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Chang M, Nehs S, Xu Z, Kanold PO. Distinct distribution of subplate neuron subtypes between the sensory cortices during the early postnatal period. J Comp Neurol 2024; 532:e25594. [PMID: 38407509 PMCID: PMC11186582 DOI: 10.1002/cne.25594] [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: 07/31/2023] [Revised: 01/09/2024] [Accepted: 02/09/2024] [Indexed: 02/27/2024]
Abstract
Subplate neurons (SpNs) are a heterogeneous neuronal population actively involved in early cortical circuit formation. In rodents, many SpNs survive and form layer 6b. The molecular heterogeneity of SpNs raises the question of whether different subpopulations of SpNs survive through the early postnatal period similarly and whether such diverse SpN populations in the auditory cortex (ACtx) share a common distribution pattern with other sensory systems. To address that, we investigated the expression pattern of multiple specific SpN markers in the ACtx, as well as in the visual (VCtx) and somatosensory (SCtx) cortices as controls, using complexin 3 (Cplx3) antibodies and different SpN-specific Cre-driver mice, such as connective tissue growth factor (CTGF), dopamine receptor D1 (Drd1a), and neurexophilin 4 (Nxph4). We focused on two early time windows in auditory development: (1) during the second postnatal week (PNW) before ear-canal opening and (2) during the third PNW after ear-canal opening. We compared the expression pattern of different SpN markers in ACtx with VCtx and SCtx. At both examined timepoints, Cplx3 and Nxph4 expressing SpNs form the largest and smallest population in the ACtx, respectively. Similar distribution patterns are observable in the VCtx and SCtx during the second PNW but not during the third PNW, for a higher proportion of Drd1a expressing SpNs is detected in the VCtx and CTGF expressing SpNs in the SCtx. This study suggests that different populations of SpNs might contribute differently to the development of individual sensory circuits.
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Affiliation(s)
- Minzi Chang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Sophia Nehs
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Zheng Xu
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Patrick O Kanold
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, Maryland, USA
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2
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Feldmeyer D. Structure and function of neocortical layer 6b. Front Cell Neurosci 2023; 17:1257803. [PMID: 37744882 PMCID: PMC10516558 DOI: 10.3389/fncel.2023.1257803] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 08/14/2023] [Indexed: 09/26/2023] Open
Abstract
Cortical layer 6b is considered by many to be a remnant of the subplate that forms during early stages of neocortical development, but its role in the adult is not well understood. Its neuronal complement has only recently become the subject of systematic studies, and its axonal projections and synaptic input structures have remained largely unexplored despite decades of research into neocortical function. In recent years, however, layer 6b (L6b) has attracted increasing attention and its functional role is beginning to be elucidated. In this review, I will attempt to provide an overview of what is currently known about the excitatory and inhibitory neurons in this layer, their pre- and postsynaptic connectivity, and their functional implications. Similarities and differences between different cortical areas will be highlighted. Finally, layer 6b neurons are highly responsive to several neuropeptides such as orexin/hypocretin, neurotensin and cholecystokinin, in some cases exclusively. They are also strongly controlled by neurotransmitters such as acetylcholine and norepinephrine. The interaction of these neuromodulators with L6b microcircuitry and its functional consequences will also be discussed.
