1
|
Le Gratiet KL, Anderson CK, Puente N, Grandes P, Copas C, Nahirney PC, Delaney KR, Nashmi R. Differential Subcellular Distribution and Release Dynamics of Cotransmitted Cholinergic and GABAergic Synaptic Inputs Modify Dopaminergic Neuronal Excitability. J Neurosci 2022; 42:8670-8693. [PMID: 36195440 PMCID: PMC9671585 DOI: 10.1523/jneurosci.2514-21.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 08/31/2022] [Accepted: 09/02/2022] [Indexed: 11/21/2022] Open
Abstract
We identified three types of monosynaptic cholinergic inputs spatially arranged onto medial substantia nigra dopaminergic neurons in male and female mice: cotransmitted acetylcholine (ACh)/GABA, GABA-only, and ACh only. There was a predominant GABA-only conductance along lateral dendrites and soma-centered ACh/GABA cotransmission. In response to repeated stimulation, the GABA conductance found on lateral dendrites decremented less than the proximally located GABA conductance, and was more effective at inhibiting action potentials. While soma-localized ACh/GABA cotransmission showed depression of the GABA component with repeated stimulation, ACh-mediated nicotinic responses were largely maintained. We investigated whether this differential change in inhibitory/excitatory inputs leads to altered neuronal excitability. We found that a depolarizing current or glutamate preceded by cotransmitted ACh/GABA was more effective in eliciting an action potential compared with current, glutamate, or ACh/GABA alone. This enhanced excitability was abolished with nicotinic receptor inhibitors, and modulated by T- and L-type calcium channels, thus establishing that activity of multiple classes of ion channels integrates to shape neuronal excitability.SIGNIFICANCE STATEMENT Our laboratory has previously discovered a population of substantia nigra dopaminegic neurons (DA) that receive cotransmitted ACh and GABA. This study used subcellular optogenetic stimulation of cholinergic presynaptic terminals to map the functional ACh and GABA synaptic inputs across the somatodendritic extent of substantia nigra DA neurons. We determined spatially clustered GABA-only inputs on the lateral dendrites while cotransmitted ACh and GABA clustered close to the soma. We have shown that the action of GABA and ACh in cotransmission spatially clustered near the soma play a critical role in enhancing glutamate-mediated neuronal excitability through the activation of T- and L-type voltage-gated calcium channels.
Collapse
Affiliation(s)
| | | | - Nagore Puente
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country Universidad del Pais Vasco / Euskal Herriko Unibertsitatea, Leioa, Spain
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, E-48940, Leioa, Spain
| | - Pedro Grandes
- Department of Neurosciences, Faculty of Medicine and Nursing, University of the Basque Country Universidad del Pais Vasco / Euskal Herriko Unibertsitatea, Leioa, Spain
- Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, E-48940, Leioa, Spain
| | - Charlotte Copas
- Division of Medical Sciences
- Centre for Biomedical Research, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Patrick C Nahirney
- Division of Medical Sciences
- Centre for Biomedical Research, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Kerry R Delaney
- Department of Biology
- Centre for Biomedical Research, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Raad Nashmi
- Department of Biology
- Division of Medical Sciences
- Centre for Biomedical Research, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| |
Collapse
|
2
|
Cavalieri D, Angelova A, Islah A, Lopez C, Bocchio M, Bollmann Y, Baude A, Cossart R. CA1 pyramidal cell diversity is rootedin the time of neurogenesis. eLife 2021; 10:69270. [PMID: 34723790 PMCID: PMC8660020 DOI: 10.7554/elife.69270] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 10/31/2021] [Indexed: 11/18/2022] Open
Abstract
Cellular diversity supports the computational capacity and flexibility of cortical circuits. Accordingly, principal neurons at the CA1 output node of the murine hippocampus are increasingly recognized as a heterogeneous population. Their genes, molecular content, intrinsic morpho-physiology, connectivity, and function seem to segregate along the main anatomical axes of the hippocampus. Since these axes reflect the temporal order of principal cell neurogenesis, we directly examined the relationship between birthdate and CA1 pyramidal neuron diversity, focusing on the ventral hippocampus. We used a genetic fate-mapping approach that allowed tagging three groups of age-matched principal neurons: pioneer, early-, and late-born. Using a combination of neuroanatomy, slice physiology, connectivity tracing, and cFos staining in mice, we show that birthdate is a strong predictor of CA1 principal cell diversity. We unravel a subpopulation of pioneer neurons recruited in familiar environments with remarkable positioning, morpho-physiological features, and connectivity. Therefore, despite the expected plasticity of hippocampal circuits, given their role in learning and memory, the diversity of their main components is also partly determined at the earliest steps of development.
Collapse
Affiliation(s)
| | | | - Anas Islah
- INMED, INSERM Aix-Marseille University, marseille, France
| | | | | | | | - Agnès Baude
- INMED, French Institute of Health and Medical Research, Marseille, France
| | - Rosa Cossart
- INMED, French Institute of Health and Medical Research, Marseille, France
| |
Collapse
|
3
|
Circuit-Specific Dendritic Development in the Piriform Cortex. eNeuro 2020; 7:ENEURO.0083-20.2020. [PMID: 32457067 PMCID: PMC7307633 DOI: 10.1523/eneuro.0083-20.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/09/2020] [Accepted: 04/20/2020] [Indexed: 11/21/2022] Open
Abstract
Dendritic geometry is largely determined during postnatal development and has a substantial impact on neural function. In sensory processing, postnatal development of the dendritic tree is affected by two dominant circuit motifs, ascending sensory feedforward inputs and descending and local recurrent connections. In the three-layered anterior piriform cortex (aPCx), neurons in the sublayers 2a and 2b display vertical segregation of these two circuit motifs. Here, we combined electrophysiology, detailed morphometry, and Ca2+ imaging in acute mouse brain slices and modeling to study circuit-specific aspects of dendritic development. We observed that determination of branching complexity, dendritic length increases, and pruning occurred in distinct developmental phases. Layer 2a and layer 2b neurons displayed developmental phase-specific differences between their apical and basal dendritic trees related to differences in circuit incorporation. We further identified functional candidate mechanisms for circuit-specific differences in postnatal dendritic growth in sublayers 2a and 2b at the mesoscale and microscale levels. Already in the first postnatal week, functional connectivity of layer 2a and layer 2b neurons during early spontaneous network activity scales with differences in basal dendritic growth. During the early critical period of sensory plasticity in the piriform cortex, our data are consistent with a model that proposes a role for dendritic NMDA-spikes in selecting branches for survival during developmental pruning in apical dendrites. The different stages of the morphologic and functional developmental pattern differences between layer 2a and layer 2b neurons demonstrate the complex interplay between dendritic development and circuit specificity.
Collapse
|
4
|
Moore SJ, Murphy GG. The role of L-type calcium channels in neuronal excitability and aging. Neurobiol Learn Mem 2020; 173:107230. [PMID: 32407963 DOI: 10.1016/j.nlm.2020.107230] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 03/09/2020] [Accepted: 04/12/2020] [Indexed: 12/11/2022]
Abstract
Over the last two decades there has been significant progress towards understanding the neural substrates that underlie age-related cognitive decline. Although many of the exact molecular and cellular mechanisms have yet to be fully understood, there is consensus that alterations in neuronal calcium homeostasis contribute to age-related deficits in learning and memory. Furthermore, it is thought that the age-related changes in calcium homeostasis are driven, at least in part, by changes in calcium channel expression. In this review, we focus on the role of a specific class of calcium channels: L-type voltage-gated calcium channels (LVGCCs). We provide the reader with a general introduction to voltage-gated calcium channels, followed by a more detailed description of LVGCCs and how they serve to regulate neuronal excitability via the post burst afterhyperpolarization (AHP). We conclude by reviewing studies that link the slow component of the AHP to learning and memory, and discuss how age-related increases in LVGCC expression may underlie cognitive decline by mediating a decrease in neuronal excitability.
Collapse
Affiliation(s)
- Shannon J Moore
- Michigan Neuroscience Institute, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, United States; Department of Molecular and Integrative Physiology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, United States
| | - Geoffrey G Murphy
- Michigan Neuroscience Institute, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, United States; Department of Molecular and Integrative Physiology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, United States.
| |
Collapse
|
5
|
Yousuf H, Nye AN, Moyer JR. Heterogeneity of neuronal firing type and morphology in retrosplenial cortex of male F344 rats. J Neurophysiol 2020; 123:1849-1863. [PMID: 32267193 DOI: 10.1152/jn.00577.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The rodent granular retrosplenial cortex (gRSC) has reciprocal connections to the hippocampus to support fear memories. Although activity-dependent plasticity occurs within the RSC during memory formation, the intrinsic and morphological properties of RSC neurons are poorly understood. The present study used whole-cell recordings to examine intrinsic neuronal firing and morphology of neurons in layer 2/3 (L2/3) and layer 5 (L5) of the gRSC in adult male rats. Five different classifications were observed: regular-spiking (RS), regular-spiking afterdepolarization (RSADP), late-spiking (LS), burst-spiking (BS), and fast-spiking (FS) neurons. RSADP neurons were the most commonly observed neuronal class, identified by their robust spike frequency adaptation and pronounced afterdepolarization (ADP) following an action potential (AP). They also had the most extensive dendritic branching compared with other cell types. LS neurons were predominantly found in L2/3 and exhibited a long delay before onset of their initial AP. They also had reduced dendritic branching compared with other cell types. BS neurons were limited to L5 and generated an initial burst of two or more APs. FS neurons demonstrated sustained firing and little frequency adaptation and were the only nonpyramidal firing type. Relative to adults, RS neurons from juvenile rats (PND 14-30) lacked an ADP and were less excitable. Bath application of group 1 mGluR blockers attenuated the ADP in adult neurons. In other fear-related brain structures, the ADP has been shown to enhance excitability and synaptic plasticity. Thus, understanding cellular mechanisms of the gRSC will provide insight regarding its precise role in memory-related processes across the lifespan.NEW & NOTEWORTHY This is the first study to demonstrate that granular retrosplenial cortical (gRSC) neurons exhibit five distinctive firing types: regular spiking (RS), regular spiking with an afterdepolarization (RSADP), late spiking (LS), burst spiking (BS), and fast spiking (FS). RSADP neurons were the most frequently observed cell type in adult gRSC neurons. Interestingly, RS neurons without an ADP were most common in gRSC neurons of juvenile rats (PND 14-30). Thus, the ADP property, which was previously shown to enhance neuronal excitability, emerges during development.
Collapse
Affiliation(s)
- Hanna Yousuf
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Andrew N Nye
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - James R Moyer
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin.,Department of Biological Sciences University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| |
Collapse
|
6
|
Alshuaib S, Mosaddeghi J, Lin JW. Effects of levetiracetam on axon excitability and synaptic transmission at the crayfish neuromuscular junction. Synapse 2020; 74:e22154. [PMID: 32189403 DOI: 10.1002/syn.22154] [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: 12/11/2019] [Revised: 02/24/2020] [Accepted: 03/15/2020] [Indexed: 11/06/2022]
Abstract
Levetiracetam (LEV) is a widely prescribed antiepileptic drug, but its actions on neuronal function are not fully characterized. Since this drug is believed to enter neurons by binding to a vesicular protein during endocytosis, we used motor axons of the crayfish opener neuromuscular junction to examine potential impacts of LEV on axon excitability. Two electrode current clamp from the inhibitory axon of the opener showed that LEV reduced action potential (AP) amplitude (APamp ) and suppressed synaptic transmission, although the latter occurred with a longer delay than the reduction in APamp . Comparison of antidromic and orthodromic conducting APs in LEV suggested that this drug preferentially reduced excitability of the proximal axon, despite the expectation that it entered the axon at the terminals and should affect the distal branches first. Results presented here suggest that LEV modulates axonal excitability, which may in turn contribute to its antiepileptic effects.
