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Tiroshi L, Atamna Y, Gilin N, Berkowitz N, Goldberg JA. Striatal Neurons Are Recruited Dynamically into Collective Representations of Self-Initiated and Learned Actions in Freely Moving Mice. eNeuro 2024; 11:ENEURO.0315-23.2023. [PMID: 38164559 PMCID: PMC11057506 DOI: 10.1523/eneuro.0315-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 11/05/2023] [Accepted: 11/17/2023] [Indexed: 01/03/2024] Open
Abstract
Striatal spiny projection neurons are hyperpolarized-at-rest (HaR) and driven to action potential threshold by a small number of powerful inputs-an input-output configuration that is detrimental to response reliability. Because the striatum is important for habitual behaviors and goal-directed learning, we conducted a microendoscopic imaging in freely moving mice that express a genetically encoded Ca2+ indicator sparsely in striatal HaR neurons to evaluate their response reliability during self-initiated movements and operant conditioning. The sparse expression was critical for longitudinal studies of response reliability, and for studying correlations among HaR neurons while minimizing spurious correlations arising from contamination by the background signal. We found that HaR neurons are recruited dynamically into action representation, with distinct neuronal subsets being engaged in a moment-by-moment fashion. While individual neurons respond with little reliability, the population response remained stable across days. Moreover, we found evidence for the temporal coupling between neuronal subsets during conditioned (but not innate) behaviors.
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Affiliation(s)
- Lior Tiroshi
- Department of Medical Neurobiology, Institute of Medical Research Israel - Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102, Jerusalem, Israel
| | - Yara Atamna
- Department of Medical Neurobiology, Institute of Medical Research Israel - Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102, Jerusalem, Israel
| | - Naomi Gilin
- Department of Medical Neurobiology, Institute of Medical Research Israel - Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102, Jerusalem, Israel
| | - Noa Berkowitz
- Department of Medical Neurobiology, Institute of Medical Research Israel - Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102, Jerusalem, Israel
| | - Joshua A Goldberg
- Department of Medical Neurobiology, Institute of Medical Research Israel - Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, 9112102, Jerusalem, Israel
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Di Bisceglie Caballero S, Ces A, Liberge M, Ambroggi F, Amalric M, Ouagazzal AM. Optogenetic Globus Pallidus Stimulation Improves Motor Deficits in 6-Hydroxydopamine-Lesioned Mouse Model of Parkinson's Disease. Int J Mol Sci 2023; 24:ijms24097935. [PMID: 37175643 PMCID: PMC10178372 DOI: 10.3390/ijms24097935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/31/2023] [Accepted: 04/24/2023] [Indexed: 05/15/2023] Open
Abstract
Excessive inhibition of the external globus pallidus (GPe) by striatal GABAergic neurons is considered a central mechanism contributing to motor symptoms of Parkinson's disease (PD). While electrophysiological findings support this view, behavioral studies assessing the beneficial effects of global GPe activations are scarce and the reported results are controversial. We used an optogenetic approach and the standard unilateral 6-hydroxydopamine nigrostriatal dopamine (DA) lesion model of PD to explore the effects of GPe photostimulation on motor deficits in mice. Global optogenetic GPe inhibition was used in normal mice to verify whether it reproduced the typical motor impairment induced by DA lesions. GPe activation improved ipsilateral circling, contralateral forelimb akinesia, locomotor hypoactivity, and bradykinesia in 6-OHDA-lesioned mice at ineffective photostimulation parameters (532 nm, 5 Hz, 3 mW) in normal mice. GPe photoinhibition (450 nm, 12 mW) had no effect on locomotor activity and forelimb use in normal mice. Bilateral photoinhibition (450 nm, 6 mW/side) reduced directed exploration and improved working memory performances indicating that recruitment of GPe in physiological conditions may depend on the behavioral task involved. Collectively, these findings shed new light on the functional role of GPe and suggest that it is a promising target for neuromodulatory restoration of motor deficits in PD.
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Affiliation(s)
| | - Aurelia Ces
- Aix-Marseille Université, CNRS, LNC (UMR 729), 13331 Marseille, France
| | - Martine Liberge
- Aix-Marseille Université, CNRS, LNC (UMR 729), 13331 Marseille, France
| | - Frederic Ambroggi
- Aix-Marseille Université, CNRS, LNC (UMR 729), 13331 Marseille, France
| | - Marianne Amalric
- Aix-Marseille Université, CNRS, LNC (UMR 729), 13331 Marseille, France
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3
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Abstract
In 1959, E. G. Gray described two different types of synapses in the brain for the first time: symmetric and asymmetric. Later on, symmetric synapses were associated with inhibitory terminals, and asymmetric synapses to excitatory signaling. The balance between these two systems is critical to maintain a correct brain function. Likewise, the modulation of both types of synapses is also important to maintain a healthy equilibrium. Cerebral circuitry responds differently depending on the type of damage and the timeline of the injury. For example, promoting symmetric signaling following ischemic damage is beneficial only during the acute phase; afterwards, it further increases the initial damage. Synapses can be also altered by players not directly related to them; the chronic and long-term neurodegeneration mediated by tau proteins primarily targets asymmetric synapses by decreasing neuronal plasticity and functionality. Dopamine represents the main modulating system within the central nervous system. Indeed, the death of midbrain dopaminergic neurons impairs locomotion, underlying the devastating Parkinson’s disease. Herein, we will review studies on symmetric and asymmetric synapses plasticity after three different stressors: symmetric signaling under acute damage—ischemic stroke; asymmetric signaling under chronic and long-term neurodegeneration—Alzheimer’s disease; symmetric and asymmetric synapses without modulation—Parkinson’s disease.
