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Vegas-Suárez S, Morera-Herreras T, Requejo C, Lafuente JV, Moratalla R, Miguélez C, Ugedo L. Motor cortico-nigral and cortico-entopeduncular information transmission and its modulation by buspirone in control and after dopaminergic denervation. Front Pharmacol 2022; 13:953652. [PMID: 36133803 PMCID: PMC9483552 DOI: 10.3389/fphar.2022.953652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Cortical information is transferred to the substantia nigra pars reticulata (SNr) and the entopeduncular nucleus (EP), the output structures of the basal ganglia (BG), through three different pathways: the hyperdirect trans-subthalamic and the direct and indirect trans-striatal pathways. The nigrostriatal dopamine (DA) and the activation of 5-HT1A receptors, distributed all along the BG, may modulate cortical information transmission. We aimed to investigate the effect of buspirone (5-HT1A receptor partial agonist) and WAY-100635 (5-HT1A receptor antagonist) on cortico-nigral and cortico-entopeduncular transmission in normal and DA loss conditions. Herein, simultaneous electrical stimulation of the motor cortex and single-unit extracellular recordings of SNr or EP neurons were conducted in urethane-anesthetized sham and 6-hydroxydopamine (6-OHDA)-lesioned rats before and after drug administrations. Motor cortex stimulation evoked monophasic, biphasic, or triphasic responses, combination of an early excitation, an inhibition, and a late excitation in both the SNr and EP, while an altered pattern of evoked response was observed in the SNr after 6-OHDA lesion. Systemic buspirone potentiated the direct cortico-SNr and cortico-EP transmission in sham animals since increased duration of the inhibitory response was observed. In DA denervated animals, buspirone administration enhanced early excitation amplitude in the cortico-SNr transmission. In both cases, the observed effects were mediated via a 5-HT1A-dependent mechanism as WAY-100635 administration blocked buspirone’s effect. These findings suggest that in control condition, buspirone potentiates direct pathway transmission and DA loss modulates responses related to the hyperdirect pathway. Overall, the results may contribute to understanding the role of 5-HT1A receptors and DA in motor cortico-BG circuitry functionality.
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Affiliation(s)
- Sergio Vegas-Suárez
- Department of Pharmacology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Leioa, Spain.,Autonomic and Movement Disorders Unit, Neurodegenerative Diseases, Biocruces Health Research Institute, Barakaldo, Spain.,Cajal Institute, Spanish National Research Council (CSIC), Madrid, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Carlos III Institute of Health (ISCIII), Madrid, Spain
| | - Teresa Morera-Herreras
- Department of Pharmacology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Leioa, Spain.,Autonomic and Movement Disorders Unit, Neurodegenerative Diseases, Biocruces Health Research Institute, Barakaldo, Spain
| | - Catalina Requejo
- Cajal Institute, Spanish National Research Council (CSIC), Madrid, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Carlos III Institute of Health (ISCIII), Madrid, Spain
| | - José Vicente Lafuente
- LaNCE, Department of Neuroscience, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Rosario Moratalla
- Cajal Institute, Spanish National Research Council (CSIC), Madrid, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Carlos III Institute of Health (ISCIII), Madrid, Spain
| | - Cristina Miguélez
- Department of Pharmacology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Leioa, Spain.,Autonomic and Movement Disorders Unit, Neurodegenerative Diseases, Biocruces Health Research Institute, Barakaldo, Spain
| | - Luisa Ugedo
- Department of Pharmacology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Leioa, Spain.,Autonomic and Movement Disorders Unit, Neurodegenerative Diseases, Biocruces Health Research Institute, Barakaldo, Spain
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Oscillatory waveform sharpness asymmetry changes in motor thalamus and motor cortex in a rat model of Parkinson's disease. Exp Neurol 2022; 354:114089. [DOI: 10.1016/j.expneurol.2022.114089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/01/2022] [Accepted: 04/17/2022] [Indexed: 11/23/2022]
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3
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Stefani A, Cerroni R, Pierantozzi M, D’Angelo V, Grandi L, Spanetta M, Galati S. Deep brain stimulation in Parkinson’s disease patients and routine 6‐OHDA rodent models: Synergies and pitfalls. Eur J Neurosci 2020; 53:2322-2343. [DOI: 10.1111/ejn.14950] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 08/09/2020] [Accepted: 08/12/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Alessandro Stefani
