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Agnes EJ, Vogels TP. Co-dependent excitatory and inhibitory plasticity accounts for quick, stable and long-lasting memories in biological networks. Nat Neurosci 2024; 27:964-974. [PMID: 38509348 PMCID: PMC11089004 DOI: 10.1038/s41593-024-01597-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 02/08/2024] [Indexed: 03/22/2024]
Abstract
The brain's functionality is developed and maintained through synaptic plasticity. As synapses undergo plasticity, they also affect each other. The nature of such 'co-dependency' is difficult to disentangle experimentally, because multiple synapses must be monitored simultaneously. To help understand the experimentally observed phenomena, we introduce a framework that formalizes synaptic co-dependency between different connection types. The resulting model explains how inhibition can gate excitatory plasticity while neighboring excitatory-excitatory interactions determine the strength of long-term potentiation. Furthermore, we show how the interplay between excitatory and inhibitory synapses can account for the quick rise and long-term stability of a variety of synaptic weight profiles, such as orientation tuning and dendritic clustering of co-active synapses. In recurrent neuronal networks, co-dependent plasticity produces rich and stable motor cortex-like dynamics with high input sensitivity. Our results suggest an essential role for the neighborly synaptic interaction during learning, connecting micro-level physiology with network-wide phenomena.
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Affiliation(s)
- Everton J Agnes
- Centre for Neural Circuits and Behaviour, University of Oxford, Oxford, UK.
- Biozentrum, University of Basel, Basel, Switzerland.
| | - Tim P Vogels
- Centre for Neural Circuits and Behaviour, University of Oxford, Oxford, UK
- Institute of Science and Technology Austria, Klosterneuburg, Austria
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2
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Inglebert Y, Wu PY, Tourbina-Kolomiets J, Dang CL, McKinney RA. Synaptopodin is required for long-term depression at Schaffer collateral-CA1 synapses. Mol Brain 2024; 17:17. [PMID: 38566234 PMCID: PMC10988887 DOI: 10.1186/s13041-024-01089-3] [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: 09/28/2023] [Accepted: 03/24/2024] [Indexed: 04/04/2024] Open
Abstract
Synaptopodin (SP), an actin-associated protein found in telencephalic neurons, affects activity-dependant synaptic plasticity and dynamic changes of dendritic spines. While being required for long-term depression (LTD) mediated by metabotropic glutamate receptor (mGluR-LTD), little is known about its role in other forms of LTD induced by low frequency stimulation (LFS-LTD) or spike-timing dependent plasticity (STDP). Using electrophysiology in ex vivo hippocampal slices from SP-deficient mice (SPKO), we show that absence of SP is associated with a deficit of LTD at Sc-CA1 synapses induced by LFS-LTD and STDP. As LTD is known to require AMPA- receptors internalization and IP3-receptors calcium signaling, we tested by western blotting and immunochemistry if there were changes in their expression which we found to be reduced. While we were not able to induce LTD, long-term potentiation (LTP), albeit diminished in SPKO, can be recovered by using a stronger stimulation protocol. In SPKO we found no differences in NMDAR, which are the primary site of calcium signalling to induce LTP. Our study shows, for the first time, the key role of the requirement of SP to allow induction of activity-dependant LTD at Sc-CA1 synapses.
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Affiliation(s)
- Yanis Inglebert
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada.
- Current address Department of Neurosciences, Montreal University, Montreal, Canada.
| | - Pei You Wu
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | | | - Cong Loc Dang
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada.
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3
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Kourosh-Arami M, Komaki A, Gholami M, Marashi SH, Hejazi S. Heterosynaptic plasticity-induced modulation of synapses. J Physiol Sci 2023; 73:33. [PMID: 38057729 DOI: 10.1186/s12576-023-00893-1] [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: 06/17/2023] [Accepted: 11/27/2023] [Indexed: 12/08/2023]
Abstract
Plasticity is a common feature of synapses that is stated in different ways and occurs through several mechanisms. The regular action of the brain needs to be balanced in several neuronal and synaptic features, one of which is synaptic plasticity. The different homeostatic processes, including the balance between excitation/inhibition or homeostasis of synaptic weights at the single-neuron level, may obtain this. Homosynaptic Hebbian-type plasticity causes associative alterations of synapses. Both homosynaptic and heterosynaptic plasticity characterize the corresponding aspects of adjustable synapses, and both are essential for the regular action of neural systems and their plastic synapses.In this review, we will compare homo- and heterosynaptic plasticity and the main factors affecting the direction of plastic changes. This review paper will also discuss the diverse functions of the different kinds of heterosynaptic plasticity and their properties. We argue that a complementary system of heterosynaptic plasticity demonstrates an essential cellular constituent for homeostatic modulation of synaptic weights and neuronal activity.
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Affiliation(s)
- Masoumeh Kourosh-Arami
- Department of Neuroscience, School of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran.
| | - Alireza Komaki
- Department of Neuroscience, School of Science and Advanced Technologies in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Masoumeh Gholami
- Department of Physiology, Medical College, Arak University of Medical Sciences, Arak, Iran
| | | | - Sara Hejazi
- Department of Industrial Engineering & Management Systems, University of Central Florida, Orlando, USA
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4
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Spike timing-dependent plasticity and memory. Curr Opin Neurobiol 2023; 80:102707. [PMID: 36924615 DOI: 10.1016/j.conb.2023.102707] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 01/18/2023] [Accepted: 02/15/2023] [Indexed: 03/16/2023]
Abstract
Spike timing-dependent plasticity (STDP) is a bidirectional form of synaptic plasticity discovered about 30 years ago and based on the relative timing of pre- and post-synaptic spiking activity with a millisecond precision. STDP is thought to be involved in the formation of memory but the millisecond-precision spike-timing required for STDP is difficult to reconcile with the much slower timescales of behavioral learning. This review therefore aims to expose and discuss recent findings about i) the multiple STDP learning rules at both excitatory and inhibitory synapses in vitro, ii) the contribution of STDP-like synaptic plasticity in the formation of memory in vivo and iii) the implementation of STDP rules in artificial neural networks and memristive devices.
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5
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Yuan M, Zhu H, Li Y, Ge F, Lui S, Gong Q, Qiu C, Song H, Zhang W. The DRD2 Taq1A polymorphism moderates the effect of PTSD symptom severity on the left hippocampal CA3 volume: a pilot study. Psychopharmacology (Berl) 2022; 239:3431-3438. [PMID: 34086098 PMCID: PMC9585014 DOI: 10.1007/s00213-021-05882-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 05/21/2021] [Indexed: 02/08/2023]
Abstract
RATIONALE AND OBJECTIVES The hippocampus, especially the CA1, CA3, and dentate gyrus (DG) subfields, is reported to be associated with post-traumatic stress disorder (PTSD) after trauma. However, neuroimaging studies of the associations between PTSD and hippocampal subfield volumes have failed to yield consistent findings. The aim of this study is to examine whether the dopamine D2 receptor (DRD2) Taq1A polymorphism, which is associated with both hippocampal function and PTSD, moderated the association between PTSD severity and hippocampal CA1, CA3 and DG volumes. METHODS T1-weighted images were acquired from 142 trauma survivors from the 2008 Wenchuan earthquake using a 3.0-T magnetic resonance imaging system. Hippocampal subfield segmentations were performed with FreeSurfer v6.0. We used the simple moderation model from the PROCESS v3.4 tool for SPSS 23.0 to examine the association between the rs1800497 polymorphism, PTSD severity, and hippocampal CA3 and DG volumes. RESULTS A significant genotype × PTSD symptom severity interaction was found for the left CA3 volume (ΔF = 5.01, p = 0.008, ΔR2 = 0.05). Post hoc, exploratory analyses deconstructing the interaction revealed that severe PTSD symptomatology were associated with reduced left CA3 volume among TC heterozygotes (t = - 2.86, p = 0.005). CONCLUSIONS This study suggests that DRD2 Taq1A polymorphism moderates the association between PTSD symptomatology and left CA3 volume, which promotes an etiological understanding of the hippocampal atrophy at the subfield level. This highlights the complex effect of environmental stress, and provides possible mechanism for the relationship between the dopaminergic system and hippocampal function in PTSD.
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Affiliation(s)
- Minlan Yuan
- Mental Health Center and Psychiatric Laboratory, the State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, 610041, Chengdu, China
- Huaxi Brain Research Center, West China Hospital of Sichuan University, Chengdu, China
| | - Hongru Zhu
- Mental Health Center and Psychiatric Laboratory, the State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, 610041, Chengdu, China
- Huaxi Brain Research Center, West China Hospital of Sichuan University, Chengdu, China
| | - Yuchen Li
- Mental Health Center and Psychiatric Laboratory, the State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, 610041, Chengdu, China
- Huaxi Brain Research Center, West China Hospital of Sichuan University, Chengdu, China
| | - Fenfen Ge
- Mental Health Center and Psychiatric Laboratory, the State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, 610041, Chengdu, China
- Huaxi Brain Research Center, West China Hospital of Sichuan University, Chengdu, China
| | - Su Lui
- Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
- Radiology Department of the Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qiyong Gong
- Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Changjian Qiu
- Mental Health Center and Psychiatric Laboratory, the State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, 610041, Chengdu, China
- Huaxi Brain Research Center, West China Hospital of Sichuan University, Chengdu, China
| | - Huan Song
- West China Biomedical Big Data Center, West China Hospital, Sichuan University, 610041, Chengdu, China.
- Medical Big Data Center, Sichuan University, Chengdu, 610041, China.
| | - Wei Zhang
- Mental Health Center and Psychiatric Laboratory, the State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, 610041, Chengdu, China.
- Huaxi Brain Research Center, West China Hospital of Sichuan University, Chengdu, China.
- West China Biomedical Big Data Center, West China Hospital, Sichuan University, 610041, Chengdu, China.
