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Bird AD, Cuntz H, Jedlicka P. Robust and consistent measures of pattern separation based on information theory and demonstrated in the dentate gyrus. PLoS Comput Biol 2024; 20:e1010706. [PMID: 38377108 PMCID: PMC10906873 DOI: 10.1371/journal.pcbi.1010706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 03/01/2024] [Accepted: 12/13/2023] [Indexed: 02/22/2024] Open
Abstract
Pattern separation is a valuable computational function performed by neuronal circuits, such as the dentate gyrus, where dissimilarity between inputs is increased, reducing noise and increasing the storage capacity of downstream networks. Pattern separation is studied from both in vivo experimental and computational perspectives and, a number of different measures (such as orthogonalisation, decorrelation, or spike train distance) have been applied to quantify the process of pattern separation. However, these are known to give conclusions that can differ qualitatively depending on the choice of measure and the parameters used to calculate it. We here demonstrate that arbitrarily increasing sparsity, a noticeable feature of dentate granule cell firing and one that is believed to be key to pattern separation, typically leads to improved classical measures for pattern separation even, inappropriately, up to the point where almost all information about the inputs is lost. Standard measures therefore both cannot differentiate between pattern separation and pattern destruction, and give results that may depend on arbitrary parameter choices. We propose that techniques from information theory, in particular mutual information, transfer entropy, and redundancy, should be applied to penalise the potential for lost information (often due to increased sparsity) that is neglected by existing measures. We compare five commonly-used measures of pattern separation with three novel techniques based on information theory, showing that the latter can be applied in a principled way and provide a robust and reliable measure for comparing the pattern separation performance of different neurons and networks. We demonstrate our new measures on detailed compartmental models of individual dentate granule cells and a dentate microcircuit, and show how structural changes associated with epilepsy affect pattern separation performance. We also demonstrate how our measures of pattern separation can predict pattern completion accuracy. Overall, our measures solve a widely acknowledged problem in assessing the pattern separation of neural circuits such as the dentate gyrus, as well as the cerebellum and mushroom body. Finally we provide a publicly available toolbox allowing for easy analysis of pattern separation in spike train ensembles.
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Affiliation(s)
- Alexander D. Bird
- Computer-Based Modelling in the field of 3R Animal Protection, ICAR3R, Faculty of Medicine, Justus Liebig University, Giessen, Germany
- Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with the Max Planck Society, Frankfurt-am-Main, Germany
- Frankfurt Institute for Advanced Studies, Frankfurt-am-Main, Germany
- Translational Neuroscience Network Giessen, Germany
| | - Hermann Cuntz
- Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with the Max Planck Society, Frankfurt-am-Main, Germany
- Frankfurt Institute for Advanced Studies, Frankfurt-am-Main, Germany
- Translational Neuroscience Network Giessen, Germany
| | - Peter Jedlicka
- Computer-Based Modelling in the field of 3R Animal Protection, ICAR3R, Faculty of Medicine, Justus Liebig University, Giessen, Germany
- Translational Neuroscience Network Giessen, Germany
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2
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Berdugo‐Vega G, Dhingra S, Calegari F. Sharpening the blades of the dentate gyrus: how adult-born neurons differentially modulate diverse aspects of hippocampal learning and memory. EMBO J 2023; 42:e113524. [PMID: 37743770 PMCID: PMC11059975 DOI: 10.15252/embj.2023113524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 06/19/2023] [Accepted: 08/18/2023] [Indexed: 09/26/2023] Open
Abstract
For decades, the mammalian hippocampus has been the focus of cellular, anatomical, behavioral, and computational studies aimed at understanding the fundamental mechanisms underlying cognition. Long recognized as the brain's seat for learning and memory, a wealth of knowledge has been accumulated on how the hippocampus processes sensory input, builds complex associations between objects, events, and space, and stores this information in the form of memories to be retrieved later in life. However, despite major efforts, our understanding of hippocampal cognitive function remains fragmentary, and models trying to explain it are continually revisited. Here, we review the literature across all above-mentioned domains and offer a new perspective by bringing attention to the most distinctive, and generally neglected, feature of the mammalian hippocampal formation, namely, the structural separability of the two blades of the dentate gyrus into "supra-pyramidal" and "infra-pyramidal". Next, we discuss recent reports supporting differential effects of adult neurogenesis in the regulation of mature granule cell activity in these two blades. We propose a model for how differences in connectivity and adult neurogenesis in the two blades can potentially provide a substrate for subtly different cognitive functions.