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Affiliation(s)
- Dirk Feldmeyer
- Research Centre Jülich, Institute of Neuroscience and Medicine 10 (INM-10), Jülich, Germany
- Department of Psychiatry, Psychotherapy, and Psychosomatics, RWTH Aachen University Hospital, Aachen, Germany
- Jülich-Aachen Research Alliance, Translational Brain Medicine (JARA Brain), Aachen, Germany
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3
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Gellért L, Luhmann HJ, Kilb W. Axonal connections between S1 barrel, M1, and S2 cortex in the newborn mouse. Front Neuroanat 2023; 17:1105998. [PMID: 36760662 PMCID: PMC9905141 DOI: 10.3389/fnana.2023.1105998] [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: 11/23/2022] [Accepted: 01/09/2023] [Indexed: 01/26/2023] Open
Abstract
The development of functionally interconnected networks between primary (S1), secondary somatosensory (S2), and motor (M1) cortical areas requires coherent neuronal activity via corticocortical projections. However, the anatomical substrate of functional connections between S1 and M1 or S2 during early development remains elusive. In the present study, we used ex vivo carbocyanine dye (DiI) tracing in paraformaldehyde-fixed newborn mouse brain to investigate axonal projections of neurons in different layers of S1 barrel field (S1Bf), M1, and S2 toward the subplate (SP), a hub layer for sensory information transfer in the immature cortex. In addition, we performed extracellular recordings in neocortical slices to unravel the functional connectivity between these areas. Our experiments demonstrate that already at P0 neurons from the cortical plate (CP), layer 5/6 (L5/6), and the SP of both M1 and S2 send projections through the SP of S1Bf. Reciprocally, neurons from CP to SP of S1Bf send projections through the SP of M1 and S2. Electrophysiological recordings with multi-electrode arrays in cortical slices revealed weak, but functional synaptic connections between SP and L5/6 within and between S1 and M1. An even lower functional connectivity was observed between S1 and S2. In summary, our findings demonstrate that functional connections between SP and upper cortical layers are not confined to the same cortical area, but corticocortical connection between adjacent cortical areas exist already at the day of birth. Hereby, SP can integrate early cortical activity of M1, S1, and S2 and shape the development of sensorimotor integration at an early stage.
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Mukherjee D, Kanold PO. Changing subplate circuits: Early activity dependent circuit plasticity. Front Cell Neurosci 2023; 16:1067365. [PMID: 36713777 PMCID: PMC9874351 DOI: 10.3389/fncel.2022.1067365] [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: 10/11/2022] [Accepted: 12/16/2022] [Indexed: 01/12/2023] Open
Abstract
Early neural activity in the developing sensory system comprises spontaneous bursts of patterned activity, which is fundamental for sculpting and refinement of immature cortical connections. The crude early connections that are initially refined by spontaneous activity, are further elaborated by sensory-driven activity from the periphery such that orderly and mature connections are established for the proper functioning of the cortices. Subplate neurons (SPNs) are one of the first-born mature neurons that are transiently present during early development, the period of heightened activity-dependent plasticity. SPNs are well integrated within the developing sensory cortices. Their structural and functional properties such as relative mature intrinsic membrane properties, heightened connectivity via chemical and electrical synapses, robust activation by neuromodulatory inputs-place them in an ideal position to serve as crucial elements in monitoring and regulating spontaneous endogenous network activity. Moreover, SPNs are the earliest substrates to receive early sensory-driven activity from the periphery and are involved in its modulation, amplification, and transmission before the maturation of the direct adult-like thalamocortical connectivity. Consequently, SPNs are vulnerable to sensory manipulations in the periphery. A broad range of early sensory deprivations alters SPN circuit organization and functions that might be associated with long term neurodevelopmental and psychiatric disorders. Here we provide a comprehensive overview of SPN function in activity-dependent development during early life and integrate recent findings on the impact of early sensory deprivation on SPNs that could eventually lead to neurodevelopmental disorders.
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Affiliation(s)
- Didhiti Mukherjee
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Patrick O. Kanold
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States,Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, United States,*Correspondence: Patrick O. Kanold ✉
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5
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A direct excitatory projection from entorhinal layer 6b neurons to the hippocampus contributes to spatial coding and memory. Nat Commun 2022; 13:4826. [PMID: 35974109 PMCID: PMC9381769 DOI: 10.1038/s41467-022-32559-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 08/03/2022] [Indexed: 11/08/2022] Open
Abstract
The mammalian hippocampal formation (HF) plays a key role in several higher brain functions, such as spatial coding, learning and memory. Its simple circuit architecture is often viewed as a trisynaptic loop, processing input originating from the superficial layers of the entorhinal cortex (EC) and sending it back to its deeper layers. Here, we show that excitatory neurons in layer 6b of the mouse EC project to all sub-regions comprising the HF and receive input from the CA1, thalamus and claustrum. Furthermore, their output is characterized by unique slow-decaying excitatory postsynaptic currents capable of driving plateau-like potentials in their postsynaptic targets. Optogenetic inhibition of the EC-6b pathway affects spatial coding in CA1 pyramidal neurons, while cell ablation impairs not only acquisition of new spatial memories, but also degradation of previously acquired ones. Our results provide evidence of a functional role for cortical layer 6b neurons in the adult brain.