- Medical Big Data Center, Sichuan University, Chengdu, 610041, China.
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6
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Albesa-González A, Froc M, Williamson O, Rossum MCWV. Weight dependence in BCM leads to adjustable synaptic competition. J Comput Neurosci 2022; 50:431-444. [PMID: 35764852 PMCID: PMC9666303 DOI: 10.1007/s10827-022-00824-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: 11/23/2021] [Revised: 05/15/2022] [Accepted: 06/08/2022] [Indexed: 11/28/2022]
Abstract
Models of synaptic plasticity have been used to better understand neural development as well as learning and memory. One prominent classic model is the Bienenstock-Cooper-Munro (BCM) model that has been particularly successful in explaining plasticity of the visual cortex. Here, in an effort to include more biophysical detail in the BCM model, we incorporate 1) feedforward inhibition, and 2) the experimental observation that large synapses are relatively harder to potentiate than weak ones, while synaptic depression is proportional to the synaptic strength. These modifications change the outcome of unsupervised plasticity under the BCM model. The amount of feed-forward inhibition adds a parameter to BCM that turns out to determine the strength of competition. In the limit of strong inhibition the learning outcome is identical to standard BCM and the neuron becomes selective to one stimulus only (winner-take-all). For smaller values of inhibition, competition is weaker and the receptive fields are less selective. However, both BCM variants can yield realistic receptive fields.
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Affiliation(s)
- Albert Albesa-González
- School of Psychology and School of Mathematical Sciences, University of Nottingham, Nottingham, NH7 2RD, UK
| | - Maxime Froc
- School of Psychology and School of Mathematical Sciences, University of Nottingham, Nottingham, NH7 2RD, UK
| | - Oliver Williamson
- School of Psychology and School of Mathematical Sciences, University of Nottingham, Nottingham, NH7 2RD, UK
| | - Mark C W van Rossum
- School of Psychology and School of Mathematical Sciences, University of Nottingham, Nottingham, NH7 2RD, UK.
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7
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Frye HE, Izumi Y, Harris AN, Williams SB, Trousdale CR, Sun MY, Sauerbeck AD, Kummer TT, Mennerick S, Zorumski CF, Nelson EC, Dougherty JD, Morón JA. Sex Differences in the Role of CNIH3 on Spatial Memory and Synaptic Plasticity. Biol Psychiatry 2021; 90:766-780. [PMID: 34548146 PMCID: PMC8571071 DOI: 10.1016/j.biopsych.2021.07.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 07/12/2021] [Accepted: 07/12/2021] [Indexed: 01/23/2023]
Abstract
BACKGROUND CNIH3 is an AMPA receptor (AMPAR) auxiliary protein prominently expressed in the dorsal hippocampus (dHPC), a region that plays a critical role in spatial memory and synaptic plasticity. However, the effects of CNIH3 on AMPAR-dependent synaptic function and behavior have not been investigated. METHODS We assessed a gain-of-function model of Cnih3 overexpression in the dHPC and generated and characterized a line of Cnih3-/- C57BL/6 mice. We assessed spatial memory through behavioral assays, protein levels of AMPAR subunits and synaptic proteins by immunoblotting, and long-term potentiation in electrophysiological recordings. We also utilized a super-resolution imaging workflow, SEQUIN (Synaptic Evaluation and Quantification by Imaging of Nanostructure), for analysis of nanoscale synaptic connectivity in the dHPC. RESULTS Overexpression of Cnih3 in the dHPC improved short-term spatial memory in female mice but not in male mice. Cnih3-/- female mice exhibited weakened short-term spatial memory, reduced dHPC synapse density, enhanced expression of calcium-impermeable AMPAR (GluA2-containing) subunits in synaptosomes, and attenuated long-term potentiation maintenance compared with Cnih3+/+ control mice; Cnih3-/- males were unaffected. Further investigation revealed that deficiencies in spatial memory and changes in AMPAR composition and synaptic plasticity were most pronounced during the metestrus phase of the estrous cycle in female Cnih3-/- mice. CONCLUSIONS This study identified a novel effect of sex and estrous on CNIH3's role in spatial memory and synaptic plasticity. Manipulation of CNIH3 unmasked sexually dimorphic effects on spatial memory, synaptic function, AMPAR composition, and hippocampal plasticity. These findings reinforce the importance of considering sex as a biological variable in studies of memory and hippocampal synaptic function.
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Affiliation(s)
- Hannah E Frye
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Pain Center, Washington University School of Medicine, St. Louis, Missouri; Program in Neuroscience, Washington University in St. Louis, St. Louis, Missouri
| | - Yukitoshi Izumi
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri; Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, Missouri
| | - Alexis N Harris
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri
| | - Sidney B Williams
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Pain Center, Washington University School of Medicine, St. Louis, Missouri
| | - Christopher R Trousdale
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Pain Center, Washington University School of Medicine, St. Louis, Missouri
| | - Min-Yu Sun
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri
| | - Andrew D Sauerbeck
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri
| | - Terrance T Kummer
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri
| | - Steven Mennerick
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri; Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, Missouri
| | - Charles F Zorumski
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri; Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, Missouri
| | - Elliot C Nelson
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri
| | - Joseph D Dougherty
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri; Department of Genetics, Washington University School of Medicine, St. Louis, Missouri
| | - Jose A Morón
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Pain Center, Washington University School of Medicine, St. Louis, Missouri; Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri; Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri.
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8
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Inglebert Y, Debanne D. Calcium and Spike Timing-Dependent Plasticity. Front Cell Neurosci 2021; 15:727336. [PMID: 34616278 PMCID: PMC8488271 DOI: 10.3389/fncel.2021.727336] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 08/26/2021] [Indexed: 11/13/2022] Open
Abstract
Since its discovery, spike timing-dependent synaptic plasticity (STDP) has been thought to be a primary mechanism underlying the brain's ability to learn and to form new memories. However, despite the enormous interest in both the experimental and theoretical neuroscience communities in activity-dependent plasticity, it is still unclear whether plasticity rules inferred from in vitro experiments apply to in vivo conditions. Among the multiple reasons why plasticity rules in vivo might differ significantly from in vitro studies is that extracellular calcium concentration use in most studies is higher than concentrations estimated in vivo. STDP, like many forms of long-term synaptic plasticity, strongly depends on intracellular calcium influx for its induction. Here, we discuss the importance of considering physiological levels of extracellular calcium concentration to study functional plasticity.
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Affiliation(s)
- Yanis Inglebert
- UNIS, UMR1072, INSERM, Aix-Marseille University, Marseille, France.,Department of Pharmacology and Therapeutics and Cell Information Systems, McGill University, Montreal, QC, Canada
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9
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Debanne D, Russier M. The contribution of ion channels in input-output plasticity. Neurobiol Learn Mem 2019; 166:107095. [PMID: 31539624 DOI: 10.1016/j.nlm.2019.107095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/04/2019] [Accepted: 09/16/2019] [Indexed: 12/20/2022]
Abstract
Persistent changes that occur in brain circuits are classically thought to be mediated by long-term modifications in synaptic efficacy. Yet, many studies have shown that voltage-gated ion channels located at the input and output side of the neurons are also the subject to persistent modifications. These channels are thus responsible for intrinsic plasticity that is expressed in many different neuronal types including glutamatergic principal neurons and GABAergic interneurons. As for synaptic plasticity, activation of synaptic glutamate receptors initiate persistent modification in neuronal excitability. We review here how synaptic input can be efficiently altered by activity-dependent modulation of ion channels that control EPSP amplification, spike threshold or resting membrane potential. We discuss the nature of the learning rules shared by intrinsic and synaptic plasticity, the mechanisms of ion channel regulation and the impact of intrinsic plasticity on induction of synaptic modifications.
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10
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Sleep Deprivation by Exposure to Novel Objects Increases Synapse Density and Axon-Spine Interface in the Hippocampal CA1 Region of Adolescent Mice. J Neurosci 2019; 39:6613-6625. [PMID: 31263066 DOI: 10.1523/jneurosci.0380-19.2019] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/24/2019] [Accepted: 06/10/2019] [Indexed: 11/21/2022] Open
Abstract
Sleep has been hypothesized to rebalance overall synaptic strength after ongoing learning during waking leads to net synaptic potentiation. If so, because synaptic strength and size are correlated, synapses on average should be larger after wake and smaller after sleep. This prediction was recently confirmed in mouse cerebral cortex using serial block-face electron microscopy (SBEM). However, whether these findings extend to other brain regions is unknown. Moreover, sleep deprivation by gentle handling was reported to produce hippocampal spine loss, raising the question of whether synapse size and number are differentially affected by sleep and waking. Here we applied SBEM to measure axon-spine interface (ASI), the contact area between pre-synapse and post-synapse, and synapse density in CA1 stratum radiatum. Adolescent YFP-H mice were studied after 6-8 h of sleep (S = 6), spontaneous wake at night (W = 4) or wake enforced during the day by novelty exposure (EW = 4; males/females balanced). In each animal ≥425 ASIs were measured and synaptic vesicles were counted in ~100 synapses/mouse. Reconstructed dendrites included many small, nonperforated synapses and fewer large, perforated synapses. Relative to S, ASI sizes in perforated synapses shifted toward higher values after W and more so after EW. ASI sizes in nonperforated synapses grew after EW relative to S and W, and so did their density. ASI size correlated with presynaptic vesicle number but the proportion of readily available vesicles decreased after EW, suggesting presynaptic fatigue. Thus, CA1 synapses undergo changes consistent with sleep-dependent synaptic renormalization and their number increases after extended wake.SIGNIFICANCE STATEMENT Sleep benefits learning, memory consolidation, and the integration of new with old memories, but the underlying mechanisms remain highly debated. One hypothesis suggests that sleep's cognitive benefits stem from its ability to renormalize total synaptic strength, after ongoing learning during wake leads to net synaptic potentiation. Supporting evidence for this hypothesis mainly comes from the cerebral cortex, including the observation that cortical synapses are larger after wake and smaller after sleep. Using serial electron microscopy, we find here that sleep/wake synaptic changes consistent with sleep-dependent synaptic renormalization also occur in the CA1 region. Thus, the role of sleep in maintaining synaptic homeostasis may extend to the hippocampus, a key area for learning and synaptic plasticity.
