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Horibe K, Taga G, Fujimoto K. Geodesic theory of long association fibers arrangement in the human fetal cortex. Cereb Cortex 2023; 33:9778-9786. [PMID: 37482884 PMCID: PMC10472492 DOI: 10.1093/cercor/bhad243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 06/12/2023] [Accepted: 06/13/2023] [Indexed: 07/25/2023] Open
Abstract
Association fibers connect different areas of the cerebral cortex over long distances and integrate information to achieve higher brain functions, particularly in humans. Prototyped association fibers are developed to the respective tangential direction throughout the cerebral hemispheres along the deepest border of the subplate during the fetal period. However, how guidance to remote areas is achieved is not known. Because the subplate is located below the cortical surface, the tangential direction of the fibers may be biased by the curved surface geometry due to Sylvian fissure and cortical poles. The fiber length can be minimized if the tracts follow the shortest paths (geodesics) of the curved surface. Here, we propose and examine a theory that geodesics guide the tangential direction of long association fibers by analyzing how geodesics are spatially distributed on the fetal human brains. We found that the geodesics were dense on the saddle-shaped surface of the perisylvian region and sparse on the dome-shaped cortical poles. The geodesics corresponded with the arrangement of five typical association fibers, supporting the theory. Thus, the geodesic theory provides directional guidance information for wiring remote areas and suggests that long association fibers emerge from minimizing their tangential length in fetal brains.
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Affiliation(s)
- Kazuya Horibe
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, 560-0043 Osaka, Japan
- Department of Systems Innovation, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, 560-8531 Osaka, Japan
| | - Gentaro Taga
- Department of Physical and Health Education, Graduate School of Education, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Koichi Fujimoto
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, 560-0043 Osaka, Japan
- Program of Mathematical and Life Sciences, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526 Hiroshima, Japan
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Gentle as a mother's touch: C-tactile touch promotes autonomic regulation in preterm infants. Physiol Behav 2022; 257:113991. [PMID: 36242858 DOI: 10.1016/j.physbeh.2022.113991] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/25/2022] [Accepted: 10/06/2022] [Indexed: 11/06/2022]
Abstract
Preterm infants are challenged to adapt to an extrauterine milieu, while their interoceptive system and autonomic regulation capacity is still immature. Caressing parental touch is known to foster parasympathetic regulation in infants by stimulating C-tactile (CT) afferents and in preterm infants, slow stroking stimulation also leads to a heart rate decrease. The particular impact of maternal stroking has not yet been investigated and factors influencing the maturation of the CT system in preterm infants remain unclear. We therefore analysed 53 standardized events in which preterm infants (24 to 36 weeks gestational age at birth) were stroked by their mothers. Video analysis revealed that mothers use CT optimal velocities to stroke their preterm child. Analysis of pulse oximetric data showed no effect of stroking on infantile blood oxygenation, but a significant decrease of the heart rate. Compared to term-born children, this decrease was delayed by about two minutes. Furthermore, our data suggested that more immature preterm infants benefited less from stroking than more mature ones. We conclude that maternal stroking touch targets CT afferents in preterm infants and that the preterm CT system is not yet mature.
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Tsujimura K, Shiohama T, Takahashi E. microRNA Biology on Brain Development and Neuroimaging Approach. Brain Sci 2022; 12:brainsci12101366. [PMID: 36291300 PMCID: PMC9599180 DOI: 10.3390/brainsci12101366] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/05/2022] [Accepted: 10/06/2022] [Indexed: 11/22/2022] Open
Abstract
Proper brain development requires the precise coordination and orchestration of various molecular and cellular processes and dysregulation of these processes can lead to neurological diseases. In the past decades, post-transcriptional regulation of gene expression has been shown to contribute to various aspects of brain development and function in the central nervous system. MicroRNAs (miRNAs), short non-coding RNAs, are emerging as crucial players in post-transcriptional gene regulation in a variety of tissues, such as the nervous system. In recent years, miRNAs have been implicated in multiple aspects of brain development, including neurogenesis, migration, axon and dendrite formation, and synaptogenesis. Moreover, altered expression and dysregulation of miRNAs have been linked to neurodevelopmental and psychiatric disorders. Magnetic resonance imaging (MRI) is a powerful imaging technology to obtain high-quality, detailed structural and functional information from the brains of human and animal models in a non-invasive manner. Because the spatial expression patterns of miRNAs in the brain, unlike those of DNA and RNA, remain largely unknown, a whole-brain imaging approach using MRI may be useful in revealing biological and pathological information about the brain affected by miRNAs. In this review, we highlight recent advancements in the research of miRNA-mediated modulation of neuronal processes that are important for brain development and their involvement in disease pathogenesis. Also, we overview each MRI technique, and its technological considerations, and discuss the applications of MRI techniques in miRNA research. This review aims to link miRNA biological study with MRI analytical technology and deepen our understanding of how miRNAs impact brain development and pathology of neurological diseases.
