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Williams SR, Zhou X, Fletcher LN. Compartment-specific dendritic information processing in striatal cholinergic interneurons is reconfigured by peptide neuromodulation. Neuron 2023; 111:1933-1951.e3. [PMID: 37086722 DOI: 10.1016/j.neuron.2023.03.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 03/29/2023] [Accepted: 03/30/2023] [Indexed: 04/24/2023]
Abstract
Cholinergic interneurons are central hubs of the striatal neuronal network, controlling information processing in a behavioral-state-dependent manner. It remains unknown, however, how such state transitions influence the integrative properties of these neurons. To address this, we made simultaneous somato-dendritic recordings from identified rodent cholinergic interneurons, revealing that action potentials are initiated at dendritic sites because of a dendritic axonal origin. Functionally, this anatomical arrangement ensured that the action potential initiation threshold was lowest at axon-bearing dendritic sites, a privilege efficacy powerfully accentuated at the hyperpolarized membrane potentials achieved in cholinergic interneurons following salient behavioral stimuli. Experimental analysis revealed the voltage-dependent attenuation of the efficacy of non-axon-bearing dendritic excitatory input was mediated by the recruitment of dendritic potassium channels, a regulatory mechanism that, in turn, was controlled by the pharmacological activation of neurokinin receptors. Together, these results indicate that the neuropeptide microenvironment dynamically controls state- and compartment-dependent dendritic information processing in striatal cholinergic interneurons.
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Affiliation(s)
- Stephen R Williams
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD 4072, Australia.
| | - Xiangyu Zhou
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Lee Norman Fletcher
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD 4072, Australia.
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2
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Reconstruction of sparse recurrent connectivity and inputs from the nonlinear dynamics of neuronal networks. J Comput Neurosci 2023; 51:43-58. [PMID: 35849304 DOI: 10.1007/s10827-022-00831-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/16/2022] [Accepted: 07/13/2022] [Indexed: 01/18/2023]
Abstract
Reconstructing the recurrent structural connectivity of neuronal networks is a challenge crucial to address in characterizing neuronal computations. While directly measuring the detailed connectivity structure is generally prohibitive for large networks, we develop a novel framework for reverse-engineering large-scale recurrent network connectivity matrices from neuronal dynamics by utilizing the widespread sparsity of neuronal connections. We derive a linear input-output mapping that underlies the irregular dynamics of a model network composed of both excitatory and inhibitory integrate-and-fire neurons with pulse coupling, thereby relating network inputs to evoked neuronal activity. Using this embedded mapping and experimentally feasible measurements of the firing rate as well as voltage dynamics in response to a relatively small ensemble of random input stimuli, we efficiently reconstruct the recurrent network connectivity via compressive sensing techniques. Through analogous analysis, we then recover high dimensional natural stimuli from evoked neuronal network dynamics over a short time horizon. This work provides a generalizable methodology for rapidly recovering sparse neuronal network data and underlines the natural role of sparsity in facilitating the efficient encoding of network data in neuronal dynamics.
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3
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Li S, Wu L, Zhu M, Cheng X, Jiang X. Effect of dipole potential on the orientation of Voltage-gated Alamethicin peptides regulated by chaotropic anions. J Electroanal Chem (Lausanne) 2022. [DOI: 10.1016/j.jelechem.2021.115880] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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4
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Lehnhoff J, Strauss U, Wierschke S, Grosser S, Pollali E, Schneider UC, Holtkamp M, Dehnicke C, Deisz RA. The anticonvulsant lamotrigine enhances Ih in layer 2/3 neocortical pyramidal neurons of patients with pharmacoresistant epilepsy. Neuropharmacology 2019; 144:58-69. [DOI: 10.1016/j.neuropharm.2018.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 09/19/2018] [Accepted: 10/05/2018] [Indexed: 11/29/2022]
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5
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Zhu N, Huang W, Hu X, Liu Y, Fang Z, Guo K. Enzymatic Continuous Flow Synthesis of Thiol-Terminated Poly(δ-Valerolactone) and Block Copolymers. Macromol Rapid Commun 2018; 39:e1700807. [PMID: 29450925 DOI: 10.1002/marc.201700807] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/10/2018] [Indexed: 11/08/2022]
Abstract
Thiol-terminated poly(δ-valerolactone) is directly synthesized via enzymatic 6-mercapto-1-hexanol initiated ring-opening polymerization in both batch and microreactor. By using Candida antartica Lipase B immobilized tubular reactor, narrowly dispersed poly(δ-valerolactone) with higher thiol fidelity is more efficiently prepared in contrast to the batch reactor. Moreover, the integrated enzyme packed tubular reactor system is established to perform the chain extension experiments. Thiol-terminated poly(δ-valerolactone)-block-poly(ε-caprolactone) and poly(ε-caprolactone)-block-poly(δ-valerolactone) are easily prepared by modulating the monomer introduction sequence.