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Sciamanna G, Ponterio G, Vanni V, Laricchiuta D, Martella G, Bonsi P, Meringolo M, Tassone A, Mercuri NB, Pisani A. Optogenetic Activation of Striatopallidal Neurons Reveals Altered HCN Gating in DYT1 Dystonia. Cell Rep 2021; 31:107644. [PMID: 32433955 DOI: 10.1016/j.celrep.2020.107644] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 12/10/2019] [Accepted: 04/20/2020] [Indexed: 12/30/2022] Open
Abstract
Firing activity of external globus pallidus (GPe) is crucial for motor control and is severely perturbed in dystonia, a movement disorder characterized by involuntary, repetitive muscle contractions. Here, we show that GPe projection neurons exhibit a reduction of firing frequency and an irregular pattern in a DYT1 dystonia model. Optogenetic activation of the striatopallidal pathway fails to reset pacemaking activity of GPe neurons in mutant mice. Abnormal firing is paralleled by alterations in motor learning. We find that loss of dopamine D2 receptor-dependent inhibition causes increased GABA input at striatopallidal synapses, with subsequent downregulation of hyperpolarization-activated, cyclic nucleotide-gated cation (HCN) channels. Accordingly, enhancing in vivo HCN channel activity or blocking GABA release restores both the ability of striatopallidal inputs to pause ongoing GPe activity and motor coordination deficits. Our findings demonstrate an impaired striatopallidal connectivity, supporting the central role of GPe in motor control and, more importantly, identifying potential pharmacological targets for dystonia.
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Affiliation(s)
- Giuseppe Sciamanna
- Department of Systems Medicine, University of Rome "Tor Vergata," Rome, Italy; Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Giulia Ponterio
- Department of Systems Medicine, University of Rome "Tor Vergata," Rome, Italy
| | - Valentina Vanni
- Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Daniela Laricchiuta
- Department of Psychology, Faculty of Medicine and Psychology, University of Rome Sapienza, Rome, Italy; Lab of Behavioural and Experimental Neurophysiology, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Giuseppina Martella
- Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Paola Bonsi
- Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Maria Meringolo
- Department of Systems Medicine, University of Rome "Tor Vergata," Rome, Italy
| | - Annalisa Tassone
- Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Nicola Biagio Mercuri
- Department of Systems Medicine, University of Rome "Tor Vergata," Rome, Italy; Lab of Experimental Neurology, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Antonio Pisani
- Department of Systems Medicine, University of Rome "Tor Vergata," Rome, Italy; Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy.
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5
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Phillips RS, Rosner I, Gittis AH, Rubin JE. The effects of chloride dynamics on substantia nigra pars reticulata responses to pallidal and striatal inputs. eLife 2020; 9:e55592. [PMID: 32894224 PMCID: PMC7476764 DOI: 10.7554/elife.55592] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 08/14/2020] [Indexed: 11/20/2022] Open
Abstract
As a rodent basal ganglia (BG) output nucleus, the substantia nigra pars reticulata (SNr) is well positioned to impact behavior. SNr neurons receive GABAergic inputs from the striatum (direct pathway) and globus pallidus (GPe, indirect pathway). Dominant theories of action selection rely on these pathways' inhibitory actions. Yet, experimental results on SNr responses to these inputs are limited and include excitatory effects. Our study combines experimental and computational work to characterize, explain, and make predictions about these pathways. We observe diverse SNr responses to stimulation of SNr-projecting striatal and GPe neurons, including biphasic and excitatory effects, which our modeling shows can be explained by intracellular chloride processing. Our work predicts that ongoing GPe activity could tune the SNr operating mode, including its responses in decision-making scenarios, and GPe output may modulate synchrony and low-frequency oscillations of SNr neurons, which we confirm using optogenetic stimulation of GPe terminals within the SNr.
