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Lin B, Singh RK, Seiler MJ, Nasonkin IO. Survival and Functional Integration of Human Embryonic Stem Cell-Derived Retinal Organoids After Shipping and Transplantation into Retinal Degeneration Rats. Stem Cells Dev 2024; 33:201-213. [PMID: 38390839 DOI: 10.1089/scd.2023.0257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2024] Open
Abstract
Because derivation of retinal organoids (ROs) and transplantation are frequently split between geographically distant locations, we developed a special shipping device and protocol capable of the organoids' delivery to any location. Human embryonic stem cell (hESC)-derived ROs were differentiated from the hESC line H1 (WA01), shipped overnight to another location, and then transplanted into the subretinal space of blind immunodeficient retinal degeneration (RD) rats. Development of transplants was monitored by spectral-domain optical coherence tomography. Visual function was accessed by optokinetic tests and superior colliculus (SC) electrophysiology. Cryostat sections through transplants were stained with hematoxylin and eosin; or processed for immunohistochemistry to label human donor cells, retinal cell types, and synaptic markers. After transplantation, ROs integrated into the host RD retina, formed functional photoreceptors, and improved vision in rats with advanced RD. The survival and vision improvement are comparable with our previous results of hESC-ROs without a long-distance delivery. Furthermore, for the first time in the stem cell transplantation field, we demonstrated that the response heatmap on the SC showed a similar shape to the location of the transplant in the host retina, which suggested the point-to-point projection of the transplant from the retina to SC. In conclusion, our results showed that using our special device and protocol, the hESC-derived ROs can be shipped over long distance and are capable of survival and visual improvement after transplantation into the RD rats. Our data provide a proof-of-concept for stem cell replacement as a therapy for RD patients.
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Affiliation(s)
- Bin Lin
- Department of Anatomy and Neurobiology, Physical Medicine and Rehabilitation, Ophthalmology, Sue and Bill Stem Cell Research Center, University of California, Irvine School of Medicine, Irvine, California, USA
| | | | - Magdalene J Seiler
- Department of Anatomy and Neurobiology, Physical Medicine and Rehabilitation, Ophthalmology, Sue and Bill Stem Cell Research Center, University of California, Irvine School of Medicine, Irvine, California, USA
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Chancey JH, Ahmed AA, Guillén FI, Ghatpande V, Howard MA. Complex Synaptic and Intrinsic Interactions Disrupt Input/Output Functions in the Hippocampus of Scn1b Knock-Out Mice. J Neurosci 2023; 43:8562-8577. [PMID: 37845033 PMCID: PMC10711733 DOI: 10.1523/jneurosci.0786-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 09/21/2023] [Accepted: 10/03/2023] [Indexed: 10/18/2023] Open
Abstract
Pathogenic variants in SCN1B have been linked to severe developmental epileptic encephalopathies including Dravet syndrome. Scn1b knock-out (KO) mice model SCN1B loss-of-function (LOF) disorders, demonstrating seizures, developmental delays, and early death. SCN1B encodes the protein β1, an ion channel auxiliary subunit that also has roles in cell adhesion, neurite outgrowth, and gene expression. The goal of this project is to better understand of how loss of Scn1b alters information processing in the brain, resulting in seizures and associated cognitive dysfunction. Using slice electrophysiology in the CA1 region of the hippocampus from male and female Scn1b KO mice and wild-type (WT) littermates, we found that processing of physiologically relevant patterned Schaffer collateral (SC) stimulation produces larger, prolonged depolarizations and increased spiking in KO neurons compared with WTs. KO neurons exhibit enhanced intrinsic excitability, firing more action potentials with current injection. Interestingly, SC stimulation produces smaller, more facilitating excitatory and IPSCs in KO pyramidal neurons, but larger postsynaptic potentials (PSPs) with the same stimulation. We also found reduced intrinsic firing of parvalbumin (PV)-expressing interneurons and disrupted recruitment of both parvalbumin-expressing and somatostatin (SST)-expressing interneurons in response to patterned synaptic stimulation. Neuronal information processing relies on the interplay between synaptic properties, intrinsic properties that amplify or suppress incoming synaptic signals, and firing properties that produce cellular output. We found changes at each of these levels in Scn1b KO pyramidal neurons, resulting in fundamentally altered cellular information processing in the hippocampus that likely contributes to the complex phenotypes of SCN1B-linked epileptic encephalopathies.SIGNIFICANCE STATEMENT Genetic developmental epileptic encephalopathies have limited treatment options, in part because of our lack of understanding of how genetic changes result in dysfunction at the cellular and circuit levels. SCN1B is a gene linked to Dravet syndrome and other developmental epileptic encephalopathies, and Scn1b knock-out (KO) mice phenocopy the human disease, allowing us to study underlying neurophysiological changes. Here, we found changes at all levels of neuronal information processing in brains lacking Scn1b, including intrinsic excitability, synaptic properties, and synaptic integration, resulting in greatly enhanced input/output functions of the hippocampus. Our study shows that loss of Scn1b results in a complex array of cellular and network changes that fundamentally alters information processing in the hippocampus.
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Affiliation(s)
- Jessica Hotard Chancey
- Departments of Neurology and Neuroscience, Center for Learning and Memory, Dell Medical School, University of Texas at Austin, Austin, Texas 78712
| | - Alisha A Ahmed
- Departments of Neurology and Neuroscience, Center for Learning and Memory, Dell Medical School, University of Texas at Austin, Austin, Texas 78712
| | - Fernando Isaac Guillén
- Departments of Neurology and Neuroscience, Center for Learning and Memory, Dell Medical School, University of Texas at Austin, Austin, Texas 78712
| | - Vighnesh Ghatpande
- Departments of Neurology and Neuroscience, Center for Learning and Memory, Dell Medical School, University of Texas at Austin, Austin, Texas 78712
| | - MacKenzie A Howard
- Departments of Neurology and Neuroscience, Center for Learning and Memory, Dell Medical School, University of Texas at Austin, Austin, Texas 78712
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Spirou GA, Kersting M, Carr S, Razzaq B, Yamamoto Alves Pinto C, Dawson M, Ellisman MH, Manis PB. High-resolution volumetric imaging constrains compartmental models to explore synaptic integration and temporal processing by cochlear nucleus globular bushy cells. eLife 2023; 12:e83393. [PMID: 37288824 PMCID: PMC10435236 DOI: 10.7554/elife.83393] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 06/07/2023] [Indexed: 06/09/2023] Open
Abstract
Globular bushy cells (GBCs) of the cochlear nucleus play central roles in the temporal processing of sound. Despite investigation over many decades, fundamental questions remain about their dendrite structure, afferent innervation, and integration of synaptic inputs. Here, we use volume electron microscopy (EM) of the mouse cochlear nucleus to construct synaptic maps that precisely specify convergence ratios and synaptic weights for auditory nerve innervation and accurate surface areas of all postsynaptic compartments. Detailed biophysically based compartmental models can help develop hypotheses regarding how GBCs integrate inputs to yield their recorded responses to sound. We established a pipeline to export a precise reconstruction of auditory nerve axons and their endbulb terminals together with high-resolution dendrite, soma, and axon reconstructions into biophysically detailed compartmental models that could be activated by a standard cochlear transduction model. With these constraints, the models predict auditory nerve input profiles whereby all endbulbs onto a GBC are subthreshold (coincidence detection mode), or one or two inputs are suprathreshold (mixed mode). The models also predict the relative importance of dendrite geometry, soma size, and axon initial segment length in setting action potential threshold and generating heterogeneity in sound-evoked responses, and thereby propose mechanisms by which GBCs may homeostatically adjust their excitability. Volume EM also reveals new dendritic structures and dendrites that lack innervation. This framework defines a pathway from subcellular morphology to synaptic connectivity, and facilitates investigation into the roles of specific cellular features in sound encoding. We also clarify the need for new experimental measurements to provide missing cellular parameters, and predict responses to sound for further in vivo studies, thereby serving as a template for investigation of other neuron classes.
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Affiliation(s)
- George A Spirou
- Department of Medical Engineering, University of South FloridaTampaUnited States
| | - Matthew Kersting
- Department of Medical Engineering, University of South FloridaTampaUnited States
| | - Sean Carr
- Department of Medical Engineering, University of South FloridaTampaUnited States
| | - Bayan Razzaq
- Department of Otolaryngology, Head and Neck Surgery, West Virginia UniversityMorgantownUnited States
| | | | - Mariah Dawson
- Department of Otolaryngology, Head and Neck Surgery, West Virginia UniversityMorgantownUnited States
| | - Mark H Ellisman
- Department of Neurosciences, University of California, San DiegoSan DiegoUnited States
- National Center for Microscopy and Imaging Research,University of California, San DiegoSan DiegoUnited States
| | - Paul B Manis
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel HillChapel HillUnited States
- Department of Cell Biology and Physiology, University of North CarolinaChapel HillUnited States
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Mitchell DE, Miranda-Rottmann S, Blanchard M, Araya R. Altered integration of excitatory inputs onto the basal dendrites of layer 5 pyramidal neurons in a mouse model of Fragile X syndrome. Proc Natl Acad Sci U S A 2023; 120:e2208963120. [PMID: 36595706 DOI: 10.1073/pnas.2208963120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Layer 5 (L5) pyramidal neurons receive predictive and sensory inputs in a compartmentalized manner at their apical and basal dendrites, respectively. To uncover how integration of sensory inputs is affected in autism spectrum disorders (ASD), we used two-photon glutamate uncaging to activate spines in the basal dendrites of L5 pyramidal neurons from a mouse model of Fragile X syndrome (FXS), the most common genetic cause of ASD. While subthreshold excitatory inputs integrate linearly in wild-type animals, surprisingly those with FXS summate sublinearly, contradicting what would be expected of sensory hypersensitivity classically associated with ASD. We next investigated the mechanism underlying this sublinearity by performing knockdown of the regulatory β4 subunit of BK channels, which rescued the synaptic integration, a result that was corroborated with numerical simulations. Taken together, these findings suggest that there is a differential impairment in the integration of feedforward sensory and feedback predictive inputs in L5 pyramidal neurons in FXS and potentially other forms of ASD, as a result of specifically localized subcellular channelopathies. These results challenge the traditional view that FXS and other ASD are characterized by sensory hypersensitivity, proposing instead a hyposensitivity of sensory inputs and hypersensitivity of predictive inputs onto cortical neurons.
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Rindner DJ, Proddutur A, Lur G. Cell-type-specific integration of feedforward and feedback synaptic inputs in the posterior parietal cortex. Neuron 2022; 110:3760-3773.e5. [PMID: 36087582 PMCID: PMC9671855 DOI: 10.1016/j.neuron.2022.08.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 07/19/2022] [Accepted: 08/16/2022] [Indexed: 12/15/2022]
Abstract
The integration of feedforward (sensory) and feedback (top-down) neuronal signals is a principal function of the neocortex. Yet, we have limited insight into how these information streams are combined by individual neurons. Using a two-color optogenetic strategy, we found that layer 5 pyramidal neurons in the posterior parietal cortex receive monosynaptic dual innervation, combining sensory inputs with top-down signals. Subclasses of layer 5 pyramidal neurons integrated these synapses with distinct temporal dynamics. Specifically, regular spiking cells exhibited supralinear enhancement of delayed-but not coincident-inputs, while intrinsic burst-firing neurons selectively boosted coincident synaptic events. These subthreshold integration characteristics translated to a nonlinear summation of action potential firing. Complementing electrophysiology with computational modeling, we found that distinct integration profiles arose from a cell-type-specific interaction of ionic mechanisms and feedforward inhibition. These data provide insight into the cellular properties that guide the nonlinear interaction of distinct long-range afferents in the neocortex.
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Affiliation(s)
- Daniel J Rindner
- Department of Neurobiology and Behavior, University of California, Irvine, 1215 McGaugh Hall, Irvine, CA 92697, USA
| | - Archana Proddutur
- Department of Neurobiology and Behavior, University of California, Irvine, 1215 McGaugh Hall, Irvine, CA 92697, USA
| | - Gyorgy Lur
- Department of Neurobiology and Behavior, University of California, Irvine, 1215 McGaugh Hall, Irvine, CA 92697, USA.
