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Sohns E, Szmulewicz DJ, Tarnutzer AA. Oculomotor and Vestibular Deficits in Friedreich Ataxia - Systematic Review and Meta-Analysis of Quantitative Measurements. CEREBELLUM (LONDON, ENGLAND) 2024:10.1007/s12311-024-01716-8. [PMID: 39066865 DOI: 10.1007/s12311-024-01716-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/25/2024] [Indexed: 07/30/2024]
Abstract
Disease-specific oculomotor assessments play a crucial role in the early diagnosis of hereditary cerebellar ataxias. Whereas several studies have reported on quantitative oculomotor and vestibular measurements in Friedreich's Ataxia (FRDA), the value of specific oculomotor paradigms remains unclear. We aimed to address this knowledge gap through a systematic literature review and providing disease-specific recommendations for a tailored set of eye-movement recordings in FRDA. MEDLINE and Embase were searched for studies reporting on quantitative oculomotor and/or vestibular measurements in FRDA-patients. Data on oculomotor and vestibular parameters were extracted and correlations with a range of clinical parameters were sought. Included studies (n = 17) reported on 185 patients. Abnormalities observed included the presence of saccadic intrusions (143/161) such as square-wave jerks (SWJ, 90/109) and ocular flutter (21/43), impaired eccentric gaze-holding (40/104), abnormal pursuit (81/93) and angular vestibulo-ocular reflex (aVOR) deficits (39/48). For visually-guided saccades (VGS), we frequently observed increases in saccade latency (27/38) and dysmetric saccades (71/93), whereas saccade velocity was more often preserved (37/43). Augmented anti-saccade (AS) latency, downbeat nystagmus and frequent macro-SWJ correlated with disease duration. Increased AS-latency and VGS-latency, frequent macro-SWJ, reduced aVOR-gain and augmented aVOR peak-latency correlated with disease severity. A broad range of oculomotor and vestibular deficits are documented in the literature. Impairments in pursuit, saccades and aVOR-responses are most commonly reported, and as such, should be prioritized as disease markers. Quantitative oculomotor testing in FRDA may facilitate early diagnosis and prove valuable in monitoring disease progression and treatment response.
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Affiliation(s)
- E Sohns
- Faculty of Medicine, University of Zurich, Zurich, Switzerland
| | - D J Szmulewicz
- Balance Disorders & Ataxia Service, Royal Victorian Eye and Ear Hospital, Melbourne, VIC, Australia
- The Bionics Institute, Melbourne, VIC, Australia
- University of Melbourne AU, Melbourne, VIC, Australia
| | - A A Tarnutzer
- Faculty of Medicine, University of Zurich, Zurich, Switzerland.
- Neurology, Cantonal Hospital of Baden, Im Ergel 1, Baden, 5404, Switzerland.
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Garces P, Antoniades CA, Sobanska A, Kovacs N, Ying SH, Gupta AS, Perlman S, Szmulewicz DJ, Pane C, Németh AH, Jardim LB, Coarelli G, Dankova M, Traschütz A, Tarnutzer AA. Quantitative Oculomotor Assessment in Hereditary Ataxia: Discriminatory Power, Correlation with Severity Measures, and Recommended Parameters for Specific Genotypes. CEREBELLUM (LONDON, ENGLAND) 2024; 23:121-135. [PMID: 36640220 PMCID: PMC10864420 DOI: 10.1007/s12311-023-01514-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/09/2023] [Indexed: 01/15/2023]
Abstract
Characterizing bedside oculomotor deficits is a critical factor in defining the clinical presentation of hereditary ataxias. Quantitative assessments are increasingly available and have significant advantages, including comparability over time, reduced examiner dependency, and sensitivity to subtle changes. To delineate the potential of quantitative oculomotor assessments as digital-motor outcome measures for clinical trials in ataxia, we searched MEDLINE for articles reporting on quantitative eye movement recordings in genetically confirmed or suspected hereditary ataxias, asking which paradigms are most promising for capturing disease progression and treatment response. Eighty-nine manuscripts identified reported on 1541 patients, including spinocerebellar ataxias (SCA2, n = 421), SCA3 (n = 268), SCA6 (n = 117), other SCAs (n = 97), Friedreich ataxia (FRDA, n = 178), Niemann-Pick disease type C (NPC, n = 57), and ataxia-telangiectasia (n = 85) as largest cohorts. Whereas most studies reported discriminatory power of oculomotor assessments in diagnostics, few explored their value for monitoring genotype-specific disease progression (n = 2; SCA2) or treatment response (n = 8; SCA2, FRDA, NPC, ataxia-telangiectasia, episodic-ataxia 4). Oculomotor parameters correlated with disease severity measures including clinical scores (n = 18 studies (SARA: n = 9)), chronological measures (e.g., age, disease duration, time-to-symptom onset; n = 17), genetic stratification (n = 9), and imaging measures of atrophy (n = 5). Recurrent correlations across many ataxias (SCA2/3/17, FRDA, NPC) suggest saccadic eye movements as potentially generic quantitative oculomotor outcome. Recommendation of other paradigms was limited by the scarcity of cross-validating correlations, except saccadic intrusions (FRDA), pursuit eye movements (SCA17), and quantitative head-impulse testing (SCA3/6). This work aids in understanding the current knowledge of quantitative oculomotor parameters in hereditary ataxias, and identifies gaps for validation as potential trial outcome measures in specific ataxia genotypes.
