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Reyes I, Faustin A, Tian C, Masurkar AV. Frontal-Variant Alzheimer's Disease: Subregional Distribution of Entorhinal-CA1 Pathology and Pathophysiological Implications. J Neuropsychiatry Clin Neurosci 2024:appineuropsych20230113. [PMID: 38835223 DOI: 10.1176/appi.neuropsych.20230113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Affiliation(s)
- Isabel Reyes
- Center for Cognitive Neurology, Department of Neurology (Reyes, Tian, Masurkar), Alzheimer's Disease Research Center (Faustin, Masurkar), Department of Pathology (Faustin), and Neuroscience Institute (Masurkar), New York University Grossman School of Medicine, New York
| | - Arline Faustin
- Center for Cognitive Neurology, Department of Neurology (Reyes, Tian, Masurkar), Alzheimer's Disease Research Center (Faustin, Masurkar), Department of Pathology (Faustin), and Neuroscience Institute (Masurkar), New York University Grossman School of Medicine, New York
| | - Chengju Tian
- Center for Cognitive Neurology, Department of Neurology (Reyes, Tian, Masurkar), Alzheimer's Disease Research Center (Faustin, Masurkar), Department of Pathology (Faustin), and Neuroscience Institute (Masurkar), New York University Grossman School of Medicine, New York
| | - Arjun V Masurkar
- Center for Cognitive Neurology, Department of Neurology (Reyes, Tian, Masurkar), Alzheimer's Disease Research Center (Faustin, Masurkar), Department of Pathology (Faustin), and Neuroscience Institute (Masurkar), New York University Grossman School of Medicine, New York
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Hanson MA, Bibi N, Safa A, Nagarajan D, Marshall AH, Johantges AC, Wester JC. Development of differential sublaminar feedforward inhibitory circuits in CA1 hippocampus requires Satb2. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.23.576902. [PMID: 38328190 PMCID: PMC10849736 DOI: 10.1101/2024.01.23.576902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Pyramidal cells (PCs) in CA1 hippocampus can be classified by their radial position as deep or superficial and organize into subtype-specific circuits necessary for differential information processing. Specifically, superficial PCs receive fewer inhibitory synapses from parvalbumin (PV)-expressing interneurons than deep PCs, resulting in weaker feedforward inhibition of input from CA3 Schaffer collaterals. Using mice, we investigated mechanisms underlying PC differentiation and the development of this inhibitory circuit motif. We found that expression of the transcriptional regulator SATB2 is biased towards superficial PCs during early postnatal development and necessary to suppress PV+ interneuron synapse formation. In the absence of SATB2, the number of PV+ interneuron synaptic puncta surrounding superficial PCs increases during development to match deep PCs. This results in equivalent inhibitory current strength observed in paired whole-cell recordings, and equivalent feedforward inhibition of Schaffer collateral input. Thus, SATB2 is necessary for superficial PC differentiation and biased feedforward inhibition in CA1.
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Tian C, Reyes I, Masurkar AV. Impact of dendritic spine loss on excitability of hippocampal CA1 pyramidal neurons: a computational study of early Alzheimer disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.20.576500. [PMID: 38328155 PMCID: PMC10849489 DOI: 10.1101/2024.01.20.576500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Synaptic spine loss is an early pathophysiologic hallmark of Alzheimer disease (AD) that precedes overt loss of dendritic architecture and frank neurodegeneration. While spine loss signifies a decreased engagement of postsynaptic neurons by presynaptic targets, the degree to which loss of spines and their passive components impacts the excitability of postsynaptic neurons and responses to surviving synaptic inputs is unclear. Using passive multicompartmental models of CA1 pyramidal neurons (PNs), implicated in early AD, we find that spine loss alone drives a boosting of remaining inputs to their proximal and distal dendrites, targeted by CA3 and entorhinal cortex (EC), respectively. This boosting effect is higher in distal versus proximal dendrites and can be mediated by spine loss restricted to the distal compartment, enough to impact synaptic input integration and somatodendritic backpropagation. This has particular relevance to very early stages of AD in which pathophysiology extends from EC to CA1.