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Affiliation(s)
- Ryan S Phillips
- Department of Mathematics, University of PittsburghPittsburghUnited States
- Center for the Neural Basis of CognitionPittsburghUnited States
| | - Ian Rosner
- Center for the Neural Basis of CognitionPittsburghUnited States
- Department of Biological Sciences, Carnegie Mellon UniversityPittsburghUnited States
| | - Aryn H Gittis
- Center for the Neural Basis of CognitionPittsburghUnited States
- Department of Biological Sciences, Carnegie Mellon UniversityPittsburghUnited States
| | - Jonathan E Rubin
- Department of Mathematics, University of PittsburghPittsburghUnited States
- Center for the Neural Basis of CognitionPittsburghUnited States
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Maizey L, Evans CJ, Muhlert N, Verbruggen F, Chambers CD, Allen CPG. Cortical and subcortical functional specificity associated with response inhibition. Neuroimage 2020; 220:117110. [PMID: 32619711 PMCID: PMC7573537 DOI: 10.1016/j.neuroimage.2020.117110] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 05/18/2020] [Accepted: 06/26/2020] [Indexed: 01/23/2023] Open
Abstract
Is motor response inhibition supported by a specialised neuronal inhibitory control mechanism, or by a more general system of action updating? This pre-registered study employed a context-cueing paradigm requiring both inhibitory and non-inhibitory action updating in combination with functional magnetic resonance imaging to test the specificity of responses under different updating conditions, including the cancellation of actions. Cortical regions of activity were found to be common to multiple forms of action updating. However, functional specificity during response inhibition was observed in the anterior right inferior frontal gyrus. In addition, fronto-subcortical activity was explored using a novel contrast method. These exploratory results indicate that the specificity for response inhibition observed in right prefrontal cortex continued downstream and was observed in right hemisphere subcortical activity, while left hemisphere activity was associated with right-hand response execution. Overall, our findings reveal both common and distinct correlates of response inhibition in prefrontal cortex, with exploratory analyses supporting putative models of subcortical pathways and extending them through the demonstration of lateralisation.
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Affiliation(s)
- Leah Maizey
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, United Kingdom.
| | - C John Evans
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, United Kingdom
| | - Nils Muhlert
- Division of Neuroscience and Experimental Psychology, University of Manchester, United Kingdom
| | | | - Christopher D Chambers
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, United Kingdom
| | - Christopher P G Allen
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, United Kingdom.
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7
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Cellular and Synaptic Dysfunctions in Parkinson's Disease: Stepping out of the Striatum. Cells 2019; 8:cells8091005. [PMID: 31470672 PMCID: PMC6769933 DOI: 10.3390/cells8091005] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 08/28/2019] [Accepted: 08/29/2019] [Indexed: 12/30/2022] Open
Abstract
The basal ganglia (BG) are a collection of interconnected subcortical nuclei that participate in a great variety of functions, ranging from motor programming and execution to procedural learning, cognition, and emotions. This network is also the region primarily affected by the degeneration of midbrain dopaminergic neurons localized in the substantia nigra pars compacta (SNc). This degeneration causes cellular and synaptic dysfunctions in the BG network, which are responsible for the appearance of the motor symptoms of Parkinson’s disease. Dopamine (DA) modulation and the consequences of its loss on the striatal microcircuit have been extensively studied, and because of the discrete nature of DA innervation of other BG nuclei, its action outside the striatum has been considered negligible. However, there is a growing body of evidence supporting functional extrastriatal DA modulation of both cellular excitability and synaptic transmission. In this review, the functional relevance of DA modulation outside the striatum in both normal and pathological conditions will be discussed.
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Morales-Figueroa GE, Rivera-Ramírez N, González-Pantoja R, Escamilla-Sánchez J, García-Hernández U, Galván EJ, Arias-Montaño JA. Adenosine A 2A and histamine H 3 receptors interact at the cAMP/PKA pathway to modulate depolarization-evoked [ 3H]-GABA release from rat striato-pallidal terminals. Purinergic Signal 2018; 15:85-93. [PMID: 30565027 DOI: 10.1007/s11302-018-9638-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 11/20/2018] [Indexed: 02/06/2023] Open
Abstract
We previously reported that the activation of histamine H3 receptors (H3Rs) selectively counteracts the facilitatory action of adenosine A2A receptors (A2ARs) on GABA release from rat globus pallidus (GP) isolated nerve terminals (synaptosomes). In this work, we examined the mechanisms likely to underlie this functional interaction. Three possibilities were explored: (a) changes in receptor affinity for agonists induced by physical A2AR/H3R interaction, (b) opposite actions of A2ARs and H3Rs on depolarization-induced Ca2+ entry, and (c) an A2AR/H3R interaction at the level of adenosine 3',5'-cyclic monophosphate (cAMP) formation. In GP synaptosomal membranes, H3R activation with immepip reduced A2AR affinity for the agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride hydrate (CGS-21680) (Ki control 4.53 nM; + immepip 9.32 nM), whereas A2AR activation increased H3R affinity for immepip (Ki control 0.63 nM; + CGS-21680 0.26 nM). Neither A2AR activation nor H3R stimulation modified calcium entry through voltage-gated calcium channels in GP synaptosomes, as evaluated by microfluorometry. A2AR-mediated facilitation of depolarization-evoked [2,3-3H]-γ-aminobutyric acid ([3H]-GABA) release from GP synaptosomes (130.4 ± 3.6% of control values) was prevented by the PKA inhibitor H-89 and mimicked by the adenylyl cyclase activator forskolin or by 8-Bromo-cAMP, a membrane permeant cAMP analogue (169.5 ± 17.3 and 149.5 ± 14.5% of controls). H3R activation failed to reduce the facilitation of [3H]-GABA release induced by 8-Bromo-cAMP. In GP slices, A2AR activation stimulated cAMP accumulation (290% of basal) and this effect was reduced (- 75%) by H3R activation. These results indicate that in striato-pallidal nerve terminals, A2ARs and H3Rs interact at the level of cAMP formation to modulate PKA activity and thus GABA release.
