.
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16
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Gray matter myelination of 1555 human brains using partial volume corrected MRI images. Neuroimage 2014; 105:473-85. [PMID: 25449739 DOI: 10.1016/j.neuroimage.2014.10.054] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 09/19/2014] [Accepted: 10/19/2014] [Indexed: 11/23/2022] Open
Abstract
The myelin content of the cortex changes over the human lifetime and aberrant cortical myelination is associated with diseases such as schizophrenia and multiple sclerosis. Recently magnetic resonance imaging (MRI) techniques have shown potential in differentiating between myeloarchitectonically distinct cortical regions in vivo. Here we introduce a new algorithm for correcting partial volume effects present in mm-scale MRI images which was used to investigate the myelination pattern of the cerebral cortex in 1555 clinically normal subjects using the ratio of T1-weighted (T1w) and T2-weighted (T2w) MRI images. A significant linear cross-sectional age increase in T1w/T2w estimated myelin was detected across an 18 to 35 year age span (highest value of ~ 1%/year compared to mean T1w/T2w myelin value at 18 years). The cortex was divided at mid-thickness and the value of T1w/T2w myelin calculated for the inner and outer layers separately. The increase in T1w/T2w estimated myelin occurs predominantly in the inner layer for most cortical regions. The ratio of the inner and outer layer T1w/T2w myelin was further validated using high-resolution in vivo MRI scans and also a high-resolution MRI scan of a postmortem brain. Additionally, the relationships between cortical thickness, curvature and T1w/T2w estimated myelin were found to be significant, although the relationships varied across the cortex. We discuss these observations as well as limitations of using the T1w/T2w ratio as an estimate of cortical myelin.
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17
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De Martino F, Moerel M, Xu J, van de Moortele PF, Ugurbil K, Goebel R, Yacoub E, Formisano E. High-Resolution Mapping of Myeloarchitecture In Vivo: Localization of Auditory Areas in the Human Brain. Cereb Cortex 2014; 25:3394-405. [PMID: 24994817 DOI: 10.1093/cercor/bhu150] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The precise delineation of auditory areas in vivo remains problematic. Histological analysis of postmortem tissue indicates that the relation of areal borders to macroanatomical landmarks is variable across subjects. Furthermore, functional parcellation schemes based on measures of, for example, frequency preference (tonotopy) remain controversial. Here, we propose a 7 Tesla magnetic resonance imaging method that enables the anatomical delineation of auditory cortical areas in vivo and in individual brains, through the high-resolution visualization (0.6 × 0.6 × 0.6 mm(3)) of intracortical anatomical contrast related to myelin. The approach combines the acquisition and analysis of images with multiple MR contrasts (T1, T2*, and proton density). Compared with previous methods, the proposed solution is feasible at high fields and time efficient, which allows collecting myelin-related and functional images within the same measurement session. Our results show that a data-driven analysis of cortical depth-dependent profiles of anatomical contrast allows identifying a most densely myelinated cortical region on the medial Heschl's gyrus. Analyses of functional responses show that this region includes neuronal populations with typical primary functional properties (single tonotopic gradient and narrow frequency tuning), thus indicating that it may correspond to the human homolog of monkey A1.
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Affiliation(s)
- Federico De Martino
- Department of Cognitive Neurosciences, Faculty of Psychology and Neuroscience, Maastricht University, 6229 ER Maastricht, The Netherlands Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, 55455 Minneapolis, MN, USA
| | - Michelle Moerel
- Department of Cognitive Neurosciences, Faculty of Psychology and Neuroscience, Maastricht University, 6229 ER Maastricht, The Netherlands
| | - Junqian Xu
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, 55455 Minneapolis, MN, USA Icahn School of Medicine Mount Sinai, 10029-6574 New York, NY, USA
| | | | - Kamil Ugurbil
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, 55455 Minneapolis, MN, USA
| | - Rainer Goebel
- Department of Cognitive Neurosciences, Faculty of Psychology and Neuroscience, Maastricht University, 6229 ER Maastricht, The Netherlands
| | - Essa Yacoub
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, 55455 Minneapolis, MN, USA
| | - Elia Formisano
- Department of Cognitive Neurosciences, Faculty of Psychology and Neuroscience, Maastricht University, 6229 ER Maastricht, The Netherlands
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18
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Miller DJ, Lackey EP, Hackett TA, Kaas JH. Development of myelination and cholinergic innervation in the central auditory system of a prosimian primate (Otolemur garnetti). J Comp Neurol 2014; 521:3804-16. [PMID: 23749337 DOI: 10.1002/cne.23379] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 05/22/2013] [Accepted: 05/23/2013] [Indexed: 11/07/2022]
Abstract