- Department of System Medicine Faculty of Medicine and Surgery University of Rome “Tor Vergata” Rome Italy
| | - Rocco Cerroni
- Department of System Medicine Faculty of Medicine and Surgery University of Rome “Tor Vergata” Rome Italy
| | - Mariangela Pierantozzi
- Department of System Medicine Faculty of Medicine and Surgery University of Rome “Tor Vergata” Rome Italy
| | - Vincenza D’Angelo
- Department of System Medicine Faculty of Medicine and Surgery University of Rome “Tor Vergata” Rome Italy
| | - Laura Grandi
- Center for Movement Disorders Neurocenter of Southern Switzerland Lugano Switzerland
| | - Matteo Spanetta
- Department of System Medicine Faculty of Medicine and Surgery University of Rome “Tor Vergata” Rome Italy
| | - Salvatore Galati
- Center for Movement Disorders Neurocenter of Southern Switzerland Lugano Switzerland
- Faculty of Biomedical Sciences Università della Svizzera Italiana Lugano Switzerland
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Stefani A, Cerroni R, Mazzone P, Liguori C, Di Giovanni G, Pierantozzi M, Galati S. Mechanisms of action underlying the efficacy of deep brain stimulation of the subthalamic nucleus in Parkinson's disease: central role of disease severity. Eur J Neurosci 2018; 49:805-816. [DOI: 10.1111/ejn.14088] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 06/19/2018] [Accepted: 07/17/2018] [Indexed: 12/11/2022]
Affiliation(s)
- Alessandro Stefani
- Department of System Medicine UOSD Parkinson Center University of Rome “Tor Vergata” Fondazione Policlinico Tor Vergata viale Oxford 81 Rome 00133 Italy
| | - Rocco Cerroni
- Department of System Medicine UOSD Parkinson Center University of Rome “Tor Vergata” Fondazione Policlinico Tor Vergata viale Oxford 81 Rome 00133 Italy
| | | | - Claudio Liguori
- Department of System Medicine UOSD Parkinson Center University of Rome “Tor Vergata” Fondazione Policlinico Tor Vergata viale Oxford 81 Rome 00133 Italy
| | - Giuseppe Di Giovanni
- Department of Physiology and Biochemistry Faculty of Medicine and Surgery University of Malta La Valletta Malta
| | - Mariangela Pierantozzi
- Department of System Medicine UOSD Parkinson Center University of Rome “Tor Vergata” Fondazione Policlinico Tor Vergata viale Oxford 81 Rome 00133 Italy
| | - Salvatore Galati
- Movement disorders service Neurocenter of Southern Switzerland Lugano Switzerland
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Hirschmann J, Özkurt TE, Butz M, Homburger M, Elben S, Hartmann CJ, Vesper J, Wojtecki L, Schnitzler A. Differential modulation of STN-cortical and cortico-muscular coherence by movement and levodopa in Parkinson's disease. Neuroimage 2012; 68:203-13. [PMID: 23247184 DOI: 10.1016/j.neuroimage.2012.11.036] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/29/2012] [Accepted: 11/15/2012] [Indexed: 11/16/2022] Open
Abstract
Previous research suggests that oscillatory coupling between cortex, basal ganglia and muscles plays an important role in motor behavior. Furthermore, there is evidence that oscillatory coupling is altered in patients with movement disorders such as Parkinson's disease (PD). In this study, we performed simultaneous magnetoencephalography (MEG), local field potential (LFP) and electromyogram (EMG) recordings in PD patients selected for therapeutic subthalamic nucleus (STN) stimulation. Patients were recorded (i) after withdrawal of anti-parkinsonian medication (OFF) and (ii) after levodopa administration (ON). We analyzed STN-cortical and cortico-muscular coherence during static forearm contraction and repetitive hand movement in order to evaluate modulations of coherence by movement and medication. Based on previous results from studies investigating resting state coherence in PD patients, we selected primary motor cortex (M1) and superior temporal gyrus (STG) as regions of interest. We found beta coherence between M1 and STN to be suppressed by administration of levodopa. M1-muscular coherence was strongly reduced in the alpha and beta band during repetitive movement compared to static contraction, but was unaffected by administration of levodopa. Strong STG-STN but not STG-muscular coherence could be observed in the alpha band. Coherence with STG was modulated neither by movement nor by medication. Finally, we found both M1-STN and M1-muscular beta coherence to be negatively correlated with UPDRS akinesia and rigidity sub-scores in the OFF state. The present study provides new insights into the functional roles of STN-cortical and cortico-muscular coherence and their relationship to PD symptoms. The results indicate that STN-cortical and cortico-muscular coupling are correlated, but can be modulated independently. Moreover, they show differences in their frequency-specific topography. We conclude that they represent partly independent sub-loops within the motor system. Given their negative correlation with akinesia, neither can be considered "antikinetic".