Collapse
Affiliation(s)
| | | | - Jen-We Lin
- Department of Biology, Boston University, Boston, MA, USA
| |
Collapse
|
7
|
Yousuf H, Ehlers VL, Sehgal M, Song C, Moyer JR. Modulation of intrinsic excitability as a function of learning within the fear conditioning circuit. Neurobiol Learn Mem 2019; 167:107132. [PMID: 31821881 DOI: 10.1016/j.nlm.2019.107132] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/27/2019] [Indexed: 11/28/2022]
Abstract
Experience-dependent neuronal plasticity is a fundamental substrate of learning and memory. Intrinsic excitability is a form of neuronal plasticity that can be altered by learning and indicates the pattern of neuronal responding to external stimuli (e.g. a learning or synaptic event). Associative fear conditioning is one form of learning that alters intrinsic excitability, reflecting an experience-dependent change in neuronal function. After fear conditioning, intrinsic excitability changes are evident in brain regions that are a critical part of the fear circuit, including the amygdala, hippocampus, retrosplenial cortex, and prefrontal cortex. Some of these changes are transient and/or reversed by extinction as well as learning-specific (i.e. they are not observed in neurons from control animals). This review will explore how intrinsic neuronal excitability changes within brain structures that are critical for fear learning, and it will also discuss evidence promoting intrinsic excitability as a vital mechanism of associative fear memories. This work has raised interesting questions regarding the role of fear learning in changes of intrinsic excitability within specific subpopulations of neurons, including those that express immediate early genes and thus demonstrate experience-dependent activity, as well as in neurons classified as having a specific firing type (e.g. burst-spiking vs. regular-spiking). These findings have interesting implications for how intrinsic excitability can serve as a neural substrate of learning and memory, and suggest that intrinsic plasticity within specific subpopulations of neurons may promote consolidation of the memory trace in a flexible and efficient manner.
Collapse
Affiliation(s)
- Hanna Yousuf
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - Vanessa L Ehlers
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - Megha Sehgal
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - Chenghui Song
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - James R Moyer
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA; Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA.
| |
Collapse
|
8
|
Porter JT, Sepulveda-Orengo MT. Learning-induced intrinsic and synaptic plasticity in the rodent medial prefrontal cortex. Neurobiol Learn Mem 2019; 169:107117. [PMID: 31765801 DOI: 10.1016/j.nlm.2019.107117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 11/06/2019] [Accepted: 11/14/2019] [Indexed: 01/12/2023]
Abstract
In rodents, the anterior cingulate (ACC), prelimbic (PL), and infralimbic cortex (IL) comprise the medial prefrontal cortex (mPFC). Through extensive connections with cortical and subcortical structures, the mPFC plays a key modulatory role in the neuronal circuits underlying associative fear and reward learning. In this article, we have compiled the evidence that associative learning induces plasticity in both the intrinsic and synaptic excitability of mPFC neurons to modulate conditioned fear and cocaine seeking behavior. The literature highlights the accumulating evidence that plasticity in the intrinsic excitability of mPFC neurons represents a major cellular mechanism that interacts with synaptic changes to alter the impact of the mPFC on fear and reward circuits.
Collapse
Affiliation(s)
- James T Porter
- Dept of Basic Sciences, Ponce Research Institute, Ponce Health Sciences University, Ponce, PR 00732, United States.
| | - Marian T Sepulveda-Orengo
- Dept of Basic Sciences, Ponce Research Institute, Ponce Health Sciences University, Ponce, PR 00732, United States
| |
Collapse
|
9
|
Dunn AR, Kaczorowski CC. Regulation of intrinsic excitability: Roles for learning and memory, aging and Alzheimer's disease, and genetic diversity. Neurobiol Learn Mem 2019; 164:107069. [PMID: 31442579 DOI: 10.1016/j.nlm.2019.107069] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/09/2019] [Accepted: 08/17/2019] [Indexed: 12/28/2022]
Abstract
Plasticity of intrinsic neuronal excitability facilitates learning and memory across multiple species, with aberrant modulation of this process being linked to the development of neurological symptoms in models of cognitive aging and Alzheimer's disease. Learning-related increases in intrinsic excitability of neurons occurs in a variety of brain regions, and is generally thought to promote information processing and storage through enhancement of synaptic throughput and induction of synaptic plasticity. Experience-dependent changes in intrinsic neuronal excitability rely on activity-dependent gene expression patterns, which can be influenced by genetic and environmental factors, aging, and disease. Reductions in baseline intrinsic excitability, as well as aberrant plasticity of intrinsic neuronal excitability and in some cases pathological hyperexcitability, have been associated with cognitive deficits in animal models of both normal cognitive aging and Alzheimer's disease. Genetic factors that modulate plasticity of intrinsic excitability likely underlie individual differences in cognitive function and susceptibility to cognitive decline. Thus, targeting molecular mediators that either control baseline intrinsic neuronal excitability, subserve learning-related intrinsic neuronal plasticity, and/or promote resilience may be a promising therapeutic strategy for maintaining cognitive function in aging and disease. In this review, we discuss the complementary relationship between intrinsic excitability and learning, with a particular focus on how this relationship varies as a function of age, disease state, and genetic make-up, and how targeting these factors may help to further elucidate our understanding of the role of intrinsic excitability in cognitive function and cognitive decline.
Collapse
Affiliation(s)
- Amy R Dunn
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | | |
Collapse
|
10
|
Gouwens NW, Sorensen SA, Berg J, Lee C, Jarsky T, Ting J, Sunkin SM, Feng D, Anastassiou CA, Barkan E, Bickley K, Blesie N, Braun T, Brouner K, Budzillo A, Caldejon S, Casper T, Castelli D, Chong P, Crichton K, Cuhaciyan C, Daigle TL, Dalley R, Dee N, Desta T, Ding SL, Dingman S, Doperalski A, Dotson N, Egdorf T, Fisher M, de Frates RA, Garren E, Garwood M, Gary A, Gaudreault N, Godfrey K, Gorham M, Gu H, Habel C, Hadley K, Harrington J, Harris JA, Henry A, Hill D, Josephsen S, Kebede S, Kim L, Kroll M, Lee B, Lemon T, Link KE, Liu X, Long B, Mann R, McGraw M, Mihalas S, Mukora A, Murphy GJ, Ng L, Ngo K, Nguyen TN, Nicovich PR, Oldre A, Park D, Parry S, Perkins J, Potekhina L, Reid D, Robertson M, Sandman D, Schroedter M, Slaughterbeck C, Soler-Llavina G, Sulc J, Szafer A, Tasic B, Taskin N, Teeter C, Thatra N, Tung H, Wakeman W, Williams G, Young R, Zhou Z, Farrell C, Peng H, Hawrylycz MJ, Lein E, Ng L, Arkhipov A, Bernard A, Phillips JW, Zeng H, Koch C. Classification of electrophysiological and morphological neuron types in the mouse visual cortex. Nat Neurosci 2019; 22:1182-1195. [PMID: 31209381 PMCID: PMC8078853 DOI: 10.1038/s41593-019-0417-0] [Citation(s) in RCA: 233] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 04/25/2019] [Indexed: 12/21/2022]
Abstract
Understanding the diversity of cell types in the brain has been an enduring challenge and requires detailed characterization of individual neurons in multiple dimensions. To systematically profile morpho-electric properties of mammalian neurons, we established a single-cell characterization pipeline using standardized patch-clamp recordings in brain slices and biocytin-based neuronal reconstructions. We built a publicly accessible online database, the Allen Cell Types Database, to display these datasets. Intrinsic physiological properties were measured from 1,938 neurons from the adult laboratory mouse visual cortex, morphological properties were measured from 461 reconstructed neurons, and 452 neurons had both measurements available. Quantitative features were used to classify neurons into distinct types using unsupervised methods. We established a taxonomy of morphologically and electrophysiologically defined cell types for this region of the cortex, with 17 electrophysiological types, 38 morphological types and 46 morpho-electric types. There was good correspondence with previously defined transcriptomic cell types and subclasses using the same transgenic mouse lines.
Collapse
Affiliation(s)
| | | | - Jim Berg
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Changkyu Lee
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Tim Jarsky
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Jonathan Ting
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Susan M Sunkin
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - David Feng
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - Eliza Barkan
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Kris Bickley
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Nicole Blesie
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Thomas Braun
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Krissy Brouner
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Agata Budzillo
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - Tamara Casper
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Dan Castelli
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Peter Chong
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | | | - Tanya L Daigle
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Rachel Dalley
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Nick Dee
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Tsega Desta
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Song-Lin Ding
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Samuel Dingman
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | | | - Tom Egdorf
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Michael Fisher
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - Emma Garren
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - Amanda Gary
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - Keith Godfrey
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Melissa Gorham
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Hong Gu
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Caroline Habel
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Kristen Hadley
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - Julie A Harris
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Alex Henry
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - DiJon Hill
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Sam Josephsen
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Sara Kebede
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Lisa Kim
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Matthew Kroll
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Brian Lee
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Tracy Lemon
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - Xiaoxiao Liu
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Brian Long
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Rusty Mann
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Medea McGraw
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Stefan Mihalas
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Alice Mukora
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Gabe J Murphy
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Lindsay Ng
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Kiet Ngo
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | | | - Aaron Oldre
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Daniel Park
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Sheana Parry
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Jed Perkins
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - David Reid
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - David Sandman
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | | | | | - Josef Sulc
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Aaron Szafer
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Bosiljka Tasic
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Naz Taskin
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Corinne Teeter
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - Herman Tung
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Wayne Wakeman
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Grace Williams
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Rob Young
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Zhi Zhou
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Colin Farrell
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Hanchuan Peng
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - Ed Lein
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Lydia Ng
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Anton Arkhipov
- Allen Institute for Brain Science, Seattle, Washington, USA
| | - Amy Bernard
- Allen Institute for Brain Science, Seattle, Washington, USA
| | | | - Hongkui Zeng
- Allen Institute for Brain Science, Seattle, Washington, USA.
| | - Christof Koch
- Allen Institute for Brain Science, Seattle, Washington, USA
| |
Collapse
|
11
|
Cerebellar Stellate Cell Excitability Is Coordinated by Shifts in the Gating Behavior of Voltage-Gated Na + and A-Type K + Channels. eNeuro 2019; 6:ENEURO.0126-19.2019. [PMID: 31110133 PMCID: PMC6553571 DOI: 10.1523/eneuro.0126-19.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 04/26/2019] [Accepted: 05/13/2019] [Indexed: 01/12/2023] Open
Abstract
Neuronal excitability in the vertebrate brain is governed by the coordinated activity of both ligand- and voltage-gated ion channels. In the cerebellum, spontaneous action potential (AP) firing of inhibitory stellate cells (SCs) is variable, typically operating within the 5- to 30-Hz frequency range. AP frequency is shaped by the activity of somatodendritic A-type K+ channels and the inhibitory effect of GABAergic transmission. An added complication, however, is that whole-cell recording from SCs induces a time-dependent and sustained increase in membrane excitability making it difficult to define the full range of firing rates. Here, we show that whole-cell recording in cerebellar SCs of both male and female mice augments firing rates by reducing the membrane potential at which APs are initiated. AP threshold is lowered due to a hyperpolarizing shift in the gating behavior of voltage-gated Na+ channels. Whole-cell recording also elicits a hyperpolarizing shift in the gating behavior of A-type K+ channels which contributes to increased firing rates. Hodgkin–Huxley modeling and pharmacological experiments reveal that gating shifts in A-type K+ channel activity do not impact AP threshold, but rather promote channel inactivation which removes restraint on the upper limit of firing rates. Taken together, our work reveals an unappreciated impact of voltage-gated Na+ channels that work in coordination with A-type K+ channels to regulate the firing frequency of cerebellar SCs.