Change in the timeline of neurobiological growth is an important source of biological variation, and thus phenotypic evolution. However, no study has to date investigated sensory system development in any of the prosimian primates that are thought to most closely resemble our earliest primate ancestors. Acetylcholine (ACh) is a neurotransmitter critical to normal brain function by regulating synaptic plasticity associated with attention and learning. Myelination is an important structural component of the brain because it facilitates rapid neuronal communication. In this work we investigated the expression of acetylcholinesterase (AChE) and the density of myelinated axons throughout postnatal development in the inferior colliculus (IC), medial geniculate complex (MGC), and auditory cortex (auditory core, belt, and parabelt) in Garnett's greater galago (Otolemur garnetti). We found that the IC and MGC exhibit relatively high myelinated fiber length density (MFLD) values at birth and attain adult-like values by the species-typical age at weaning. In contrast, neocortical auditory fields are relatively unmyelinated at birth and only attain adult-like MFLD values by the species-typical age at puberty. Analysis of AChE expression indicated that, in contrast to evidence from rodent samples, the adult-like distribution of AChE in the core area of auditory cortex, dense bands in layers I, IIIb/IV, and Vb/VI, is present at birth. These data indicate the differential developmental trajectory of central auditory system structures and demonstrate the early onset of adult-like AChE expression in primary auditory cortex in O. garnetti, suggesting the auditory system is more developed at birth in primates compared to rodents.
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Affiliation(s)
- Daniel J Miller
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, 37205
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19
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Delineating extrastriate visual area MT(V5) using cortical myeloarchitecture. Neuroimage 2014; 93 Pt 2:231-6. [DOI: 10.1016/j.neuroimage.2013.03.034] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 03/11/2013] [Accepted: 03/19/2013] [Indexed: 11/17/2022] Open
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20
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Intracortical myelin links with performance variability across the human lifespan: results from T1- and T2-weighted MRI myelin mapping and diffusion tensor imaging. J Neurosci 2014; 33:18618-30. [PMID: 24259583 DOI: 10.1523/jneurosci.2811-13.2013] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Cerebral myelin maturation and aging-related degradation constitute fundamental features of human brain integrity and functioning. Although mostly studied in the white matter, the cerebral cortex contains significant amounts of myelinated axons. However, how intracortical myelin content evolves during development, decays in aging, and links with cognition remain poorly understood. Several studies have shown the potential of mapping myelin in the cortex by use of T1-weighted (T1w) and T2-weighted (T2w) magnetic resonance imaging signal intensity, which show inverse sensitivity to myelin. Here, we characterized cortical myelin in 339 participants 8-83 years of age using a recently introduced T1w/T2w ratio myelin mapping technique and mean diffusivity (MD) from diffusion tensor imaging. To test for cognitive correlates, we used intraindividual variability (IIV) in performance during a speeded task, a measure recently associated with white matter integrity. The results showed that intracortical myelin maturation was ongoing until the late 30s, followed by 20 relative stable years before declining from the late 50s. For MD, U-shaped paths showing similar patterns were observed, but with fewer maturational effects in some regions. IIV was correlated with both T1w/T2w ratio and MD, mainly indicating that the higher degree of intracortical myelin is associated with greater performance stability. The relations were more prominent with advancing age, suggesting that aging-related cortical demyelination contributes to increased IIV. The T1w/T2w ratio myelin-mapping technique thus seems sensitive to intracortical myelin content in normal development and aging, relates to cognitive functioning, and might constitute an important future tool in mapping normal and clinical brain changes.
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21
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Baumann S, Petkov CI, Griffiths TD. A unified framework for the organization of the primate auditory cortex. Front Syst Neurosci 2013; 7:11. [PMID: 23641203 PMCID: PMC3639404 DOI: 10.3389/fnsys.2013.00011] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 04/12/2013] [Indexed: 11/24/2022] Open
Abstract
In non-human primates a scheme for the organization of the auditory cortex is frequently used to localize auditory processes. The scheme allows a common basis for comparison of functional organization across non-human primate species. However, although a body of functional and structural data in non-human primates supports an accepted scheme of nearly a dozen neighboring functional areas, can this scheme be directly applied to humans? Attempts to expand the scheme of auditory cortical fields in humans have been severely hampered by a recent controversy about the organization of tonotopic maps in humans, centered on two different models with radically different organization. We point out observations that reconcile the previous models and suggest a distinct model in which the human cortical organization is much more like that of other primates. This unified framework allows a more robust and detailed comparison of auditory cortex organization across primate species including humans.