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11
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From membrane receptors to protein synthesis and actin cytoskeleton: Mechanisms underlying long lasting forms of synaptic plasticity. Semin Cell Dev Biol 2019; 95:120-129. [PMID: 30634048 DOI: 10.1016/j.semcdb.2019.01.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 01/07/2019] [Accepted: 01/08/2019] [Indexed: 12/13/2022]
Abstract
Synaptic plasticity, the activity dependent change in synaptic strength, forms the molecular foundation of learning and memory. Synaptic plasticity includes structural changes, with spines changing their size to accomodate insertion and removal of postynaptic receptors, which are correlated with functional changes. Of particular relevance for memory storage are the long lasting forms of synaptic plasticity which are protein synthesis dependent. Due to the importance of spine structural plasticity and protein synthesis, this review focuses on the signaling pathways that connect synaptic stimulation with regulation of protein synthesis and remodeling of the actin cytoskeleton. We also review computational models that implement novel aspects of molecular signaling in synaptic plasticity, such as the role of neuromodulators and spatial microdomains, as well as highlight the need for computational models that connect activation of memory kinases with spine actin dynamics.
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12
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Higgins I, Stringer S, Schnupp J. A Computational Account of the Role of Cochlear Nucleus and Inferior Colliculus in Stabilizing Auditory Nerve Firing for Auditory Category Learning. Neural Comput 2018; 30:1801-1829. [PMID: 29652586 DOI: 10.1162/neco_a_01085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
It is well known that auditory nerve (AN) fibers overcome bandwidth limitations through the volley principle, a form of multiplexing. What is less well known is that the volley principle introduces a degree of unpredictability into AN neural firing patterns that may be affecting even simple stimulus categorization learning. We use a physiologically grounded, unsupervised spiking neural network model of the auditory brain with spike time dependent plasticity learning to demonstrate that plastic auditory cortex is unable to learn even simple auditory object categories when exposed to the raw AN firing input without subcortical preprocessing. We then demonstrate the importance of nonplastic subcortical preprocessing within the cochlear nucleus and the inferior colliculus for stabilizing and denoising AN responses. Such preprocessing enables the plastic auditory cortex to learn efficient robust representations of the auditory object categories. The biological realism of our model makes it suitable for generating neurophysiologically testable hypotheses.
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Affiliation(s)
- Irina Higgins
- Department of Experimental Psychology, University of Oxford, Oxford, OX2 6GG, U.K.
| | - Simon Stringer
- Department of Experimental Psychology, University of Oxford, Oxford, OX2 6GG, U.K.
| | - Jan Schnupp
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3QX, U.K.
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13
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Higgins I, Stringer S, Schnupp J. Unsupervised learning of temporal features for word categorization in a spiking neural network model of the auditory brain. PLoS One 2017; 12:e0180174. [PMID: 28797034 PMCID: PMC5552261 DOI: 10.1371/journal.pone.0180174] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 06/12/2017] [Indexed: 12/04/2022] Open
Abstract
The nature of the code used in the auditory cortex to represent complex auditory stimuli, such as naturally spoken words, remains a matter of debate. Here we argue that such representations are encoded by stable spatio-temporal patterns of firing within cell assemblies known as polychronous groups, or PGs. We develop a physiologically grounded, unsupervised spiking neural network model of the auditory brain with local, biologically realistic, spike-time dependent plasticity (STDP) learning, and show that the plastic cortical layers of the network develop PGs which convey substantially more information about the speaker independent identity of two naturally spoken word stimuli than does rate encoding that ignores the precise spike timings. We furthermore demonstrate that such informative PGs can only develop if the input spatio-temporal spike patterns to the plastic cortical areas of the model are relatively stable.
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Affiliation(s)
- Irina Higgins
- Department of Experimental Psychology, University of Oxford, Oxford, England
| | - Simon Stringer
- Department of Experimental Psychology, University of Oxford, Oxford, England
| | - Jan Schnupp
- Department of Physiology, Anatomy and Genetics (DPAG), University of Oxford, Oxford, England
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14
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Adrenergic Gate Release for Spike Timing-Dependent Synaptic Potentiation. Neuron 2017; 93:394-408. [PMID: 28103480 DOI: 10.1016/j.neuron.2016.12.039] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 07/08/2016] [Accepted: 12/21/2016] [Indexed: 12/11/2022]
Abstract
Spike timing-dependent synaptic plasticity (STDP) serves as a key cellular correlate of associative learning, which is facilitated by elevated attentional and emotional states involving activation of adrenergic signaling. At cellular levels, adrenergic signaling increases dendrite excitability, but the underlying mechanisms remain elusive. Here we show that activation of β2-adrenoceptors promoted STD long-term synaptic potentiation at mouse hippocampal excitatory synapses by inactivating dendritic Kv1.1-containing potassium channels, which increased dendrite excitability and facilitated dendritic propagation of postsynaptic depolarization, potentially improving coincidental activation of pre- and postsynaptic terminals. We further demonstrate that adrenergic modulation of Kv1.1 was mediated by the signaling scaffold SAP97, which, through direct protein-protein interactions, escorts β2 signaling to remove Kv1.1 from the dendrite surface. These results reveal a mechanism through which the postsynaptic signaling scaffolds bridge the aroused brain state to promote induction of synaptic plasticity and potentially to enhance spike timing and memory encoding.
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Hennequin G, Agnes EJ, Vogels TP. Inhibitory Plasticity: Balance, Control, and Codependence. Annu Rev Neurosci 2017; 40:557-579. [DOI: 10.1146/annurev-neuro-072116-031005] [Citation(s) in RCA: 140] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Guillaume Hennequin
- Computational and Biological Learning Lab, Department of Engineering, University of Cambridge, Cambridge CB2 3EJ, United Kingdom
| | - Everton J. Agnes
- Centre for Neural Circuits and Behaviour, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3SR, United Kingdom
| | - Tim P. Vogels
- Centre for Neural Circuits and Behaviour, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3SR, United Kingdom
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Han R, Wang J, Miao R, Deng B, Qin Y, Yu H, Wei X. Propagation of Collective Temporal Regularity in Noisy Hierarchical Networks. IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS 2017; 28:191-205. [PMID: 28055909 DOI: 10.1109/tnnls.2015.2502993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Neuronal communication between different brain areas is achieved in terms of spikes. Consequently, spike-time regularity is closely related to many cognitive tasks and timing precision of neural information processing. A recent experiment on primate parietal cortex reports that spike-time regularity increases consistently from primary sensory to higher cortical regions. This observation conflicts with the influential view that spikes in the neocortex are fundamentally irregular. To uncover the underlying network mechanism, we construct a multilayered feedforward neural information transmission pathway and investigate how spike-time regularity evolves across subsequent layers. Numerical results reveal that despite the obviously irregular spiking patterns in previous several layers, neurons in downstream layers can generate rather regular spikes, which depends on the network topology. In particular, we find that collective temporal regularity in deeper layers exhibits resonance-like behavior with respect to both synaptic connection probability and synaptic weight, i.e., the optimal topology parameter maximizes the spike-timing regularity. Furthermore, it is demonstrated that synaptic properties, including inhibition, synaptic transient dynamics, and plasticity, have significant impacts on spike-timing regularity propagation. The emergence of the increasingly regular spiking (RS) patterns in higher parietal regions can, thus, be viewed as a natural consequence of spiking activity propagation between different brain areas. Finally, we validate an important function served by increased RS: promoting reliable propagation of spike-rate signals across downstream layers.
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Modulation of the Direction and Magnitude of Hebbian Plasticity in Human Motor Cortex by Stimulus Intensity and Concurrent Inhibition. Brain Stimul 2017; 10:83-90. [DOI: 10.1016/j.brs.2016.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 08/09/2016] [Accepted: 08/10/2016] [Indexed: 11/18/2022] Open
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Xu W, Baker SN. Timing Intervals Using Population Synchrony and Spike Timing Dependent Plasticity. Front Comput Neurosci 2016; 10:123. [PMID: 27990109 PMCID: PMC5133049 DOI: 10.3389/fncom.2016.00123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 11/15/2016] [Indexed: 11/13/2022] Open
Abstract
We present a computational model by which ensembles of regularly spiking neurons can encode different time intervals through synchronous firing. We show that a neuron responding to a large population of convergent inputs has the potential to learn to produce an appropriately-timed output via spike-time dependent plasticity. We explain why temporal variability of this population synchrony increases with increasing time intervals. We also show that the scalar property of timing and its violation at short intervals can be explained by the spike-wise accumulation of jitter in the inter-spike intervals of timing neurons. We explore how the challenge of encoding longer time intervals can be overcome and conclude that this may involve a switch to a different population of neurons with lower firing rate, with the added effect of producing an earlier bias in response. Experimental data on human timing performance show features in agreement with the model's output.
