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MacIver CL, Bailey G, Laguna PL, Wadon ME, Schalkamp AK, Sandor C, Jones DK, Tax CMW, Peall KJ. Macro- and micro-structural insights into primary dystonia: a UK Biobank study. J Neurol 2024; 271:1416-1427. [PMID: 37995010 PMCID: PMC10896800 DOI: 10.1007/s00415-023-12086-2] [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: 09/05/2023] [Revised: 10/25/2023] [Accepted: 10/27/2023] [Indexed: 11/24/2023]
Abstract
BACKGROUND Dystonia is a hyperkinetic movement disorder with key motor network dysfunction implicated in pathophysiology. The UK Biobank encompasses > 500,000 participants, of whom 42,565 underwent brain MRI scanning. This study applied an optimized pre-processing pipeline, aimed at better accounting for artifact and improving data reliability, to assess for grey and white matter structural MRI changes between individuals diagnosed with primary dystonia and an unaffected control cohort. METHODS Individuals with dystonia (n = 76) were identified from the UK Biobank using published algorithms, alongside an age- and sex-matched unaffected control cohort (n = 311). Grey matter morphometric and diffusion measures were assessed, together with white matter diffusion tensor and diffusion kurtosis metrics using tractography and tractometry. Post-hoc Neurite Orientation and Density Distribution Imaging (NODDI) was also undertaken for tracts in which significant differences were observed. RESULTS Grey matter tremor-specific striatal differences were observed, with higher radial kurtosis. Tractography identified no white matter differences, however segmental tractometry identified localised differences, particularly in the superior cerebellar peduncles and anterior thalamic radiations, including higher fractional anisotropy and lower orientation distribution index in dystonia, compared to controls. Additional tremor-specific changes included lower neurite density index in the anterior thalamic radiations. CONCLUSIONS Analysis of imaging data from one of the largest dystonia cohorts to date demonstrates microstructural differences in cerebellar and thalamic white matter connections, with architectural differences such as less orientation dispersion potentially being a component of the morphological structural changes implicated in dystonia. Distinct tremor-related imaging features are also implicated in both grey and white matter.
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Affiliation(s)
- Claire L MacIver
- Division of Psychological Medicine and Clinical Neurosciences, Neuroscience and Mental Health Research Institute, Cardiff University School of Medicine, Cardiff, UK.
- Cardiff University Brain Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK.
| | - Grace Bailey
- Division of Psychological Medicine and Clinical Neurosciences, Neuroscience and Mental Health Research Institute, Cardiff University School of Medicine, Cardiff, UK
| | - Pedro Luque Laguna
- Cardiff University Brain Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK
| | - Megan E Wadon
- Cardiff University Brain Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK
| | - Ann-Kathrin Schalkamp
- Division of Psychological Medicine and Clinical Neurosciences, UK Dementia Research Institute, Cardiff University, Cardiff, UK
| | - Cynthia Sandor
- Division of Psychological Medicine and Clinical Neurosciences, UK Dementia Research Institute, Cardiff University, Cardiff, UK
| | - Derek K Jones
- Cardiff University Brain Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK
| | - Chantal M W Tax
- Cardiff University Brain Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Kathryn J Peall
- Division of Psychological Medicine and Clinical Neurosciences, Neuroscience and Mental Health Research Institute, Cardiff University School of Medicine, Cardiff, UK
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2
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Rey Hipolito AG, van der Heijden ME, Sillitoe RV. Physiology of Dystonia: Animal Studies. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2023; 169:163-215. [PMID: 37482392 DOI: 10.1016/bs.irn.2023.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Dystonia is currently ranked as the third most prevalent motor disorder. It is typically characterized by involuntary muscle over- or co-contractions that can cause painful abnormal postures and jerky movements. Dystonia is a heterogenous disorder-across patients, dystonic symptoms vary in their severity, body distribution, temporal pattern, onset, and progression. There are also a growing number of genes that are associated with hereditary dystonia. In addition, multiple brain regions are associated with dystonic symptoms in both genetic and sporadic forms of the disease. The heterogeneity of dystonia has made it difficult to fully understand its underlying pathophysiology. However, the use of animal models has been used to uncover the complex circuit mechanisms that lead to dystonic behaviors. Here, we summarize findings from animal models harboring mutations in dystonia-associated genes and phenotypic animal models with overt dystonic motor signs resulting from spontaneous mutations, neural circuit perturbations, or pharmacological manipulations. Taken together, an emerging picture depicts dystonia as a result of brain-wide network dysfunction driven by basal ganglia and cerebellar dysfunction. In the basal ganglia, changes in dopaminergic, serotonergic, noradrenergic, and cholinergic signaling are found across different animal models. In the cerebellum, abnormal burst firing activity is observed in multiple dystonia models. We are now beginning to unveil the extent to which these structures mechanistically interact with each other. Such mechanisms inspire the use of pre-clinical animal models that will be used to design new therapies including drug treatments and brain stimulation.