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Affiliation(s)
- Gabriel Berdugo‐Vega
- CRTD‐Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
- Present address:
Laboratory of Neuroepigenetics, Brain Mind Institute, School of Life Sciences, École Polytechnique Fédérale Lausanne (EPFL)LausanneSwitzerland
| | - Shonali Dhingra
- CRTD‐Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
| | - Federico Calegari
- CRTD‐Center for Regenerative Therapies DresdenTechnische Universität DresdenDresdenGermany
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Lamothe-Molina PJ, Franzelin A, Beck L, Li D, Auksutat L, Fieblinger T, Laprell L, Alhbeck J, Gee CE, Kneussel M, Engel AK, Hilgetag CC, Morellini F, Oertner TG. ΔFosB accumulation in hippocampal granule cells drives cFos pattern separation during spatial learning. Nat Commun 2022; 13:6376. [PMID: 36289226 PMCID: PMC9606265 DOI: 10.1038/s41467-022-33947-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 10/07/2022] [Indexed: 12/25/2022] Open
Abstract
Mice display signs of fear when neurons that express cFos during fear conditioning are artificially reactivated. This finding gave rise to the notion that cFos marks neurons that encode specific memories. Here we show that cFos expression patterns in the mouse dentate gyrus (DG) change dramatically from day to day in a water maze spatial learning paradigm, regardless of training level. Optogenetic inhibition of neurons that expressed cFos on the first training day affected performance days later, suggesting that these neurons continue to be important for spatial memory recall. The mechanism preventing repeated cFos expression in DG granule cells involves accumulation of ΔFosB, a long-lived splice variant of FosB. CA1 neurons, in contrast, repeatedly expressed cFos. Thus, cFos-expressing granule cells may encode new features being added to the internal representation during the last training session. This form of timestamping is thought to be required for the formation of episodic memories.
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Affiliation(s)
- Paul J. Lamothe-Molina
- grid.13648.380000 0001 2180 3484Institute for Synaptic Physiology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Andreas Franzelin
- grid.13648.380000 0001 2180 3484Institute for Synaptic Physiology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Lennart Beck
- grid.13648.380000 0001 2180 3484Institute for Synaptic Physiology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Dong Li
- grid.13648.380000 0001 2180 3484Institute of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Lea Auksutat
- grid.13648.380000 0001 2180 3484Research Group Behavioral Biology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tim Fieblinger
- grid.13648.380000 0001 2180 3484Institute for Synaptic Physiology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Laura Laprell
- grid.13648.380000 0001 2180 3484Institute for Synaptic Physiology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Joachim Alhbeck
- grid.13648.380000 0001 2180 3484Department of Neurophysiology and Pathophysiology, Center for Experimental Medicine (ZEM), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christine E. Gee
- grid.13648.380000 0001 2180 3484Institute for Synaptic Physiology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Matthias Kneussel
- grid.13648.380000 0001 2180 3484Institute for Molecular Neurogenetics, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Andreas K. Engel
- grid.13648.380000 0001 2180 3484Department of Neurophysiology and Pathophysiology, Center for Experimental Medicine (ZEM), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Claus C. Hilgetag
- grid.13648.380000 0001 2180 3484Institute of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Fabio Morellini
- grid.13648.380000 0001 2180 3484Research Group Behavioral Biology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thomas G. Oertner
- grid.13648.380000 0001 2180 3484Institute for Synaptic Physiology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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4
