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Wood OWG, Walby J, Yeung JH, Ke S, Palpagama TH, Turner C, Waldvogel HJ, Faull RLM, Kwakowsky A. Alzheimer's Disease-associated Region-specific Decrease of Vesicular Glutamate Transporter Immunoreactivity inthe Medial Temporal Lobe and Superior Temporal Gyrus. Neuroscience 2024; 546:75-87. [PMID: 38552733 DOI: 10.1016/j.neuroscience.2024.03.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 03/15/2024] [Accepted: 03/25/2024] [Indexed: 04/09/2024]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder for which there are very limited treatment options. Dysfunction of the excitatory neurotransmitter system is thought to play a major role in the pathogenesis of this condition. Vesicular glutamate transporters (VGLUTs) are key to controlling the quantal release of glutamate. Thus, expressional changes in disease can have implications for aberrant neuronal activity, raising the possibility of a therapeutic target. There is no information regarding the expression of VGLUTs in the human medial temporal lobe in AD, one of the earliest and most severely affected brain regions. This study aimed to quantify and compare the layer-specific expression of VGLUT1 and VGLUT2 between control and AD cases in the hippocampus, subiculum, entorhinal cortex, and superior temporal gyrus. Free-floating fluorescent immunohistochemistry was used to label VGLUT1 and VGLUT2 in the hippocampus, subiculum, entorhinal cortex, and superior temporal gyrus. Sections were imaged using laser-scanning confocal microscopy and transporter densitometric analysis was performed. VGLUT1 density was not significantly different in AD tissue, except lower staining density observed in the dentate gyrus stratum moleculare (p = 0.0051). VGLUT2 expression was not altered in the hippocampus and entorhinal cortex of AD cases but was significantly lower in the subiculum (p = 0.015) and superior temporal gyrus (p = 0.0023). This study indicates a regionally specific vulnerability of VGLUT1 and VGLUT2 expression in the medial temporal lobe and superior temporal gyrus in AD. However, the causes and functional consequences of these disturbances need to be further explored to assess VGLUT1 and VGLUT2 as viable therapeutic targets.
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Affiliation(s)
- Oliver W G Wood
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Josh Walby
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Jason H Yeung
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Stephen Ke
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Thulani H Palpagama
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Clinton Turner
- Department of Anatomical Pathology, LabPlus, Auckland City Hospital, New Zealand
| | - Henry J Waldvogel
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Richard L M Faull
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Andrea Kwakowsky
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, New Zealand; Pharmacology and Therapeutics, School of Medicine, Galway Neuroscience Centre, University of Galway, Ireland.
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2
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Murphy TR, Amidon RF, Donohue JD, Li L, Anderson GR. Synaptic cell-adhesion molecule latrophilin-2 is differentially directed to dendritic domains of hippocampal neurons. iScience 2024; 27:108799. [PMID: 38318388 PMCID: PMC10839266 DOI: 10.1016/j.isci.2024.108799] [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: 06/07/2023] [Revised: 09/28/2023] [Accepted: 01/02/2024] [Indexed: 02/07/2024] Open
Abstract
Hippocampal pyramidal cells possess elaborate dendritic arbors with distinct domains that are targeted with input-specific synaptic sites. This synaptic arrangement is facilitated by synaptic cell-adhesion molecules that act as recognition elements to connect presynaptic and postsynaptic neurons. In this study, we investigate the organization of the synaptic recognition molecule latrophilin-2 at the surface of pyramidal neurons classified by spatial positioning and action potential firing patterns. Surveying two hippocampal neurons that highly express latrophilin-2, late-bursting CA1 pyramidal cells and early-bursting subiculum pyramidal cells, we found the molecule to be differentially positioned on their respective dendritic compartments. Investigating this latrophilin-2 positioning at the synaptic level, we found that the molecule is not present within either the pre- or postsynaptic terminal but rather is tightly coupled to synapses at a perisynaptic location. Together these findings indicate that hippocampal latrophilin-2 distribution patterning is cell-type specific, and requires multiple postsynaptic neurons for its synaptic localization.
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Affiliation(s)
- Thomas R. Murphy
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Ryan F. Amidon
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
- School of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Jordan D. Donohue
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
- Neuroscience Graduate Program, University of California, Riverside, Riverside, CA 92521, USA
| | - Libo Li
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Garret R. Anderson
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, CA 92521, USA
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3
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Lodge DJ, Elam HB, Boley AM, Donegan JJ. Discrete hippocampal projections are differentially regulated by parvalbumin and somatostatin interneurons. Nat Commun 2023; 14:6653. [PMID: 37863893 PMCID: PMC10589277 DOI: 10.1038/s41467-023-42484-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 10/12/2023] [Indexed: 10/22/2023] Open
Abstract
People with schizophrenia show hyperactivity in the ventral hippocampus (vHipp) and we have previously demonstrated distinct behavioral roles for vHipp cell populations. Here, we test the hypothesis that parvalbumin (PV) and somatostatin (SST) interneurons differentially innervate and regulate hippocampal pyramidal neurons based on their projection target. First, we use eGRASP to show that PV-positive interneurons form a similar number of synaptic connections with pyramidal cells regardless of their projection target while SST-positive interneurons preferentially target nucleus accumbens (NAc) projections. To determine if these anatomical differences result in functional changes, we used in vivo opto-electrophysiology to show that SST cells also preferentially regulate the activity of NAc-projecting cells. These results suggest vHipp interneurons differentially regulate that vHipp neurons that project to the medial prefrontal cortex (mPFC) and NAc. Characterization of these cell populations may provide potential molecular targets for the treatment schizophrenia and other psychiatric disorders associated with vHipp dysfunction.
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Affiliation(s)
- Daniel J Lodge
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center, San Antonio, TX, 78229, USA
- South Texas Veterans Health Care System, Audie L. Murphy Division, San Antonio, TX, USA
| | - Hannah B Elam
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center, San Antonio, TX, 78229, USA
- South Texas Veterans Health Care System, Audie L. Murphy Division, San Antonio, TX, USA
| | - Angela M Boley
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center, San Antonio, TX, 78229, USA
- South Texas Veterans Health Care System, Audie L. Murphy Division, San Antonio, TX, USA
| | - Jennifer J Donegan
- Department of Pharmacology and Center for Biomedical Neuroscience, University of Texas Health Science Center, San Antonio, TX, 78229, USA.
- Department of Psychiatry and Behavioral Sciences and Center for Early Life Adversity, Department of Neuroscience, Dell Medical School at the University of Texas at Austin, Austin, TX, 78712, USA.
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4
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Tzilivaki A, Tukker JJ, Maier N, Poirazi P, Sammons RP, Schmitz D. Hippocampal GABAergic interneurons and memory. Neuron 2023; 111:3154-3175. [PMID: 37467748 PMCID: PMC10593603 DOI: 10.1016/j.neuron.2023.06.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 01/04/2023] [Accepted: 06/21/2023] [Indexed: 07/21/2023]
Abstract
One of the most captivating questions in neuroscience revolves around the brain's ability to efficiently and durably capture and store information. It must process continuous input from sensory organs while also encoding memories that can persist throughout a lifetime. What are the cellular-, subcellular-, and network-level mechanisms that underlie this remarkable capacity for long-term information storage? Furthermore, what contributions do distinct types of GABAergic interneurons make to this process? As the hippocampus plays a pivotal role in memory, our review focuses on three aspects: (1) delineation of hippocampal interneuron types and their connectivity, (2) interneuron plasticity, and (3) activity patterns of interneurons during memory-related rhythms, including the role of long-range interneurons and disinhibition. We explore how these three elements, together showcasing the remarkable diversity of inhibitory circuits, shape the processing of memories in the hippocampus.
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Affiliation(s)
- Alexandra Tzilivaki
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany; Einstein Center for Neurosciences, Chariteplatz 1, 10117 Berlin, Germany; NeuroCure Cluster of Excellence, Chariteplatz 1, 10117 Berlin, Germany
| | - John J Tukker
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany; German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Nikolaus Maier
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany
| | - Panayiota Poirazi
- Foundation for Research and Technology Hellas (FORTH), Institute of Molecular Biology and Biotechnology (IMBB), N. Plastira 100, Heraklion, Crete, Greece
| | - Rosanna P Sammons
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany
| | - Dietmar Schmitz
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, Neuroscience Research Center, 10117 Berlin, Germany; Einstein Center for Neurosciences, Chariteplatz 1, 10117 Berlin, Germany; NeuroCure Cluster of Excellence, Chariteplatz 1, 10117 Berlin, Germany; German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany; Bernstein Center for Computational Neuroscience, Humboldt-Universität zu Berlin, Philippstrasse. 13, 10115 Berlin, Germany; Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle-Straße 10, 13125 Berlin, Germany.
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5
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Xiao X, Wang X, Zhu K, Li L, He Y, Zhang J, Li L, Hu H, Cui Y, Zhang J, Zheng Y. BACE1 in PV interneuron tunes hippocampal CA1 local circuits and resets priming of fear memory extinction. Mol Psychiatry 2023; 28:4151-4162. [PMID: 37452089 DOI: 10.1038/s41380-023-02176-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 06/28/2023] [Accepted: 06/30/2023] [Indexed: 07/18/2023]
Abstract
BACE1 is the rate-limiting enzyme for β-amyloid (Aβ) production and therefore is considered a prime drug target for treating Alzheimer's disease (AD). Nevertheless, the BACE1 inhibitors failed in clinical trials, even exhibiting cognitive worsening, implying that BACE1 may function in regulating cognition-relevant neural circuits. Here, we found that parvalbumin-positive inhibitory interneurons (PV INs) in hippocampal CA1 express BACE1 at a high level. We designed and developed a mouse strain with conditional knockout of BACE1 in PV neurons. The CA1 fast-spiking PV INs with BACE1 deletion exhibited an enhanced response of postsynaptic N-methyl-D-aspartate (NMDA) receptors to local stimulation on CA1 oriens, with average intrinsic electrical properties and fidelity in synaptic integration. Intriguingly, the BACE1 deletion reorganized the CA1 recurrent inhibitory motif assembled by the heterogeneous pyramidal neurons (PNs) and the adjacent fast-spiking PV INs from the superficial to the deep layer. Moreover, the conditional BACE1 deletion impaired the AMPARs-mediated excitatory transmission of deep CA1 PNs. Further rescue experiments confirmed that these phenotypes require the enzymatic activity of BACE1. Above all, the BACE1 deletion resets the priming of the fear memory extinction. Our findings suggest a neuron-specific working model of BACE1 in regulating learning and memory circuits. The study may provide a potential path of targeting BACE1 and NMDAR together to circumvent cognitive worsening due to a single application of BACE1 inhibitor in AD patients.