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Affiliation(s)
- J Hirschmann
- Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
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6
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Quantitative video-based gait pattern analysis for hemiparkinsonian rats. Med Biol Eng Comput 2012; 50:937-46. [DOI: 10.1007/s11517-012-0933-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 06/05/2012] [Indexed: 10/28/2022]
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Evolution of the dynamic properties of the cortex-basal ganglia network after dopaminergic depletion in rats. Neurobiol Dis 2012; 46:402-13. [PMID: 22353564 DOI: 10.1016/j.nbd.2012.02.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 01/18/2012] [Accepted: 02/04/2012] [Indexed: 11/20/2022] Open
Abstract
It is well established that parkinsonian syndrome is associated with alterations of neuronal activity temporal pattern basal ganglia (BG). An increase in synchronized oscillations has been observed in different BG nuclei in Parkinson's disease patients as well as animal models such as 6-hydroxydopamine treated rats. We recently demonstrated that this increase in oscillatory synchronization is present during high-voltage spindles (HVS) probably underpinned by the disorganization of cortex-BG interactions. Here we investigated the time course of both oscillatory and motor alterations. For that purpose we performed daily simultaneous recordings of neuronal activity in motor cortex, striatum and substantia nigra pars reticulata (SNr), before and after 6-hydroxydopamine lesion in awake rats. After a brief non-dopamine-specific desynchronization, oscillatory activity first increased during HVS followed by progressive motor impairment and the shortening of SNr activation delay. While the oscillatory firing increase reflects dopaminergic depletion, response alteration in SNr neurons is closely related to motor symptom.
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Mathai A, Smith Y. The corticostriatal and corticosubthalamic pathways: two entries, one target. So what? Front Syst Neurosci 2011; 5:64. [PMID: 21866224 PMCID: PMC3149683 DOI: 10.3389/fnsys.2011.00064] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 07/21/2011] [Indexed: 11/13/2022] Open
Abstract
The basal ganglia receive cortical inputs through two main stations - the striatum and the subthalamic nucleus (STN). The information flowing along the corticostriatal system is transmitted to the basal ganglia circuitry via the "direct and indirect" striatofugal pathways, while information that flows through the STN is transmitted along the so-called "hyperdirect" pathway. The functional significance of this dual entry system is not clear. Although the corticostriatal system has been thoroughly characterized anatomically and electrophysiologically, such is not the case for the corticosubthalamic system. In order to provide further insights into the intricacy of this complex anatomical organization, this review examines and compares the anatomical and functional organization of the corticostriatal and corticosubthalamic systems, and highlights some key issues that must be addressed to better understand the mechanisms by which these two neural systems may interact to regulate basal ganglia functions and dysfunctions.
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Affiliation(s)
- Abraham Mathai
- Yerkes National Primate Research Center, Emory University Atlanta, GA, USA
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Zold CL, Kasanetz F, Pomata PE, Belluscio MA, Escande MV, Galinanes GL, Riquelme LA, Murer MG. Striatal gating through up states and oscillations in the basal ganglia: Implications for Parkinson's disease. ACTA ACUST UNITED AC 2011; 106:40-6. [PMID: 21767642 DOI: 10.1016/j.jphysparis.2011.06.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Accepted: 06/24/2011] [Indexed: 11/25/2022]
Abstract
Up states are a hallmark of striatal physiology. Spontaneous activity in the thalamo-cortical network drives robust plateau depolarizations in the medium spiny projection neurons of the striatum. Medium spiny neuron firing is only possible during up states and is very tightly regulated by dopamine and NMDA receptors. In a rat model of Parkinson's disease the medium spiny neurons projecting to the globus pallidus (indirect pathway) show more depolarized up states and increased firing. This is translated into abnormal patterns of synchronization between the globus pallidus and frontal cortex, which are believed to underlie the symptoms of Parkinson's disease. Here we review our work in the field and propose a mechanism through which the lack of D2 receptor stimulation in the striatum allows the establishment of fixed routes of information flow in the cortico-striato-pallidal network.
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Affiliation(s)
- Camila L Zold
- Neural Circuit Physiology Lab., Systems Neuroscience Group, Department of Physiology and Biophysics, University of Buenos Aires School of Medicine, 2155 Paraguay St., Buenos Aires 1121, Argentina.