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Guzman SJ, Schlögl A, Espinoza C, Zhang X, Suter BA, Jonas P. How connectivity rules and synaptic properties shape the efficacy of pattern separation in the entorhinal cortex-dentate gyrus-CA3 network. NATURE COMPUTATIONAL SCIENCE 2021; 1:830-842. [PMID: 38217181 DOI: 10.1038/s43588-021-00157-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 10/12/2021] [Indexed: 01/15/2024]
Abstract
Pattern separation is a fundamental brain computation that converts small differences in input patterns into large differences in output patterns. Several synaptic mechanisms of pattern separation have been proposed, including code expansion, inhibition and plasticity; however, which of these mechanisms play a role in the entorhinal cortex (EC)-dentate gyrus (DG)-CA3 circuit, a classical pattern separation circuit, remains unclear. Here we show that a biologically realistic, full-scale EC-DG-CA3 circuit model, including granule cells (GCs) and parvalbumin-positive inhibitory interneurons (PV+-INs) in the DG, is an efficient pattern separator. Both external gamma-modulated inhibition and internal lateral inhibition mediated by PV+-INs substantially contributed to pattern separation. Both local connectivity and fast signaling at GC-PV+-IN synapses were important for maximum effectiveness. Similarly, mossy fiber synapses with conditional detonator properties contributed to pattern separation. By contrast, perforant path synapses with Hebbian synaptic plasticity and direct EC-CA3 connection shifted the network towards pattern completion. Our results demonstrate that the specific properties of cells and synapses optimize higher-order computations in biological networks and might be useful to improve the deep learning capabilities of technical networks.
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Affiliation(s)
- S Jose Guzman
- IST Austria, Klosterneuburg, Austria
- Institute of Molecular Biotechnology, Vienna, Austria
| | | | - Claudia Espinoza
- IST Austria, Klosterneuburg, Austria
- Medical University of Austria, Division of Cognitive Neurobiology, Vienna, Austria
| | - Xiaomin Zhang
- IST Austria, Klosterneuburg, Austria
- Brain Research Institute, University of Zürich, Zurich, Switzerland
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Deficits in Behavioral and Neuronal Pattern Separation in Temporal Lobe Epilepsy. J Neurosci 2021; 41:9669-9686. [PMID: 34620720 PMCID: PMC8612476 DOI: 10.1523/jneurosci.2439-20.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 09/09/2021] [Accepted: 09/21/2021] [Indexed: 11/21/2022] Open
Abstract
In temporal lobe epilepsy, the ability of the dentate gyrus to limit excitatory cortical input to the hippocampus breaks down, leading to seizures. The dentate gyrus is also thought to help discriminate between similar memories by performing pattern separation, but whether epilepsy leads to a breakdown in this neural computation, and thus to mnemonic discrimination impairments, remains unknown. Here we show that temporal lobe epilepsy is characterized by behavioral deficits in mnemonic discrimination tasks, in both humans (females and males) and mice (C57Bl6 males, systemic low-dose kainate model). Using a recently developed assay in brain slices of the same epileptic mice, we reveal a decreased ability of the dentate gyrus to perform certain forms of pattern separation. This is because of a subset of granule cells with abnormal bursting that can develop independently of early EEG abnormalities. Overall, our results linking physiology, computation, and cognition in the same mice advance our understanding of episodic memory mechanisms and their dysfunction in epilepsy.SIGNIFICANCE STATEMENT People with temporal lobe epilepsy (TLE) often have learning and memory impairments, sometimes occurring earlier than the first seizure, but those symptoms and their biological underpinnings are poorly understood. We focused on the dentate gyrus, a brain region that is critical to avoid confusion between similar memories and is anatomically disorganized in TLE. We show that both humans and mice with TLE experience confusion between similar situations. This impairment coincides with a failure of the dentate gyrus to disambiguate similar input signals because of pathologic bursting in a subset of neurons. Our work bridges seizure-oriented and memory-oriented views of the dentate gyrus function, suggests a mechanism for cognitive symptoms in TLE, and supports a long-standing hypothesis of episodic memory theories.