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Affiliation(s)
- Wei Xu
- Movement Laboratory, Institute of Neuroscience, Medical School, Newcastle University Newcastle Upon Tyne, UK
| | - Stuart N Baker
- Movement Laboratory, Institute of Neuroscience, Medical School, Newcastle University Newcastle Upon Tyne, UK
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Valenzuela RA, Micheva KD, Kiraly M, Li D, Madison DV. Array tomography of physiologically-characterized CNS synapses. J Neurosci Methods 2016; 268:43-52. [PMID: 27141856 DOI: 10.1016/j.jneumeth.2016.04.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 04/15/2016] [Accepted: 04/22/2016] [Indexed: 01/11/2023]
Abstract
BACKGROUND The ability to correlate plastic changes in synaptic physiology with changes in synaptic anatomy has been very limited in the central nervous system because of shortcomings in existing methods for recording the activity of specific CNS synapses and then identifying and studying the same individual synapses on an anatomical level. NEW METHOD We introduce here a novel approach that combines two existing methods: paired neuron electrophysiological recording and array tomography, allowing for the detailed molecular and anatomical study of synapses with known physiological properties. RESULTS The complete mapping of a neuronal pair allows determining the exact number of synapses in the pair and their location. We have found that the majority of close appositions between the presynaptic axon and the postsynaptic dendrite in the pair contain synaptic specializations. The average release probability of the synapses between the two neurons in the pair is low, below 0.2, consistent with previous studies of these connections. Other questions, such as receptor distribution within synapses, can be addressed more efficiently by identifying only a subset of synapses using targeted partial reconstructions. In addition, time sensitive events can be captured with fast chemical fixation. COMPARISON WITH EXISTING METHODS Compared to existing methods, the present approach is the only one that can provide detailed molecular and anatomical information of electrophysiologically-characterized individual synapses. CONCLUSIONS This method will allow for addressing specific questions about the properties of identified CNS synapses, even when they are buried within a cloud of millions of other brain circuit elements.
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Affiliation(s)
- Ricardo A Valenzuela
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305-5345, USA
| | - Kristina D Micheva
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305-5345, USA
| | - Marianna Kiraly
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305-5345, USA
| | - Dong Li
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305-5345, USA
| | - Daniel V Madison
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305-5345, USA.
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20
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Fung TK, Law CS, Leung LS. Associative spike timing-dependent potentiation of the basal dendritic excitatory synapses in the hippocampus in vivo. J Neurophysiol 2016; 115:3264-74. [PMID: 27052581 DOI: 10.1152/jn.00188.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 04/05/2016] [Indexed: 12/12/2022] Open
Abstract
Spike timing-dependent plasticity in the hippocampus has rarely been studied in vivo. Using extracellular potential and current source density analysis in urethane-anesthetized adult rats, we studied synaptic plasticity at the basal dendritic excitatory synapse in CA1 after excitation-spike (ES) pairing; E was a weak basal dendritic excitation evoked by stratum oriens stimulation, and S was a population spike evoked by stratum radiatum apical dendritic excitation. We hypothesize that positive ES pairing-generating synaptic excitation before a spike-results in long-term potentiation (LTP) while negative ES pairing results in long-term depression (LTD). Pairing (50 pairs at 5 Hz) at ES intervals of -10 to 0 ms resulted in significant input-specific LTP of the basal dendritic excitatory sink, lasting 60-120 min. Pairing at +10- to +20-ms ES intervals, or unpaired 5-Hz stimulation, did not induce significant basal dendritic or apical dendritic LTP or LTD. No basal dendritic LTD was found after stimulation of stratum oriens with 200 pairs of high-intensity pulses at 25-ms interval. Pairing-induced LTP was abolished by pretreatment with an N-methyl-d-aspartate receptor antagonist, 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), which also reduced spike bursting during 5-Hz pairing. Pairing at 0.5 Hz did not induce spike bursts or basal dendritic LTP. In conclusion, ES pairing at 5 Hz resulted in input-specific basal dendritic LTP at ES intervals of -10 ms to 0 ms but no LTD at ES intervals of -20 to +20 ms. Associative LTP likely occurred because of theta-rhythmic coincidence of subthreshold excitation with a backpropagated spike burst, which are conditions that can occur naturally in the hippocampus.
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Affiliation(s)
- Thomas K Fung
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Clayton S Law
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - L Stan Leung
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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21
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Fourie C, Kiraly M, Madison DV, Montgomery JM. Paired whole cell recordings in organotypic hippocampal slices. J Vis Exp 2014:51958. [PMID: 25285945 DOI: 10.3791/51958] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Pair recordings involve simultaneous whole cell patch clamp recordings from two synaptically connected neurons, enabling not only direct electrophysiological characterization of the synaptic connections between individual neurons, but also pharmacological manipulation of either the presynaptic or the postsynaptic neuron. When carried out in organotypic hippocampal slice cultures, the probability that two neurons are synaptically connected is significantly increased. This preparation readily enables identification of cell types, and the neurons maintain their morphology and properties of synaptic function similar to that in native brain tissue. A major advantage of paired whole cell recordings is the highly precise information it can provide on the properties of synaptic transmission and plasticity that are not possible with other more crude techniques utilizing extracellular axonal stimulation. Paired whole cell recordings are often perceived as too challenging to perform. While there are challenging aspects to this technique, paired recordings can be performed by anyone trained in whole cell patch clamping provided specific hardware and methodological criteria are followed. The probability of attaining synaptically connected paired recordings significantly increases with healthy organotypic slices and stable micromanipulation allowing independent attainment of pre- and postsynaptic whole cell recordings. While CA3-CA3 pyramidal cell pairs are most widely used in the organotypic slice hippocampal preparation, this technique has also been successful in CA3-CA1 pairs and can be adapted to any neurons that are synaptically connected in the same slice preparation. In this manuscript we provide the detailed methodology and requirements for establishing this technique in any laboratory equipped for electrophysiology.
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Affiliation(s)
- Chantelle Fourie
- Department of Physiology and Centre for Brain Research, University of Auckland
| | - Marianna Kiraly
- Department of Molecular and Cellular Physiology, Stanford University
| | - Daniel V Madison
- Department of Molecular and Cellular Physiology, Stanford University
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22
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Khazipov R, Minlebaev M, Valeeva G. Early gamma oscillations. Neuroscience 2013; 250:240-52. [PMID: 23872391 DOI: 10.1016/j.neuroscience.2013.07.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 06/27/2013] [Accepted: 07/09/2013] [Indexed: 10/26/2022]
Abstract
Gamma oscillations have long been considered to emerge late in development. However, recent studies have revealed that gamma oscillations are transiently expressed in the rat barrel cortex during the first postnatal week, a "critical" period of sensory-dependent barrel map formation. The mechanisms underlying the generation and physiological roles of early gamma oscillations (EGOs) in the development of thalamocortical circuits will be discussed in this review. In contrast to adult gamma oscillations, synchronized through gamma-rhythmic perisomatic inhibition, EGOs are primarily driven through feedforward gamma-rhythmic excitatory input from the thalamus. The recruitment of cortical interneurons to EGOs and the emergence of feedforward inhibition are observed by the end of the first postnatal week. EGOs facilitate the precise synchronization of topographically aligned thalamic and cortical neurons. The multiple replay of sensory input during EGOs supports long-term potentiation at thalamocortical synapses. We suggest that this early form of gamma oscillations, which is mechanistically different from adult gamma oscillations, guides barrel map formation during the critical developmental period.
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Affiliation(s)
- R Khazipov
- INMED - INSERM U901, University Aix-Marseille II, Marseille, France; Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.
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23
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Edelmann E, Lessmann V. Dopamine regulates intrinsic excitability thereby gating successful induction of spike timing-dependent plasticity in CA1 of the hippocampus. Front Neurosci 2013; 7:25. [PMID: 23508132 PMCID: PMC3589711 DOI: 10.3389/fnins.2013.00025] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 02/13/2013] [Indexed: 11/13/2022] Open
Abstract
Long-term potentiation (LTP) and long-term depression (LTD) are generally assumed to be cellular correlates for learning and memory. Different types of LTP induction protocols differing in severity of stimulation can be distinguished in CA1 of the hippocampus. To better understand signaling mechanisms and involvement of neuromodulators such as dopamine (DA) in synaptic plasticity, less severe and more physiological low frequency induction protocols should be used. In the study which is reviewed here, critical determinants of spike timing-dependent plasticity (STDP) at hippocampal CA3-CA1 synapses were investigated. We found that DA via D1 receptor signaling, but not adrenergic signaling activated by the β-adrenergic agonist isoproterenol, is important for successful expression of STDP at CA3-CA1 synapses. The DA effect on STDP is paralleled by changes in spike firing properties, thereby changing intrinsic excitability of postsynaptic CA1 neurons, and gating STDP. Whereas β-adrenergic signaling also leads to a similar (but not identical) regulation of firing pattern, it does not enable STDP. In this focused review we will discuss the current literature on dopaminergic modulation of LTP in CA1, with a special focus on timing dependent (t-)LTP, and we will suggest possible reasons for the selective gating of STDP by DA [but not noradrenaline (NA)] in CA1.
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Affiliation(s)
- Elke Edelmann
- Institute of Physiology, Medical School, Otto-von-Guericke University Magdeburg Magdeburg, Germany
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24
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van Rossum MCW, Shippi M, Barrett AB. Soft-bound synaptic plasticity increases storage capacity. PLoS Comput Biol 2012; 8:e1002836. [PMID: 23284281 PMCID: PMC3527223 DOI: 10.1371/journal.pcbi.1002836] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 10/24/2012] [Indexed: 12/02/2022] Open
Abstract
Accurate models of synaptic plasticity are essential to understand the adaptive properties of the nervous system and for realistic models of learning and memory. Experiments have shown that synaptic plasticity depends not only on pre- and post-synaptic activity patterns, but also on the strength of the connection itself. Namely, weaker synapses are more easily strengthened than already strong ones. This so called soft-bound plasticity automatically constrains the synaptic strengths. It is known that this has important consequences for the dynamics of plasticity and the synaptic weight distribution, but its impact on information storage is unknown. In this modeling study we introduce an information theoretic framework to analyse memory storage in an online learning setting. We show that soft-bound plasticity increases a variety of performance criteria by about 18% over hard-bound plasticity, and likely maximizes the storage capacity of synapses. It is generally believed that our memories are stored in the synaptic connections between neurons. Numerous experimental studies have therefore examined when and how the synaptic connections change. In parallel, many computational studies have examined the properties of memory and synaptic plasticity, aiming to better understand human memory and allow for neural network models of the brain. However, the plasticity rules used in most studies are highly simplified and do not take into account the rich behaviour found in experiments. For instance, it has been observed in experiments that it is hard to make strong synapses even stronger. Here we show that this saturation of plasticity enhances the number of memories that can be stored and introduce a general framework to calculate information storage in online learning paradigms.