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Affiliation(s)
- Alejandro G Rey Hipolito
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, United States
| | - Meike E van der Heijden
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, United States; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, United States
| | - Roy V Sillitoe
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States; Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, United States; Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States; Development, Disease Models & Therapeutics Graduate Program, Baylor College of Medicine, Houston, TX, United States; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, United States.
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3
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Burbaud P, Courtin E, Ribot B, Guehl D. Basal ganglia: From the bench to the bed. Eur J Paediatr Neurol 2022; 36:99-106. [PMID: 34953339 DOI: 10.1016/j.ejpn.2021.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 12/01/2021] [Indexed: 11/24/2022]
Abstract
The basal ganglia (BG) encompass a set of archaic structures of the vertebrate brain that have evolved relatively little during the phylogenetic process. From an anatomic point of view, they are widely distributed throughout brain from the telencephalon to the mesencephalon. The fact that they have been preserved through evolution suggests that they may play a critical role in behavioral monitoring. Indeed, a line of evidence suggests that they are involved in the building of behavioral routines and habits that drive most of our activities in everyday life. In this article, we first examine the organization and physiology of the basal ganglia to explain their function in the control of behavior. Then, we show how disruption of the putamen, and to a lesser extent of the cerebellum, might lead to various dystonic syndromes that frequently arise during childhood.
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Affiliation(s)
- P Burbaud
- Centre Hospitalier Universitaire de Bordeaux, Institut des Maladies Neurodégénératives, CNRS, University of Bordeaux, France.
| | - E Courtin
- Centre Hospitalier Universitaire de Bordeaux, Institut des Maladies Neurodégénératives, CNRS, University of Bordeaux, France
| | - B Ribot
- Centre Hospitalier Universitaire de Bordeaux, Institut des Maladies Neurodégénératives, CNRS, University of Bordeaux, France
| | - D Guehl
- Centre Hospitalier Universitaire de Bordeaux, Institut des Maladies Neurodégénératives, CNRS, University of Bordeaux, France
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4
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Ghit A, Assal D, Al-Shami AS, Hussein DEE. GABA A receptors: structure, function, pharmacology, and related disorders. J Genet Eng Biotechnol 2021; 19:123. [PMID: 34417930 PMCID: PMC8380214 DOI: 10.1186/s43141-021-00224-0] [Citation(s) in RCA: 109] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 08/08/2021] [Indexed: 02/03/2023]
Abstract
Background γ-Aminobutyric acid sub-type A receptors (GABAARs) are the most prominent inhibitory neurotransmitter receptors in the CNS. They are a family of ligand-gated ion channel with significant physiological and therapeutic implications. Main body GABAARs are heteropentamers formed from a selection of 19 subunits: six α (alpha1-6), three β (beta1-3), three γ (gamma1-3), three ρ (rho1-3), and one each of the δ (delta), ε (epsilon), π (pi), and θ (theta) which result in the production of a considerable number of receptor isoforms. Each isoform exhibits distinct pharmacological and physiological properties. However, the majority of GABAARs are composed of two α subunits, two β subunits, and one γ subunit arranged as γ2β2α1β2α1 counterclockwise around the center. The mature receptor has a central chloride ion channel gated by GABA neurotransmitter and modulated by a variety of different drugs. Changes in GABA synthesis or release may have a significant effect on normal brain function. Furthermore, The molecular interactions and pharmacological effects caused by drugs are extremely complex. This is due to the structural heterogeneity of the receptors, and the existence of multiple allosteric binding sites as well as a wide range of ligands that can bind to them. Notably, dysfunction of the GABAergic system contributes to the development of several diseases. Therefore, understanding the relationship between GABAA receptor deficits and CNS disorders thus has a significant impact on the discovery of disease pathogenesis and drug development. Conclusion To date, few reviews have discussed GABAA receptors in detail. Accordingly, this review aims to summarize the current understanding of the structural, physiological, and pharmacological properties of GABAARs, as well as shedding light on the most common associated disorders.
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Affiliation(s)
- Amr Ghit
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy. .,Department of Biotechnology, Institute of Graduate Studies and Research (IGSR), Alexandria University, Alexandria, Egypt.