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Affiliation(s)
- Ning Zhu
- College of Biotechnology and Pharmaceutical Engineering, Jiangsu National Synergetic Innovation Centre for Advanced Materials, Nanjing Tech University, Nanjing, 211800, China
| | - Weijun Huang
- College of Biotechnology and Pharmaceutical Engineering, Jiangsu National Synergetic Innovation Centre for Advanced Materials, Nanjing Tech University, Nanjing, 211800, China
| | - Xin Hu
- College of Materials Science and Engineering, Jiangsu National Synergetic Innovation Centre for Advanced Materials, Nanjing Tech University, Nanjing, 211800, China
| | - Yihuan Liu
- College of Biotechnology and Pharmaceutical Engineering, Jiangsu National Synergetic Innovation Centre for Advanced Materials, Nanjing Tech University, Nanjing, 211800, China
| | - Zheng Fang
- College of Biotechnology and Pharmaceutical Engineering, Jiangsu National Synergetic Innovation Centre for Advanced Materials, Nanjing Tech University, Nanjing, 211800, China
| | - Kai Guo
- College of Biotechnology and Pharmaceutical Engineering, State Key Laboratory of Materials-Oriented Chemical Engineering, Jiangsu National Synergetic Innovation Centre for Advanced Materials, Nanjing Tech University, Nanjing, 211800, China
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6
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Mangold KE, Brumback BD, Angsutararux P, Voelker TL, Zhu W, Kang PW, Moreno JD, Silva JR. Mechanisms and models of cardiac sodium channel inactivation. Channels (Austin) 2017; 11:517-533. [PMID: 28837385 PMCID: PMC5786193 DOI: 10.1080/19336950.2017.1369637] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 08/14/2017] [Accepted: 08/15/2017] [Indexed: 12/19/2022] Open
Abstract
Shortly after cardiac Na+ channels activate and initiate the action potential, inactivation ensues within milliseconds, attenuating the peak Na+ current, INa, and allowing the cell membrane to repolarize. A very limited number of Na+ channels that do not inactivate carry a persistent INa, or late INa. While late INa is only a small fraction of peak magnitude, it significantly prolongs ventricular action potential duration, which predisposes patients to arrhythmia. Here, we review our current understanding of inactivation mechanisms, their regulation, and how they have been modeled computationally. Based on this body of work, we conclude that inactivation and its connection to late INa would be best modeled with a "feet-on-the-door" approach where multiple channel components participate in determining inactivation and late INa. This model reflects experimental findings showing that perturbation of many channel locations can destabilize inactivation and cause pathological late INa.