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Affiliation(s)
- Guadalupe-Elide Morales-Figueroa
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Nayeli Rivera-Ramírez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Raúl González-Pantoja
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Juan Escamilla-Sánchez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Ubaldo García-Hernández
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México
| | - Emilio J Galván
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, 07360, MÉXICO, México
| | - José-Antonio Arias-Montaño
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, AV. IPN 2508, Ciudad de México, México.
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9
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Coffey KR, Nader M, Bawa J, West MO. Homogeneous processing in the striatal direct and indirect pathways: single body part sensitive type IIb neurons may express either dopamine receptor D1 or D2. Eur J Neurosci 2017; 46:2380-2391. [PMID: 28887882 DOI: 10.1111/ejn.13690] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 08/25/2017] [Accepted: 08/29/2017] [Indexed: 11/28/2022]
Abstract
Striatal medium spiny projection neurons (MSNs) output through two diverging circuits, the 'direct and indirect pathways' which originate from minimally overlapping populations of MSNs expressing either the dopamine receptor D1 or the dopamine receptor D2. One modern theory of direct and indirect pathway function proposes that activation of direct pathway MSNs facilitates output of desired motor programs, while activation of indirect pathway MSNs inhibits competing motor programs. A separate theory suggests that coordinated timing or synchrony of the direct and indirect pathways is critical for the execution of refined movements. These hypotheses are made testable by a common type of striatal neuron known as type IIb MSNs. Clusters of these MSNs exhibit phasic increases in firing rate related to sensorimotor activity of single body parts. If these MSNs were to reside in only the direct pathway, evidence would be provided that D1 MSNs are 'motor program' specific, which would lend credence to the 'competing motor programs' hypothesis. However, if type IIb MSNs reside in both pathways, evidence would be provided for the 'coordinated timing or synchrony' hypothesis. Our results show that type IIb neurons may express either D1 or D2. This evidence supports the theory that the coordinated timing or synchrony of the direct and indirect pathways is critical for refined movements. We also propose a model in which the direct and indirect pathways act as a differentiator circuit, providing a possible mechanism by which coordinated activity of D1 and D2 neurons may output meaningful somatosensorimotor information to downstream structures.
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Affiliation(s)
- Kevin R Coffey
- Department of Psychology, Rutgers University, 152 Frelinghuysen Road, Piscataway, NJ, 08854, USA.,Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, 98104, USA
| | - Miles Nader
- Department of Psychology, Rutgers University, 152 Frelinghuysen Road, Piscataway, NJ, 08854, USA
| | - Jasmeet Bawa
- Department of Psychology, Rutgers University, 152 Frelinghuysen Road, Piscataway, NJ, 08854, USA
| | - Mark O West
- Department of Psychology, Rutgers University, 152 Frelinghuysen Road, Piscataway, NJ, 08854, USA
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10
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Barbera G, Liang B, Zhang L, Gerfen CR, Culurciello E, Chen R, Li Y, Lin DT. Spatially Compact Neural Clusters in the Dorsal Striatum Encode Locomotion Relevant Information. Neuron 2016; 92:202-213. [PMID: 27667003 DOI: 10.1016/j.neuron.2016.08.037] [Citation(s) in RCA: 187] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 07/20/2016] [Accepted: 08/24/2016] [Indexed: 11/19/2022]
Abstract
An influential striatal model postulates that neural activities in the striatal direct and indirect pathways promote and inhibit movement, respectively. Normal behavior requires coordinated activity in the direct pathway to facilitate intended locomotion and indirect pathway to inhibit unwanted locomotion. In this striatal model, neuronal population activity is assumed to encode locomotion relevant information. Here, we propose a novel encoding mechanism for the dorsal striatum. We identified spatially compact neural clusters in both the direct and indirect pathways. Detailed characterization revealed similar cluster organization between the direct and indirect pathways, and cluster activities from both pathways were correlated with mouse locomotion velocities. Using machine-learning algorithms, cluster activities could be used to decode locomotion relevant behavioral states and locomotion velocity. We propose that neural clusters in the dorsal striatum encode locomotion relevant information and that coordinated activities of direct and indirect pathway neural clusters are required for normal striatal controlled behavior. VIDEO ABSTRACT.
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Affiliation(s)
- Giovanni Barbera
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 333 Cassell Drive, Baltimore, MD 21224, USA; Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Drive, West Lafayette, IN 47907, USA
| | - Bo Liang
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 333 Cassell Drive, Baltimore, MD 21224, USA
| | - Lifeng Zhang
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 333 Cassell Drive, Baltimore, MD 21224, USA
| | - Charles R Gerfen
- Intramural Research Program, National Institute of Mental Health, National Institutes of Health, Building 49, Room 5A60, Bethesda, MD 20814, USA
| | - Eugenio Culurciello
- Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Drive, West Lafayette, IN 47907, USA
| | - Rong Chen
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 100 N Greene St, Baltimore, MD 21201, USA.
| | - Yun Li
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 333 Cassell Drive, Baltimore, MD 21224, USA.
| | - Da-Ting Lin
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 333 Cassell Drive, Baltimore, MD 21224, USA; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA.