| | - Dina Assal
- Department of Biotechnology, American University in Cairo (AUC), Cairo, Egypt
| | - Ahmed S Al-Shami
- Department of Biotechnology, Institute of Graduate Studies and Research (IGSR), Alexandria University, Alexandria, Egypt.,Department of Zoology, Faculty of Science, Alexandria University, Alexandria, Egypt
| | - Diaa Eldin E Hussein
- Animal Health Research Institute (AHRI), Agricultural Research Center (ARC), Port of Alexandria, Alexandria, Egypt
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5
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Groth CL, Brown M, Honce JM, Shelton E, Sillau SH, Berman BD. Cervical Dystonia Is Associated With Aberrant Inhibitory Signaling Within the Thalamus. Front Neurol 2021; 11:575879. [PMID: 33633655 PMCID: PMC7900407 DOI: 10.3389/fneur.2020.575879] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 09/14/2020] [Indexed: 12/20/2022] Open
Abstract
Objective: The objective of this study is to investigate whether alterations in the neurotransmission of gamma-aminobutyric acid (GABA) in the thalamus are present in patients with cervical dystonia compared to healthy controls. Methods: GABA magnetic resonance spectroscopy was used to investigate concentration levels of GABA in the thalamus of cervical dystonia patients (n = 17) compared to healthy controls (n = 18). Additionally, a focused post hoc analysis of thalamic GABAA receptor availability data in a similar cohort (n = 15 for both groups) using data from a previously collected 11C-flumazenil positron emission tomography study was performed. Group comparisons for all evaluations were performed using two-sided t-tests with adjustments for age and sex, and Bonferroni correction for multiple comparisons was applied. Spearman's coefficient was used to test correlations. Results: We found significantly reduced GABA+/Cre levels in the thalamus of cervical dystonia patients compared to controls, and these levels positively correlated with disease duration. Although mean thalamic GABAA receptor availability did not differ between patients and controls, GABAA availability negatively correlated with both disease duration and dystonia severity. Conclusions: These findings support that aberrant inhibitory signaling within the thalamus contributes to the pathophysiology of cervical dystonia. Additionally, these results suggest that an inadequate ability to compensate for the loss of GABA through upregulation of GABAA receptors may underlie more severe symptoms.
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Affiliation(s)
- Christopher L Groth
- Department of Neurology, University of Iowa Hospitals and Clinics, Iowa City, IA, United States.,Department of Neurology, University of Colorado Anschutz Medical, Aurora, CO, United States
| | - Mark Brown
- Department of Radiology, University of Colorado Anschutz Medical, Aurora, CO, United States
| | - Justin M Honce
- Department of Radiology, University of Colorado Anschutz Medical, Aurora, CO, United States
| | - Erika Shelton
- Department of Neurology, University of Colorado Anschutz Medical, Aurora, CO, United States
| | - Stefan H Sillau
- Department of Neurology, University of Colorado Anschutz Medical, Aurora, CO, United States
| | - Brian D Berman
- Department of Neurology, University of Colorado Anschutz Medical, Aurora, CO, United States.,Department of Radiology, University of Colorado Anschutz Medical, Aurora, CO, United States.,Neurology Section, Denver VA Medical Center, Aurora, CO, United States
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Neuronal Activity of Pallidal Versus Cerebellar Receiving Thalamus in Patients with Cervical Dystonia. THE CEREBELLUM 2020; 20:151-159. [PMID: 33009654 DOI: 10.1007/s12311-020-01194-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/20/2020] [Indexed: 10/23/2022]
Abstract
Cervical dystonia (CD) is a movement disorder characterized by a stereotyped pattern of involuntary turning or tilting of the head, often combined with jerky or tremulous movements. Hypotheses for the origin of CD have traditionally focused on the basal ganglia, but the contemporary discussion has considered the potential role of altered cerebellar function. As basal ganglia and the cerebellum largely project to the different thalamic nuclei, alterations in pallidal versus cerebellar output could be reflected in the activity of these thalamic regions. In this study, we analyzed a unique historic database where the single-unit activity of pallidal and cerebellar receiving thalamic nuclei was measured en route to the mesencephalon. We compared the single-unit activity of pallidal and cerebellar receiving thalamic neurons in three groups of CD patients manifesting as pure dystonia, pure jerky head oscillations, and dystonia plus jerky head oscillations. We found that among different CD manifestations, the characteristics of neuronal firing, such as burst versus a single-spike pattern, vary in cerebellar thalamic receiving nuclei. The cerebellar receiving region in patients with jerky oscillations had single-spikes neurons primarily. Wherein the manifestation of CD did not influence pattern distribution in the pallidal receiving thalamic area. We also found increased neuronal firing rate correlated with strength of theta-band neuronal oscillations during muscle contractions associated with dystonia. These results demonstrate that the manifestations of CD, such as pure dystonia, pure jerky head oscillations, or dystonia and jerky head oscillations, determine the thalamic neuronal properties.
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Ribot B, Aupy J, Vidailhet M, Mazère J, Pisani A, Bezard E, Guehl D, Burbaud P. Dystonia and dopamine: From phenomenology to pathophysiology. Prog Neurobiol 2019; 182:101678. [PMID: 31404592 DOI: 10.1016/j.pneurobio.2019.101678] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/19/2019] [Accepted: 07/31/2019] [Indexed: 11/30/2022]
Abstract
A line of evidence suggests that the pathophysiology of dystonia involves the striatum, whose activity is modulated among other neurotransmitters, by the dopaminergic system. However, the link between dystonia and dopamine appears complex and remains unclear. Here, we propose a physiological approach to investigate the clinical and experimental data supporting a role of the dopaminergic system in the pathophysiology of dystonic syndromes. Because dystonia is a disorder of motor routines, we first focus on the role of dopamine and striatum in procedural learning. Second, we consider the phenomenology of dystonia from every angle in order to search for features giving food for thought regarding the pathophysiology of the disorder. Then, for each dystonic phenotype, we review, when available, the experimental and imaging data supporting a connection with the dopaminergic system. Finally, we propose a putative model in which the different phenotypes could be explained by changes in the balance between the direct and indirect striato-pallidal pathways, a process critically controlled by the level of dopamine within the striatum. Search strategy and selection criteria References for this article were identified through searches in PubMed with the search terms « dystonia », « dopamine", « striatum », « basal ganglia », « imaging data », « animal model », « procedural learning », « pathophysiology », and « plasticity » from 1998 until 2018. Articles were also identified through searches of the authors' own files. Only selected papers published in English were reviewed. The final reference list was generated on the basis of originality and relevance to the broad scope of this review.