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Affiliation(s)
- Xuansheng Xiao
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
- Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
| | - Xiaotong Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
- Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
| | - Ke Zhu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
- Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
| | - Lijuan Li
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
- Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
| | - Ying He
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
- Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
| | - Jinglan Zhang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Linying Li
- Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
- Department of Neurobiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Hanning Hu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
- Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
| | - Yanqiu Cui
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Jianliang Zhang
- Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China
- Department of Neurobiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China
| | - Yan Zheng
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, China.
- Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, China.
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6
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Nelson ED, Maynard KR, Nicholas KR, Tran MN, Divecha HR, Collado-Torres L, Hicks SC, Martinowich K. Activity-regulated gene expression across cell types of the mouse hippocampus. Hippocampus 2023; 33:1009-1027. [PMID: 37226416 PMCID: PMC11129873 DOI: 10.1002/hipo.23548] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 04/19/2023] [Accepted: 05/06/2023] [Indexed: 05/26/2023]
Abstract
Activity-regulated gene (ARG) expression patterns in the hippocampus (HPC) regulate synaptic plasticity, learning, and memory, and are linked to both risk and treatment responses for many neuropsychiatric disorders. The HPC contains discrete classes of neurons with specialized functions, but cell type-specific activity-regulated transcriptional programs are not well characterized. Here, we used single-nucleus RNA-sequencing (snRNA-seq) in a mouse model of acute electroconvulsive seizures (ECS) to identify cell type-specific molecular signatures associated with induced activity in HPC neurons. We used unsupervised clustering and a priori marker genes to computationally annotate 15,990 high-quality HPC neuronal nuclei from N = 4 mice across all major HPC subregions and neuron types. Activity-induced transcriptomic responses were divergent across neuron populations, with dentate granule cells being particularly responsive to activity. Differential expression analysis identified both upregulated and downregulated cell type-specific gene sets in neurons following ECS. Within these gene sets, we identified enrichment of pathways associated with varying biological processes such as synapse organization, cellular signaling, and transcriptional regulation. Finally, we used matrix factorization to reveal continuous gene expression patterns differentially associated with cell type, ECS, and biological processes. This work provides a rich resource for interrogating activity-regulated transcriptional responses in HPC neurons at single-nuclei resolution in the context of ECS, which can provide biological insight into the roles of defined neuronal subtypes in HPC function.
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Affiliation(s)
- Erik D. Nelson
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, 21205, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Kristen R. Maynard
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, 21205, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Kyndall R. Nicholas
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, 21205, USA
| | - Matthew N Tran
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, 21205, USA
| | - Heena R. Divecha
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, 21205, USA
| | - Leonardo Collado-Torres
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, 21205, USA
| | - Stephanie C. Hicks
- Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
| | - Keri Martinowich
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD, 21205, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- The Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, 21205
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7
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Boxer EE, Kim J, Dunn B, Aoto J. Ventral Subiculum Inputs to Nucleus Accumbens Medial Shell Preferentially Innervate D2R Medium Spiny Neurons and Contain Calcium Permeable AMPARs. J Neurosci 2023; 43:1166-1177. [PMID: 36609456 PMCID: PMC9962776 DOI: 10.1523/jneurosci.1907-22.2022] [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: 10/08/2022] [Revised: 12/09/2022] [Accepted: 12/29/2022] [Indexed: 01/09/2023] Open
Abstract
Ventral subiculum (vSUB) is the major output region of ventral hippocampus (vHIPP) and sends major projections to nucleus accumbens medial shell (NAcMS). Hyperactivity of the vSUB-NAcMS circuit is associated with substance use disorders and the modulation of vSUB activity alters drug seeking and drug reinstatement behavior in rodents. However, to the best of our knowledge, the cell type-specific connectivity and synaptic transmission properties of the vSUB-NAcMS circuit have never been directly examined. Instead, previous functional studies have focused on total ventral hippocampal (vHIPP) output to NAcMS without distinguishing vSUB from other subregions of vHIPP, including ventral CA1 (vCA1). Using ex vivo electrophysiology, we systematically characterized the vSUB-NAcMS circuit with cell type- and synapse-specific resolution in male and female mice and found that vSUB output to dopamine receptor type-1 (D1R) and type-2 (D2R) expressing medium spiny neurons (MSNs) displays a functional connectivity bias for D2R MSNs. Furthermore, we found that vSUB-D1R and vSUB-D2R MSN synapses contain calcium-permeable AMPA receptors in drug-naive mice. Finally, we find that, distinct from other glutamatergic inputs, cocaine exposure selectively induces plasticity at vSUB-D2R synapses. Importantly, we directly compared vSUB and vCA1 output to NAcMS and found that vSUB synapses are functionally distinct and that vCA1 output recapitulated the synaptic properties previously ascribed to vHIPP. Our work highlights the need to consider the contributions of individual subregions of vHIPP to substance use disorders and represents an important first step toward understanding how the vSUB-NAcMS circuit contributes to the etiologies that underlie substance use disorders.SIGNIFICANCE STATEMENT Inputs to nucleus accumbens (NAc) dopamine receptor type 1 (D1R) and D2R medium spiny neurons (MSNs) are critically involved in reward seeking behavior. Ventral subiculum (vSUB) provides robust synaptic input to nucleus accumbens medial shell (NAcMS) and activity of this circuit is linked to substance use disorders. Despite the importance of the vSUB to nucleus accumbens circuit, the functional connectivity and synaptic transmission properties have not been tested. Here, we systematically interrogated these properties and found that basal connectivity and drug-induced plasticity are biased for D2R medium spiny neurons. Overall, we demonstrate that this circuit is distinct from synaptic inputs from other brain regions, which helps to explain how vSUB dysfunction contributes to the etiologies that underlie substance use disorders.
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Affiliation(s)
- Emma E Boxer
- University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - JungMin Kim
- University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - Brett Dunn
- University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - Jason Aoto
- University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
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8
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Lippmann K, Klaft ZJ, Salar S, Hollnagel JO, Valero M, Maslarova A. Status epilepticus induces chronic silencing of burster and dominance of regular firing neurons during sharp wave-ripples in the mouse subiculum. Neurobiol Dis 2022; 175:105929. [DOI: 10.1016/j.nbd.2022.105929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/08/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022] Open
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9
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Lee SM, Seol JM, Lee I. Subicular neurons represent multiple variables of a hippocampal-dependent task by using theta rhythm. PLoS Biol 2022; 20:e3001546. [PMID: 35100261 PMCID: PMC8830791 DOI: 10.1371/journal.pbio.3001546] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 02/10/2022] [Accepted: 01/18/2022] [Indexed: 01/31/2023] Open
Abstract
The subiculum is positioned at a critical juncture at the interface of the hippocampus with the rest of the brain. However, the exact roles of the subiculum in most hippocampal-dependent memory tasks remain largely unknown. One obstacle to make comparisons of neural firing patterns between the subiculum and hippocampus is the broad firing fields of the subicular cells. Here, we used spiking phases in relation to theta rhythm to parse the broad firing field of a subicular neuron into multiple subfields to find the unique functional contribution of the subiculum while male rats performed a hippocampal-dependent visual scene memory task. Some of the broad firing fields of the subicular neurons were successfully divided into multiple subfields similar to those in the CA1 by using the theta phase precession cycle. The new paradigm significantly improved the detection of task-relevant information in subicular cells without affecting the information content represented by CA1 cells. Notably, we found that multiple fields of a single subicular neuron, unlike those in the CA1, carried heterogeneous task-related information such as visual context and choice response. Our findings suggest that the subicular cells integrate multiple task-related factors by using theta rhythm to associate environmental context with action. The subiculum is positioned at the interface between the hippocampus and the rest of the brain, but what is its role in hippocampal-dependent memory tasks? This neurophysiological study provides novel insights into how the subiculum represents multiple cognitive variables by using both rate and temporal codes.
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Affiliation(s)
- Su-Min Lee
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
| | - Jae-Min Seol
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
| | - Inah Lee
- Department of Brain and Cognitive Sciences, Seoul National University, Seoul, Korea
- * E-mail:
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10
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Boxer EE, Seng C, Lukacsovich D, Kim J, Schwartz S, Kennedy MJ, Földy C, Aoto J. Neurexin-3 defines synapse- and sex-dependent diversity of GABAergic inhibition in ventral subiculum. Cell Rep 2021; 37:110098. [PMID: 34879268 PMCID: PMC8763380 DOI: 10.1016/j.celrep.2021.110098] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 08/09/2021] [Accepted: 11/15/2021] [Indexed: 11/24/2022] Open
Abstract
Ventral subiculum (vSUB) is integral to the regulation of stress and reward; however, the intrinsic connectivity and synaptic properties of the inhibitory local circuit are poorly understood. Neurexin-3 (Nrxn3) is highly expressed in hippocampal inhibitory neurons, but its function at inhibitory synapses has remained elusive. Using slice electrophysiology, imaging, and single-cell RNA sequencing, we identify multiple roles for Nrxn3 at GABAergic parvalbumin (PV) interneuron synapses made onto vSUB regular-spiking (RS) and burst-spiking (BS) principal neurons. Surprisingly, we find that intrinsic connectivity of vSUB and synaptic function of Nrxn3 in vSUB are sexually dimorphic. We reveal that PVs make preferential contact with RS neurons in male mice, but BS neurons in female mice. Furthermore, we determine that despite comparable Nrxn3 isoform expression in male and female PV neurons, Nrxn3 knockout impairs synapse density, postsynaptic strength, and inhibitory postsynaptic current (IPSC) amplitude at PV-RS synapses in males, but enhances presynaptic release and IPSC amplitude in females.
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Affiliation(s)
- Emma E Boxer
- University of Colorado Anschutz, Department of Pharmacology, Aurora, CO 80045, USA; Neuroscience Graduate Program, University of Colorado Anschutz, Aurora, CO 80045, USA
| | - Charlotte Seng
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Science, University of Zurich, 8057 Zurich, Switzerland
| | - David Lukacsovich
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Science, University of Zurich, 8057 Zurich, Switzerland
| | - JungMin Kim
- University of Colorado Anschutz, Department of Pharmacology, Aurora, CO 80045, USA; Neuroscience Graduate Program, University of Colorado Anschutz, Aurora, CO 80045, USA
| | - Samantha Schwartz
- University of Colorado Anschutz, Department of Pharmacology, Aurora, CO 80045, USA
| | - Matthew J Kennedy
- University of Colorado Anschutz, Department of Pharmacology, Aurora, CO 80045, USA
| | - Csaba Földy
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Science, University of Zurich, 8057 Zurich, Switzerland
| | - Jason Aoto
- University of Colorado Anschutz, Department of Pharmacology, Aurora, CO 80045, USA.