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Menelaou E, Kishore S, McLean DL. Mixed synapses reconcile violations of the size principle in zebrafish spinal cord. eLife 2022; 11:64063. [PMID: 36166290 PMCID: PMC9514842 DOI: 10.7554/elife.64063] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 09/12/2022] [Indexed: 11/24/2022] Open
Abstract
Mixed electrical-chemical synapses potentially complicate electrophysiological interpretations of neuronal excitability and connectivity. Here, we disentangle the impact of mixed synapses within the spinal locomotor circuitry of larval zebrafish. We demonstrate that soma size is not linked to input resistance for interneurons, contrary to the biophysical predictions of the ‘size principle’ for motor neurons. Next, we show that time constants are faster, excitatory currents stronger, and mixed potentials larger in lower resistance neurons, linking mixed synapse density to resting excitability. Using a computational model, we verify the impact of weighted electrical synapses on membrane properties, synaptic integration and the low-pass filtering and distribution of coupling potentials. We conclude differences in mixed synapse density can contribute to excitability underestimations and connectivity overestimations. The contribution of mixed synaptic inputs to resting excitability helps explain ‘violations’ of the size principle, where neuron size, resistance and recruitment order are unrelated.
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Affiliation(s)
- Evdokia Menelaou
- Department of Neurobiology, Northwestern University, Evanston, United States
| | - Sandeep Kishore
- Department of Neurobiology, Northwestern University, Evanston, United States
| | - David L McLean
- Department of Neurobiology, Northwestern University, Evanston, United States
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Kriener B, Hu H, Vervaeke K. Parvalbumin interneuron dendrites enhance gamma oscillations. Cell Rep 2022; 39:110948. [PMID: 35705055 DOI: 10.1016/j.celrep.2022.110948] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 02/07/2022] [Accepted: 05/21/2022] [Indexed: 11/24/2022] Open
Abstract
Dendrites are essential determinants of the input-output relationship of single neurons, but their role in network computations is not well understood. Here, we use a combination of dendritic patch-clamp recordings and in silico modeling to determine how dendrites of parvalbumin (PV)-expressing basket cells contribute to network oscillations in the gamma frequency band. Simultaneous soma-dendrite recordings from PV basket cells in the dentate gyrus reveal that the slope, or gain, of the dendritic input-output relationship is exceptionally low, thereby reducing the cell's sensitivity to changes in its input. By simulating gamma oscillations in detailed network models, we demonstrate that the low gain is key to increase spike synchrony in PV basket cell assemblies when cells are driven by spatially and temporally heterogeneous synaptic inputs. These results highlight the role of inhibitory neuron dendrites in synchronized network oscillations.
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Affiliation(s)
- Birgit Kriener
- Institute of Basic Medical Sciences, Section of Physiology, University of Oslo, Oslo, Norway
| | - Hua Hu
- Institute of Basic Medical Sciences, Section of Physiology, University of Oslo, Oslo, Norway
| | - Koen Vervaeke
- Institute of Basic Medical Sciences, Section of Physiology, University of Oslo, Oslo, Norway.
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8
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Chancey JH, Howard MA. Synaptic Integration in CA1 Pyramidal Neurons Is Intact despite Deficits in GABAergic Transmission in the Scn1a Haploinsufficiency Mouse Model of Dravet Syndrome. eNeuro 2022; 9:ENEURO.0080-22.2022. [PMID: 35523580 PMCID: PMC9116933 DOI: 10.1523/eneuro.0080-22.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/29/2022] [Accepted: 04/27/2022] [Indexed: 01/13/2023] Open
Abstract
Mutations of SCN1A, which encodes the voltage-gated sodium channel Nav1.1, can cause epilepsy disorders such as Dravet syndrome (DS) that are comorbid with wide-ranging neurologic dysfunction. Many studies suggest that Nav1.1 haploinsufficiency causes forebrain GABAergic interneuron hypoexcitability, while pyramidal neuron physiology is mostly unaltered, and that this serves as a primary cell physiology phenotype linking mutation to disease. We hypothesized that deficits in inhibition would alter synaptic integration during activation of the hippocampal microcircuit, thus disrupting cellular information processing and leading to seizures and cognitive deficits. We tested this hypothesis using ex vivo whole-cell recordings from CA1 pyramidal neurons in a heterozygous Scn1a knock-out mouse model and wild-type (WT) littermates, measuring responses to single and patterned synaptic stimulation and spontaneous synaptic activity. Overall, our experiments reveal a surprising normalcy of excitatory and inhibitory synaptic temporal integration in the hippocampus of Scn1a haploinsufficient mice. While miniature IPSCs and feedforward inhibition and were decreased, we did not identify a pattern or frequency of input that caused a failure of synaptic inhibition. We further show that reduced GABA release probability and subsequent reduced short-term depression may act to overcome deficits in inhibition normalizing input/output functions in the Scn1a haploinsufficient hippocampus. These experiments show that CA1 pyramidal neuron synaptic processing is surprisingly robust, even during decreased interneuron function, and more complex circuit activity is likely required to reveal altered function in the hippocampal microcircuit.
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Affiliation(s)
- Jessica Hotard Chancey
- Department of Neurology, Dell Medical School, Austin 78712, TX
- Department of Neuroscience and Center for Learning and Memory, University of Texas at Austin, Austin 78712, TX
| | - MacKenzie Allen Howard
- Department of Neurology, Dell Medical School, Austin 78712, TX
- Department of Neuroscience and Center for Learning and Memory, University of Texas at Austin, Austin 78712, TX
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9
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Dembrow NC, Spain WJ. Input rate encoding and gain control in dendrites of neocortical pyramidal neurons. Cell Rep 2022; 38:110382. [PMID: 35172157 DOI: 10.1016/j.celrep.2022.110382] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 11/15/2021] [Accepted: 01/23/2022] [Indexed: 01/06/2023] Open
Abstract
Elucidating how neurons encode network activity is essential to understanding how the brain processes information. Neocortical pyramidal cells receive excitatory input onto spines distributed along dendritic branches. Local dendritic branch nonlinearities can boost the response to spatially clustered and synchronous input, but how this translates into the integration of patterns of ongoing activity remains unclear. To examine dendritic integration under naturalistic stimulus regimes, we use two-photon glutamate uncaging to repeatedly activate multiple dendritic spines at random intervals. In the proximal dendrites of two populations of layer 5 pyramidal neurons in the mouse motor cortex, spatially restricted synchrony is not a prerequisite for dendritic boosting. Branches encode afferent inputs with distinct rate sensitivities depending upon cell and branch type. Thus, inputs distributed along a dendritic branch can recruit supralinear boosting and the window of this nonlinearity may provide a mechanism by which dendrites can preferentially amplify slow-frequency network oscillations.
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Waloschková E, Gonzalez-Ramos A, Mikroulis A, Kudláček J, Andersson M, Ledri M, Kokaia M. Human Stem Cell-Derived GABAergic Interneurons Establish Efferent Synapses onto Host Neurons in Rat Epileptic Hippocampus and Inhibit Spontaneous Recurrent Seizures. Int J Mol Sci 2021; 22:ijms222413243. [PMID: 34948040 PMCID: PMC8705828 DOI: 10.3390/ijms222413243] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/03/2021] [Accepted: 12/05/2021] [Indexed: 11/17/2022] Open
Abstract
Epilepsy is a complex disorder affecting the central nervous system and is characterised by spontaneously recurring seizures (SRSs). Epileptic patients undergo symptomatic pharmacological treatments, however, in 30% of cases, they are ineffective, mostly in patients with temporal lobe epilepsy. Therefore, there is a need for developing novel treatment strategies. Transplantation of cells releasing γ-aminobutyric acid (GABA) could be used to counteract the imbalance between excitation and inhibition within epileptic neuronal networks. We generated GABAergic interneuron precursors from human embryonic stem cells (hESCs) and grafted them in the hippocampi of rats developing chronic SRSs after kainic acid-induced status epilepticus. Using whole-cell patch-clamp recordings, we characterised the maturation of the grafted cells into functional GABAergic interneurons in the host brain, and we confirmed the presence of functional inhibitory synaptic connections from grafted cells onto the host neurons. Moreover, optogenetic stimulation of grafted hESC-derived interneurons reduced the rate of epileptiform discharges in vitro. We also observed decreased SRS frequency and total time spent in SRSs in these animals in vivo as compared to non-grafted controls. These data represent a proof-of-concept that hESC-derived GABAergic neurons can exert a therapeutic effect on epileptic animals presumably through establishing inhibitory synapses with host neurons.
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Affiliation(s)
- Eliška Waloschková
- Epilepsy Center, Department of Clinical Sciences, Lund University Hospital, 221 84 Lund, Sweden; (A.G.-R.); (A.M.); (J.K.); (M.A.); (M.L.)
- Correspondence: (E.W.); (M.K.)
| | - Ana Gonzalez-Ramos
- Epilepsy Center, Department of Clinical Sciences, Lund University Hospital, 221 84 Lund, Sweden; (A.G.-R.); (A.M.); (J.K.); (M.A.); (M.L.)
| | - Apostolos Mikroulis
- Epilepsy Center, Department of Clinical Sciences, Lund University Hospital, 221 84 Lund, Sweden; (A.G.-R.); (A.M.); (J.K.); (M.A.); (M.L.)
| | - Jan Kudláček
- Epilepsy Center, Department of Clinical Sciences, Lund University Hospital, 221 84 Lund, Sweden; (A.G.-R.); (A.M.); (J.K.); (M.A.); (M.L.)
- Department of Physiology, Second Faculty of Medicine, Charles University, 150 06 Prague, Czech Republic
| | - My Andersson
- Epilepsy Center, Department of Clinical Sciences, Lund University Hospital, 221 84 Lund, Sweden; (A.G.-R.); (A.M.); (J.K.); (M.A.); (M.L.)
| | - Marco Ledri
- Epilepsy Center, Department of Clinical Sciences, Lund University Hospital, 221 84 Lund, Sweden; (A.G.-R.); (A.M.); (J.K.); (M.A.); (M.L.)
| | - Merab Kokaia
- Epilepsy Center, Department of Clinical Sciences, Lund University Hospital, 221 84 Lund, Sweden; (A.G.-R.); (A.M.); (J.K.); (M.A.); (M.L.)
- Correspondence: (E.W.); (M.K.)
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Kolpakova J, van der Vinne V, Giménez-Gómez P, Le T, You IJ, Zhao-Shea R, Velazquez-Marrero C, Tapper AR, Martin GE. Binge Alcohol Drinking Alters Synaptic Processing of Executive and Emotional Information in Core Nucleus Accumbens Medium Spiny Neurons. Front Cell Neurosci 2021; 15:742207. [PMID: 34867199 PMCID: PMC8635139 DOI: 10.3389/fncel.2021.742207] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 10/26/2021] [Indexed: 11/27/2022] Open
Abstract
The nucleus accumbens (NAc) is a forebrain region mediating the positive-reinforcing properties of drugs of abuse, including alcohol. It receives glutamatergic projections from multiple forebrain and limbic regions such as the prefrontal cortex (PFCx) and basolateral amygdala (BLA), respectively. However, it is unknown how NAc medium spiny neurons (MSNs) integrate PFCx and BLA inputs, and how this integration is affected by alcohol exposure. Because progress has been hampered by the inability to independently stimulate different pathways, we implemented a dual wavelength optogenetic approach to selectively and independently stimulate PFCx and BLA NAc inputs within the same brain slice. This approach functionally demonstrates that PFCx and BLA inputs synapse onto the same MSNs where they reciprocally inhibit each other pre-synaptically in a strict time-dependent manner. In alcohol-naïve mice, this temporal gating of BLA-inputs by PFCx afferents is stronger than the reverse, revealing that MSNs prioritize high-order executive processes information from the PFCx. Importantly, binge alcohol drinking alters this reciprocal inhibition by unilaterally strengthening BLA inhibition of PFCx inputs. In line with this observation, we demonstrate that in vivo optogenetic stimulation of the BLA, but not PFCx, blocks binge alcohol drinking escalation in mice. Overall, our results identify NAc MSNs as a key integrator of executive and emotional information and show that this integration is dysregulated during binge alcohol drinking.