Collapse
|
12
|
Church TW, Brown JT, Marrion NV. β 3-Adrenergic receptor-dependent modulation of the medium afterhyperpolarization in rat hippocampal CA1 pyramidal neurons. J Neurophysiol 2019; 121:773-784. [PMID: 30625002 DOI: 10.1152/jn.00334.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Action potential firing in hippocampal pyramidal neurons is regulated by generation of an afterhyperpolarization (AHP). Three phases of AHP are recognized, with the fast AHP regulating action potential firing at the onset of a burst and the medium and slow AHPs supressing action potential firing over hundreds of milliseconds and seconds, respectively. Activation of β-adrenergic receptors suppresses the slow AHP by a protein kinase A-dependent pathway. However, little is known regarding modulation of the medium AHP. Application of the selective β-adrenergic receptor agonist isoproterenol suppressed both the medium and slow AHPs evoked in rat CA1 hippocampal pyramidal neurons recorded from slices maintained in organotypic culture. Suppression of the slow AHP was mimicked by intracellular application of cAMP, with the suppression of the medium AHP by isoproterenol still being evident in cAMP-dialyzed cells. Suppression of both the medium and slow AHPs was antagonized by the β-adrenergic receptor antagonist propranolol. The effect of isoproterenol to suppress the medium AHP was mimicked by two β3-adrenergic receptor agonists, BRL37344 and SR58611A. The medium AHP was mediated by activation of small-conductance calcium-activated K+ channels and deactivation of H channels at the resting membrane potential. Suppression of the medium AHP by isoproterenol was reduced by pretreating cells with the H-channel blocker ZD7288. These data suggest that activation of β3-adrenergic receptors inhibits H channels, which suppresses the medium AHP in CA1 hippocampal neurons by utilizing a pathway that is independent of a rise in intracellular cAMP. This finding highlights a potential new target in modulating H-channel activity and thereby neuronal excitability. NEW & NOTEWORTHY The noradrenergic input into the hippocampus is involved in modulating long-term synaptic plasticity and is implicated in learning and memory. We demonstrate that activation of functional β3-adrenergic receptors suppresses the medium afterhyperpolarization in hippocampal pyramidal neurons. This finding provides an additional mechanism to increase action potential firing frequency, where neuronal excitability is likely to be crucial in cognition and memory.
Collapse
Affiliation(s)
- Timothy W Church
- School of Physiology, Pharmacology and Neuroscience, University of Bristol , Bristol , United Kingdom
| | - Jon T Brown
- University of Exeter Medical School , Exeter , United Kingdom
| | - Neil V Marrion
- School of Physiology, Pharmacology and Neuroscience, University of Bristol , Bristol , United Kingdom
| |
Collapse
|
13
|
Cell-Type-Specific Changes in Intrinsic Excitability in the Subiculum following Learning and Exposure to Novel Environmental Contexts. eNeuro 2019; 5:eN-NWR-0484-18. [PMID: 30627661 PMCID: PMC6325565 DOI: 10.1523/eneuro.0484-18.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 12/29/2022] Open
Abstract
The subiculum is the main target of the hippocampal region CA1 and is the principle output region of the hippocampus. The subiculum is critical to learning and memory, although it has been relatively understudied. There are two functional types of principle neurons within the subiculum: regular spiking (RS) and burst spiking (BS) neurons. To determine whether these cell types are differentially modified by learning-related experience, we performed whole-cell patch clamp recordings from male mouse brain slices following contextual fear conditioning (FC) and memory retrieval relative to a number of control behavioral paradigms. RS cells, but not BS cells, displayed a greater degree of experience-related plasticity in intrinsic excitability measures [afterhyperpolarization (AHP), input resistance (Rinput), current required to elicit a spike], with fear conditioned animals having generally more excitable RS cells compared to naïve controls. Furthermore, we found that the relative proportion of RS to BS neurons is modified by the type of exposure, with the lowest proportion of BS subicular cells occurring in animals that underwent contextual FC followed by a retrieval test. These studies indicate that pyramidal neurons in the subiculum undergo experience- and learning-related plasticity in intrinsic properties in a cell-type-specific manner. As BS and RS cells are thought to convey distinct types of information, this plasticity may be particularly important in encoding, consolidating, and recalling spatial information by modulating information flow from the hippocampus to cortical regions.
Collapse
|
14
|
Yu S, Lin Z, Xiao Z. [Changes of membrane properties and synaptic stability of rat retinal ganglion cells during postnatal development]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2018; 38:1100-1106. [PMID: 30377110 DOI: 10.12122/j.issn.1673-4254.2018.09.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the changes in the membrane properties and synaptic stability of the rat retinal ganglion cells (RGCs) during postnatal development. METHODS Whole-cell patch-clamp technique was used to record the action potentials (AP) and miniature excitatory postsynaptic currents (mEPSC) of SD rat RGCs at postnatal days 7, 14 and 40. The active and passive membrane properties and the synaptic stability (measured by the amplitude, frequency, rise time and decay time of mEPSC) of the RGCs were analyzed using Patchmaster software. RESULTS Comparison of the RGCs in SD rats across different postnatal ages revealed significant changes in the electrophysiological characteristics of the RGCs during postnatal development. The discharge rate was significantly greater while the AP half-peak width was significantly smaller at postnatal day 15 (P15) than at P7 (P < 0.01), but were both similar between P15 and P40 (P=0.086); in terms of the passive membrane properties, the membrane time constant gradually decreased during the development. The frequency of mEPSCs increased significantly over time during postnatal development (P < 0.01), but was similar between P15 and P40 rats. CONCLUSIONS In SD rats, the membrane properties and synaptic stability of the RGCs undergo alterations following a specific pattern, which highlights a critical period where distinct changes occur in the electrophysiological characteristics of RGCs, followed by gradual stabilization over time. Such changes in the electrophysiological characteristics represent the basic characteristics of RGCs for visual signal processing, and understanding of this mechanism may provide insights into the exact role of the RGC in visual information processing.
Collapse
Affiliation(s)
- Siqi Yu
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Zhengrong Lin
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Zhongju Xiao
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| |
Collapse
|
15
|
Tebaykin D, Tripathy SJ, Binnion N, Li B, Gerkin RC, Pavlidis P. Modeling sources of interlaboratory variability in electrophysiological properties of mammalian neurons. J Neurophysiol 2017; 119:1329-1339. [PMID: 29357465 DOI: 10.1152/jn.00604.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Patch-clamp electrophysiology is widely used to characterize neuronal electrical phenotypes. However, there are no standard experimental conditions for in vitro whole cell patch-clamp electrophysiology, complicating direct comparisons between data sets. In this study, we sought to understand how basic experimental conditions differ among laboratories and how these differences might impact measurements of electrophysiological parameters. We curated the compositions of external bath solutions (artificial cerebrospinal fluid), internal pipette solutions, and other methodological details such as animal strain and age from 509 published neurophysiology articles studying rodent neurons. We found that very few articles used the exact same experimental solutions as any other, and some solution differences stem from recipe inheritance from advisor to advisee as well as changing trends over the years. Next, we used statistical models to understand how the use of different experimental conditions impacts downstream electrophysiological measurements such as resting potential and action potential width. Although these experimental condition features could explain up to 43% of the study-to-study variance in electrophysiological parameters, the majority of the variability was left unexplained. Our results suggest that there are likely additional experimental factors that contribute to cross-laboratory electrophysiological variability, and identifying and addressing these will be important to future efforts to assemble consensus descriptions of neurophysiological phenotypes for mammalian cell types. NEW & NOTEWORTHY This article describes how using different experimental methods during patch-clamp electrophysiology impacts downstream physiological measurements. We characterized how methodologies and experimental solutions differ across articles. We found that differences in methods can explain some, but not all, of the study-to-study variance in electrophysiological measurements. Explicitly accounting for methodological differences using statistical models can help correct downstream electrophysiological measurements for cross-laboratory methodology differences.
Collapse
Affiliation(s)
- Dmitry Tebaykin
- Department of Psychiatry and Michael Smith Laboratories, University of British Columbia , Vancouver, British Columbia , Canada.,Graduate Program in Bioinformatics, University of British Columbia , Vancouver, British Columbia , Canada
| | - Shreejoy J Tripathy
- Department of Psychiatry and Michael Smith Laboratories, University of British Columbia , Vancouver, British Columbia , Canada
| | - Nathalie Binnion
- Department of Psychiatry and Michael Smith Laboratories, University of British Columbia , Vancouver, British Columbia , Canada
| | - Brenna Li
- Department of Psychiatry and Michael Smith Laboratories, University of British Columbia , Vancouver, British Columbia , Canada
| | - Richard C Gerkin
- School of Life Sciences, Arizona State University , Tempe, Arizona
| | - Paul Pavlidis
- Department of Psychiatry and Michael Smith Laboratories, University of British Columbia , Vancouver, British Columbia , Canada
| |
Collapse
|
16
|
Beining M, Mongiat LA, Schwarzacher SW, Cuntz H, Jedlicka P. T2N as a new tool for robust electrophysiological modeling demonstrated for mature and adult-born dentate granule cells. eLife 2017; 6:e26517. [PMID: 29165247 PMCID: PMC5737656 DOI: 10.7554/elife.26517] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 11/21/2017] [Indexed: 12/18/2022] Open
Abstract
Compartmental models are the theoretical tool of choice for understanding single neuron computations. However, many models are incomplete, built ad hoc and require tuning for each novel condition rendering them of limited usability. Here, we present T2N, a powerful interface to control NEURON with Matlab and TREES toolbox, which supports generating models stable over a broad range of reconstructed and synthetic morphologies. We illustrate this for a novel, highly detailed active model of dentate granule cells (GCs) replicating a wide palette of experiments from various labs. By implementing known differences in ion channel composition and morphology, our model reproduces data from mouse or rat, mature or adult-born GCs as well as pharmacological interventions and epileptic conditions. This work sets a new benchmark for detailed compartmental modeling. T2N is suitable for creating robust models useful for large-scale networks that could lead to novel predictions. We discuss possible T2N application in degeneracy studies.
Collapse
Affiliation(s)
- Marcel Beining
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck SocietyFrankfurtGermany
- Frankfurt Institute for Advanced StudiesFrankfurtGermany
- Institute of Clinical Neuroanatomy, Neuroscience CenterGoethe UniversityFrankfurtGermany
- Faculty of BiosciencesGoethe UniversityFrankfurtGermany
| | - Lucas Alberto Mongiat
- Instituto de Investigación en Biodiversidad y MedioambienteUniversidad Nacional del Comahue-CONICETSan Carlos de BarilocheArgentina
| | | | - Hermann Cuntz
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck SocietyFrankfurtGermany
- Frankfurt Institute for Advanced StudiesFrankfurtGermany
| | - Peter Jedlicka
- Institute of Clinical Neuroanatomy, Neuroscience CenterGoethe UniversityFrankfurtGermany
| |
Collapse
|
17
|
Vera J, Alcayaga J, Sanhueza M. Competition between Persistent Na + and Muscarine-Sensitive K + Currents Shapes Perithreshold Resonance and Spike Tuning in CA1 Pyramidal Neurons. Front Cell Neurosci 2017; 11:61. [PMID: 28337126 PMCID: PMC5340745 DOI: 10.3389/fncel.2017.00061] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 02/22/2017] [Indexed: 11/28/2022] Open
Abstract
Neurons from many brain regions display intrinsic subthreshold theta-resonance, responding preferentially to theta-frequency oscillatory stimuli. Resonance may contribute to selective communication among neurons and to orchestrate brain rhythms. CA1 pyramidal neurons receive theta activity, generating place fields. In these neurons the expression of perithreshold frequency preference is controversial, particularly in the spiking regime, with evidence favoring either non-resonant (integrator-like) or resonant behavior. Perithreshold dynamics depends on the persistent Na+ current INaP developing above −70 mV and the muscarine-sensitive K+ current IM activating above −60 mV. We conducted current and voltage clamp experiments in slices to investigate perithreshold excitability of CA1 neurons under oscillatory stimulation. Around 20% of neurons displayed perithreshold resonance that is expressed in spiking. The remaining neurons (~80%) acted as low-pass filters lacking frequency preference. Paired voltage clamp measurement of INaP and IM showed that perithreshold activation of IM is in general low while INaP is high enough to depolarize neurons toward threshold before resonance expression, explaining the most abundant non-resonant perithreshold behavior. Partial blockade of INaP by pharmacological tools or dynamic clamp changed non-resonant to resonant behavior. Furthermore, shifting IM activation toward hyperpolarized potentials by dynamic clamp also transformed non-resonant neurons into resonant ones. We propose that the relative levels of INaP and IM control perithreshold behavior of CA1 neurons constituting a gating mechanism for theta resonance in the spiking regime. Both currents are regulated by intracellular signaling and neuromodulators which may allow dynamic switching of perithreshold behavior between resonant and non-resonant.