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11
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AlSubaie R, Wee RWS, Ritoux A, Mishchanchuk K, Passlack J, Regester D, MacAskill AF. Control of parallel hippocampal output pathways by amygdalar long-range inhibition. eLife 2021; 10:e74758. [PMID: 34845987 PMCID: PMC8654375 DOI: 10.7554/elife.74758] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 11/29/2021] [Indexed: 12/14/2022] Open
Abstract
Projections from the basal amygdala (BA) to the ventral hippocampus (vH) are proposed to provide information about the rewarding or threatening nature of learned associations to support appropriate goal-directed and anxiety-like behaviour. Such behaviour occurs via the differential activity of multiple, parallel populations of pyramidal neurons in vH that project to distinct downstream targets, but the nature of BA input and how it connects with these populations is unclear. Using channelrhodopsin-2-assisted circuit mapping in mice, we show that BA input to vH consists of both excitatory and inhibitory projections. Excitatory input specifically targets BA- and nucleus accumbens-projecting vH neurons and avoids prefrontal cortex-projecting vH neurons, while inhibitory input preferentially targets BA-projecting neurons. Through this specific connectivity, BA inhibitory projections gate place-value associations by controlling the activity of nucleus accumbens-projecting vH neurons. Our results define a parallel excitatory and inhibitory projection from BA to vH that can support goal-directed behaviour.
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Affiliation(s)
- Rawan AlSubaie
- Department of Neuroscience, Physiology and Pharmacology, University College LondonLondonUnited Kingdom
| | - Ryan WS Wee
- Department of Neuroscience, Physiology and Pharmacology, University College LondonLondonUnited Kingdom
| | - Anne Ritoux
- Department of Neuroscience, Physiology and Pharmacology, University College LondonLondonUnited Kingdom
| | - Karyna Mishchanchuk
- Department of Neuroscience, Physiology and Pharmacology, University College LondonLondonUnited Kingdom
| | - Jessica Passlack
- Department of Neuroscience, Physiology and Pharmacology, University College LondonLondonUnited Kingdom
| | - Daniel Regester
- Department of Neuroscience, Physiology and Pharmacology, University College LondonLondonUnited Kingdom
| | - Andrew F MacAskill
- Department of Neuroscience, Physiology and Pharmacology, University College LondonLondonUnited Kingdom
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12
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Ross TW, Easton A. The Hippocampal Horizon: Constructing and Segmenting Experience for Episodic Memory. Neurosci Biobehav Rev 2021; 132:181-196. [PMID: 34826509 DOI: 10.1016/j.neubiorev.2021.11.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 12/29/2022]
Abstract
How do we recollect specific events that have occurred during continuous ongoing experience? There is converging evidence from non-human animals that spatially modulated cellular activity of the hippocampal formation supports the construction of ongoing events. On the other hand, recent human oriented event cognition models have outlined that our experience is segmented into discrete units, and that such segmentation can operate on shorter or longer timescales. Here, we describe a unification of how these dynamic physiological mechanisms of the hippocampus relate to ongoing externally and internally driven event segmentation, facilitating the demarcation of specific moments during experience. Our cross-species interdisciplinary approach offers a novel perspective in the way we construct and remember specific events, leading to the generation of many new hypotheses for future research.
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Affiliation(s)
- T W Ross
- Department of Psychology, Durham University, South Road, Durham, DH1 3LE, United Kingdom; Centre for Learning and Memory Processes, Durham University, United Kingdom.
| | - A Easton
- Department of Psychology, Durham University, South Road, Durham, DH1 3LE, United Kingdom; Centre for Learning and Memory Processes, Durham University, United Kingdom
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13
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Beerens S, Vroman R, Webster JF, Wozny C. Probing subicular inputs to the medial prefrontal cortex. iScience 2021; 24:102856. [PMID: 34381980 PMCID: PMC8333156 DOI: 10.1016/j.isci.2021.102856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 04/14/2021] [Accepted: 07/09/2021] [Indexed: 11/19/2022] Open
Abstract
The hippocampal formation is anatomically and functionally divided into a dorsal and a ventral part, being involved in processing cognitive tasks and emotional stimuli, respectively. The ventral subiculum as part of the hippocampal formation projects to the medial prefrontal cortex (mPFC), but only very little is known about connections arising from the dorsal SUB (dSUB). Here, we investigate the dSUB to mPFC connectivity in acute brain slices using electrophysiology and optogenetics. We show that the anterior cingulate cortex (ACC) is the main target of dorsal subicular projections to the mPFC, with no preference between excitatory or inhibitory neurons. In addition to superficial neurons in the ACC, the prelimbic and infralimbic PFC are also targeted by subicular fibers. Thus, these novel region- and layer-specific connections between the dSUB and the prefrontal cortices challenge existing anatomical data and refine the hippocampocortical wiring diagram.
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Affiliation(s)
- Sanne Beerens
- Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Rozan Vroman
- Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Jack F. Webster
- Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Christian Wozny
- Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
- MSH Medical School Hamburg, Faculty of Medicine, Medical University, Hamburg, Germany
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14
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Vasnik S, Sikdar SK. Cholinergic receptor-independent modulation of intrinsic resonance in the rat subiculum neurons through inhibition of hyperpolarization-activated cyclic nucleotide-gated channels. Acta Physiol (Oxf) 2021; 231:e13603. [PMID: 33332740 DOI: 10.1111/apha.13603] [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: 09/14/2020] [Revised: 11/22/2020] [Accepted: 12/11/2020] [Indexed: 11/27/2022]
Abstract
AIM Acetylcholine release is vital in the pacing of theta rhythms in the hippocampus. The subiculum is the output region of the hippocampus with different neuronal subtypes that generate theta oscillations during arousal and rapid eye movement sleep. The combination of intrinsic resonance in the hippocampal neurons and the periodic excitation of hippocampal excitatory and inhibitory neurons by cholinergic pathway drives theta oscillations. However, the acetylcholine mediated effect on intrinsic subthreshold resonance generating hyperpolarization-activated cyclic nucleotide-gated current, Ih of subicular neurons is unexplored. We studied the acetylcholine receptor-independent effect of cholinergic agents on the intrinsic properties of subiculum principal neurons and the underlying mechanism. METHODS We bath perfused acetylcholine or nicotine on rat brain slices in the presence of synaptic blockers. The physiological effect was studied by cholinergic fibres stimulation and electrophysiological recordings under whole-cell mode of subiculum neurons using septohippocampal sections. RESULTS Exogenously applied acetylcholine in the presence of atropine affected two groups of subicular neurons differently. Acetylcholine reduced the resonance frequency and Ih in bursting neurons, whereas these properties were unaffected in regular firing neurons. Subsequently, the endogenously released acetylcholine by stimulation showed a selective suppressive effect on Ih , sag, and resonance in burst firing among the two excitatory neurons. Nicotine suppressed the Ih amplitude in burst firing neurons, which was evident by decreased sag amplitude and resonance frequency and increased excitability. CONCLUSION Our study suggests cell type-specific acetylcholine receptor-independent shift in resonance frequency by partially inhibiting HCN current during high cholinergic inputs.
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Affiliation(s)
- Sonali Vasnik
- Molecular Biophysics Unit Indian Institute of Science Bangalore India
| | - Sujit K. Sikdar
- Molecular Biophysics Unit Indian Institute of Science Bangalore India
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15
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Wee RWS, MacAskill AF. Biased Connectivity of Brain-wide Inputs to Ventral Subiculum Output Neurons. Cell Rep 2021; 30:3644-3654.e6. [PMID: 32187537 PMCID: PMC7090382 DOI: 10.1016/j.celrep.2020.02.093] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/17/2020] [Accepted: 02/25/2020] [Indexed: 01/16/2023] Open
Abstract
The ventral subiculum (vS) of the mouse hippocampus coordinates diverse behaviors through heterogeneous populations of pyramidal neurons that project to multiple distinct downstream regions. Each of these populations of neurons is proposed to integrate a unique combination of thousands of local and long-range synaptic inputs, but the extent to which this occurs remains unknown. To address this, we employ monosynaptic rabies tracing to study the input-output relationship of vS neurons. Analysis of brain-wide inputs reveals quantitative input differences that could be explained by a combination of both the identity of the downstream target and the spatial location of the postsynaptic neurons within vS. These results support a model of combined topographical and output-defined connectivity of vS inputs. Overall, we reveal prominent heterogeneity in brain-wide inputs to the vS parallel output circuitry, providing a basis for the selective control of individual projections during behavior.
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Affiliation(s)
- Ryan W S Wee
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Andrew F MacAskill
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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16
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Bant JS, Hardcastle K, Ocko SA, Giocomo LM. Topography in the Bursting Dynamics of Entorhinal Neurons. Cell Rep 2021; 30:2349-2359.e7. [PMID: 32075768 DOI: 10.1016/j.celrep.2020.01.057] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 11/28/2019] [Accepted: 01/17/2020] [Indexed: 12/18/2022] Open
Abstract
Medial entorhinal cortex contains neural substrates for representing space. These substrates include grid cells that fire in repeating locations and increase in scale progressively along the dorsal-to-ventral entorhinal axis, with the physical distance between grid firing nodes increasing from tens of centimeters to several meters in rodents. Whether the temporal scale of grid cell spiking dynamics shows a similar dorsal-to-ventral organization remains unknown. Here, we report the presence of a dorsal-to-ventral gradient in the temporal spiking dynamics of grid cells in behaving mice. This gradient in bursting supports the emergence of a dorsal grid cell population with a high signal-to-noise ratio. In vitro recordings combined with a computational model point to a role for gradients in non-inactivating sodium conductances in supporting the bursting gradient in vivo. Taken together, these results reveal a complementary organization in the temporal and intrinsic properties of entorhinal cells.
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Affiliation(s)
- Jason S Bant
- Department of Neurobiology, Stanford University School of Medicine, Stanford CA 94305, USA
| | - Kiah Hardcastle
- Department of Neurobiology, Stanford University School of Medicine, Stanford CA 94305, USA
| | - Samuel A Ocko
- Department of Applied Physics, Stanford University, Stanford CA 94305, USA
| | - Lisa M Giocomo
- Department of Neurobiology, Stanford University School of Medicine, Stanford CA 94305, USA.