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Affiliation(s)
- Jenya Kolpakova
- Department of Neurobiology, The Brudnick Neuropsychiatric Research Institute, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | | | - Pablo Giménez-Gómez
- Department of Neurobiology, The Brudnick Neuropsychiatric Research Institute, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | - Timmy Le
- Department of Neurobiology, The Brudnick Neuropsychiatric Research Institute, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | - In-Jee You
- Department of Neurobiology, The Brudnick Neuropsychiatric Research Institute, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | - Rubing Zhao-Shea
- Department of Neurobiology, The Brudnick Neuropsychiatric Research Institute, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | - Cristina Velazquez-Marrero
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, PR, United States
| | - Andrew R Tapper
- Department of Neurobiology, The Brudnick Neuropsychiatric Research Institute, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | - Gilles E Martin
- Department of Neurobiology, The Brudnick Neuropsychiatric Research Institute, University of Massachusetts Chan Medical School, Worcester, MA, United States
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Dorsett C, Philpot BD, Smith SL, Smith IT. The Impact of SST and PV Interneurons on Nonlinear Synaptic Integration in the Neocortex. eNeuro 2021; 8:ENEURO. [PMID: 34400470 DOI: 10.1523/ENEURO.0235-21.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/26/2021] [Accepted: 08/09/2021] [Indexed: 01/19/2023] Open
Abstract
Excitatory synaptic inputs arriving at the dendrites of a neuron can engage active mechanisms that nonlinearly amplify the depolarizing currents. This supralinear synaptic integration is subject to modulation by inhibition. However, the specific rules by which different subtypes of interneurons affect the modulation have remained largely elusive. To examine how inhibition influences active synaptic integration, we optogenetically manipulated the activity of the following two subtypes of interneurons: dendrite-targeting somatostatin-expressing (SST) interneurons; and perisomatic-targeting parvalbumin-expressing (PV) interneurons. In acute slices of mouse primary visual cortex, electrical stimulation evoked nonlinear synaptic integration that depended on NMDA receptors. Optogenetic activation of SST interneurons in conjunction with electrical stimulation resulted in predominantly divisive inhibitory gain control, reducing the magnitude of the supralinear response without affecting its threshold. PV interneuron activation, on the other hand, had a minimal effect on the supralinear response. Together, these results delineate the roles for SST and PV neurons in active synaptic integration. Differential effects of inhibition by SST and PV interneurons likely increase the computational capacity of the pyramidal neurons in modulating the nonlinear integration of synaptic output.
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Beniaguev D, Segev I, London M. Single cortical neurons as deep artificial neural networks. Neuron 2021; 109:2727-2739.e3. [PMID: 34380016 DOI: 10.1016/j.neuron.2021.07.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 03/04/2021] [Accepted: 06/30/2021] [Indexed: 11/17/2022]
Abstract
Utilizing recent advances in machine learning, we introduce a systematic approach to characterize neurons' input/output (I/O) mapping complexity. Deep neural networks (DNNs) were trained to faithfully replicate the I/O function of various biophysical models of cortical neurons at millisecond (spiking) resolution. A temporally convolutional DNN with five to eight layers was required to capture the I/O mapping of a realistic model of a layer 5 cortical pyramidal cell (L5PC). This DNN generalized well when presented with inputs widely outside the training distribution. When NMDA receptors were removed, a much simpler network (fully connected neural network with one hidden layer) was sufficient to fit the model. Analysis of the DNNs' weight matrices revealed that synaptic integration in dendritic branches could be conceptualized as pattern matching from a set of spatiotemporal templates. This study provides a unified characterization of the computational complexity of single neurons and suggests that cortical networks therefore have a unique architecture, potentially supporting their computational power.
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Affiliation(s)
- David Beniaguev
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
| | - Idan Segev
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem 91904, Israel; Department of Neurobiology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Michael London
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem 91904, Israel; Department of Neurobiology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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14
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Abstract
The dendrites of neocortical pyramidal neurons are excitable. However, it is unknown how synaptic inputs engage nonlinear dendritic mechanisms during sensory processing in vivo, and how they in turn influence action potential output. Here, we provide a quantitative account of the relationship between synaptic inputs, nonlinear dendritic events, and action potential output. We developed a detailed pyramidal neuron model constrained by in vivo dendritic recordings. We drive this model with realistic input patterns constrained by sensory responses measured in vivo and connectivity measured in vitro. We show mechanistically that under realistic conditions, dendritic Na+ and NMDA spikes are the major determinants of neuronal output in vivo. We demonstrate that these dendritic spikes can be triggered by a surprisingly small number of strong synaptic inputs, in some cases even by single synapses. We predict that dendritic excitability allows the 1% strongest synaptic inputs of a neuron to control the tuning of its output. Active dendrites therefore allow smaller subcircuits consisting of only a few strongly connected neurons to achieve selectivity for specific sensory features.
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Affiliation(s)
- Lea Goetz
- Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, United Kingdom
| | - Arnd Roth
- Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, United Kingdom
| | - Michael Häusser
- Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, United Kingdom
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15
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Arlt C, Häusser M. Microcircuit Rules Governing Impact of Single Interneurons on Purkinje Cell Output In Vivo. Cell Rep 2021; 30:3020-3035.e3. [PMID: 32130904 PMCID: PMC7059114 DOI: 10.1016/j.celrep.2020.02.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 01/07/2020] [Accepted: 02/03/2020] [Indexed: 01/05/2023] Open
Abstract
The functional impact of single interneurons on neuronal output in vivo and how interneurons are recruited by physiological activity patterns remain poorly understood. In the cerebellar cortex, molecular layer interneurons and their targets, Purkinje cells, receive excitatory inputs from granule cells and climbing fibers. Using dual patch-clamp recordings from interneurons and Purkinje cells in vivo, we probe the spatiotemporal interactions between these circuit elements. We show that single interneuron spikes can potently inhibit Purkinje cell output, depending on interneuron location. Climbing fiber input activates many interneurons via glutamate spillover but results in inhibition of those interneurons that inhibit the same Purkinje cell receiving the climbing fiber input, forming a disinhibitory motif. These interneuron circuits are engaged during sensory processing, creating diverse pathway-specific response functions. These findings demonstrate how the powerful effect of single interneurons on Purkinje cell output can be sculpted by various interneuron circuit motifs to diversify cerebellar computations.
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Affiliation(s)
- Charlotte Arlt
- Wolfson Institute for Biomedical Research and Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Michael Häusser
- Wolfson Institute for Biomedical Research and Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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16
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Abstract
Excitatory synaptic transmission in many neurons is mediated by two coexpressed ionotropic glutamate receptor subtypes, AMPA and NMDA receptors, that differ in kinetics, ion selectivity, and voltage-sensitivity. AMPA receptors have fast kinetics and are voltage-insensitive, while NMDA receptors have slower kinetics and increased conductance at depolarized membrane potentials. Here, we report that the voltage dependency and kinetics of NMDA receptors act synergistically to stabilize synaptic integration of EPSPs across spatial and voltage domains. Simulations of synaptic integration in simplified and morphologically realistic dendritic trees revealed that the combined presence of AMPA and NMDA conductances reduce the variability of somatic responses to spatiotemporal patterns of excitatory synaptic input presented at different initial membrane potentials and/or in different dendritic domains. This moderating effect of the NMDA conductance on synaptic integration was robust across a wide range of AMPA-to-NMDA ratios, and results from synergistic interaction of NMDA kinetics (which reduces variability across membrane potential) and voltage dependence (which favors stabilization across dendritic location). When combined with AMPA conductance, the NMDA conductance compensates for voltage-dependent and impedance-dependent changes in synaptic driving force, and distance-dependent attenuation of synaptic potentials arriving at the axon, to increase the fidelity of synaptic integration and EPSP-spike coupling across both neuron state (i.e., initial membrane potential) and dendritic location of synaptic input. Thus, synaptic NMDA receptors convey advantages for synaptic integration that are independent of, but fully compatible with, their importance for coincidence detection and synaptic plasticity.
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17
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Prager EM, Dorman DB, Hobel ZB, Malgady JM, Blackwell KT, Plotkin JL. Dopamine Oppositely Modulates State Transitions in Striosome and Matrix Direct Pathway Striatal Spiny Neurons. Neuron 2020; 108:1091-1102.e5. [PMID: 33080228 PMCID: PMC7769890 DOI: 10.1016/j.neuron.2020.09.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 07/29/2020] [Accepted: 09/21/2020] [Indexed: 12/18/2022]
Abstract
Corticostriatal synaptic integration is partitioned among striosome (patch) and matrix compartments of the dorsal striatum, allowing compartmentalized control of discrete aspects of behavior. Despite the significance of such organization, it's unclear how compartment-specific striatal output is dynamically achieved, particularly considering new evidence that overlap of afferents is substantial. We show that dopamine oppositely shapes responses to convergent excitatory inputs in mouse striosome and matrix striatal spiny projection neurons (SPNs). Activation of postsynaptic D1 dopamine receptors promoted the generation of long-lasting synaptically evoked "up-states" in matrix SPNs but opposed it in striosomes, which were more excitable under basal conditions. Differences in dopaminergic modulation were mediated, in part, by dendritic voltage-gated calcium channels (VGCCs): pharmacological manipulation of L-type VGCCs reversed compartment-specific responses to D1 receptor activation. These results support a novel mechanism for the selection of striatal circuit components, where fluctuating levels of dopamine shift the balance of compartment-specific striatal output.
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Affiliation(s)
- Eric M Prager
- Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA
| | - Daniel B Dorman
- Interdisciplinary Program in Neuroscience, George Mason University, Fairfax, VA 22030, USA
| | - Zachary B Hobel
- Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA
| | - Jeffrey M Malgady
- Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA
| | - Kim T Blackwell
- Interdisciplinary Program in Neuroscience, George Mason University, Fairfax, VA 22030, USA; Bioengineering Department, Volgenau School of Engineering, George Mason University, Fairfax, VA 22030, USA
| | - Joshua L Plotkin
- Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University School of Medicine, Stony Brook, NY 11794, USA.
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18
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McCauley JP, Petroccione MA, D'Brant LY, Todd GC, Affinnih N, Wisnoski JJ, Zahid S, Shree S, Sousa AA, De Guzman RM, Migliore R, Brazhe A, Leapman RD, Khmaladze A, Semyanov A, Zuloaga DG, Migliore M, Scimemi A. Circadian Modulation of Neurons and Astrocytes Controls Synaptic Plasticity in Hippocampal Area CA1. Cell Rep 2020; 33:108255. [PMID: 33053337 PMCID: PMC7700820 DOI: 10.1016/j.celrep.2020.108255] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 08/21/2020] [Accepted: 09/18/2020] [Indexed: 12/18/2022] Open
Abstract
Most animal species operate according to a 24-h period set by the suprachiasmatic nucleus (SCN) of the hypothalamus. The rhythmic activity of the SCN modulates hippocampal-dependent memory, but the molecular and cellular mechanisms that account for this effect remain largely unknown. Here, we identify cell-type-specific structural and functional changes that occur with circadian rhythmicity in neurons and astrocytes in hippocampal area CA1. Pyramidal neurons change the surface expression of NMDA receptors. Astrocytes change their proximity to synapses. Together, these phenomena alter glutamate clearance, receptor activation, and integration of temporally clustered excitatory synaptic inputs, ultimately shaping hippocampal-dependent learning in vivo. We identify corticosterone as a key contributor to changes in synaptic strength. These findings highlight important mechanisms through which neurons and astrocytes modify the molecular composition and structure of the synaptic environment, contribute to the local storage of information in the hippocampus, and alter the temporal dynamics of cognitive processing.
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Affiliation(s)
- John P McCauley
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | | | - Lianna Y D'Brant
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA; Department of Physics, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Gabrielle C Todd
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Nurat Affinnih
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Justin J Wisnoski
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Shergil Zahid
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Swasti Shree
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA; Bethlehem Central High School, 700 Delaware Avenue, Delmar, NY 12054, USA
| | - Alioscka A Sousa
- Federal University of São Paulo, Department of Biochemistry, 100 Rua Tres de Maio, São Paulo 04044-020, Brazil; National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Rose M De Guzman
- Department of Psychology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Rosanna Migliore
- Institute of Biophysics, National Research Council, 153 Via Ugo La Malfa, Palermo 90146, Italy
| | - Alexey Brazhe
- Department of Biophysics, Lomonosov Moscow State University, Leninskie Gory 1/12, Moscow 119234, Russia; Department of Molecular Neurobiology, Institute of Bioorganic Chemistry, Ulitsa Miklukho-Maklaya 16/10, Moscow 117997, Russia
| | - Richard D Leapman
- National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Alexander Khmaladze
- Department of Physics, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Alexey Semyanov
- Department of Molecular Neurobiology, Institute of Bioorganic Chemistry, Ulitsa Miklukho-Maklaya 16/10, Moscow 117997, Russia; Sechenov First Moscow State Medical University, Bolshaya Pirogovskaya Ulitsa 19с1, Moscow 119146, Russia
| | - Damian G Zuloaga
- Department of Psychology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Michele Migliore
- Institute of Biophysics, National Research Council, 153 Via Ugo La Malfa, Palermo 90146, Italy
| | - Annalisa Scimemi
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA.
