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Martinetti LE, Autio DM, Crandall SR. Motor Control of Distinct Layer 6 Corticothalamic Feedback Circuits. eNeuro 2024; 11:ENEURO.0255-24.2024. [PMID: 38926084 PMCID: PMC11236587 DOI: 10.1523/eneuro.0255-24.2024] [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: 06/11/2024] [Accepted: 06/20/2024] [Indexed: 06/28/2024] Open
Abstract
Layer 6 corticothalamic (L6 CT) neurons provide massive input to the thalamus, and these feedback connections enable the cortex to influence its own sensory input by modulating thalamic excitability. However, the functional role(s) feedback serves during sensory processing is unclear. One hypothesis is that CT feedback is under the control of extrasensory signals originating from higher-order cortical areas, yet we know nothing about the mechanisms of such control. It is also unclear whether such regulation is specific to CT neurons with distinct thalamic connectivity. Using mice (either sex) combined with in vitro electrophysiology techniques, optogenetics, and retrograde labeling, we describe studies of vibrissal primary motor cortex (vM1) influences on different CT neurons in the vibrissal primary somatosensory cortex (vS1) with distinct intrathalamic axonal projections. We found that vM1 inputs are highly selective, evoking stronger postsynaptic responses in CT neurons projecting to the dual ventral posterior medial nucleus (VPm) and posterior medial nucleus (POm) located in lower L6a than VPm-only-projecting CT cells in upper L6a. A targeted analysis of the specific cells and synapses involved revealed that the greater responsiveness of Dual CT neurons was due to their distinctive intrinsic membrane properties and synaptic mechanisms. These data demonstrate that vS1 has at least two discrete L6 CT subcircuits distinguished by their thalamic projection patterns, intrinsic physiology, and functional connectivity with vM1. Our results also provide insights into how a distinct CT subcircuit may serve specialized roles specific to contextual modulation of tactile-related sensory signals in the somatosensory thalamus during active vibrissa movements.
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Affiliation(s)
- Luis E Martinetti
- Neuroscience Program, Michigan State University, East Lansing, Michigan 48824
| | - Dawn M Autio
- Department of Physiology, Michigan State University, East Lansing, Michigan 48824
| | - Shane R Crandall
- Neuroscience Program, Michigan State University, East Lansing, Michigan 48824
- Department of Physiology, Michigan State University, East Lansing, Michigan 48824
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2
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Martinetti LE, Autio DM, Crandall SR. Motor Control of Distinct Layer 6 Corticothalamic Feedback Circuits. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.22.590613. [PMID: 38712153 PMCID: PMC11071411 DOI: 10.1101/2024.04.22.590613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Layer 6 corticothalamic (L6 CT) neurons provide massive input to the thalamus, and these feedback connections enable the cortex to influence its own sensory input by modulating thalamic excitability. However, the functional role(s) feedback serves during sensory processing is unclear. One hypothesis is that CT feedback is under the control of extra-sensory signals originating from higher-order cortical areas, yet we know nothing about the mechanisms of such control. It is also unclear whether such regulation is specific to CT neurons with distinct thalamic connectivity. Using mice (either sex) combined with in vitro electrophysiology techniques, optogenetics, and retrograde labeling, we describe studies of vibrissal primary motor cortex (vM1) influences on different CT neurons in the vibrissal primary somatosensory cortex (vS1) with distinct intrathalamic axonal projections. We found that vM1 inputs are highly selective, evoking stronger postsynaptic responses in Dual ventral posterior medial nucleus (VPm) and posterior medial nucleus (POm) projecting CT neurons located in lower L6a than VPm-only projecting CT cells in upper L6a. A targeted analysis of the specific cells and synapses involved revealed that the greater responsiveness of Dual CT neurons was due to their distinctive intrinsic membrane properties and synaptic mechanisms. These data demonstrate that vS1 has at least two discrete L6 CT subcircuits distinguished by their thalamic projection patterns, intrinsic physiology, and functional connectivity with vM1. Our results also provide insights into how a distinct CT subcircuit may serve specialized roles specific to contextual modulation of tactile-related sensory signals in the somatosensory thalamus during active vibrissa movements.
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Affiliation(s)
| | - Dawn M. Autio
- Department of Physiology, Michigan State University, East Lansing, MI 48824
| | - Shane R. Crandall
- Neuroscience Program, Michigan State University, East Lansing, MI 48824
- Department of Physiology, Michigan State University, East Lansing, MI 48824
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3
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Ding C, Yang D, Feldmeyer D. Adenosinergic Modulation of Layer 6 Microcircuitry in the Medial Prefrontal Cortex Is Specific to Presynaptic Cell Type. J Neurosci 2024; 44:e1606232023. [PMID: 38429106 PMCID: PMC11007316 DOI: 10.1523/jneurosci.1606-23.2023] [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: 08/25/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 03/03/2024] Open
Abstract
Adenosinergic modulation in the PFC is recognized for its involvement in various behavioral aspects including sleep homoeostasis, decision-making, spatial working memory and anxiety. While the principal cells of layer 6 (L6) exhibit a significant morphological diversity, the detailed cell-specific regulatory mechanisms of adenosine in L6 remain unexplored. Here, we quantitatively analyzed the morphological and electrophysiological parameters of L6 neurons in the rat medial prefrontal cortex (mPFC) using whole-cell recordings combined with morphological reconstructions. We were able to identify two different morphological categories of excitatory neurons in the mPFC of both juvenile and young adult rats with both sexes. These categories were characterized by a leading dendrite that was oriented either upright (toward the pial surface) or inverted (toward the white matter). These two excitatory neuron subtypes exhibited different electrophysiological and synaptic properties. Adenosine at a concentration of 30 µM indiscriminately suppressed connections with either an upright or an inverted presynaptic excitatory neuron. However, using lower concentrations of adenosine (10 µM) revealed that synapses originating from L6 upright neurons have a higher sensitivity to adenosine-induced inhibition of synaptic release. Adenosine receptor activation causes a reduction in the probability of presynaptic neurotransmitter release that could be abolished by specifically blocking A1 adenosine receptors (A1ARs) using 8-cyclopentyltheophylline (CPT). Our results demonstrate a differential expression level of A1ARs at presynaptic sites of two functionally and morphologically distinct subpopulations of L6 principal neurons, suggesting the intricate functional role of adenosine in neuronal signaling in the brain.
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Affiliation(s)
- Chao Ding
- Research Center Juelich, Institute of Neuroscience and Medicine 10, Research Center Juelich, Juelich 52425, Germany
| | - Danqing Yang
- Research Center Juelich, Institute of Neuroscience and Medicine 10, Research Center Juelich, Juelich 52425, Germany
- Department of Psychiatry, Psychotherapy, and Psychosomatics, RWTH Aachen University Hospital, Aachen 52074, Germany
| | - Dirk Feldmeyer
- Research Center Juelich, Institute of Neuroscience and Medicine 10, Research Center Juelich, Juelich 52425, Germany
- Department of Psychiatry, Psychotherapy, and Psychosomatics, RWTH Aachen University Hospital, Aachen 52074, Germany
- Jülich-Aachen Research Alliance, Translational Brain Medicine (JARA Brain), Aachen 52074, Germany
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4
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Zolnik TA, Bronec A, Ross A, Staab M, Sachdev RNS, Molnár Z, Eickholt BJ, Larkum ME. Layer 6b controls brain state via apical dendrites and the higher-order thalamocortical system. Neuron 2024; 112:805-820.e4. [PMID: 38101395 DOI: 10.1016/j.neuron.2023.11.021] [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: 03/10/2023] [Revised: 09/11/2023] [Accepted: 11/18/2023] [Indexed: 12/17/2023]
Abstract
The deepest layer of the cortex (layer 6b [L6b]) contains relatively few neurons, but it is the only cortical layer responsive to the potent wake-promoting neuropeptide orexin/hypocretin. Can these few neurons significantly influence brain state? Here, we show that L6b-photoactivation causes a surprisingly robust enhancement of attention-associated high-gamma oscillations and population spiking while abolishing slow waves in sleep-deprived mice. To explain this powerful impact on brain state, we investigated L6b's synaptic output using optogenetics, electrophysiology, and monoCaTChR ex vivo. We found powerful output in the higher-order thalamus and apical dendrites of L5 pyramidal neurons, via L1a and L5a, as well as in superior colliculus and L6 interneurons. L6b subpopulations with distinct morphologies and short- and long-term plasticities project to these diverse targets. The L1a-targeting subpopulation triggered powerful NMDA-receptor-dependent spikes that elicited burst firing in L5. We conclude that orexin/hypocretin-activated cortical neurons form a multifaceted, fine-tuned circuit for the sustained control of the higher-order thalamocortical system.
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Affiliation(s)
- Timothy Adam Zolnik
- Department of Biochemistry, Charité Universitätsmedizin Berlin, Berlin 10117, Germany; Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany.
| | - Anna Bronec
- Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany
| | - Annemarie Ross
- Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany
| | - Marcel Staab
- Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany
| | - Robert N S Sachdev
- Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany
| | - Zoltán Molnár
- Department of Biochemistry, Charité Universitätsmedizin Berlin, Berlin 10117, Germany; Department of Physiology, Anatomy, and Genetics, University of Oxford, Parks Road, Sherrington Building, Oxford OX1 3PT, UK
| | | | - Matthew Evan Larkum
- Department of Biology, Humboldt Universität zu Berlin, Berlin 10117, Germany.
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5
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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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6
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Han C, English G, Saal HP, Indiveri G, Gilra A, von der Behrens W, Vasilaki E. Modelling novelty detection in the thalamocortical loop. PLoS Comput Biol 2023; 19:e1009616. [PMID: 37186588 DOI: 10.1371/journal.pcbi.1009616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 05/25/2023] [Accepted: 02/21/2023] [Indexed: 05/17/2023] Open
Abstract
In complex natural environments, sensory systems are constantly exposed to a large stream of inputs. Novel or rare stimuli, which are often associated with behaviorally important events, are typically processed differently than the steady sensory background, which has less relevance. Neural signatures of such differential processing, commonly referred to as novelty detection, have been identified on the level of EEG recordings as mismatch negativity (MMN) and on the level of single neurons as stimulus-specific adaptation (SSA). Here, we propose a multi-scale recurrent network with synaptic depression to explain how novelty detection can arise in the whisker-related part of the somatosensory thalamocortical loop. The "minimalistic" architecture and dynamics of the model presume that neurons in cortical layer 6 adapt, via synaptic depression, specifically to a frequently presented stimulus, resulting in reduced population activity in the corresponding cortical column when compared with the population activity evoked by a rare stimulus. This difference in population activity is then projected from the cortex to the thalamus and amplified through the interaction between neurons of the primary and reticular nuclei of the thalamus, resulting in rhythmic oscillations. These differentially activated thalamic oscillations are forwarded to cortical layer 4 as a late secondary response that is specific to rare stimuli that violate a particular stimulus pattern. Model results show a strong analogy between this late single neuron activity and EEG-based mismatch negativity in terms of their common sensitivity to presentation context and timescales of response latency, as observed experimentally. Our results indicate that adaptation in L6 can establish the thalamocortical dynamics that produce signatures of SSA and MMN and suggest a mechanistic model of novelty detection that could generalize to other sensory modalities.