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Varghese N, Moscoso B, Chavez A, Springer K, Ortiz E, Soh H, Santaniello S, Maheshwari A, Tzingounis AV. KCNQ2/3 Gain-of-Function Variants and Cell Excitability: Differential Effects in CA1 versus L2/3 Pyramidal Neurons. J Neurosci 2023; 43:6479-6494. [PMID: 37607817 PMCID: PMC10513074 DOI: 10.1523/jneurosci.0980-23.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 08/09/2023] [Accepted: 08/15/2023] [Indexed: 08/24/2023] Open
Abstract
Gain-of-function (GOF) pathogenic variants in the potassium channels KCNQ2 and KCNQ3 lead to hyperexcitability disorders such as epilepsy and autism spectrum disorders. However, the underlying cellular mechanisms of how these variants impair forebrain function are unclear. Here, we show that the R201C variant in KCNQ2 has opposite effects on the excitability of two types of mouse pyramidal neurons of either sex, causing hyperexcitability in layer 2/3 (L2/3) pyramidal neurons and hypoexcitability in CA1 pyramidal neurons. Similarly, the homologous R231C variant in KCNQ3 leads to hyperexcitability in L2/3 pyramidal neurons and hypoexcitability in CA1 pyramidal neurons. However, the effects of KCNQ3 gain-of-function on excitability are specific to superficial CA1 pyramidal neurons. These findings reveal a new level of complexity in the function of KCNQ2 and KCNQ3 channels in the forebrain and provide a framework for understanding the effects of gain-of-function variants and potassium channels in the brain.SIGNIFICANCE STATEMENT KCNQ2/3 gain-of-function (GOF) variants lead to severe forms of neurodevelopmental disorders, but the mechanisms by which these channels affect neuronal activity are poorly understood. In this study, using a series of transgenic mice we demonstrate that the same KCNQ2/3 GOF variants can lead to either hyperexcitability or hypoexcitability in different types of pyramidal neurons [CA1 vs layer (L)2/3]. Additionally, we show that expression of the recurrent KCNQ2 GOF variant R201C in forebrain pyramidal neurons could lead to seizures and SUDEP. Our data suggest that the effects of KCNQ2/3 GOF variants depend on specific cell types and brain regions, possibly accounting for the diverse range of phenotypes observed in individuals with KCNQ2/3 GOF variants.
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Affiliation(s)
- Nissi Varghese
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269
| | - Bruno Moscoso
- Department of Neurology, Baylor College of Medicine, Houston, Texas 77030
| | - Ana Chavez
- Department of Neurology, Baylor College of Medicine, Houston, Texas 77030
| | - Kristen Springer
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269
| | - Erika Ortiz
- Department of Neurology, Baylor College of Medicine, Houston, Texas 77030
| | - Heun Soh
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269
| | - Sabato Santaniello
- Department of Biomedical Engineering and Connecticut Institute for the Brain and Cognitive Sciences, University of Connecticut, Storrs, Connecticut 06269
| | - Atul Maheshwari
- Department of Neurology, Baylor College of Medicine, Houston, Texas 77030
| | - Anastasios V Tzingounis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269
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Etter G, Carmichael JE, Williams S. Linking temporal coordination of hippocampal activity to memory function. Front Cell Neurosci 2023; 17:1233849. [PMID: 37720546 PMCID: PMC10501408 DOI: 10.3389/fncel.2023.1233849] [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: 06/02/2023] [Accepted: 08/01/2023] [Indexed: 09/19/2023] Open
Abstract