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Affiliation(s)
- Bastien Ribot
- Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France
| | - Jérome Aupy
- Service de Neurophysiologie Clinique, Hôpital Pellegrin, place Amélie-Raba-Léon, 33076 Bordeaux, France; Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France
| | - Marie Vidailhet
- AP-HP, Department of Neurology, Groupe Hospitalier Pitié-Salpêtrière, Paris, France; Sorbonne Université, Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière UPMC Univ Paris 6 UMR S 1127, Inserm U 1127, CNRS UMR 7225, Paris, France
| | - Joachim Mazère
- Université de Bordeaux, INCIA, UMR 5287, F-33000 Bordeaux, France; CNRS, INCIA, UMR 5287, F-33000 Bordeaux, France; Service de médecine nucléaire, CHU de Bordeaux, France
| | - Antonio Pisani
- Department of Neuroscience, University "Tor Vergata'', Rome, Italy; Laboratory of Neurophysiology and Plasticity, Fondazione Santa Lucia I.R.C.C.S., Rome, Italy
| | - Erwan Bezard
- Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France
| | - Dominique Guehl
- Service de Neurophysiologie Clinique, Hôpital Pellegrin, place Amélie-Raba-Léon, 33076 Bordeaux, France; Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France
| | - Pierre Burbaud
- Service de Neurophysiologie Clinique, Hôpital Pellegrin, place Amélie-Raba-Léon, 33076 Bordeaux, France; Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France.
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8
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Disinhibition of the Nucleus Accumbens Leads to Macro-Scale Hyperactivity Consisting of Micro-Scale Behavioral Segments Encoded by Striatal Activity. J Neurosci 2019; 39:5897-5909. [PMID: 31126998 DOI: 10.1523/jneurosci.3120-18.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 05/14/2019] [Accepted: 05/16/2019] [Indexed: 12/14/2022] Open
Abstract
The striatum comprises of multiple functional territories involved with multilevel control of behavior. Disinhibition of different functional territories leads to territory-specific hyperkinetic and hyperbehavioral symptoms. The ventromedial striatum, including the nucleus accumbens (NAc) core, is typically associated with limbic input but was historically linked to high-level motor control. In this study, performed in female Long-Evans rats, we show that the NAc core directly controls motor behavior on multiple timescales. On the macro-scale, following NAc disinhibition, the animals manifested prolonged hyperactivity, expressed as excessive normal behavior, whereas on the micro-scale multiple behavior transitions occurred, generating short movement segments. The underlying striatal network displayed population-based local field potential transient deflections (LFP spikes) whose rate determined the magnitude of the hyperactivity and whose timing corresponded to unitary behavioral transition events. Individual striatal neurons preserved normal baseline activity and network interactions following the disinhibition, maintaining the normal encoding of behavioral primitives and forming a sparse link between the LFP spikes and single neuron activity. Disinhibition of this classically limbic territory leads to profound motor changes resembling hyperactivity and attention deficit. These behavioral and neuronal results highlight the direct interplay on multiple timescales between different striatal territories during normal and pathological conditions.SIGNIFICANCE STATEMENT The nucleus accumbens (NAc) is a key part of the striatal limbic territory. In the current study we show that this classically limbic area directly controls motor behavior on multiple timescales. Focal disinhibition of the NAc core in freely behaving rats led to macro-scale hyperactivity and micro-scale behavioral transitions, symptoms typically associated with attention deficit hyperactivity disorder. The behavioral changes were encoded by the striatal LFP signal and single-unit spiking activity in line with the neuronal changes observed during tic expression following disinhibition of the striatal motor territory. These results point to the need to extend the existing parallel functional pathway concept of basal ganglia function to include the study of limbic-motor cross-territory interactions in both health and disease.