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Affiliation(s)
- Chao Han
- Department of Computer Science, University of Sheffield, Sheffield, United Kingdom
| | - Gwendolyn English
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Switzerland
- ZNZ Neuroscience Center Zurich, ETH Zurich & University of Zurich, Switzerland
| | - Hannes P Saal
- Department of Psychology, University of Sheffield, Sheffield, United Kingdom
| | - Giacomo Indiveri
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Switzerland
- ZNZ Neuroscience Center Zurich, ETH Zurich & University of Zurich, Switzerland
| | - Aditya Gilra
- Department of Computer Science, University of Sheffield, Sheffield, United Kingdom
- Machine Learning Group, Centrum Wiskunde & Informatica, Amsterdam, The Netherlands
| | - Wolfger von der Behrens
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Switzerland
- ZNZ Neuroscience Center Zurich, ETH Zurich & University of Zurich, Switzerland
| | - Eleni Vasilaki
- Department of Computer Science, University of Sheffield, Sheffield, United Kingdom
- Institute of Neuroinformatics, ETH Zurich & University of Zurich, Switzerland
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7
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Rollenhagen A, Anstötz M, Zimmermann K, Kasugai Y, Sätzler K, Molnar E, Ferraguti F, Lübke JHR. Layer-specific distribution and expression pattern of AMPA- and NMDA-type glutamate receptors in the barrel field of the adult rat somatosensory cortex: a quantitative electron microscopic analysis. Cereb Cortex 2023; 33:2342-2360. [PMID: 35732315 PMCID: PMC9977369 DOI: 10.1093/cercor/bhac212] [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: 12/09/2021] [Revised: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 11/14/2022] Open
Abstract
AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) and NMDA (N-methyl-d-aspartate) glutamate receptors are driving forces for synaptic transmission and plasticity at neocortical synapses. However, their distribution pattern in the adult rat neocortex is largely unknown and was quantified using freeze fracture replication combined with postimmunogold-labeling. Both receptors were co-localized at layer (L)4 and L5 postsynaptic densities (PSDs). At L4 dendritic shaft and spine PSDs, the number of gold grains detecting AMPA was similar, whereas at L5 shaft PSDs AMPA-receptors outnumbered those on spine PSDs. Their number was significantly higher at L5 vs. L4 PSDs. At L4 and L5 dendritic shaft PSDs, the number of gold grains detecting GluN1 was ~2-fold higher than at spine PSDs. The number of gold grains detecting the GluN1-subunit was higher for both shaft and spine PSDs in L5 vs. L4. Both receptors showed a large variability in L4 and L5. A high correlation between the number of gold grains and PSD size for both receptors and targets was observed. Both receptors were distributed over the entire PSD but showed a layer- and target-specific distribution pattern. The layer- and target-specific distribution of AMPA and GluN1 glutamate receptors partially contribute to the observed functional differences in synaptic transmission and plasticity in the neocortex.
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Affiliation(s)
- Astrid Rollenhagen
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo Brandt Str., Jülich 52425, Germany
| | - Max Anstötz
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo Brandt Str., Jülich 52425, Germany.,Institute of Anatomy II, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University, Universitätsstr. 1, Düsseldorf 40001, Germany
| | - Kerstin Zimmermann
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo Brandt Str., Jülich 52425, Germany
| | - Yu Kasugai
- Department of Pharmacology, Medical University of Innsbruck, Peter Mayr Strasse 1a, Innsbruck A-6020, Austria
| | - Kurt Sätzler
- School of Biomedical Sciences, University of Ulster, Cromore Rd., Londonderry BT52 1SA, United Kingdom
| | - Elek Molnar
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - Francesco Ferraguti
- Department of Pharmacology, Medical University of Innsbruck, Peter Mayr Strasse 1a, Innsbruck A-6020, Austria
| | - Joachim H R Lübke
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo Brandt Str., Jülich 52425, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH/Medical University Aachen, Pauwelstr. 30, Aachen 52074, Germany.,JARA Translational Medicine Jülich/Aachen, Germany
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8
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Ciganok-Hückels N, Jehasse K, Kricsfalussy-Hrabár L, Ritter M, Rüland T, Kampa BM. Postnatal development of electrophysiological and morphological properties in layer 2/3 and layer 5 pyramidal neurons in the mouse primary visual cortex. Cereb Cortex 2022; 33:5875-5884. [PMID: 36453454 PMCID: PMC10183751 DOI: 10.1093/cercor/bhac467] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 11/04/2022] [Accepted: 11/05/2022] [Indexed: 12/03/2022] Open
Abstract
Abstract
Eye-opening is a critical point for laminar maturation of pyramidal neurons (PNs) in primary visual cortex. Knowing both the intrinsic properties and morphology of PNs from the visual cortex during development is crucial to contextualize the integration of visual inputs at different age stages. Few studies have reported changes in intrinsic excitability in these neurons but were restricted to only one layer or one stage of cortical development. Here, we used in vitro whole-cell patch-clamp to investigate the developmental impact on electrophysiological properties of layer 2/3 and layer 5 PNs in mouse visual cortex. Additionally, we evaluated the morphological changes before and after eye-opening and compared these in adult mice. Overall, we found a decrease in intrinsic excitability in both layers after eye-opening which remained stable between juvenile and adult mice. The basal dendritic length increased in layer 5 neurons, whereas spine density increased in layer 2/3 neurons after eye-opening. These data show increased number of synapses after onset of sensory input paralleled with a reduced excitability, presumably as homeostatic mechanism. Altogether, we provide a database of the properties of PNs in mouse visual cortex by considering the layer- and time-specific changes of these neurons during sensory development.
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Affiliation(s)
- Natalja Ciganok-Hückels
- Systems Neurophysiology, Institute of Zoology, RWTH Aachen University , 52074 Aachen , Germany
- Research Training Group 2416 MultiSenses-MultiScales, RWTH Aachen University , 52074 Aachen , Germany
| | - Kevin Jehasse
- Systems Neurophysiology, Institute of Zoology, RWTH Aachen University , 52074 Aachen , Germany
| | | | - Mira Ritter
- Systems Neurophysiology, Institute of Zoology, RWTH Aachen University , 52074 Aachen , Germany
| | - Thomas Rüland
- Systems Neurophysiology, Institute of Zoology, RWTH Aachen University , 52074 Aachen , Germany
- Research Training Group 2416 MultiSenses-MultiScales, RWTH Aachen University , 52074 Aachen , Germany
- Institute for Biological Information Processing (IBI-1), Forschungszentrum Jülich , 52428 Jülich , Germany
| | - Björn M Kampa
- Systems Neurophysiology, Institute of Zoology, RWTH Aachen University , 52074 Aachen , Germany
- Research Training Group 2416 MultiSenses-MultiScales, RWTH Aachen University , 52074 Aachen , Germany
- JARA BRAIN, Institute of Neuroscience and Medicine (INM-10), Forschungszentrum Jülich , 52428 Jülich , Germany
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9
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Srivastava M, Angel C, Kisvárday RE, Kocsis Z, Stelescu A, Talapka P, Kisvárday Z. Form, synapses and orientation topography of a new cell type in layer 6 of the cat’s primary visual cortex. Sci Rep 2022; 12:15428. [PMID: 36104476 PMCID: PMC9474457 DOI: 10.1038/s41598-022-19746-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 09/02/2022] [Indexed: 11/19/2022] Open
Abstract
Here we report the morpho-functional features of a novel type of deep-layer neuron. The neuron was selected from a large pool of intracellularly labelled cells based on the large cell body, numerous spine-free dendrites with an overall interneuron morphology. However, the axon gave off long-range axons up to 2.8 mm from the parent soma in layers 5/6 before entering the white matter. The boutons were uniformly distributed along the axon without forming distinct clusters. Dendritic length, surface area and volume values were at least 3 times larger than any known cortical neuron types with the exception of giant pyramidal cells of layer 5. Electron microscopy of the boutons revealed that they targeted dendritic spines (78%) and less frequently dendritic shafts (22%). Nearly half of the postsynaptic dendrites were immunopositive to GABA. Superimposing the axonal field on the orientation map obtained with optical imaging showed a preponderance of boutons to cross-orientations (38%) and an equal representation of iso- and oblique orientations (31%). The results suggest an integrating role for the layer 6 stellate neuron which projects to a functionally broad range of neurons in the deep cortical layers and to other cortical and/or subcortical regions.
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10
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Ben-Simon Y, Kaefer K, Velicky P, Csicsvari J, Danzl JG, Jonas P. 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] [Key Words] [MESH Headings] [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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Affiliation(s)
- Yoav Ben-Simon
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria.
- Department of Neurophysiology and Pharmacology, Vienna Medical University, Vienna, Austria.
| | - Karola Kaefer
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
- Department of Neuroinformatics, Radboud University, Nijmegen, The Netherlands
| | - Philipp Velicky
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Jozsef Csicsvari
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Johann G Danzl
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Peter Jonas
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
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11
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Computational synthesis of cortical dendritic morphologies. Cell Rep 2022; 39:110586. [PMID: 35385736 DOI: 10.1016/j.celrep.2022.110586] [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: 04/15/2021] [Revised: 07/22/2021] [Accepted: 03/08/2022] [Indexed: 12/30/2022] Open
Abstract
Neuronal morphologies provide the foundation for the electrical behavior of neurons, the connectomes they form, and the dynamical properties of the brain. Comprehensive neuron models are essential for defining cell types, discerning their functional roles, and investigating brain-disease-related dendritic alterations. However, a lack of understanding of the principles underlying neuron morphologies has hindered attempts to computationally synthesize morphologies for decades. We introduce a synthesis algorithm based on a topological descriptor of neurons, which enables the rapid digital reconstruction of entire brain regions from few reference cells. This topology-guided synthesis generates dendrites that are statistically similar to biological reconstructions in terms of morpho-electrical and connectivity properties and offers a significant opportunity to investigate the links between neuronal morphology and brain function across different spatiotemporal scales. Synthesized cortical networks based on structurally altered dendrites associated with diverse brain pathologies revealed principles linking branching properties to the structure of large-scale networks.
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12
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Breuer TM, Krieger P. Sensory deprivation leads to subpopulation-specific changes in layer 6 corticothalamic cells. Eur J Neurosci 2021; 55:566-588. [PMID: 34927292 DOI: 10.1111/ejn.15572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 12/12/2021] [Accepted: 12/14/2021] [Indexed: 12/01/2022]
Abstract
The effect of sensory deprivation on anatomical and physiological properties in two genetically defined types of layer 6 corticothalamic pyramidal cells in mouse somatosensory barrel cortex was investigated using in vitro electrophysiology. The two types analysed were the L6-Ntsr1 subtype, found preferentially in the upper region of layer 6 and projecting to both ventral posterior medial nucleus of the thalamus and posterior medial nucleus of the thalamus, and the L6-Drd1a subtype, located mostly in the lower regions of layer 6 and projecting to posterior medial nucleus. We found that the apical dendrite in L6-Ntsr1 cells is longer and more branched, compared to L6-Drd1a cells, and that the increase in firing frequency with increasing current stimulation is steeper in L6-Drd1a cells. Sensory deprivation was achieved clipping one row of whiskers from birth until the day of experiment (16 ± 2 days). Mice of this age are actively exploring. In L6-Ntsr1, but not in L6-Drd1a cells, sensory deprivation decreased apical and basal dendrite outgrowth, and calcium influx evoked by backpropagating action potentials. These results contribute to the ongoing functional characterisation of corticothalamic layer 6 cells and indicate differences in the postnatal cortical refinement of two distinct corticothalamic circuits.