Collapse
Affiliation(s)
- Jorge Vera
- Department of Biology, Cell Physiology Center, University of Chile Santiago, Chile
| | - Julio Alcayaga
- Department of Biology, Cell Physiology Center, University of Chile Santiago, Chile
| | - Magdalena Sanhueza
- Department of Biology, Cell Physiology Center, University of Chile Santiago, Chile
| |
Collapse
|
18
|
Age-dependent regulation of GABA transmission by kappa opioid receptors in the basolateral amygdala of Sprague-Dawley rats. Neuropharmacology 2017; 117:124-133. [PMID: 28163104 DOI: 10.1016/j.neuropharm.2017.01.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 01/26/2017] [Accepted: 01/29/2017] [Indexed: 12/17/2022]
Abstract
Anxiety disorders are one of the most common and debilitating mental illnesses worldwide. Growing evidence indicates an age-dependent rise in the incidence of anxiety disorders from adolescence through adulthood, suggestive of underlying neurodevelopmental mechanisms. Kappa opioid receptors (KORs) are known to contribute to the development and expression of anxiety; however, the functional role of KORs in the basolateral amygdala (BLA), a brain structure critical in mediating anxiety, particularly across ontogeny, are unknown. Using whole-cell patch-clamp electrophysiology in acute brain slices from adolescent (postnatal day (P) 30-45) and adult (P60+) male Sprague-Dawley rats, we found that the KOR agonist, U69593, increased the frequency of GABAA-mediated spontaneous inhibitory postsynaptic currents (sIPSCs) in the adolescent BLA, without an effect in the adult BLA or on sIPSC amplitude at either age. The KOR effect was blocked by the KOR antagonist, nor-BNI, which alone did not alter GABA transmission at either age, and the effect of the KOR agonist was TTX-sensitive. Additionally, KOR activation did not alter glutamatergic transmission in the BLA at either age. In contrast, U69593 inhibited sIPSC frequency in the central amygdala (CeA) at both ages, without altering sIPSC amplitude. Western blot analysis of KOR expression indicated that KOR levels were not different between the two ages in either the BLA or CeA. This is the first study to provide compelling evidence for a novel and unique neuromodulatory switch in one of the primary brain regions involved in initiating and mediating anxiety that may contribute to the ontogenic rise in anxiety disorders.
Collapse
|
19
|
Giovannini F, Knauer B, Yoshida M, Buhry L. The CAN-In network: A biologically inspired model for self-sustained theta oscillations and memory maintenance in the hippocampus. Hippocampus 2017; 27:450-463. [PMID: 28052448 DOI: 10.1002/hipo.22704] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2016] [Indexed: 11/05/2022]
Abstract
During working memory tasks, the hippocampus exhibits synchronous theta-band activity, which is thought to be correlated with the short-term memory maintenance of salient stimuli. Recent studies indicate that the hippocampus contains the necessary circuitry allowing it to generate and sustain theta oscillations without the need of extrinsic drive. However, the cellular and network mechanisms supporting synchronous rhythmic activity are far from being fully understood. Based on electrophysiological recordings from hippocampal pyramidal CA1 cells, we present a possible mechanism for the maintenance of such rhythmic theta-band activity in the isolated hippocampus. Our model network, based on the Hodgkin-Huxley formalism, comprising pyramidal neurons equipped with calcium-activated nonspecific cationic (CAN) ion channels, is able to generate and sustain synchronized theta oscillations (4-12 Hz), following a transient stimulation. The synchronous network activity is maintained by an intrinsic CAN current (ICAN ), in the absence of constant external input. When connecting the pyramidal-CAN network to fast-spiking inhibitory interneurons, the dynamics of the model reveal that feedback inhibition improves the robustness of fast theta oscillations, by tightening the synchronization of the pyramidal CAN neurons. The frequency and power of the theta oscillations are both modulated by the intensity of the ICAN , which allows for a wide range of oscillation rates within the theta band. This biologically plausible mechanism for the maintenance of synchronous theta oscillations in the hippocampus aims at extending the traditional models of septum-driven hippocampal rhythmic activity. © 2017 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Francesco Giovannini
- Neurosys Team, INRIA CR Nancy Grand Est, Villers-lès-Nancy, France.,Neurosys Team, CNRS, LORIA UMR 7503, Vandoeuvre-lès-Nancy, France.,Université de Lorraine, LORIA UMR 7503, Vandoeuvre-lès-Nancy, France
| | - Beate Knauer
- Research School, Ruhr University Bochum, Bochum, Germany.,Department of Physiology, Monash University, Clayton, VIC, Australia
| | - Motoharu Yoshida
- Leibniz Institute for Neurobiology (LIN) and German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
| | - Laure Buhry
- Neurosys Team, INRIA CR Nancy Grand Est, Villers-lès-Nancy, France.,Neurosys Team, CNRS, LORIA UMR 7503, Vandoeuvre-lès-Nancy, France.,Université de Lorraine, LORIA UMR 7503, Vandoeuvre-lès-Nancy, France
| |
Collapse
|
20
|
Engel D. Subcellular Patch-clamp Recordings from the Somatodendritic Domain of Nigral Dopamine Neurons. J Vis Exp 2016. [PMID: 27842379 PMCID: PMC5226116 DOI: 10.3791/54601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Dendrites of dopaminergic neurons receive and convey synaptic input, support action potential back-propagation and neurotransmitter release. Understanding these fundamental functions will shed light on the information transfer in these neurons. Dendritic patch-clamp recordings provide the possibility to directly examine the electrical properties of dendrites and underlying voltage-gated ion channels. However, these fine structures are not easily accessible to patch pipettes because of their small diameter. This report describes a step-by-step procedure to collect stable and reliable recordings from the dendrites of dopaminergic neurons in acute slices. Electrophysiological measurements are combined with post hoc recovery of cell morphology. Successful experiments rely on improved preparation of slices, solutions and pipettes, adequate adjustment of the optics and stability of the pipette in contact with the recorded structure. Standard principles of somatic patch-clamp recording are applied to dendrites but with a gentler approach of the pipette. These versatile techniques can be implemented to address various questions concerning the excitable properties of dendrites.
Collapse
|
21
|
Villanueva-Castillo C, Tecuatl C, Herrera-López G, Galván EJ. Aging-related impairments of hippocampal mossy fibers synapses on CA3 pyramidal cells. Neurobiol Aging 2016; 49:119-137. [PMID: 27794263 DOI: 10.1016/j.neurobiolaging.2016.09.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 09/15/2016] [Accepted: 09/17/2016] [Indexed: 11/16/2022]
Abstract
The network interaction between the dentate gyrus and area CA3 of the hippocampus is responsible for pattern separation, a process that underlies the formation of new memories, and which is naturally diminished in the aged brain. At the cellular level, aging is accompanied by a progression of biochemical modifications that ultimately affects its ability to generate and consolidate long-term potentiation. Although the synapse between dentate gyrus via the mossy fibers (MFs) onto CA3 neurons has been subject of extensive studies, the question of how aging affects the MF-CA3 synapse is still unsolved. Extracellular and whole-cell recordings from acute hippocampal slices of aged Wistar rats (34 ± 2 months old) show that aging is accompanied by a reduction in the interneuron-mediated inhibitory mechanisms of area CA3. Several MF-mediated forms of short-term plasticity, MF long-term potentiation and at least one of the critical signaling cascades necessary for potentiation are also compromised in the aged brain. An analysis of the spontaneous glutamatergic and gamma-aminobutyric acid-mediated currents on CA3 cells reveal a dramatic alteration in amplitude and frequency of the nonevoked events. CA3 cells also exhibited increased intrinsic excitability. Together, these results demonstrate that aging is accompanied by a decrease in the GABAergic inhibition, reduced expression of short- and long-term forms of synaptic plasticity, and increased intrinsic excitability.
Collapse
Affiliation(s)
| | - Carolina Tecuatl
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, México
| | | | - Emilio J Galván
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, México.
| |
Collapse
|
22
|
Cannabinoid Type 2 Receptors Mediate a Cell Type-Specific Plasticity in the Hippocampus. Neuron 2016; 90:795-809. [PMID: 27133464 DOI: 10.1016/j.neuron.2016.03.034] [Citation(s) in RCA: 203] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 01/20/2016] [Accepted: 03/18/2016] [Indexed: 02/07/2023]
Abstract
Endocannabinoids (eCBs) exert major control over neuronal activity by activating cannabinoid receptors (CBRs). The functionality of the eCB system is primarily ascribed to the well-documented retrograde activation of presynaptic CB1Rs. We find that action potential-driven eCB release leads to a long-lasting membrane potential hyperpolarization in hippocampal principal cells that is independent of CB1Rs. The hyperpolarization, which is specific to CA3 and CA2 pyramidal cells (PCs), depends on the activation of neuronal CB2Rs, as shown by a combined pharmacogenetic and immunohistochemical approach. Upon activation, they modulate the activity of the sodium-bicarbonate co-transporter, leading to a hyperpolarization of the neuron. CB2R activation occurred in a purely self-regulatory manner, robustly altered the input/output function of CA3 PCs, and modulated gamma oscillations in vivo. To conclude, we describe a cell type-specific plasticity mechanism in the hippocampus that provides evidence for the neuronal expression of CB2Rs and emphasizes their importance in basic neuronal transmission.
Collapse
|
23
|
Nimitvilai S, Lopez MF, Mulholland PJ, Woodward JJ. Chronic Intermittent Ethanol Exposure Enhances the Excitability and Synaptic Plasticity of Lateral Orbitofrontal Cortex Neurons and Induces a Tolerance to the Acute Inhibitory Actions of Ethanol. Neuropsychopharmacology 2016; 41:1112-27. [PMID: 26286839 PMCID: PMC4748436 DOI: 10.1038/npp.2015.250] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Revised: 08/14/2015] [Accepted: 08/15/2015] [Indexed: 02/07/2023]
Abstract
Alcoholism is associated with changes in brain reward and control systems, including the prefrontal cortex. In prefrontal areas, the orbitofrontal cortex (OFC) has been suggested to have an important role in the development of alcohol-abuse disorders and studies from this laboratory demonstrate that OFC-mediated behaviors are impaired in alcohol-dependent animals. However, it is not known whether chronic alcohol (ethanol) exposure alters the fundamental properties of OFC neurons. In this study, mice were exposed to repeated cycles of chronic intermittent ethanol (CIE) exposure to induce dependence and whole-cell patch-clamp electrophysiology was used to examine the effects of CIE treatment on lateral OFC (lOFC) neuron excitability, synaptic transmission, and plasticity. Repeated cycles of CIE exposure and withdrawal enhanced current-evoked action potential (AP) spiking and this was accompanied by a reduction in the after-hyperpolarization and a decrease in the functional activity of SK channels. CIE mice also showed an increase in the AMPA/NMDA ratio, and this was associated with an increase in GluA1/GluA2 AMPA receptor expression and a decrease in GluN2B NMDA receptor subunits. Following CIE treatment, lOFC neurons displayed a persistent long-term potentiation of glutamatergic synaptic transmission following a spike-timing-dependent protocol. Lastly, CIE treatment diminished the inhibitory effect of acute ethanol on AP spiking of lOFC neurons and reduced expression of the GlyT1 transporter. Taken together, these results suggest that chronic exposure to ethanol leads to enhanced intrinsic excitability and glutamatergic synaptic signaling of lOFC neurons. These alterations may contribute to the impairment of OFC-dependent behaviors in alcohol-dependent individuals.
Collapse
Affiliation(s)
- Sudarat Nimitvilai
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - Marcelo F Lopez
- Addiction Sciences Division, Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA
| | - Patrick J Mulholland
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
- Addiction Sciences Division, Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA
| | - John J Woodward
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
- Addiction Sciences Division, Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA
| |
Collapse
|
24
|
Underwood EL, Thompson LT. High-fat diet impairs spatial memory and hippocampal intrinsic excitability and sex-dependently alters circulating insulin and hippocampal insulin sensitivity. Biol Sex Differ 2016; 7:9. [PMID: 26823968 PMCID: PMC4730722 DOI: 10.1186/s13293-016-0060-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 01/18/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND High-fat diets promoting obesity/type-2 diabetes can impair physiology and cognitive performance, although sex-dependent comparisons of these impairments are rarely made. Transient reductions in Ca(2+)-dependent afterhyperpolarizations (AHPs) occur during memory consolidation, enhancing intrinsic excitability of hippocampal CA1 pyramidal neurons. In rats fed standard diets, insulin can enhance memory and reduce amplitude and duration of AHPs. METHODS Effects of chronic high-fat diet (HFD) on memory, circulating insulin, and neuronal physiology were compared between young adult male and female Long-Evans rats. Rats fed for 12 weeks (from weaning) a HFD or a control diet (CD) were then tested in vivo prior to in vitro recordings from CA1 pyramidal neurons. RESULTS The HFD significantly impaired spatial memory in both males and females. Significant sex differences occurred in circulating insulin and in the insulin sensitivity of hippocampal neurons. Circulating insulin significantly increased in HFD males but decreased in HFD females. While the HFD significantly reduced hippocampal intrinsic excitability in both sexes, CA1 neurons from HFD females remained insulin-sensitive but those from HFD males became insulin-insensitive. CONCLUSIONS Findings consistent with these have been characterized previously in HFD or senescent males, but the effects observed here in young females are unique. Loss of CA1 neuronal excitability, and sex-dependent loss of insulin sensitivity, can have significant cognitive consequences, over both the short term and the life span. These findings highlight needs for more research into sex-dependent differences, relating systemic and neural plasticity mechanisms in metabolic disorders.