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Affiliation(s)
- Keita Tsujimura
- Department of Radiology, Harvard Medical School, Boston, MA 02115, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA
- Group of Brain Function and Development, Nagoya University Neuroscience Institute of the Graduate School of Science, Nagoya 4648602, Japan
- Research Unit for Developmental Disorders, Institute for Advanced Research, Nagoya University, Nagoya 4648602, Japan
- Correspondence: (K.T.); (E.T.)
| | - Tadashi Shiohama
- Department of Pediatrics, Chiba University Hospital, Chiba 2608677, Japan
| | - Emi Takahashi
- Department of Radiology, Harvard Medical School, Boston, MA 02115, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA
- Correspondence: (K.T.); (E.T.)
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Takahashi E, Allan N, Peres R, Ortug A, van der Kouwe AJW, Valli B, Ethier E, Levman J, Baumer N, Tsujimura K, Vargas-Maya NI, McCracken TA, Lee R, Maunakea AK. Integration of structural MRI and epigenetic analyses hint at linked cellular defects of the subventricular zone and insular cortex in autism: Findings from a case study. Front Neurosci 2022; 16:1023665. [PMID: 36817099 PMCID: PMC9935943 DOI: 10.3389/fnins.2022.1023665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 12/20/2022] [Indexed: 02/05/2023] Open
Abstract
Introduction Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social interaction, communication and repetitive, restrictive behaviors, features supported by cortical activity. Given the importance of the subventricular zone (SVZ) of the lateral ventrical to cortical development, we compared molecular, cellular, and structural differences in the SVZ and linked cortical regions in specimens of ASD cases and sex and age-matched unaffected brain. Methods We used magnetic resonance imaging (MRI) and diffusion tractography on ex vivo postmortem brain samples, which we further analyzed by Whole Genome Bisulfite Sequencing (WGBS), Flow Cytometry, and RT qPCR. Results Through MRI, we observed decreased tractography pathways from the dorsal SVZ, increased pathways from the posterior ventral SVZ to the insular cortex, and variable cortical thickness within the insular cortex in ASD diagnosed case relative to unaffected controls. Long-range tractography pathways from and to the insula were also reduced in the ASD case. FACS-based cell sorting revealed an increased population of proliferating cells in the SVZ of ASD case relative to the unaffected control. Targeted qPCR assays of SVZ tissue demonstrated significantly reduced expression levels of genes involved in differentiation and migration of neurons in ASD relative to the control counterpart. Finally, using genome-wide DNA methylation analyses, we identified 19 genes relevant to neurological development, function, and disease, 7 of which have not previously been described in ASD, that were significantly differentially methylated in autistic SVZ and insula specimens. Conclusion These findings suggest a hypothesis that epigenetic changes during neurodevelopment alter the trajectory of proliferation, migration, and differentiation in the SVZ, impacting cortical structure and function and resulting in ASD phenotypes.