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Urrutia-Piñones J, Morales-Moraga C, Sanguinetti-González N, Escobar AP, Chiu CQ. Long-Range GABAergic Projections of Cortical Origin in Brain Function. Front Syst Neurosci 2022; 16:841869. [PMID: 35392440 PMCID: PMC8981584 DOI: 10.3389/fnsys.2022.841869] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/10/2022] [Indexed: 12/12/2022] Open
Abstract
The study of long-range GABAergic projections has traditionally been focused on those with subcortical origin. In the last few years, cortical GABAergic neurons have been shown to not only mediate local inhibition, but also extend long-range axons to remote cortical and subcortical areas. In this review, we delineate the different types of long-range GABAergic neurons (LRGNs) that have been reported to arise from the hippocampus and neocortex, paying attention to the anatomical and functional circuits they form to understand their role in behavior. Although cortical LRGNs are similar to their interneuron and subcortical counterparts, they comprise distinct populations that show specific patterns of cortico-cortical and cortico-fugal connectivity. Functionally, cortical LRGNs likely induce timed disinhibition in target regions to synchronize network activity. Thus, LRGNs are emerging as a new element of cortical output, acting in concert with long-range excitatory projections to shape brain function in health and disease.
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Affiliation(s)
- Jocelyn Urrutia-Piñones
- Ph.D. Program in Neuroscience, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
- Facultad de Ciencias, Instituto de Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
| | - Camila Morales-Moraga
- Facultad de Ciencias, Instituto de Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Nicole Sanguinetti-González
- Ph.D. Program in Neuroscience, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
- Facultad de Ciencias, Instituto de Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
| | - Angelica P. Escobar
- Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
- Centro de Neurobiología y Fisiopatología Integrativa, Universidad de Valparaíso, Valparaíso, Chile
| | - Chiayu Q. Chiu
- Facultad de Ciencias, Instituto de Neurociencia, Universidad de Valparaíso, Valparaíso, Chile
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- *Correspondence: Chiayu Q. Chiu,
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7
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Ghezzi F, Marques-Smith A, Anastasiades PG, Lyngholm D, Vagnoni C, Rowett A, Parameswaran G, Hoerder-Suabedissen A, Nakagawa Y, Molnar Z, Butt SJ. Non-canonical role for Lpar1-EGFP subplate neurons in early postnatal mouse somatosensory cortex. eLife 2021; 10:60810. [PMID: 34251335 PMCID: PMC8294844 DOI: 10.7554/elife.60810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 07/09/2021] [Indexed: 11/13/2022] Open
Abstract
Subplate neurons (SPNs) are thought to play a role in nascent sensory processing in neocortex. To better understand how heterogeneity within this population relates to emergent function, we investigated the synaptic connectivity of Lpar1-EGFP SPNs through the first postnatal week in whisker somatosensory cortex (S1BF). These SPNs comprise of two morphological subtypes: fusiform SPNs with local axons and pyramidal SPNs with axons that extend through the marginal zone. The former receive translaminar synaptic input up until the emergence of the whisker barrels, a timepoint coincident with significant cell death. In contrast, pyramidal SPNs receive local input from the subplate at early ages but then - during the later time window - acquire input from overlying cortex. Combined electrical and optogenetic activation of thalamic afferents identified that Lpar1-EGFP SPNs receive sparse thalamic innervation. These data reveal components of the postnatal network that interpret sparse thalamic input to direct the emergent columnar structure of S1BF.