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11
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Hernández-Martínez R, Aceves JJ, Rueda-Orozco PE, Hernández-Flores T, Hernández-González O, Tapia D, Galarraga E, Bargas J. Muscarinic presynaptic modulation in GABAergic pallidal synapses of the rat. J Neurophysiol 2015; 113:796-807. [DOI: 10.1152/jn.00385.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The external globus pallidus (GPe) is central for basal ganglia processing. It expresses muscarinic cholinergic receptors and receives cholinergic afferents from the pedunculopontine nuclei (PPN) and other regions. The role of these receptors and afferents is unknown. Muscarinic M1-type receptors are expressed by synapses from striatal projection neurons (SPNs). Because axons from SPNs project to the GPe, one hypothesis is that striatopallidal GABAergic terminals may be modulated by M1 receptors. Alternatively, some M1 receptors may be postsynaptic in some pallidal neurons. Evidence of muscarinic modulation in any of these elements would suggest that cholinergic afferents from the PPN, or other sources, could modulate the function of the GPe. In this study, we show this evidence using striatopallidal slice preparations: after field stimulation in the striatum, the cholinergic muscarinic receptor agonist muscarine significantly reduced the amplitude of inhibitory postsynaptic currents (IPSCs) from synapses that exhibited short-term synaptic facilitation. This inhibition was associated with significant increases in paired-pulse facilitation, and quantal content was proportional to IPSC amplitude. These actions were blocked by atropine, pirenzepine, and mamba toxin-7, suggesting that receptors involved were M1. In addition, we found that some pallidal neurons have functional postsynaptic M1 receptors. Moreover, some evoked IPSCs exhibited short-term depression and a different kind of modulation: they were indirectly modulated by muscarine via the activation of presynaptic cannabinoid CB1 receptors. Thus pallidal synapses presenting distinct forms of short-term plasticity were modulated differently.
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Affiliation(s)
- Ricardo Hernández-Martínez
- Instituto de Fisiología Celular, División de Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - José J. Aceves
- Instituto de Fisiología Celular, División de Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Pavel E. Rueda-Orozco
- Instituto de Fisiología Celular, División de Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Teresa Hernández-Flores
- Instituto de Fisiología Celular, División de Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Omar Hernández-González
- Instituto de Fisiología Celular, División de Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Dagoberto Tapia
- Instituto de Fisiología Celular, División de Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Elvira Galarraga
- Instituto de Fisiología Celular, División de Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - José Bargas
- Instituto de Fisiología Celular, División de Neurociencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
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12
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Yoshida A, Tanaka M. Two Types of Neurons in the Primate Globus Pallidus External Segment Play Distinct Roles in Antisaccade Generation. Cereb Cortex 2015; 26:1187-99. [PMID: 25577577 DOI: 10.1093/cercor/bhu308] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The globus pallidus external segment (GPe) constitutes part of the indirect pathway of the basal ganglia. Because of inhibitory projections from the striatum, most GPe neurons are expected to reduce activity during movements. However, many GPe neurons in fact display increased activity. We previously found that both excitatory and inhibitory responses were modulated during antisaccades, when eyes were directed away from a visual stimulus. To elucidate the roles of these neurons during antisaccades, we examined neuronal activities as monkeys performed antisaccades, prosaccades, and NoGo tasks under 2 conditions. In the Deliberate condition, the task-rule was instructed by color of the fixation point, while in the Immediate condition, it was given by color of the target. Under both conditions, the increase-type neurons exhibited greater activity during antisaccades compared with the other tasks and neuronal activity negatively correlated with saccade latency. The decrease-type neurons also showed greater modulation during antisaccades but their activity was comparable between NoGo and antisaccade trials in the Immediate condition. These results suggest that the increase-type neurons might play a role in facilitating antisaccades, whereas the decrease-type neurons could mediate signals for reflexive saccade suppression. We propose that these GPe neurons are differently involved in basal ganglia pathways.
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Affiliation(s)
- Atsushi Yoshida
- Department of Physiology Department of Diagnostic and Interventional Radiology, Hokkaido University School of Medicine, Sapporo 060-8638, Japan
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13
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Sommer WH, Costa RM, Hansson AC. Dopamine systems adaptation during acquisition and consolidation of a skill. Front Integr Neurosci 2014; 8:87. [PMID: 25414648 PMCID: PMC4220658 DOI: 10.3389/fnint.2014.00087] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 10/16/2014] [Indexed: 11/13/2022] Open
Abstract
The striatum plays a key role in motor learning. Striatal function depends strongly on dopaminergic neurotransmission, but little is known about neuroadaptions of the dopamine system during striatal learning. Using an established task that allows differentiation between acquisition and consolidation of motor learning, we here investigate D1 and D2-like receptor binding and transcriptional levels after initial and long-term training of mice. We found profound reduction in D1 binding within the dorsomedial striatum (DMS) after the first training session on the accelerated rotarod and a progressive reduction in D2-like binding within the dorsolateral striatum (DLS) after extended training. Given that similar phase- and region-specific striatal neuroadaptations have been found also during learning of complex procedural tasks including habit formation and automatic responding, the here observed neurochemical alterations are important for our understanding of neuropsychiatric disorders that show a dysbalance in the function of striatal circuits, such as in addictive behaviors.