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Affiliation(s)
- Pilar Garces
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases, Roche Innovation Center Basel, Basel, Switzerland
| | - Chrystalina A Antoniades
- NeuroMetrology Lab, Nuffield Department of Clinical Neurosciences, Medical Sciences Division, University of Oxford, Oxford, OX3 9DU, UK
| | - Anna Sobanska
- Department of Clinical Neurophysiology, Institute of Psychiatry and Neurology, Warsaw, Poland
| | - Norbert Kovacs
- Department of Neurology, Medical School, University of Pecs, Pecs, Hungary
| | - Sarah H Ying
- Department of Otology and Laryngology and Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Anoopum S Gupta
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Susan Perlman
- University of California Los Angeles, Los Angeles, CA, USA
| | - David J Szmulewicz
- Balance Disorders and Ataxia Service, Royal Victoria Eye and Ear Hospital, East Melbourne, Melbourne, VIC, 3002, Australia
- The Florey Institute of Neuroscience and Mental Health, Parkville, Melbourne, VIC, 3052, Australia
| | - Chiara Pane
- Department of Neurosciences and Reproductive and Odontostomatological Sciences, University of Naples "Federico II", Naples, Italy
| | - Andrea H Németh
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Laura B Jardim
- Departamento de Medicina Interna, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Serviço de Genética Médica/Centro de Pesquisa Clínica e Experimental, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Giulia Coarelli
- Institut du Cerveau-Paris Brain Institute-ICM, Inserm U1127, CNRS UMR7225, Sorbonne Université, Paris, France
- Department of Genetics, Neurogene National Reference Centre for Rare Diseases, Pitié-Salpêtrière University Hospital, Assistance Publique, Hôpitaux de Paris, Paris, France
| | - Michaela Dankova
- Department of Neurology, Centre of Hereditary Ataxias, 2nd Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic
| | - Andreas Traschütz
- Research Division "Translational Genomics of Neurodegenerative Diseases," Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen, Germany
| | - Alexander A Tarnutzer
- Cantonal Hospital of Baden, Baden, Switzerland.
- Faculty of Medicine, University of Zurich, Zurich, Switzerland.