Collapse
Affiliation(s)
- Erica L. Underwood
- Cognition & Neuroscience Program, School of Behavioral & Brain Sciences, University of Texas at Dallas, 800 W. Campbell Rd., Richardson, TX 75080 USA
| | - Lucien T. Thompson
- Cognition & Neuroscience Program, School of Behavioral & Brain Sciences, University of Texas at Dallas, 800 W. Campbell Rd., Richardson, TX 75080 USA
| |
Collapse
|
25
|
Increased Basolateral Amygdala Pyramidal Cell Excitability May Contribute to the Anxiogenic Phenotype Induced by Chronic Early-Life Stress. J Neurosci 2015; 35:9730-40. [PMID: 26134655 DOI: 10.1523/jneurosci.0384-15.2015] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
UNLABELLED Adolescence represents a particularly vulnerable period during which exposure to stressors can precipitate the onset of psychiatric disorders and addiction. The basolateral amygdala (BLA) plays an integral role in the pathophysiology of anxiety and addiction. Acute and chronic stress promote increases in BLA pyramidal cell firing, and decreasing BLA excitability alleviates anxiety measures in humans and rodents. Notably, the impact of early-life stress on the mechanisms that govern BLA excitability is unknown. To address this gap in our knowledge, we used a rodent model of chronic early-life stress that engenders robust and enduring increases in anxiety-like behaviors and ethanol intake and examined the impact of this model on the intrinsic excitability of BLA pyramidal cells. Adolescent social isolation was associated with a significant increase in the intrinsic excitability of BLA pyramidal cells and a blunting of the medium component of the afterhyperpolarization potential, a voltage signature of calcium-activated potassium (Kca) channel activity. Western blot analysis revealed reduced expression of small-conductance Kca (SK) channel protein in the BLA of socially isolated (SI) rats. Bath application of a positive SK channel modulator (1-EBIO) normalized firing in ex vivo recordings from SI rats, and in vivo intra-BLA 1-EBIO infusion reduced anxiety-like behaviors. These findings reveal that chronic adolescent stress impairs SK channel function, which contributes to an increase in BLA pyramidal cell excitability and highlights BLA SK channels as promising targets for the treatment of anxiety disorders and comorbid addiction. SIGNIFICANCE STATEMENT Although anxiety disorders and alcohol addiction frequently co-occur, the mechanisms that contribute to this comorbidity are poorly understood. Here, we used a rodent early-life stress model that leads to robust and longlasting increases in behaviors associated with elevated risk of anxiety disorders and addiction to identify novel neurobiological substrates that may underlie these behaviors. Our studies focused on the primary output neurons of the basolateral amygdala, a brain region that plays a key role in anxiety and addiction. We discovered that early-life stress decreases the activity of a specific class of potassium channels and increases the intrinsic excitability of BLA neurons and present evidence that enhancing the function of these channels normalizes BLA excitability and attenuates anxiety-like behaviors.
Collapse
|
26
|
Kruskal PB, Jiang Z, Gao T, Lieber CM. Beyond the patch clamp: nanotechnologies for intracellular recording. Neuron 2015; 86:21-4. [PMID: 25856481 DOI: 10.1016/j.neuron.2015.01.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The patch clamp is a fundamental tool for neuroscientists, offering insights that have shaped our understanding of the brain. Advances in nanotechnology suggest that the next generation of recording methods is now within reach. We discuss the complexity and future promise of applying nanoscience to neural recording.
Collapse
Affiliation(s)
- Peter B Kruskal
- Department of Chemistry and Chemical Biology, and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
| | - Zhe Jiang
- Department of Chemistry and Chemical Biology, and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Teng Gao
- Department of Chemistry and Chemical Biology, and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Charles M Lieber
- Department of Chemistry and Chemical Biology, and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
| |
Collapse
|
27
|
Rau AR, Ariwodola OJ, Weiner JL. Postsynaptic adenosine A2A receptors modulate intrinsic excitability of pyramidal cells in the rat basolateral amygdala. Int J Neuropsychopharmacol 2015; 18:pyv017. [PMID: 25716780 PMCID: PMC4438553 DOI: 10.1093/ijnp/pyv017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The basolateral amygdala plays a critical role in the etiology of anxiety disorders and addiction. Pyramidal neurons, the primary output cells of this region, display increased firing following exposure to stressors, and it is thought that this increase in excitability contributes to stress responsivity and the expression of anxiety-like behaviors. However, much remains unknown about the underlying mechanisms that regulate the intrinsic excitability of basolateral amygdala pyramidal neurons. METHODS Ex vivo gramicidin perforated patch recordings were conducted in current clamp mode where hyper- and depolarizing current steps were applied to basolateral amygdala pyramidal neurons to assess the effects of adenosine A(2A) receptor modulation on intrinsic excitability. RESULTS Activation of adenosine A(2A) receptors with the selective A(2A) receptor agonist CGS-21680 significantly increased the firing rate of basolateral amygdala pyramidal neurons in rat amygdala brain slices, likely via inhibition of the slow afterhyperpolarization potential. Both of these A(2A) receptor-mediated effects were blocked by preapplication of a selective A(2A) receptor antagonist (ZM-241385) or by intra-pipette infusion of a protein kinase A inhibitor, suggesting a postsynaptic locus of A(2A) receptors on basolateral amygdala pyramidal neurons. Interestingly, bath application of the A(2A) receptor antagonist alone significantly attenuated basolateral amygdala pyramidal cell firing, consistent with a role for tonic adenosine in the regulation of the intrinsic excitability of these neurons. CONCLUSIONS Collectively, these data suggest that adenosine, via activation of A(2A) receptors, may directly facilitate basolateral amygdala pyramidal cell output, providing a possible balance for the recently described inhibitory effects of adenosine A1 receptor activation on glutamatergic excitation of basolateral amygdala pyramidal cells.
Collapse
Affiliation(s)
- Andrew R Rau
- Department of Physiology and Pharmacology, School of Medicine (Mr Rau, Mr Ariwodola, and Dr Weiner), Neuroscience Graduate Program, Graduate School of Arts and Sciences (Mr Rau), Wake Forest University, Winston-Salem, North Carolina
| | - Olusegun J Ariwodola
- Department of Physiology and Pharmacology, School of Medicine (Mr Rau, Mr Ariwodola, and Dr Weiner), Neuroscience Graduate Program, Graduate School of Arts and Sciences (Mr Rau), Wake Forest University, Winston-Salem, North Carolina
| | - Jeff L Weiner
- Department of Physiology and Pharmacology, School of Medicine (Mr Rau, Mr Ariwodola, and Dr Weiner), Neuroscience Graduate Program, Graduate School of Arts and Sciences (Mr Rau), Wake Forest University, Winston-Salem, North Carolina.
| |
Collapse
|
28
|
Neuner SM, Wilmott LA, Hope KA, Hoffmann B, Chong JA, Abramowitz J, Birnbaumer L, O'Connell KM, Tryba AK, Greene AS, Savio Chan C, Kaczorowski CC. TRPC3 channels critically regulate hippocampal excitability and contextual fear memory. Behav Brain Res 2015; 281:69-77. [PMID: 25513972 PMCID: PMC4677051 DOI: 10.1016/j.bbr.2014.12.018] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 12/08/2014] [Indexed: 01/02/2023]
Abstract
Memory formation requires de novo protein synthesis, and memory disorders may result from misregulated synthesis of critical proteins that remain largely unidentified. Plasma membrane ion channels and receptors are likely candidates given their role in regulating neuron excitability, a candidate memory mechanism. Here we conduct targeted molecular monitoring and quantitation of hippocampal plasma membrane proteins from mice with intact or impaired contextual fear memory to identify putative candidates. Here we report contextual fear memory deficits correspond to increased Trpc3 gene and protein expression, and demonstrate TRPC3 regulates hippocampal neuron excitability associated with memory function. These data provide a mechanistic explanation for enhanced contextual fear memory reported herein following knockdown of TRPC3 in hippocampus. Collectively, TRPC3 modulates memory and may be a feasible target to enhance memory and treat memory disorders.
Collapse
Affiliation(s)
- Sarah M Neuner
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, United States
| | - Lynda A Wilmott
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, United States
| | - Kevin A Hope
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, United States
| | - Brian Hoffmann
- Department of Biotechnology and Bioengineering, Medical College of Wisconsin, Milwaukee, WI, United States
| | | | - Joel Abramowitz
- Laboratory of Neurobiology, National Institute of Environmental Health Sciences, Research Triangle Park, NC, United States
| | - Lutz Birnbaumer
- Laboratory of Neurobiology, National Institute of Environmental Health Sciences, Research Triangle Park, NC, United States
| | - Kristen M O'Connell
- Department of Physiology, The University of Tennessee Health Science Center, Memphis, TN, United States
| | - Andrew K Tryba
- Department of Pediatrics, The University of Chicago, Chicago, IL, United States
| | - Andrew S Greene
- Department of Biotechnology and Bioengineering, Medical College of Wisconsin, Milwaukee, WI, United States; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - C Savio Chan
- Department of Physiology, Northwestern Fienberg School of Medicine, Chicago, IL, United States
| | - Catherine C Kaczorowski
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, United States.
| |
Collapse
|
29
|
Guan D, Armstrong WE, Foehring RC. Electrophysiological properties of genetically identified subtypes of layer 5 neocortical pyramidal neurons: Ca²⁺ dependence and differential modulation by norepinephrine. J Neurophysiol 2015; 113:2014-32. [PMID: 25568159 DOI: 10.1152/jn.00524.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 01/05/2015] [Indexed: 01/17/2023] Open
Abstract
We studied neocortical pyramidal neurons from two lines of bacterial artificial chromosome mice (etv1 and glt; Gene Expression Nervous System Atlas: GENSAT project), each of which expresses enhanced green fluorescent protein (EGFP) in a different subpopulation of layer 5 pyramidal neurons. In barrel cortex, etv1 and glt pyramidal cells were previously reported to differ in terms of their laminar distribution, morphology, thalamic inputs, cellular targets, and receptive field size. In this study, we measured the laminar distribution of etv1 and glt cells. On average, glt cells were located more deeply; however, the distributions of etv1 and glt cells extensively overlap in layer 5. To test whether these two cell types differed in electrophysiological properties that influence firing behavior, we prepared acute brain slices from 2-4-wk-old mice, where EGFP-positive cells in somatosensory cortex were identified under epifluorescence and then studied using whole cell current- or voltage-clamp recordings. We studied the details of action potential parameters and repetitive firing, characterized by the larger slow afterhyperpolarizations (AHPs) in etv1 neurons and larger medium AHPs (mAHPS) in glt cells, and compared currents underlying the mAHP and slow AHP (sAHP) in etv1 and glt neurons. Etv1 cells exhibited lower dV/dt for spike polarization and repolarization and reduced direct current (DC) gain (lower f-I slope) for repetitive firing than glt cells. Most importantly, we found that 1) differences in the expression of Ca(2+)-dependent K(+) conductances (small-conductance calcium-activated potassium channels and sAHP channels) determine major functional differences between etv1 and glt cells, and 2) there is differential modulation of etv1 and glt neurons by norepinephrine.