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Affiliation(s)
- Filippo Ghezzi
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, United Kingdom
| | - Andre Marques-Smith
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, United Kingdom
| | - Paul G Anastasiades
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, United Kingdom
| | - Daniel Lyngholm
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, United Kingdom
| | - Cristiana Vagnoni
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, United Kingdom
| | - Alexandra Rowett
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, United Kingdom
| | - Gokul Parameswaran
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, United Kingdom
| | - Anna Hoerder-Suabedissen
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, United Kingdom
| | - Yasushi Nakagawa
- Department of Neuroscience, University of Minnesota, Minneapolis, United States
| | - Zoltan Molnar
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, United Kingdom
| | - Simon Jb Butt
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, United Kingdom
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8
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Adult Upper Cortical Layer Specific Transcription Factor CUX2 Is Expressed in Transient Subplate and Marginal Zone Neurons of the Developing Human Brain. Cells 2021; 10:cells10020415. [PMID: 33671178 PMCID: PMC7922267 DOI: 10.3390/cells10020415] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/10/2021] [Accepted: 02/13/2021] [Indexed: 12/18/2022] Open
Abstract
Cut-Like Homeobox 2 (Cux2) is a transcription factor involved in dendrite and spine development, and synapse formation of projection neurons placed in mouse upper neocortical layers. Therefore, Cux2 is often used as an upper layer marker in the mouse brain. However, expression of its orthologue CUX2 remains unexplored in the human fetal neocortex. Here, we show that CUX2 protein is expressed in transient compartments of developing neocortical anlage during the main fetal phases of neocortical laminar development in human brain. During the early fetal phase when neurons of the upper cortical layers are still radially migrating to reach their final place in the cortical anlage, CUX2 was expressed in the marginal zone (MZ), deep cortical plate, and pre-subplate. During midgestation, CUX2 was still expressed in the migrating upper cortical neurons as well as in the subplate (SP) and MZ neurons. At the term age, CUX2 was expressed in the gyral white matter along with its expected expression in the upper layer neurons. In sum, CUX2 was expressed in migratory neurons of prospective superficial layers and in the diverse subpopulation of transient postmigratory SP and MZ neurons. Therefore, our findings indicate that CUX2 is a novel marker of distinct transient, but critical histogenetic events during corticogenesis. Given the Cux2 functions reported in animal models, our data further suggest that the expression of CUX2 in postmigratory SP and MZ neurons is associated with their unique dendritic and synaptogenesis characteristics.
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9
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Bruguier H, Suarez R, Manger P, Hoerder-Suabedissen A, Shelton AM, Oliver DK, Packer AM, Ferran JL, García-Moreno F, Puelles L, Molnár Z. In search of common developmental and evolutionary origin of the claustrum and subplate. J Comp Neurol 2020; 528:2956-2977. [PMID: 32266722 DOI: 10.1002/cne.24922] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 04/01/2020] [Accepted: 04/02/2020] [Indexed: 02/06/2023]
Abstract
The human claustrum, a major hub of widespread neocortical connections, is a thin, bilateral sheet of gray matter located between the insular cortex and the striatum. The subplate is a largely transient cortical structure that contains some of the earliest generated neurons of the cerebral cortex and has important developmental functions to establish intra- and extracortical connections. In human and macaque some subplate cells undergo regulated cell death, but some remain as interstitial white matter cells. In mouse and rat brains a compact layer is formed, Layer 6b, and it remains underneath the cortex, adjacent to the white matter. Whether Layer 6b in rodents is homologous to primate subplate or interstitial white matter cells is still debated. Gene expression patterns, such as those of Nurr1/Nr4a2, have suggested that the rodent subplate and the persistent subplate cells in Layer 6b and the claustrum might have similar origins. Moreover, the birthdates of the claustrum and Layer 6b are similarly precocious in mice. These observations prompted our speculations on the common developmental and evolutionary origin of the claustrum and the subplate. Here we systematically compare the currently available data on cytoarchitecture, evolutionary origin, gene expression, cell types, birthdates, neurogenesis, lineage and migration, circuit connectivity, and cell death of the neurons that contribute to the claustrum and subplate. Based on their similarities and differences we propose a partially common early evolutionary origin of the cells that become claustrum and subplate, a likely scenario that is shared in these cell populations across all amniotes.