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Tanaka M, Kunimatsu J, Suzuki TW, Kameda M, Ohmae S, Uematsu A, Takeya R. Roles of the Cerebellum in Motor Preparation and Prediction of Timing. Neuroscience 2021; 462:220-234. [DOI: 10.1016/j.neuroscience.2020.04.039] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 04/10/2020] [Accepted: 04/21/2020] [Indexed: 12/19/2022]
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Distractor Inhibition in Autism Spectrum Disorder: Evidence of a Selective Impairment for Individuals with Co-occurring Motor Difficulties. J Autism Dev Disord 2018; 49:669-682. [DOI: 10.1007/s10803-018-3744-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Superior Visual Search and Crowding Abilities Are Not Characteristic of All Individuals on the Autism Spectrum. J Autism Dev Disord 2018; 48:3499-3512. [DOI: 10.1007/s10803-018-3601-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Pretegiani E, Piu P, Rosini F, Federighi P, Serchi V, Tumminelli G, Dotti MT, Federico A, Rufa A. Anti-Saccades in Cerebellar Ataxias Reveal a Contribution of the Cerebellum in Executive Functions. Front Neurol 2018; 9:274. [PMID: 29740392 PMCID: PMC5926529 DOI: 10.3389/fneur.2018.00274] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 04/06/2018] [Indexed: 01/25/2023] Open
Abstract
OBJECTIVE Increasing evidence suggests a cerebellar contribution to modulate cognitive aspects of motor behavior and executive functions. Supporting findings come from studies on patients with neurodegenerative diseases, in which however, given the extent of the disease, the specific role of the cerebellum, could not be clearly isolated. Anti-saccades are considered a sensitive tool to test executive functions. The anti-saccade underlying neural network, consisting of different cortical areas and their downstream connections including the lateral cerebellum, has been largely clarified. To separate the role of the cerebellum with respect to other cortical structures in executive control, we compared the anti-saccade performances in two distinct cohorts of patients with cerebellar disorders (with and without cerebral cortical involvement). METHODS Eye movements during the execution of anti-saccades were recorded in 12 patients with spinocerebellar ataxia type 2 (a cortical-subcortical neurodegenerative disease), 10 patients with late onset cerebellar ataxia (an isolated cerebellar atrophy), and 34 matched controls. RESULTS In the anti-saccade task, besides dynamic changes already demonstrated in the pro-saccades of these patients, we found in both groups of cerebellar patients prolonged latency with larger variability than normal and increased directional error rate. Errors, however, were corrected by cerebellar patients as frequently as normal. No significant differences were found in patients with and without cortical involvement. CONCLUSION Our results indicate, in a large cohort of cerebellar patients, that the cerebellum plays a critical role in the regulation of executive motor control not only, as well known, by controlling the end of a movement, but also modulating its initiation and reducing reflexive responses that would perturb voluntary actions.
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Affiliation(s)
- Elena Pretegiani
- Eye-Tracking and Visual Application Laboratory (EVALab), Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, United States
| | - Pietro Piu
- Eye-Tracking and Visual Application Laboratory (EVALab), Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
| | - Francesca Rosini
- Eye-Tracking and Visual Application Laboratory (EVALab), Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Neurological and Neurometabolic Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
| | - Pamela Federighi
- Eye-Tracking and Visual Application Laboratory (EVALab), Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Department of Business and Law, University of Siena, Siena, Italy
| | - Valeria Serchi
- Eye-Tracking and Visual Application Laboratory (EVALab), Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
| | - Gemma Tumminelli
- Eye-Tracking and Visual Application Laboratory (EVALab), Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Neurological and Neurometabolic Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
| | - Maria Teresa Dotti
- Neurological and Neurometabolic Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
| | - Antonio Federico
- Neurological and Neurometabolic Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
| | - Alessandra Rufa
- Eye-Tracking and Visual Application Laboratory (EVALab), Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Neurological and Neurometabolic Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
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Implications of Lateral Cerebellum in Proactive Control of Saccades. J Neurosci 2017; 36:7066-74. [PMID: 27358462 DOI: 10.1523/jneurosci.0733-16.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 05/25/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Although several lines of evidence establish the involvement of the medial and vestibular parts of the cerebellum in the adaptive control of eye movements, the role of the lateral hemisphere of the cerebellum in eye movements remains unclear. Ascending projections from the lateral cerebellum to the frontal and parietal association cortices via the thalamus are consistent with a role of these pathways in higher-order oculomotor control. In support of this, previous functional imaging studies and recent analyses in subjects with cerebellar lesions have indicated a role for the lateral cerebellum in volitional eye movements such as anti-saccades. To elucidate the underlying mechanisms, we recorded from single neurons in the dentate nucleus of the cerebellum in monkeys performing anti-saccade/pro-saccade tasks. We found that neurons in the posterior part of the dentate nucleus showed higher firing rates during the preparation of anti-saccades compared with pro-saccades. When the animals made erroneous saccades to the visual stimuli in the anti-saccade trials, the firing rate during the preparatory period decreased. Furthermore, local inactivation of the recording sites with muscimol moderately increased the proportion of error trials, while successful anti-saccades were more variable and often had shorter latency during inactivation. Thus, our results show that neuronal activity in the cerebellar dentate nucleus causally regulates anti-saccade performance. Neuronal signals from the lateral cerebellum to the frontal cortex might modulate the proactive control signals in the corticobasal ganglia circuitry that inhibit early reactive responses and possibly optimize the speed and accuracy of anti-saccades. SIGNIFICANCE STATEMENT Although the lateral cerebellum is interconnected with the cortical eye fields via the thalamus and the pons, its role in eye movements remains unclear. We found that neurons in the caudal part of the lateral (dentate) nucleus of the cerebellum showed the increased firing rate during the preparation of anti-saccades. Inactivation of the recording sites modestly elevated the rate of erroneous saccades to the visual stimuli in the anti-saccade trials, while successful anti-saccades during inactivation tended to have a shorter latency. Our data indicate that neuronal signals in the lateral cerebellum may proactively regulate anti-saccade generation through the pathways to the frontal cortex, and may inhibit early reactive responses and regulate the accuracy of anti-saccades.