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Welter ML, Grabli D, Karachi C, Jodoin N, Fernandez-Vidal S, Brun Y, Navarro S, Rogers A, Cornu P, Pidoux B, Yelnik J, Roze E, Bardinet E, Vidailhet M. Pallidal activity in myoclonus dystonia correlates with motor signs. Mov Disord 2015; 30:992-6. [PMID: 25880339 DOI: 10.1002/mds.26244] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 03/18/2015] [Accepted: 03/21/2015] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Myoclonus-dystonia related to epsilon-sarcoglycan gene mutations is characterized by myoclonic jerks and mild to moderate dystonia. The role of basal ganglia dysfunction in the pathogenesis is unknown. METHODS Pallidal neuronal activity was recorded in six myoclonus-dystonia and six primary generalized dystonia patients operated on for internal globus pallidus deep brain stimulation. RESULTS In myoclonus-dystonia patients compared with primary-dystonia patients, internal pallidum neurons showed higher burst frequency, lower mean burst, and pause durations. External pallidum neurons showed higher mean pause frequency. Oscillatory activity was present in 33% and 35% of internal pallidum neurons in myoclonus-dystonia and primary-dystonia patients, respectively, predominantly in the theta frequency band (3-8 Hz). In myoclonus-dystonia patients with more severe myoclonus, internal pallidum neurons exhibited a higher bursting activity with high intraburst frequency and lower oscillatory activity frequency. CONCLUSIONS Myoclonus-dystonia appears to be related to specific changes in internal pallidum activity, leading to disruption in striato-pallido-thalamo-cortical circuits. © 2015 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Marie-Laure Welter
- Université Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle épiniere (CRICM), UMR-S975, Paris, France.,Inserm, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Centre d'Investigation Clinique Pitié Neurosciences (Inserm CIC-1422), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France.,Département de Neurologie, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - David Grabli
- Université Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle épiniere (CRICM), UMR-S975, Paris, France.,Inserm, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Centre d'Investigation Clinique Pitié Neurosciences (Inserm CIC-1422), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France.,Département de Neurologie, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Carine Karachi
- Université Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle épiniere (CRICM), UMR-S975, Paris, France.,Inserm, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Centre d'Investigation Clinique Pitié Neurosciences (Inserm CIC-1422), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France.,Service de Neurochirurgie, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Nicolas Jodoin
- Centre d'Investigation Clinique Pitié Neurosciences (Inserm CIC-1422), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France.,Service de Neurologie, Centre hospitalier de l'Université de Montréal, Montréal, Québec, Canada
| | - Sara Fernandez-Vidal
- Université Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle épiniere (CRICM), UMR-S975, Paris, France.,Centre de Neuroimagerie de Recherche (CENIR), Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Yohann Brun
- Université Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle épiniere (CRICM), UMR-S975, Paris, France.,Inserm, U1127, Paris, France.,CNRS, UMR 7225, Paris, France
| | - Soledad Navarro
- Service de Neurochirurgie, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Alister Rogers
- Service de Neurochirurgie, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Philippe Cornu
- Service de Neurochirurgie, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Bernard Pidoux
- Service de Neurochirurgie, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Jérôme Yelnik
- Université Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle épiniere (CRICM), UMR-S975, Paris, France.,Inserm, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Centre d'Investigation Clinique Pitié Neurosciences (Inserm CIC-1422), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Emmanuel Roze
- Université Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle épiniere (CRICM), UMR-S975, Paris, France.,Inserm, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Centre d'Investigation Clinique Pitié Neurosciences (Inserm CIC-1422), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France.,Département de Neurologie, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Eric Bardinet
- Université Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle épiniere (CRICM), UMR-S975, Paris, France.,Centre de Neuroimagerie de Recherche (CENIR), Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Marie Vidailhet
- Université Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle épiniere (CRICM), UMR-S975, Paris, France.,Inserm, U1127, Paris, France.,CNRS, UMR 7225, Paris, France.,Centre d'Investigation Clinique Pitié Neurosciences (Inserm CIC-1422), Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France.,Département de Neurologie, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
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Wilson BK, Hess EJ. Animal models for dystonia. Mov Disord 2014; 28:982-9. [PMID: 23893454 DOI: 10.1002/mds.25526] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/19/2013] [Accepted: 04/29/2013] [Indexed: 01/28/2023] Open
Abstract
Symptomatic animal models have clinical features consistent with human disorders and are often used to identify the anatomical and physiological processes involved in the expression of symptoms and to experimentally demonstrate causality where it would be infeasible in the patient population. Rodent and primate models of dystonia have identified basal ganglia abnormalities, including alterations in striatal GABAergic (ie, transmitting or secreting γ-aminobutyric acid) and dopaminergic transmission. Symptomatic animal models have also established the critical role of the cerebellum in dystonia, particularly abnormal glutamate signaling and aberrant Purkinje cell activity. Further, experiments suggest that the basal ganglia and cerebellum are nodes in an integrated network that is dysfunctional in dystonia. The knowledge gained from experiments in symptomatic animal models may serve as the foundation for the development of novel therapeutic interventions to treat dystonia. © 2013 Movement Disorder Society.