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Affiliation(s)
- Wolfgang H Sommer
- Institute of Psychopharmacology at Central Institute of Mental Health, University of Heidelberg Mannheim, Germany ; Department of Addiction Medicine at Central Institute of Mental Health, University of Heidelberg Mannheim, Germany
| | - Rui M Costa
- Champalimaud Neuroscience Programme, Champalimaud Center for the Unknown Lisbon, Portugal
| | - Anita C Hansson
- Institute of Psychopharmacology at Central Institute of Mental Health, University of Heidelberg Mannheim, Germany
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14
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Morales-Figueroa GE, Márquez-Gómez R, González-Pantoja R, Escamilla-Sánchez J, Arias-Montaño JA. Histamine H3 receptor activation counteracts adenosine A2A receptor-mediated enhancement of depolarization-evoked [3H]-GABA release from rat globus pallidus synaptosomes. ACS Chem Neurosci 2014; 5:637-45. [PMID: 24884070 DOI: 10.1021/cn500001m] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
High levels of histamine H3 receptors (H3Rs) are found in the globus pallidus (GP), a neuronal nucleus in the basal ganglia involved in the control of motor behavior. By using rat GP isolated nerve terminals (synaptosomes), we studied whether H3R activation modified the previously reported enhancing action of adenosine A2A receptor (A2AR) stimulation on depolarization-evoked [(3)H]-GABA release. At 3 and 10 nM, the A2AR agonist CGS-21680 enhanced [(3)H]-GABA release induced by high K(+) (20 mM) and the effect of 3 nM CGS-21680 was prevented by the A2AR antagonist ZM-241385 (100 nM). The presence of presynaptic H3Rs was confirmed by the specific binding of N-α-[methyl-(3)H]-histamine to membranes from GP synaptosomes (maximum binding, Bmax, 1327 ± 79 fmol/mg protein; dissociation constant, Kd, 0.74 nM), which was inhibited by the H3R ligands immepip, clobenpropit, and A-331440 (inhibition constants, Ki, 0.28, 8.53, and 316 nM, respectively). Perfusion of synaptosomes with the H3R agonist immepip (100 nM) had no effect on K(+)-evoked [(3)H]-GABA release, but inhibited the stimulatory action of A2AR activation. In turn, the effect of immepip was blocked by the H3R antagonist clobenpropit, which had no significant effect of its own on K(+)-induced [(3)H]-GABA release. These data indicate that H3R activation selectively counteracts the facilitatory action of A2AR stimulation on GABA release from striato-pallidal projections.
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Affiliation(s)
- Guadalupe-Elide Morales-Figueroa
- Departamento de Fisiología,
Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico
Nacional 2508, Zacatenco, 07360 México, D.F., México
| | - Ricardo Márquez-Gómez
- Departamento de Fisiología,
Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico
Nacional 2508, Zacatenco, 07360 México, D.F., México
| | - Raúl González-Pantoja
- Departamento de Fisiología,
Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico
Nacional 2508, Zacatenco, 07360 México, D.F., México
| | - Juan Escamilla-Sánchez
- Departamento de Fisiología,
Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico
Nacional 2508, Zacatenco, 07360 México, D.F., México
| | - José-Antonio Arias-Montaño
- Departamento de Fisiología,
Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico
Nacional 2508, Zacatenco, 07360 México, D.F., México
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15
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Concurrent activation of striatal direct and indirect pathways during action initiation. Nature 2013; 494:238-42. [PMID: 23354054 PMCID: PMC4039389 DOI: 10.1038/nature11846] [Citation(s) in RCA: 807] [Impact Index Per Article: 73.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 12/18/2012] [Indexed: 12/11/2022]
Abstract
The basal ganglia are subcortical nuclei that control voluntary actions, and they are affected by a number of debilitating neurological disorders. The prevailing model of basal ganglia function proposes that two orthogonal projection circuits originating from distinct populations of spiny projection neurons (SPNs) in the striatum--the so-called direct and indirect pathways--have opposing effects on movement: activity of direct-pathway SPNs is thought to facilitate movement, whereas activity of indirect-pathway SPNs is presumed to inhibit movement. This model has been difficult to test owing to the lack of methods to selectively measure the activity of direct- and indirect-pathway SPNs in freely moving animals. Here we develop a novel in vivo method to specifically measure direct- and indirect-pathway SPN activity, using Cre-dependent viral expression of the genetically encoded calcium indicator (GECI) GCaMP3 in the dorsal striatum of D1-Cre (direct-pathway-specific) and A2A-Cre (indirect-pathway-specific) mice. Using fibre optics and time-correlated single-photon counting (TCSPC) in mice performing an operant task, we observed transient increases in neural activity in both direct- and indirect-pathway SPNs when animals initiated actions, but not when they were inactive. Concurrent activation of SPNs from both pathways in one hemisphere preceded the initiation of contraversive movements and predicted the occurrence of specific movements within 500 ms. These observations challenge the classical view of basal ganglia function and may have implications for understanding the origin of motor symptoms in basal ganglia disorders.