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19
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Abstract
The first patch-clamp recordings from the dendrites of human neocortical neurons have recently been reported by Beaulieu-Laroche et al. and Gidon et al. These studies have shown that human dendrites are electrically excitable, exhibiting backpropagating action potentials and fast dendritic calcium spikes. This new frontier highlights the potential for interspecies differences in the biophysics of dendritic computation.
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Affiliation(s)
- Mehmet Fişek
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London, WC1E 6BT, UK; Department of Neuroscience, Physiology, and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Michael Häusser
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London, WC1E 6BT, UK; Department of Neuroscience, Physiology, and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
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20
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Masurkar AV, Tian C, Warren R, Reyes I, Lowes DC, Brann DH, Siegelbaum SA. Postsynaptic integrative properties of dorsal CA1 pyramidal neuron subpopulations. J Neurophysiol 2020; 123:980-992. [PMID: 31967926 PMCID: PMC7099474 DOI: 10.1152/jn.00397.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 01/21/2020] [Accepted: 01/21/2020] [Indexed: 11/22/2022] Open
Abstract
The population activity of CA1 pyramidal neurons (PNs) segregates along anatomical axes with different behaviors, suggesting that CA1 PNs are functionally subspecialized based on somatic location. In dorsal CA1, spatial encoding is biased toward CA2 (CA1c) and in deep layers of the radial axis. In contrast, nonspatial coding peaks toward subiculum (CA1a) and in superficial layers. While preferential innervation by spatial vs. nonspatial input from entorhinal cortex (EC) may contribute to this specialization, it cannot fully explain the range of in vivo responses. Differences in intrinsic properties thus may play a critical role in modulating such synaptic input differences. In this study we examined the postsynaptic integrative properties of dorsal CA1 PNs in six subpopulations along the transverse (CA1c, CA1b, CA1a) and radial (deep, superficial) axes. Our results suggest that active and passive properties of deep and superficial neurons evolve over the transverse axis to promote the functional specialization of CA1c vs. CA1a as dictated by their cortical input. We also find that CA1b is not merely an intermediate mix of its neighbors, but uniquely balances low excitability with superior input integration of its mixed input, as may be required for its proposed role in sequence encoding. Thus synaptic input and intrinsic properties combine to functionally compartmentalize CA1 processing into at least three transverse axis regions defined by the processing schemes of their composite radial axis subpopulations.NEW & NOTEWORTHY There is increasing interest in CA1 pyramidal neuron heterogeneity and the functional relevance of this diversity. We find that active and passive properties evolve over the transverse and radial axes in dorsal CA1 to promote the functional specialization of CA1c and CA1a for spatial and nonspatial memory, respectively. Furthermore, CA1b is not a mean of its neighbors, but features low excitability and superior integrative capabilities, relevant to its role in nonspatial sequence encoding.
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Affiliation(s)
- Arjun V Masurkar
- Center for Cognitive Neurology, Department of Neurology, New York University School of Medicine, New York, New York
| | - Chengju Tian
- Center for Cognitive Neurology, Department of Neurology, New York University School of Medicine, New York, New York
| | - Richard Warren
- Department of Neuroscience, Columbia University, New York, New York
| | - Isabel Reyes
- Center for Cognitive Neurology, Department of Neurology, New York University School of Medicine, New York, New York
| | - Daniel C Lowes
- Department of Neuroscience, Columbia University, New York, New York
| | - David H Brann
- Department of Neuroscience, Columbia University, New York, New York
| | - Steven A Siegelbaum
- Department of Neuroscience, Columbia University, New York, New York
- Department of Pharmacology, Columbia University, New York, New York
- Kavli Institute for Brain Science, Columbia University, New York, New York
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21
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Fore TR, Taylor BN, Brunel N, Hull C. Acetylcholine Modulates Cerebellar Granule Cell Spiking by Regulating the Balance of Synaptic Excitation and Inhibition. J Neurosci 2020; 40:2882-94. [PMID: 32111698 DOI: 10.1523/JNEUROSCI.2148-19.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 02/03/2020] [Accepted: 02/20/2020] [Indexed: 12/20/2022] Open
Abstract
Sensorimotor integration in the cerebellum is essential for refining motor output, and the first stage of this processing occurs in the granule cell layer. Recent evidence suggests that granule cell layer synaptic integration can be contextually modified, although the circuit mechanisms that could mediate such modulation remain largely unknown. Here we investigate the role of ACh in regulating granule cell layer synaptic integration in male rats and mice of both sexes. We find that Golgi cells, interneurons that provide the sole source of inhibition to the granule cell layer, express both nicotinic and muscarinic cholinergic receptors. While acute ACh application can modestly depolarize some Golgi cells, the net effect of longer, optogenetically induced ACh release is to strongly hyperpolarize Golgi cells. Golgi cell hyperpolarization by ACh leads to a significant reduction in both tonic and evoked granule cell synaptic inhibition. ACh also reduces glutamate release from mossy fibers by acting on presynaptic muscarinic receptors. Surprisingly, despite these consistent effects on Golgi cells and mossy fibers, ACh can either increase or decrease the spike probability of granule cells as measured by noninvasive cell-attached recordings. By constructing an integrate-and-fire model of granule cell layer population activity, we find that the direction of spike rate modulation can be accounted for predominately by the initial balance of excitation and inhibition onto individual granule cells. Together, these experiments demonstrate that ACh can modulate population-level granule cell responses by altering the ratios of excitation and inhibition at the first stage of cerebellar processing.SIGNIFICANCE STATEMENT The cerebellum plays a key role in motor control and motor learning. While it is known that behavioral context can modify motor learning, the circuit basis of such modulation has remained unclear. Here we find that a key neuromodulator, ACh, can alter the balance of excitation and inhibition at the first stage of cerebellar processing. These results suggest that ACh could play a key role in altering cerebellar learning by modifying how sensorimotor input is represented at the input layer of the cerebellum.
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22
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Pastoll H, Garden DL, Papastathopoulos I, Sürmeli G, Nolan MF. Inter- and intra-animal variation in the integrative properties of stellate cells in the medial entorhinal cortex. eLife 2020; 9:52258. [PMID: 32039761 PMCID: PMC7067584 DOI: 10.7554/elife.52258] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 02/04/2020] [Indexed: 01/28/2023] Open
Abstract
Distinctions between cell types underpin organizational principles for nervous system function. Functional variation also exists between neurons of the same type. This is exemplified by correspondence between grid cell spatial scales and the synaptic integrative properties of stellate cells (SCs) in the medial entorhinal cortex. However, we know little about how functional variability is structured either within or between individuals. Using ex-vivo patch-clamp recordings from up to 55 SCs per mouse, we found that integrative properties vary between mice and, in contrast to the modularity of grid cell spatial scales, have a continuous dorsoventral organization. Our results constrain mechanisms for modular grid firing and provide evidence for inter-animal phenotypic variability among neurons of the same type. We suggest that neuron type properties are tuned to circuit-level set points that vary within and between animals.
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Affiliation(s)
- Hugh Pastoll
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Derek L Garden
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ioannis Papastathopoulos
- The Alan Turing Institute, London, United States.,School of Mathematics, Maxwell Institute and Centre for Statistics, University of Edinburgh, Edinburgh, United Kingdom
| | - Gülşen Sürmeli
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Matthew F Nolan
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
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23
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Song JH, Lucaci D, Calangiu I, Brown MTC, Park JS, Kim J, Brickley SG, Chadderton P. Combining mGRASP and Optogenetics Enables High-Resolution Functional Mapping of Descending Cortical Projections. Cell Rep 2018; 24:1071-80. [PMID: 30044974 DOI: 10.1016/j.celrep.2018.06.076] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 03/23/2018] [Accepted: 06/18/2018] [Indexed: 11/25/2022] Open
Abstract
We have applied optogenetics and mGRASP, a light microscopy technique that labels synaptic contacts, to map the number and strength of defined corticocollicular (CC) connections. Using mGRASP, we show that CC projections form small, medium, and large synapses, and both the number and the distribution of synapse size vary among the IC regions. Using optogenetics, we show that low-frequency stimulation of CC axons expressing channelrhodopsin produces prolonged elevations of the CC miniature EPSC (mEPSC) rate. Functional analysis of CC mEPSCs reveals small-, medium-, and large-amplitude events that mirror the synaptic distributions observed with mGRASP. Our results reveal that descending ipsilateral projections dominate CC feedback via an increased number of large synaptic contacts, especially onto the soma of IC neurons. This study highlights the feasibility of combining microscopy (i.e., mGRASP) and optogenetics to reveal synaptic weighting of defined projections at the level of single neurons, enabling functional connectomic mapping in diverse neural circuits. Optogenetic axonal stimulation causes prolonged increases in quantal synaptic release Quantal and anatomical measures of synapse strength directly correspond Strength and cellular location of cortical inputs to midbrain are region specific
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24
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Parra A, Baker CA, Bolton MM. Regional Specialization of Pyramidal Neuron Morphology and Physiology in the Tree Shrew Neocortex. Cereb Cortex 2019; 29:4488-4505. [PMID: 30715235 DOI: 10.1093/cercor/bhy326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 10/12/2018] [Accepted: 12/07/2018] [Indexed: 01/08/2023] Open
Abstract
The mammalian cerebral cortex is divided into different areas according to their function and pattern of connections. Studies comparing primary visual (V1) and prefrontal cortex (PFC) of primates have demonstrated striking pyramidal neuron (PN) specialization not present in comparable areas of the mouse neocortex. To better understand PFC evolution and regional PN specialization, we studied the tree shrew, a species with a close phylogenetic relationship to primates. We defined the tree shrew PFC based on cytoarchitectonic borders, thalamic connectivity and characterized the morphology and electrophysiology of layer II/III PNs in V1 and PFC. Similar to primates, the PFC PNs in the tree shrew fire with a regular spiking pattern and have larger dendritic tree and spines than those in V1. However, V1 PNs showed strikingly large basal dendritic arbors with high spine density, firing at higher rates and in a more varied pattern than PFC PNs. Yet, unlike in the mouse and unreported in the primate, medial prefrontal PN are more easily recruited than either the dorsolateral or V1 neurons. This specialization of PN morphology and physiology is likely to be a significant factor in the evolution of cortex, contributing to differences in the computational capacities of individual cortical areas.
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Affiliation(s)
- Andres Parra
- Disorders of Neural Circuit Function, Max Planck Florida Institute for Neuroscience, Jupiter, USA.,Functional Architecture of the Cerebral Cortex, Max Planck Florida Institute for Neuroscience, Jupiter, USA.,Cellular and Systems Neurobiology, Instituto de Neurociencias de Alicante, Alicante, Spain
| | - Christopher A Baker
- Disorders of Neural Circuit Function, Max Planck Florida Institute for Neuroscience, Jupiter, USA
| | - M McLean Bolton
- Disorders of Neural Circuit Function, Max Planck Florida Institute for Neuroscience, Jupiter, USA
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25
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Poleg-Polsky A. Dendritic Spikes Expand the Range of Well Tolerated Population Noise Structures. J Neurosci 2019; 39:9173-84. [PMID: 31558617 DOI: 10.1523/JNEUROSCI.0638-19.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 08/08/2019] [Accepted: 09/14/2019] [Indexed: 12/11/2022] Open
Abstract
The brain operates surprisingly well despite the noisy nature of individual neurons. The central mechanism for noise mitigation in the nervous system is thought to involve averaging over multiple noise-corrupted inputs. Subsequently, there has been considerable interest in identifying noise structures that can be integrated linearly in a way that preserves reliable signal encoding. By analyzing realistic synaptic integration in biophysically accurate neuronal models, I report a complementary denoising approach that is mediated by focal dendritic spikes. Dendritic spikes might seem to be unlikely candidates for noise reduction due to their miniscule integration compartments and poor averaging abilities. Nonetheless, the extra thresholding step introduced by dendritic spike generation increases neuronal tolerance for a broad category of noise structures, some of which cannot be resolved well with averaging. This property of active dendrites compensates for compartment size constraints and expands the repertoire of conditions that can be processed by neuronal populations.SIGNIFICANCE STATEMENT Noise, or random variability, is a prominent feature of the neuronal code and poses a fundamental challenge for information processing. To reconcile the surprisingly accurate output of the brain with the inherent noisiness of biological systems, previous work examined signal integration in idealized neurons. The notion that emerged from this body of work is that accurate signal representation relies largely on input averaging in neuronal dendrites. In contrast to the prevailing view, I show that denoising in simulated neurons with realistic morphology and biophysical properties follows a different strategy: dendritic spikes act as classifiers that assist in extracting information from a variety of noise structures that have been considered before to be particularly disruptive for reliable brain function.