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8
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Harding IH, Corben LA, Storey E, Egan GF, Stagnitti MR, Poudel GR, Delatycki MB, Georgiou-Karistianis N. Fronto-cerebellar dysfunction and dysconnectivity underlying cognition in friedreich ataxia: The IMAGE-FRDA study. Hum Brain Mapp 2015; 37:338-50. [PMID: 26502936 DOI: 10.1002/hbm.23034] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 09/16/2015] [Accepted: 10/12/2015] [Indexed: 12/22/2022] Open
Abstract
Friedreich ataxia (FRDA) is a progressive neurodegenerative disorder defined by pathology within the cerebellum and spinal tracts. Although FRDA is most readily linked to motor and sensory dysfunctions, reported impairments in working memory and executive functions indicate that abnormalities may also extend to associations regions of the cerebral cortex and/or cerebello-cerebral interactions. To test this hypothesis, 29 individuals with genetically confirmed FRDA and 34 healthy controls performed a verbal n-back working memory task while undergoing functional magnetic resonance imaging. No significant group differences were evident in task performance. However, individuals with FRDA had deficits in brain activations both in the lateral cerebellar hemispheres, principally encompassing lobule VI, and the prefrontal cortex, including regions of the anterior insular and rostrolateral prefrontal cortices. Functional connectivity between these brain regions was also impaired, supporting a putative link between primary cerebellar dysfunction and subsequent cerebral abnormalities. Disease severity and genetic markers of disease liability were correlated specifically with cerebellar dysfunction, while correlations between behavioural performance and both cerebral activations and cerebello-cerebral connectivity were observed in controls, but not in the FRDA cohort. Taken together, these findings support a diaschisis model of brain dysfunction, whereby primary disease effects in the cerebellum result in functional changes in downstream fronto-cerebellar networks. These fronto-cerebellar disturbances provide a putative biological basis for the nonmotor symptoms observed in FRDA, and reflect the consequence of localized cerebellar pathology to distributed brain function underlying higher-order cognition.
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Affiliation(s)
- Ian H Harding
- School of Psychological Sciences, Monash University, Melbourne, Australia
| | - Louise A Corben
- School of Psychological Sciences, Monash University, Melbourne, Australia.,Bruce Lefroy Centre, Murdoch Childrens Research Institute, Melbourne, Australia.,Friedreich Ataxia Clinic, Monash Medical Centre, Monash Health, Melbourne, Australia
| | - Elsdon Storey
- Department of Medicine, Monash University, Melbourne, Australia
| | - Gary F Egan
- Monash Biomedical Imaging, Monash University, Melbourne, Australia
| | | | - Govinda R Poudel
- School of Psychological Sciences, Monash University, Melbourne, Australia
| | - Martin B Delatycki
- School of Psychological Sciences, Monash University, Melbourne, Australia.,Bruce Lefroy Centre, Murdoch Childrens Research Institute, Melbourne, Australia.,Department of Clinical Genetics, Austin Health, Melbourne, Australia
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Fielding J, Clough M, Beh S, Millist L, Sears D, Frohman AN, Lizak N, Lim J, Kolbe S, Rennaker RL, Frohman TC, White OB, Frohman EM. Ocular motor signatures of cognitive dysfunction in multiple sclerosis. Nat Rev Neurol 2015; 11:637-45. [PMID: 26369516 DOI: 10.1038/nrneurol.2015.174] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The anatomical and functional overlap between ocular motor command circuitry and the higher-order networks that form the scaffolding for cognition makes for a compelling hypothesis that measures of ocular motility could provide a means to sensitively interrogate cognitive dysfunction in people with multiple sclerosis (MS). Such an approach may ultimately provide objective and reproducible measures of cognitive dysfunction that offer an innovative capability to refine diagnosis, improve prognostication, and more accurately codify disease burden. A further dividend may be the validation and application of biomarkers that can be used in studies aimed at identifying and monitoring preventative, protective and even restorative properties of novel neurotherapeutics in MS. This Review discusses the utility of ocular motor measures in patients with MS to characterize disruption to wide-ranging networks that support cognitive function.