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Affiliation(s)
| | - Patrik Krieger
- Department of Systems Neuroscience, Faculty of Medicine; Ruhr University Bochum, Germany
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13
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Patel AV, Codeluppi SA, Ervin KSJ, St-Denis MB, Choleris E, Bailey CDC. Developmental Age and Biological Sex Influence Muscarinic Receptor Function and Neuron Morphology within Layer VI of the Medial Prefrontal Cortex. Cereb Cortex 2021; 32:3137-3158. [PMID: 34864929 DOI: 10.1093/cercor/bhab406] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 01/15/2023] Open
Abstract
Acetylcholine (ACh) neurotransmission within the medial prefrontal cortex (mPFC) plays an important modulatory role to support mPFC-dependent cognitive functions. This role is mediated by ACh activation of its nicotinic (nAChR) and muscarinic (mAChR) classes of receptors, which are both present on mPFC layer VI pyramidal neurons. While the expression and function of nAChRs have been characterized thoroughly for rodent mPFC layer VI neurons during postnatal development, mAChRs have not been characterized in detail. We employed whole-cell electrophysiology with biocytin filling to demonstrate that mAChR function is greater during the juvenile period of development than in adulthood for both sexes. Pharmacological experiments suggest that each of the M1, M2, and M3 mAChR subtypes contributes to ACh responses in these neurons in a sex-dependent manner. Analysis of dendrite morphology identified effects of age more often in males, as the amount of dendrite matter was greatest during the juvenile period. Interestingly, a number of positive correlations were identified between the magnitude of ACh/mAChR responses and dendrite morphology in juvenile mice that were not present in adulthood. To our knowledge, this work describes the first detailed characterization of mAChR function and its correlation with neuron morphology within layer VI of the mPFC.
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Affiliation(s)
- Ashutosh V Patel
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Sierra A Codeluppi
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Kelsy S J Ervin
- Department of Psychology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Myles B St-Denis
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Elena Choleris
- Department of Psychology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Craig D C Bailey
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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14
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Yang D, Qi G, Ding C, Feldmeyer D. Layer 6A Pyramidal Cell Subtypes Form Synaptic Microcircuits with Distinct Functional and Structural Properties. Cereb Cortex 2021; 32:2095-2111. [PMID: 34628499 PMCID: PMC9113278 DOI: 10.1093/cercor/bhab340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 08/03/2021] [Accepted: 08/25/2021] [Indexed: 11/27/2022] Open
Abstract
Neocortical layer 6 plays a crucial role in sensorimotor co-ordination and integration through functionally segregated circuits linking intracortical and subcortical areas. We performed whole-cell recordings combined with morphological reconstructions to identify morpho-electric types of layer 6A pyramidal cells (PCs) in rat barrel cortex. Cortico-thalamic (CT), cortico-cortical (CC), and cortico-claustral (CCla) PCs were classified based on their distinct morphologies and have been shown to exhibit different electrophysiological properties. We demonstrate that these three types of layer 6A PCs innervate neighboring excitatory neurons with distinct synaptic properties: CT PCs establish weak facilitating synapses onto other L6A PCs; CC PCs form synapses of moderate efficacy, while synapses made by putative CCla PCs display the highest release probability and a marked short-term depression. For excitatory-inhibitory synaptic connections in layer 6, both the presynaptic PC type and the postsynaptic interneuron type govern the dynamic properties of the respective synaptic connections. We have identified a functional division of local layer 6A excitatory microcircuits which may be responsible for the differential temporal engagement of layer 6 feed-forward and feedback networks. Our results provide a basis for further investigations on the long-range CC, CT, and CCla pathways.
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Affiliation(s)
- Danqing Yang
- Research Center Juelich, Institute of Neuroscience and Medicine 10, 52425 Juelich, Germany
| | - Guanxiao Qi
- Research Center Juelich, Institute of Neuroscience and Medicine 10, 52425 Juelich, Germany
| | - Chao Ding
- Research Center Juelich, Institute of Neuroscience and Medicine 10, 52425 Juelich, Germany
| | - Dirk Feldmeyer
- Research Center Juelich, Institute of Neuroscience and Medicine 10, 52425 Juelich, Germany.,RWTH Aachen University Hospital, Dept of Psychiatry, Psychotherapy, and Psychosomatics, 52074 Aachen, Germany.,Jülich-Aachen Research Alliance, Translational Brain Medicine (JARA Brain), Aachen, Germany
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15
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Scala F, Kobak D, Bernabucci M, Bernaerts Y, Cadwell CR, Castro JR, Hartmanis L, Jiang X, Laturnus S, Miranda E, Mulherkar S, Tan ZH, Yao Z, Zeng H, Sandberg R, Berens P, Tolias AS. Phenotypic variation of transcriptomic cell types in mouse motor cortex. Nature 2021; 598:144-150. [PMID: 33184512 PMCID: PMC8113357 DOI: 10.1038/s41586-020-2907-3] [Citation(s) in RCA: 166] [Impact Index Per Article: 55.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 10/16/2020] [Indexed: 12/13/2022]
Abstract
Cortical neurons exhibit extreme diversity in gene expression as well as in morphological and electrophysiological properties1,2. Most existing neural taxonomies are based on either transcriptomic3,4 or morpho-electric5,6 criteria, as it has been technically challenging to study both aspects of neuronal diversity in the same set of cells7. Here we used Patch-seq8 to combine patch-clamp recording, biocytin staining, and single-cell RNA sequencing of more than 1,300 neurons in adult mouse primary motor cortex, providing a morpho-electric annotation of almost all transcriptomically defined neural cell types. We found that, although broad families of transcriptomic types (those expressing Vip, Pvalb, Sst and so on) had distinct and essentially non-overlapping morpho-electric phenotypes, individual transcriptomic types within the same family were not well separated in the morpho-electric space. Instead, there was a continuum of variability in morphology and electrophysiology, with neighbouring transcriptomic cell types showing similar morpho-electric features, often without clear boundaries between them. Our results suggest that neuronal types in the neocortex do not always form discrete entities. Instead, neurons form a hierarchy that consists of distinct non-overlapping branches at the level of families, but can form continuous and correlated transcriptomic and morpho-electrical landscapes within families.
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Affiliation(s)
- Federico Scala
- Center for Neuroscience and Artificial Intelligence, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Dmitry Kobak
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Matteo Bernabucci
- Center for Neuroscience and Artificial Intelligence, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Yves Bernaerts
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
- International Max Planck Research School for Intelligent Systems, Tübingen, Germany
| | - Cathryn René Cadwell
- Department of Pathology, University of California San Francisco, San Francisco, CA, USA
| | - Jesus Ramon Castro
- Center for Neuroscience and Artificial Intelligence, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Leonard Hartmanis
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Xiaolong Jiang
- Center for Neuroscience and Artificial Intelligence, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, TX, USA
| | - Sophie Laturnus
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Elanine Miranda
- Center for Neuroscience and Artificial Intelligence, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Zheng Huan Tan
- Center for Neuroscience and Artificial Intelligence, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Zizhen Yao
- Allen Institute for Brain Science, Seattle, WA, USA
| | - Hongkui Zeng
- Allen Institute for Brain Science, Seattle, WA, USA
| | - Rickard Sandberg
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Philipp Berens
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.
- Center for Integrative Neuroscience, University of Tübingen, Tübingen, Germany.
- Institute for Bioinformatics and Medical Informatics, University of Tübingen, Tübingen, Germany.
- Bernstein Center for Computational Neuroscience, University of Tübingen, Tübingen, Germany.
| | - Andreas S Tolias
- Center for Neuroscience and Artificial Intelligence, Baylor College of Medicine, Houston, TX, USA.
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.
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16
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Schmuhl-Giesen S, Rollenhagen A, Walkenfort B, Yakoubi R, Sätzler K, Miller D, von Lehe M, Hasenberg M, Lübke JHR. Sublamina-Specific Dynamics and Ultrastructural Heterogeneity of Layer 6 Excitatory Synaptic Boutons in the Adult Human Temporal Lobe Neocortex. Cereb Cortex 2021; 32:1840-1865. [PMID: 34530440 PMCID: PMC9070345 DOI: 10.1093/cercor/bhab315] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Synapses “govern” the computational properties of any given network in the brain. However, their detailed quantitative morphology is still rather unknown, particularly in humans. Quantitative 3D-models of synaptic boutons (SBs) in layer (L)6a and L6b of the temporal lobe neocortex (TLN) were generated from biopsy samples after epilepsy surgery using fine-scale transmission electron microscopy, 3D-volume reconstructions and electron microscopic tomography. Beside the overall geometry of SBs, the size of active zones (AZs) and that of the three pools of synaptic vesicles (SVs) were quantified. SBs in L6 of the TLN were middle-sized (~5 μm2), the majority contained only a single but comparatively large AZ (~0.20 μm2). SBs had a total pool of ~1100 SVs with comparatively large readily releasable (RRP, ~10 SVs L6a), (RRP, ~15 SVs L6b), recycling (RP, ~150 SVs), and resting (~900 SVs) pools. All pools showed a remarkably large variability suggesting a strong modulation of short-term synaptic plasticity. In conclusion, L6 SBs are highly reliable in synaptic transmission within the L6 network in the TLN and may act as “amplifiers,” “integrators” but also as “discriminators” for columnar specific, long-range extracortical and cortico-thalamic signals from the sensory periphery.
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Affiliation(s)
| | - Astrid Rollenhagen
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, 52425, Jülich, Germany
| | - Bernd Walkenfort
- Imaging Center Essen (IMCES), Electron Microscopy Unit (EMU), Medical Faculty of the University of Duisburg-Essen, 45147, Essen, Germany
| | - Rachida Yakoubi
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, 52425, Jülich, Germany
| | - Kurt Sätzler
- School of Biomedical Sciences, University of Ulster, Londonderry, BT52 1SA, UK
| | - Dorothea Miller
- University Hospital/Knappschaftskrankenhaus Bochum, 44892, Bochum, Germany
| | - Marec von Lehe
- Department of Neurosurgery, Brandenburg Medical School, Ruppiner Clinics, 16816, Neuruppin, Germany
| | - Mike Hasenberg
- Imaging Center Essen (IMCES), Electron Microscopy Unit (EMU), Medical Faculty of the University of Duisburg-Essen, 45147, Essen, Germany
| | - Joachim H R Lübke
- Address correspondence to Joachim Lübke, Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, 52425 Jülich, Germany.
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17
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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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18
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Development of Auditory Cortex Circuits. J Assoc Res Otolaryngol 2021; 22:237-259. [PMID: 33909161 DOI: 10.1007/s10162-021-00794-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 03/03/2021] [Indexed: 02/03/2023] Open
Abstract
The ability to process and perceive sensory stimuli is an essential function for animals. Among the sensory modalities, audition is crucial for communication, pleasure, care for the young, and perceiving threats. The auditory cortex (ACtx) is a key sound processing region that combines ascending signals from the auditory periphery and inputs from other sensory and non-sensory regions. The development of ACtx is a protracted process starting prenatally and requires the complex interplay of molecular programs, spontaneous activity, and sensory experience. Here, we review the development of thalamic and cortical auditory circuits during pre- and early post-natal periods.