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17
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Fei F, Wang X, Wang Y, Chen Z. Dissecting the role of subiculum in epilepsy: Research update and translational potential. Prog Neurobiol 2021; 201:102029. [PMID: 33636224 DOI: 10.1016/j.pneurobio.2021.102029] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 01/12/2021] [Accepted: 02/21/2021] [Indexed: 11/25/2022]
Abstract
The subiculum serves as the strategic core output of the hippocampus, through which neural activity exits the hippocampal proper and targets the entorhinal cortex and other more distant subcortical and cortical areas. The past decade has witnessed a growing interest in the subiculum, owing to discoveries revealing its critical role in regulating many physiological and pathophysiological processes. Notably, accumulating evidence from both clinical and experimental studies suggests that the subiculum plays a vital role in seizure initiation and propagation, in epilepsy. In this review, we briefly describe the structure and connectivity of the subiculum and then summarize the molecular and cellular mechanisms in the subiculum underlying the epileptic brain, in both epilepsy patients and animal models. Next, we review some translational approaches targeting the malfunctioned subiculum to treat epilepsy. Finally, we pose open questions for future research in the subiculum and their clinical translation challenges.
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Affiliation(s)
- Fan Fei
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Xia Wang
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Yi Wang
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China; Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Zhong Chen
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China; Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China; Epilepsy Center, Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
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18
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Poulter S, Lee SA, Dachtler J, Wills TJ, Lever C. Vector trace cells in the subiculum of the hippocampal formation. Nat Neurosci 2021; 24:266-275. [PMID: 33349710 PMCID: PMC7116739 DOI: 10.1038/s41593-020-00761-w] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 11/16/2020] [Indexed: 11/12/2022]
Abstract
Successfully navigating in physical or semantic space requires a neural representation of allocentric (map-based) vectors to boundaries, objects and goals. Cognitive processes such as path-planning and imagination entail the recall of vector representations, but evidence of neuron-level memory for allocentric vectors has been lacking. Here, we describe a novel neuron type, vector trace cell (VTC), whose firing generates a new vector field when a cue is encountered and a 'trace' version of that field for hours after cue removal. VTCs are concentrated in subiculum, distal to CA1. Compared to non-trace cells, VTCs fire at further distances from cues and exhibit earlier-going shifts in preferred theta phase in response to newly introduced cues, which demonstrates a theta-linked neural substrate for memory encoding. VTCs suggest a vector-based model of computing spatial relationships between an agent and multiple spatial objects, or between different objects, freed from the constraints of direct perception of those objects.
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Affiliation(s)
| | - Sang Ah Lee
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | | | - Thomas J Wills
- Department of Cell and Developmental Biology, UCL, London, UK.
| | - Colin Lever
- Psychology Department, Durham University, Durham, UK.
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19
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Lévesque M, Avoli M. The subiculum and its role in focal epileptic disorders. Rev Neurosci 2020; 32:249-273. [PMID: 33661586 DOI: 10.1515/revneuro-2020-0091] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 09/29/2020] [Indexed: 01/07/2023]
Abstract
The subicular complex (hereafter referred as subiculum), which is reciprocally connected with the hippocampus and rhinal cortices, exerts a major control on hippocampal outputs. Over the last three decades, several studies have revealed that the subiculum plays a pivotal role in learning and memory but also in pathological conditions such as mesial temporal lobe epilepsy (MTLE). Indeed, subicular networks actively contribute to seizure generation and this structure is relatively spared from the cell loss encountered in this focal epileptic disorder. In this review, we will address: (i) the functional properties of subicular principal cells under normal and pathological conditions; (ii) the subiculum role in sustaining seizures in in vivo models of MTLE and in in vitro models of epileptiform synchronization; (iii) its presumptive role in human MTLE; and (iv) evidence underscoring the relationship between subiculum and antiepileptic drug effects. The studies reviewed here reinforce the view that the subiculum represents a limbic area with relevant, as yet unexplored, roles in focal epilepsy.
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Affiliation(s)
- Maxime Lévesque
- Departments of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, 3801 University Street, Montreal, H3A 2B4Québec, Canada
| | - Massimo Avoli
- Departments of Neurology, Neurosurgery, and Physiology, Montreal Neurological Institute-Hospital, McGill University, 3801 University Street, Montreal, H3A 2B4Québec, Canada
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20
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Interaction of neuronal and network mechanisms on firing propagation in a feedforward network. Neurocomputing 2020. [DOI: 10.1016/j.neucom.2020.05.088] [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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21
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Tukker JJ, Beed P, Schmitz D, Larkum ME, Sachdev RNS. Up and Down States and Memory Consolidation Across Somatosensory, Entorhinal, and Hippocampal Cortices. Front Syst Neurosci 2020; 14:22. [PMID: 32457582 PMCID: PMC7227438 DOI: 10.3389/fnsys.2020.00022] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/03/2020] [Indexed: 01/01/2023] Open
Abstract
In the course of a day, brain states fluctuate, from conscious awake information-acquiring states to sleep states, during which previously acquired information is further processed and stored as memories. One hypothesis is that memories are consolidated and stored during "offline" states such as sleep, a process thought to involve transfer of information from the hippocampus to other cortical areas. Up and Down states (UDS), patterns of activity that occur under anesthesia and sleep states, are likely to play a role in this process, although the nature of this role remains unclear. Here we review what is currently known about these mechanisms in three anatomically distinct but interconnected cortical areas: somatosensory cortex, entorhinal cortex, and the hippocampus. In doing so, we consider the role of this activity in the coordination of "replay" during sleep states, particularly during hippocampal sharp-wave ripples. We conclude that understanding the generation and propagation of UDS may provide key insights into the cortico-hippocampal dialogue linking archi- and neocortical areas during memory formation.
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Affiliation(s)
- John J Tukker
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Neuroscience Research Center, Berlin, Germany.,German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Prateep Beed
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Neuroscience Research Center, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
| | - Dietmar Schmitz
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Neuroscience Research Center, Berlin, Germany.,German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,Berlin Institute of Health, Berlin, Germany.,Cluster of Excellence NeuroCure, Berlin, Germany.,Einstein Center for Neurosciences Berlin, Berlin, Germany
| | - Matthew E Larkum
- Cluster of Excellence NeuroCure, Berlin, Germany.,Einstein Center for Neurosciences Berlin, Berlin, Germany.,Institut für Biologie, Humboldt Universität, Berlin, Germany
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22
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Nitzan N, McKenzie S, Beed P, English DF, Oldani S, Tukker JJ, Buzsáki G, Schmitz D. Propagation of hippocampal ripples to the neocortex by way of a subiculum-retrosplenial pathway. Nat Commun 2020; 11:1947. [PMID: 32327634 PMCID: PMC7181800 DOI: 10.1038/s41467-020-15787-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 03/27/2020] [Indexed: 02/07/2023] Open
Abstract
Bouts of high frequency activity known as sharp wave ripples (SPW-Rs) facilitate communication between the hippocampus and neocortex. However, the paths and mechanisms by which SPW-Rs broadcast their content are not well understood. Due to its anatomical positioning, the granular retrosplenial cortex (gRSC) may be a bridge for this hippocampo-cortical dialogue. Using silicon probe recordings in awake, head-fixed mice, we show the existence of SPW-R analogues in gRSC and demonstrate their coupling to hippocampal SPW-Rs. gRSC neurons reliably distinguished different subclasses of hippocampal SPW-Rs according to ensemble activity patterns in CA1. We demonstrate that this coupling is brain state-dependent, and delineate a topographically-organized anatomical pathway via VGlut2-expressing, bursty neurons in the subiculum. Optogenetic stimulation or inhibition of bursty subicular cells induced or reduced responses in superficial gRSC, respectively. These results identify a specific path and underlying mechanisms by which the hippocampus can convey neuronal content to the neocortex during SPW-Rs.
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Affiliation(s)
- Noam Nitzan
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Neuroscience Research Center, Berlin, Germany
| | - Sam McKenzie
- Neuroscience Institute and Department of Neurology New York University Langone Medical Center, New York, NY, 10016, USA
| | - Prateep Beed
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Neuroscience Research Center, Berlin, Germany
| | - Daniel Fine English
- Neuroscience Institute and Department of Neurology New York University Langone Medical Center, New York, NY, 10016, USA
- School of Neuroscience, College of Science, Virginia Tech, VA, 24061, USA
| | - Silvia Oldani
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Neuroscience Research Center, Berlin, Germany
- Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - John J Tukker
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Neuroscience Research Center, Berlin, Germany
- Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - György Buzsáki
- Neuroscience Institute and Department of Neurology New York University Langone Medical Center, New York, NY, 10016, USA.
- Center for Neural Science, New York University, New York, NY, 10016, USA.
| | - Dietmar Schmitz
- Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Neuroscience Research Center, Berlin, Germany.
- Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.
- Cluster of Excellence NeuroCure, Berlin, Germany.
- Einstein Center for Neurosciences, Berlin, Germany.
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23
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Fiske MP, Anstötz M, Welty LJ, Maccaferri G. The intrinsic cell type-specific excitatory connectivity of the developing mouse subiculum is sufficient to generate synchronous epileptiform activity. J Physiol 2020; 598:1965-1985. [PMID: 32119127 DOI: 10.1113/jp279561] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 02/18/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The activity of local excitatory circuits of the subiculum has been suggested to be involved in the initiation of pathological activity in epileptic patients and experimental animal models of temporal lobe epilepsy. We have taken advantage of multimodal techniques to classify subicular cells in distinct subclasses and have investigated their morphofunctional properties and connectivity in vitro. Our results indicate that local subicular excitatory circuits are connected in a cell type-specific fashion and that synapses are preferentially established on basal vs. apical dendrites. We show that local excitatory circuits, isolated from extrasubicular inputs and pharmacologically disinhibited, are sufficient to initiate synchronous epileptiform activity in vitro. In conclusion, this work provides a high-resolution description of local excitatory circuits of the subiculum and highlights their mechanistic involvement in the generation of pathological activity. ABSTRACT The subiculum has been suggested to be involved in the initiation of pathological discharges in human patients and animal models of temporal lobe epilepsy. Although converging evidence has revealed the existence of functional diversity within its principal neurons, much less attention has been devoted to its intrinsic connectivity and whether its local excitatory circuits are sufficient to generate epileptiform activity. Here, we have directly addressed these two key points in mouse subicular slices. First, using multivariate techniques, we have distinguished two groups of principal cells, which we have termed type 1 and type 2. These subgroups roughly overlap with what were classically indicated as regular and bursting cells, and showed differences in the extension and complexity of their apical dendrites. Functional connectivity was found both between similar (homotypic) and different (heterotypic) types of cells, with a marked asymmetry within heterotypic pairs. Unitary excitatory postsynaptic potentials (uEPSPs) revealed a high degree of variability both in amplitude, failure rate, rise time and half-width. Post hoc analysis of functionally connected pairs suggested that the observed uEPSPs were mediated by few contact sites, predominantly located on the basal dendrites. When surgically isolated from extrasubicular excitatory afferents, pharmacologically disinhibited subicular slices generated hyper-synchronous discharges. Thus, we conclude that local subicular excitatory circuits, connected according to cell type-specific rules, are sufficient to promote epileptiform activity. This conclusion fits well with a previous suggestion that local subicular events, purely mediated by excitatory connections, may underlie the pre-ictal discharges that govern interictal-ictal transitions.