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Affiliation(s)
- Mark C W van Rossum
- Institute for Adaptive and Neural Computation, School of Informatics, University of Edinburgh, Edinburgh, United Kingdom.
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25
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Ohta H, Sakai S, Ito S, Ishizuka T, Fukazawa Y, Kemuriyama T, Tandai-Hiruma M, Mushiake H, Sato Y, Yawo H, Nishida Y. Paired stimulation between CA3 and CA1 alters excitability of CA3 in the rat hippocampus. Neurosci Lett 2012; 534:182-7. [PMID: 23262087 DOI: 10.1016/j.neulet.2012.11.058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Revised: 11/02/2012] [Accepted: 11/26/2012] [Indexed: 01/09/2023]
Abstract
It is generally accepted that the extent of plasticity is localized to the region around synapses and post-synaptic intracellular signaling cascades. We investigated the presence of long-range retrograde plasticity associated with excitability at pre-synaptic neurons (CA3) and regulated by the firing of post-synaptic neurons (CA1). We used acute hippocampus slices from transgenic rats expressing channelrhodopsin-2 (ChR2) in both CA1 and CA3 neurons. We employed a parallel photostimulation technique, which enabled robust and independent evocation of action potentials in either CA3 or CA1 neurons. Optically evoked CA3 firings were paired either with CA1 simultaneous firings or with CA1 suppression after the prolonged stimulation. Pre-synaptic excitability was monitored by measuring the optically-evoked firing rate (Opt-FR). We found that the Opt-FR of CA3 neurons was long-term up-regulated as a result of synchronous pre- and post-synaptic pairing stimulation, but down-regulated by the pre-synaptic stimulation during post-synaptic suppression. Both pairing-dependent up-regulation and down-regulation were retarded by NMDA receptor blocking or colchicine preincubation. This finding suggest that CA3 excitability is regulated by CA1 neuron activity at the time of CA3 firing.
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Affiliation(s)
- Hiroyuki Ohta
- Department of Physiology, National Defense Medical College, Tokorozawa, Japan.
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26
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Li J, Nie H, Bian W, Dave V, Janak PH, Ye JH. Microinjection of glycine into the ventral tegmental area selectively decreases ethanol consumption. J Pharmacol Exp Ther 2012; 341:196-204. [PMID: 22238211 DOI: 10.1124/jpet.111.190058] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The mechanisms of ethanol addiction are not completely understood. The mesolimbic dopaminergic system is involved in many drug-related behaviors, including ethanol self-administration. The dopaminergic neurons in this system originate in the ventral tegmental area (VTA) and are under the control of GABAergic transmission. Our previous in vitro electrophysiological data indicate that glycine receptors (GlyRs) exist on the GABAergic terminals, which make synapses on VTA dopaminergic neurons, and activation of these GlyRs reduces GABAergic transmission and increases the activity of VTA dopaminergic neurons. In the current study, we tested the hypothesis that the activation of the presynaptic GlyRs in the VTA might interfere with ethanol self-administration. Glycine and strychnine, the selective antagonist of GlyRs, were injected, either alone or in combination, into the VTA of rats. Ethanol self-administration by rats was evaluated by using three different drinking models: intermittent access, continuous access, and operant self-administration. We found that the infusion of glycine into the VTA selectively reduced the intake of ethanol but not sucrose or water in rats chronically exposed to ethanol under the intermittent-access and continuous-access procedures and decreased lever-press responding for ethanol under an operant self-administration procedure. The effects of glycine probably were mediated by strychnine-sensitive GlyRs, because the coinjection of glycine and strychnine reduced neither ethanol intake in the home cages nor lever-press responding for ethanol in the operant chambers. Thus, GlyRs in the VTA may play a critical role in ethanol self-administration in animals chronically exposed to ethanol. Therefore, drugs targeting GlyRs may be beneficial for alcoholics.
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Affiliation(s)
- Jing Li
- Department of Anesthesiology, Pharmacology, and Physiology, UMDNJ, New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA
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27
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Edelmann E, Lessmann V. Dopamine Modulates Spike Timing-Dependent Plasticity and Action Potential Properties in CA1 Pyramidal Neurons of Acute Rat Hippocampal Slices. Front Synaptic Neurosci 2011; 3:6. [PMID: 22065958 PMCID: PMC3207259 DOI: 10.3389/fnsyn.2011.00006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 10/17/2011] [Indexed: 12/25/2022] Open
Abstract
Spike timing-dependent plasticity (STDP) is a cellular model of Hebbian synaptic plasticity which is believed to underlie memory formation. In an attempt to establish a STDP paradigm in CA1 of acute hippocampal slices from juvenile rats (P15–20), we found that changes in excitability resulting from different slice preparation protocols correlate with the success of STDP induction. Slice preparation with sucrose containing ACSF prolonged rise time, reduced frequency adaptation, and decreased latency of action potentials in CA1 pyramidal neurons compared to preparation in conventional ASCF, while other basal electrophysiological parameters remained unaffected. Whereas we observed prominent timing-dependent long-term potentiation (t-LTP) to 171 ± 10% of controls in conventional ACSF, STDP was absent in sucrose prepared slices. This sucrose-induced STDP deficit could not be rescued by stronger STDP paradigms, applying either more pre- and/or postsynaptic stimuli, or by a higher stimulation frequency. Importantly, slice preparation with sucrose containing ACSF did not eliminate theta-burst stimulation induced LTP in CA1 in field potential recordings in our rat hippocampal slices. Application of dopamine (for 10–20 min) to sucrose prepared slices completely rescued t-LTP and recovered action potential properties back to levels observed in ACSF prepared slices. Conversely, acute inhibition of D1 receptor signaling impaired t-LTP in ACSF prepared slices. No similar restoring effect for STDP as seen with dopamine was observed in response to the β-adrenergic agonist isoproterenol. ELISA measurements demonstrated a significant reduction of endogenous dopamine levels (to 61.9 ± 6.9% of ACSF values) in sucrose prepared slices. These results suggest that dopamine signaling is involved in regulating the efficiency to elicit STDP in CA1 pyramidal neurons.
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Affiliation(s)
- Elke Edelmann
- Institute of Physiology, Medical School, Otto-von-Guericke University Magdeburg Magdeburg, Germany
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28
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Kim G, Kandler K. Paired recordings from distant inhibitory neuron pairs by a sequential scanning approach. J Neurosci Methods 2011; 200:185-9. [PMID: 21704076 DOI: 10.1016/j.jneumeth.2011.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 06/09/2011] [Accepted: 06/09/2011] [Indexed: 11/27/2022]
Abstract
Simultaneous recordings from connected neuron pairs have brought important insights into synaptic communication between neurons. However, patch clamp recordings from neuron pairs have been largely restricted to brain areas in which connections among nearby neurons exist at a relatively high probability. In the case of more distant connections or in areas in which neurons are connected with low probability, recordings from synaptically connected neuron pairs have remained scarce. Here, we present a method that allows dual recordings from remotely connected neuron pairs by scanning potential presynaptic neurons. The applicability of this new approach was tested in the inhibitory pathway from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO), a sound localization pathway in the auditory brainstem. Using a three-step approach that sequentially combines focal uncaging of glutamate, pressure application of glutamate, and loose patch recordings allowed us to reliably achieve recordings from distant, synaptically connected GABA/glycinergic MNTB-LSO neuron pairs. Our results demonstrate that single MNTB neurons evoke highly variable mono-synaptic responses in developing LSO neurons, and heterogeneous short term synaptic dynamics, suggesting local variations in the refinement of these inhibitory connections. Paired recordings, enabled by scanning of remotely connected pairs, will be highly useful to perform detailed investigations of the synaptic function and plasticity from these circuits during the period of developmental refinement. In general, this method should provide a valuable tool to find connected neurons in other brain areas in which recording from candidate pairs has a low success rate.
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Affiliation(s)
- Gunsoo Kim
- Department of Neurobiology, University of Pittsburgh School of Medicine, Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA
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29
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Kunkel S, Diesmann M, Morrison A. Limits to the development of feed-forward structures in large recurrent neuronal networks. Front Comput Neurosci 2011; 4:160. [PMID: 21415913 PMCID: PMC3042733 DOI: 10.3389/fncom.2010.00160] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 12/25/2010] [Indexed: 11/25/2022] Open
Abstract
Spike-timing dependent plasticity (STDP) has traditionally been of great interest to theoreticians, as it seems to provide an answer to the question of how the brain can develop functional structure in response to repeated stimuli. However, despite this high level of interest, convincing demonstrations of this capacity in large, initially random networks have not been forthcoming. Such demonstrations as there are typically rely on constraining the problem artificially. Techniques include employing additional pruning mechanisms or STDP rules that enhance symmetry breaking, simulating networks with low connectivity that magnify competition between synapses, or combinations of the above. In this paper, we first review modeling choices that carry particularly high risks of producing non-generalizable results in the context of STDP in recurrent networks. We then develop a theory for the development of feed-forward structure in random networks and conclude that an unstable fixed point in the dynamics prevents the stable propagation of structure in recurrent networks with weight-dependent STDP. We demonstrate that the key predictions of the theory hold in large-scale simulations. The theory provides insight into the reasons why such development does not take place in unconstrained systems and enables us to identify biologically motivated candidate adaptations to the balanced random network model that might enable it.