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16
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Sun XR, Chen L, Chen WF, Yung WH. Electrophysiological and behavioral effects of group I metabotropic glutamate receptors on pallidal neurons in rats. Brain Res 2012; 1477:1-9. [DOI: 10.1016/j.brainres.2012.08.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 07/20/2012] [Accepted: 08/15/2012] [Indexed: 11/17/2022]
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17
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Osorio-Espinoza A, Alatorre A, Ramos-Jiménez J, Garduño-Torres B, García-Ramírez M, Querejeta E, Arias-Montaño JA. Pre-synaptic histamine H₃ receptors modulate glutamatergic transmission in rat globus pallidus. Neuroscience 2010; 176:20-31. [PMID: 21195747 DOI: 10.1016/j.neuroscience.2010.12.051] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 12/22/2010] [Accepted: 12/24/2010] [Indexed: 02/04/2023]
Abstract
The globus pallidus, a neuronal nucleus involved in the control of motor behavior, expresses high levels of histamine H(3) receptors (H(3)Rs) most likely located on the synaptic afferents to the nucleus. In this work we studied the effect of the activation of rat pallidal H(3)Rs on depolarization-evoked neurotransmitter release from slices, neuronal firing rate in vivo and turning behavior. Perfusion of globus pallidus slices with the selective H(3)R agonist immepip had no effect on the release of [(3)H]-GABA ([(3)H]-γ-aminobutyric acid) or [(3)H]-dopamine evoked by depolarization with high (20 mM) K(+), but significantly reduced [(3)H]-d-aspartate release (-44.8 ± 2.6% and -63.7 ± 6.2% at 30 and 100 nM, respectively). The effect of 30 nM immepip was blocked by 10 μM of the selective H(3)R antagonist A-331440 (4'-[3-[(3(R)-dimethylamino-1-pyrrolidinyl]propoxy]-[1,1-biphenyl]-4'-carbonitrile). Intra-pallidal injection of immepip (0.1 μl, 100 μM) decreased spontaneous neuronal firing rate in anaesthetized rats (peak inhibition 68.8±10.3%), and this effect was reversed in a partial and transitory manner by A-331440 (0.1 μl, 1 mM). In free-moving rats the infusion of immepip (0.5 μl; 10, 50 and 100 μM) into the globus pallidus induced dose-related ipsilateral turning following systemic apomorphine (0.5 mg/kg, s.c.). Turning behavior induced by immepip (0.5 μl, 50 μM) and apomorphine was partially prevented by the local injection of A-331440 (0.5 μl, 1 mM) and was not additive to the turning evoked by the intra-pallidal injection of antagonists at ionotropic glutamate receptors (0.5 μl, 1 mM each of AP-5, dl-2-amino-5-phosphonovaleric acid, and CNQX, 6-nitro-7-sulphamoylbenzo[f]quinoxaline-2,3-dione). These results indicate that pre-synaptic H(3)Rs modulate glutamatergic transmission in rat globus pallidus and thus participate in the control of movement by basal ganglia.
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Affiliation(s)
- A Osorio-Espinoza
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional 2508, Zacatenco, 07360 México, D.F., México
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18
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Latash ML, Mikaelian IL. How long does it take to describe what one sees? The first step using picture description tasks. Hum Mov Sci 2010; 29:369-85. [PMID: 20403643 DOI: 10.1016/j.humov.2009.11.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 07/06/2009] [Accepted: 11/15/2009] [Indexed: 10/19/2022]
Abstract
The study explored the dependences between quantifiable features of a picture and the time it takes to describe it. Six native English speakers and six bilinguals watched pictures presented on the monitor and described them "as quickly and accurately as possible". The bilingual participants performed the test twice, in English and in their native language. The pictures could contain one to six objects. There were four series of trials that differed in the number of characteristics of the objects the participants were instructed to describe. Reaction time showed a modest, close to linear scaling with the number of objects. Both reaction time and speech time were significantly longer for the bilingual participants performing in English as compared to their performance in the native language and to the English speaking participants. The difference in reaction time did not depend on the number of objects. Speech time showed a close to linear scaling with the number of objects within each of the four series. The linear regression coefficient in this relationship increased linearly with the number of characteristics of the objects across all series. The results are discussed in relation to speed-accuracy trade-off and different strategies of picture description.
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Affiliation(s)
- Mark L Latash
- Department of Kinesiology, Rec. Hall-268, Pennsylvania State University, University Park, PA 16802, USA.