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Affiliation(s)
- Michael Patrick Fiske
- Northwestern University Interdepartmental PhD Program & Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Max Anstötz
- Northwestern University Interdepartmental PhD Program & Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Leah J Welty
- Biostatistics Collaboration Center, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Gianmaria Maccaferri
- Northwestern University Interdepartmental PhD Program & Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
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24
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Bartsch JC, Behr J. Noncanonical, Dopamine-Dependent Long-Term Potentiation at Hippocampal Output Synapses in a Rodent Model of First-Episode Psychosis. Front Mol Neurosci 2020; 13:55. [PMID: 32317931 PMCID: PMC7146052 DOI: 10.3389/fnmol.2020.00055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 03/17/2020] [Indexed: 12/16/2022] Open
Abstract
Cognitive deficits and positive symptoms in schizophrenia have both been linked to hippocampal dysfunction. Recently, subregion-specific aberrant and maladaptive hippocampal synaptic plasticity has been suggested as one of the mechanistic underpinnings. The subiculum is the final output hub of the hippocampus and orchestrates hippocampal information transfer to other brain regions. While most CA1 pyramidal neurons show regular-spiking behavior, subicular output neurons comprise bursting and regular-firing pyramidal cells. These two cell types target different brain regions and express unique forms of synaptic plasticity. Here, we used a single systemic application of the noncompetitive glutamatergic N-methyl-D-aspartate receptor (NMDAR) antagonist MK-801 to model first-episode psychosis in rats and studied long-term potentiation (LTP) in subicular regular-firing cells in acute hippocampal slices. Previously, we have reported a facilitation of a presynaptic, late-onset LTP in subicular bursting pyramidal cells after systemic NMDAR antagonism. Here, we show that single systemic NMDAR antagonist application also facilitates the induction of a noncanonical, but postsynaptic NMDAR-independent LTP in ventral subicular but not in CA1 regular-firing pyramidal cells. This form of LTP was dependent on D1/D5 dopamine receptor activation. Activation of D1/D5 dopamine receptors by a specific agonist mimicked and occluded LTP induced by electrical high-frequency stimulation (HFS). Furthermore, our results indicate that this form of LTP relies on postsynaptic Ca2+ signaling and requires the activation of protein kinase A. Considering the pivotal role of the subiculum as information gatekeeper between the hippocampus and other brain regions, this aberrant LTP in ventral subicular regular-firing neurons is expected to interfere with physiological hippocampal output processing and might thereby contribute to hippocampal dysfunction in psychotic events.
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Affiliation(s)
- Julia C Bartsch
- Department of Psychiatry and Psychotherapy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Joachim Behr
- Department of Psychiatry and Psychotherapy, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatic Medicine, Brandenburg Medical School, Neuruppin, Germany
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Angulo SL, Henzi T, Neymotin SA, Suarez MD, Lytton WW, Schwaller B, Moreno H. Amyloid pathology-produced unexpected modifications of calcium homeostasis in hippocampal subicular dendrites. Alzheimers Dement 2020; 16:251-261. [PMID: 31668966 DOI: 10.1016/j.jalz.2019.07.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
INTRODUCTION Alzheimer's disease (AD) is linked to neuronal calcium dyshomeostasis, which is associated with network hyperexcitability. Decreased expression of the calcium-binding protein cal- bindin-D28K (CB) might be a susceptibility factor for AD. The subiculum is affected early in AD, for unknown reasons. METHODS In AD, CB knock-out and control mice fluorescence Ca2+ imaging combined with patch clamp were used to characterize Ca2+ dynamics, resting Ca2+ , and Ca2+ -buffering capacity in subicular neurons. CB expression levels in wild-type and AD mice were also analyzed. RESULTS The subiculum and dentate gyrus of wild-type mice showed age-related decline in CB expression not observed in AD mice. Resting Ca2+ and Ca2+ -buffering capacity was increased in aged AD mice subicular dendrites. Modeling suggests that AD calcium changes can be explained by alterations of Ca2+ extrusion pumps rather than by buffers. DISCUSSION Overall, abnormal Ca2+ homeostasis in AD has an age dependency that comprises multiple mechanisms, including compensatory processes.
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Affiliation(s)
- Sergio L Angulo
- Departments of Neurology and Physiology/Pharmacology, The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Medical Center, Brooklyn, NY, USA
| | - Thomas Henzi
- Anatomy, Department of Medicine, University of Fribourg, Fribourg, Switzerland
| | - Samuel A Neymotin
- Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Manuel D Suarez
- Departments of Neurology and Physiology/Pharmacology, The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Medical Center, Brooklyn, NY, USA
| | - William W Lytton
- Departments of Neurology and Physiology/Pharmacology, The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Medical Center, Brooklyn, NY, USA
- Kings County Hospital, Brooklyn, NY, USA
| | - Beat Schwaller
- Anatomy, Department of Medicine, University of Fribourg, Fribourg, Switzerland
| | - Herman Moreno
- Departments of Neurology and Physiology/Pharmacology, The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Medical Center, Brooklyn, NY, USA
- Kings County Hospital, Brooklyn, NY, USA
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26
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Ishihara Y, Fukuda T, Sato F. Internal structure of the rat subiculum characterized by diverse immunoreactivities and septotemporal differences. Neurosci Res 2020; 150:17-28. [DOI: 10.1016/j.neures.2019.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 12/30/2018] [Accepted: 02/04/2019] [Indexed: 01/07/2023]
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Cembrowski MS, Spruston N. Heterogeneity within classical cell types is the rule: lessons from hippocampal pyramidal neurons. Nat Rev Neurosci 2019; 20:193-204. [PMID: 30778192 DOI: 10.1038/s41583-019-0125-5] [Citation(s) in RCA: 123] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The mechanistic operation of brain regions is often interpreted by partitioning constituent neurons into 'cell types'. Historically, such cell types were broadly defined by their correspondence to gross features of the nervous system (such as cytoarchitecture). Modern-day neuroscientific techniques, enabling a more nuanced examination of neuronal properties, have illustrated a wealth of heterogeneity within these classical cell types. Here, we review the extent of this within-cell-type heterogeneity in one of the simplest cortical regions of the mammalian brain, the rodent hippocampus. We focus on the mounting evidence that the classical CA3, CA1 and subiculum pyramidal cell types all exhibit prominent and spatially patterned within-cell-type heterogeneity, and suggest these cell types provide a model system for exploring the organization and function of such heterogeneity. Given that the hippocampus is structurally simple and evolutionarily ancient, within-cell-type heterogeneity is likely to be a general and crucial feature of the mammalian brain.
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Affiliation(s)
- Mark S Cembrowski
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
| | - Nelson Spruston
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
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28
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Winnubst J, Bas E, Ferreira TA, Wu Z, Economo MN, Edson P, Arthur BJ, Bruns C, Rokicki K, Schauder D, Olbris DJ, Murphy SD, Ackerman DG, Arshadi C, Baldwin P, Blake R, Elsayed A, Hasan M, Ramirez D, Dos Santos B, Weldon M, Zafar A, Dudman JT, Gerfen CR, Hantman AW, Korff W, Sternson SM, Spruston N, Svoboda K, Chandrashekar J. Reconstruction of 1,000 Projection Neurons Reveals New Cell Types and Organization of Long-Range Connectivity in the Mouse Brain. Cell 2019; 179:268-281.e13. [PMID: 31495573 DOI: 10.1016/j.cell.2019.07.042] [Citation(s) in RCA: 259] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 05/14/2019] [Accepted: 07/23/2019] [Indexed: 01/15/2023]
Abstract
Neuronal cell types are the nodes of neural circuits that determine the flow of information within the brain. Neuronal morphology, especially the shape of the axonal arbor, provides an essential descriptor of cell type and reveals how individual neurons route their output across the brain. Despite the importance of morphology, few projection neurons in the mouse brain have been reconstructed in their entirety. Here we present a robust and efficient platform for imaging and reconstructing complete neuronal morphologies, including axonal arbors that span substantial portions of the brain. We used this platform to reconstruct more than 1,000 projection neurons in the motor cortex, thalamus, subiculum, and hypothalamus. Together, the reconstructed neurons constitute more than 85 meters of axonal length and are available in a searchable online database. Axonal shapes revealed previously unknown subtypes of projection neurons and suggest organizational principles of long-range connectivity.
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Affiliation(s)
- Johan Winnubst
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Erhan Bas
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Tiago A Ferreira
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Zhuhao Wu
- Laboratory of Molecular Genetics, The Rockefeller University, New York, NY 10065, USA
| | - Michael N Economo
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | | | - Ben J Arthur
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Christopher Bruns
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Konrad Rokicki
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - David Schauder
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Donald J Olbris
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Sean D Murphy
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - David G Ackerman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Cameron Arshadi
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Perry Baldwin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Regina Blake
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Ahmad Elsayed
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Mashtura Hasan
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Daniel Ramirez
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Bruno Dos Santos
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Monet Weldon
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Amina Zafar
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Joshua T Dudman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Charles R Gerfen
- Intramural Research Program, National Institute of Mental Health, Bethesda, MD 20892, USA
| | - Adam W Hantman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Wyatt Korff
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Scott M Sternson
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Nelson Spruston
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Karel Svoboda
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
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Matsumoto N, Kitanishi T, Mizuseki K. The subiculum: Unique hippocampal hub and more. Neurosci Res 2019; 143:1-12. [DOI: 10.1016/j.neures.2018.08.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 07/10/2018] [Accepted: 08/03/2018] [Indexed: 01/09/2023]
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Haugland KG, Sugar J, Witter MP. Development and topographical organization of projections from the hippocampus and parahippocampus to the retrosplenial cortex. Eur J Neurosci 2019; 50:1799-1819. [PMID: 30803071 PMCID: PMC6767700 DOI: 10.1111/ejn.14395] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 01/30/2019] [Accepted: 02/15/2019] [Indexed: 12/26/2022]
Abstract
The rat hippocampal formation (HF), parahippocampal region (PHR), and retrosplenial cortex (RSC) play critical roles in spatial processing. These regions are interconnected, and functionally dependent. The neuronal networks mediating this reciprocal dependency are largely unknown. Establishing the developmental timing of network formation will help to understand the emergence of this dependency. We questioned whether the long‐range outputs from HF‐PHR to RSC in Long Evans rats develop during the same time periods as previously reported for the intrinsic HF‐PHR connectivity and the projections from RSC to HF‐PHR. The results of a series of retrograde and anterograde tracing experiments in rats of different postnatal ages show that the postnatal projections from HF‐PHR to RSC display low densities around birth, but develop during the first postnatal week, reaching adult‐like densities around the time of eye‐opening. Developing projections display a topographical organization similar to adult projections. We conclude that the long‐range projections from HF‐PHR to RSC develop in parallel with the intrinsic circuitry of HF‐PHR and the projections of RSC to HF‐PHR.