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Affiliation(s)
- Simon Baumann
- Medical Faculty, Institute of Neuroscience, Newcastle University Newcastle upon Tyne, UK
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22
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Liu JV, Hirano Y, Nascimento GC, Stefanovic B, Leopold DA, Silva AC. fMRI in the awake marmoset: somatosensory-evoked responses, functional connectivity, and comparison with propofol anesthesia. Neuroimage 2013; 78:186-95. [PMID: 23571417 DOI: 10.1016/j.neuroimage.2013.03.038] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 02/21/2013] [Accepted: 03/14/2013] [Indexed: 01/20/2023] Open
Abstract
Functional neuroimaging in animal models is essential for understanding the principles of neurovascular coupling and the physiological basis of fMRI signals that are widely used to study sensory and cognitive processing in the human brain. While hemodynamic responses to sensory stimuli have been characterized in humans, animal studies are able to combine very high resolution imaging with invasive measurements and pharmacological manipulation. To date, most high-resolution studies of neurovascular coupling in small animals have been carried out in anesthetized rodents. Here we report fMRI experiments in conscious, awake common marmosets (Callithrix jacchus), and compare responses to animals anesthetized with propofol. In conscious marmosets, robust BOLD fMRI responses to somatosensory stimulation of the forearm were found in contralateral and ipsilateral regions of the thalamus, primary (SI) and secondary (SII) somatosensory cortex, and the caudate nucleus. These responses were markedly stronger than those in anesthetized marmosets and showed a monotonic increase in the amplitude of the BOLD response with stimulus frequency. On the other hand, anesthesia significantly attenuated responses in thalamus, SI and SII, and abolished responses in caudate and ipsilateral SI. Moreover, anesthesia influenced several other aspects of the fMRI responses, including the shape of the hemodynamic response function and the interareal (SI-SII) spontaneous functional connectivity. Together, these findings demonstrate the value of the conscious, awake marmoset model for studying physiological responses in the somatosensory pathway, in the absence of anesthesia, so that the data can be compared most directly to fMRI in conscious humans.
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Affiliation(s)
- Junjie V Liu
- Cerebral Microcirculation Unit, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive, Building 10, Room B1D106, Bethesda, MD 20892, USA.
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23
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Glasser MF, Goyal MS, Preuss TM, Raichle ME, Van Essen DC. Trends and properties of human cerebral cortex: correlations with cortical myelin content. Neuroimage 2013; 93 Pt 2:165-75. [PMID: 23567887 DOI: 10.1016/j.neuroimage.2013.03.060] [Citation(s) in RCA: 281] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 03/12/2013] [Accepted: 03/23/2013] [Indexed: 10/27/2022] Open
Abstract
"In vivo Brodmann mapping" or non-invasive cortical parcellation using MRI, especially by measuring cortical myelination, has recently become a popular research topic, though myeloarchitectonic cortical parcellation in humans previously languished in favor of cytoarchitecture. We review recent in vivo myelin mapping studies and discuss some of the different methods for estimating myelin content. We discuss some ways in which myelin maps may improve surface registration and be useful for cross-modal and cross-species comparisons, including some preliminary cross-species results. Next, we consider neurobiological aspects of why some parts of cortex are more myelinated than others. Myelin content is inversely correlated with intracortical circuit complexity - in general, more myelin content means simpler and perhaps less dynamic intracortical circuits. Using existing PET data and functional network parcellations, we examine metabolic differences in the differently myelinated cortical functional networks. Lightly myelinated cognitive association networks tend to have higher aerobic glycolysis than heavily myelinated early sensory-motor ones, perhaps reflecting greater ongoing dynamic anabolic cortical processes. This finding is consistent with the hypothesis that intracortical myelination may stabilize intracortical circuits and inhibit synaptic plasticity. Finally, we discuss the future of the in vivo myeloarchitectural field and cortical parcellation--"in vivo Brodmann mapping"--in general.
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Affiliation(s)
- Matthew F Glasser
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA.
| | - Manu S Goyal
- Department of Radiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA.
| | - Todd M Preuss
- Division of Neuropharmacology and Neurologic Diseases, Emory University, Atlanta, GA 30329, USA; Center for Translational and Social Neuroscience, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA; Department of Pathology, Emory University School of Medicine, Atlanta, GA 30329, USA.
| | - Marcus E Raichle
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA; Department of Radiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA; Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA.
| | - David C Van Essen
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA.