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Affiliation(s)
- Bethany K Wilson
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
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11
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Bioulac B, Burbaud P, Cazalets JR, Gross C, Michelet T. Funzioni motorie. Neurologia 2013. [DOI: 10.1016/s1634-7072(13)65020-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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12
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van der Salm SMA, van der Meer JN, Nederveen AJ, Veltman DJ, van Rootselaar AF, Tijssen MAJ. Functional MRI study of response inhibition in myoclonus dystonia. Exp Neurol 2013; 247:623-9. [PMID: 23474191 DOI: 10.1016/j.expneurol.2013.02.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 02/22/2013] [Accepted: 02/26/2013] [Indexed: 10/27/2022]
Abstract
BACKGROUND Myoclonus-dystonia (MD) is a movement disorder characterized by myoclonic jerks, dystonic postures and psychiatric co-morbidity. A mutation in the DYT11 gene underlies half of MD cases. We hypothesize that MD results from a dysfunctional basal ganglia network causing insufficient inhibitory motor control. To test this hypothesis functional MRI (fMRI) was performed using a validated "Go/No go" task, in order to localize blood-oxygen-level dependence (BOLD) effects corresponding to Response Inhibition (RI). METHODS Twenty-four MD patients (fifteen DYT11 positive) and 24 matched controls responded with a button press to Go (Go-Response) or No go (referred to as 'Stop') cues, resulting in analyses of accurate response suppression to Stop cues (Stop-Inhibit), and incorrect responses to Go cues (Go-Inhibit), or to Stop cues (Stop-Response). RESULTS Response accuracy in patients was impaired due to frequent Go-Inhibit errors. Image analysis of the Stop-Inhibit contrast demonstrated frontal, caudate and cingular activity in both groups. Compared to controls, MD patients showed increased primary motor cortex and insular activation. During Go-Inhibit trials, patients revealed increased activity in the contralateral thalamus (ventral lateral nucleus) and dorso-lateral-prefrontal cortex. In a post-hoc analysis comparing MD patients, DYT11 positive patients demonstrated anterior cerebellum hyperactivation on all contrasts and increased putaminal activation in the Stop-Response contrast. CONCLUSIONS This study demonstrates a distinct association of motor symptoms in MD with the ventral lateral nucleus of the thalamus. Cerebellar dysfunction distinguishes DYT11 positive from negative patients. We suggest that MD might be best considered as a disorder of the cortico-ponto-cerebello-thalamo-cortical system.
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Affiliation(s)
- Sandra M A van der Salm
- Department of Neurology and Clinical Neurophysiology of the Academic Medical Center, Amsterdam, The Netherlands
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13
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Tassone A, Sciamanna G, Bonsi P, Martella G, Pisani A. Experimental Models of Dystonia. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2011; 98:551-72. [DOI: 10.1016/b978-0-12-381328-2.00020-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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14
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Gruber D, Kühn AA, Schoenecker T, Kivi A, Trottenberg T, Hoffmann KT, Gharabaghi A, Kopp UA, Schneider GH, Klein C, Asmus F, Kupsch A. Pallidal and thalamic deep brain stimulation in myoclonus-dystonia. Mov Disord 2010; 25:1733-43. [PMID: 20623686 DOI: 10.1002/mds.23312] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Deep brain stimulation (DBS) of the internal globus pallidus (GPi) and ventral intermediate thalamic nucleus (VIM) are established treatment options in primary dystonia and tremor syndromes and have been reported anecdotally to be efficacious in myoclonus-dystonia (MD). We investigated short- and long-term effects on motor function, cognition, affective state, and quality of life (QoL) of GPi- and VIM-DBS in MD. Ten MD-patients (nine epsilon-sarcoglycan-mutation-positive) were evaluated pre- and post-surgically following continuous bilateral GPi- and VIM-DBS at four time points: presurgical, 6, 12, and as a last follow-up at a mean of 62.3 months postsurgically, and in OFF-, GPi-, VIM-, and GPi-VIM-DBS conditions by validated motor [unified myoclonus rating scale (UMRS), TSUI Score, Burke-Fahn-Marsden dystonia rating scale (BFMDRS)], cognitive, affective, and QoL-scores. MD-symptoms significantly improved at 6 months post-surgery (UMRS: 61.5%, TSUI Score: 36.5%, BFMDRS: 47.3%). Beneficial effects were sustained at long-term evaluation post-surgery (UMRS: 65.5%, TSUI Score: 35.1%, BFMDRS: 48.2%). QoL was significantly ameliorated; affective status and cognition remained unchanged postsurgically irrespective of the stimulation conditions. No serious long-lasting stimulation-related adverse events (AEs) were observed. Both GPi- and VIM-DBS offer equally effective and safe treatment options for MD. With respect to fewer adverse, stimulation-induced events of GPi-DBS in comparison with VIM-DBS, GPi-DBS seems to be preferable. Combined GPi-VIM-DBS can be useful in cases of incapaciting myoclonus, refractory to GPi-DBS alone.
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Affiliation(s)
- Doreen Gruber
- Departments of Neurology, University Medicine Berlin, Berlin, Germany
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15
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Bostan AC, Strick PL. The cerebellum and basal ganglia are interconnected. Neuropsychol Rev 2010; 20:261-70. [PMID: 20811947 DOI: 10.1007/s11065-010-9143-9] [Citation(s) in RCA: 234] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Accepted: 08/22/2010] [Indexed: 11/28/2022]
Abstract
The cerebellum and the basal ganglia are major subcortical nuclei that control multiple aspects of behavior largely through their interactions with the cerebral cortex. Discrete multisynaptic loops connect both the cerebellum and the basal ganglia with multiple areas of the cerebral cortex. Interactions between these loops have traditionally been thought to occur mainly at the level of the cerebral cortex. Here, we review a series of recent anatomical studies in nonhuman primates that challenge this perspective. We show that the anatomical substrate exists for substantial interactions between the cerebellum and the basal ganglia. Furthermore, we discuss how these pathways may provide a useful framework for understanding cerebellar contributions to the manifestation of two prototypical basal ganglia disorders, Parkinson's disease and dystonia.