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Affiliation(s)
- Kamilla G Haugland
- Kavli Institute for Systems Neuroscience, Centre for Neural Computation, Egil and Pauline Braathen and Fred Kavli Center for Cortical Microcircuits, NTNU Norwegian University for Science and Technology, Trondheim, Norway
| | - Jørgen Sugar
- Kavli Institute for Systems Neuroscience, Centre for Neural Computation, Egil and Pauline Braathen and Fred Kavli Center for Cortical Microcircuits, NTNU Norwegian University for Science and Technology, Trondheim, Norway
| | - Menno P Witter
- Kavli Institute for Systems Neuroscience, Centre for Neural Computation, Egil and Pauline Braathen and Fred Kavli Center for Cortical Microcircuits, NTNU Norwegian University for Science and Technology, Trondheim, Norway
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Burst Firing and Spatial Coding in Subicular Principal Cells. J Neurosci 2019; 39:3651-3662. [PMID: 30819796 PMCID: PMC6510334 DOI: 10.1523/jneurosci.1656-18.2019] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 01/27/2019] [Accepted: 02/08/2019] [Indexed: 01/12/2023] Open
Abstract
The subiculum is the major output structure of the hippocampal formation and is involved in learning and memory as well as in spatial navigation. Little is known about how neuronal diversity contributes to function in the subiculum. Previously, in vitro studies have identified distinct bursting patterns in the subiculum. Here, we asked how burst firing is related to spatial coding in vivo. Using juxtacellular recordings in freely moving male rats, we studied the bursting behavior of 102 subicular principal neurons and distinguished two populations: sparsely bursting (∼80%) and dominantly bursting neurons (∼20%). These bursting behaviors were not linked to anatomy: both cell types were found all along the proximodistal and radial axes of the subiculum and all identified cells were pyramidal neurons. However, the distinct burst firing patterns were related to functional differences: the activity of sparsely bursting cells showed a stronger spatial modulation than the activity of dominantly bursting neurons. In addition, all cells classified as boundary cells were sparsely bursting cells. In most sparsely bursting cells, bursts defined sharper firing fields and carried more spatial information than isolated spikes. We conclude that burst firing is functionally relevant to subicular spatially tuned neurons, possibly by serving as a mechanism to transmit spatial information to downstream structures. SIGNIFICANCE STATEMENT The subiculum is the major output structure of the hippocampal formation and is involved in spatial navigation. In vitro, subicular cells can be distinguished by their ability to initiate bursts as brief sequences of spikes fired at high frequencies. Little is known about the relationship between cellular diversity and spatial coding in the subiculum. We performed high-resolution juxtacellular recordings in freely moving rats and found that bursting behavior predicts functional differences between subicular neurons. Specifically, sparsely bursting cells have lower firing rates and carry more spatial information than dominantly bursting cells. Additionally, bursts fired by sparsely bursting cells encoded spatial information better than isolated spikes, indicating that bursts act as a unit of information dedicated to spatial coding.
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Cell-Type-Specific Changes in Intrinsic Excitability in the Subiculum following Learning and Exposure to Novel Environmental Contexts. eNeuro 2019; 5:eN-NWR-0484-18. [PMID: 30627661 PMCID: PMC6325565 DOI: 10.1523/eneuro.0484-18.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 12/29/2022] Open
Abstract
The subiculum is the main target of the hippocampal region CA1 and is the principle output region of the hippocampus. The subiculum is critical to learning and memory, although it has been relatively understudied. There are two functional types of principle neurons within the subiculum: regular spiking (RS) and burst spiking (BS) neurons. To determine whether these cell types are differentially modified by learning-related experience, we performed whole-cell patch clamp recordings from male mouse brain slices following contextual fear conditioning (FC) and memory retrieval relative to a number of control behavioral paradigms. RS cells, but not BS cells, displayed a greater degree of experience-related plasticity in intrinsic excitability measures [afterhyperpolarization (AHP), input resistance (Rinput), current required to elicit a spike], with fear conditioned animals having generally more excitable RS cells compared to naïve controls. Furthermore, we found that the relative proportion of RS to BS neurons is modified by the type of exposure, with the lowest proportion of BS subicular cells occurring in animals that underwent contextual FC followed by a retrieval test. These studies indicate that pyramidal neurons in the subiculum undergo experience- and learning-related plasticity in intrinsic properties in a cell-type-specific manner. As BS and RS cells are thought to convey distinct types of information, this plasticity may be particularly important in encoding, consolidating, and recalling spatial information by modulating information flow from the hippocampus to cortical regions.
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33
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Cembrowski MS, Wang L, Lemire AL, Copeland M, DiLisio SF, Clements J, Spruston N. The subiculum is a patchwork of discrete subregions. eLife 2018; 7:e37701. [PMID: 30375971 PMCID: PMC6226292 DOI: 10.7554/elife.37701] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 10/27/2018] [Indexed: 11/13/2022] Open
Abstract
In the hippocampus, the classical pyramidal cell type of the subiculum acts as a primary output, conveying hippocampal signals to a diverse suite of downstream regions. Accumulating evidence suggests that the subiculum pyramidal cell population may actually be comprised of discrete subclasses. Here, we investigated the extent and organizational principles governing pyramidal cell heterogeneity throughout the mouse subiculum. Using single-cell RNA-seq, we find that the subiculum pyramidal cell population can be deconstructed into eight separable subclasses. These subclasses were mapped onto abutting spatial domains, ultimately producing a complex laminar and columnar organization with heterogeneity across classical dorsal-ventral, proximal-distal, and superficial-deep axes. We further show that these transcriptomically defined subclasses correspond to differential protein products and can be associated with specific projection targets. This work deconstructs the complex landscape of subiculum pyramidal cells into spatially segregated subclasses that may be observed, controlled, and interpreted in future experiments.
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Affiliation(s)
- Mark S Cembrowski
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
| | - Lihua Wang
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
| | - Andrew L Lemire
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
| | - Monique Copeland
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
| | | | - Jody Clements
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
| | - Nelson Spruston
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
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Wozny C, Beed P, Nitzan N, Pössnecker Y, Rost BR, Schmitz D. VGLUT2 Functions as a Differential Marker for Hippocampal Output Neurons. Front Cell Neurosci 2018; 12:337. [PMID: 30333731 PMCID: PMC6176088 DOI: 10.3389/fncel.2018.00337] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 09/12/2018] [Indexed: 01/16/2023] Open
Abstract
The subiculum is the gatekeeper between the hippocampus and cortical areas. Yet, the lack of a pyramidal cell-specific marker gene has made the analysis of the subicular area very difficult. Here we report that the vesicular-glutamate transporter 2 (VGLUT2) functions as a specific marker gene for subicular burst-firing neurons, and demonstrate that VGLUT2-Cre mice allow for Channelrhodopsin-2 (ChR2)-assisted connectivity analysis.
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Affiliation(s)
- Christian Wozny
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
- Neuroscience Research Center, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Prateep Beed
- Neuroscience Research Center, Charité – Universitätsmedizin Berlin, Berlin, Germany
- Berlin Institute of Health, Berlin, Germany
| | - Noam Nitzan
- Neuroscience Research Center, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Yona Pössnecker
- Neuroscience Research Center, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Benjamin R. Rost
- Neuroscience Research Center, Charité – Universitätsmedizin Berlin, Berlin, Germany
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Dietmar Schmitz
- Neuroscience Research Center, Charité – Universitätsmedizin Berlin, Berlin, Germany
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
- NeuroCure – Cluster of Excellence, Charité – Universitätsmedizin Berlin, Berlin, Germany
- Einstein Center for Neurosciences, Berlin, Germany
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Cordella A, Krashia P, Nobili A, Pignataro A, La Barbera L, Viscomi MT, Valzania A, Keller F, Ammassari-Teule M, Mercuri NB, Berretta N, D'Amelio M. Dopamine loss alters the hippocampus-nucleus accumbens synaptic transmission in the Tg2576 mouse model of Alzheimer's disease. Neurobiol Dis 2018; 116:142-154. [DOI: 10.1016/j.nbd.2018.05.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 05/07/2018] [Accepted: 05/15/2018] [Indexed: 12/14/2022] Open
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Abstract
The subiculum is one of the major output areas of the hippocampus and has extensive projections to extrahippocampal targets. It is likely to play a pivotal role in the distribution of outgoing information from the hippocampus. The hippocampus, including the subiculum, is important for the formation, consolidation and retrieval of memory. These functions require a network that is flexible enough to encode incoming information and also allows for reliable distribution, storage and integration into previously encoded memories. Finally, relevant information has to be retrieved in a context-specific manner to allow for an appropriate behavioral response. The subiculum as a gateway between the hippocampus and cortex might serve to integrate and process information from the hippocampus proper and its other inputs before conveying it to more permanent storage locations. This review summarizes how the subiculum is embedded into upstream and downstream circuits, describes what is known about the local network topology and discusses cellular and functional properties of subicular cells subtypes. Lastly, it describes how these properties might help to separate information into parallel output streams and distribute it to its multiple target areas.
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37
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Cellular components and circuitry of the presubiculum and its functional role in the head direction system. Cell Tissue Res 2018; 373:541-556. [PMID: 29789927 DOI: 10.1007/s00441-018-2841-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Accepted: 04/10/2018] [Indexed: 12/20/2022]
Abstract
Orientation in space is a fundamental cognitive process relying on brain-wide neuronal circuits. Many neurons in the presubiculum in the parahippocampal region encode head direction and each head direction cell selectively discharges when the animal faces a specific direction. Here, we attempt to link the current knowledge of afferent and efferent connectivity of the presubiculum to the processing of the head direction signal. We describe the cytoarchitecture of the presubicular six-layered cortex and the morphological and electrophysiological intrinsic properties of principal neurons and interneurons. While the presubicular head direction signal depends on synaptic input from thalamus, the intra- and interlaminar information flow in the microcircuit of the presubiculum may contribute to refine directional tuning. The interaction of a specific interneuron type, the Martinotti cells, with the excitatory pyramidal cells may maintain the head direction signal in the presubiculum with attractor-like properties.