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10
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Walters JR, Bergstrom DA. Synchronous Activity in Basal Ganglia Circuits. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2010. [DOI: 10.1016/b978-0-12-374767-9.00025-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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11
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Parr-Brownlie LC, Poloskey SL, Bergstrom DA, Walters JR. Parafascicular thalamic nucleus activity in a rat model of Parkinson's disease. Exp Neurol 2009; 217:269-81. [PMID: 19268664 DOI: 10.1016/j.expneurol.2009.02.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Revised: 01/26/2009] [Accepted: 02/24/2009] [Indexed: 10/21/2022]
Abstract
Parkinson's disease is associated with increased oscillatory firing patterns in basal ganglia output, which are thought to disrupt thalamocortical activity. However, it is unclear how specific thalamic nuclei are affected by these changes in basal ganglia activity. The thalamic parafascicular nucleus (PFN) receives input from basal ganglia output nuclei and directly projects to the subthalamic nucleus (STN), striatum and cortex; thus basal ganglia-mediated changes on PFN activity may further impact basal ganglia and cortical functions. To investigate the impact of increased oscillatory activity in basal ganglia output on PFN activity after dopamine cell lesion, PFN single-unit and local field potential activities were recorded in neurologically intact (control) rats and in both non-lesioned and dopamine lesioned hemispheres of unilateral 6-hydroxydopamine lesioned rats anesthetized with urethane. Firing rates were unchanged 1-2 weeks after lesion; however, significantly fewer spontaneously active PFN neurons were evident. Firing pattern assessments after lesion showed that a larger proportion of PFN spike trains had 0.3-2.5 Hz oscillatory activity and significantly fewer spike trains exhibited low threshold calcium spike (LTS) bursts. In paired recordings, more PFN-STN spike oscillations were significantly correlated, but as these oscillations were in-phase, results are inconsistent with feedforward control of PFN activity by inhibitory oscillatory basal ganglia output. Furthermore, the decreased incidence of LTS bursts is incompatible with inhibitory basal ganglia output inducing rebound bursting in PFN after dopamine lesion. Together, results show that robust oscillatory activity observed in basal ganglia output nuclei after dopamine cell lesion does not directly drive changes in PFN oscillatory activity.
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Affiliation(s)
- Louise C Parr-Brownlie
- Neurophysiological Pharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Building 35 Room 1C 905, Bethesda, MD 20892-3702 USA.
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12
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Pomata PE, Belluscio MA, Riquelme LA, Murer MG. NMDA receptor gating of information flow through the striatum in vivo. J Neurosci 2008; 28:13384-9. [PMID: 19074011 PMCID: PMC6671737 DOI: 10.1523/jneurosci.4343-08.2008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 10/07/2008] [Indexed: 11/21/2022] Open
Abstract
A role of NMDA receptors in corticostriatal synaptic plasticity is widely acknowledged. However, the conditions that allow NMDA receptor activation in the striatum in vivo remain obscure. Here we show that NMDA receptors contribute to sustain the membrane potential of striatal medium spiny projection neurons close to threshold during spontaneous UP states in vivo. Moreover, we found that the blockade of striatal NMDA receptors reduces markedly the spontaneous firing of ensembles of medium spiny neurons during slow waves in urethane-anesthetized rats. We speculate that recurrent activation of NMDA receptors during UP states allows off-line information flow through the striatum and system level consolidation during habit formation.
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Affiliation(s)
- Pablo E Pomata
- Laboratorio de Fisiología de Circuitos Neuronales, Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina.
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Ballion B, Mallet N, Bézard E, Lanciego JL, Gonon F. Intratelencephalic corticostriatal neurons equally excite striatonigral and striatopallidal neurons and their discharge activity is selectively reduced in experimental parkinsonism. Eur J Neurosci 2008; 27:2313-21. [PMID: 18445222 DOI: 10.1111/j.1460-9568.2008.06192.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Striatonigral and striatopallidal neurons form distinct populations of striatal projection neurons. Their discharge activity is imbalanced after dopaminergic degeneration in Parkinson's disease. Striatal projection neurons receive massive cortical excitatory inputs from bilateral intratelencephalic (IT) neurons projecting to both the ipsilateral and contralateral striatum and from collateral axons of ipsilateral neurons that send their main axon through the pyramidal tract (PT). Previous anatomical studies in rats suggested that IT and PT inputs preferentially excite striatonigral and striatopallidal neurons, respectively. Here we used electrophysiological criteria to identify them with antidromic stimulations. We show that the spontaneous discharge activity of IT neurons is depressed, whereas that of PT neurons is not affected in the rat cortex ipsilateral to 6-hydroxydopamine injection. However, our functional experiments do not support the hypothesis of a differential cortical input to striatal pathways. Firstly, although the conduction velocity of PT neurons is 4.6 times faster than that of IT neurons, identified striatopallidal and striatonigral neurons exhibit identical latencies of their spike responses to electrical stimulation of the ipsilateral cortex. Secondly, although PT neurons are ipsilateral, both striatal populations exhibit similar sensitivity to the stimulation of the ipsilateral and contralateral cortex. We suggest that IT neurons provide the main excitatory input to both striatal populations and that the corticostriatal PT input is weaker. Therefore, our functional data do not support our previous hypothesis that the deficit of IT neurons associated with the dopaminergic depletion might contribute to the striatal imbalance. This imbalance might rather result from intrinsic striatal mechanisms.