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Affiliation(s)
- Andreea C Bostan
- Center for the Neural Basis of Cognition, Systems Neuroscience Institute, and Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
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16
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Abstract
PURPOSE OF REVIEW In the past 18 months, several important studies in neuroimaging, epidemiology of dystonia and animal models have been published. Moreover, new advances in genetics have broadened the spectrum of dystonia. Here, we discuss these findings and their implication in the pathophysiology of dystonia. RECENT FINDINGS From neurophysiological studies and animal models, converging arguments support the role of combined corticostriatal, cerebellar and dopaminergic dysfunctions in the pathophysiology of dystonia. A large study in epidemiology identified several risk factors associated with writer's cramp (time spent handwriting each day and the additional burden of an abrupt increase in the writing time in the year before onset). Important studies on the abnormal structure-function relationship in hereditary and sporadic dystonia explored the relationship between genotype, phenotype and endophenotype. SUMMARY Different pathophysiological mechanisms may underlie similar phenotypes whereas different genotypes may share similar functional abnormalities. The respective roles of corticostriatal-cortical and cerebellar loops remain to be clarified as the original causative process (either degenerative or developmental) is accompanied by functional reorganization.
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17
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Primate models of dystonia. Prog Neurobiol 2009; 87:118-31. [DOI: 10.1016/j.pneurobio.2008.10.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 10/14/2008] [Accepted: 10/31/2008] [Indexed: 11/18/2022]
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QingGeLeTu, Suzuki Y, Kiyosawa M, Ishiwata K, Mochizuki M. Functional and Neuroreceptor Imaging of the Brain in Bicuculline-Induced Dystonic Rats. TOHOKU J EXP MED 2009; 217:313-20. [DOI: 10.1620/tjem.217.313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- QingGeLeTu
- Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology
| | - Yukihisa Suzuki
- Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology
| | - Motohiro Kiyosawa
- Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology
| | - Kiichi Ishiwata
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology
| | - Manabu Mochizuki
- Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University
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Myoclonus and tremor response to thalamic deep brain stimulation parameters in a patient with inherited myoclonus-dystonia syndrome. Clin Neurol Neurosurg 2008; 111:303-6. [PMID: 19081669 DOI: 10.1016/j.clineuro.2008.10.015] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 09/16/2008] [Accepted: 10/26/2008] [Indexed: 11/20/2022]
Abstract
We present a 74-year-old woman with inherited myoclonus-dystonia, with predominant myoclonus and a novel mutation in the epsilon-sarcoglycan gene. The patient reports a life-long history of rapid, jerking movements, most severe in the upper extremities as well as a postural and action tremor. Bilateral deep brain stimulation (DBS) of the ventral intermediate nucleus of the thalamus was performed, and the patient demonstrated moderate clinical improvement in myoclonus. We studied the effects on myoclonus and tremor of varying DBS frequency and amplitude. The frequency tuning curve for myoclonus was similar to that of tremor, suggesting similar mechanisms by which DBS alleviates both disorders.
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Galvan A, Wichmann T. GABAergic circuits in the basal ganglia and movement disorders. PROGRESS IN BRAIN RESEARCH 2007; 160:287-312. [PMID: 17499121 DOI: 10.1016/s0079-6123(06)60017-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
GABA is the major inhibitory neurotransmitter in the basal ganglia, and GABAergic pathways dominate information processing in most areas of these structures. It is therefore not surprising that abnormalities of GABAergic transmission are key elements in pathophysiologic models of movement disorders involving the basal ganglia. These include hypokinetic diseases such as Parkinson's disease, and hyperkinetic diseases, such as Huntington's disease or hemiballism. In this chapter, we will briefly review the major anatomic features of the GABAergic pathways in the basal ganglia, and then describe in greater detail the changes of GABAergic transmission, which are known to occur in movement disorders.
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Affiliation(s)
- Adriana Galvan
- Department of Neurology, School of Medicine and Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA.