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19
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Xue Y, Han XH, Chen L. Effects of Pharmacological Block of GABA(A) Receptors on Pallidal Neurons in Normal and Parkinsonian State. Front Cell Neurosci 2010; 4:2. [PMID: 20204138 PMCID: PMC2831626 DOI: 10.3389/neuro.03.002.2010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Accepted: 01/26/2010] [Indexed: 11/19/2022] Open
Abstract
The globus pallidus plays a central integrative role in the basal ganglia circuitry. Morphological studies have revealed a high level of GABA and GABAA receptors in the globus pallidus. To further investigate the effects of endogenous GABAA neurotransmission in the globus pallidus of normal and parkinsonian rats, in vivo extracellular recording and behavioral tests were performed in the present studies. In normal rats, micro-pressure ejection of GABAA receptor antagonist gabazine (0.1 mM) increased the spontaneous firing rate of pallidal neurons by 28.3%. Furthermore, in 6-hydroxydopamine parkinsonian rats, gabazine increased the firing rate by 46.0% on the lesioned side, which was significantly greater than that on the unlesioned side (21.5%, P < 0.05), as well as that in normal rats (P < 0.05). In the behaving rats, unilateral microinjection of gabazine (0.1 mM) evoked consistent contralateral rotation in normal rats, and significantly potentiated the number of apomorphine-induced contralateral rotations in parkinsonian rats. The present electrophysiological and behavioral findings may provide a rational for further investigations into the potential of pallidal endogenous GABAA neurotransmission in the treatment of Parkinson's disease.
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Affiliation(s)
- Yan Xue
- Department of Physiology, Qingdao University Qingdao, China
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20
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Effects of cobalt and bicuculline on focal microstimulation of rat pallidal neurons in vivo. Brain Stimul 2008; 1:134-50. [DOI: 10.1016/j.brs.2008.05.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2008] [Revised: 05/15/2008] [Accepted: 05/19/2008] [Indexed: 01/11/2023] Open
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21
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Yoshida A, Tanaka M. Enhanced Modulation of Neuronal Activity during Antisaccades in the Primate Globus Pallidus. Cereb Cortex 2008; 19:206-17. [DOI: 10.1093/cercor/bhn069] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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22
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Boyes J, Bolam JP, Shigemoto R, Stanford IM. Functional presynaptic HCN channels in the rat globus pallidus. Eur J Neurosci 2007; 25:2081-92. [PMID: 17439493 DOI: 10.1111/j.1460-9568.2007.05463.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated cation (HCN) channels are expressed postsynaptically in the rodent globus pallidus (GP), where they play several important roles in controlling GP neuronal activity. To further elucidate the role of HCN channels in the GP, immunocytochemical and electrophysiological approaches were used to test the hypothesis that HCN channels are also expressed presynaptically on the local axon collaterals of GP neurons. At the electron microscopic level, immunoperoxidase labelling for HCN1 and HCN2 was localized in GP somata and dendritic processes, myelinated and unmyelinated axons, and axon terminals. One population of labelled terminals formed symmetric synapses with somata and proximal dendrites and were immunoreactive for parvalbumin, consistent with the axon collaterals of GABAergic GP projection neurons. In addition, labelling for HCN2 and, to a lesser degree, HCN1 was observed in axon terminals that formed asymmetric synapses and were immunoreactive for the vesicular glutamate transporter 2. Immunogold labelling demonstrated that HCN1 and HCN2 were located predominantly at extrasynaptic sites along the plasma membrane of both types of terminal. To determine the function of presynaptic HCN channels in the GP, we performed whole-cell recordings from GP neurons in vitro. Bath application of the HCN channel blocker ZD7288 resulted in an increase in the frequency of mIPSCs but had no effect on their amplitude, implying that HCN channels tonically regulate the release of GABA. Their presence, and predicted role in modulating transmitter release, represents a hitherto unidentified mechanism whereby HCN channels influence the activity of GP neurons.
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Affiliation(s)
- Justin Boyes
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK
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23
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Rosas-Arellano A, Ochoa-de la Paz LD, Miledi R, Martínez-Torres A. Brain distribution and molecular cloning of the bovine GABA rho1 receptor. Neurosci Res 2007; 57:347-53. [PMID: 17188384 DOI: 10.1016/j.neures.2006.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Revised: 10/06/2006] [Accepted: 11/06/2006] [Indexed: 10/23/2022]
Abstract
GABA(C) receptors were originally found in the mammalian retina and recent evidence shows that they are also expressed in several areas of the brain, including caudate nucleus, brain stem, pons and corpus callosum. In this study, plasma membranes from the caudate nucleus were microinjected into X. laevis oocytes. This led the oocyte plasma membrane to incorporate functional bicuculline-resistant, Cl(-) conducting bovine GABA receptors, similar to those of the retina. Immunolocalization of the GABA rho1 subunit revealed its expression in bovine neurons in the head of the caudate as well as in the olive, cuneiform and reticular nuclei of the brain stem. The same antibodies failed to show expression in the callosum and pons, where the GABA rho1 mRNA was previously detected. The cloned GABA rho1 sequence predicts a protein with 473 amino acids and 74-93% similarity to other GABA rho1 subunits. Oocytes injected with the cDNA express a non-desensitizing, homomeric receptor with a GABA EC(50)=6.0 microM and a Hill coefficient of 1.8. The results confirm the presence of GABA(C) receptor mRNAs in several areas of the mammalian brain and show that some of these areas express functional GABA rho1 receptors that have the classic GABA(C) receptor characteristics.
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Affiliation(s)
- Abraham Rosas-Arellano
- Instituto de Neurobiología, Laboratorio de Neurobiología Molecular y Celular II, Universidad Nacional Autónoma de México, Km 15.5 Carretera a San Luis Potosí 76001 Juriquilla, Querétaro, México
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