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Affiliation(s)
- Hannah Bruguier
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Rodrigo Suarez
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Paul Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | | | - Andrew M Shelton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - David K Oliver
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Adam M Packer
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - José L Ferran
- Department of Human Anatomy, Medical School, University of Murcia and Murcia Arrixaca Institute for Biomedical Research, Murcia, Spain
| | - Fernando García-Moreno
- Achucarro Basque Center for Neuroscience, Zamudio, Spain.,IKERBASQUE Foundation, Bilbao, Spain
| | - Luis Puelles
- Department of Human Anatomy, Medical School, University of Murcia and Murcia Arrixaca Institute for Biomedical Research, Murcia, Spain
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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10
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Melzer S, Monyer H. Diversity and function of corticopetal and corticofugal GABAergic projection neurons. Nat Rev Neurosci 2020; 21:499-515. [PMID: 32747763 DOI: 10.1038/s41583-020-0344-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/29/2020] [Indexed: 12/27/2022]
Abstract
It is still widely thought that cortical projections to distant brain areas derive by and large from glutamatergic neurons. However, an increasing number of reports provide evidence that cortical GABAergic neurons comprise a smaller population of 'projection neurons' in addition to the well-known and much-studied interneurons. GABAergic long-range axons that derive from, or project to, cortical areas are thought to entrain distant brain areas for efficient information transfer and processing. Research conducted over the past 10 years has revealed that cortical GABAergic projection neurons are highly diverse in terms of molecular marker expression, synaptic targeting (identity of targeted cell types), activity pattern during distinct behavioural states and precise temporal recruitment relative to ongoing neuronal network oscillations. As GABAergic projection neurons connect many cortical areas unidirectionally or bidirectionally, it is safe to assume that they participate in the modulation of a whole series of behavioural and cognitive functions. We expect future research to examine how long-range GABAergic projections fine-tune activity in distinct distant networks and how their recruitment alters the behaviours that are supported by these networks.
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Affiliation(s)
- Sarah Melzer
- Department of Neurobiology, Howard Hughes Medical Institute, Harvard Medical School, Boston, USA
| | - Hannah Monyer
- Department of Clinical Neurobiology of the Medical Faculty of Heidelberg University and German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.
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11
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Kostović I. The enigmatic fetal subplate compartment forms an early tangential cortical nexus and provides the framework for construction of cortical connectivity. Prog Neurobiol 2020; 194:101883. [PMID: 32659318 DOI: 10.1016/j.pneurobio.2020.101883] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 06/05/2020] [Accepted: 07/06/2020] [Indexed: 12/19/2022]
Abstract
The most prominent transient compartment of the primate fetal cortex is the deep, cell-sparse, synapse-containing subplate compartment (SPC). The developmental role of the SPC and its extraordinary size in humans remain enigmatic. This paper evaluates evidence on the development and connectivity of the SPC and discusses its role in the pathogenesis of neurodevelopmental disorders. A synthesis of data shows that the subplate becomes a prominent compartment by its expansion from the deep cortical plate (CP), appearing well-delineated on MR scans and forming a tangential nexus across the hemisphere, consisting of an extracellular matrix, randomly distributed postmigratory neurons, multiple branches of thalamic and long corticocortical axons. The SPC generates early spontaneous non-synaptic and synaptic activity and mediates cortical response upon thalamic stimulation. The subplate nexus provides large-scale interareal connectivity possibly underlying fMR resting-state activity, before corticocortical pathways are established. In late fetal phase, when synapses appear within the CP, transient the SPC coexists with permanent circuitry. The histogenetic role of the SPC is to provide interactive milieu and capacity for guidance, sorting, "waiting" and target selection of thalamocortical and corticocortical pathways. The new evolutionary role of the SPC and its remnant white matter neurons is linked to the increasing number of associative pathways in the human neocortex. These roles attributed to the SPC are regulated using a spatiotemporal gene expression during critical periods, when pathogenic factors may disturb vulnerable circuitry of the SPC, causing neurodevelopmental cognitive circuitry disorders.
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Affiliation(s)
- Ivica Kostović
- Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Scientific Centre of Excellence for Basic, Clinical and Translational Neuroscience, Salata 12, 10000 Zagreb, Croatia.