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Affiliation(s)
- Emi Takahashi
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Research, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States.,Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Nina Allan
- Epigenomics Research Program, Department of Anatomy, Institute for Biogenesis Research, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawai'i at Mānoa, Honolulu, HI, United States
| | - Rafael Peres
- Epigenomics Research Program, Department of Anatomy, Institute for Biogenesis Research, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawai'i at Mānoa, Honolulu, HI, United States
| | - Alpen Ortug
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Research, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States.,Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Andre J W van der Kouwe
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Research, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States.,Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Briana Valli
- Department of Behavioral Neuroscience, Northeastern University, Boston, MA, United States
| | - Elizabeth Ethier
- Department of Behavioral Neuroscience, Northeastern University, Boston, MA, United States
| | - Jacob Levman
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Research, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States.,Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States.,Department of Mathematics, Statistics and Computer Science, St. Francis Xavier University, Antigonish, NS, Canada
| | - Nicole Baumer
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, United States
| | - Keita Tsujimura
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Research, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States.,Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Nauru Idalia Vargas-Maya
- Epigenomics Research Program, Department of Anatomy, Institute for Biogenesis Research, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawai'i at Mānoa, Honolulu, HI, United States
| | - Trevor A McCracken
- Epigenomics Research Program, Department of Anatomy, Institute for Biogenesis Research, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawai'i at Mānoa, Honolulu, HI, United States
| | - Rosa Lee
- Epigenomics Research Program, Department of Anatomy, Institute for Biogenesis Research, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawai'i at Mānoa, Honolulu, HI, United States
| | - Alika K Maunakea
- Epigenomics Research Program, Department of Anatomy, Institute for Biogenesis Research, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawai'i at Mānoa, Honolulu, HI, United States
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Lammertink F, Vinkers CH, Tataranno ML, Benders MJNL. Premature Birth and Developmental Programming: Mechanisms of Resilience and Vulnerability. Front Psychiatry 2021; 11:531571. [PMID: 33488409 PMCID: PMC7820177 DOI: 10.3389/fpsyt.2020.531571] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 12/01/2020] [Indexed: 12/14/2022] Open
Abstract
The third trimester of pregnancy represents a sensitive phase for infant brain plasticity when a series of fast-developing cellular events (synaptogenesis, neuronal migration, and myelination) regulates the development of neural circuits. Throughout this dynamic period of growth and development, the human brain is susceptible to stress. Preterm infants are born with an immature brain and are, while admitted to the neonatal intensive care unit, precociously exposed to stressful procedures. Postnatal stress may contribute to altered programming of the brain, including key systems such as the hypothalamic-pituitary-adrenal axis and the autonomic nervous system. These neurobiological systems are promising markers for the etiology of several affective and social psychopathologies. As preterm birth interferes with early development of stress-regulatory systems, early interventions might strengthen resilience factors and might help reduce the detrimental effects of chronic stress exposure. Here we will review the impact of stress following premature birth on the programming of neurobiological systems and discuss possible stress-related neural circuits and pathways involved in resilience and vulnerability. Finally, we discuss opportunities for early intervention and future studies.
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Affiliation(s)
- Femke Lammertink
- Department of Neonatology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Christiaan H. Vinkers
- Department of Psychiatry, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
- Department of Anatomy & Neurosciences, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Maria L. Tataranno
- Department of Neonatology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Manon J. N. L. Benders
- Department of Neonatology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
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Matsui TK, Tsuru Y, Kuwako KI. Challenges in Modeling Human Neural Circuit Formation via Brain Organoid Technology. Front Cell Neurosci 2020; 14:607399. [PMID: 33362473 PMCID: PMC7756199 DOI: 10.3389/fncel.2020.607399] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 11/12/2020] [Indexed: 01/12/2023] Open
Abstract
Human brain organoids are three-dimensional self-organizing tissues induced from pluripotent cells that recapitulate some aspects of early development and some of the early structure of the human brain in vitro. Brain organoids consist of neural lineage cells, such as neural stem/precursor cells, neurons, astrocytes and oligodendrocytes. Additionally, brain organoids contain fluid-filled ventricle-like structures surrounded by a ventricular/subventricular (VZ/SVZ) zone-like layer of neural stem cells (NSCs). These NSCs give rise to neurons, which form multiple outer layers. Since these structures resemble some aspects of structural arrangements in the developing human brain, organoid technology has attracted great interest in the research fields of human brain development and disease modeling. Developmental brain disorders have been intensely studied through the use of human brain organoids. Relatively early steps in human brain development, such as differentiation and migration, have also been studied. However, research on neural circuit formation with brain organoids has just recently began. In this review, we summarize the current challenges in studying neural circuit formation with organoids and discuss future perspectives.