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24
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Helms G, Garea-Rodriguez E, Schlumbohm C, König J, Dechent P, Fuchs E, Wilke M. Structural and quantitative neuroimaging of the common marmoset monkey using a clinical MRI system. J Neurosci Methods 2013; 215:121-31. [DOI: 10.1016/j.jneumeth.2013.02.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 01/19/2013] [Accepted: 02/14/2013] [Indexed: 01/02/2023]
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25
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Origin of B0 orientation dependent R2(*) (=1/T2(*)) in white matter. Neuroimage 2013; 73:71-9. [PMID: 23376494 DOI: 10.1016/j.neuroimage.2013.01.051] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 01/20/2013] [Accepted: 01/24/2013] [Indexed: 12/20/2022] Open
Abstract
Recent MRI studies have demonstrated that the relative orientation of white matter fibers to the B0 field significantly affects R2(*) measurement. In this work, the origin of this effect was investigated by measuring R2 and R2(*) in multiple orientations and fitting the results to magnetic susceptibility-based models and magic angle-based models. To further explore the source of magnetic susceptibility effect, the contribution of tissue iron to the orientation dependent R2(*) contrast was investigated. Additionally, the effects of temperature on R2(*) and orientation dependent R2(*) contrasts were studied to understand the differences reported between a fixed specimen at room temperature and in vivo at body temperature. The results suggest that the B0 dependent R2(*) variation is better explained by the magnetic susceptibility-based model with susceptibility anisotropy. However, extracting tissue iron did not reduce the orientation dependent R2(*) contrast, suggesting iron is not the origin of the contrast. This leaves susceptibility effects from myelin as the most probable origin of the contrast. Temperature showed large contribution on both R2(*) and orientation dependent R2(*) contrasts, explaining a portion of the contrast difference between the in-vivo and in-vitro conditions.
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26
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What can we learn from T2* maps of the cortex? Neuroimage 2013; 93 Pt 2:189-200. [PMID: 23357070 DOI: 10.1016/j.neuroimage.2013.01.023] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 01/13/2013] [Accepted: 01/15/2013] [Indexed: 12/13/2022] Open
Abstract
Studies have shown that T2* contrast can reveal features of cortical anatomy. However, understanding the relationship between T2* contrast and the underlying cyto- and myelo-architecture is not an easy task, given the number of confounds, such as myelin, iron, blood vessels and structure orientation. Moreover, it is difficult to obtain reliable T2* measurements in the cortex due to its thin and folded geometry and the presence of artifacts. This review addresses issues associated with T2* mapping in the human cortex. After describing the theory behind T2* relaxation, a list of practical steps is proposed to reliably acquire and process T2* data and then map these values within the cortex using surface-based analysis. The last section addresses the question: "What can we gain from T2* cortical mapping?", with particular emphasis on Brodmann mapping.
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27
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Optimizing T1-weighted imaging of cortical myelin content at 3.0T. Neuroimage 2013; 65:1-12. [DOI: 10.1016/j.neuroimage.2012.09.051] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 09/16/2012] [Accepted: 09/18/2012] [Indexed: 11/30/2022] Open
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Hikishima K, Sawada K, Murayama A, Komaki Y, Kawai K, Sato N, Inoue T, Itoh T, Momoshima S, Iriki A, Okano H, Sasaki E, Okano H. Atlas of the developing brain of the marmoset monkey constructed using magnetic resonance histology. Neuroscience 2013; 230:102-13. [DOI: 10.1016/j.neuroscience.2012.09.053] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 08/29/2012] [Accepted: 09/22/2012] [Indexed: 10/27/2022]
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Cloutman LL, Lambon Ralph MA. Connectivity-based structural and functional parcellation of the human cortex using diffusion imaging and tractography. Front Neuroanat 2012; 6:34. [PMID: 22952459 PMCID: PMC3429885 DOI: 10.3389/fnana.2012.00034] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Accepted: 07/28/2012] [Indexed: 01/17/2023] Open
Abstract
The parcellation of the cortex via its anatomical properties has been an important research endeavor for over a century. To date, however, a universally accepted parcellation scheme for the human brain still remains elusive. In the current review, we explore the use of in vivo diffusion imaging and white matter tractography as a non-invasive method for the structural and functional parcellation of the human cerebral cortex, discussing the strengths and limitations of the current approaches. Cortical parcellation via white matter connectivity is based on the premise that, as connectional anatomy determines functional organization, it should be possible to segregate functionally-distinct cortical regions by identifying similarities and differences in connectivity profiles. Recent studies have provided initial evidence in support of the efficacy of this connectional parcellation methodology. Such investigations have identified distinct cortical subregions which correlate strongly with functional regions identified via fMRI and meta-analyses. Furthermore, a strong parallel between the cortical regions defined via tractographic and more traditional cytoarchitectonic parcellation methods has been observed. However, the degree of correspondence and relative functional importance of cytoarchitectonic- versus connectivity-derived parcellations still remains unclear. Diffusion tractography remains one of the only methods capable of visualizing the structural networks of the brain in vivo. As such, it is of vital importance to continue to improve the accuracy of the methodology and to extend its potential applications in the study of cognition in neurological health and disease.