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Cembrowski MS, Phillips MG, DiLisio SF, Shields BC, Winnubst J, Chandrashekar J, Bas E, Spruston N. Dissociable Structural and Functional Hippocampal Outputs via Distinct Subiculum Cell Classes. Cell 2018; 173:1280-1292.e18. [PMID: 29681453 DOI: 10.1016/j.cell.2018.03.031] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 01/22/2018] [Accepted: 03/14/2018] [Indexed: 12/30/2022]
Abstract
The mammalian hippocampus, comprised of serially connected subfields, participates in diverse behavioral and cognitive functions. It has been postulated that parallel circuitry embedded within hippocampal subfields may underlie such functional diversity. We sought to identify, delineate, and manipulate this putatively parallel architecture in the dorsal subiculum, the primary output subfield of the dorsal hippocampus. Population and single-cell RNA-seq revealed that the subiculum can be divided into two spatially adjacent subregions associated with prominent differences in pyramidal cell gene expression. Pyramidal cells occupying these two regions differed in their long-range inputs, local wiring, projection targets, and electrophysiological properties. Leveraging gene-expression differences across these regions, we use genetically restricted neuronal silencing to show that these regions differentially contribute to spatial working memory. This work provides a coherent molecular-, cellular-, circuit-, and behavioral-level demonstration that the hippocampus embeds structurally and functionally dissociable streams within its serial architecture.
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Affiliation(s)
- Mark S Cembrowski
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr., Ashburn, VA 20147, USA.
| | - Matthew G Phillips
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr., Ashburn, VA 20147, USA
| | - Salvatore F DiLisio
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr., Ashburn, VA 20147, USA
| | - Brenda C Shields
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr., Ashburn, VA 20147, USA
| | - Johan Winnubst
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr., Ashburn, VA 20147, USA
| | - Jayaram Chandrashekar
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr., Ashburn, VA 20147, USA
| | - Erhan Bas
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr., Ashburn, VA 20147, USA
| | - Nelson Spruston
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr., Ashburn, VA 20147, USA.
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39
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Turner RW. Sweet T-bursting is the subiculum's true badge. J Physiol 2017; 595:6223. [PMID: 28786112 DOI: 10.1113/jp274981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Ray W Turner
- University of Calgary, Calgary, Alberta, T2N 4N1, Canada
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40
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Joksimovic SM, Eggan P, Izumi Y, Joksimovic SL, Tesic V, Dietz RM, Orfila JE, DiGruccio MR, Herson PS, Jevtovic-Todorovic V, Zorumski CF, Todorovic SM. The role of T-type calcium channels in the subiculum: to burst or not to burst? J Physiol 2017; 595:6327-6348. [PMID: 28744923 PMCID: PMC5621493 DOI: 10.1113/jp274565] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 07/07/2017] [Indexed: 01/16/2023] Open
Abstract
KEY POINTS Pharmacological, molecular and genetic data indicate a prominent role of low-voltage-activated T-type calcium channels (T-channels) in the firing activity of both pyramidal and inhibitory interneurons in the subiculum. Pharmacological inhibition of T-channels switched burst firing with lower depolarizing stimuli to regular spiking, and fully abolished hyperpolarization-induced burst firing. Our molecular studies showed that CaV 3.1 is the most abundantly expressed isoform of T-channels in the rat subiculum. Consistent with this finding, both regular-spiking and burst firing patterns were profoundly depressed in the mouse with global deletion of CaV 3.1 isoform of T-channels. Selective inhibition of T-channels and global deletion of CaV 3.1 channels completely suppressed development of long-term potentiation (LTP) in the CA1-subiculum, but not in the CA3-CA1 pathway. ABSTRACT Several studies suggest that voltage-gated calcium currents are involved in generating high frequency burst firing in the subiculum, but the exact nature of these currents remains unknown. Here, we used selective pharmacology, molecular and genetic approaches to implicate Cav3.1-containing T-channels in subicular burst firing, in contrast to several previous reports discounting T-channels as major contributors to subicular neuron physiology. Furthermore, pharmacological antagonism of T-channels, as well as global deletion of CaV3.1 isoform, completely suppressed development of long-term potentiation (LTP) in the CA1-subiculum, but not in the CA3-CA1 pathway. Our results indicate that excitability and synaptic plasticity of subicular neurons relies heavily on T-channels. Hence, T-channels may be a promising new drug target for different cognitive deficits.
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Affiliation(s)
- Srdjan M Joksimovic
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Pierce Eggan
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Yukitoshi Izumi
- Department of Psychiatry & Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Sonja Lj Joksimovic
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Vesna Tesic
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Robert M Dietz
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - James E Orfila
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Michael R DiGruccio
- Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, CA, 95616, USA
| | - Paco S Herson
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
| | - Charles F Zorumski
- Department of Psychiatry & Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Slobodan M Todorovic
- Department of Anesthesiology, University of Colorado, School of Medicine, Aurora, CO, 80045, USA
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41
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Immunohistochemical investigation of the internal structure of the mouse subiculum. Neuroscience 2016; 337:242-266. [PMID: 27664459 DOI: 10.1016/j.neuroscience.2016.09.027] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 09/13/2016] [Accepted: 09/14/2016] [Indexed: 12/27/2022]
Abstract
The subiculum is the output component of the hippocampal formation and holds a key position in the neural circuitry of memory. Previous studies have demonstrated the subiculum's connectivity to other brain areas in detail; however, little is known regarding its internal structure. We investigated the cytoarchitecture of the temporal and mid-septotemporal parts of the subiculum using immunohistochemistry. The border between the CA1 region and subiculum was determined by both cytoarchitecture and zinc transporter 3 (ZnT3)-immunoreactivity (IR), whereas the border between the subiculum and presubiculum (PreS) was partially indicated by glutamate receptor 1 (GluR1)-IR. The subiculum was divided into proximal and distal subfields based on cytoarchitecture and immunohistochemistry for calbindin (CB), nitric oxide synthase (NOS) and Purkinje cell protein 4 (PCP4). The proximal subiculum (defined here as subiculum 2) was composed of five layers: the molecular layer (layer 1), the medium-sized pyramidal cell layer (layer 2) that contained NOS- and PCP4-positive neurons, the large pyramidal cell layer (layer 3) characterized by the accumulation of ZnT3- (more proximally) and vesicular glutamate transporter 2-positive (more distally) boutons, layer 4 containing polymorphic cells, and the deepest layer 5 composed of PCP4-positive cells with long apical dendrites that reached layer 1. The distal subiculum (subiculum 1) consisting of smaller neurons did not show these features. Quantitative analyses of the size and numerical density of somata substantiated this delineation. Both the proximal-distal division and five-layered structure in the subiculum 2 were confirmed throughout the temporal two-thirds of the subiculum. These findings will provide a new structural basis for hippocampal investigations.
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Korte M, Schmitz D. Cellular and System Biology of Memory: Timing, Molecules, and Beyond. Physiol Rev 2016; 96:647-93. [PMID: 26960344 DOI: 10.1152/physrev.00010.2015] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The storage of information in the mammalian nervous systems is dependent on a delicate balance between change and stability of neuronal networks. The induction and maintenance of processes that lead to changes in synaptic strength to a multistep process which can lead to long-lasting changes, which starts and ends with a highly choreographed and perfectly timed dance of molecules in different cell types of the central nervous system. This is accompanied by synchronization of specific networks, resulting in the generation of characteristic "macroscopic" rhythmic electrical fields, whose characteristic frequencies correspond to certain activity and information-processing states of the brain. Molecular events and macroscopic fields influence each other reciprocally. We review here cellular processes of synaptic plasticity, particularly functional and structural changes, and focus on timing events that are important for the initial memory acquisition, as well as mechanisms of short- and long-term memory storage. Then, we cover the importance of epigenetic events on the long-time range. Furthermore, we consider how brain rhythms at the network level participate in processes of information storage and by what means they participating in it. Finally, we examine memory consolidation at the system level during processes of sleep.
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Affiliation(s)
- Martin Korte
- Zoological Institute, Division of Cellular Neurobiology, Braunschweig, Germany; Helmholtz Centre for Infection Research, AG NIND, Braunschweig, Germany; and Neuroscience Research Centre, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Dietmar Schmitz
- Zoological Institute, Division of Cellular Neurobiology, Braunschweig, Germany; Helmholtz Centre for Infection Research, AG NIND, Braunschweig, Germany; and Neuroscience Research Centre, Charité Universitätsmedizin Berlin, Berlin, Germany
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43
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Xu X, Sun Y, Holmes TC, López AJ. Noncanonical connections between the subiculum and hippocampal CA1. J Comp Neurol 2016; 524:3666-3673. [PMID: 27150503 DOI: 10.1002/cne.24024] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 04/16/2016] [Accepted: 04/18/2016] [Indexed: 12/12/2022]
Abstract
The hippocampal formation is traditionally viewed as having a feedforward, unidirectional circuit organization that promotes propagation of excitatory processes. While the substantial forward projection from hippocampal CA1 to the subiculum has been very well established, accumulating evidence supports the existence of a significant backprojection pathway comprised of both excitatory and inhibitory elements from the subiculum to CA1. Based on these recently updated anatomical connections, such a backprojection could serve to modulate information processing in hippocampal CA1. Here we review the published anatomical and physiological studies on the subiculum to CA1 backprojection, and present recent conclusive anatomical evidence for the presence of noncanonical subicular projections to CA1. New insights into this understudied pathway will improve our understanding of reciprocal CA1-subicular connections and guide future studies on how the subiculum interacts with CA1 to regulate hippocampal circuit activity and learning and memory behaviors. J. Comp. Neurol. 524:3666-3673, 2016. © 2016 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California, USA. .,Department of Biomedical Engineering, University of California, Irvine, California, USA. .,Department of Microbiology and Molecular Genetics, University of California, Irvine, California, USA.
| | - Yanjun Sun
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California, USA
| | - Todd C Holmes
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Alberto J López
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, California, USA
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Graves AR, Moore SJ, Spruston N, Tryba AK, Kaczorowski CC. Brain-derived neurotrophic factor differentially modulates excitability of two classes of hippocampal output neurons. J Neurophysiol 2016; 116:466-71. [PMID: 27146982 PMCID: PMC4978785 DOI: 10.1152/jn.00186.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 05/03/2016] [Indexed: 12/14/2022] Open
Abstract
We show that BDNF mediates acute and long-lasting changes in intrinsic neuronal excitability in two classes of subicular pyramidal neurons (EB and LB neurons). Although BDNF plays similar roles in the induction of synaptic plasticity in these two cell types, it differentially and bidirectionally affects intrinsic excitability and burst plasticity in EB and LB neurons. These cell type-specific effects represent new avenues by which BDNF can influence the well-established information storage function of the hippocampus. Brain-derived neurotrophic factor (BDNF) plays an important role in hippocampus-dependent learning and memory. Canonically, this has been ascribed to an enhancing effect on neuronal excitability and synaptic plasticity in the CA1 region. However, it is the pyramidal neurons in the subiculum that form the primary efferent pathways conveying hippocampal information to other areas of the brain, and yet the effect of BDNF on these neurons has remained unexplored. We present new data that BDNF regulates neuronal excitability and cellular plasticity in a much more complex manner than previously suggested. Subicular pyramidal neurons can be divided into two major classes, which have different electrophysiological and morphological properties, different requirements for the induction of plasticity, and different extrahippocampal projections. We found that BDNF increases excitability in one class of subicular pyramidal neurons yet decreases excitability in the other class. Furthermore, while endogenous BDNF was necessary for the induction of synaptic plasticity in both cell types, BDNF enhanced intrinsic plasticity in one class of pyramidal neurons yet suppressed intrinsic plasticity in the other. Taken together, these data suggest a novel role for BDNF signaling, as it appears to dynamically and bidirectionally regulate the output of hippocampal information to different regions of the brain.