Collapse
Affiliation(s)
- Dongxu Guan
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - William E Armstrong
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Robert C Foehring
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee
| |
Collapse
|
30
|
Church TW, Weatherall KL, Corrêa SAL, Prole DL, Brown JT, Marrion NV. Preferential assembly of heteromeric small conductance calcium-activated potassium channels. Eur J Neurosci 2014; 41:305-15. [PMID: 25421315 DOI: 10.1111/ejn.12789] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/16/2014] [Accepted: 10/20/2014] [Indexed: 11/27/2022]
Abstract
The activation of small conductance calcium-dependent (SK) channels regulates membrane excitability by causing membrane hyperpolarization. Three subtypes (SK1-3) have been cloned, with each subtype expressed within the nervous system. The locations of channel subunits overlap, with SK1 and SK2 subunits often expressed in the same brain region. We showed that expressed homomeric rat SK1 subunits did not form functional channels, because subunits accumulated in the Golgi. This raised the question of whether heteromeric channels could form with SK1 subunits. The co-expression of SK1 and SK2 subunits in HEK293 cells preferentially co-assembled to produce heteromeric channels with a fixed stoichiometry of alternating subunits. The expression in hippocampal CA1 neurons of mutant rat SK1 subunits [rat SK1(LV213/4YA)] that produced an apamin-sensitive current changed the amplitude and pharmacology of the medium afterhyperpolarization. The overexpression of rat SK1(LV213/4YA) subunits reduced the sensitivity of the medium afterhyperpolarization to apamin, substantiating the preferential co-assembly of SK1 and SK2 subunits to form heteromeric channels. Species-specific channel assembly occurred as the co-expression of human SK1 with rat SK2 did not form functional heteromeric channels. The replacement of two amino acids within the C-terminus of rat SK2 with those from human SK2 permitted the assembly of heteromeric channels when co-expressed with human SK1. These data showed that species-specific co-assembly was mediated by interaction between the C-termini of SK channel subunits. The finding that SK channels preferentially co-assembled to form heteromeric channels suggested that native heteromeric channels will predominate in cells expressing multiple SK channel subunits.
Collapse
Affiliation(s)
- Timothy W Church
- School of Physiology and Pharmacology, University of Bristol, Bristol, UK
| | | | | | | | | | | |
Collapse
|
31
|
Kv2 channel regulation of action potential repolarization and firing patterns in superior cervical ganglion neurons and hippocampal CA1 pyramidal neurons. J Neurosci 2014; 34:4991-5002. [PMID: 24695716 DOI: 10.1523/jneurosci.1925-13.2014] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Kv2 family "delayed-rectifier" potassium channels are widely expressed in mammalian neurons. Kv2 channels activate relatively slowly and their contribution to action potential repolarization under physiological conditions has been unclear. We explored the function of Kv2 channels using a Kv2-selective blocker, Guangxitoxin-1E (GxTX-1E). Using acutely isolated neurons, mixed voltage-clamp and current-clamp experiments were done at 37°C to study the physiological kinetics of channel gating and action potentials. In both rat superior cervical ganglion (SCG) neurons and mouse hippocampal CA1 pyramidal neurons, 100 nm GxTX-1E produced near-saturating block of a component of current typically constituting ∼60-80% of the total delayed-rectifier current. GxTX-1E also reduced A-type potassium current (IA), but much more weakly. In SCG neurons, 100 nm GxTX-1E broadened spikes and voltage clamp experiments using action potential waveforms showed that Kv2 channels carry ∼55% of the total outward current during action potential repolarization despite activating relatively late in the spike. In CA1 neurons, 100 nm GxTX-1E broadened spikes evoked from -70 mV, but not -80 mV, likely reflecting a greater role of Kv2 when other potassium channels were partially inactivated at -70 mV. In both CA1 and SCG neurons, inhibition of Kv2 channels produced dramatic depolarization of interspike voltages during repetitive firing. In CA1 neurons and some SCG neurons, this was associated with increased initial firing frequency. In all neurons, inhibition of Kv2 channels depressed maintained firing because neurons entered depolarization block more readily. Therefore, Kv2 channels can either decrease or increase neuronal excitability depending on the time scale of excitation.
Collapse
|
32
|
Mateos-Aparicio P, Murphy R, Storm JF. Complementary functions of SK and Kv7/M potassium channels in excitability control and synaptic integration in rat hippocampal dentate granule cells. J Physiol 2013; 592:669-93. [PMID: 24366266 DOI: 10.1113/jphysiol.2013.267872] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The dentate granule cells (DGCs) form the most numerous neuron population of the hippocampal memory system, and its gateway for cortical input. Yet, we have only limited knowledge of the intrinsic membrane properties that shape their responses. Since SK and Kv7/M potassium channels are key mechanisms of neuronal spiking and excitability control, afterhyperpolarizations (AHPs) and synaptic integration, we studied their functions in DGCs. The specific SK channel blockers apamin or scyllatoxin increased spike frequency (excitability), reduced early spike frequency adaptation, fully blocked the medium-duration AHP (mAHP) after a single spike or spike train, and increased postsynaptic EPSP summation after spiking, but had no effect on input resistance (Rinput) or spike threshold. In contrast, blockade of Kv7/M channels by XE991 increased Rinput, lowered the spike threshold, and increased excitability, postsynaptic EPSP summation, and EPSP-spike coupling, but only slightly reduced mAHP after spike trains (and not after single spikes). The SK and Kv7/M channel openers 1-EBIO and retigabine, respectively, had effects opposite to the blockers. Computational modelling reproduced many of these effects. We conclude that SK and Kv7/M channels have complementary roles in DGCs. These mechanisms may be important for the dentate network function, as CA3 neurons can be activated or inhibition recruited depending on DGC firing rate.
Collapse
Affiliation(s)
- Pedro Mateos-Aparicio
- Department of Physiology, IMB, University of Oslo, PB 1104 Blindern, 0317 Oslo, Norway.
| | | | | |
Collapse
|
33
|
Tonini R, Ferraro T, Sampedro-Castañeda M, Cavaccini A, Stocker M, Richards CD, Pedarzani P. Small-conductance Ca2+-activated K+ channels modulate action potential-induced Ca2+ transients in hippocampal neurons. J Neurophysiol 2013; 109:1514-24. [PMID: 23255726 PMCID: PMC3602936 DOI: 10.1152/jn.00346.2012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 12/17/2012] [Indexed: 12/12/2022] Open
Abstract
In hippocampal pyramidal neurons, voltage-gated Ca(2+) channels open in response to action potentials. This results in elevations in the intracellular concentration of Ca(2+) that are maximal in the proximal apical dendrites and decrease rapidly with distance from the soma. The control of these action potential-evoked Ca(2+) elevations is critical for the regulation of hippocampal neuronal activity. As part of Ca(2+) signaling microdomains, small-conductance Ca(2+)-activated K(+) (SK) channels have been shown to modulate the amplitude and duration of intracellular Ca(2+) signals by feedback regulation of synaptically activated Ca(2+) sources in small distal dendrites and dendritic spines, thus affecting synaptic plasticity in the hippocampus. In this study, we investigated the effect of the activation of SK channels on Ca(2+) transients specifically induced by action potentials in the proximal processes of hippocampal pyramidal neurons. Our results, obtained by using selective SK channel blockers and enhancers, show that SK channels act in a feedback loop, in which their activation by Ca(2+) entering mainly through L-type voltage-gated Ca(2+) channels leads to a reduction in the subsequent dendritic influx of Ca(2+). This underscores a new role of SK channels in the proximal apical dendrite of hippocampal pyramidal neurons.
Collapse
Affiliation(s)
- Raffaella Tonini
- Research Dept. of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, UK
| | | | | | | | | | | | | |
Collapse
|
34
|
McKay BM, Oh MM, Galvez R, Burgdorf J, Kroes RA, Weiss C, Adelman JP, Moskal JR, Disterhoft JF. Increasing SK2 channel activity impairs associative learning. J Neurophysiol 2012; 108:863-70. [PMID: 22552186 DOI: 10.1152/jn.00025.2012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Enhanced intrinsic neuronal excitability of hippocampal pyramidal neurons via reductions in the postburst afterhyperpolarization (AHP) has been hypothesized to be a biomarker of successful learning. This is supported by considerable evidence that pharmacologic enhancement of neuronal excitability facilitates learning. However, it has yet to be demonstrated that pharmacologic reduction of neuronal excitability restricted to the hippocampus can retard acquisition of a hippocampus-dependent task. Thus, the present study was designed to address this latter point using a small conductance potassium (SK) channel activator NS309 focally applied to the dorsal hippocampus. SK channels are important contributors to intrinsic excitability, as measured by the medium postburst AHP. NS309 increased the medium AHP and reduced excitatory postsynaptic potential width of CA1 neurons in vitro. In vivo, NS309 reduced the spontaneous firing rate of CA1 pyramidal neurons and impaired trace eyeblink conditioning in rats. Conversely, trace eyeblink conditioning reduced levels of SK2 channel mRNA and protein in the hippocampus. Therefore, the present findings indicate that modulation of SK channels is an important cellular mechanism for associative learning and further support postburst AHP reductions in hippocampal pyramidal neurons as a biomarker of successful learning.
Collapse
Affiliation(s)
- Bridget M McKay
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Zaitsev AV, Povysheva NV, Gonzalez-Burgos G, Lewis DA. Electrophysiological classes of layer 2/3 pyramidal cells in monkey prefrontal cortex. J Neurophysiol 2012; 108:595-609. [PMID: 22496534 DOI: 10.1152/jn.00859.2011] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The activity of supragranular pyramidal neurons in the dorsolateral prefrontal cortex (DLPFC) neurons is hypothesized to be a key contributor to the cellular basis of working memory in primates. Therefore, the intrinsic membrane properties, a crucial determinant of a neuron's functional properties, are important for the role of DLPFC pyramidal neurons in working memory. The present study aimed to investigate the biophysical properties of pyramidal cells in layer 2/3 of monkey DLPFC to create an unbiased electrophysiological classification of these cells. Whole cell voltage recordings in the slice preparation were performed in 77 pyramidal cells, and 24 electrophysiological measures of their passive and active intrinsic membrane properties were analyzed. Based on the results of cluster analysis of 16 independent electrophysiological variables, 4 distinct electrophysiological classes of monkey pyramidal cells were determined. Two classes contain regular-spiking neurons with low and high excitability and constitute 52% of the pyramidal cells sampled. These subclasses of regular-spiking neurons mostly differ in their input resistance, minimum current that evoked firing, and current-to-frequency transduction properties. A third class of pyramidal cells includes low-threshold spiking cells (17%), which fire a burst of three-five spikes followed by regular firing at all suprathreshold current intensities. The last class consists of cells with an intermediate firing pattern (31%). These cells have two modes of firing response, regular spiking and bursting discharge, depending on the strength of stimulation and resting membrane potential. Our results show that diversity in the functional properties of DLPFC pyramidal cells may contribute to heterogeneous modes of information processing during working memory and other cognitive operations that engage the activity of cortical circuits in the superficial layers of the DLPFC.
Collapse
Affiliation(s)
- A V Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, Saint-Petersburg, Russia.
| | | | | | | |
Collapse
|
36
|
Molinari F, Cattani A, Mdzomba J, Aniksztejn L. Glutamate transporters control metabotropic glutamate receptors activation to prevent the genesis of paroxysmal burst in the developing hippocampus. Neuroscience 2012; 207:25-36. [DOI: 10.1016/j.neuroscience.2012.01.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 12/23/2011] [Accepted: 01/19/2012] [Indexed: 12/26/2022]
|
37
|
Kaczorowski CC. Bidirectional pattern-specific plasticity of the slow afterhyperpolarization in rats: role for high-voltage activated Ca2+ channels and I h. Eur J Neurosci 2011; 34:1756-65. [PMID: 22098477 DOI: 10.1111/j.1460-9568.2011.07899.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A burst of action potentials in hippocampal neurons is followed by a slow afterhyperpolarization (sAHP) that serves to limit subsequent firing. A reduction in the sAHP accompanies acquisition of several types of learning, whereas increases in the sAHP are correlated with cognitive impairment. The present study demonstrates in vitro that activity-dependent bidirectional plasticity of the sAHP does not require synaptic activation, and depends on the pattern of action potential firing. Whole-cell current-clamp recordings from CA1 pyramidal neurons in hippocampal slices from young rats (postnatal days 14-24) were performed in blockers of synaptic transmission. The sAHP was evoked by action potential firing at gamma-related (50 Hz, gamma-AHP) or theta frequencies (5 Hz, theta-AHP), two firing frequencies implicated in attention and memory. Interestingly, when the gamma-AHP and theta-AHP were evoked in the same cell, a gradual potentiation of the gamma-AHP (186 ± 31%) was observed that was blocked using Ca(2+) channel blockers nimodipine (10 μm) or ω-conotoxin MVIIC (1 μm). In experiments that exclusively evoked the sAHP with 50 Hz firing, the gamma-AHP was similarly potentiated (198 ± 44%). However, theta-burst firing pattern alone resulted in a decrease (65 ± 19%) of the sAHP. In these experiments, application of the h-channel blocker ZD7288 (25 μm) selectively prevented enhancement of the gamma-AHP. These data demonstrate that induction requirements for bidirectional AHP plasticity depend on the pattern of action potential firing, and result from distinct mechanisms. The identification of novel mechanisms underlying AHP plasticity in vitro provides additional insight into the dynamic processes that may regulate neuronal excitability during learning in vivo.