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Affiliation(s)
- Takeshi K Matsui
- Department of Neural and Muscular Physiology, Shimane University School of Medicine, Izumo, Japan
| | - Yuichiro Tsuru
- Department of Neural and Muscular Physiology, Shimane University School of Medicine, Izumo, Japan
| | - Ken-Ichiro Kuwako
- Department of Neural and Muscular Physiology, Shimane University School of Medicine, Izumo, Japan
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7
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Charvet CJ, Das A, Song JW, Tindal-Burgess DJ, Kabaria P, Dai G, Kane T, Takahashi E. High Angular Resolution Diffusion MRI Reveals Conserved and Deviant Programs in the Paths that Guide Human Cortical Circuitry. Cereb Cortex 2020; 30:1447-1464. [PMID: 31667494 PMCID: PMC7132938 DOI: 10.1093/cercor/bhz178] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 06/13/2019] [Accepted: 07/10/2019] [Indexed: 02/07/2023] Open
Abstract
Diffusion magnetic resonance (MR) tractography represents a novel opportunity to investigate conserved and deviant developmental programs between humans and other species such as mice. To that end, we acquired high angular resolution diffusion MR scans of mice [embryonic day (E) 10.5 to postnatal week 4] and human brains [gestational week (GW) 17-30] at successive stages of fetal development to investigate potential evolutionary changes in radial organization and emerging pathways between humans and mice. We compare radial glial development as well as commissural development (e.g., corpus callosum), primarily because our findings can be integrated with previous work. We also compare corpus callosal growth trajectories across primates (i.e., humans and rhesus macaques) and rodents (i.e., mice). One major finding is that the developing cortex of humans is predominated by pathways likely associated with a radial glial organization at GW 17-20, which is not as evident in age-matched mice (E 16.5, 17.5). Another finding is that, early in development, the corpus callosum follows a similar developmental timetable in primates (i.e., macaques and humans) as in mice. However, the corpus callosum grows for an extended period of time in primates compared with rodents. Taken together, these findings highlight deviant developmental programs underlying the emergence of cortical pathways in the human brain.
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Affiliation(s)
| | - Avilash Das
- Medical Sciences in the College of Arts and Sciences, Boston University, Boston, MA 02215, USA
- Division of Newborn Medicine, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02215, USA
- Fetal-Neonatal Brain Imaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02215, USA
| | - Jae W Song
- Division of Neuroradiology, Department of Radiology, Massachusetts General Hospital, Boston, MA 02114, USA
| | | | - Priya Kabaria
- Department of Behavioral Neuroscience, Northeastern University, Boston, MA 02115, USA
| | - Guangping Dai
- Science Center, Wellesley College, Wellesley, MA 02481, USA
| | - Tara Kane
- Department of Behavioral Neuroscience, Northeastern University, Boston, MA 02115, USA
| | - Emi Takahashi
- Division of Newborn Medicine, Department of Medicine, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02215, USA
- Fetal-Neonatal Brain Imaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02215, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
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Levman J, Fang Z, Zumwalt K, Cogger L, Vasung L, MacDonald P, Lim A, Takahashi E. Asymmetric Insular Connectomics Revealed by Diffusion Magnetic Resonance Imaging Analysis of Healthy Brain Development. Brain Connect 2019; 9:2-12. [PMID: 30501515 DOI: 10.1089/brain.2018.0582] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The insula has been implicated in playing important roles in various brain functions including consciousness, homeostasis, perception, self-awareness, language processing, and interpersonal experience. Abnormalities of the insula have been observed in patients suffering from addiction, deteriorating language function, anorexia, and emotional dysregulation. We analyzed typical development of insular connections in a large-scale pediatric population using 642 magnetic resonance imaging examinations. Interpreting large quantities of acquired data is one of the major challenges in connectomics. This article focuses its analysis on the connectivity observed between the insula and many other regions throughout the brain and performs a hemispheric asymmetry analysis comparing localized connectome measurements. Results demonstrate asymmetries in the pathways connecting the insula to the superior temporal region, pars opercularis, etc. that may be representative of language lateralization in the brain. Results also demonstrate multiple fiber pathways that exhibit hemispheric dominance in tract length and an inverted hemispheric dominance in tract counts, implying the presence of asymmetric lateralization of some of the brain's insular pathways. This study illustrates the investigative potential of performing connectomics-style analyses in a clinical context across a large population of children as part of routine imaging, demonstrating the feasibility of using current technologies to perform regionally focused clinical connectivity studies.
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Affiliation(s)
- Jacob Levman
- 1 Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts.,2 Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts.,3 Department of Pediatrics, Harvard Medical School, Boston, Massachusetts.,4 Department of Mathematics, Statistics and Computer Science, St. Francis Xavier University, Antigonish, Canada
| | - Zihang Fang
- 1 Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts
| | - Katarina Zumwalt
- 5 OceanPath Fellow, Coady International Institute, St. Francis Xavier University, Antigonish, Canada
| | - Liam Cogger
- 4 Department of Mathematics, Statistics and Computer Science, St. Francis Xavier University, Antigonish, Canada
| | - Lana Vasung
- 1 Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts.,3 Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
| | - Patrick MacDonald
- 1 Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts
| | - Ashley Lim
- 1 Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts
| | - Emi Takahashi
- 1 Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts.,2 Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts.,3 Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
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Vasung L, Charvet CJ, Shiohama T, Gagoski B, Levman J, Takahashi E. Ex vivo fetal brain MRI: Recent advances, challenges, and future directions. Neuroimage 2019; 195:23-37. [PMID: 30905833 PMCID: PMC6617515 DOI: 10.1016/j.neuroimage.2019.03.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 03/12/2019] [Accepted: 03/16/2019] [Indexed: 12/21/2022] Open
Abstract
During early development, the fetal brain undergoes dynamic morphological changes. These changes result from neurogenic events, such as neuronal proliferation, migration, axonal elongation, retraction, and myelination. The duration and intensity of these events vary across species. Comparative assessments of these neurogenic events give us insight into evolutionary changes and the complexity of human brain development. Recent advances in magnetic resonance imaging (MRI), especially ex vivo MRI, permit characterizing and comparing fetal brain development across species. Comparative ex vivo MRI studies support the detection of species-specific differences that occur during early brain development. In this review, we provide a comprehensive overview of ex vivo MRI studies that characterize early brain development in humans, monkeys, cats, as well as rats/mice. Finally, we discuss the current advantages and limitations of ex vivo fetal brain MRI.