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Affiliation(s)
- Susanne Kunkel
- Functional Neural Circuits Group, Faculty of Biology, Albert-Ludwig University of Freiburg Germany
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30
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Kim G, Kandler K. Synaptic changes underlying the strengthening of GABA/glycinergic connections in the developing lateral superior olive. Neuroscience 2010; 171:924-33. [PMID: 20888399 DOI: 10.1016/j.neuroscience.2010.09.054] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 09/22/2010] [Accepted: 09/24/2010] [Indexed: 10/19/2022]
Abstract
Before hearing onset, the topographic organization of the auditory GABA/glycinergic pathway from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO) is refined by synaptic silencing and strengthening. The synaptic mechanisms underlying the developmental strengthening of maintained MNTB-LSO connections are unknown. Here we address this question using whole-cell recordings from LSO neurons in slices prepared from prehearing mice. Minimal and maximal stimulation techniques demonstrated that during the first two postnatal weeks, individual LSO neurons lose about 55% of their initial presynaptic MNTB partners while maintained single-fiber connections become about 14-fold stronger. Analysis of MNTB-evoked miniature events indicates that this strengthening is accompanied by a 2-fold increase in quantal amplitude. Strengthening is not caused by an increase in the probability of release because paired pulse ratios (PPRs) increased from 0.7 in newborn animals to 0.9 around hearing onset, indicating a developmental decrease rather than increase in release probability. In addition, a possible soma-dendritic relocation of MNTB input seems unlikely to underlie their strengthening as indicated by analysis of the rise times of synaptic currents. Taken together, we conclude that the developmental strengthening of MNTB-LSO connections is achieved by a 2-fold increase in quantal size and an 8-fold increase in quantal content.
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Affiliation(s)
- G Kim
- Department of Otolaryngology, University of Pittsburgh School of Medicine, Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA
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31
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Graupner M, Brunel N. Mechanisms of induction and maintenance of spike-timing dependent plasticity in biophysical synapse models. Front Comput Neurosci 2010; 4. [PMID: 20948584 PMCID: PMC2953414 DOI: 10.3389/fncom.2010.00136] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 08/25/2010] [Indexed: 01/02/2023] Open
Abstract
We review biophysical models of synaptic plasticity, with a focus on spike-timing dependent plasticity (STDP). The common property of the discussed models is that synaptic changes depend on the dynamics of the intracellular calcium concentration, which itself depends on pre- and postsynaptic activity. We start by discussing simple models in which plasticity changes are based directly on calcium amplitude and dynamics. We then consider models in which dynamic intracellular signaling cascades form the link between the calcium dynamics and the plasticity changes. Both mechanisms of induction of STDP (through the ability of pre/postsynaptic spikes to evoke changes in the state of the synapse) and of maintenance of the evoked changes (through bistability) are discussed.
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Affiliation(s)
- Michael Graupner
- Center for Neural Science, New York University New York City, NY, USA
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32
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Activation conditions for the induction of metabotropic glutamate receptor-dependent long-term depression in hippocampal CA1 pyramidal cells. J Neurosci 2010; 30:1471-5. [PMID: 20107074 DOI: 10.1523/jneurosci.5619-09.2010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Two forms of homosynaptic long-term depression (LTD) are distinguished in hippocampal CA1 pyramidal cells, one which is NMDA receptor dependent and the other metabotropic glutamate receptor (mGluR) dependent. Although the molecular processes involved in mGluR-LTD are well characterized, the conditions of circuit activation required for its induction remain unclear. We show that mGluR-LTD cannot be induced in synaptically coupled CA3-CA1 pyramidal cell pairs. Experiments to address the underlying mechanisms indicate that, even when glutamate transporters are blocked, one presynaptic cell releases insufficient glutamate to evoke an mGluR-mediated current in a connected CA1 cell. These findings imply that extrasynaptic diffusion is not a limiting factor and are consistent with a sparse distribution of functional mGluRs in the dendritic tree of pyramidal cells. Thus, the discharge of multiple Schaffer collaterals to a targeted cell is necessary for mGluR-LTD. Our experiments indicate that approximately eight CA3 inputs to a CA1 pyramidal cell must be activated to induce mGluR-LTD.
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Debanne D, Poo MM. Spike-timing dependent plasticity beyond synapse - pre- and post-synaptic plasticity of intrinsic neuronal excitability. Front Synaptic Neurosci 2010; 2:21. [PMID: 21423507 PMCID: PMC3059692 DOI: 10.3389/fnsyn.2010.00021] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Accepted: 05/30/2010] [Indexed: 01/22/2023] Open
Abstract
Long-lasting plasticity of synaptic transmission is classically thought to be the cellular substrate for information storage in the brain. Recent data indicate however that it is not the whole story and persistent changes in the intrinsic neuronal excitability have been shown to occur in parallel to the induction of long-term synaptic modifications. This form of plasticity depends on the regulation of voltage-gated ion channels. Here we review the experimental evidence for plasticity of neuronal excitability induced at pre- or postsynaptic sites when long-term plasticity of synaptic transmission is induced with Spike-Timing Dependent Plasticity (STDP) protocols. We describe the induction and expression mechanisms of the induced changes in excitability. Finally, the functional synergy between synaptic and non-synaptic plasticity and their spatial extent are discussed.
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Affiliation(s)
- Dominique Debanne
- Institut National de la Santé et de la Recherche Médicale Unité 641 Marseille, France
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Froemke RC, Debanne D, Bi GQ. Temporal modulation of spike-timing-dependent plasticity. Front Synaptic Neurosci 2010; 2:19. [PMID: 21423505 PMCID: PMC3059714 DOI: 10.3389/fnsyn.2010.00019] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 05/27/2010] [Indexed: 11/13/2022] Open
Abstract
Spike-timing-dependent plasticity (STDP) has attracted considerable experimental and theoretical attention over the last decade. In the most basic formulation, STDP provides a fundamental unit – a spike pair – for quantifying the induction of long-term changes in synaptic strength. However, many factors, both pre- and postsynaptic, can affect synaptic transmission and integration, especially when multiple spikes are considered. Here we review the experimental evidence for multiple types of nonlinear temporal interactions in STDP, focusing on the contributions of individual spike pairs, overall spike rate, and precise spike timing for modification of cortical and hippocampal excitatory synapses. We discuss the underlying processes that determine the specific learning rules at different synapses, such as postsynaptic excitability and short-term depression. Finally, we describe the success of efforts toward building predictive, quantitative models of how complex and natural spike trains induce long-term synaptic modifications.
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Affiliation(s)
- Robert C Froemke
- Molecular Neurobiology Program, Departments of Otolaryngology and Physiology/Neuroscience, The Helen and Martin Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine New York, NY, USA
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35
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Buchanan KA, Mellor JR. The activity requirements for spike timing-dependent plasticity in the hippocampus. Front Synaptic Neurosci 2010; 2:11. [PMID: 21423497 PMCID: PMC3059701 DOI: 10.3389/fnsyn.2010.00011] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 05/17/2010] [Indexed: 12/02/2022] Open
Abstract
Synaptic plasticity has historically been investigated most intensely in the hippocampus and therefore it is somewhat surprising that the majority of studies on spike timing-dependent plasticity (STDP) have focused not in the hippocampus but on synapses in the cortex. One of the major reasons for this bias is the relative ease in obtaining paired electrophysiological recordings from synaptically coupled neurons in cortical slices, in comparison to hippocampal slices. Another less obvious reason has been the difficulty in achieving reliable STDP in the hippocampal slice preparation and confusion surrounding the conditions required. The original descriptions of STDP in the hippocampus was performed on paired recordings from neurons in dissociated or slice cultures utilizing single pairs of presynaptic and postsynaptic spikes and were subsequently replicated in acute hippocampal slices. Further work in several laboratories using conditions that more closely replicate the situation in vivo revealed a requirement for multiple postsynaptic spikes that necessarily complicate the absolute timing rules for STDP. Here we review the hippocampal STDP literature focusing on data from acute hippocampal slice preparations and highlighting apparently contradictory results and the variations in experimental conditions that might account for the discrepancies. We conclude by relating the majority of the available experimental data to a model for STDP induction in the hippocampus based on a critical role for postsynaptic Ca2+ dynamics.
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Affiliation(s)
- Katherine A Buchanan
- Department of Neuroscience, Physiology and Pharmacology, University College London London, UK
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36
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Fuenzalida M, Fernández de Sevilla D, Couve A, Buño W. Role of AMPA and NMDA receptors and back-propagating action potentials in spike timing-dependent plasticity. J Neurophysiol 2009; 103:47-54. [PMID: 19864442 DOI: 10.1152/jn.00416.2009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The cellular mechanisms that mediate spike timing-dependent plasticity (STDP) are largely unknown. We studied in vitro in CA1 pyramidal neurons the contribution of AMPA and N-methyl-d-aspartate (NMDA) components of Schaffer collateral (SC) excitatory postsynaptic potentials (EPSPs; EPSP(AMPA) and EPSP(NMDA)) and of the back-propagating action potential (BAP) to the long-term potentiation (LTP) induced by a STDP protocol that consisted in pairing an EPSP and a BAP. Transient blockade of EPSP(AMPA) with 7-nitro-2,3-dioxo-1,4-dihydroquinoxaline-6-carbonitrile (CNQX) during the STDP protocol prevented LTP. Contrastingly LTP was induced under transient inhibition of EPSP(AMPA) by combining SC stimulation, an imposed EPSP(AMPA)-like depolarization, and BAP or by coupling the EPSP(NMDA) evoked under sustained depolarization (approximately -40 mV) and BAP. In Mg(2+)-free solution EPSP(NMDA) and BAP also produced LTP. Suppression of EPSP(NMDA) or BAP always prevented LTP. Thus activation of NMDA receptors and BAPs are needed but not sufficient because AMPA receptor activation is also obligatory for STDP. However, a transient depolarization of another origin that unblocks NMDA receptors and a BAP may also trigger LTP.