Oscillations in neural activity are widespread throughout the brain and can be observed at the population level through the local field potential. These rhythmic patterns are associated with cycles of excitability and are thought to coordinate networks of neurons, in turn facilitating effective communication both within local circuits and across brain regions. In the hippocampus, theta rhythms (4-12 Hz) could contribute to several key physiological mechanisms including long-range synchrony, plasticity, and at the behavioral scale, support memory encoding and retrieval. While neurons in the hippocampus appear to be temporally coordinated by theta oscillations, they also tend to fire in sequences that are developmentally preconfigured. Although loss of theta rhythmicity impairs memory, these sequences of spatiotemporal representations persist in conditions of altered hippocampal oscillations. The focus of this review is to disentangle the relative contribution of hippocampal oscillations from single-neuron activity in learning and memory. We first review cellular, anatomical, and physiological mechanisms underlying the generation and maintenance of hippocampal rhythms and how they contribute to memory function. We propose candidate hypotheses for how septohippocampal oscillations could support memory function while not contributing directly to hippocampal sequences. In particular, we explore how theta rhythms could coordinate the integration of upstream signals in the hippocampus to form future decisions, the relevance of such integration to downstream regions, as well as setting the stage for behavioral timescale synaptic plasticity. Finally, we leverage stimulation-based treatment in Alzheimer's disease conditions as an opportunity to assess the sufficiency of hippocampal oscillations for memory function.
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Affiliation(s)
| | | | - Sylvain Williams
- Department of Psychiatry, Douglas Mental Health Research Institute, McGill University, Montreal, QC, Canada
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Leprince E, Dard RF, Mortet S, Filippi C, Giorgi-Kurz M, Bourboulou R, Lenck-Santini PP, Picardo MA, Bocchio M, Baude A, Cossart R. Extrinsic control of the early postnatal CA1 hippocampal circuits. Neuron 2023; 111:888-902.e8. [PMID: 36608692 DOI: 10.1016/j.neuron.2022.12.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 10/18/2022] [Accepted: 12/08/2022] [Indexed: 01/07/2023]
Abstract
The adult CA1 region of the hippocampus produces coordinated neuronal dynamics with minimal reliance on its extrinsic inputs. By contrast, neonatal CA1 is tightly linked to externally generated sensorimotor activity, but the circuit mechanisms underlying early synchronous activity in CA1 remain unclear. Here, using a combination of in vivo and ex vivo circuit mapping, calcium imaging, and electrophysiological recordings in mouse pups, we show that early dynamics in the ventro-intermediate CA1 are under the mixed influence of entorhinal (EC) and thalamic (VMT) inputs. Both VMT and EC can drive internally generated synchronous events ex vivo. However, movement-related population bursts detected in vivo are exclusively driven by the EC. These differential effects on synchrony reflect the different intrahippocampal targets of these inputs. Hence, cortical and subcortical pathways act differently on the neonatal CA1, implying distinct contributions to the development of the hippocampal microcircuit and related cognitive maps.
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Affiliation(s)
- Erwan Leprince
- Aix Marseille University, INSERM, INMED (UMR1249), Turing Centre for Living systems, Marseille, France
| | - Robin F Dard
- Aix Marseille University, INSERM, INMED (UMR1249), Turing Centre for Living systems, Marseille, France
| | - Salomé Mortet
- Aix Marseille University, INSERM, INMED (UMR1249), Turing Centre for Living systems, Marseille, France
| | - Caroline Filippi
- Aix Marseille University, INSERM, INMED (UMR1249), Turing Centre for Living systems, Marseille, France
| | - Marie Giorgi-Kurz
- Aix Marseille University, INSERM, INMED (UMR1249), Turing Centre for Living systems, Marseille, France
| | - Romain Bourboulou
- Department of Cell and Developmental Biology, University College London, London, UK
| | | | - Michel A Picardo
- Aix Marseille University, INSERM, INMED (UMR1249), Turing Centre for Living systems, Marseille, France
| | - Marco Bocchio
- Aix Marseille University, INSERM, INMED (UMR1249), Turing Centre for Living systems, Marseille, France; Department of Psychology, Durham University, Durham, UK
| | - Agnès Baude
- Aix Marseille University, INSERM, INMED (UMR1249), Turing Centre for Living systems, Marseille, France
| | - Rosa Cossart
- Aix Marseille University, INSERM, INMED (UMR1249), Turing Centre for Living systems, Marseille, France.