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6
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Hassanpoor H, Saidi M. An investigation into the effective role of astrocyte in the hippocampus pattern separation process: A computational modeling study. J Theor Biol 2020; 487:110114. [PMID: 31836505 DOI: 10.1016/j.jtbi.2019.110114] [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: 07/16/2019] [Revised: 11/15/2019] [Accepted: 12/09/2019] [Indexed: 11/29/2022]
Abstract
A physiologically realistic three layer neuron-astrocyte network model is used to evaluate the biological mechanism in pattern separation. The innovative feature of the model is the use of a combination of three elements: neuron, interneuron and astrocyte. In the input layer, a pyramidal neuron receives input patterns from stimulus current, while in the middle layer there are two pyramidal neurons coupled with two inhibitory interneurons and an astrocyte. Finally, in the third layer, a pyramidal neuron produces the output of the model by integrating the output of two neurons from the middle layer resulting from inhibitory and excitatory connections among neurons, interneurons and the astrocyte. Results of computer simulations show that the neuron-astrocyte network within the hippocampal dentate gyrus can generate diverse, complex and different output patterns to given inputs. It is concluded that astrocytes within the dentate gyrus play an important role in the pattern separation process.
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Affiliation(s)
- Hossein Hassanpoor
- Department of Cognitive Science, Dade Pardazi, Shenakht Mehvar, Atynegar (DSA) Institute, Tehran, Iran.
| | - Maryam Saidi
- Department of Cognitive Science, Dade Pardazi, Shenakht Mehvar, Atynegar (DSA) Institute, Tehran, Iran
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7
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Rahimi S, Ragerdikashani M, Beheshti F, Baghishani F, Hosseini M, Saeedi N, Mirdoosti M, Negah SS. Alteration of the neurogenesis and long term potential of olfactory bulb in an animal model of PTSD. Acta Neurobiol Exp (Wars) 2020. [DOI: 10.21307/ane-2020-030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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8
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Madar AD, Ewell LA, Jones MV. Temporal pattern separation in hippocampal neurons through multiplexed neural codes. PLoS Comput Biol 2019; 15:e1006932. [PMID: 31009459 PMCID: PMC6476466 DOI: 10.1371/journal.pcbi.1006932] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 03/06/2019] [Indexed: 12/18/2022] Open
Abstract
Pattern separation is a central concept in current theories of episodic memory: this computation is thought to support our ability to avoid confusion between similar memories by transforming similar cortical input patterns of neural activity into dissimilar output patterns before their long-term storage in the hippocampus. Because there are many ways one can define patterns of neuronal activity and the similarity between them, pattern separation could in theory be achieved through multiple coding strategies. Using our recently developed assay that evaluates pattern separation in isolated tissue by controlling and recording the input and output spike trains of single hippocampal neurons, we explored neural codes through which pattern separation is performed by systematic testing of different similarity metrics and various time resolutions. We discovered that granule cells, the projection neurons of the dentate gyrus, can exhibit both pattern separation and its opposite computation, pattern convergence, depending on the neural code considered and the statistical structure of the input patterns. Pattern separation is favored when inputs are highly similar, and is achieved through spike time reorganization at short time scales (< 100 ms) as well as through variations in firing rate and burstiness at longer time scales. These multiplexed forms of pattern separation are network phenomena, notably controlled by GABAergic inhibition, that involve many celltypes with input-output transformations that participate in pattern separation to different extents and with complementary neural codes: a rate code for dentate fast-spiking interneurons, a burstiness code for hilar mossy cells and a synchrony code at long time scales for CA3 pyramidal cells. Therefore, the isolated hippocampal circuit itself is capable of performing temporal pattern separation using multiplexed coding strategies that might be essential to optimally disambiguate multimodal mnemonic representations.