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Affiliation(s)
- Marco Fuenzalida
- Instituto Cajal, Consejo Superior de Investigaciones Cientificas, Avenida Dr. Arce 37, Madrid, Spain
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37
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Intact long-term potentiation but reduced connectivity between neocortical layer 5 pyramidal neurons in a mouse model of Rett syndrome. J Neurosci 2009; 29:11263-70. [PMID: 19741133 DOI: 10.1523/jneurosci.1019-09.2009] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mutations in MECP2 cause Rett syndrome and some related forms of mental retardation and autism. Mecp2-null mice exhibit symptoms reminiscent of Rett syndrome including deficits in learning. Previous reports demonstrated impaired long-term potentiation (LTP) in slices of symptomatic Mecp2-null mice, and decreased excitatory neurotransmission, but the causal relationship between these phenomena is unclear. Reduced plasticity could lead to altered transmission, or reduced excitatory transmission could alter the ability to induce LTP. To help distinguish these possibilities, we compared LTP induction and baseline synaptic transmission at synapses between layer 5 cortical pyramidal neurons in slices of wild-type and Mecp2-null mice. Paired recordings reveal that LTP induction mechanisms are intact in Mecp2-null connections, even after the onset of symptoms. However, fewer connections were found in Mecp2-null mice and individual connections were weaker. These data suggest that loss of MeCP2 function reduces excitatory synaptic connectivity and that this precedes deficits in plasticity.
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38
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Billings G, van Rossum MCW. Memory retention and spike-timing-dependent plasticity. J Neurophysiol 2009; 101:2775-88. [PMID: 19297513 DOI: 10.1152/jn.91007.2008] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Memory systems should be plastic to allow for learning; however, they should also retain earlier memories. Here we explore how synaptic weights and memories are retained in models of single neurons and networks equipped with spike-timing-dependent plasticity. We show that for single neuron models, the precise learning rule has a strong effect on the memory retention time. In particular, a soft-bound, weight-dependent learning rule has a very short retention time as compared with a learning rule that is independent of the synaptic weights. Next, we explore how the retention time is reflected in receptive field stability in networks. As in the single neuron case, the weight-dependent learning rule yields less stable receptive fields than a weight-independent rule. However, receptive fields stabilize in the presence of sufficient lateral inhibition, demonstrating that plasticity in networks can be regulated by inhibition and suggesting a novel role for inhibition in neural circuits.
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Affiliation(s)
- Guy Billings
- Neuroinformatics Doctoral Training Centre, University of Edinburgh, Edinburgh, United Kingdom.
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39
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Paired-recordings from synaptically coupled cortical and hippocampal neurons in acute and cultured brain slices. Nat Protoc 2008; 3:1559-68. [PMID: 18802437 DOI: 10.1038/nprot.2008.147] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Analysis of synaptic transmission, synaptic plasticity, axonal processing, synaptic timing or electrical coupling requires the simultaneous recording of both the pre- and postsynaptic compartments. Paired-recording technique of monosynaptically connected neurons is also an appropriate technique to probe the function of small molecules (calcium buffers, peptides or small proteins) at presynaptic terminals that are too small to allow direct whole-cell patch-clamp recording. We describe here a protocol for obtaining, in acute and cultured slices, synaptically connected pairs of cortical and hippocampal neurons, with a reasonably high probability. The protocol includes four main stages (acute/cultured slice preparation, visualization, recording and analysis) and can be completed in approximately 4 h.
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40
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Sjöström PJ, Rancz EA, Roth A, Häusser M. Dendritic excitability and synaptic plasticity. Physiol Rev 2008; 88:769-840. [PMID: 18391179 DOI: 10.1152/physrev.00016.2007] [Citation(s) in RCA: 418] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Most synaptic inputs are made onto the dendritic tree. Recent work has shown that dendrites play an active role in transforming synaptic input into neuronal output and in defining the relationships between active synapses. In this review, we discuss how these dendritic properties influence the rules governing the induction of synaptic plasticity. We argue that the location of synapses in the dendritic tree, and the type of dendritic excitability associated with each synapse, play decisive roles in determining the plastic properties of that synapse. Furthermore, since the electrical properties of the dendritic tree are not static, but can be altered by neuromodulators and by synaptic activity itself, we discuss how learning rules may be dynamically shaped by tuning dendritic function. We conclude by describing how this reciprocal relationship between plasticity of dendritic excitability and synaptic plasticity has changed our view of information processing and memory storage in neuronal networks.
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Affiliation(s)
- P Jesper Sjöström
- Wolfson Institute for Biomedical Research and Department of Physiology, University College London, London, United Kingdom
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41
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Finelli LA, Haney S, Bazhenov M, Stopfer M, Sejnowski TJ. Synaptic learning rules and sparse coding in a model sensory system. PLoS Comput Biol 2008; 4:e1000062. [PMID: 18421373 PMCID: PMC2278376 DOI: 10.1371/journal.pcbi.1000062] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Accepted: 03/18/2008] [Indexed: 11/18/2022] Open
Abstract
Neural circuits exploit numerous strategies for encoding information. Although the functional significance of individual coding mechanisms has been investigated, ways in which multiple mechanisms interact and integrate are not well understood. The locust olfactory system, in which dense, transiently synchronized spike trains across ensembles of antenna lobe (AL) neurons are transformed into a sparse representation in the mushroom body (MB; a region associated with memory), provides a well-studied preparation for investigating the interaction of multiple coding mechanisms. Recordings made in vivo from the insect MB demonstrated highly specific responses to odors in Kenyon cells (KCs). Typically, only a few KCs from the recorded population of neurons responded reliably when a specific odor was presented. Different odors induced responses in different KCs. Here, we explored with a biologically plausible model the possibility that a form of plasticity may control and tune synaptic weights of inputs to the mushroom body to ensure the specificity of KCs' responses to familiar or meaningful odors. We found that plasticity at the synapses between the AL and the MB efficiently regulated the delicate tuning necessary to selectively filter the intense AL oscillatory output and condense it to a sparse representation in the MB. Activity-dependent plasticity drove the observed specificity, reliability, and expected persistence of odor representations, suggesting a role for plasticity in information processing and making a testable prediction about synaptic plasticity at AL-MB synapses. The way in which the brain encodes, processes, transforms, and stores sensory information is a fundamental question in systems neuroscience. One challenge is to understand how neural oscillations, synchrony, population coding, and sparseness interact in the process of transforming and transferring information. Another question is how synaptic plasticity, the ability of synapses to change their strength, interacts efficiently with these different coding strategies to support learning and information storage. We approached these questions, rarely accessible to direct experimental investigation, in the olfactory system of the locust, a well-studied example. Here, the neurons in the antennal lobe carry neural representations of odor identity using dense, spatially distributed, oscillatory synchronized patterns of neural activity. Odor information cannot be interpreted by considering their activity independently. On the contrary, in the mushroom body—the next processing region, involved in the storage and retrieval of olfactory memories and analogous to the olfactory cortex—odor representations are sparse and carried by more selective neurons. Sparse information coding by ensembles of neurons provides several important advantages including high memory capacity, low overlap between stored objects, and easy information retrieval. How is this sparseness achieved? Here, with a rigorous computational model of the olfactory system, we demonstrate that plasticity at the input afferents to the mushroom body can efficiently mediate the delicate tuning necessary to selectively filter intense sensory input, condensing it to the sparse responses observed in the mushroom body. Our results suggest a general mechanism for plasticity-enabled sparse representations in other sensory systems, such as the visual system. Overall, we illustrate a potential central role for plasticity in the transfer of information across different coding strategies within neural systems.
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Affiliation(s)
- Luca A Finelli
- Computational Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America.
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42
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Campanac E, Debanne D. Spike timing-dependent plasticity: a learning rule for dendritic integration in rat CA1 pyramidal neurons. J Physiol 2007; 586:779-93. [PMID: 18048448 DOI: 10.1113/jphysiol.2007.147017] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Long-term plasticity of dendritic integration is induced in parallel with long-term potentiation (LTP) or depression (LTD) based on presynaptic activity patterns. It is, however, not clear whether synaptic plasticity induced by temporal pairing of pre- and postsynaptic activity is also associated with synergistic modification in dendritic integration. We show here that the spike timing-dependent plasticity (STDP) rule accounts for long-term changes in dendritic integration in CA1 pyramidal neurons in vitro. Positively correlated pre- and postsynaptic activity (delay: +5/+50 ms) induced LTP and facilitated dendritic integration. Negatively correlated activity (delay: -5/-50 ms) induced LTD and depressed dendritic integration. These changes were not observed following positive or negative pairing with long delays (> +/-50 ms) or when NMDA receptors were blocked. The amplitude-slope relation of the EPSP was facilitated after LTP and depressed after LTD. These effects could be mimicked by voltage-gated channel blockers, suggesting that the induced changes in EPSP waveform involve the regulation of voltage-gated channel activity. Importantly, amplitude-slope changes induced by STDP were found to be input specific, indicating that the underlying changes in excitability are restricted to a limited portion of the dendrites. We conclude that STDP is a common learning rule for long-term plasticity of both synaptic transmission and dendritic integration, thus constituting a form of functional redundancy that insures significant changes in the neuronal output when synaptic plasticity is induced.
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Affiliation(s)
- Emilie Campanac
- INSERM U641, Faculté de médecine secteur nord, IFR 11, Marseille, F-13916, France
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43
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Abstract
This protocol describes a method for making and culturing rat hippocampal organotypic slices on membrane inserts. Supplementary videos are included to demonstrate visually the different steps of the procedure. Cultured hippocampal slices has been increasingly used as a model for synaptic studies of the brain as they allow examination of mid to long term manipulations in a preparation where the gross cytoarchitecture of the hippocampus is preserved. Combining techniques such as molecular biology, electrophysiology and immunohistochemistry to study physiological or pathological processes can easily be applied to organotypic slices. The technique described here can be used to make organotypic slices from other parts of the brain, other rodent species and from a range of ages. This protocol can be completed in 3 h.