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19
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Burns TF, Rajan R. Sensing and processing whisker deflections in rodents. PeerJ 2021; 9:e10730. [PMID: 33665005 PMCID: PMC7906041 DOI: 10.7717/peerj.10730] [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: 10/23/2019] [Accepted: 12/17/2020] [Indexed: 11/20/2022] Open
Abstract
The classical view of sensory information mainly flowing into barrel cortex at layer IV, moving up for complex feature processing and lateral interactions in layers II and III, then down to layers V and VI for output and corticothalamic feedback is becoming increasingly undermined by new evidence. We review the neurophysiology of sensing and processing whisker deflections, emphasizing the general processing and organisational principles present along the entire sensory pathway—from the site of physical deflection at the whiskers to the encoding of deflections in the barrel cortex. Many of these principles support the classical view. However, we also highlight the growing number of exceptions to these general principles, which complexify the system and which investigators should be mindful of when interpreting their results. We identify gaps in the literature for experimentalists and theorists to investigate, not just to better understand whisker sensation but also to better understand sensory and cortical processing.
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Affiliation(s)
- Thomas F Burns
- Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Ramesh Rajan
- Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
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20
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Ding C, Emmenegger V, Schaffrath K, Feldmeyer D. Layer-Specific Inhibitory Microcircuits of Layer 6 Interneurons in Rat Prefrontal Cortex. Cereb Cortex 2021; 31:32-47. [PMID: 32829414 PMCID: PMC7727376 DOI: 10.1093/cercor/bhaa201] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 06/06/2020] [Accepted: 07/02/2020] [Indexed: 12/15/2022] Open
Abstract
GABAergic interneurons in different cortical areas play important roles in diverse higher-order cognitive functions. The heterogeneity of interneurons is well characterized in different sensory cortices, in particular in primary somatosensory and visual cortex. However, the structural and functional properties of the medial prefrontal cortex (mPFC) interneurons have received less attention. In this study, a cluster analysis based on axonal projection patterns revealed four distinct clusters of L6 interneurons in rat mPFC: Cluster 1 interneurons showed axonal projections similar to Martinotti-like cells extending to layer 1, cluster 2 displayed translaminar projections mostly to layer 5, and cluster 3 interneuron axons were confined to the layer 6, whereas those of cluster 4 interneurons extend also into the white matter. Correlations were found between neuron location and axonal distribution in all clusters. Moreover, all cluster 1 L6 interneurons showed a monotonically adapting firing pattern with an initial high-frequency burst. All cluster 2 interneurons were fast-spiking, while neurons in cluster 3 and 4 showed heterogeneous firing patterns. Our data suggest that L6 interneurons that have distinct morphological and physiological characteristics are likely to innervate different targets in mPFC and thus play differential roles in the L6 microcircuitry and in mPFC-associated functions.
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Affiliation(s)
- Chao Ding
- Institute of Neuroscience and Medicine, INM-10 Function of Cortical Microcircuits Group, Research Centre Jülich, 52425 Jülich, Germany
| | - Vishalini Emmenegger
- Institute of Neuroscience and Medicine, INM-10 Function of Cortical Microcircuits Group, Research Centre Jülich, 52425 Jülich, Germany
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Kim Schaffrath
- Institute of Neuroscience and Medicine, INM-10 Function of Cortical Microcircuits Group, Research Centre Jülich, 52425 Jülich, Germany
- Department of Ophthalmology, RWTH Aachen University Hospital, Medical School, 52074 Aachen, Germany
| | - Dirk Feldmeyer
- Institute of Neuroscience and Medicine, INM-10 Function of Cortical Microcircuits Group, Research Centre Jülich, 52425 Jülich, Germany
- Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University Hospital, 52074 Aachen, Germany
- JARA-Translational Brain Medicine, 52074 Aachen, Germany
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21
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Tsai SH, Tsao CY, Lee LJ. Altered White Matter and Layer VIb Neurons in Heterozygous Disc1 Mutant, a Mouse Model of Schizophrenia. Front Neuroanat 2020; 14:605029. [PMID: 33384588 PMCID: PMC7769951 DOI: 10.3389/fnana.2020.605029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/24/2020] [Indexed: 11/13/2022] Open
Abstract
Increased white matter neuron density has been associated with neuropsychiatric disorders including schizophrenia. However, the pathogenic features of these neurons are still largely unknown. Subplate neurons, the earliest generated neurons in the developing cortex have also been associated with schizophrenia and autism. The link between these neurons and mental disorders is also not well established. Since cortical layer VIb neurons are believed to be the remnant of subplate neurons in the adult rodent brain, in this study, we aimed to examine the cytoarchitecture of neurons in cortical layer VIb and the underlying white matter in heterozygous Disc1 mutant (Het) mice, a mouse model of schizophrenia. In the white matter, the number of NeuN-positive neurons was quite low in the external capsule; however, the density of these cells was found increased (54%) in Het mice compared with wildtype (WT) littermates. The density of PV-positive neurons was unchanged in the mutants. In the cortical layer VIb, the density of CTGF-positive neurons increased (21.5%) in Het mice, whereas the number of Cplx3-positive cells reduced (16.1%) in these mutants, compared with WT mice. Layer VIb neurons can be classified by their morphological characters. The morphology of Type I pyramidal neurons was comparable between genotypes while the dendritic length and complexity of Type II multipolar neurons were significantly reduced in Het mice. White matter neurons and layer VIb neurons receive synaptic inputs and modulate the process of sensory information and sleep/arousal pattern. Aberrances of these neurons in Disc1 mutants implies altered brain functions in these mice.
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Affiliation(s)
- Shin-Hwa Tsai
- School of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chih-Yu Tsao
- Graduate Institute of Anatomy and Cell Biology, National Taiwan University, Taipei, Taiwan
| | - Li-Jen Lee
- School of Medicine, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Anatomy and Cell Biology, National Taiwan University, Taipei, Taiwan
- Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan
- Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan
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22
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Georgiev DD, Kolev SK, Cohen E, Glazebrook JF. Computational capacity of pyramidal neurons in the cerebral cortex. Brain Res 2020; 1748:147069. [DOI: 10.1016/j.brainres.2020.147069] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 07/26/2020] [Accepted: 08/17/2020] [Indexed: 02/07/2023]
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23
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Staiger JF, Petersen CCH. Neuronal Circuits in Barrel Cortex for Whisker Sensory Perception. Physiol Rev 2020; 101:353-415. [PMID: 32816652 DOI: 10.1152/physrev.00019.2019] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The array of whiskers on the snout provides rodents with tactile sensory information relating to the size, shape and texture of objects in their immediate environment. Rodents can use their whiskers to detect stimuli, distinguish textures, locate objects and navigate. Important aspects of whisker sensation are thought to result from neuronal computations in the whisker somatosensory cortex (wS1). Each whisker is individually represented in the somatotopic map of wS1 by an anatomical unit named a 'barrel' (hence also called barrel cortex). This allows precise investigation of sensory processing in the context of a well-defined map. Here, we first review the signaling pathways from the whiskers to wS1, and then discuss current understanding of the various types of excitatory and inhibitory neurons present within wS1. Different classes of cells can be defined according to anatomical, electrophysiological and molecular features. The synaptic connectivity of neurons within local wS1 microcircuits, as well as their long-range interactions and the impact of neuromodulators, are beginning to be understood. Recent technological progress has allowed cell-type-specific connectivity to be related to cell-type-specific activity during whisker-related behaviors. An important goal for future research is to obtain a causal and mechanistic understanding of how selected aspects of tactile sensory information are processed by specific types of neurons in the synaptically connected neuronal networks of wS1 and signaled to downstream brain areas, thus contributing to sensory-guided decision-making.
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Affiliation(s)
- Jochen F Staiger
- University Medical Center Göttingen, Institute for Neuroanatomy, Göttingen, Germany; and Laboratory of Sensory Processing, Faculty of Life Sciences, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Carl C H Petersen
- University Medical Center Göttingen, Institute for Neuroanatomy, Göttingen, Germany; and Laboratory of Sensory Processing, Faculty of Life Sciences, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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24
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Kanari L, Ramaswamy S, Shi Y, Morand S, Meystre J, Perin R, Abdellah M, Wang Y, Hess K, Markram H. Objective Morphological Classification of Neocortical Pyramidal Cells. Cereb Cortex 2020; 29:1719-1735. [PMID: 30715238 PMCID: PMC6418396 DOI: 10.1093/cercor/bhy339] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 11/20/2018] [Indexed: 12/22/2022] Open
Abstract
A consensus on the number of morphologically different types of pyramidal cells (PCs) in the neocortex has not yet been reached, despite over a century of anatomical studies, due to the lack of agreement on the subjective classifications of neuron types, which is based on expert analyses of neuronal morphologies. Even for neurons that are visually distinguishable, there is no common ground to consistently define morphological types. The objective classification of PCs can be achieved with methods from algebraic topology, and the dendritic arborization is sufficient for the reliable identification of distinct types of cortical PCs. Therefore, we objectively identify 17 types of PCs in the rat somatosensory cortex. In addition, we provide a solution to the challenging problem of whether 2 similar neurons belong to different types or to a continuum of the same type. Our topological classification does not require expert input, is stable, and helps settle the long-standing debate on whether cell-types are discrete or continuous morphological variations of each other.
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Affiliation(s)
- Lida Kanari
- Blue Brain Project, Brain and Mind Institute, EPFL, Campus Biotech: CH 1202, Geneva, Switzerland
| | - Srikanth Ramaswamy
- Blue Brain Project, Brain and Mind Institute, EPFL, Campus Biotech: CH 1202, Geneva, Switzerland
| | - Ying Shi
- Blue Brain Project, Brain and Mind Institute, EPFL, Campus Biotech: CH 1202, Geneva, Switzerland
| | - Sebastien Morand
- Laboratory for Topology and Neuroscience, Brain Mind Institute, EPFL, CH 1015, Lausanne, Switzerland
| | - Julie Meystre
- Laboratory of Neural Microcircuitry, Brain Mind Institute, EPFL, CH 1015, Lausanne, Switzerland
| | - Rodrigo Perin
- Laboratory of Neural Microcircuitry, Brain Mind Institute, EPFL, CH 1015, Lausanne, Switzerland
| | - Marwan Abdellah
- Blue Brain Project, Brain and Mind Institute, EPFL, Campus Biotech: CH 1202, Geneva, Switzerland
| | - Yun Wang
- School of Optometry and Ophthalmology, Wenzhou Medical College, Wenzhou, Zhejiang, PR China.,Allen Institute for Brain Science, Seattle, WA, USA
| | - Kathryn Hess
- Laboratory for Topology and Neuroscience, Brain Mind Institute, EPFL, CH 1015, Lausanne, Switzerland
| | - Henry Markram
- Blue Brain Project, Brain and Mind Institute, EPFL, Campus Biotech: CH 1202, Geneva, Switzerland.,Laboratory of Neural Microcircuitry, Brain Mind Institute, EPFL, CH 1015, Lausanne, Switzerland
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25
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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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26
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Yakoubi R, Rollenhagen A, von Lehe M, Miller D, Walkenfort B, Hasenberg M, Sätzler K, Lübke JH. Ultrastructural heterogeneity of layer 4 excitatory synaptic boutons in the adult human temporal lobe neocortex. eLife 2019; 8:48373. [PMID: 31746736 PMCID: PMC6919978 DOI: 10.7554/elife.48373] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 11/19/2019] [Indexed: 01/09/2023] Open
Abstract
Synapses are fundamental building blocks controlling and modulating the ‘behavior’ of brain networks. How their structural composition, most notably their quantitative morphology underlie their computational properties remains rather unclear, particularly in humans. Here, excitatory synaptic boutons (SBs) in layer 4 (L4) of the temporal lobe neocortex (TLN) were quantitatively investigated. Biopsies from epilepsy surgery were used for fine-scale and tomographic electron microscopy (EM) to generate 3D-reconstructions of SBs. Particularly, the size of active zones (AZs) and that of the three functionally defined pools of synaptic vesicles (SVs) were quantified. SBs were comparatively small (~2.50 μm2), with a single AZ (~0.13 µm2); preferentially established on spines. SBs had a total pool of ~1800 SVs with strikingly large readily releasable (~20), recycling (~80) and resting pools (~850). Thus, human L4 SBs may act as ‘amplifiers’ of signals from the sensory periphery, integrate, synchronize and modulate intra- and extracortical synaptic activity.