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12
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Layer 6b Is Driven by Intracortical Long-Range Projection Neurons. Cell Rep 2020; 30:3492-3505.e5. [DOI: 10.1016/j.celrep.2020.02.044] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 09/20/2019] [Accepted: 02/10/2020] [Indexed: 01/03/2023] Open
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13
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Ratié L, Desmaris E, García-Moreno F, Hoerder-Suabedissen A, Kelman A, Theil T, Bellefroid EJ, Molnár Z. Loss of Dmrt5 Affects the Formation of the Subplate and Early Corticogenesis. Cereb Cortex 2019; 30:3296-3312. [PMID: 31845734 PMCID: PMC7197206 DOI: 10.1093/cercor/bhz310] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Dmrt5 (Dmrta2) and Dmrt3 are key regulators of cortical patterning and progenitor proliferation and differentiation. In this study, we show an altered apical to intermediate progenitor transition, with a delay in SP neurogenesis and premature birth of Ctip2+ cortical neurons in Dmrt5−/− mice. In addition to the cortical progenitors, DMRT5 protein appears present in postmitotic subplate (SP) and marginal zone neurons together with some migrating cortical neurons. We observed the altered split of preplate and the reduced SP and disturbed radial migration of cortical neurons into cortical plate in Dmrt5−/− brains and demonstrated an increase in the proportion of multipolar cells in primary neuronal cultures from Dmrt5−/− embryonic brains. Dmrt5 affects cortical development with specific time sensitivity that we described in two conditional mice with slightly different deletion time. We only observed a transient SP phenotype at E15.5, but not by E18.5 after early (Dmrt5lox/lox;Emx1Cre), but not late (Dmrt5lox/lox;NestinCre) deletion of Dmrt5. SP was less disturbed in Dmrt5lox/lox;Emx1Cre and Dmrt3−/− brains than in Dmrt5−/− and affects dorsomedial cortex more than lateral and caudal cortex. Our study demonstrates a novel function of Dmrt5 in the regulation of early SP formation and radial cortical neuron migration. Summary Statement Our study demonstrates a novel function of Dmrt5 in regulating marginal zone and subplate formation and migration of cortical neurons to cortical plate.
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Affiliation(s)
- Leslie Ratié
- ULB Neuroscience Institute, Université Libre de Bruxelles, B-6041 Gosselies, Belgium.,Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
| | - Elodie Desmaris
- ULB Neuroscience Institute, Université Libre de Bruxelles, B-6041 Gosselies, Belgium
| | - Fernando García-Moreno
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK.,Achucarro Basque Center for Neuroscience, Parque Científico UPV/EHU Edif. Sede, E-48940 Leioa, Spain.,IKERBASQUE Foundation, 48013 Bilbao, Spain
| | | | - Alexandra Kelman
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Thomas Theil
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Eric J Bellefroid
- ULB Neuroscience Institute, Université Libre de Bruxelles, B-6041 Gosselies, Belgium
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
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14
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Saleeba C, Dempsey B, Le S, Goodchild A, McMullan S. A Student's Guide to Neural Circuit Tracing. Front Neurosci 2019; 13:897. [PMID: 31507369 PMCID: PMC6718611 DOI: 10.3389/fnins.2019.00897] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 08/12/2019] [Indexed: 12/17/2022] Open
Abstract
The mammalian nervous system is comprised of a seemingly infinitely complex network of specialized synaptic connections that coordinate the flow of information through it. The field of connectomics seeks to map the structure that underlies brain function at resolutions that range from the ultrastructural, which examines the organization of individual synapses that impinge upon a neuron, to the macroscopic, which examines gross connectivity between large brain regions. At the mesoscopic level, distant and local connections between neuronal populations are identified, providing insights into circuit-level architecture. Although neural tract tracing techniques have been available to experimental neuroscientists for many decades, considerable methodological advances have been made in the last 20 years due to synergies between the fields of molecular biology, virology, microscopy, computer science and genetics. As a consequence, investigators now enjoy an unprecedented toolbox of reagents that can be directed against selected subpopulations of neurons to identify their efferent and afferent connectomes. Unfortunately, the intersectional nature of this progress presents newcomers to the field with a daunting array of technologies that have emerged from disciplines they may not be familiar with. This review outlines the current state of mesoscale connectomic approaches, from data collection to analysis, written for the novice to this field. A brief history of neuroanatomy is followed by an assessment of the techniques used by contemporary neuroscientists to resolve mesoscale organization, such as conventional and viral tracers, and methods of selecting for sub-populations of neurons. We consider some weaknesses and bottlenecks of the most widely used approaches for the analysis and dissemination of tracing data and explore the trajectories that rapidly developing neuroanatomy technologies are likely to take.