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Affiliation(s)
- Kathryn E. Mangold
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Brittany D. Brumback
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Paweorn Angsutararux
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Taylor L. Voelker
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Wandi Zhu
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Po Wei Kang
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Jonathan D. Moreno
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Jonathan R. Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
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7
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Li L, Sun H, Ding J, Niu C, Su M, Zhang L, Li Y, Wang C, Gamper N, Du X, Zhang H. Selective targeting of M-type potassium K v 7.4 channels demonstrates their key role in the regulation of dopaminergic neuronal excitability and depression-like behaviour. Br J Pharmacol 2017; 174:4277-4294. [PMID: 28885682 DOI: 10.1111/bph.14026] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 08/20/2017] [Accepted: 08/21/2017] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND AND PURPOSE The mesolimbic dopamine system originating in the ventral tegmental area (VTA) is involved in the development of depression, and firing patterns of VTA dopaminergic neurons are key determinants in this process. Here, we describe a crucial role for the M-type Kv 7.4 channels in modulating excitability of VTA dopaminergic neurons and in the development of depressive behaviour in mice. EXPERIMENTAL APPROACH We used Kv 7.4 channel knockout mice and a social defeat model of depression in combination with electrophysiological techniques (patch clamp recording and in vivo single-unit recordings), immunohistochemistry, single-cell PCR and behavioural analyses (social interaction time and glucose preference tests) to investigate VTA circuits involved in the development of depression-like behaviour. KEY RESULTS Among the Kv 7 channels, Kv 7.4 channels are selectively expressed in dopaminergic neurons of the VTA. Using a newly identified selective Kv 7.4 channel activator, fasudil, and Kv 7.4 channel knockout mice, we demonstrate that these channels are a dominant modulator of excitability of VTA dopaminergic neurons, in vitro and in vivo. Down-regulation of Kv 7.4 channels could be a causal factor of the altered excitability of VTA dopaminergic neurons and depression-like behaviour. The selective Kv 7.4 channel activator, fasudil, strongly alleviated depression-like behaviour in the social defeat mouse model of depression. CONCLUSION AND IMPLICATIONS Because expression of Kv 7.4 channels in the CNS is limited, selectively targeting this M channel subunit is likely to produce less on-target side effects than non-selective M channel modulators. Thus, Kv 7.4 channels may offer alternative targets in treatment of depression.
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Affiliation(s)
- Li Li
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Hui Sun
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Jie Ding
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Chenxu Niu
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Min Su
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Ludi Zhang
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Yingmin Li
- Department of Forensic Medicine, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Chuan Wang
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Nikita Gamper
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China.,Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Xiaona Du
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Hailin Zhang
- Department of Pharmacology; The Key Laboratory of Neural and Vascular Biology, Ministry of Education; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
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8
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Shah MM. Recording Hyperpolarization-Activated Cyclic Nucleotide-Gated Channel Currents (Ih) in Neurons. Cold Spring Harb Protoc 2016; 2016:2016/7/pdb.prot091462. [PMID: 27371600 DOI: 10.1101/pdb.prot091462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are voltage-gated ion channels that play a crucial role in many physiological processes such as memory formation and spatial navigation. Alterations in expression and function of HCN channels have also been associated with multiple disorders including epilepsy, neuropathic pain, and anxiety/depression. Interestingly, neuronal HCN currents (Ih) have diverse biophysical properties in different neurons. This is likely to be in part caused by the heterogeneity of the HCN subunits expressed in neurons. This variation in biophysical characteristics is likely to influence how Ih affects neuronal activity. Thus, it is important to record Ih directly from individual neurons. This protocol describes voltage-clamp methods that can be used to record neuronal Ih under whole-cell voltage-clamp conditions, in cell-attached mode, or with outside-out patches. The information obtained using this approach can be used in combination with other techniques such as computational modeling to determine the significance of Ih for neuronal function.
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Affiliation(s)
- Mala M Shah
- Department of Pharmacology, UCL School of Pharmacy, University College London, London, WC1N 1AX, United Kingdom
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9
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Rowan MJM, DelCanto G, Yu JJ, Kamasawa N, Christie JM. Synapse-Level Determination of Action Potential Duration by K(+) Channel Clustering in Axons. Neuron 2016; 91:370-83. [PMID: 27346528 DOI: 10.1016/j.neuron.2016.05.035] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 03/13/2016] [Accepted: 05/23/2016] [Indexed: 10/21/2022]
Abstract
In axons, an action potential (AP) is thought to be broadcast as an unwavering binary pulse over its arbor, driving neurotransmission uniformly at release sites. Yet by recording from axons of cerebellar stellate cell (SC) interneurons, we show that AP width varies between presynaptic bouton sites, even within the same axon branch. The varicose geometry of SC boutons alone does not impose differences in spike duration. Rather, axonal patching revealed heterogeneous peak conductance densities of currents mediated mainly by fast-activating Kv3-type potassium channels, with clustered hotspots at boutons and restricted expression at adjoining shafts. Blockade of Kv channels at individual boutons indicates that currents immediately local to a release site direct spike repolarization at that location. Thus, the clustered arrangement and variable expression density of Kv3 channels at boutons are key determinants underlying compartmentalized control of AP width in a near synapse-by-synapse manner, multiplying the signaling capacity of these structures.