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Affiliation(s)
- Antoine D. Madar
- Department of Neuroscience, University of Wisconsin-Madison, WI, United States of America
- Neuroscience Training Program, University of Wisconsin-Madison, WI, United States of America
- Department of Neurobiology, Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, University of Chicago, IL, United States of America
| | - Laura A. Ewell
- Department of Neuroscience, University of Wisconsin-Madison, WI, United States of America
- Institute of Experimental Epileptology and Cognition Research, University of Bonn–Medical Center, Germany
| | - Mathew V. Jones
- Department of Neuroscience, University of Wisconsin-Madison, WI, United States of America
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9
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Madar AD, Ewell LA, Jones MV. Pattern separation of spiketrains in hippocampal neurons. Sci Rep 2019; 9:5282. [PMID: 30918288 PMCID: PMC6437159 DOI: 10.1038/s41598-019-41503-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 03/08/2019] [Indexed: 11/30/2022] Open
Abstract
Pattern separation is a process that minimizes overlap between patterns of neuronal activity representing similar experiences. Theoretical work suggests that the dentate gyrus (DG) performs this role for memory processing but a direct demonstration is lacking. One limitation is the difficulty to measure DG inputs and outputs simultaneously. To rigorously assess pattern separation by DG circuitry, we used mouse brain slices to stimulate DG afferents and simultaneously record DG granule cells (GCs) and interneurons. Output spiketrains of GCs are more dissimilar than their input spiketrains, demonstrating for the first time temporal pattern separation at the level of single neurons in the DG. Pattern separation is larger in GCs than in fast-spiking interneurons and hilar mossy cells, and is amplified in CA3 pyramidal cells. Analysis of the neural noise and computational modelling suggest that this form of pattern separation is not explained by simple randomness and arises from specific presynaptic dynamics. Overall, by reframing the concept of pattern separation in dynamic terms and by connecting it to the physiology of different types of neurons, our study offers a new window of understanding in how hippocampal networks might support episodic memory.
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Affiliation(s)
- Antoine D Madar
- Department of Neuroscience, University of Wisconsin, Madison, WI, 53705, USA. .,Department of Neurobiology, Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, University of Chicago, Chicago, IL, 60637, USA.
| | - Laura A Ewell
- Department of Neuroscience, University of Wisconsin, Madison, WI, 53705, USA.,Institute of Experimental Epileptology and Cognition Research, University of Bonn - Medical Center, Bonn, Germany
| | - Mathew V Jones
- Department of Neuroscience, University of Wisconsin, Madison, WI, 53705, USA
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10
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Espinoza C, Guzman SJ, Zhang X, Jonas P. Parvalbumin + interneurons obey unique connectivity rules and establish a powerful lateral-inhibition microcircuit in dentate gyrus. Nat Commun 2018; 9:4605. [PMID: 30389916 PMCID: PMC6214995 DOI: 10.1038/s41467-018-06899-3] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 10/02/2018] [Indexed: 12/31/2022] Open
Abstract
Parvalbumin-positive (PV+) GABAergic interneurons in hippocampal microcircuits are thought to play a key role in several higher network functions, such as feedforward and feedback inhibition, network oscillations, and pattern separation. Fast lateral inhibition mediated by GABAergic interneurons may implement a winner-takes-all mechanism in the hippocampal input layer. However, it is not clear whether the functional connectivity rules of granule cells (GCs) and interneurons in the dentate gyrus are consistent with such a mechanism. Using simultaneous patch-clamp recordings from up to seven GCs and up to four PV+ interneurons in the dentate gyrus, we find that connectivity is structured in space, synapse-specific, and enriched in specific disynaptic motifs. In contrast to the neocortex, lateral inhibition in the dentate gyrus (in which a GC inhibits neighboring GCs via a PV+ interneuron) is ~ 10-times more abundant than recurrent inhibition (in which a GC inhibits itself). Thus, unique connectivity rules may enable the dentate gyrus to perform specific higher-order computations. GABAergic interneurons are known to provide inhibition to allow computational function of neuronal network. Here, Espinoza and colleagues show that connectivity of granule cells and interneurons in the dentate gyrus of mouse hippocampus are consistent with the circuit architecture capable of performing a winners-take-all mechanism.