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Affiliation(s)
- Joanne Fielding
- School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Wellington Road, Clayton, VIC 3800, Australia.,Department of Medicine, Royal Melbourne Hospital, Melbourne Brain Centre, University of Melbourne, Parkville, VIC 3050, Australia
| | - Meaghan Clough
- School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Shin Beh
- Departments of Neurology and Neurotherapeutics, University of Texas Southwestern School of Medicine, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Lynette Millist
- Department of Medicine, Royal Melbourne Hospital, Melbourne Brain Centre, University of Melbourne, Parkville, VIC 3050, Australia
| | - Derek Sears
- Departments of Neurology and Neurotherapeutics, University of Texas Southwestern School of Medicine, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Ashley N Frohman
- Departments of Neurology and Neurotherapeutics, University of Texas Southwestern School of Medicine, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Nathaniel Lizak
- Monash School of Medicine, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Jayne Lim
- Department of Medicine, Royal Melbourne Hospital, Melbourne Brain Centre, University of Melbourne, Parkville, VIC 3050, Australia
| | - Scott Kolbe
- Department of Anatomy and Neuroscience, Medical Building, University of Melbourne, Parkville, VIC 3010, Australia
| | - Robert L Rennaker
- Department of Bioengineering and Computer Science, University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, USA
| | - Teresa C Frohman
- Departments of Neurology and Neurotherapeutics, University of Texas Southwestern School of Medicine, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Owen B White
- Department of Medicine, Royal Melbourne Hospital, Melbourne Brain Centre, University of Melbourne, Parkville, VIC 3050, Australia
| | - Elliot M Frohman
- Departments of Neurology and Neurotherapeutics, University of Texas Southwestern School of Medicine, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.,Department of Bioengineering and Computer Science, University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080, USA
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Batson MA, Petridou N, Klomp DWJ, Frens MA, Neggers SFW. Single session imaging of cerebellum at 7 Tesla: obtaining structure and function of multiple motor subsystems in individual subjects. PLoS One 2015; 10:e0134933. [PMID: 26259014 PMCID: PMC4530960 DOI: 10.1371/journal.pone.0134933] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 07/15/2015] [Indexed: 12/11/2022] Open
Abstract
The recent increase in the use of high field MR systems is accompanied by a demand for acquisition techniques and coil systems that can take advantage of increased power and accuracy without being susceptible to increased noise. Physical location and anatomical complexity of targeted regions must be considered when attempting to image deeper structures with small nuclei and/or complex cytoarchitechtonics (i.e. small microvasculature and deep nuclei), such as the brainstem and the cerebellum (Cb). Once these obstacles are overcome, the concomitant increase in signal strength at higher field strength should allow for faster acquisition of MR images. Here we show that it is technically feasible to quickly and accurately detect blood oxygen level dependent (BOLD) signal changes and obtain anatomical images of Cb at high spatial resolutions in individual subjects at 7 Tesla in a single one-hour session. Images were obtained using two high-density multi-element surface coils (32 channels in total) placed beneath the head at the level of Cb, two channel transmission, and three-dimensional sensitivity encoded (3D, SENSE) acquisitions to investigate sensorimotor activations in Cb. Two classic sensorimotor tasks were used to detect Cb activations. BOLD signal changes during motor activity resulted in concentrated clusters of activity within the Cb lobules associated with each task, observed consistently and independently in each subject: Oculomotor vermis (VI/VII) and CrusI/II for pro- and anti-saccades; ipsilateral hemispheres IV-VI for finger tapping; and topographical separation of eye- and hand- activations in hemispheres VI and VIIb/VIII. Though fast temporal resolution was not attempted here, these functional patches of highly specific BOLD signal changes may reflect small-scale shunting of blood in the microvasculature of Cb. The observed improvements in acquisition time and signal detection are ideal for individualized investigations such as differentiation of functional zones prior to surgery.