Collapse
Affiliation(s)
- C C Kaczorowski
- Department of Physiology and Institute for Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
| |
Collapse
|
38
|
Plotkin JL, Day M, Surmeier DJ. Synaptically driven state transitions in distal dendrites of striatal spiny neurons. Nat Neurosci 2011; 14:881-8. [PMID: 21666674 PMCID: PMC3235762 DOI: 10.1038/nn.2848] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 04/06/2011] [Indexed: 12/16/2022]
Abstract
Striatal spiny neurons (SPNs) associate a diverse array of cortically processed information to regulate action selection. But how this is done by SPNs is poorly understood. A key step in this process is the transition of SPNs from a hyperpolarized ‘down-state’ to a sustained, depolarized ‘up-state’. These transitions are thought to reflect a sustained synaptic barrage, involving the coordination of hundreds of pyramidal neurons. Indeed, in mice simulation of cortical input by glutamate uncaging on proximal dendritic spines produced potential changes in SPNs that tracked input time course. However, brief glutamate uncaging at spines on distal dendrites evoked somatic up-states lasting hundreds of milliseconds. These regenerative events depended upon both NMDA receptors and voltage-dependent Ca2+ channels. Moreover, they were bidirectionally regulated by dopamine receptor signaling. This capacity not only changes our model of how up-state are generated in SPNs, it has fundamental implications for the associative process underlying action selection.
Collapse
Affiliation(s)
- Joshua L Plotkin
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | | | | |
Collapse
|
39
|
Gamelli AE, McKinney BC, White JA, Murphy GG. Deletion of the L-type calcium channel Ca(V) 1.3 but not Ca(V) 1.2 results in a diminished sAHP in mouse CA1 pyramidal neurons. Hippocampus 2011; 21:133-41. [PMID: 20014384 DOI: 10.1002/hipo.20728] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Trains of action potentials in CA1 pyramidal neurons are followed by a prolonged calcium-dependent postburst afterhyperpolarization (AHP) that serves to limit further firing to a sustained depolarizing input. A reduction in the AHP accompanies acquisition of several types of learning and increases in the AHP are correlated with age-related cognitive impairment. The AHP develops primarily as the result of activation of outward calcium-activated potassium currents; however, the precise source of calcium for activation of the AHP remains unclear. There is substantial experimental evidence suggesting that calcium influx via voltage-gated L-type calcium channels (L-VGCCs) contributes to the generation of the AHP. Two L-VGCC subtypes are predominately expressed in the hippocampus, Ca(V) 1.2 and Ca(V) 1.3; however, it is not known which L-VGCC subtype is involved in generation of the AHP. This ambiguity is due in large part to the fact that at present there are no subunit-specific agonists or antagonists. Therefore, using mice in which the gene encoding Ca(V) 1.2 or Ca(V) 1.3 was deleted, we sought to determine the impact of alterations in levels of these two L-VCGG subtypes on neuronal excitability. No differences in any AHP measure were seen between neurons from Ca(V) 1.2 knockout mice and controls. However, the total area of the AHP was significantly smaller in neurons from Ca(V) 1.3 knockout mice as compared with neurons from wild-type controls. A significant reduction in the amplitude of the AHP was also seen at the 1 s time point in neurons from Ca(V) 1.3 knockout mice as compared with those from controls. Reductions in both the area and 1 s amplitude suggest the involvement of calcium influx via Ca(V) 1.3 in the slow AHP (sAHP). Thus, the results of our study demonstrate that deletion of Ca(V) 1.3, but not Ca(V) 1.2, significantly impacts the generation of the sAHP.
Collapse
Affiliation(s)
- Amy E Gamelli
- Molecular & Behavioral Neuroscience Institute, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | | | | | | |
Collapse
|
40
|
Sabeti J. Ethanol exposure in early adolescence inhibits intrinsic neuronal plasticity via sigma-1 receptor activation in hippocampal CA1 neurons. Alcohol Clin Exp Res 2011; 35:885-904. [PMID: 21314692 PMCID: PMC3083503 DOI: 10.1111/j.1530-0277.2010.01419.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND We demonstrated previously that rats exposed to chronic intermittent ethanol (CIE) vapors in early adolescence show increased magnitudes of long-term potentiation (LTP) of excitatory transmission when recorded at dendritic synapses in hippocampus. Large amplitude LTP following CIE exposure is mediated by sigma-1 receptors; however, not yet addressed is the role of sigma-1 receptors in modulating the intrinsic properties of neurons to alter their action potential firing during LTP. METHODS Activity-induced plasticity of spike firing was investigated using rat hippocampal slice recordings to measure changes in both field excitatory postsynaptic potentials (fEPSPs) and population spikes (pop. spikes) concomitantly at dendritic inputs and soma of CA1 pyramidal neurons, respectively. RESULTS We observed unique modifications in plasticity of action potential firing in hippocampal slices from CIE exposed adolescent rats, where the induction of large amplitude LTP by 100 Hz stimulations was accompanied by reduced CA1 neuronal excitability--reflected as decreased pop. spike efficacy and impaired activity-induced fEPSP-to-spike (E-S) potentiation. In contrast, LTP induction in ethanol-naïve control slices resulted in increased spike efficacy and robust E-S potentiation. E-S potentiation impairments emerged at 24 hours after CIE treatment cessation, but not before the alcohol withdrawal period, and were restored with bath-application of the sigma-1 receptor selective antagonist BD1047, but not the NMDA receptor antagonist d-AP5. Further evidence revealed a significantly shortened somatic fEPSP time course in adolescent CIE-withdrawn hippocampal slices during LTP; however, paired-pulse data show no apparent correspondence between E-S dissociation and altered recurrent feedback inhibition. CONCLUSIONS Results here suggest that acute withdrawal from adolescent CIE exposure triggers sigma-1 receptors that act to depress the efficacy of excitatory inputs in triggering action potentials during LTP. Such withdrawal-induced depression of E-S plasticity in hippocampus probably entails sigma-1 receptor modulation of 1 or several voltage-gated ion channels controlling the neuronal input-output dynamics.
Collapse
Affiliation(s)
- Jilla Sabeti
- Department of Molecular and Integrative Neurosciences, The Scripps Research Institute, La Jolla, California, USA.
| |
Collapse
|
41
|
Guan D, Horton LR, Armstrong WE, Foehring RC. Postnatal development of A-type and Kv1- and Kv2-mediated potassium channel currents in neocortical pyramidal neurons. J Neurophysiol 2011; 105:2976-88. [PMID: 21451062 DOI: 10.1152/jn.00758.2010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Potassium channels regulate numerous aspects of neuronal excitability, and several voltage-gated K(+) channel subunits have been identified in pyramidal neurons of rat neocortex. Previous studies have either considered the development of outward current as a whole or divided currents into transient, A-type and persistent, delayed rectifier components but did not differentiate between current components defined by α-subunit type. To facilitate comparisons of studies reporting K(+) currents from animals of different ages and to understand the functional roles of specific current components, we characterized the postnatal development of identified Kv channel-mediated currents in pyramidal neurons from layers II/III from rat somatosensory cortex. Both the persistent/slowly inactivating and transient components of the total K(+) current increased in density with postnatal age. We used specific pharmacological agents to test the relative contributions of putative Kv1- and Kv2-mediated currents (100 nM α-dendrotoxin and 600 nM stromatoxin, respectively). A combination of voltage protocol, pharmacology, and curve fitting was used to isolate the rapidly inactivating A-type current. We found that the density of all identified current components increased with postnatal age, approaching a plateau at 3-5 wk. We found no significant changes in the relative proportions or kinetics of any component between postnatal weeks 1 and 5, except that the activation time constant for A-type current was longer at 1 wk. The putative Kv2-mediated component was the largest at all ages. Immunocytochemistry indicated that protein expression for Kv4.2, Kv4.3, Kv1.4, and Kv2.1 increased between 1 wk and 4-5 wk of age.
Collapse
Affiliation(s)
- Dongxu Guan
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | | | | | | |
Collapse
|
42
|
Brown JT, Booth CA, Randall AD. Synaptic activation of mGluR1 generates persistent depression of a fast after-depolarizing potential in CA3 pyramidal neurons. Eur J Neurosci 2011; 33:879-89. [PMID: 21269340 DOI: 10.1111/j.1460-9568.2010.07565.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Burst firing is an important property of hippocampal pyramidal neurons. Group I metabotropic glutamate receptors (mGluRs) produce a multitude of effects on both the synaptic and intrinsic properties of neurons. We investigated whether brief activation of these receptors results in persistent modifications to the intrinsic excitability of rat hippocampal CA3 pyramidal cells (CA3-PCs). In whole-cell current-clamp recordings, current stimuli consisting of filtered, pseudo-random noise produced action potential firing with a mean frequency of ∼1.5-2 Hz. Analysis of spike intervals revealed that this firing included a substantial component (∼20%) of high-frequency (∼100 Hz) bursting activity. Activation of group I mGluRs with (S)-3,5-dihydroxyphenylglycine [(S)-DHPG] selectively eliminated the high-frequency bursts, an effect that persisted > 30 min after (S)-DHPG washout. The fast after-depolarizing potential (ADP) of CA3-PCs is known to be important for generating high-frequency action potential bursting. This ADP was persistently depressed following a short application of (S)-DHPG. This effect was blocked by the mGluR1 antagonist, (S)-(+)-α-amino-4-carboxy-2-methylbenzeneacetic acid (LY367385). In contrast, the depression was resistant to the mGluR5 antagonist 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate, N-methyl-D-aspartate (NMDA) and γ-aminobutyric acid (GABA)(A) antagonists. Unlike other manipulations that generate persistent depression of the ADP in CA3-PCs, DHPG-mediated ADP depression was insensitive to the Kv7 channel inhibitor 10,10-bis(4-Pyridinylmethyl)-9(10H)-anthracenone dihydrochloride (XE991) and strong intracellular Ca(2+) buffering by 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Synaptic activation of mGluRs in the associational-commissural pathway also resulted in persistent depression of the ADP in postsynaptic CA3-PCs, which was blocked by LY367385. These data represent the first evidence that synaptic activation of mGluR1 can modulate the intrinsic excitability properties of hippocampal neurons.
Collapse
Affiliation(s)
- Jon T Brown
- Pfizer Applied Neurophysiology Group, MRC Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | | | | |
Collapse
|
43
|
Park JY, Remy S, Varela J, Cooper DC, Chung S, Kang HW, Lee JH, Spruston N. A post-burst after depolarization is mediated by group i metabotropic glutamate receptor-dependent upregulation of Ca(v)2.3 R-type calcium channels in CA1 pyramidal neurons. PLoS Biol 2010; 8:e1000534. [PMID: 21103408 PMCID: PMC2982802 DOI: 10.1371/journal.pbio.1000534] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 09/21/2010] [Indexed: 12/20/2022] Open
Abstract
The excitability of hippocampal pyramidal neurons is regulated by activation of metabotropic glutamate receptors, an effect that is mediated by modulation of R-type calcium channels. Activation of group I metabotropic glutamate receptors (subtypes mGluR1 and mGluR5) regulates neural activity in a variety of ways. In CA1 pyramidal neurons, activation of group I mGluRs eliminates the post-burst afterhyperpolarization (AHP) and produces an afterdepolarization (ADP) in its place. Here we show that upregulation of Cav2.3 R-type calcium channels is responsible for a component of the ADP lasting several hundred milliseconds. This medium-duration ADP is rapidly and reversibly induced by activation of mGluR5 and requires activation of phospholipase C (PLC) and release of calcium from internal stores. Effects of mGluR activation on subthreshold membrane potential changes are negligible but are large following action potential firing. Furthermore, the medium ADP exhibits a biphasic activity dependence consisting of short-term facilitation and longer-term inhibition. These findings suggest that mGluRs may dramatically alter the firing of CA1 pyramidal neurons via a complex, activity-dependent modulation of Cav2.3 R-type channels that are activated during spiking at physiologically relevant rates and patterns. The hippocampus is an essential structure in the brain for the formation of new declarative memories. Understanding the cellular basis of memory formation, storage, and recall in the hippocampus requires a knowledge of the properties of the relevant neurons and how they are modulated by activity in the neural circuit. For many years, we have known that various chemical neurotransmitters can modulate the electrical excitability of neurons in the hippocampus. Here, we report new experiments to reveal how the chemical neurotransmitter glutamate increases neuronal excitability. The effect we study is the conversion of the afterhyperpolarization (a cellular consequence of firing an action potential) to an afterdepolarization. We identified the metabotropic glutamate receptors involved in this conversion (receptors called mGluR1 and mGluR5) as well as the final target of modulation (R-type calcium channels composed of Cav2.3 subunits), which cause the neurons to exhibit altered excitability in the presence of glutamate. We also determined some of the intermediate steps between activation of the glutamate receptors and modulation of the calcium channels responsible for the change in excitability, offering further mechanistic insight into how synaptic transmission can regulate cellular and network activity.