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Affiliation(s)
- Claudia Espinoza
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400, Klosterneuburg, Austria
| | - Segundo Jose Guzman
- Institute for Molecular Biotechnology (IMBA), Dr. Bohr-Gasse 3, 1030, Wien, Austria
| | - Xiaomin Zhang
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400, Klosterneuburg, Austria
| | - Peter Jonas
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400, Klosterneuburg, Austria.
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11
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Behavioral assessment of hippocampal function following dietary intervention. FOOD SCIENCE AND HUMAN WELLNESS 2018. [DOI: 10.1016/j.fshw.2018.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Genon S, Reid A, Langner R, Amunts K, Eickhoff SB. How to Characterize the Function of a Brain Region. Trends Cogn Sci 2018; 22:350-364. [PMID: 29501326 PMCID: PMC7978486 DOI: 10.1016/j.tics.2018.01.010] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 01/29/2018] [Accepted: 01/31/2018] [Indexed: 12/12/2022]
Abstract
Many brain regions have been defined, but a comprehensive formalization of each region's function in relation to human behavior is still lacking. Current knowledge comes from various fields, which have diverse conceptions of 'functions'. We briefly review these fields and outline how the heterogeneity of associations could be harnessed to disclose the computational function of any region. Aggregating activation data from neuroimaging studies allows us to characterize the functional engagement of a region across a range of experimental conditions. Furthermore, large-sample data can disclose covariation between brain region features and ecological behavioral phenotyping. Combining these two approaches opens a new perspective to determine the behavioral associations of a brain region, and hence its function and broader role within large-scale functional networks.
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Affiliation(s)
- Sarah Genon
- Institute of Neuroscience and Medicine (INM-1, INM-7), Research Centre Jülich, Jülich, Germany; Institute of Systems Neuroscience, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
| | - Andrew Reid
- School of Psychology, University of Nottingham, Nottingham, UK
| | - Robert Langner
- Institute of Neuroscience and Medicine (INM-1, INM-7), Research Centre Jülich, Jülich, Germany; Institute of Systems Neuroscience, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Katrin Amunts
- Institute of Neuroscience and Medicine (INM-1, INM-7), Research Centre Jülich, Jülich, Germany; C. and O. Vogt Institute for Brain Research, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Simon B Eickhoff
- Institute of Neuroscience and Medicine (INM-1, INM-7), Research Centre Jülich, Jülich, Germany; Institute of Systems Neuroscience, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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13
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Synaptic Plasticity and Excitation-Inhibition Balance in the Dentate Gyrus: Insights from In Vivo Recordings in Neuroligin-1, Neuroligin-2, and Collybistin Knockouts. Neural Plast 2018; 2018:6015753. [PMID: 29670649 PMCID: PMC5835277 DOI: 10.1155/2018/6015753] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 12/02/2017] [Accepted: 12/11/2017] [Indexed: 01/29/2023] Open
Abstract
The hippocampal dentate gyrus plays a role in spatial learning and memory and is thought to encode differences between similar environments. The integrity of excitatory and inhibitory transmission and a fine balance between them is essential for efficient processing of information. Therefore, identification and functional characterization of crucial molecular players at excitatory and inhibitory inputs is critical for understanding the dentate gyrus function. In this minireview, we discuss recent studies unraveling molecular mechanisms of excitatory/inhibitory synaptic transmission, long-term synaptic plasticity, and dentate granule cell excitability in the hippocampus of live animals. We focus on the role of three major postsynaptic proteins localized at excitatory (neuroligin-1) and inhibitory synapses (neuroligin-2 and collybistin). In vivo recordings of field potentials have the advantage of characterizing the effects of the loss of these proteins on the input-output function of granule cells embedded in a network with intact connectivity. The lack of neuroligin-1 leads to deficient synaptic plasticity and reduced excitation but normal granule cell output, suggesting unaltered excitation-inhibition ratio. In contrast, the lack of neuroligin-2 and collybistin reduces inhibition resulting in a shift towards excitation of the dentate circuitry.
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