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26
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Abstract
Modeling single-neuron dynamics is the first step to quantitatively understand brain computation. Yet, the existing point neuron models fail to capture dendritic effects, which are crucial for neuronal information processing. We derive an effective point neuron model, which incorporates an additional synaptic integration current arising from the nonlinear interaction between synaptic currents across spatial dendrites. Our model captures the somatic voltage response of a neuron with complex dendrites and is capable of performing rich dendritic computations. Besides its computational efficiency in simulations, our model suggests reexamination of previous studies involving the decomposition of excitatory and inhibitory synaptic inputs based on the existing point neuron framework, e.g., the inhibition is often underestimated in experiment. Complex dendrites in general present formidable challenges to understanding neuronal information processing. To circumvent the difficulty, a prevalent viewpoint simplifies the neuronal morphology as a point representing the soma, and the excitatory and inhibitory synaptic currents originated from the dendrites are treated as linearly summed at the soma. Despite its extensive applications, the validity of the synaptic current description remains unclear, and the existing point neuron framework fails to characterize the spatiotemporal aspects of dendritic integration supporting specific computations. Using electrophysiological experiments, realistic neuronal simulations, and theoretical analyses, we demonstrate that the traditional assumption of linear summation of synaptic currents is oversimplified and underestimates the inhibition effect. We then derive a form of synaptic integration current within the point neuron framework to capture dendritic effects. In the derived form, the interaction between each pair of synaptic inputs on the dendrites can be reliably parameterized by a single coefficient, suggesting the inherent low-dimensional structure of dendritic integration. We further generalize the form of synaptic integration current to capture the spatiotemporal interactions among multiple synaptic inputs and show that a point neuron model with the synaptic integration current incorporated possesses the computational ability of a spatial neuron with dendrites, including direction selectivity, coincidence detection, logical operation, and a bilinear dendritic integration rule discovered in experiment. Our work amends the modeling of synaptic inputs and improves the computational power of a modeling neuron within the point neuron framework.
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27
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OBI-NAGATA K, TEMMA Y, HAYASHI-TAKAGI A. Synaptic functions and their disruption in schizophrenia: From clinical evidence to synaptic optogenetics in an animal model. Proc Jpn Acad Ser B Phys Biol Sci 2019; 95:179-197. [PMID: 31080187 PMCID: PMC6742729 DOI: 10.2183/pjab.95.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The adult human brain consists of approximately a hundred billion neurons, which are connected via synapses. The pattern and strength of the synaptic connections are constantly changing (synaptic plasticity), and these changes are considered to underlie learning, memory, and personality. Many psychiatric disorders have been related to disturbances in synaptogenesis and subsequent plasticity. In this review, we summarize findings of synaptic disturbance and its involvement in the pathogenesis and/or pathophysiology of psychiatric disorders. We will focus on schizophrenia, because this condition has a high proven heritability, which offers more unambiguous insights into the biological origins of not only schizophrenia but also related psychiatric disorders. To demonstrate the involvement of synaptopathy in psychiatric disorders, we discuss what knowledge is missing at the circuits level, and what new technologies are needed to achieve a comprehensive understanding of synaptopathy in psychiatric disorders.
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Affiliation(s)
- Kisho OBI-NAGATA
- Laboratory of Medical Neuroscience, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Yusuke TEMMA
- Laboratory of Medical Neuroscience, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Akiko HAYASHI-TAKAGI
- Laboratory of Medical Neuroscience, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Japan
- Correspondence should be addressed: A. Hayashi-Takagi, Laboratory of Medical Neuroscience, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi, Gunma 371-8512, Japan (e-mail: )
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28
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Abstract
Understanding how afferent information is integrated by cortical structures requires identifying the factors shaping excitation and inhibition within their input layers. The input layer of the cerebellar cortex integrates diverse sensorimotor information to enable learned associations that refine the dynamics of movement. Specifically, mossy fiber afferents relay sensorimotor input into the cerebellum to excite granule cells, whose activity is regulated by inhibitory Golgi cells. To test how this integration can be modulated, we have used an acute brain slice preparation from young adult rats and found that encoding of mossy fiber input in the cerebellar granule cell layer can be regulated by serotonin (5-hydroxytryptamine, 5-HT) via a specific action on Golgi cells. We find that 5-HT depolarizes Golgi cells, likely by activating 5-HT2A receptors, but does not directly act on either granule cells or mossy fibers. As a result of Golgi cell depolarization, 5-HT significantly increases tonic inhibition onto both granule cells and Golgi cells. 5-HT-mediated Golgi cell depolarization is not sufficient, however, to alter the probability or timing of mossy fiber-evoked feed-forward inhibition onto granule cells. Together, increased granule cell tonic inhibition paired with normal feed-forward inhibition acts to reduce granule cell spike probability without altering spike timing. Hence, these data provide a circuit mechanism by which 5-HT can reduce granule cell activity without altering temporal representations of mossy fiber input. Such changes in network integration could enable flexible, state-specific suppression of cerebellar sensorimotor input that should not be learned or enable reversal learning for unwanted associations. NEW & NOTEWORTHY Serotonin (5-hydroxytryptamine, 5-HT) regulates synaptic integration at the input stage of cerebellar processing by increasing tonic inhibition of granule cells. This circuit mechanism reduces the probability of granule cell spiking without altering spike timing, thus suppressing cerebellar input without altering its temporal representation in the granule cell layer.
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Affiliation(s)
- Elizabeth Fleming
- Department of Neurobiology, Duke University Medical School , Durham, North Carolina
| | - Court Hull
- Department of Neurobiology, Duke University Medical School , Durham, North Carolina
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29
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Rongala UB, Spanne A, Mazzoni A, Bengtsson F, Oddo CM, Jörntell H. Intracellular Dynamics in Cuneate Nucleus Neurons Support Self-Stabilizing Learning of Generalizable Tactile Representations. Front Cell Neurosci 2018; 12:210. [PMID: 30108485 PMCID: PMC6079306 DOI: 10.3389/fncel.2018.00210] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 06/26/2018] [Indexed: 12/12/2022] Open
Abstract
How the brain represents the external world is an unresolved issue for neuroscience, which could provide fundamental insights into brain circuitry operation and solutions for artificial intelligence and robotics. The neurons of the cuneate nucleus form the first interface for the sense of touch in the brain. They were previously shown to have a highly skewed synaptic weight distribution for tactile primary afferent inputs, suggesting that their connectivity is strongly shaped by learning. Here we first characterized the intracellular dynamics and inhibitory synaptic inputs of cuneate neurons in vivo and modeled their integration of tactile sensory inputs. We then replaced the tactile inputs with input from a sensorized bionic fingertip and modeled the learning-induced representations that emerged from varied sensory experiences. The model reproduced both the intrinsic membrane dynamics and the synaptic weight distributions observed in cuneate neurons in vivo. In terms of higher level model properties, individual cuneate neurons learnt to identify specific sets of correlated sensors, which at the population level resulted in a decomposition of the sensor space into its recurring high-dimensional components. Such vector components could be applied to identify both past and novel sensory experiences and likely correspond to the fundamental haptic input features these neurons encode in vivo. In addition, we show that the cuneate learning architecture is robust to a wide range of intrinsic parameter settings due to the neuronal intrinsic dynamics. Therefore, the architecture is a potentially generic solution for forming versatile representations of the external world in different sensor systems.
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Affiliation(s)
- Udaya B Rongala
- The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Anton Spanne
- Section for Neurobiology, Department of Experimental Medical Sciences, Biomedical Center, Lund University, Lund, Sweden
| | - Alberto Mazzoni
- The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Fredrik Bengtsson
- Section for Neurobiology, Department of Experimental Medical Sciences, Biomedical Center, Lund University, Lund, Sweden
| | - Calogero M Oddo
- The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Henrik Jörntell
- Section for Neurobiology, Department of Experimental Medical Sciences, Biomedical Center, Lund University, Lund, Sweden
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30
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Alcami P. Electrical Synapses Enhance and Accelerate Interneuron Recruitment in Response to Coincident and Sequential Excitation. Front Cell Neurosci 2018; 12:156. [PMID: 29973871 PMCID: PMC6020792 DOI: 10.3389/fncel.2018.00156] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 05/17/2018] [Indexed: 01/17/2023] Open
Abstract
Electrical synapses are ubiquitous in interneuron networks. They form intercellular pathways, allowing electrical currents to leak between coupled interneurons. I explored the impact of electrical coupling on the integration of excitatory signals and on the coincidence detection abilities of electrically-coupled cerebellar basket cells (BCs). In order to do so, I quantified the influence of electrical coupling on the rate, the probability and the latency at which BCs generate action potentials when stimulated. The long-lasting simultaneous suprathreshold depolarization of a coupled cell evoked an increase in firing rate and a shortening of action potential latency in a reference basket cell, compared to its depolarization alone. Likewise, the action potential probability of coupled cells was strongly increased when they were simultaneously stimulated with trains of short-duration near-threshold current pulses (mimicking the activation of presynaptic granule cells) at 10 Hz, and to a lesser extent at 50 Hz, an effect that was absent in non-coupled cells. Moreover, action potential probability was increased and action potential latency was shortened in response to synaptic stimulations in mice lacking the protein that forms gap junctions between BCs, connexin36, relative to wild-type (WT) controls. These results suggest that electrical synapses between BCs decrease the probability and increase the latency of stimulus-triggered action potentials, both effects being reverted upon simultaneous excitation of coupled cells. Interestingly, varying the delay at which coupled cells are stimulated revealed that the probability and the speed of action potential generation are facilitated maximally when a basket cell is stimulated shortly after a coupled cell. These findings suggest that electrically-coupled interneurons behave as coincidence and sequence detectors that dynamically regulate the latency and the strength of inhibition onto postsynaptic targets depending on the degree of input synchrony in the coupled interneuron network.
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Affiliation(s)
- Pepe Alcami
- Laboratoire de Physiologie Cérébrale, Unité Mixte de Recherche UMR8118, Université Paris Descartes and Centre National de la Recherche Scientifique, Paris, France.,Laboratory of Cellular and Systemic Neurophysiology, Institute for Physiology I, Albert-Ludwigs University Freiburg, Freiburg, Germany.,Grass Laboratory, Marine Biological Laboratory, Woods Hole, MA, United States.,Department of Behavioural Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany
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31
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Hsu CL, Zhao X, Milstein AD, Spruston N. Persistent Sodium Current Mediates the Steep Voltage Dependence of Spatial Coding in Hippocampal Pyramidal Neurons. Neuron 2018; 99:147-162.e8. [PMID: 29909995 DOI: 10.1016/j.neuron.2018.05.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 04/13/2018] [Accepted: 05/14/2018] [Indexed: 01/19/2023]
Abstract
The mammalian hippocampus forms a cognitive map using neurons that fire according to an animal's position ("place cells") and many other behavioral and cognitive variables. The responses of these neurons are shaped by their presynaptic inputs and the nature of their postsynaptic integration. In CA1 pyramidal neurons, spatial responses in vivo exhibit a strikingly supralinear dependence on baseline membrane potential. The biophysical mechanisms underlying this nonlinear cellular computation are unknown. Here, through a combination of in vitro, in vivo, and in silico approaches, we show that persistent sodium current mediates the strong membrane potential dependence of place cell activity. This current operates at membrane potentials below the action potential threshold and over seconds-long timescales, mediating a powerful and rapidly reversible amplification of synaptic responses, which drives place cell firing. Thus, we identify a biophysical mechanism that shapes the coding properties of neurons composing the hippocampal cognitive map.