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Affiliation(s)
- Lauren L Cloutman
- Neuroscience and Aphasia Research Unit, School of Psychological Sciences, University of Manchester Manchester, UK
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Bandettini PA, Bowtell R, Jezzard P, Turner R. Ultrahigh field systems and applications at 7 T and beyond: progress, pitfalls, and potential. Magn Reson Med 2012; 67:317-21. [PMID: 22083719 PMCID: PMC3265677 DOI: 10.1002/mrm.23151] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 07/13/2011] [Accepted: 07/22/2011] [Indexed: 11/06/2022]
Abstract
About 150 researchers around the world convened at the Chateau Lake Louise on February 20-23, 2011 to present and discuss the latest research in human and animal imaging and spectroscopy at field strengths of 7 T or above (termed ultrahigh field) at the third ISMRM-sponsored high field workshop. The clear overall message from the workshop presentations and discussion is that ultrahigh field imaging is gaining momentum with regard to new clinically relevant findings, anatomic and functional MRI results, susceptibility contrast advancements, solutions to high field-related image quality challenges, and to generally push the limits of resolution and speed of high field imaging. This meeting report is organized in a manner reflecting the meeting organization itself, covering the seven sessions that were approximately titled: (1) high field overview from head to body to spectroscopy; (2) susceptibility imaging; (3) proffered session on susceptibility, ultrafast imaging, unique contrast at 7 T, and angiography; (4) neuroscience applications; (5) proffered session on coils, shimming, parallel imaging, diffusion tensor imaging, and MRI-PET fusion; (6) high field animal imaging and spectroscopy, as well as a vendor overview, and (7) Cutting edge technology at 7 T.
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Affiliation(s)
- Peter A Bandettini
- Section on Functional Imaging Methods and Functional MRI Core Facility, National Institute of Mental Health, Bethesda, Maryland 20882, USA.
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Cohen-Adad J, Polimeni JR, Helmer KG, Benner T, McNab JA, Wald LL, Rosen BR, Mainero C. T₂* mapping and B₀ orientation-dependence at 7 T reveal cyto- and myeloarchitecture organization of the human cortex. Neuroimage 2012; 60:1006-14. [PMID: 22270354 DOI: 10.1016/j.neuroimage.2012.01.053] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 12/08/2011] [Accepted: 01/05/2012] [Indexed: 11/18/2022] Open
Abstract
Ultra-high field MRI (≥ 7 T) has recently shown great sensitivity to depict patterns of tissue microarchitecture. Moreover, recent studies have demonstrated a dependency between T₂* and orientation of white matter fibers with respect to the main magnetic field B₀. In this study we probed the potential of T₂* mapping at 7 T to provide new markers of cortical architecture. We acquired multi-echo measurements at 7 T and mapped T₂* over the entire cortex of eight healthy individuals using surface-based analysis. B₀ dependence was tested by computing the angle θ(z) between the normal of the surface and the direction of B₀, then fitting T₂*(θ(z)) using model from the literature. Average T₂* in the cortex was 32.20 +/- 1.35 ms. Patterns of lower T₂* were detected in the sensorimotor, visual and auditory cortices, likely reflecting higher myelin content. Significantly lower T₂* was detected in the left hemisphere of the auditory region (p<0.005), suggesting higher myelin content, in accordance with previous investigations. B₀ orientation dependence was detected in some areas of the cortex, the strongest being in the primary motor cortex (∆R₂*=4.10 Hz). This study demonstrates that quantitative T₂* measures at 7 T MRI can reveal patterns of cytoarchitectural organization of the human cortex in vivo and that B₀ orientation dependence can probe the coherency and orientation of gray matter fibers in the cortex, shedding light into the potential use of this type of contrast to characterize cyto-/myeloarchitecture and to understand the pathophysiology of diseases associated with changes in iron and/or myelin concentration.
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Affiliation(s)
- J Cohen-Adad
- A.A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA.
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