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Affiliation(s)
- Bérangère Ballion
- Centre National de la Recherche Scientifique UMR 5227, case 63, Université Victor Segalen Bordeaux 2, 33076 Bordeaux, France
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Dejean C, Gross CE, Bioulac B, Boraud T. Dynamic Changes in the Cortex-Basal Ganglia Network After Dopamine Depletion in the Rat. J Neurophysiol 2008; 100:385-96. [DOI: 10.1152/jn.90466.2008] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is well established that parkinsonian syndrome is associated with alterations in the temporal pattern of neuronal activity and local field potentials in the basal ganglia (BG). An increase in synchronized oscillations has been observed in different BG nuclei in parkinsonian patients and animal models of this disease. However, the mechanisms underlying this phenomenon remain unclear. This study investigates the functional connectivity in the cortex-BG network of a rodent model of Parkinson's disease. Single neurons and local field potentials were simultaneously recorded in the motor cortex, the striatum, and the substantia nigra pars reticulata (SNr) of freely moving rats, and high-voltage spindles (HVSs) were used to compare signal transmission before and after dopaminergic depletion. It is shown that dopaminergic lesion results in a significant enhancement of oscillatory synchronization in the BG: the coherence between pairs of structures increased significantly and the percentage of oscillatory auto- and cross-correlograms. HVS episodes were also more numerous and longer. These changes were associated with a shortening of the latency of SNr response to cortical activation, from 40.5 ± 4.8 to 10.2 ± 1.07 ms. This result suggests that, in normal conditions, SNr neurons are likely to be driven by late inputs from the indirect pathway; however, after the lesion, their shorter latency also indicates an overactivation of the hyperdirect pathway. This study confirms that neuronal signal transmission is altered in the BG after dopamine depletion but also provides qualitative evidence for these changes at the cellular level.
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Zold CL, Larramendy C, Riquelme LA, Murer MG. Distinct changes in evoked and resting globus pallidus activity in early and late Parkinson's disease experimental models. Eur J Neurosci 2007; 26:1267-79. [PMID: 17767504 DOI: 10.1111/j.1460-9568.2007.05754.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The main clinical manifestations of Parkinson's disease are caused by alterations of basal ganglia activity that are tied in with the progressive loss of mesencephalic dopaminergic neurons. Recent theoretical and modeling studies have suggested that changes in resting neuronal activity occurred later in the course of the disease than those evoked by phasic cortical input. However, there is no empirical support for this proposal. Here we report a marked increase in the responsiveness of globus pallidus neurons to electrical motor cortex stimulation, in the absence of noticeable changes in resting activity, in anesthetized rats that had consistently shown a deficit in forelimb use during behavioral testing before the experiments, and had approximately 45% dopamine neurons spared in the substantia nigra. Pallidal neurons were also over-responsive to motor cortex stimulation and lost spatial selectivity for cortical inputs in rats with extensive nigrostriatal damage. After partial lesions, over-responsiveness was mainly due to an increased proportion of neurons showing excitatory responses, while extensive lesions led to an increased likelihood of inhibitory responding neurons. Changes in resting neuronal activity, comprising pauses disrupting tonic discharge, occurred across different global brain states, including an activated condition which shares similarities with natural patterns of cortical activity seen in awake states and rapid eye-movement sleep, but only after massive nigrostriatal degeneration. These results suggest that a loss of functional segregation and an abnormal temporal encoding of phasic cortical inputs by globus pallidus neurons may contribute to inducing early motor impairment in Parkinson's disease.
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Affiliation(s)
- Camila L Zold
- Laboratorio de Fisiología de Circuitos Neuronales, Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Ciudad de Buenos Aires (CP1121), Argentina.
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