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Affiliation(s)
- Matthew J M Rowan
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Gina DelCanto
- Wilkes Honors Campus of Florida Atlantic University, Jupiter, FL 33405, USA
| | - Jianqing J Yu
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Naomi Kamasawa
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA
| | - Jason M Christie
- Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA.
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10
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Williams AD, Jung S, Poolos NP. Protein kinase C bidirectionally modulates Ih and hyperpolarization-activated cyclic nucleotide-gated (HCN) channel surface expression in hippocampal pyramidal neurons. J Physiol 2015; 593:2779-92. [PMID: 25820761 PMCID: PMC4506181 DOI: 10.1113/jp270453] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 03/25/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, particularly that of the HCN1 isoform, are enriched in the distal dendrites of hippocampal CA1 pyramidal neurons; these channels have physiological functions with respect to decreasing neuronal excitability. In the present study, we aimed to investigate phosphorylation as a mechanism controlling Ih amplitude and HCN1 surface expression in hippocampal principal neurons under normal physiological conditions. Tyrosine phosphorylation decreased Ih amplitude at maximal activation (maximal Ih ), without altering HCN1 surface expression, in two classes of hippocampal principal neurons. Inhibition of serine/threonine protein phosphatases 1 and 2A decreased maximal Ih and HCN1 surface expression in hippocampal principal neurons. Protein kinase C (PKC) activation irreversibly diminished Ih and HCN1 surface expression, whereas PKC inhibition augmented Ih and HCN1 surface expression. PKC activation increased HCN1 channel phosphorylation. These results demonstrate the novel finding of a phosphorylation mechanism, dependent on PKC activity, which bidirectionally modulates Ih amplitude and HCN1channel surface expression in hippocampal principal neurons under normal physiological conditions. ABSTRACT Hyperpolarization-activated, cyclic nucleotide-gated (HCN) ion channels attenuate excitability in hippocampal pyramidal neurons. Loss of HCN channel-mediated current (Ih ), particularly that mediated by the HCN1 isoform, occurs with the development of epilepsy. Previously, we showed that, following pilocarpine-induced status epilepticus, there are two independent changes in HCN function in dendrites: decreased Ih amplitude associated with a loss of HCN1 surface expression and a hyperpolarizing shift in voltage-dependence of activation (gating). The hyperpolarizing shift in gating was attributed to decreased phosphorylation as a result of a loss of p38 mitogen-activated protein kinase activity and increased calcineurin activity; however, the mechanisms controlling Ih amplitude and HCN1 surface expression under epileptic or normal physiological conditions are poorly understood. We aimed to investigate phosphorylation as a mechanism regulating Ih amplitude and HCN1 surface expression (i.e. as is the case for HCN gating) in hippocampal principal neurons under normal physiological conditions. We discovered that inhibition of either tyrosine phosphatases or the serine/threonine protein phosphatases 1 and 2A decreased Ih at maximal activation in hippocampal CA1 pyramidal dendrites and pyramidal-like principal neuron somata from naïve rats. Furthermore, we found that inhibition of PP1/PP2A decreased HCN1 surface expression, whereas tyrosine phosphatase inhibition did not. Protein kinase C (PKC) activation reduced Ih amplitude and HCN1 surface expression, whereas PKC inhibition produced the opposite effect. Inhibition of protein phosphatases 1 and 2A and activation of PKC increased the serine phosphorylation state of the HCN1 protein. The effect of PKC activation on Ih was irreversible. These results indicate that PKC bidirectionally modulates Ih amplitude and HCN1 surface expression in hippocampal principal neurons.
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Affiliation(s)
- Aaron D Williams
- Department of Physiology and Biophysics, University of Washington
| | - Sangwook Jung
- Department of Physiology and Biophysics, University of Washington
| | - Nicholas P Poolos
- Department of Physiology and Biophysics, University of Washington
- Department of Neurology and Regional Epilepsy Center, University of Washington, Seattle, WA, USA
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Ramaswamy S, Markram H. Anatomy and physiology of the thick-tufted layer 5 pyramidal neuron. Front Cell Neurosci 2015; 9:233. [PMID: 26167146 PMCID: PMC4481152 DOI: 10.3389/fncel.2015.00233] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 06/08/2015] [Indexed: 11/13/2022] Open
Abstract
The thick-tufted layer 5 (TTL5) pyramidal neuron is one of the most extensively studied neuron types in the mammalian neocortex and has become a benchmark for understanding information processing in excitatory neurons. By virtue of having the widest local axonal and dendritic arborization, the TTL5 neuron encompasses various local neocortical neurons and thereby defines the dimensions of neocortical microcircuitry. The TTL5 neuron integrates input across all neocortical layers and is the principal output pathway funneling information flow to subcortical structures. Several studies over the past decades have investigated the anatomy, physiology, synaptology, and pathophysiology of the TTL5 neuron. This review summarizes key discoveries and identifies potential avenues of research to facilitate an integrated and unifying understanding on the role of a central neuron in the neocortex.