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Affiliation(s)
- Lana Vasung
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, 401 Park Dr., Boston, MA, 02215, USA
| | - Christine J Charvet
- Department of Molecular Biology and Genetics, Cornell University, 526 Campus Rd, Ithaca, NY, 14850, USA; Department of Psychology, Delaware State University, Dover, DE, 19901, USA
| | - Tadashi Shiohama
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, 401 Park Dr., Boston, MA, 02215, USA; Department of Pediatrics, Chiba University Hospital, Inohana 1-8-1, Chiba-shi, Chiba, 2608670, Japan
| | - Borjan Gagoski
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, 401 Park Dr., Boston, MA, 02215, USA
| | - Jacob Levman
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, 401 Park Dr., Boston, MA, 02215, USA; Department of Mathematics, Statistics and Computer Science, St. Francis Xavier University, Antigonish, NS, B2G 2W5, Canada
| | - Emi Takahashi
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, 401 Park Dr., Boston, MA, 02215, USA.
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Wang R, Wilkinson M, Kane T, Takahashi E. Convergence of Cortical, Thalamocortical, and Callosal Pathways during Human Fetal Development Revealed by Diffusion MRI Tractography. Front Neurosci 2017; 11:576. [PMID: 29163000 PMCID: PMC5671991 DOI: 10.3389/fnins.2017.00576] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 10/02/2017] [Indexed: 11/17/2022] Open
Abstract
There has been evidence that during brain development, emerging thalamocortical (TC) and corticothalamic (CT) pathways converge in some brain regions and follow each other's trajectories to their final destinations. Corpus callosal (CC) pathways also emerge at a similar developmental stage, and are known to converge with TC pathways in specific cortical regions in mature brains. Given the functional relationships between TC and CC pathways, anatomical convergence of the two pathways are likely important for their functional integration. However, it is unknown (1) where TC and CT subcortically converge in the human brain, and (2) where TC and CC converge in the cortex of the human brain, due to the limitations of non-invasive methods. The goals of this study were to describe the spatio-temporal relationships in the development of the TC/CT and CC pathways in the human brain, using high-angular resolution diffusion MR imaging (HARDI) tractography. Emerging cortical, TC and CC pathways were identified in postmortem fetal brains ranging from 17 gestational weeks (GW) to 30 GW, as well as in vivo 34-40 GW newborns. Some pathways from the thalami were found to be converged with pathways from the cerebral cortex as early as 17 GW. Such convergence was observed mainly in anterior and middle regions of the brain until 21 GW. At 22 GW and onwards, posterior pathways from the thalami also converged with cortical pathways. Many CC pathways reached the full length up to the cortical surface as early as 17 GW, while pathways linked to thalami (not only TC axons but also including pathways linked to thalamic neuronal migration) reached the cortical surface at and after 20 GW. These results suggest that CC pathways developed earlier than the TC pathways. The two pathways were widespread at early stages, but by 40 GW they condensed and formed groups of pathways that projected to specific regions of the cortex and overlapped in some brain regions. These results suggest that HARDI tractography has the potential to identify developing TC/CT and CC pathways with the timing and location of their convergence in fetal stages persisting in postnatal development.
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Affiliation(s)
- Rongpin Wang
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
- Department of Radiology, Guizhou Provincial People's Hospital, Guiyang, China
| | - Molly Wilkinson
- Department of Behavioral Neuroscience, Northeastern University, Boston, MA, United States
| | - Tara Kane
- Department of Behavioral Neuroscience, Northeastern University, Boston, MA, United States
| | - Emi Takahashi
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States
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