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Affiliation(s)
- Ching-Lung Hsu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Xinyu Zhao
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Aaron D Milstein
- Neurosurgery Department, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Nelson Spruston
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
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32
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Krzisch M, Fülling C, Jabinet L, Armida J, Gebara E, Cassé F, Habbas S, Volterra A, Hornung JP, Toni N. Synaptic Adhesion Molecules Regulate the Integration of New Granule Neurons in the Postnatal Mouse Hippocampus and their Impact on Spatial Memory. Cereb Cortex 2018; 27:4048-4059. [PMID: 27473321 DOI: 10.1093/cercor/bhw217] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 06/21/2016] [Indexed: 11/14/2022] Open
Abstract
Postnatal hippocampal neurogenesis induces network remodeling and may participate to mechanisms of learning. In turn, the maturation and survival of newborn neurons is regulated by their activity. Here, we tested the effect of a cell-autonomous overexpression of synaptic adhesion molecules on the maturation and survival of neurons born postnatally and on hippocampal-dependent memory performances. Families of adhesion molecules are known to induce pre- and post-synaptic assembly. Using viral targeting, we overexpressed three different synaptic adhesion molecules, SynCAM1, Neuroligin-1B and Neuroligin-2A in newborn neurons in the dentate gyrus of 7- to 9-week-old mice. We found that SynCAM1 increased the morphological maturation of dendritic spines and mossy fiber terminals while Neuroligin-1B increased spine density. In contrast, Neuroligin-2A increased both spine density and size as well as GABAergic innervation and resulted in a drastic increase of neuronal survival. Surprisingly, despite increased neurogenesis, mice overexpressing Neuroligin-2A in new neurons showed decreased memory performances in a Morris water maze task. These results indicate that the cell-autonomous overexpression of synaptic adhesion molecules can enhance different aspects of synapse formation on new neurons and increase their survival. Furthermore, they suggest that the mechanisms by which new neurons integrate in the postnatal hippocampus conditions their functional implication in learning and memory.
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Affiliation(s)
- Marine Krzisch
- Department of Fundamental Neurosciences, University of Lausanne, 9, rue du Bugnon, Lausanne, Switzerland
| | - Christine Fülling
- Department of Fundamental Neurosciences, University of Lausanne, 9, rue du Bugnon, Lausanne, Switzerland
| | - Laura Jabinet
- Department of Fundamental Neurosciences, University of Lausanne, 9, rue du Bugnon, Lausanne, Switzerland
| | - Jan Armida
- Department of Fundamental Neurosciences, University of Lausanne, 9, rue du Bugnon, Lausanne, Switzerland
| | - Elias Gebara
- Department of Fundamental Neurosciences, University of Lausanne, 9, rue du Bugnon, Lausanne, Switzerland
| | - Frédéric Cassé
- Department of Fundamental Neurosciences, University of Lausanne, 9, rue du Bugnon, Lausanne, Switzerland
| | - Samia Habbas
- Department of Fundamental Neurosciences, University of Lausanne, 9, rue du Bugnon, Lausanne, Switzerland
| | - Andrea Volterra
- Department of Fundamental Neurosciences, University of Lausanne, 9, rue du Bugnon, Lausanne, Switzerland
| | - Jean-Pierre Hornung
- Department of Fundamental Neurosciences, University of Lausanne, 9, rue du Bugnon, Lausanne, Switzerland
| | - Nicolas Toni
- Department of Fundamental Neurosciences, University of Lausanne, 9, rue du Bugnon, Lausanne, Switzerland
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33
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Groschner LN, Chan Wah Hak L, Bogacz R, DasGupta S, Miesenböck G. Dendritic Integration of Sensory Evidence in Perceptual Decision-Making. Cell 2018; 173:894-905.e13. [PMID: 29706545 DOI: 10.1016/j.cell.2018.03.075] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/30/2018] [Accepted: 03/28/2018] [Indexed: 12/11/2022]
Abstract
Perceptual decisions require the accumulation of sensory information to a response criterion. Most accounts of how the brain performs this process of temporal integration have focused on evolving patterns of spiking activity. We report that subthreshold changes in membrane voltage can represent accumulating evidence before a choice. αβ core Kenyon cells (αβc KCs) in the mushroom bodies of fruit flies integrate odor-evoked synaptic inputs to action potential threshold at timescales matching the speed of olfactory discrimination. The forkhead box P transcription factor (FoxP) sets neuronal integration and behavioral decision times by controlling the abundance of the voltage-gated potassium channel Shal (KV4) in αβc KC dendrites. αβc KCs thus tailor, through a particular constellation of biophysical properties, the generic process of synaptic integration to the demands of sequential sampling.
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34
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Lu Y, Liu Y, Curry RJ. Activity-dependent synaptic integration and modulation of bilateral excitatory inputs in an auditory coincidence detection circuit. J Physiol 2018; 596:1981-1997. [PMID: 29572827 DOI: 10.1113/jp275735] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/05/2018] [Indexed: 02/05/2023] Open
Abstract
KEY POINTS Binaural excitatory inputs to coincidence detection neurons in nucleus laminaris (NL) play essential roles in interaural time difference coding for sound localization. Here, we show that the two excitatory inputs are physiologically nearly completely segregated. Synaptic integration shows linear summation of EPSPs, ensuring high efficiency of coincidence detection of the bilateral excitatory inputs. We further show that the two excitatory inputs to single NL neurons are symmetrical in synaptic strength, kinetics and short-term plasticity. Modulation of the EPSCs by metabotropic glutamate receptors (mGluRs) is identical between the two excitatory inputs, maintaining balanced bilateral excitation under neuromodulatory conditions. Unilateral hearing deprivation reduces synaptic excitation and paradoxically strengthens mGluR modulation of EPSCs, suggesting activity-dependent anti-homeostatic regulation, a novel synaptic plasticity in response to sensory manipulations. ABSTRACT Neurons in the avian nucleus laminaris (NL) receive bilateral excitatory inputs from the cochlear nucleus magnocellularis, via morphologically symmetrical dorsal (ipsilateral) and ventral (contralateral) dendrites. Using in vitro whole-cell patch recordings in chicken brainstem slices, we investigated synaptic integration and modulation of the bilateral inputs to NL under normal and hearing deprivation conditions. We found that the two excitatory inputs onto single NL neurons were nearly completely segregated, and integration of the two inputs was linear for EPSPs. The two inputs had similar synaptic strength, kinetics and short-term plasticity. EPSCs in low but not middle and high frequency neurons were suppressed by activation of group I and II metabotropic glutamate receptors (mGluR I and II), with similar modulatory strength between the ipsilateral and contralateral inputs. Unilateral hearing deprivation by cochlea removal reduced the excitatory transmission on the deprived dendritic domain of NL. Interestingly, EPSCs evoked at the deprived domain were modulated more strongly by mGluR II than at the counterpart domain that received intact input in low frequency neurons, suggesting anti-homeostatic regulation. This was supported by a stronger expression of mGluR II protein on the deprived neuropils of NL. Under mGluR II modulation, EPSCs on the deprived input show transient synaptic facilitation, forming a striking contrast with normal hearing conditions under which pure synaptic depression is observed. These results demonstrate physiological symmetry and thus balanced bilateral excitatory inputs to NL neurons. The activity-dependent anti-homeostatic plasticity of mGluR modulation constitutes a novel mechanism regulating synaptic transmission in response to sensory input manipulations.
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Affiliation(s)
- Yong Lu
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA.,School of Biomedical Sciences, Kent State University, Kent, OH, 44240, USA
| | - Yuwei Liu
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA
| | - Rebecca J Curry
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA.,School of Biomedical Sciences, Kent State University, Kent, OH, 44240, USA
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35
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Cuntz H. Mixing audio and video in dendrites. J Physiol 2018; 596:553-554. [PMID: 29314037 DOI: 10.1113/jp275566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Hermann Cuntz
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Frankfurt/Main, Germany.,Frankfurt Institute for Advanced Studies (FIAS), Frankfurt/Main, Germany
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36
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Garden DLF, Oostland M, Jelitai M, Rinaldi A, Duguid I, Nolan MF. Inferior Olive HCN1 Channels Coordinate Synaptic Integration and Complex Spike Timing. Cell Rep 2018; 22:1722-1733. [PMID: 29444426 PMCID: PMC5847187 DOI: 10.1016/j.celrep.2018.01.069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 01/03/2018] [Accepted: 01/22/2018] [Indexed: 02/07/2023] Open
Abstract
Cerebellar climbing-fiber-mediated complex spikes originate from neurons in the inferior olive (IO), are critical for motor coordination, and are central to theories of cerebellar learning. Hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels expressed by IO neurons have been considered as pacemaker currents important for oscillatory and resonant dynamics. Here, we demonstrate that in vitro, network actions of HCN1 channels enable bidirectional glutamatergic synaptic responses, while local actions of HCN1 channels determine the timing and waveform of synaptically driven action potentials. These roles are distinct from, and may complement, proposed pacemaker functions of HCN channels. We find that in behaving animals HCN1 channels reduce variability in the timing of cerebellar complex spikes, which serve as a readout of IO spiking. Our results suggest that spatially distributed actions of HCN1 channels enable the IO to implement network-wide rules for synaptic integration that modulate the timing of cerebellar climbing fiber signals. HCN1 channels in IO neurons control synaptic response and spiking activity Network actions of HCN1 channels enable bidirectional synaptic responses Local actions of HCN1 channels control spike timing and spikelet number In awake mice, HCN1 channels reduce timing variability of cerebellar complex spikes
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Affiliation(s)
- Derek L F Garden
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Marlies Oostland
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Marta Jelitai
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Arianna Rinaldi
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Ian Duguid
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK; Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Matthew F Nolan
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK; Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, UK.
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37
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Bohannon AS, Hablitz JJ. Developmental Changes in HCN Channel Modulation of Neocortical Layer 1 Interneurons. Front Cell Neurosci 2018; 12:20. [PMID: 29440994 PMCID: PMC5797556 DOI: 10.3389/fncel.2018.00020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 01/15/2018] [Indexed: 01/31/2023] Open
Abstract
Layer 1 (L1) interneurons (INs) play a key role in modulating the integration of inputs to pyramidal neurons (PNs) and controlling cortical network activity. Hyperpolarization-activated, cyclic nucleotide-gated, non-specific cation (HCN) channels are known to alter the intrinsic and synaptic excitability of principal components (PCs) as well as select populations of GABAergic INs. However, the developmental profile and functional role of HCN channels in diverse L1 IN populations is not completely understood. In the present study, we used electrophysiological characterization, in conjunction with unbiased hierarchical cluster analysis, to examine developmental modulation of L1 INs by HCN channels in the rat medial agranular cortex (AGm). We identified three physiologically discrete IN populations which were classified as regular spiking (RS), burst accommodating (BA) and non-accommodating (NA). A distinct developmental pattern of excitability modulation by HCN channels was observed for each group. RS and NA cells displayed distinct morphologies with modulation of EPSPs increasing in RS cells and decreasing in NA cells across development. The results indicate a possible role of HCN channels in the formation and maintenance of cortical circuits through alteration of the excitability of distinct AGm L1 INs.
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Affiliation(s)
- Andrew S Bohannon
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - John J Hablitz
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, United States
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38
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Athilingam JC, Ben-Shalom R, Keeshen CM, Sohal VS, Bender KJ. Serotonin enhances excitability and gamma frequency temporal integration in mouse prefrontal fast-spiking interneurons. eLife 2017; 6:31991. [PMID: 29206101 PMCID: PMC5746342 DOI: 10.7554/elife.31991] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 12/02/2017] [Indexed: 11/25/2022] Open
Abstract
The medial prefrontal cortex plays a key role in higher order cognitive functions like decision making and social cognition. These complex behaviors emerge from the coordinated firing of prefrontal neurons. Fast-spiking interneurons (FSIs) control the timing of excitatory neuron firing via somatic inhibition and generate gamma (30–100 Hz) oscillations. Therefore, factors that regulate how FSIs respond to gamma-frequency input could affect both prefrontal circuit activity and behavior. Here, we show that serotonin (5HT), which is known to regulate gamma power, acts via 5HT2A receptors to suppress an inward-rectifying potassium conductance in FSIs. This leads to depolarization, increased input resistance, enhanced spiking, and slowed decay of excitatory post-synaptic potentials (EPSPs). Notably, we found that slowed EPSP decay preferentially enhanced temporal summation and firing elicited by gamma frequency inputs. These findings show how changes in passive membrane properties can affect not only neuronal excitability but also the temporal filtering of synaptic inputs.