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Affiliation(s)
- Srikanth Ramaswamy
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Campus Biotech Geneva, Switzerland
| | - Henry Markram
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Campus Biotech Geneva, Switzerland
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12
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Distribution and function of HCN channels in the apical dendritic tuft of neocortical pyramidal neurons. J Neurosci 2015; 35:1024-37. [PMID: 25609619 DOI: 10.1523/jneurosci.2813-14.2015] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The apical tuft is the most remote area of the dendritic tree of neocortical pyramidal neurons. Despite its distal location, the apical dendritic tuft of layer 5 pyramidal neurons receives substantial excitatory synaptic drive and actively processes corticocortical input during behavior. The properties of the voltage-activated ion channels that regulate synaptic integration in tuft dendrites have, however, not been thoroughly investigated. Here, we use electrophysiological and optical approaches to examine the subcellular distribution and function of hyperpolarization-activated cyclic nucleotide-gated nonselective cation (HCN) channels in rat layer 5B pyramidal neurons. Outside-out patch recordings demonstrated that the amplitude and properties of ensemble HCN channel activity were uniform in patches excised from distal apical dendritic trunk and tuft sites. Simultaneous apical dendritic tuft and trunk whole-cell current-clamp recordings revealed that the pharmacological blockade of HCN channels decreased voltage compartmentalization and enhanced the generation and spread of apical dendritic tuft and trunk regenerative activity. Furthermore, multisite two-photon glutamate uncaging demonstrated that HCN channels control the amplitude and duration of synaptically evoked regenerative activity in the distal apical dendritic tuft. In contrast, at proximal apical dendritic trunk and somatic recording sites, the blockade of HCN channels decreased excitability. Dynamic-clamp experiments revealed that these compartment-specific actions of HCN channels were heavily influenced by the local and distributed impact of the high density of HCN channels in the distal apical dendritic arbor. The properties and subcellular distribution pattern of HCN channels are therefore tuned to regulate the interaction between integration compartments in layer 5B pyramidal neurons.
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13
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Fenrich KK, Zhao EY, Wei Y, Garg A, Rose PK. Isolating specific cell and tissue compartments from 3D images for quantitative regional distribution analysis using novel computer algorithms. J Neurosci Methods 2014; 226:42-56. [PMID: 24487018 DOI: 10.1016/j.jneumeth.2014.01.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 01/08/2014] [Accepted: 01/13/2014] [Indexed: 11/30/2022]
Abstract
BACKGROUND Isolating specific cellular and tissue compartments from 3D image stacks for quantitative distribution analysis is crucial for understanding cellular and tissue physiology under normal and pathological conditions. Current approaches are limited because they are designed to map the distributions of synapses onto the dendrites of stained neurons and/or require specific proprietary software packages for their implementation. NEW METHOD To overcome these obstacles, we developed algorithms to Grow and Shrink Volumes of Interest (GSVI) to isolate specific cellular and tissue compartments from 3D image stacks for quantitative analysis and incorporated these algorithms into a user-friendly computer program that is open source and downloadable at no cost. RESULTS The GSVI algorithm was used to isolate perivascular regions in the cortex of live animals and cell membrane regions of stained spinal motoneurons in histological sections. We tracked the real-time, intravital biodistribution of injected fluorophores with sub-cellular resolution from the vascular lumen to the perivascular and parenchymal space following a vascular microlesion, and mapped the precise distributions of membrane-associated KCC2 and gephyrin immunolabeling in dendritic and somatic regions of spinal motoneurons. COMPARISON WITH EXISTING METHODS Compared to existing approaches, the GSVI approach is specifically designed for isolating perivascular regions and membrane-associated regions for quantitative analysis, is user-friendly, and free. CONCLUSIONS The GSVI algorithm is useful to quantify regional differences of stained biomarkers (e.g., cell membrane-associated channels) in relation to cell functions, and the effects of therapeutic strategies on the redistributions of biomolecules, drugs, and cells in diseased or injured tissues.