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Affiliation(s)
- Christine Saleeba
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
- The School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Bowen Dempsey
- CNRS, Hindbrain Integrative Neurobiology Laboratory, Neuroscience Paris-Saclay Institute (Neuro-PSI), Université Paris-Saclay, Gif-sur-Yvette, France
| | - Sheng Le
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Ann Goodchild
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Simon McMullan
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
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15
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Boon J, Clarke E, Kessaris N, Goffinet A, Molnár Z, Hoerder‐Suabedissen A. Long-range projections from sparse populations of GABAergic neurons in murine subplate. J Comp Neurol 2019; 527:1610-1620. [PMID: 30520039 PMCID: PMC6492162 DOI: 10.1002/cne.24592] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 11/01/2018] [Accepted: 11/17/2018] [Indexed: 02/05/2023]
Abstract
The murine subplate contains some of the earliest generated populations of neurons in the cerebral cortex, which play an important role in the maturation of cortical inhibition. Here we present multiple lines of evidence, that the subplate itself is only very sparsely populated with GABAergic neurons at postnatal day (P)8. We used three different transgenic mouse lines, each of which labels a subset of GABAergic, ganglionic eminence derived neurons. Dlx5/6-eGFP labels the most neurons in cortex (on average 11% of NEUN+ cells across all layers at P8) whereas CGE-derived Lhx6-Cre::Dlx1-Venusfl cells are the sparsest (2% of NEUN+ cells across all layers at P8). There is significant variability in the layer distribution of labeled interneurons, with Dlx5/6-eGFP and Lhx6-Cre::R26R-YFP being expressed most abundantly in Layer 5, whereas CGE-derived Lhx6-Cre::Dlx1-Venusfl cells are least abundant in that layer. All three lines label at most 3% of NEUN+ neurons in the subplate, in contrast to L5, in which up to 30% of neurons are GFP+ in Dlx5/6-eGFP. We assessed all three GABAergic populations for expression of the subplate neuron marker connective tissue growth factor (CTGF). CTGF labels up to two-thirds of NEUN+ cells in the subplate, but was never found to colocalize with labeled GABAergic neurons in any of the three transgenic strains. Despite the GABAergic neuronal population in the subplate being sparse, long-distance axonal connection tracing with carbocyanine dyes revealed that some Gad65-GFP+ subplate cells form long-range axonal projections to the internal capsule or callosum.
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Affiliation(s)
- Jacqueline Boon
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUnited Kingdom
- Hotchkiss Brain InstituteUniversity of CalgaryCalgaryAlbertaCanada
| | - Emma Clarke
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUnited Kingdom
- Royal Free London NHS Foundation TrustLondonUnited Kingdom
| | - Nicoletta Kessaris
- Wolfson Institute for Biomedical Research and Department of Cell and Developmental BiologyUniversity College LondonLondonUnited Kingdom
| | - André Goffinet
- Institute of NeuroscienceUniversité Catholique de LouvainLouvain‐la‐NeuveBelgium
| | - Zoltán Molnár
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUnited Kingdom
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16
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Tiong SYX, Oka Y, Sasaki T, Taniguchi M, Doi M, Akiyama H, Sato M. Kcnab1 Is Expressed in Subplate Neurons With Unilateral Long-Range Inter-Areal Projections. Front Neuroanat 2019; 13:39. [PMID: 31130851 PMCID: PMC6509479 DOI: 10.3389/fnana.2019.00039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 03/20/2019] [Indexed: 12/20/2022] Open
Abstract
Subplate (SP) neurons are among the earliest-born neurons in the cerebral cortex and heterogeneous in terms of gene expression. SP neurons consist mainly of projection neurons, which begin to extend their axons to specific target areas very early during development. However, the relationships between axon projection and gene expression patterns of the SP neurons, and their remnant layer 6b (L6b) neurons, are largely unknown. In this study, we analyzed the corticocortical projections of L6b/SP neurons in the mouse cortex and searched for a marker gene expressed in L6b/SP neurons that have ipsilateral inter-areal projections. Retrograde tracing experiments demonstrated that L6b/SP neurons in the primary somatosensory cortex (S1) projected to the primary motor cortex (M1) within the same cortical hemisphere at postnatal day (PD) 2 but did not show any callosal projection. This unilateral projection pattern persisted into adulthood. Our microarray analysis identified the gene encoding a β subunit of voltage-gated potassium channel (Kcnab1) as being expressed in L6b/SP. Double labeling with retrograde tracing and in situ hybridization demonstrated that Kcnab1 was expressed in the unilaterally-projecting neurons in L6b/SP. Embryonic expression was specifically detected in the SP as early as embryonic day (E) 14.5, shortly after the emergence of SP. Double immunostaining experiments revealed different degrees of co-expression of the protein product Kvβ1 with L6b/SP markers Ctgf (88%), Cplx3 (79%), and Nurr1 (58%), suggesting molecular subdivision of unilaterally-projecting L6b/SP neurons. In addition to expression in L6b/SP, scattered expression of Kcnab1 was observed during postnatal stages without layer specificity. Among splicing variants with three alternative first exons, the variant 1.1 explained all the cortical expression mentioned in this study. Together, our data suggest that L6b/SP neurons have corticocortical projections and Kcnab1 expression defines a subpopulation of L6b/SP neurons with a unilateral inter-areal projection.