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Affiliation(s)
- Melissa A. Batson
- Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands
- Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands
- * E-mail:
| | - Natalia Petridou
- Radiology Department, Imaging Division, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Dennis W. J. Klomp
- Radiology Department, Imaging Division, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Maarten A. Frens
- Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands
- Erasmus University College, Rotterdam, The Netherlands
| | - Sebastiaan F. W. Neggers
- Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands
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11
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Evans-Galea MV, Pébay A, Dottori M, Corben LA, Ong SH, Lockhart PJ, Delatycki MB. Cell and gene therapy for Friedreich ataxia: progress to date. Hum Gene Ther 2014; 25:684-93. [PMID: 24749505 DOI: 10.1089/hum.2013.180] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Neurodegenerative disorders such as Friedreich ataxia (FRDA) present significant challenges in developing effective therapeutic intervention. Current treatments aim to manage symptoms and thus improve quality of life, but none can cure, nor are proven to slow, the neurodegeneration inherent to this disease. The primary clinical features of FRDA include progressive ataxia and shortened life span, with complications of cardiomyopathy being the major cause of death. FRDA is most commonly caused by an expanded GAA trinucleotide repeat in the first intron of FXN that leads to reduced levels of frataxin, a mitochondrial protein important for iron metabolism. The GAA expansion in FRDA does not alter the coding sequence of FXN. It results in reduced production of structurally normal frataxin, and hence any increase in protein level is expected to be therapeutically beneficial. Recently, there has been increased interest in developing novel therapeutic applications like cell and/or gene therapies, and these cutting-edge applications could provide effective treatment options for FRDA. Importantly, since individuals with FRDA produce frataxin at low levels, increased expression should not elicit an immune response. Here we review the advances to date and highlight the future potential for cell and gene therapy to treat this debilitating disease.
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Affiliation(s)
- Marguerite V Evans-Galea
- 1 Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute , Parkville Victoria 3052, Australia
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Schwabova J, Maly T, Laczo J, Zumrova A, Komarek V, Musova Z, Zahalka F. Application of a Scale for the Assessment and Rating of Ataxia (SARA) in Friedreich's ataxia patients according to posturography is limited. J Neurol Sci 2014; 341:64-7. [DOI: 10.1016/j.jns.2014.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 03/28/2014] [Accepted: 04/01/2014] [Indexed: 10/25/2022]
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Saccade reprogramming in Friedreich ataxia reveals impairments in the cognitive control of saccadic eye movement. Brain Cogn 2014; 87:161-7. [PMID: 24752035 DOI: 10.1016/j.bandc.2014.03.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 01/14/2014] [Accepted: 03/30/2014] [Indexed: 12/22/2022]
Abstract
Although cerebellar dysfunction has known effects on motor function in Friedreich ataxia (FRDA), it remains unclear the extent to which the reprogramming of eye movements (saccades) and inhibition of well-learned automatic responses are similarly compromised in affected individuals. Here we examined saccade reprogramming to assess the ability of people with FRDA to respond toward unexpected changes in either the amplitude or direction of an "oddball" target. Thirteen individuals with genetically confirmed FRDA and 12 age-matched controls participated in the study. The saccade reprogramming paradigm was used to examine the effect of an unpredictable "oddball" target on saccade latencies and accuracy when compared to a well-learned sequence of reciprocating movements. Horizontal eye movements were recorded using a scleral search coil eye tracking technique. The results showed a proportionally greater increase in latencies for reprogrammed saccades toward an oddball-direction target in the FRDA group when compared to controls. The FRDA group were also less accurate in primary saccade gain (i.e. ratio of saccade amplitude to target amplitude) when reprogramming saccades toward an unexpected change in direction. No significant group differences were found on any of the oddball-amplitude targets. Significant correlations were revealed between latency and disease severity as measured by the Friedreich Ataxia Rating Scale. These findings provide further support to the view that cognitive changes in FRDA may arise from disruption of cerebellar connections to cortical structures.