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Affiliation(s)
- Jegath C Athilingam
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Neurology, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States.,Neuroscience Graduate Program, University of California, San Francisco, San Francisco, United States
| | - Roy Ben-Shalom
- Department of Neurology, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Caroline M Keeshen
- Department of Neurology, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Vikaas S Sohal
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Kevin J Bender
- Department of Neurology, University of California, San Francisco, San Francisco, United States.,Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, United States.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, United States
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39
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Chen M, Lee S, Zhou ZJ. Local synaptic integration enables ON-OFF asymmetric and layer-specific visual information processing in vGluT3 amacrine cell dendrites. Proc Natl Acad Sci U S A 2017; 114:11518-23. [PMID: 28973895 DOI: 10.1073/pnas.1711622114] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A basic scheme of neuronal organization in the mammalian retina is the segregation of ON and OFF pathways in the inner plexiform layer (IPL), where glutamate is released from ON and OFF bipolar cell terminals in separate inner (ON) and outer (OFF) sublayers in response to light intensity increments and decrements, respectively. However, recent studies have found that vGluT3-expressing glutamatergic amacrine cells (GACs) generate ON-OFF somatic responses and release glutamate onto both ON and OFF ganglion cell types, raising the possibility of crossover excitation in violation of the canonical ON-OFF segregation scheme. To test this possibility, we recorded light-evoked Ca2+ responses from dendrites of individual GACs infected with GCaMP6s in mouse. Under two-photon imaging, a single GAC generated rectified local dendritic responses, showing ON-dominant responses in ON sublayers and OFF-dominant responses in OFF sublayers. This unexpected ON-OFF segregation within a small-field amacrine cell arose from local synaptic processing, mediated predominantly by synaptic inhibition. Multiple forms of synaptic inhibition compartmentalized the GAC dendritic tree and endowed all dendritic varicosities with a small-center, strong-surround receptive field, which varied in receptive field size and degree of ON-OFF asymmetry with IPL depth. The results reveal a form of short-range dendritic autonomy that enables a small-field, dual-transmitter amacrine cell to process diverse dendritic functions in a stratification level- and postsynaptic target-specific manner, while preserving the fundamental ON-OFF segregation scheme for parallel visual processing and high spatial resolution for small object motion and uniformity detection.
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40
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Inada K, Tsuchimoto Y, Kazama H. Origins of Cell-Type-Specific Olfactory Processing in the Drosophila Mushroom Body Circuit. Neuron 2017; 95:357-367.e4. [PMID: 28728024 DOI: 10.1016/j.neuron.2017.06.039] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 05/23/2017] [Accepted: 06/23/2017] [Indexed: 11/23/2022]
Abstract
How cell-type-specific physiological properties shape neuronal functions in a circuit remains poorly understood. We addressed this issue in the Drosophila mushroom body (MB), a higher olfactory circuit, where neurons belonging to distinct glomeruli in the antennal lobe feed excitation to three types of intrinsic neurons, α/β, α'/β', and γ Kenyon cells (KCs). Two-photon optogenetics and intracellular recording revealed that whereas glomerular inputs add similarly in all KCs, spikes were generated most readily in α'/β' KCs. This cell type was also the most competent in recruiting GABAergic inhibition fed back by anterior paired lateral neuron, which responded to odors either locally within a lobe or globally across all lobes depending on the strength of stimuli. Notably, as predicted from these physiological properties, α'/β' KCs had the highest odor detection speed, sensitivity, and discriminability. This enhanced discrimination required proper GABAergic inhibition. These results link cell-type-specific mechanisms and functions in the MB circuit.
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Du K, Wu YW, Lindroos R, Liu Y, Rózsa B, Katona G, Ding JB, Kotaleski JH. Cell-type-specific inhibition of the dendritic plateau potential in striatal spiny projection neurons. Proc Natl Acad Sci U S A 2017; 114:E7612-21. [PMID: 28827326 DOI: 10.1073/pnas.1704893114] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Striatal spiny projection neurons (SPNs) receive convergent excitatory synaptic inputs from the cortex and thalamus. Activation of spatially clustered and temporally synchronized excitatory inputs at the distal dendrites could trigger plateau potentials in SPNs. Such supralinear synaptic integration is crucial for dendritic computation. However, how plateau potentials interact with subsequent excitatory and inhibitory synaptic inputs remains unknown. By combining computational simulation, two-photon imaging, optogenetics, and dual-color uncaging of glutamate and GABA, we demonstrate that plateau potentials can broaden the spatiotemporal window for integrating excitatory inputs and promote spiking. The temporal window of spiking can be delicately controlled by GABAergic inhibition in a cell-type-specific manner. This subtle inhibitory control of plateau potential depends on the location and kinetics of the GABAergic inputs and is achieved by the balance between relief and reestablishment of NMDA receptor Mg2+ block. These findings represent a mechanism for controlling spatiotemporal synaptic integration in SPNs.
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Albertson AJ, Bohannon AS, Hablitz JJ. HCN Channel Modulation of Synaptic Integration in GABAergic Interneurons in Malformed Rat Neocortex. Front Cell Neurosci 2017; 11:109. [PMID: 28469560 PMCID: PMC5396479 DOI: 10.3389/fncel.2017.00109] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 03/30/2017] [Indexed: 12/02/2022] Open
Abstract
Cortical malformations are often associated with pharmaco-resistant epilepsy. Alterations in hyperpolarization-activated, cyclic nucleotide-gated, non-specific cation (HCN) channels have been shown to contribute to malformation associated hyperexcitability. We have recently demonstrated that expression of HCN channels and Ih current amplitudes are reduced in layer (L) 5 pyramidal neurons of rats with freeze lesion induced malformations. These changes were associated with an increased EPSP temporal summation. Here, we examine the effects of HCN channel inhibition on synaptic responses in fast spiking, presumptive basket cells and accommodating, presumptive Martinotti, GABAergic interneurons in slices from freeze lesioned animals. In control animals, fast spiking cells showed small sag responses which were reduced by the HCN channel antagonist ZD7288. Fast spiking cells in lesioned animals showed absent or reduced sag responses. The amplitude of single evoked EPSPs in fast spiking cells in the control group was not affected by HCN channel inhibition with ZD7288. EPSP ratios during short stimulus trains at 25 Hz were not significantly different between control and lesion groups. ZD7288 produced an increase in EPSP ratios in the control but not lesion groups. Under voltage clamp conditions, ZD7288 did not affect EPSC ratios. In the control group, accommodating interneurons showed robust sag responses which were significantly reduced by ZD7288. HCN channel inhibition increased EPSP ratios and area in controls but not the lesioned group. The results indicate that HCN channels differentially modulate EPSPs in different classes of GABAergic interneurons and that this control is reduced in malformed rat neocortex.
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Affiliation(s)
- Asher J Albertson
- Department of Neurobiology, University of Alabama at BirminghamBirmingham, AL, USA
| | - Andrew S Bohannon
- Department of Neurobiology, University of Alabama at BirminghamBirmingham, AL, USA
| | - John J Hablitz
- Department of Neurobiology, University of Alabama at BirminghamBirmingham, AL, USA
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Garden DLF, Rinaldi A, Nolan MF. Active integration of glutamatergic input to the inferior olive generates bidirectional postsynaptic potentials. J Physiol 2016; 595:1239-1251. [PMID: 27767209 PMCID: PMC5309349 DOI: 10.1113/jp273424] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 10/14/2016] [Indexed: 11/15/2022] Open
Abstract
Key points We establish experimental preparations for optogenetic investigation of glutamatergic input to the inferior olive. Neurones in the principal olivary nucleus receive monosynaptic extra‐somatic glutamatergic input from the neocortex. Glutamatergic inputs to neurones in the inferior olive generate bidirectional postsynaptic potentials (PSPs), with a fast excitatory component followed by a slower inhibitory component. Small conductance calcium‐activated potassium (SK) channels are required for the slow inhibitory component of glutamatergic PSPs and oppose temporal summation of inputs at intervals ≤ 20 ms. Active integration of synaptic input within the inferior olive may play a central role in control of olivo‐cerebellar climbing fibre signals.
Abstract The inferior olive plays a critical role in motor coordination and learning by integrating diverse afferent signals to generate climbing fibre inputs to the cerebellar cortex. While it is well established that climbing fibre signals are important for motor coordination, the mechanisms by which neurones in the inferior olive integrate synaptic inputs and the roles of particular ion channels are unclear. Here, we test the hypothesis that neurones in the inferior olive actively integrate glutamatergic synaptic inputs. We demonstrate that optogenetically activated long‐range synaptic inputs to the inferior olive, including projections from the motor cortex, generate rapid excitatory potentials followed by slower inhibitory potentials. Synaptic projections from the motor cortex preferentially target the principal olivary nucleus. We show that inhibitory and excitatory components of the bidirectional synaptic potentials are dependent upon AMPA (GluA) receptors, are GABAA independent, and originate from the same presynaptic axons. Consistent with models that predict active integration of synaptic inputs by inferior olive neurones, we find that the inhibitory component is reduced by blocking large conductance calcium‐activated potassium channels with iberiotoxin, and is abolished by blocking small conductance calcium‐activated potassium channels with apamin. Summation of excitatory components of synaptic responses to inputs at intervals ≤ 20 ms is increased by apamin, suggesting a role for the inhibitory component of glutamatergic responses in temporal integration. Our results indicate that neurones in the inferior olive implement novel rules for synaptic integration and suggest new principles for the contribution of inferior olive neurones to coordinated motor behaviours. We establish experimental preparations for optogenetic investigation of glutamatergic input to the inferior olive. Neurones in the principal olivary nucleus receive monosynaptic extra‐somatic glutamatergic input from the neocortex. Glutamatergic inputs to neurones in the inferior olive generate bidirectional postsynaptic potentials (PSPs), with a fast excitatory component followed by a slower inhibitory component. Small conductance calcium‐activated potassium (SK) channels are required for the slow inhibitory component of glutamatergic PSPs and oppose temporal summation of inputs at intervals ≤ 20 ms. Active integration of synaptic input within the inferior olive may play a central role in control of olivo‐cerebellar climbing fibre signals.
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Affiliation(s)
- Derek L F Garden
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Arianna Rinaldi
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Matthew F Nolan
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK
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Yang S, Santos MD, Tang CM, Kim JG, Yang S. A Postsynaptic Role for Short-Term Neuronal Facilitation in Dendritic Spines. Front Cell Neurosci 2016; 10:224. [PMID: 27746721 PMCID: PMC5043053 DOI: 10.3389/fncel.2016.00224] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Accepted: 09/16/2016] [Indexed: 12/12/2022] Open
Abstract
Synaptic plasticity is a fundamental component of information processing in the brain. Presynaptic facilitation in response to repetitive stimuli, often referred to as paired-pulse facilitation (PPF), is a dominant form of short-term synaptic plasticity. Recently, an additional cellular mechanism for short-term facilitation, short-term postsynaptic plasticity (STPP), has been proposed. While a dendritic mechanism was described in hippocampus, its expression has not yet been demonstrated at the levels of the spine. Furthermore, it is unknown whether the mechanism can be expressed in other brain regions, such as sensory cortex. Here, we demonstrated that a postsynaptic response can be facilitated by prior spine excitation in both hippocampal and cortical neurons, using 3D digital holography and two-photon calcium imaging. The coordinated action of pre- and post-synaptic plasticity may provide a more thorough account of information processing in the brain.