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Affiliation(s)
- Rachida Yakoubi
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Jülich, Germany
| | - Astrid Rollenhagen
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Jülich, Germany
| | - Marec von Lehe
- Department of Neurosurgery, Knappschaftskrankenhaus Bochum, Bochum, Germany.,Department of Neurosurgery, Brandenburg Medical School, Ruppiner Clinics, Neuruppin, Germany
| | - Dorothea Miller
- Department of Neurosurgery, Knappschaftskrankenhaus Bochum, Bochum, Germany
| | - Bernd Walkenfort
- Medical Research Centre, IMCES Electron Microscopy Unit (EMU), University Hospital Essen, Essen, Germany
| | - Mike Hasenberg
- Medical Research Centre, IMCES Electron Microscopy Unit (EMU), University Hospital Essen, Essen, Germany
| | - Kurt Sätzler
- School of Biomedical Sciences, University of Ulster, Londonderry, United Kingdom
| | - Joachim Hr Lübke
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, Faculty of Medicine, RWTH University Hospital Aachen, Aachen, Germany.,JARA Translational Brain Medicine, Jülich/Aachen, Germany
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27
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Arzt M, Sakmann B, Meyer HS. Anatomical Correlates of Local, Translaminar, and Transcolumnar Inhibition by Layer 6 GABAergic Interneurons in Somatosensory Cortex. Cereb Cortex 2019; 28:2763-2774. [PMID: 28981591 DOI: 10.1093/cercor/bhx156] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Indexed: 01/01/2023] Open
Abstract
In the vibrissal area of rodent somatosensory cortex, information on whisker stimulation is processed by neuronal networks in a corresponding cortical column. To understand how sensory stimuli are represented in a column, it is essential to identify cell types constituting these networks. Layer 6 (L6) comprises 25% of all neurons in a column. In rats, 430 of these are inhibitory interneurons (INs). Little is known about the axon projection of L6 INs with reference to columnar and laminar organization. We quantified axonal projections of L6 INs (n = 68) with reference to columns and layers in somatosensory cortex of rats. We found distinct projection types differentially targeting layers of a cortical column. The majority of L6 INs did not show a column-specific innervation, densely projecting to neighboring columns as well as the home column. However, a small fraction targeted granular and supragranular layers, where axon projections were confined to the home column. We also quantified putative innervation of pyramidal cells as a functional correlate of axonal distribution. Electrophysiological properties were not correlated to axon projection. The quantitative data on axonal projections and electrophysiological properties of L6 INs can guide future studies investigating cortical processing of sensory information at the single cell level.
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Affiliation(s)
- Marlene Arzt
- Digital Neuroanatomy, Max Planck Florida Institute for Neuroscience, Jupiter, FL, USA
| | - Bert Sakmann
- Digital Neuroanatomy, Max Planck Florida Institute for Neuroscience, Jupiter, FL, USA
| | - Hanno S Meyer
- Digital Neuroanatomy, Max Planck Florida Institute for Neuroscience, Jupiter, FL, USA
- Cellular Neurosurgery Research Group, Department of Neurosurgery, Technical University of Munich, Munich, Germany
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28
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Cotel F, Fletcher LN, Kalita-de Croft S, Apergis-Schoute J, Williams SR. Cell Class-Dependent Intracortical Connectivity and Output Dynamics of Layer 6 Projection Neurons of the Rat Primary Visual Cortex. Cereb Cortex 2019; 28:2340-2350. [PMID: 28591797 DOI: 10.1093/cercor/bhx134] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Indexed: 11/14/2022] Open
Abstract
Neocortical information processing is powerfully influenced by the activity of layer 6 projection neurons through control of local intracortical and subcortical circuitry. Morphologically distinct classes of layer 6 projection neuron have been identified in the mammalian visual cortex, which exhibit contrasting receptive field properties, but little information is available on their functional specificity. To address this we combined anatomical tracing techniques with high-resolution patch-clamp recording to identify morphological and functional distinct classes of layer 6 projection neurons in the rat primary visual cortex, which innervated separable subcortical territories. Multisite whole-cell recordings in brain slices revealed that corticoclaustral and corticothalamic layer 6 projection neurons exhibited similar somatically recorded electrophysiological properties. These classes of layer 6 projection neurons were sparsely and reciprocally synaptically interconnected, but could be differentiated by cell-class, but not target-cell-dependent rules of use-dependent depression and facilitation of unitary excitatory synaptic output. Corticoclaustral and corticothalamic layer 6 projection neurons were differentially innervated by columnar excitatory circuitry, with corticoclaustral, but not corticothalamic, neurons powerfully driven by layer 4 pyramidal neurons, and long-range pathways conveyed in neocortical layer 1. Our results therefore reveal projection target-specific, functionally distinct, streams of layer 6 output in the rodent neocortex.
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Affiliation(s)
- Florence Cotel
- Queensland Brain Institute, The University of Queensland, Brisbane QLD, Australia
| | - Lee N Fletcher
- Queensland Brain Institute, The University of Queensland, Brisbane QLD, Australia
| | | | - John Apergis-Schoute
- Department of Neuroscience, Psychology & Behaviour, University of Leicester, University Road, Leicester, UK
| | - Stephen R Williams
- Queensland Brain Institute, The University of Queensland, Brisbane QLD, Australia
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29
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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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30
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Affiliation(s)
- Zoltán Molnár
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
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31
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Kroon T, van Hugte E, van Linge L, Mansvelder HD, Meredith RM. Early postnatal development of pyramidal neurons across layers of the mouse medial prefrontal cortex. Sci Rep 2019; 9:5037. [PMID: 30911152 PMCID: PMC6433913 DOI: 10.1038/s41598-019-41661-9] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 03/12/2019] [Indexed: 12/24/2022] Open
Abstract
Mammalian neocortex is a highly layered structure. Each layer is populated by distinct subtypes of principal cells that are born at different times during development. While the differences between principal cells across layers have been extensively studied, it is not known how the developmental profiles of neurons in different layers compare. Here, we provide a detailed morphological and functional characterisation of pyramidal neurons in mouse mPFC during the first postnatal month, corresponding to known critical periods for synapse and neuron formation in mouse sensory neocortex. Our data demonstrate similar maturation profiles of dendritic morphology and intrinsic properties of pyramidal neurons in both deep and superficial layers. In contrast, the balance of synaptic excitation and inhibition differs in a layer-specific pattern from one to four postnatal weeks of age. Our characterisation of the early development and maturation of pyramidal neurons in mouse mPFC not only demonstrates a comparable time course of postnatal maturation to that in other neocortical circuits, but also implies that consideration of layer- and time-specific changes in pyramidal neurons may be relevant for studies in mouse models of neuropsychiatric and neurodevelopmental disorders.
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Affiliation(s)
- Tim Kroon
- Department of Integrative Neurophysiology, Center for Neurogenomics & Cognitive Research, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.
- MRC Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology & Neuroscience, King's College London, New Hunt's House, Guy's Campus, London, SE1 1UL, UK.
| | - Eline van Hugte
- Department of Integrative Neurophysiology, Center for Neurogenomics & Cognitive Research, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
- Department Cognitive Neurosciences, Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Geert Grooteplein 10 Noord, 6500 HB, Nijmegen, The Netherlands
| | - Lola van Linge
- Department of Integrative Neurophysiology, Center for Neurogenomics & Cognitive Research, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
- Department of Functional Genomics, Center for Neurogenomics & Cognitive Research, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics & Cognitive Research, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Rhiannon M Meredith
- Department of Integrative Neurophysiology, Center for Neurogenomics & Cognitive Research, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
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32
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Wang Y, Ye M, Kuang X, Li Y, Hu S. A simplified morphological classification scheme for pyramidal cells in six layers of primary somatosensory cortex of juvenile rats. IBRO Rep 2018; 5:74-90. [PMID: 30450442 PMCID: PMC6222978 DOI: 10.1016/j.ibror.2018.10.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 10/08/2018] [Accepted: 10/09/2018] [Indexed: 01/01/2023] Open
Abstract
The majority of neurons in the neocortex are excitatory pyramidal cells (PCs). Many systematic classification schemes have been proposed based the neuronal morphology, the chemical composition, and the synaptic connectivity, etc. Recently, a cortical column of primary somatosensory cortex (SSC) has been reconstruction and functionally simulated (Markram et al., 2015). Putting forward from this study, here we proposed a simplified classification scheme for PCs in all layers of the SSC by mainly identifying apical dendritic morphology based on a large data set of 3D neuron reconstructions. We used this scheme to classify three types in layer 2, two in layer 3, three in layer 4, four in layer 5, and six types in layer 6. These PC types were visually distinguished and confirmed by quantitative differences in their morphometric properties. The classes yielded using this scheme largely corresponded with PC classes that were defined previously based on other neuronal and synaptic properties such as long-range projects and synaptic innervations, further validating its applicability. Therefore, the morphology information of apical dendrites is sufficient for a simple scheme to classify a spectrum of anatomical types of PCs in the SSC.
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Affiliation(s)
- Yun Wang
- School of Optometry & Ophthalmology, Wenzhou Medical University, Wenzhou, Zhejiang, P. R. China
- Allen Institute for Brain Science, Seattle, WA, USA
| | - Min Ye
- School of Optometry & Ophthalmology, Wenzhou Medical University, Wenzhou, Zhejiang, P. R. China
| | - Xiuli Kuang
- School of Optometry & Ophthalmology, Wenzhou Medical University, Wenzhou, Zhejiang, P. R. China
| | - Yaoyao Li
- School of Optometry & Ophthalmology, Wenzhou Medical University, Wenzhou, Zhejiang, P. R. China
| | - Shisi Hu
- School of Optometry & Ophthalmology, Wenzhou Medical University, Wenzhou, Zhejiang, P. R. China
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33
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Luhmann HJ, Kirischuk S, Kilb W. The Superior Function of the Subplate in Early Neocortical Development. Front Neuroanat 2018; 12:97. [PMID: 30487739 PMCID: PMC6246655 DOI: 10.3389/fnana.2018.00097] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 10/29/2018] [Indexed: 12/25/2022] Open
Abstract
During early development the structure and function of the cerebral cortex is critically organized by subplate neurons (SPNs), a mostly transient population of glutamatergic and GABAergic neurons located below the cortical plate. At the molecular and morphological level SPNs represent a rather diverse population of cells expressing a variety of genetic markers and revealing different axonal-dendritic morphologies. Electrophysiologically SPNs are characterized by their rather mature intrinsic membrane properties and firing patterns. They are connected via electrical and chemical synapses to local and remote neurons, e.g., thalamic relay neurons forming the first thalamocortical input to the cerebral cortex. Therefore SPNs are robustly activated at pre- and perinatal stages by the sensory periphery. Although SPNs play pivotal roles in early neocortical activity, development and plasticity, they mostly disappear by programmed cell death during further maturation. On the one hand, SPNs may be selectively vulnerable to hypoxia-ischemia contributing to brain damage, on the other hand there is some evidence that enhanced survival rates or alterations in SPN distribution may contribute to the etiology of neurological or psychiatric disorders. This review aims to give a comprehensive and up-to-date overview on the many functions of SPNs during early physiological and pathophysiological development of the cerebral cortex.