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Cadotte AJ, DeMarse TB. Poly-HEMA as a drug delivery device for in vitro neural networks on micro-electrode arrays. J Neural Eng 2005; 2:114-22. [PMID: 16317235 DOI: 10.1088/1741-2560/2/4/007] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Delivery of pharmacological agents in vitro can often be a difficult, time consuming and costly process. In this paper, we describe an economical method for in vitro delivery using a hydrogel of poly hydroxyethyl methacrylate (PHEMA) that can absorb up to 50% of its weight of any water-solubilized pharmacological agent. This agent will then passively diffuse into surrounding media upon application in vitro. An in vitro test of PHEMA as a drug delivery device was conducted using dissociated rat-cortical neurons cultured on micro-electrode arrays. These micro-electrode arrays permit the real-time measurement of neural activity at 60 different sites across a network of neurons. Neural activity was compared during the application of PHEMA saturated with cell culture media and PHEMA saturated with bicuculline, a widely used pharmacological agent with stereotypical effects on neural activity patterns. Application of PHEMA saturated with bicuculline produced a gradual increase in concentration in vitro. When the minimum effective concentration of bicuculline was reached, which was found to be 0.59 microM using the diffusion properties of PHEMA, it produced the rapid almost periodic synchronized bursting characteristically associated with this agent. In contrast, the application of PHEMA saturated in culture media alone had no effect on neural activity reinforcing its inherent inert properties. Since PHEMA is nontoxic, can be molded into a variety of shapes, quickly manufactured in any laboratory and is inexpensive to produce, the material represents a promising alternative to drug delivery systems on the market today.
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Affiliation(s)
- Alex J Cadotte
- Department of Biomedical Engineering, University of Florida, 147 Biomedical Engineering Building, Box 116131, Gainesville, FL, USA
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Abstract
We describe an uncommon movement disorder after stroke. A 70-year-old man was admitted for a right thalamic haemorrhage and 1 week later developed bilateral contractions of the face. Electromyographic study revealed a bilateral facial dystonia. The association of this bilateral facial dystonia and vertical gaze palsy produced the aspect of a "risus sardonicus."
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Affiliation(s)
- Igor Sibon
- Fédération de Neurosciences Cliniques, Centre Hospitalier Universitaire Bordeaux, Bordeaux, France
| | - Pierre Burbaud
- Fédération de Neurosciences Cliniques, Centre Hospitalier Universitaire Bordeaux, Bordeaux, France
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23
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Abstract
A decreased activity of basal ganglia output neurons is thought to underlie idiopathic dystonias and other hyperkinetic movement disorders. We found recently a reduced spontaneous discharge rate of entopeduncular neurons (internal globus pallidus in primates) in dt(sz) hamsters, an unique model for idiopathic paroxysmal dystonia in which stress-inducible attacks show an age-dependent severity. Otherwise, it has been suggested that an altered discharge pattern may be more important for the occurrence of dystonia than a reduced discharge rate. Based on qualitative and computerized quantitative evaluations of interspike interval histograms and spike trains of extracellularly recorded single neurons, we investigated the spontaneous discharge pattern of GABAergic entopeduncular and nigral neurons in dt(sz) hamsters at different ages. The discharge pattern of entopeduncular neurons was highly irregular and showed an altered burst-like firing in dt(sz) hamsters at the age of the most marked expression of dystonia when compared with age-matched nondystonic controls. In line with a recently reported normalization of discharge rates after age-dependent disappearance of dystonia, we found an almost complete normalization of the discharge pattern of entopeduncular neurons after remission of dystonia in dt(sz) hamsters. Investigations of GABAergic nigral neurons, reported recently to have the same spontaneous discharge rates in dystonic and nondystonic hamsters, did not show an altered firing pattern in dt(sz) hamsters. The present data clearly indicate the fundamental importance of an altered discharge pattern of entopeduncular neurons for the expression of paroxysmal dystonia, and probably also for other dyskinesias, and may explain the improvements obtained by pallidotomy in dystonic patients despite an obviously reduced pallidal output.
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Macia F, Escola L, Guehl D, Michelet T, Bioulac B, Burbaud P. Neuronal activity in the monkey motor thalamus during bicuculline-induced dystonia. Eur J Neurosci 2002; 15:1353-62. [PMID: 11994129 DOI: 10.1046/j.1460-9568.2002.01964.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recent data suggest that a decreased basal ganglia output may occur in dystonia, resulting in an increased thalamic drive to the mesial premotor cortex. In a previous work we found that injection of the GABAA antagonist bicuculline into the rostral motor thalamus induced contralateral dystonic postures, whereas myoclonic jerks were frequent after injection into the caudal motor thalamus. In the present study, we performed electrophysiological recordings in the rostral and caudal parts of the ventrolateral thalamus of two cynomolgus monkeys before and after bicuculline injections or saline injections. Discharge frequencies of thalamic neurons were increased after bicuculline injections vs. controls. Their discharge pattern was more bursty in the caudal part in which bursts of neuronal activity were correlated with myoclonic jerks. After bicuculline injection, neurons responded more frequently and less selectively to passive limb movements in both parts of the motor thalamus. Conversely, the response to microstimulation increased after bicuculline injection, particularly in the caudal part. Our data show that acute bicuculline-induced dystonia is associated with a reversible overactivity and disorganization of neuronal activity in the motor thalamus. Such a phenomenon might induce an overspreading of cortical activity leading to dystonia. We postulate that the distinct clinical syndromes observed after bicuculline injections into the rostral and caudal motor thalamus are due to differences both in the neuronal circuitry within each thalamic nucleus and in segregated cortical projections.
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Affiliation(s)
- F Macia
- Laboratoire de Neurophysiologie, UMR CNRS 5543, Université Victor Segalen Bordeaux 2, 146, rue Léo Saignat 33076 Bordeaux, France
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