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Affiliation(s)
- Anna De Simoni
- Department of Physiology, University College London, Gower Street, London WCIE 6BT, UK.
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44
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Standage D, Jalil S, Trappenberg T. Computational consequences of experimentally derived spike-time and weight dependent plasticity rules. BIOLOGICAL CYBERNETICS 2007; 96:615-23. [PMID: 17468882 DOI: 10.1007/s00422-007-0152-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Accepted: 03/15/2007] [Indexed: 05/15/2023]
Abstract
We present two weight- and spike-time dependent synaptic plasticity rules consistent with the physiological data of Bi and Poo (J Neurosci 18:10464-10472, 1998). One rule assumes synaptic saturation, while the other is scale free. We extend previous analyses of the asymptotic consequences of weight-dependent STDP to the case of strongly correlated pre- and post-synaptic spiking, more closely resembling associative learning. We further provide a general formula for the contribution of any number of spikes to synaptic drift. Asymptotic weights are shown to principally depend on the correlation and rate of pre- and post-synaptic activity, decreasing with increasing rate under correlated activity, and increasing with rate under uncorrelated activity. Spike train statistics reveal a quantitative effect only in the pre-asymptotic regime, and we provide a new interpretation of the relation between BCM and STDP data.
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Affiliation(s)
- Dominic Standage
- Faculty of Computer Science, Dalhousie University, 6050 University Avenue, Halifax, NS, Canada B3H 1W5
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45
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Chen LY, Rex CS, Casale MS, Gall CM, Lynch G. Changes in synaptic morphology accompany actin signaling during LTP. J Neurosci 2007; 27:5363-72. [PMID: 17507558 PMCID: PMC6672340 DOI: 10.1523/jneurosci.0164-07.2007] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Stabilization of long-term potentiation (LTP) is commonly proposed to involve changes in synaptic morphology and reorganization of the spine cytoskeleton. Here we tested whether, as predicted from this hypothesis, induction of LTP by theta-burst stimulation activates an actin regulatory pathway and alters synapse morphology within the same dendritic spines. TBS increased severalfold the numbers of spines containing phosphorylated (p) p21-activated kinase (PAK) or its downstream target cofilin; the latter regulates actin filament assembly. The PAK/cofilin phosphoproteins were increased at 2 min but not 30 s post-TBS, peaked at 7 min, and then declined. Double immunostaining for the postsynaptic density protein PSD95 revealed that spines with high pPAK or pCofilin levels had larger synapses (+60-70%) with a more normal size frequency distribution than did neighboring spines. Based on these results and simulations of shape changes to synapse-like objects, we propose that theta stimulation markedly increases the probability that a spine will enter a state characterized by a large, ovoid synapse and that this morphology is important for expression and later stabilization of LTP.
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Affiliation(s)
| | - Christopher S. Rex
- Department of Neurobiology and Behavior, University of California, Irvine, California 92697-4550
| | - Malcolm S. Casale
- Psychiatry and Human Behavior, University of California, Irvine, California 92697-4292, and
| | - Christine M. Gall
- Departments of Anatomy and Neurobiology and
- Department of Neurobiology and Behavior, University of California, Irvine, California 92697-4550
| | - Gary Lynch
- Psychiatry and Human Behavior, University of California, Irvine, California 92697-4292, and
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46
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Parker D, Gilbey T. Developmental differences in neuromodulation and synaptic properties in the lamprey spinal cord. Neuroscience 2007; 145:142-52. [PMID: 17207575 DOI: 10.1016/j.neuroscience.2006.11.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 10/30/2006] [Accepted: 11/27/2006] [Indexed: 11/21/2022]
Abstract
Functional properties in the spinal cord change during development to adapt motor outputs to differing behavioral requirements. Here, we have examined whether there are also developmental differences in spinal cord plasticity by comparing the neuromodulatory effects of substance P in the larval lamprey spinal cord with its previously characterized effects in premigratory adults. The premigratory adult effects of substance P were all significantly reduced in larvae. As the adult effects of substance P depend on the N-methyl-d-aspartate (NMDA)-dependent potentiation of glutamatergic synaptic transmission, we examined if the developmental differences in neuromodulation were associated with differences in synaptic properties. We found that the amplitude, rise time, and half-width of excitatory postsynaptic potentials (EPSPs) from excitatory network interneurons were all significantly reduced in larvae compared with adults. These differences were associated with a reduction in the NMDA component of larval EPSPs, an effect that could have contributed to the reduced modulatory effects of substance P in larvae. In contrast to glutamatergic inputs, the amplitude, rise time, and half-width of inhibitory postsynaptic potentials (IPSPs) from ipsilateral inhibitory interneurons were all significantly increased in larvae compared with adults. Substance P also potentiated larval IPSP amplitudes, an effect not seen in adults. This increase in inhibition contributed to the reduced effects of substance P in larvae, as premigratory adult-like modulation could be evoked when inhibition was blocked with strychnine. These results suggest that opposite developmental changes in excitatory and inhibitory synaptic transmission and their modulation are associated with developmental differences in spinal cord neuromodulation.
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Affiliation(s)
- D Parker
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
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47
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Sjöström PJ, Häusser M. A cooperative switch determines the sign of synaptic plasticity in distal dendrites of neocortical pyramidal neurons. Neuron 2006; 51:227-38. [PMID: 16846857 DOI: 10.1016/j.neuron.2006.06.017] [Citation(s) in RCA: 282] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 05/02/2006] [Accepted: 06/19/2006] [Indexed: 11/19/2022]
Abstract
Pyramidal neurons in the cerebral cortex span multiple cortical layers. How the excitable properties of pyramidal neuron dendrites allow these neurons to both integrate activity and store associations between different layers is not well understood, but is thought to rely in part on dendritic backpropagation of action potentials. Here we demonstrate that the sign of synaptic plasticity in neocortical pyramidal neurons is regulated by the spread of the backpropagating action potential to the synapse. This creates a progressive gradient between LTP and LTD as the distance of the synaptic contacts from the soma increases. At distal synapses, cooperative synaptic input or dendritic depolarization can switch plasticity between LTD and LTP by boosting backpropagation of action potentials. This activity-dependent switch provides a mechanism for associative learning across different neocortical layers that process distinct types of information.
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Affiliation(s)
- Per Jesper Sjöström
- Wolfson Institute for Biomedical Research, Department of Physiology, University College London, London WC1E 6BT, United Kingdom.
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48
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Abstract
Information in the nervous system may be carried by both the rate and timing of neuronal spikes. Recent findings of spike timing-dependent plasticity (STDP) have fueled the interest in the potential roles of spike timing in processing and storage of information in neural circuits. Induction of long-term potentiation (LTP) and long-term depression (LTD) in a variety of in vitro and in vivo systems has been shown to depend on the temporal order of pre- and postsynaptic spiking. Spike timing-dependent modification of neuronal excitability and dendritic integration was also observed. Such STDP at the synaptic and cellular level is likely to play important roles in activity-induced functional changes in neuronal receptive fields and human perception.
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Affiliation(s)
- Yang Dan
- Division of Neurobiology, Department of Molecular and Cell Biology, and Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, USA.
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49
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Abstract
The magnitude and direction of synaptic plasticity can be determined by the precise timing of presynaptic and postsynaptic action potentials on a millisecond timescale. In vivo, however, neural activity has structure on longer timescales. Here we show that plasticity at the CA3-CA1 synapse depends strongly on parameters other than millisecond spike timing. As a result, the notion that a single spike-timing-dependent plasticity (STDP) rule alone can fully describe the mapping between neural activity and synapse strength is invalid. We have begun to explore the influence of additional behaviorally relevant activity parameters on STDP and found conditions under which underlying spike-timing-dependent rules for potentiation and depression can be separated from one another. Potentiation requires postsynaptic burst firing at 5 Hz or higher, a firing pattern that occurs during the theta rhythm. Potentiation is measurable after only tens of presynaptic-before-postsynaptic pairings. Depression requires hundreds of pairings but has less stringent long timescale requirements and broad timing dependence. By varying these parameters, we obtain STDP curves that are long-term potentiation only, bidirectional, or long-term depression only. This expanded description of the CA3-CA1 learning rule reconciles apparent contradictions between spike-timing-dependent plasticity and previous work at CA3-CA1 synapses.
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50
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Debanne D, Thompson SM, Gähwiler BH. A brief period of epileptiform activity strengthens excitatory synapses in the rat hippocampus in vitro. Epilepsia 2006; 47:247-56. [PMID: 16499748 DOI: 10.1111/j.1528-1167.2006.00416.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE We examined here whether a very short period of epileptiform activity could produce lasting modifications of synaptic strength and network properties in the rat hippocampus in vitro. METHODS Synaptic transmission at CA3-CA1 and at CA3-CA3 pyramidal cell synapses was monitored in hippocampal slice cultures before and after a very brief episode of epileptiform activity (20-180 s) induced with bicuculline methochloride. RESULTS We show here that a brief period of epileptiform activity induces long-lasting potentiation of glutamatergic transmission at CA3-CA1 and at CA3-CA3 pyramidal cell synapses. This potentiation also was observed at synapses formed by pairs of monosynaptically connected neurons. It was dependent on N-methyl-d-aspartate (NMDA) receptors, occluded classic long-term potentiation, and could be depotentiated by low-frequency stimulation at 3 Hz. Recruitment of polysynaptic pathways within area CA3 was facilitated after epileptiform activity indicating that the induced potentiation enhanced overall hippocampal network excitability. CONCLUSIONS These changes in synaptic transmission may contribute to the genesis of epilepsy and to seizure-associated memory deficits.
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Affiliation(s)
- Dominique Debanne
- Brain Research Institute, University of Zurich, Zürich, Switzerland.
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