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Affiliation(s)
- Heiko J Luhmann
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Sergei Kirischuk
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Werner Kilb
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
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34
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Modelling brain-wide neuronal morphology via rooted Cayley trees. Sci Rep 2018; 8:15666. [PMID: 30353025 PMCID: PMC6199272 DOI: 10.1038/s41598-018-34050-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 10/05/2018] [Indexed: 12/16/2022] Open
Abstract
Neuronal morphology is an essential element for brain activity and function. We take advantage of current availability of brain-wide neuron digital reconstructions of the Pyramidal cells from a mouse brain, and analyze several emergent features of brain-wide neuronal morphology. We observe that axonal trees are self-affine while dendritic trees are self-similar. We also show that tree size appear to be random, independent of the number of dendrites within single neurons. Moreover, we consider inhomogeneous branching model which stochastically generates rooted 3-Cayley trees for the brain-wide neuron topology. Based on estimated order-dependent branching probability from actual axonal and dendritic trees, our inhomogeneous model quantitatively captures a number of topological features including size and shape of both axons and dendrites. This sheds lights on a universal mechanism behind the topological formation of brain-wide axonal and dendritic trees.
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35
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Deitcher Y, Eyal G, Kanari L, Verhoog MB, Atenekeng Kahou GA, Mansvelder HD, de Kock CPJ, Segev I. Comprehensive Morpho-Electrotonic Analysis Shows 2 Distinct Classes of L2 and L3 Pyramidal Neurons in Human Temporal Cortex. Cereb Cortex 2018; 27:5398-5414. [PMID: 28968789 PMCID: PMC5939232 DOI: 10.1093/cercor/bhx226] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Indexed: 12/31/2022] Open
Abstract
There have been few quantitative characterizations of the morphological, biophysical, and cable properties of neurons in the human neocortex. We employed feature-based statistical methods on a rare data set of 60 3D reconstructed pyramidal neurons from L2 and L3 in the human temporal cortex (HL2/L3 PCs) removed after brain surgery. Of these cells, 25 neurons were also characterized physiologically. Thirty-two morphological features were analyzed (e.g., dendritic surface area, 36 333 ± 18 157 μm2; number of basal trees, 5.55 ± 1.47; dendritic diameter, 0.76 ± 0.28 μm). Eighteen features showed a significant gradual increase with depth from the pia (e.g., dendritic length and soma radius). The other features showed weak or no correlation with depth (e.g., dendritic diameter). The basal dendritic terminals in HL2/L3 PCs are particularly elongated, enabling multiple nonlinear processing units in these dendrites. Unlike the morphological features, the active biophysical features (e.g., spike shapes and rates) and passive/cable features (e.g., somatic input resistance, 47.68 ± 15.26 MΩ, membrane time constant, 12.03 ± 1.79 ms, average dendritic cable length, 0.99 ± 0.24) were depth-independent. A novel descriptor for apical dendritic topology yielded 2 distinct classes, termed hereby as “slim-tufted” and “profuse-tufted” HL2/L3 PCs; the latter class tends to fire at higher rates. Thus, our morpho-electrotonic analysis shows 2 distinct classes of HL2/L3 PCs.
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Affiliation(s)
- Yair Deitcher
- Department of Neurobiology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.,Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Guy Eyal
- Department of Neurobiology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Lida Kanari
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Campus Biotech, Chemin de Mines, 9, Geneva 1202, Switzerland
| | - Matthijs B Verhoog
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam NL-1081 HV, The Netherlands
| | - Guy Antoine Atenekeng Kahou
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Campus Biotech, Chemin de Mines, 9, Geneva 1202, Switzerland
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam NL-1081 HV, The Netherlands
| | - Christiaan P J de Kock
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam NL-1081 HV, The Netherlands
| | - Idan Segev
- Department of Neurobiology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.,Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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36
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Hoerder-Suabedissen A, Hayashi S, Upton L, Nolan Z, Casas-Torremocha D, Grant E, Viswanathan S, Kanold PO, Clasca F, Kim Y, Molnár Z. Subset of Cortical Layer 6b Neurons Selectively Innervates Higher Order Thalamic Nuclei in Mice. Cereb Cortex 2018; 28:1882-1897. [PMID: 29481606 PMCID: PMC6018949 DOI: 10.1093/cercor/bhy036] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 01/25/2018] [Accepted: 01/28/2018] [Indexed: 12/16/2022] Open
Abstract
The thalamus receives input from 3 distinct cortical layers, but input from only 2 of these has been well characterized. We therefore investigated whether the third input, derived from layer 6b, is more similar to the projections from layer 6a or layer 5. We studied the projections of a restricted population of deep layer 6 cells ("layer 6b cells") taking advantage of the transgenic mouse Tg(Drd1a-cre)FK164Gsat/Mmucd (Drd1a-Cre), that selectively expresses Cre-recombinase in a subpopulation of layer 6b neurons across the entire cortical mantle. At P8, 18% of layer 6b neurons are labeled with Drd1a-Cre::tdTomato in somatosensory cortex (SS), and some co-express known layer 6b markers. Using Cre-dependent viral tracing, we identified topographical projections to higher order thalamic nuclei. VGluT1+ synapses formed by labeled layer 6b projections were found in posterior thalamic nucleus (Po) but not in the (pre)thalamic reticular nucleus (TRN). The lack of TRN collaterals was confirmed with single-cell tracing from SS. Transmission electron microscopy comparison of terminal varicosities from layer 5 and layer 6b axons in Po showed that L6b varicosities are markedly smaller and simpler than the majority from L5. Our results suggest that L6b projections to the thalamus are distinct from both L5 and L6a projections.
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Affiliation(s)
| | - Shuichi Hayashi
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Louise Upton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Zachary Nolan
- Neural and Behavioral Sciences, Pennsylvania State University, 500 University Drive, Hershey, PA 17033, USA
| | - Diana Casas-Torremocha
- Department of Anatomy, Histology and Neuroscience, School of Medicine, Autónoma University, Madrid, Spain
| | - Eleanor Grant
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Sarada Viswanathan
- Department of Biology, University of Maryland, 1116 Biosciences Building,College Park, MD 20742, USA
| | - Patrick O Kanold
- Department of Biology, University of Maryland, 1116 Biosciences Building,College Park, MD 20742, USA
| | - Francisco Clasca
- Department of Anatomy, Histology and Neuroscience, School of Medicine, Autónoma University, Madrid, Spain
| | - Yongsoo Kim
- Neural and Behavioral Sciences, Pennsylvania State University, 500 University Drive, Hershey, PA 17033, USA
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
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37
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Marx M, Qi G, Hanganu-Opatz IL, Kilb W, Luhmann HJ, Feldmeyer D. Neocortical Layer 6B as a Remnant of the Subplate - A Morphological Comparison. Cereb Cortex 2018; 27:1011-1026. [PMID: 26637449 DOI: 10.1093/cercor/bhv279] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The fate of the subplate (SP) is still a matter of debate. The SP and layer 6 (which is ontogenetically the oldest and innermost neocortical lamina) develop coincidentally. Yet, the function of sublamina 6B is largely unknown. It has been suggested that it consists partly of neurons from the transient SP, however, experimental evidence for this hypothesis is still missing. To obtain first insights into the neuronal complement of layer 6B in the somatosensory rat barrel cortex, we used biocytin stainings of SP neurons (aged 0-4 postnatal days, PND) and layer 6B neurons (PND 11-35) obtained during in vitro whole-cell patch-clamp recordings. Neurons were reconstructed for a quantitative characterization of their axonal and dendritic morphology. An unsupervised cluster analysis revealed that the SP and layer 6B consist of heterogeneous but comparable neuronal cell populations. Both contain 5 distinct spine-bearing cell types whose relative fractions change with increasing age. Pyramidal cells were more prominent in layer 6B, whereas non-pyramidal neurons were less frequent. Because of the high morphological similarity of SP and layer 6B neurons, we suggest that layer 6B consists of persistent non-pyramidal neurons from the SP and cortical L6B pyramidal neurons.
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Affiliation(s)
- Manuel Marx
- Institute of Neuroscience and Medicine, INM-2, Research Centre Jülich, D-52428 Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, D-52074 Aachen, Germany
| | - Guanxiao Qi
- Institute of Neuroscience and Medicine, INM-2, Research Centre Jülich, D-52428 Jülich, Germany
| | - Ileana L Hanganu-Opatz
- Developmental Neurophysiology, Institute of Neuroanatomy, Centre for Molecular Neurobiology Hamburg (ZMNH), D-20251 Hamburg, Germany
| | - Werner Kilb
- Institute of Physiology, University Medical Centre of the Johannes Gutenberg-University Mainz, D-55128 Mainz, Germany
| | - Heiko J Luhmann
- Institute of Physiology, University Medical Centre of the Johannes Gutenberg-University Mainz, D-55128 Mainz, Germany
| | - Dirk Feldmeyer
- Institute of Neuroscience and Medicine, INM-2, Research Centre Jülich, D-52428 Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, D-52074 Aachen, Germany.,Jülich Aachen Research Alliance, Translational Brain Medicine (JARA Brain), D-52074 Aachen, Germany
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38
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Radnikow G, Feldmeyer D. Layer- and Cell Type-Specific Modulation of Excitatory Neuronal Activity in the Neocortex. Front Neuroanat 2018; 12:1. [PMID: 29440997 PMCID: PMC5797542 DOI: 10.3389/fnana.2018.00001] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 01/04/2018] [Indexed: 01/08/2023] Open
Abstract
From an anatomical point of view the neocortex is subdivided into up to six layers depending on the cortical area. This subdivision has been described already by Meynert and Brodmann in the late 19/early 20. century and is mainly based on cytoarchitectonic features such as the size and location of the pyramidal cell bodies. Hence, cortical lamination is originally an anatomical concept based on the distribution of excitatory neuron. However, it has become apparent in recent years that apart from the layer-specific differences in morphological features, many functional properties of neurons are also dependent on cortical layer or cell type. Such functional differences include changes in neuronal excitability and synaptic activity by neuromodulatory transmitters. Many of these neuromodulators are released from axonal afferents from subcortical brain regions while others are released intrinsically. In this review we aim to describe layer- and cell-type specific differences in the effects of neuromodulator receptors in excitatory neurons in layers 2–6 of different cortical areas. We will focus on the neuromodulator systems using adenosine, acetylcholine, dopamine, and orexin/hypocretin as examples because these neuromodulator systems show important differences in receptor type and distribution, mode of release and functional mechanisms and effects. We try to summarize how layer- and cell type-specific neuromodulation may affect synaptic signaling in cortical microcircuits.