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Affiliation(s)
- A R Graves
- Department of Neurobiology, Northwestern University, Evanston, Illinois; Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, Virginia
| | - S J Moore
- Department of Neurobiology, Northwestern University, Evanston, Illinois; Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, Michigan
| | - N Spruston
- Department of Neurobiology, Northwestern University, Evanston, Illinois; Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, Virginia
| | - A K Tryba
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Pediatrics, The University of Chicago, Chicago, Illinois; and
| | - C C Kaczorowski
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee
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Christiansen K, Dillingham CM, Wright NF, Saunders RC, Vann SD, Aggleton JP. Complementary subicular pathways to the anterior thalamic nuclei and mammillary bodies in the rat and macaque monkey brain. Eur J Neurosci 2016; 43:1044-61. [PMID: 26855336 PMCID: PMC4855639 DOI: 10.1111/ejn.13208] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 01/22/2016] [Accepted: 02/04/2016] [Indexed: 02/01/2023]
Abstract
The origins of the hippocampal (subicular) projections to the anterior thalamic nuclei and mammillary bodies were compared in rats and macaque monkeys using retrograde tracers. These projections form core components of the Papez circuit, which is vital for normal memory. The study revealed a complex pattern of subicular efferents, consistent with the presence of different, parallel information streams, whose segregation appears more marked in the rat brain. In both species, the cells projecting to the mammillary bodies and anterior thalamic nuclei showed laminar separation but also differed along other hippocampal axes. In the rat, these diencephalic inputs showed complementary topographies in the proximal–distal (columnar) plane, consistent with differential involvement in object‐based (proximal subiculum) and context‐based (distal subiculum) information. The medial mammillary inputs, which arose along the anterior–posterior extent of the rat subiculum, favoured the central subiculum (septal hippocampus) and the more proximal subiculum (temporal hippocampus). In contrast, anterior thalamic inputs were largely confined to the dorsal (i.e. septal and intermediate) subiculum, where projections to the anteromedial nucleus favoured the proximal subiculum while those to the anteroventral nucleus predominantly arose in the distal subiculum. In the macaque, the corresponding diencephalic inputs were again distinguished by anterior–posterior topographies, as subicular inputs to the medial mammillary bodies predominantly arose from the posterior hippocampus while subicular inputs to the anteromedial thalamic nucleus predominantly arose from the anterior hippocampus. Unlike the rat, there was no clear evidence of proximal–distal separation as all of these medial diencephalic projections preferentially arose from the more distal subiculum.
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Affiliation(s)
- Kat Christiansen
- School of Psychology, Cardiff University, Tower Building 70, Park Place, Cardiff, CF10 3AT, UK
| | | | - Nicholas F Wright
- School of Psychology, Cardiff University, Tower Building 70, Park Place, Cardiff, CF10 3AT, UK
| | - Richard C Saunders
- Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD, USA
| | - Seralynne D Vann
- School of Psychology, Cardiff University, Tower Building 70, Park Place, Cardiff, CF10 3AT, UK
| | - John P Aggleton
- School of Psychology, Cardiff University, Tower Building 70, Park Place, Cardiff, CF10 3AT, UK
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46
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Abstract
UNLABELLED Cortical and hippocampal oscillations play a crucial role in the encoding, consolidation, and retrieval of memory. Sharp-wave associated ripples have been shown to be necessary for the consolidation of memory. During consolidation, information is transferred from the hippocampus to the neocortex. One of the structures at the interface between hippocampus and neocortex is the subiculum. It is therefore well suited to mediate the transfer and distribution of information from the hippocampus to other areas. By juxtacellular and whole-cell-recordings in awake mice, we show here that in the subiculum a subset of pyramidal cells is activated, whereas another subset is inhibited during ripples. We demonstrate that these functionally different subgroups are predetermined by their cell subtype. Bursting cells are selectively used to transmit information during ripples, whereas the firing probability in regular firing cells is reduced. With multiple patch-clamp recordings in vitro, we show that the cell subtype-specific differences extend into the local network topology. This is reflected in an asymmetric wiring scheme where bursting cells and regular firing cells are recurrently connected among themselves but connections between subtypes exclusively exist from regular to bursting cells. Furthermore, inhibitory connections are more numerous onto regular firing cells than onto bursting cells. We conclude that the network topology contributes to the observed functional diversity of subicular pyramidal cells during sharp-wave associated ripples. SIGNIFICANCE STATEMENT Memory consolidation is dependent on hippocampal activity patterns, so called hippocampal ripples. During these fast oscillations, memory traces are transferred from the hippocampus to the neocortex via the subiculum. We investigated the role of single cells in the subiculum during ripples and found that, dependent on their subtype, they are preferentially activated or inhibited. In addition, these two subtypes, the bursting and regular firing type, are differentially integrated into the local network: inhibitory cells are more densely connected to regular firing cells, and communication between regular and bursting cells is unidirectional. Together with earlier findings on different preferential target regions of these subtypes, we conclude that memory traces are guided to target regions of the activated cell type.
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47
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Sosa M, Gillespie AK, Frank LM. Neural Activity Patterns Underlying Spatial Coding in the Hippocampus. Curr Top Behav Neurosci 2016; 37:43-100. [PMID: 27885550 DOI: 10.1007/7854_2016_462] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The hippocampus is well known as a central site for memory processing-critical for storing and later retrieving the experiences events of daily life so they can be used to shape future behavior. Much of what we know about the physiology underlying hippocampal function comes from spatial navigation studies in rodents, which have allowed great strides in understanding how the hippocampus represents experience at the cellular level. However, it remains a challenge to reconcile our knowledge of spatial encoding in the hippocampus with its demonstrated role in memory-dependent tasks in both humans and other animals. Moreover, our understanding of how networks of neurons coordinate their activity within and across hippocampal subregions to enable the encoding, consolidation, and retrieval of memories is incomplete. In this chapter, we explore how information may be represented at the cellular level and processed via coordinated patterns of activity throughout the subregions of the hippocampal network.
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Affiliation(s)
- Marielena Sosa
- Kavli Institute for Fundamental Neuroscience and Department of Physiology, University of California, San Francisco, USA
| | | | - Loren M Frank
- Kavli Institute for Fundamental Neuroscience and Department of Physiology, University of California, San Francisco, USA. .,Howard Hughes Medical Institute, Maryland, USA.
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48
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Basu J, Siegelbaum SA. The Corticohippocampal Circuit, Synaptic Plasticity, and Memory. Cold Spring Harb Perspect Biol 2015; 7:7/11/a021733. [PMID: 26525152 DOI: 10.1101/cshperspect.a021733] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Synaptic plasticity serves as a cellular substrate for information storage in the central nervous system. The entorhinal cortex (EC) and hippocampus are interconnected brain areas supporting basic cognitive functions important for the formation and retrieval of declarative memories. Here, we discuss how information flow in the EC-hippocampal loop is organized through circuit design. We highlight recently identified corticohippocampal and intrahippocampal connections and how these long-range and local microcircuits contribute to learning. This review also describes various forms of activity-dependent mechanisms that change the strength of corticohippocampal synaptic transmission. A key point to emerge from these studies is that patterned activity and interaction of coincident inputs gives rise to associational plasticity and long-term regulation of information flow. Finally, we offer insights about how learning-related synaptic plasticity within the corticohippocampal circuit during sensory experiences may enable adaptive behaviors for encoding spatial, episodic, social, and contextual memories.
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Affiliation(s)
- Jayeeta Basu
- Department of Neuroscience and Physiology, NYU Neuroscience Institute, New York University School of Medicine, New York, New York 10016
| | - Steven A Siegelbaum
- Kavli Institute for Brain Science, Columbia University, New York, New York 10032 Department of Neuroscience, Columbia University, New York, New York 10032 Department of Pharmacology, Columbia University, New York, New York 10032
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49
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Differential participation of pyramidal cells in generation of spontaneous sharp wave-ripples in the mouse subiculum in vitro. Neurobiol Learn Mem 2015; 125:113-9. [DOI: 10.1016/j.nlm.2015.08.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 08/10/2015] [Accepted: 08/20/2015] [Indexed: 11/20/2022]
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50
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Aggleton JP, Christiansen K. The subiculum: the heart of the extended hippocampal system. PROGRESS IN BRAIN RESEARCH 2015; 219:65-82. [PMID: 26072234 DOI: 10.1016/bs.pbr.2015.03.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
While descriptions of the subiculum often emphasize its role as a recipient of hippocampal inputs, the area also has particular importance as a source of hippocampal projections. The extrinsic projections from the subiculum not only parallel those from hippocampal fields CA1-4 but also terminate in sites that do not receive direct inputs from the rest of the hippocampus. Both electrophysiological and lesion studies reveal how, despite its very dense CA1 inputs, the subiculum has functional properties seemingly independent from the rest of the hippocampus. In understanding the subiculum, it is necessary to appreciate that its connections are topographically organized along all three planes (longitudinal, transverse, and depth). These topographies may enable the subiculum to separate multiple information types and, hence, support multiple functions. The particular significance of the subiculum for learning and memory is underlined by its importance as a source of hippocampal projections to nuclei in the medial diencephalon, which are themselves vital for human memory and rodent spatial learning. Of particular note are its reciprocal connections with the anterior thalamic nuclei, which are not shared by the rest of the hippocampus (CA1-4). These thalamosubiculum connections may be of especial significance for resolving memory problems that suffer high interference and require the flexible use of stimulus representations.
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Affiliation(s)
- John P Aggleton
- School of Psychology, Cardiff University, Cardiff, Wales, UK
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