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Affiliation(s)
- Keith K Fenrich
- CIHR Group in Sensory-Motor Integration, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada K7L 3N6; Center for Neuroscience Studies, Queen's University, Kingston, ON, Canada K7L 3N6; Aix Marseille University, Developmental Biology Institute of Marseille-Luminy (IBDML), CNRS 7288, Case 907 - Parc Scientifique de Luminy, 13009 Marseille, France; Faculty of Rehabilitation Medicine, University of Alberta, 3-88 Corbett Hall, Edmonton, AB, Canada T6G 2G4.
| | - Ethan Y Zhao
- CIHR Group in Sensory-Motor Integration, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada K7L 3N6; Center for Neuroscience Studies, Queen's University, Kingston, ON, Canada K7L 3N6
| | - Yuan Wei
- CIHR Group in Sensory-Motor Integration, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada K7L 3N6; Center for Neuroscience Studies, Queen's University, Kingston, ON, Canada K7L 3N6
| | - Anirudh Garg
- CIHR Group in Sensory-Motor Integration, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada K7L 3N6; Center for Neuroscience Studies, Queen's University, Kingston, ON, Canada K7L 3N6
| | - P Ken Rose
- CIHR Group in Sensory-Motor Integration, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada K7L 3N6; Center for Neuroscience Studies, Queen's University, Kingston, ON, Canada K7L 3N6.
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14
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Battefeld A, Tran BT, Gavrilis J, Cooper EC, Kole MHP. Heteromeric Kv7.2/7.3 channels differentially regulate action potential initiation and conduction in neocortical myelinated axons. J Neurosci 2014; 34:3719-32. [PMID: 24599470 PMCID: PMC3942587 DOI: 10.1523/jneurosci.4206-13.2014] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 01/27/2014] [Accepted: 01/30/2014] [Indexed: 12/14/2022] Open
Abstract
Rapid energy-efficient signaling along vertebrate axons is achieved through intricate subcellular arrangements of voltage-gated ion channels and myelination. One recently appreciated example is the tight colocalization of K(v)7 potassium channels and voltage-gated sodium (Na(v)) channels in the axonal initial segment and nodes of Ranvier. The local biophysical properties of these K(v)7 channels and the functional impact of colocalization with Na(v) channels remain poorly understood. Here, we quantitatively examined K(v)7 channels in myelinated axons of rat neocortical pyramidal neurons using high-resolution confocal imaging and patch-clamp recording. K(v)7.2 and 7.3 immunoreactivity steeply increased within the distal two-thirds of the axon initial segment and was mirrored by the conductance density estimates, which increased from ~12 (proximal) to 150 pS μm(-2) (distal). The axonal initial segment and nodal M-currents were similar in voltage dependence and kinetics, carried by K(v)7.2/7.3 heterotetramers, 4% activated at the resting membrane potential and rapidly activated with single-exponential time constants (~15 ms at 28 mV). Experiments and computational modeling showed that while somatodendritic K(v)7 channels are strongly activated by the backpropagating action potential to attenuate the afterdepolarization and repetitive firing, axonal K(v)7 channels are minimally recruited by the forward-propagating action potential. Instead, in nodal domains K(v)7.2/7.3 channels were found to increase Na(v) channel availability and action potential amplitude by stabilizing the resting membrane potential. Thus, K(v)7 clustering near axonal Na(v) channels serves specific and context-dependent roles, both restraining initiation and enhancing conduction of the action potential.