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Affiliation(s)
- Gabriele Radnikow
- Research Centre Jülich, Institute of Neuroscience and Medicine, INM-10, Jülich, Germany
| | - Dirk Feldmeyer
- Research Centre Jülich, Institute of Neuroscience and Medicine, INM-10, Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Aachen, Germany.,Jülich-Aachen Research Alliance - Translational Brain Medicine, Jülich, Germany
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39
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Case L, Lyons DJ, Broberger C. Desynchronization of the Rat Cortical Network and Excitation of White Matter Neurons by Neurotensin. Cereb Cortex 2017; 27:2671-2685. [PMID: 27095826 DOI: 10.1093/cercor/bhw100] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Cortical network activity correlates with vigilance state: Deep sleep is characterized by slow, synchronized oscillations, whereas desynchronized, stochastic discharge is typical of the waking state. Neuropeptides, such as orexin and substance P but also neurotensin (NT), promote arousal. Relatively little is known about if NT can directly affect the cortical network, and if so, through which mechanisms and cellular targets. Here, we addressed these issues using rat in vitro cortex preparations. Following NT application specifically to deeper layers, slow oscillation activity was attenuated with a significant reduction in UP state frequency. The cortical response to thalamic stimulation exhibited enhanced temporal precision in the presence of NT, consistent with the transition in vivo from sleep to wakefulness. These changes were associated with a relative shift toward inhibition in the excitation/inhibition balance. Whole-cell recordings from layer 6 revealed presynaptically driven NT-induced inhibition of pyramidal neurons and excitation of fast-spiking interneurons. Deeper in the cortex, neurons within the white matter (WM) were strongly depolarized by NT application. The colocalization of NT and tyrosine hydroxylase immunoreactivities in deep layer fibers throughout the cortical mantle indicates mediation via dopaminergic systems. These data suggest a cortical mechanism for NT-induced wakefulness and support a role for WM neurons in state control.
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Affiliation(s)
- Lovisa Case
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - David J Lyons
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Current address: Rowett Institute of Nutrition and Health, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, UK
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40
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Wenger Combremont AL, Bayer L, Dupré A, Mühlethaler M, Serafin M. Slow Bursting Neurons of Mouse Cortical Layer 6b Are Depolarized by Hypocretin/Orexin and Major Transmitters of Arousal. Front Neurol 2016; 7:88. [PMID: 27379007 PMCID: PMC4908144 DOI: 10.3389/fneur.2016.00088] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/30/2016] [Indexed: 11/17/2022] Open
Abstract
Neurons firing spontaneously in bursts in the absence of synaptic transmission have been previously recorded in different layers of cortical brain slices. It has been suggested that such neurons could contribute to the generation of alternating UP and DOWN states, a pattern of activity seen during slow-wave sleep. Here, we show that in layer 6b (L6b), known from our previous studies to contain neurons highly responsive to the wake-promoting transmitter hypocretin/orexin (hcrt/orx), there is a set of neurons, endowed with distinct intrinsic properties, which displayed a strong propensity to fire spontaneously in rhythmic bursts. In response to small depolarizing steps, they responded with a delayed firing of action potentials which, upon higher depolarizing steps, invariably inactivated and were followed by a depolarized plateau potential and a depolarizing afterpotential. These cells also displayed a strong hyperpolarization-activated rectification compatible with the presence of an Ih current. Most L6b neurons with such properties were able to fire spontaneously in bursts. Their bursting activity was of intrinsic origin as it persisted not only in presence of blockers of ionotropic glutamatergic and GABAergic receptors but also in a condition of complete synaptic blockade. However, a small number of these neurons displayed a mix of intrinsic bursting and synaptically driven recurrent UP and DOWN states. Most of the bursting L6b neurons were depolarized and excited by hcrt/orx through a direct postsynaptic mechanism that led to tonic firing and eventually inactivation. Similarly, they were directly excited by noradrenaline, histamine, dopamine, and neurotensin. Finally, the intracellular injection of these cells with dye and their subsequent Neurolucida reconstruction indicated that they were spiny non-pyramidal neurons. These results lead us to suggest that the propensity for slow rhythmic bursting of this set of L6b neurons could be directly impeded by hcrt/orx and other wake-promoting transmitters.
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Affiliation(s)
| | - Laurence Bayer
- Département des neurosciences fondamentales, Centre Médical Universitaire, Geneva, Switzerland; Centre de médecine du sommeil, Hôpitaux Universitaires de Genève, Geneva, Switzerland
| | - Anouk Dupré
- Département des neurosciences fondamentales, Centre Médical Universitaire , Geneva , Switzerland
| | - Michel Mühlethaler
- Département des neurosciences fondamentales, Centre Médical Universitaire , Geneva , Switzerland
| | - Mauro Serafin
- Département des neurosciences fondamentales, Centre Médical Universitaire , Geneva , Switzerland
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41
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Mohan H, Verhoog MB, Doreswamy KK, Eyal G, Aardse R, Lodder BN, Goriounova NA, Asamoah B, B Brakspear ABC, Groot C, van der Sluis S, Testa-Silva G, Obermayer J, Boudewijns ZSRM, Narayanan RT, Baayen JC, Segev I, Mansvelder HD, de Kock CPJ. Dendritic and Axonal Architecture of Individual Pyramidal Neurons across Layers of Adult Human Neocortex. Cereb Cortex 2015; 25:4839-53. [PMID: 26318661 PMCID: PMC4635923 DOI: 10.1093/cercor/bhv188] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The size and shape of dendrites and axons are strong determinants of neuronal information processing. Our knowledge on neuronal structure and function is primarily based on brains of laboratory animals. Whether it translates to human is not known since quantitative data on "full" human neuronal morphologies are lacking. Here, we obtained human brain tissue during resection surgery and reconstructed basal and apical dendrites and axons of individual neurons across all cortical layers in temporal cortex (Brodmann area 21). Importantly, morphologies did not correlate to etiology, disease severity, or disease duration. Next, we show that human L(ayer) 2 and L3 pyramidal neurons have 3-fold larger dendritic length and increased branch complexity with longer segments compared with temporal cortex neurons from macaque and mouse. Unsupervised cluster analysis classified 88% of human L2 and L3 neurons into human-specific clusters distinct from mouse and macaque neurons. Computational modeling of passive electrical properties to assess the functional impact of large dendrites indicates stronger signal attenuation of electrical inputs compared with mouse. We thus provide a quantitative analysis of "full" human neuron morphologies and present direct evidence that human neurons are not "scaled-up" versions of rodent or macaque neurons, but have unique structural and functional properties.
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Affiliation(s)
- Hemanth Mohan
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Matthijs B Verhoog
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Keerthi K Doreswamy
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Guy Eyal
- Department of Neurobiology and Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Romy Aardse
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Brendan N Lodder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Natalia A Goriounova
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Boateng Asamoah
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - A B Clementine B Brakspear
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Colin Groot
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Sophie van der Sluis
- Department of Clinical Genetics, Section Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, VU Medical Center, Amsterdam, The Netherlands
| | - Guilherme Testa-Silva
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Joshua Obermayer
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Zimbo S R M Boudewijns
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Rajeevan T Narayanan
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Johannes C Baayen
- Department of Neurosurgery, VU University Medical Center, Amsterdam 1081 HV, The Netherlands
| | - Idan Segev
- Department of Neurobiology and Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Christiaan P J de Kock
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, Amsterdam 1081 HV, The Netherlands
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42
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Ramaswamy S, Markram H. Anatomy and physiology of the thick-tufted layer 5 pyramidal neuron. Front Cell Neurosci 2015; 9:233. [PMID: 26167146 PMCID: PMC4481152 DOI: 10.3389/fncel.2015.00233] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 06/08/2015] [Indexed: 11/13/2022] Open
Abstract
The thick-tufted layer 5 (TTL5) pyramidal neuron is one of the most extensively studied neuron types in the mammalian neocortex and has become a benchmark for understanding information processing in excitatory neurons. By virtue of having the widest local axonal and dendritic arborization, the TTL5 neuron encompasses various local neocortical neurons and thereby defines the dimensions of neocortical microcircuitry. The TTL5 neuron integrates input across all neocortical layers and is the principal output pathway funneling information flow to subcortical structures. Several studies over the past decades have investigated the anatomy, physiology, synaptology, and pathophysiology of the TTL5 neuron. This review summarizes key discoveries and identifies potential avenues of research to facilitate an integrated and unifying understanding on the role of a central neuron in the neocortex.
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Affiliation(s)
- Srikanth Ramaswamy
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Campus Biotech Geneva, Switzerland
| | - Henry Markram
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Campus Biotech Geneva, Switzerland
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43
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Hoerder-Suabedissen A, Molnár Z. Development, evolution and pathology of neocortical subplate neurons. Nat Rev Neurosci 2015; 16:133-46. [DOI: 10.1038/nrn3915] [Citation(s) in RCA: 175] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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44
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Parekh R, Armañanzas R, Ascoli GA. The importance of metadata to assess information content in digital reconstructions of neuronal morphology. Cell Tissue Res 2015; 360:121-7. [PMID: 25653123 DOI: 10.1007/s00441-014-2103-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 12/21/2014] [Indexed: 12/23/2022]
Abstract
Digital reconstructions of axonal and dendritic arbors provide a powerful representation of neuronal morphology in formats amenable to quantitative analysis, computational modeling, and data mining. Reconstructed files, however, require adequate metadata to identify the appropriate animal species, developmental stage, brain region, and neuron type. Moreover, experimental details about tissue processing, neurite visualization and microscopic imaging are essential to assess the information content of digital morphologies. Typical morphological reconstructions only partially capture the underlying biological reality. Tracings are often limited to certain domains (e.g., dendrites and not axons), may be incomplete due to tissue sectioning, imperfect staining, and limited imaging resolution, or can disregard aspects irrelevant to their specific scientific focus (such as branch thickness or depth). Gauging these factors is critical in subsequent data reuse and comparison. NeuroMorpho.Org is a central repository of reconstructions from many laboratories and experimental conditions. Here, we introduce substantial additions to the existing metadata annotation aimed to describe the completeness of the reconstructed neurons in NeuroMorpho.Org. These expanded metadata form a suitable basis for effective description of neuromorphological data.
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Affiliation(s)
- Ruchi Parekh
- Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA, 22030, USA
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45
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Schnepel P, Kumar A, Zohar M, Aertsen A, Boucsein C. Physiology and Impact of Horizontal Connections in Rat Neocortex. Cereb Cortex 2014; 25:3818-35. [PMID: 25410428 DOI: 10.1093/cercor/bhu265] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Cortical information processing at the cellular level has predominantly been studied in local networks, which are dominated by strong vertical connectivity between layers. However, recent studies suggest that the bulk of axons targeting pyramidal neurons most likely originate from outside this local range, emphasizing the importance of horizontal connections. We mapped a subset of these connections to L5B pyramidal neurons in rat somatosensory cortex with photostimulation, identifying intact projections up to a lateral distance of 2 mm. Our estimates of the spatial distribution of cells presynaptic to L5B pyramids support the idea that the majority is located outside the local volume. The synaptic physiology of horizontal connections does not differ markedly from that of local connections, whereas the layer and cell-type-dependent pattern of innervation does. Apart from L2/3, L6A provides a strong source of horizontal connections. Implementing our data into a spiking neuronal network model shows that more horizontal connections promote robust asynchronous ongoing activity states and reduce noise correlations in stimulus-induced activity.