Collapse
Affiliation(s)
- Jin-Yong Park
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, United States of America
| | - Stefan Remy
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, United States of America
| | - Juan Varela
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, United States of America
| | - Donald C. Cooper
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, United States of America
| | - Sungkwon Chung
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, United States of America
| | - Ho-Won Kang
- Department of Life Science and Basic Science Institute for Cell Damage Control, Sogang University, Seoul, Korea
| | - Jung-Ha Lee
- Department of Life Science and Basic Science Institute for Cell Damage Control, Sogang University, Seoul, Korea
| | - Nelson Spruston
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, United States of America
- * E-mail:
| |
Collapse
|
44
|
Pacemaking in dopaminergic ventral tegmental area neurons: depolarizing drive from background and voltage-dependent sodium conductances. J Neurosci 2010; 30:7401-13. [PMID: 20505107 DOI: 10.1523/jneurosci.0143-10.2010] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Dopaminergic neurons in the ventral tegmental area (VTA) fire spontaneously in a pacemaker-like manner. We analyzed the ionic currents that drive pacemaking in dopaminergic VTA neurons, studied in mouse brain slices. Pacemaking was not inhibited by blocking hyperpolarization-activated cation current (I(h)) or blocking all calcium current by Mg(2+) replacement of Ca(2+). Tetrodotoxin (TTX) stopped spontaneous activity and usually resulted in stable resting potentials near -60 mV to -55 mV, 10-15 mV below the action potential threshold. When external sodium was replaced by N-methyl-D-glucamine (NMDG) with TTX present, cells hyperpolarized by an average of -11 mV, suggesting a significant resting sodium conductance not sensitive to TTX. Voltage-clamp experiments using slow (10 mV/s) ramps showed a steady-state, steeply voltage-dependent current blocked by TTX that activates near -60 mV, as well as a sodium "background" current with little voltage sensitivity, revealed by NMDG replacement for sodium with TTX present. We quantified these two components of sodium current during the pacemaking trajectory using action potential clamp. The initial phase of depolarization, up to approximately -55 mV, is driven mainly by non-voltage-dependent sodium background current. Above -55 mV, TTX-sensitive voltage-dependent "persistent" Na current helps drive the final phase of depolarization to the spike threshold. Voltage-dependent calcium current is small at all subthreshold voltages. The pacemaking mechanism in VTA neurons differs from that in substantia nigra pars compacta (SNc) neurons, where subthreshold calcium current plays a dominant role. In addition, we found that non-voltage-dependent background sodium current is much smaller in SNc neurons than VTA neurons.
Collapse
|
45
|
Mechanisms underlying basal and learning-related intrinsic excitability in a mouse model of Alzheimer's disease. Neurobiol Aging 2009; 32:1452-65. [PMID: 19833411 DOI: 10.1016/j.neurobiolaging.2009.09.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 09/17/2009] [Accepted: 09/18/2009] [Indexed: 11/21/2022]
Abstract
Accumulations of β-amyloid (Aβ) contribute to neurological deficits associated with Alzheimer's disease (AD). The effects of Aβ on basal neuronal excitability and learning-related AHP plasticity were examined using whole-cell recordings from hippocampal neurons in the 5XFAD mouse model of AD. A robust increase in Aβ42 (and elevated levels of Aβ38-40) in naïve 5XFAD mice was associated with decreased basal neuronal excitability, evidenced by a select increase in Ca(2+)-sensitive afterhyperpolarization (AHP). Moreover, trace fear deficits observed in a subset of 5XFAD weak-learner mice were associated with a greater enhancement of the AHP in neurons, as compared to age-matched 5XFAD learner and 5XFAD naïve mice. Importantly, learning-related plasticity of the AHP remained intact in a subset of 5XFAD mice that learned trace fear conditioning to a set criterion. We show that APP-PS1 mutations enhance Aβ and disrupt basal excitability via a Ca(2+)-dependent enhancement of the AHP, and suggest disruption to learning-related modulation of intrinsic excitability resulted, in part, from altered cholinergic modulation of the AHP in the 5XFAD mouse model of AD (170 of 170).
Collapse
|
46
|
McKay BM, Matthews EA, Oliveira FA, Disterhoft JF. Intrinsic neuronal excitability is reversibly altered by a single experience in fear conditioning. J Neurophysiol 2009; 102:2763-70. [PMID: 19726729 DOI: 10.1152/jn.00347.2009] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Learning is known to cause alterations in intrinsic cellular excitability but, to date, these changes have been seen only after multiple training trials. A powerful learning task that can be quickly acquired and extinguished with a single trial is fear conditioning. Rats were trained and extinguished on a hippocampus-dependent form of fear conditioning to determine whether learning-related changes in intrinsic excitability could be observed after a few training trials and a single extinction trial. Following fear training, hippocampal slices were made and intrinsic excitability was assayed via whole cell recordings from CA1 neurons. Alterations in intrinsic excitability, assayed by the postburst afterhyperpolarization and firing frequency accommodation, were observed after only three trials of contextual or trace-cued fear conditioning. Animals that had been trained in contextual and trace-cued fear were then extinguished. Context fear-conditioned animals extinguished in a single trial and the changes in intrinsic excitability were reversed. Trace-cue conditioned animals only partially extinguished in a single trial and reductions in excitability remained. Thus a single learning experience is sufficient to alter intrinsic excitability. This dramatically extends observations of learning-specific changes in intrinsic neuronal excitability previously observed in paradigms requiring many training trials, suggesting the excitability changes have a basic role in acquiring new information.
Collapse
Affiliation(s)
- Bridget M McKay
- Department of Physiology, Northwestern University, Chicago, Illinois, USA.
| | | | | | | |
Collapse
|
47
|
Kaczorowski CC, Disterhoft JF. Memory deficits are associated with impaired ability to modulate neuronal excitability in middle-aged mice. Learn Mem 2009; 16:362-6. [PMID: 19470651 DOI: 10.1101/lm.1365609] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Normal aging disrupts hippocampal neuroplasticity and learning and memory. Aging deficits were exposed in a subset (30%) of middle-aged mice that performed below criterion on a hippocampal-dependent contextual fear conditioning task. Basal neuronal excitability was comparable in middle-aged and young mice, but learning-related modulation of the post-burst afterhyperpolarization (AHP)--a general mechanism engaged during learning--was impaired in CA1 neurons from middle-aged weak learners. Thus, modulation of neuronal excitability is critical for retention of context fear in middle-aged mice. Disruption of AHP plasticity may contribute to contextual fear deficits in middle-aged mice--a model of age-associated cognitive decline (AACD).
Collapse
Affiliation(s)
- Catherine C Kaczorowski
- Northwestern University Interdepartmental Neuroscience Program, Chicago, Illinois 60611, USA.
| | | |
Collapse
|
48
|
Brown JT, Randall AD. Activity-dependent depression of the spike after-depolarization generates long-lasting intrinsic plasticity in hippocampal CA3 pyramidal neurons. J Physiol 2009; 587:1265-81. [PMID: 19171653 DOI: 10.1113/jphysiol.2008.167007] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Persistent plastic changes to the intrinsic excitability of neurons have substantial implications for computational processing within the CNS. We have identified and characterized a novel long-lasting form of intrinsic plasticity in hippocampal CA3 pyramidal cells. Although the patterns of action potential firing elicited in this cell population by depolarizing current injections exhibited considerable diversity, practically all cells produced an initial high frequency (>100 Hz) burst of two to five spikes. This burst involved conductances that were responsible for the prominent spike afterdepolarization of CA3 pyramids. Long-lasting changes in the firing behaviour of CA3 cells were produced by conditioning stimuli (CS) consisting of either periods of depolarization in voltage clamp or periods of short (2 or 4 spikes) high frequency (circa 100 Hz) burst firing at 5 or 10 Hz. CS-induced changes included substantial prolongation of the first inter-spike interval and increased spike jitter. Similar CS-induced changes were seen when the test stimulus used to elicit firing resembled a glutamatergic EPSC. In line with this, a long-lasting depression of the ADP was elicited by the same CS that altered firing patterns of CA3 cells. Conditioning-induced changes in both spiking patterns and ADP amplitude were blocked by buffering intracellular Ca(2+) with BAPTA. Furthermore, the Kv7 channel blocker XE991, a cognitive enhancer, both enhanced the ADP and completely eliminated its conditioning-induced depression. These findings indicate that a persistent enhancement of Kv7 channels, following a transient increase in cytoplasmic Ca(2+), results in a prolonged depression of the ADP in CA3 pyramidal neurones.
Collapse
Affiliation(s)
- Jon T Brown
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, University Walk, Bristol BS8 1TD, UK.
| | | |
Collapse
|
49
|
Learning-related postburst afterhyperpolarization reduction in CA1 pyramidal neurons is mediated by protein kinase A. Proc Natl Acad Sci U S A 2009; 106:1620-5. [PMID: 19164584 DOI: 10.1073/pnas.0807708106] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Learning-related reductions of the postburst afterhyperpolarization (AHP) in hippocampal pyramidal neurons have been shown ex vivo, after trace eyeblink conditioning. The AHP is also reduced by many neuromodulators, such as norepinephrine, via activation of protein kinases. Trace eyeblink conditioning, like other hippocampus-dependent tasks, relies on protein synthesis for consolidating the learned memory. Protein kinase A (PKA) has been shown to be a key contributor for protein synthesis via the cAMP-response element-binding pathway. Here, we have explored a potential involvement of PKA and protein kinase C (PKC) in maintaining the learning-related postburst AHP reduction observed in CA1 pyramidal neurons. Bath application of isoproterenol (1 muM), a beta-adrenergic agonist that activates PKA, significantly reduced the AHP in CA1 neurons from control animals, but not from rats that learned. This occlusion suggests that PKA activity is involved in maintaining the AHP reduction measured ex vivo after successful learning. In contrast, bath application of the PKC activator, (-) indolactam V (0.2 muM), significantly reduced the AHP in CA1 neurons from both control and trained rats, indicating that PKC activity is not involved in maintaining the AHP reduction at this point after learning.
Collapse
|
50
|
Region-specific spike-frequency acceleration in layer 5 pyramidal neurons mediated by Kv1 subunits. J Neurosci 2009; 28:13716-26. [PMID: 19091962 DOI: 10.1523/jneurosci.2940-08.2008] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Separation of the cortical sheet into functionally distinct regions is a hallmark of neocortical organization. Cortical circuit function emerges from afferent and efferent connectivity, local connectivity within the cortical microcircuit, and the intrinsic membrane properties of neurons that comprise the circuit. While localization of functions to particular cortical areas can be partially accounted for by regional differences in both long range and local connectivity, it is unknown whether the intrinsic membrane properties of cortical cell types differ between cortical regions. Here we report the first example of a region-specific firing type in layer 5 pyramidal neurons, and show that the intrinsic membrane and integrative properties of a discrete subtype of layer 5 pyramidal neurons differ between primary motor and somatosensory cortices due to region- and cell-type-specific Kv1 subunit expression.
Collapse
|