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Affiliation(s)
- Arne Battefeld
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, 1105 BA, Amsterdam, The Netherlands
| | - Baouyen T. Tran
- Baylor College of Medicine, Baylor Plaza, Houston, Texas 77030
| | - Jason Gavrilis
- Eccles Institute for Neuroscience, The Australian National University, Canberra 0200, Australian Capital Territory, Australia, and
- Department of Audiology and Speech Pathology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | | | - Maarten H. P. Kole
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, 1105 BA, Amsterdam, The Netherlands
- Eccles Institute for Neuroscience, The Australian National University, Canberra 0200, Australian Capital Territory, Australia, and
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15
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Giglio AM, Storm JF. Postnatal development of temporal integration, spike timing and spike threshold regulation by a dendrotoxin-sensitive K+current in rat CA1 hippocampal cells. Eur J Neurosci 2013; 39:12-23. [DOI: 10.1111/ejn.12385] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Revised: 08/30/2013] [Accepted: 09/10/2013] [Indexed: 12/19/2022]
Affiliation(s)
- Anna M. Giglio
- Institute of Basal Medicine; Department of Physiology and Centre of Molecular Biology and Neuroscience; University of Oslo; PB 1104 Blindern, 0317 Oslo Norway
| | - Johan F. Storm
- Institute of Basal Medicine; Department of Physiology and Centre of Molecular Biology and Neuroscience; University of Oslo; PB 1104 Blindern, 0317 Oslo Norway
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16
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Dougherty KA, Nicholson DA, Diaz L, Buss EW, Neuman KM, Chetkovich DM, Johnston D. Differential expression of HCN subunits alters voltage-dependent gating of h-channels in CA1 pyramidal neurons from dorsal and ventral hippocampus. J Neurophysiol 2013; 109:1940-53. [PMID: 23324324 PMCID: PMC3628004 DOI: 10.1152/jn.00010.2013] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 01/12/2013] [Indexed: 12/23/2022] Open
Abstract
The rodent hippocampus can be divided into dorsal (DHC) and ventral (VHC) domains on the basis of behavioral, anatomical, and biochemical differences. Recently, we reported that CA1 pyramidal neurons from the VHC were intrinsically more excitable than DHC neurons, but the specific ionic conductances contributing to this difference were not determined. Here we investigated the hyperpolarization-activated current (I(h)) and the expression of HCN1 and HCN2 channel subunits in CA1 pyramidal neurons from the DHC and VHC. Measurement of Ih with cell-attached patches revealed a significant depolarizing shift in the V(1/2) of activation for dendritic h-channels in VHC neurons (but not DHC neurons), and ultrastructural immunolocalization of HCN1 and HCN2 channels revealed a significantly larger HCN1-to-HCN2 ratio for VHC neurons (but not DHC neurons). These observations suggest that a shift in the expression of HCN1 and HCN2 channels drives functional changes in I(h) for VHC neurons (but not DHC neurons) and could thereby significantly alter the capacity for dendritic integration of these neurons.
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Affiliation(s)
- Kelly A Dougherty
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712, USA.
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17
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Khurana S, Li WK. Baptisms of fire or death knells for acute-slice physiology in the age of ‘omics’ and light? Rev Neurosci 2013; 24:527-36. [DOI: 10.1515/revneuro-2013-0028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Accepted: 08/23/2013] [Indexed: 11/15/2022]
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Abstract
Cell-attached recording is extensively used to study the firing rate of mammalian neurons, but potential limitations of the method have not been investigated in detail. Here we perform cell-attached recording of molecular layer interneurons in cerebellar slices from rats and mice, and we study how experimental conditions influence the measured firing rate. We find that this rate depends on time in cell-attached mode, on pipette potential, and on pipette ionic composition. In the first minute after sealing, action currents are variable in shape and size, presumably reflecting membrane instability. The firing rate remains approximately constant during the first 4 min after sealing and gradually increases afterward. Making the pipette potential more positive leads to an increase in the firing rate, with a steeper dependence on voltage if the pipette solution contains K(+) as the main cation than if it contains Na(+). Ca(2+) imaging experiments show that establishing a cell-attached recording can result in an increased somatic Ca(2+) concentration, reflecting an increased firing rate linked to an increase in the pipette-cell conductance. Pipette effects on cell firing are traced to a combination of passive electrical coupling, opening of voltage- and Ca(2+)-sensitive K(+) channels (BK channels) after action potentials, and random activation of voltage-insensitive, presumably mechanosensitive, cationic channels. We conclude that, unless experimental conditions are optimized, cell-attached recordings in small neurons may report erroneous firing rates.
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19
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News in brief. Nat Methods 2011. [DOI: 10.1038/nmeth0511-371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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