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Affiliation(s)
- Philipp Schnepel
- Bernstein Center Freiburg, Freiburg 79104, Germany Neurobiology and Biophysics, Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
| | - Arvind Kumar
- Bernstein Center Freiburg, Freiburg 79104, Germany Neurobiology and Biophysics, Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
| | - Mihael Zohar
- Bernstein Center Freiburg, Freiburg 79104, Germany Neurobiology and Biophysics, Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
| | - Ad Aertsen
- Bernstein Center Freiburg, Freiburg 79104, Germany Neurobiology and Biophysics, Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
| | - Clemens Boucsein
- Bernstein Center Freiburg, Freiburg 79104, Germany Neurobiology and Biophysics, Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
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46
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Vélez-Fort M, Rousseau CV, Niedworok CJ, Wickersham IR, Rancz EA, Brown APY, Strom M, Margrie TW. The stimulus selectivity and connectivity of layer six principal cells reveals cortical microcircuits underlying visual processing. Neuron 2014; 83:1431-43. [PMID: 25175879 PMCID: PMC4175007 DOI: 10.1016/j.neuron.2014.08.001] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2014] [Indexed: 01/05/2023]
Abstract
Sensory computations performed in the neocortex involve layer six (L6) cortico-cortical (CC) and cortico-thalamic (CT) signaling pathways. Developing an understanding of the physiological role of these circuits requires dissection of the functional specificity and connectivity of the underlying individual projection neurons. By combining whole-cell recording from identified L6 principal cells in the mouse primary visual cortex (V1) with modified rabies virus-based input mapping, we have determined the sensory response properties and upstream monosynaptic connectivity of cells mediating the CC or CT pathway. We show that CC-projecting cells encompass a broad spectrum of selectivity to stimulus orientation and are predominantly innervated by deep layer V1 neurons. In contrast, CT-projecting cells are ultrasparse firing, exquisitely tuned to orientation and direction information, and receive long-range input from higher cortical areas. This segregation in function and connectivity indicates that L6 microcircuits route specific contextual and stimulus-related information within and outside the cortical network. L6 cortico-cortical neurons are broadly tuned to stimulus orientation L6 cortico-thalamic neurons are sparse firing and highly tuned to stimulus orientation L6 cortico-cortical neurons receive input from cells located mostly within V1 L6 cortico-thalamic neurons receive input from higher order cortical areas
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Affiliation(s)
- Mateo Vélez-Fort
- The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Charly V Rousseau
- The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Christian J Niedworok
- The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Ian R Wickersham
- Genetic Neuroengineering Group, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ede A Rancz
- The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Alexander P Y Brown
- The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Molly Strom
- The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Troy W Margrie
- The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK; Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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47
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Hay YA, Andjelic S, Badr S, Lambolez B. Orexin-dependent activation of layer VIb enhances cortical network activity and integration of non-specific thalamocortical inputs. Brain Struct Funct 2014; 220:3497-512. [PMID: 25108310 DOI: 10.1007/s00429-014-0869-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 07/31/2014] [Indexed: 10/24/2022]
Abstract
Neocortical layer VI is critically involved in thalamocortical activity changes during the sleep/wake cycle. It receives dense projections from thalamic nuclei sensitive to the wake-promoting neuropeptides orexins, and its deepest part, layer VIb, is the only cortical lamina reactive to orexins. This convergence of wake-promoting inputs prompted us to investigate how layer VIb can modulate cortical arousal, using patch-clamp recordings and optogenetics in rat brain slices. We found that the majority of layer VIb neurons were excited by nicotinic agonists and orexin through the activation of nicotinic receptors containing α4-α5-β2 subunits and OX2 receptor, respectively. Specific effects of orexin on layer VIb neurons were potentiated by low nicotine concentrations and we used this paradigm to explore their intracortical projections. Co-application of nicotine and orexin increased the frequency of excitatory post-synaptic currents in the ipsilateral cortex, with maximal effect in infragranular layers and minimal effect in layer IV, as well as in the contralateral cortex. The ability of layer VIb to relay thalamocortical inputs was tested using photostimulation of channelrhodopsin-expressing fibers from the orexin-sensitive rhomboid nucleus in the parietal cortex. Photostimulation induced robust excitatory currents in layer VIa neurons that were not pre-synaptically modulated by orexin, but exhibited a delayed, orexin-dependent, component. Activation of layer VIb by orexin enhanced the reliability and spike-timing precision of layer VIa responses to rhomboid inputs. These results indicate that layer VIb acts as an orexin-gated excitatory feedforward loop that potentiates thalamocortical arousal.
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Affiliation(s)
- Y Audrey Hay
- UM CR 18, Neuroscience Paris Seine, Sorbonne Universités, UPMC Univ Paris 06, 75005, Paris, France.
- UMR 8246, Centre National de la Recherche Scientifique (CNRS), Paris, France.
- UMR-S 1130, Institut national de la Santé et de la Recherche Médicale (INSERM), Paris, France.
| | - Sofija Andjelic
- UM CR 18, Neuroscience Paris Seine, Sorbonne Universités, UPMC Univ Paris 06, 75005, Paris, France
- UMR 8246, Centre National de la Recherche Scientifique (CNRS), Paris, France
- UMR-S 1130, Institut national de la Santé et de la Recherche Médicale (INSERM), Paris, France
| | - Sammy Badr
- UM CR 18, Neuroscience Paris Seine, Sorbonne Universités, UPMC Univ Paris 06, 75005, Paris, France
- UMR 8246, Centre National de la Recherche Scientifique (CNRS), Paris, France
- UMR-S 1130, Institut national de la Santé et de la Recherche Médicale (INSERM), Paris, France
| | - Bertrand Lambolez
- UM CR 18, Neuroscience Paris Seine, Sorbonne Universités, UPMC Univ Paris 06, 75005, Paris, France.
- UMR 8246, Centre National de la Recherche Scientifique (CNRS), Paris, France.
- UMR-S 1130, Institut national de la Santé et de la Recherche Médicale (INSERM), Paris, France.
- UMR 8246, Neuroscience Paris Seine, Université Pierre et Marie Curie, 9 quai St Bernard case 16, 75005, Paris, France.
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48
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Kerekes BP, Tóth K, Kaszás A, Chiovini B, Szadai Z, Szalay G, Pálfi D, Bagó A, Spitzer K, Rózsa B, Ulbert I, Wittner L. Combined two-photon imaging, electrophysiological, and anatomical investigation of the human neocortex in vitro. NEUROPHOTONICS 2014; 1:011013. [PMID: 26157969 PMCID: PMC4478968 DOI: 10.1117/1.nph.1.1.011013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 08/19/2014] [Accepted: 08/20/2014] [Indexed: 05/06/2023]
Abstract
Spontaneous synchronous population activity (SPA) can be detected by electrophysiological methods in cortical slices of epileptic patients, maintained in a physiological medium in vitro. In order to gain additional spatial information about the network mechanisms involved in the SPA generation, we combined electrophysiological studies with two-photon imaging. Neocortical slices prepared from postoperative tissue of epileptic and tumor patients were maintained in a dual perfusion chamber in a physiological incubation medium. SPA was recorded with a 24-channel extracellular linear microelectrode covering all neocortical layers. After identifying the electrophysiologically active regions of the slice, bolus loading of neuronal and glial markers was applied on the tissue. SPA-related [Formula: see text] transients were detected in a large population of neighboring neurons with two-photon microscopy, simultaneous with extracellular SPA and intracellular whole-cell patch-clamp recordings. The intracellularly recorded cells were filled for subsequent anatomy. The cells were reconstructed in three dimensions and examined with light- and transmission electron microscopy. Combining high spatial resolution two-photon [Formula: see text] imaging techniques and high temporal resolution extra- and intracellular electrophysiology with cellular anatomy may permit a deeper understanding of the structural and functional properties of the human neocortex.
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Affiliation(s)
- Bálint Péter Kerekes
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Institute of Cognitive Neuroscience and Psychology, Budapest, Hungary
| | - Kinga Tóth
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Institute of Cognitive Neuroscience and Psychology, Budapest, Hungary
| | - Attila Kaszás
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Balázs Chiovini
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Zoltán Szadai
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Gergely Szalay
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Dénes Pálfi
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Attila Bagó
- National Institute of Clinical Neuroscience, Department of Neurooncology, Budapest, Hungary
| | - Klaudia Spitzer
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - Balázs Rózsa
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Two-Photon Imaging Center, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary
| | - István Ulbert
- Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, H-1083 Budapest, Práter utca 50/a, Hungary
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Institute of Cognitive Neuroscience and Psychology, Budapest, Hungary
- Address all correspondence to: István Ulbert, E-mail:
| | - Lucia Wittner
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Institute of Cognitive Neuroscience and Psychology, Budapest, Hungary
- National Institute of Clinical Neuroscience, Department of Neurooncology, Budapest, Hungary
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Parekh R, Ascoli GA. Quantitative investigations of axonal and dendritic arbors: development, structure, function, and pathology. Neuroscientist 2014; 21:241-54. [PMID: 24972604 DOI: 10.1177/1073858414540216] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The branching structures of neurons are a long-standing focus of neuroscience. Axonal and dendritic morphology affect synaptic signaling, integration, and connectivity, and their diversity reflects the computational specialization of neural circuits. Altered neuronal morphology accompanies functional changes during development, experience, aging, and disease. Technological improvements continuously accelerate high-throughput tissue processing, image acquisition, and morphological reconstruction. Digital reconstructions of neuronal morphologies allow for complex quantitative analyses that are unattainable from raw images or two-dimensional tracings. Furthermore, digitized morphologies enable computational modeling of biophysically realistic neuronal dynamics. Additionally, reconstructions generated to address specific scientific questions have the potential for continued investigations beyond the original reason for their acquisition. Facilitating multiple reuse are repositories like NeuroMorpho.Org, which ease the sharing of reconstructions. Here, we review selected scientific literature reporting the reconstruction of axonal or dendritic morphology with diverse goals including establishment of neuronal identity, examination of physiological properties, and quantification of developmental or pathological changes. These reconstructions, deposited in NeuroMorpho.Org, have since been used by other investigators in additional research, of which we highlight representative examples. This cycle of data generation, analysis, sharing, and reuse reveals the vast potential of digital reconstructions in quantitative investigations of neuronal morphology.
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Affiliation(s)
- Ruchi Parekh
- Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA, USA
| | - Giorgio A Ascoli
- Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA, USA
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50
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Results on a binding neuron model and their implications for modified hourglass model for neuronal network. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2014; 2013:374878. [PMID: 24396394 PMCID: PMC3876776 DOI: 10.1155/2013/374878] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/27/2013] [Accepted: 11/17/2013] [Indexed: 11/18/2022]
Abstract
The classical models of single neuron like Hodgkin-Huxley point neuron or leaky integrate and fire neuron assume the influence of postsynaptic potentials to last till the neuron fires. Vidybida (2008) in a refreshing departure has proposed models for binding neurons in which the trace of an input is remembered only for a finite fixed period of time after which it is forgotten. The binding neurons conform to the behaviour of real neurons and are applicable in constructing fast recurrent networks for computer modeling. This paper develops explicitly several useful results for a binding neuron like the firing time distribution and other statistical characteristics. We also discuss the applicability of the developed results in constructing a modified hourglass network model in which there are interconnected neurons with excitatory as well as inhibitory inputs. Limited simulation results of the hourglass network are presented.
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