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Pagkalos M, Chavlis S, Poirazi P. Introducing the Dendrify framework for incorporating dendrites to spiking neural networks. Nat Commun 2023; 14:131. [PMID: 36627284 PMCID: PMC9832130 DOI: 10.1038/s41467-022-35747-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 12/22/2022] [Indexed: 01/11/2023] Open
Abstract
Computational modeling has been indispensable for understanding how subcellular neuronal features influence circuit processing. However, the role of dendritic computations in network-level operations remains largely unexplored. This is partly because existing tools do not allow the development of realistic and efficient network models that account for dendrites. Current spiking neural networks, although efficient, are usually quite simplistic, overlooking essential dendritic properties. Conversely, circuit models with morphologically detailed neuron models are computationally costly, thus impractical for large-network simulations. To bridge the gap between these two extremes and facilitate the adoption of dendritic features in spiking neural networks, we introduce Dendrify, an open-source Python package based on Brian 2. Dendrify, through simple commands, automatically generates reduced compartmental neuron models with simplified yet biologically relevant dendritic and synaptic integrative properties. Such models strike a good balance between flexibility, performance, and biological accuracy, allowing us to explore dendritic contributions to network-level functions while paving the way for developing more powerful neuromorphic systems.
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Affiliation(s)
- Michalis Pagkalos
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology Hellas (FORTH), Heraklion, 70013, Greece
- Department of Biology, University of Crete, Heraklion, 70013, Greece
| | - Spyridon Chavlis
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology Hellas (FORTH), Heraklion, 70013, Greece
| | - Panayiota Poirazi
- Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology Hellas (FORTH), Heraklion, 70013, Greece.
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Cavalieri D, Angelova A, Islah A, Lopez C, Bocchio M, Bollmann Y, Baude A, Cossart R. CA1 pyramidal cell diversity is rootedin the time of neurogenesis. eLife 2021; 10:69270. [PMID: 34723790 PMCID: PMC8660020 DOI: 10.7554/elife.69270] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 10/31/2021] [Indexed: 11/18/2022] Open
Abstract
Cellular diversity supports the computational capacity and flexibility of cortical circuits. Accordingly, principal neurons at the CA1 output node of the murine hippocampus are increasingly recognized as a heterogeneous population. Their genes, molecular content, intrinsic morpho-physiology, connectivity, and function seem to segregate along the main anatomical axes of the hippocampus. Since these axes reflect the temporal order of principal cell neurogenesis, we directly examined the relationship between birthdate and CA1 pyramidal neuron diversity, focusing on the ventral hippocampus. We used a genetic fate-mapping approach that allowed tagging three groups of age-matched principal neurons: pioneer, early-, and late-born. Using a combination of neuroanatomy, slice physiology, connectivity tracing, and cFos staining in mice, we show that birthdate is a strong predictor of CA1 principal cell diversity. We unravel a subpopulation of pioneer neurons recruited in familiar environments with remarkable positioning, morpho-physiological features, and connectivity. Therefore, despite the expected plasticity of hippocampal circuits, given their role in learning and memory, the diversity of their main components is also partly determined at the earliest steps of development.