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Affiliation(s)
- Sheena Yin Xin Tiong
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan.,Division of Developmental Neuroscience, Department of Child Development, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Osaka, Japan.,Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
| | - Yuichiro Oka
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan.,Division of Developmental Neuroscience, Department of Child Development, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Osaka, Japan.,Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.,Research Center for Child Mental Development, University of Fukui, Fukui, Japan
| | - Tatsuya Sasaki
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Manabu Taniguchi
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Miyuki Doi
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Hisanori Akiyama
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Makoto Sato
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan.,Division of Developmental Neuroscience, Department of Child Development, United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Osaka, Japan.,Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.,Research Center for Child Mental Development, University of Fukui, Fukui, Japan
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17
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Swiegers J, Bhagwandin A, Sherwood CC, Bertelsen MF, Maseko BC, Hemingway J, Rockland KS, Molnár Z, Manger PR. The distribution, number, and certain neurochemical identities of infracortical white matter neurons in a lar gibbon (Hylobates lar) brain. J Comp Neurol 2018; 527:1633-1653. [PMID: 30378128 DOI: 10.1002/cne.24545] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/04/2018] [Accepted: 09/21/2018] [Indexed: 01/08/2023]
Abstract
We examined the number, distribution, and immunoreactivity of the infracortical white matter neuronal population, also termed white matter interstitial cells (WMICs), in the brain of a lesser ape, the lar gibbon. Staining for neuronal nuclear marker (NeuN) revealed WMICs throughout the infracortical white matter, these cells being most numerous and dense close to cortical layer VI, decreasing significantly in density with depth in the white matter. Stereological analysis of NeuN-immunopositive cells revealed a global estimate of ~67.5 million WMICs within the infracortical white matter of the gibbon brain, indicating that the WMICs are a numerically significant population, ~2.5% of the total cortical gray matter neurons that would be estimated for a primate brain the mass of that of the lar gibbon. Immunostaining revealed subpopulations of WMICs containing neuronal nitric oxide synthase (nNOS, ~7 million in number, with both small and large soma volumes), calretinin (~8.6 million in number, all of similar soma volume), very few WMICs containing parvalbumin, and no calbindin-immunopositive neurons. These nNOS, calretinin, and parvalbumin immunopositive WMICs, presumably all inhibitory neurons, represent ~23.1% of the total WMIC population. As the white matter is affected in many cognitive conditions, such as schizophrenia, autism and also in neurodegenerative diseases, understanding these neurons across species is important for the translation of findings of neural dysfunction in animal models to humans. Furthermore, studies of WMICs in species such as apes provide a crucial phylogenetic context for understanding the evolution of these cell types in the human brain.
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Affiliation(s)
- Jordan Swiegers
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Adhil Bhagwandin
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Chet C Sherwood
- Department of Anthropology and Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, District of Columbia
| | - Mads F Bertelsen
- Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark
| | - Busisiwe C Maseko
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Jason Hemingway
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Kathleen S Rockland
- Department of Anatomy and Neurobiology, School of Medicine, Boston University, Boston, Massachusetts
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England
| | - Paul R Manger
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
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