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Affiliation(s)
- Sunggu Yang
- Department of Nano-Bioengineering, Incheon National University Incheon, South Korea
| | - Mariton D Santos
- Department of Neurology and Department of Physiology, University of Maryland School of MedicineBaltimore, MD, USA; Office of Dietary Supplement Programs, Center for Food Safety and Applied Nutrition, US Food and Drug AdministrationCollege Park, MD, USA
| | - Cha-Min Tang
- Department of Neurology and Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
| | - Jae Geun Kim
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University Incheon, South Korea
| | - Sungchil Yang
- Department of Biomedical Sciences, City University of Hong Kong Kowloon, Hong Kong
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Sun W, Matthews EA, Nicolas V, Schoch S, Dietrich D. NG2 glial cells integrate synaptic input in global and dendritic calcium signals. eLife 2016; 5. [PMID: 27644104 PMCID: PMC5052029 DOI: 10.7554/elife.16262] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 09/17/2016] [Indexed: 12/30/2022] Open
Abstract
Synaptic signaling to NG2-expressing oligodendrocyte precursor cells (NG2 cells) could be key to rendering myelination of axons dependent on neuronal activity, but it has remained unclear whether NG2 glial cells integrate and respond to synaptic input. Here we show that NG2 cells perform linear integration of glutamatergic synaptic inputs and respond with increasing dendritic calcium elevations. Synaptic activity induces rapid Ca2+ signals mediated by low-voltage activated Ca2+ channels under strict inhibitory control of voltage-gated A-type K+ channels. Ca2+ signals can be global and originate throughout the cell. However, voltage-gated channels are also found in thin dendrites which act as compartmentalized processing units and generate local calcium transients. Taken together, the activity-dependent control of Ca2+ signals by A-type channels and the global versus local signaling domains make intracellular Ca2+ in NG2 cells a prime signaling molecule to transform neurotransmitter release into activity-dependent myelination. DOI:http://dx.doi.org/10.7554/eLife.16262.001
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Affiliation(s)
- Wenjing Sun
- Department of Neurosurgery, University Clinic Bonn, Bonn, Germany
| | | | - Vicky Nicolas
- Department of Neurosurgery, University Clinic Bonn, Bonn, Germany
| | - Susanne Schoch
- Department of Neuropathology, University Clinic Bonn, Bonn, Germany
| | - Dirk Dietrich
- Department of Neurosurgery, University Clinic Bonn, Bonn, Germany
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Somogyi A, Katonai Z, Alpár A, Wolf E. A Novel Form of Compensation in the Tg2576 Amyloid Mouse Model of Alzheimer's Disease. Front Cell Neurosci 2016; 10:152. [PMID: 27378850 PMCID: PMC4909742 DOI: 10.3389/fncel.2016.00152] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 05/27/2016] [Indexed: 12/02/2022] Open
Abstract
One century after its first description, pathology of Alzheimer’s disease (AD) is still poorly understood. Amyloid-related dendritic atrophy and membrane alterations of susceptible brain neurons in AD, and in animal models of AD are widely recognized. However, little effort has been made to study the potential effects of combined morphological and membrane alterations on signal transfer and synaptic integration in neurons that build up affected neural networks in AD. In this study spatial reconstructions and electrophysiological measurements of layer II/III pyramidal neurons of the somatosensory cortex from wild-type (WT) and transgenic (TG) human amyloid precursor protein (hAPP) overexpressing Tg2576 mice were used to build faithful segmental cable models of these neurons. Local synaptic activities were simulated in various points of the dendritic arbors and properties of subthreshold dendritic impulse propagation and predictors of synaptic input pattern recognition ability were quantified and compared in modeled WT and TG neurons. Despite the widespread dendritic degeneration and membrane alterations in mutant mouse neurons, surprisingly little, or no change was detected in steady-state and 50 Hz sinusoidal voltage transfers, current transfers, and local and propagation delays of PSPs traveling along dendrites of TG neurons. Synaptic input pattern recognition ability was also predicted to be unaltered in TG neurons in two different soma-dendritic membrane models investigated. Our simulations predict the way how subthreshold dendritic signaling and pattern recognition are preserved in TG neurons: amyloid-related membrane alterations compensate for the pathological effects that dendritic atrophy has on subthreshold dendritic signal transfer and integration in layer II/III somatosensory neurons of this hAPP mouse model for AD. Since neither propagation of single PSPs nor integration of multiple PSPs (pattern recognition) changes in TG neurons, we conclude that AD-related neuronal hyperexcitability cannot be accounted for by altered subthreshold dendritic signaling in these neurons but hyperexcitability is related to changes in active membrane properties and network connectivity.
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Affiliation(s)
- Attila Somogyi
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of DebrecenDebrecen, Hungary; Kenézy Gyula Hospital Ltd., Department of Emergency MedicineDebrecen, Hungary
| | - Zoltán Katonai
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen Debrecen, Hungary
| | - Alán Alpár
- MTA-SE NAP B Research Group of Experimental Neuroanatomy and Developmental Biology, Hungarian Academy of SciencesBudapest, Hungary; Department of Anatomy, Semmelweis UniversityBudapest, Hungary
| | - Ervin Wolf
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen Debrecen, Hungary
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Howard MA, Baraban SC. Synaptic integration of transplanted interneuron progenitor cells into native cortical networks. J Neurophysiol 2016; 116:472-8. [PMID: 27226453 DOI: 10.1152/jn.00321.2016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 05/23/2016] [Indexed: 01/22/2023] Open
Abstract
Interneuron-based cell transplantation is a powerful method to modify network function in a variety of neurological disorders, including epilepsy. Whether new interneurons integrate into native neural networks in a subtype-specific manner is not well understood, and the therapeutic mechanisms underlying interneuron-based cell therapy, including the role of synaptic inhibition, are debated. In this study, we tested subtype-specific integration of transplanted interneurons using acute cortical brain slices and visualized patch-clamp recordings to measure excitatory synaptic inputs, intrinsic properties, and inhibitory synaptic outputs. Fluorescently labeled progenitor cells from the embryonic medial ganglionic eminence (MGE) were used for transplantation. At 5 wk after transplantation, MGE-derived parvalbumin-positive (PV+) interneurons received excitatory synaptic inputs, exhibited mature interneuron firing properties, and made functional synaptic inhibitory connections to native pyramidal cells that were comparable to those of native PV+ interneurons. These findings demonstrate that MGE-derived PV+ interneurons functionally integrate into subtype-appropriate physiological niches within host networks following transplantation.
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Affiliation(s)
- MacKenzie A Howard
- Epilepsy Research Laboratory in the Department of Neurological Surgery, University of California, San Francisco, California
| | - Scott C Baraban
- Epilepsy Research Laboratory in the Department of Neurological Surgery, University of California, San Francisco, California
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Acker CD, Hoyos E, Loew LM. EPSPs Measured in Proximal Dendritic Spines of Cortical Pyramidal Neurons. eNeuro 2016; 3:ENEURO. [PMID: 27257618 DOI: 10.1523/ENEURO.0050-15.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 04/22/2016] [Accepted: 04/24/2016] [Indexed: 12/16/2022] Open
Abstract
EPSPs occur when the neurotransmitter glutamate binds to postsynaptic receptors located on small pleomorphic membrane protrusions called dendritic spines. To transmit the synaptic signal, these potentials must travel through the spine neck and the dendritic tree to reach the soma. Due to their small size, the electrical behavior of spines and their ability to compartmentalize electrical signals has been very difficult to assess experimentally. In this study, we developed a method to perform simultaneous two-photon voltage-sensitive dye recording with two-photon glutamate uncaging in order to measure the characteristics (amplitude and duration) of uncaging-evoked EPSPs in single spines on the basal dendrites of L5 pyramidal neurons in acute brain slices from CD1 control mice. We were able to record uncaging-evoked spine potentials that resembled miniature EPSPs at the soma from a wide range of spine morphologies. In proximal spines, these potentials averaged 13.0 mV (range, 6.5–30.8 mV; N = 20) for an average somatic EPSP of 0.59 mV, whereas the mean attenuation ratio (spine/soma) was found to be 25.3. Durations of spine EPSP waveforms were found to be 11.7 ms on average. Modeling studies demonstrate the important role that spine neck resistance (Rneck) plays in spine EPSP amplitudes. Simulations used to estimate Rneck by fits to voltage-sensitive dye measurements produced a mean of 179 MΩ (range, 23–420 MΩ; N = 19). Independent measurements based on fluorescence recovery after photobleaching of a cytosolic dye from spines of the same population of neurons produced a mean Rneck estimate of 204 MΩ (range, 52–521 MΩ; N = 34).
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Kullmann PHM, Sikora KM, Clark KL, Arduini I, Springer MG, Horn JP. HCN hyperpolarization-activated cation channels strengthen virtual nicotinic EPSPs and thereby elevate synaptic amplification in rat sympathetic neurons. J Neurophysiol 2016; 116:438-47. [PMID: 27146984 DOI: 10.1152/jn.00223.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 05/02/2016] [Indexed: 12/27/2022] Open
Abstract
The influence of hyperpolarization-activated cation current (h-current; Ih) upon synaptic integration in paravertebral sympathetic neurons was studied together with expression of hyperpolarization-activated cyclic nucleotide-gated (HCN) subunit isoforms. All four HCN subunits were detected in homogenates of the rat superior cervical ganglion (SCG) using the PCR to amplify reverse-transcribed messenger RNAs (RT-PCR) and using quantitative PCR. Voltage clamp recordings from dissociated SCG neurons at 35°C detected Ih in all cells, with a maximum hyperpolarization-activated cation conductance of 1.2 ± 0.1 nS, half-maximal activation at -87.6 mV, and reversal potential of -31.6 mV. Interaction between Ih and synaptic potentials was tested with virtual fast nicotinic excitatory postsynaptic potentials (EPSPs) created with dynamic clamp. The blocking of Ih with 15 μM ZD7288 hyperpolarized cells by 4.7 mV and increased the virtual synaptic conductance required to stimulate an action potential from 7.0 ± 0.9 nS to 12.1 ± 0.9 nS. In response to stimulation with 40 s long trains of virtual EPSPs, ZD7288 reduced postsynaptic firing from 2.2 to 1.7 Hz and the associated synaptic amplification from 2.2 ± 0.1 to 1.7 ± 0.2. Cyclic nucleotide binding to HCN channels was simulated by blocking native Ih with ZD7288, followed by reconstitution with virtual Ih using a dynamic clamp model of the voltage clamp data. Over a 30-mV range, shifting the half-activation voltage for Ih in 10 mV depolarizing increments always increased synaptic gain. These results indicate that Ih, in sympathetic neurons, can strengthen nicotinic EPSPs and increase synaptic amplification, while also working as a substrate for cyclic nucleotide-dependent modulation.
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Affiliation(s)
- Paul H M Kullmann
- Department of Neurobiology and Center for Neuroscience, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Kristine M Sikora
- Department of Neurobiology and Center for Neuroscience, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - K Lyles Clark
- Department of Neurobiology and Center for Neuroscience, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Irene Arduini
- Department of Neurobiology and Center for Neuroscience, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Mitchell G Springer
- Department of Neurobiology and Center for Neuroscience, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - John P Horn
- Department of Neurobiology and Center for Neuroscience, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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Royeck M, Kelly T, Opitz T, Otte DM, Rennhack A, Woitecki A, Pitsch J, Becker A, Schoch S, Kaupp UB, Yaari Y, Zimmer A, Beck H. Downregulation of Spermine Augments Dendritic Persistent Sodium Currents and Synaptic Integration after Status Epilepticus. J Neurosci 2015; 35:15240-53. [PMID: 26586813 DOI: 10.1523/JNEUROSCI.0493-15.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Dendritic voltage-gated ion channels profoundly shape the integrative properties of neuronal dendrites. In epilepsy, numerous changes in dendritic ion channels have been described, all of them due to either their altered transcription or phosphorylation. In pilocarpine-treated chronically epileptic rats, we describe a novel mechanism that causes an increased proximal dendritic persistent Na(+) current (INaP). We demonstrate using a combination of electrophysiology and molecular approaches that the upregulation of dendritic INaP is due to a relief from polyamine-dependent inhibition. The polyamine deficit in hippocampal neurons is likely caused by an upregulation of the degrading enzyme spermidine/spermine acetyltransferase. Multiphoton glutamate uncaging experiments revealed that the increase in dendritic INaP causes augmented dendritic summation of excitatory inputs. These results establish a novel post-transcriptional modification of ion channels in chronic epilepsy and may provide a novel avenue for treatment of temporal lobe epilepsy. SIGNIFICANCE STATEMENT In this paper, we describe a novel mechanism that causes increased dendritic persistent Na(+) current. We demonstrate using a combination of electrophysiology and molecular approaches that the upregulation of persistent Na(+) currents is due to a relief from polyamine-dependent inhibition. The polyamine deficit in hippocampal neurons is likely caused by an upregulation of the degrading enzyme spermidine/spermine acetyltransferase. Multiphoton glutamate uncaging experiments revealed that the increase in dendritic persistent Na current causes augmented dendritic summation of excitatory inputs. We believe that these results establish a novel post-transcriptional modification of ion channels in chronic epilepsy.
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