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Affiliation(s)
| | | | - Anas Islah
- INMED, INSERM Aix-Marseille University, marseille, France
| | | | | | | | - Agnès Baude
- INMED, French Institute of Health and Medical Research, Marseille, France
| | - Rosa Cossart
- INMED, French Institute of Health and Medical Research, Marseille, France
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Abstract
In mammals, the selective transformation of transient experience into stored memory occurs in the hippocampus, which develops representations of specific events in the context in which they occur. In this review, we focus on the development of hippocampal circuits and the self-organized dynamics embedded within them since the latter critically support the role of the hippocampus in learning and memory. We first discuss evidence that adult hippocampal cells and circuits are sculpted by development as early as during embryonic neurogenesis. We argue that these primary developmental programs provide a scaffold onto which later experience of the external world can be grafted. Next, we review the different sequences in the development of hippocampal cells and circuits at anatomical and functional levels. We cover a period extending from neurogenesis and migration to the appearance of phenotypic diversity within hippocampal cells, and their wiring into functional networks. We describe the progressive emergence of network dynamics in the hippocampus, from sensorimotor-driven early sharp waves to sequences of place cells tracking relational information. We outline the critical turn points and discontinuities in that developmental journey, and close by formulating open questions. We propose that rewinding the process of hippocampal development helps understand the main organization principles of memory circuits.
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Affiliation(s)
- Rosa Cossart
- Inserm, INMED, Turing Center for Living Systems, Aix Marseille University, Marseille, France
| | - Rustem Khazipov
- Inserm, INMED, Turing Center for Living Systems, Aix Marseille University, Marseille, France.,Laboratory of Neurobiology, Kazan Federal University, Kazan Russia
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Silkis IG. The Role of Hypothalamus in the Formation of Neural Representations of Object–Place Associations in the Hippocampus during Wakefulness and Paradoxical Sleep. NEUROCHEM J+ 2021. [DOI: 10.1134/s1819712421020148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Sun Q, Jiang YQ, Lu MC. Topographic heterogeneity of intrinsic excitability in mouse hippocampal CA3 pyramidal neurons. J Neurophysiol 2020; 124:1270-1284. [PMID: 32937083 DOI: 10.1152/jn.00147.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Area CA3 in the hippocampus is traditionally thought to act as a homogeneous neural circuit that is vital for spatial navigation and episodic memories. However, recent studies have revealed that CA3 pyramidal neurons in dorsal hippocampus display marked anatomic and functional heterogeneity along the proximodistal (transverse) axis. The hippocampus is also known to be functionally segregated along the dorsoventral (longitudinal) axis, with dorsal hippocampus strongly involved in spatial navigation and ventral hippocampus associated with emotion and anxiety. Surprisingly, however, relatively little is known about CA3 functional heterogeneity along the dorsoventral axis. Here, we carried out mouse-brain-slice patch-clamp recordings and morphological analyses to examine the heterogeneity of CA3 cellular properties along both proximodistal and dorsoventral axes. We find that CA3 pyramidal neurons exhibit considerable heterogeneity of somatodendritic morphology and intrinsic membrane properties, with ventral CA3 (vCA3) displaying more elaborate somatodendritic morphology, lower intrinsic excitability, smaller input resistance, greater cell capacitance, and more prominent hyperpolarization-activated current than dorsal CA3 (dCA3). Furthermore, although both dCA3 and vCA3 exhibit proximal-to-distal gradients in intrinsic properties and neuronal morphology, these proximal-to-distal gradients in vCA3 are more moderate than those in dCA3. Taken together, our results extend previous findings on the proximodistal heterogeneity of dCA3 function and uncover a complex, yet orderly, pattern of topographic organization of CA3 neuronal features that extends to multiple anatomic dimensions and may contribute to its in vivo functional diversity.NEW & NOTEWORTHY Area CA3 is a major hippocampal region that is classically thought to act as a homogeneous neural network vital for spatial navigation and episodic memories. Here, we report that CA3 pyramidal neurons exhibit marked heterogeneity of somatodendritic morphology and cellular electrical properties along both proximodistal and dorsoventral axes. These new results uncover a complex, yet orderly, pattern of topographic organization of CA3 neuronal features that may contribute to its in vivo functional diversity.
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Affiliation(s)
- Qian Sun
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Yu-Qiu Jiang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Melissa C Lu
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio
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