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Panouillères M, Frismand S, Sillan O, Urquizar C, Vighetto A, Pélisson D, Tilikete C. Saccades and eye-head coordination in ataxia with oculomotor apraxia type 2. THE CEREBELLUM 2014; 12:557-67. [PMID: 23475383 DOI: 10.1007/s12311-013-0463-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Ataxia with oculomotor apraxia type 2 (AOA2) is one of the most frequent autosomal recessive cerebellar ataxias. Oculomotor apraxia refers to horizontal gaze failure due to deficits in voluntary/reactive eye movements. These deficits can manifest as increased latency and/or hypometria of saccades with a staircase pattern and are frequently associated with compensatory head thrust movements. Oculomotor disturbances associated with AOA2 have been poorly studied mainly because the diagnosis of oculomotor apraxia was based on the presence of compensatory head thrusts. The aim of this study was to characterise the nature of horizontal gaze failure in patients with AOA2 and to demonstrate oculomotor apraxia even in the absence of head thrusts. Five patients with AOA2, without head thrusts, were tested in saccadic tasks with the head restrained or free to move and their performance was compared to a group of six healthy participants. The most salient deficit of the patients was saccadic hypometria with a typical staircase pattern. Saccade latency in the patients was longer than controls only for memory-guided saccades. In the head-free condition, head movements were delayed relative to the eye and their amplitude and velocity were strongly reduced compared to controls. Our study emphasises that in AOA2, hypometric saccades with a staircase pattern are a more reliable sign of oculomotor apraxia than head thrust movements. In addition, the variety of eye and head movements' deficits suggests that, although the main neural degeneration in AOA2 affects the cerebellum, this disease affects other structures.
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Affiliation(s)
- Muriel Panouillères
- INSERM U1028; CNRS UMR5292; Lyon Neuroscience Research Center, ImpAct Team, Bron, 69676, France.
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15
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Shelton AL, Cornish K, Kraan C, Georgiou-Karistianis N, Metcalfe SA, Bradshaw JL, Hocking DR, Archibald AD, Cohen J, Trollor JN, Fielding J. Exploring inhibitory deficits in female premutation carriers of fragile X syndrome: through eye movements. Brain Cogn 2014; 85:201-8. [PMID: 24424424 DOI: 10.1016/j.bandc.2013.12.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 12/13/2013] [Accepted: 12/17/2013] [Indexed: 01/21/2023]
Abstract
There is evidence which demonstrates that a subset of males with a premutation CGG repeat expansion (between 55 and 200 repeats) of the fragile X mental retardation 1 gene exhibit subtle deficits of executive function that progressively deteriorate with increasing age and CGG repeat length. However, it remains unclear whether similar deficits, which may indicate the onset of more severe degeneration, are evident in female PM-carriers. In the present study we explore whether female PM-carriers exhibit deficits of executive function which parallel those of male PM-carriers. Fourteen female fragile X premutation carriers without fragile X-associated tremor/ataxia syndrome and fourteen age, sex, and IQ matched controls underwent ocular motor and neuropsychological tests of select executive processes, specifically of response inhibition and working memory. Group comparisons revealed poorer inhibitory control for female premutation carriers on ocular motor tasks, in addition to demonstrating some difficulties in behaviour self-regulation, when compared to controls. A negative correlation between CGG repeat length and antisaccade error rates for premutation carriers was also found. Our preliminary findings indicate that impaired inhibitory control may represent a phenotype characteristic which may be a sensitive risk biomarker within this female fragile X premutation population.
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Affiliation(s)
- Annie L Shelton
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Kim Cornish
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Claudine Kraan
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Nellie Georgiou-Karistianis
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Sylvia A Metcalfe
- Genetics Education and Health Research, Murdoch Childrens Research Institute, Flemington Road, Parkville, Victoria 3052, Australia; Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria 3025, Australia
| | - John L Bradshaw
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Darren R Hocking
- Olga Tennison Autism Research Centre, School of Psychological Science, La Trobe University, Bundoora 3086, Australia
| | - Alison D Archibald
- Genetics Education and Health Research, Murdoch Childrens Research Institute, Flemington Road, Parkville, Victoria 3052, Australia; Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria 3025, Australia; Victorian Clinical Genetics Services, Flemington Rd, Parkville, Victoria 3052, Australia
| | - Jonathan Cohen
- Genetics Education and Health Research, Murdoch Childrens Research Institute, Flemington Road, Parkville, Victoria 3052, Australia; Centre for Developmental Disability Health Victoria, Monash University, Clayton, Victoria 3800, Australia; Fragile X Alliance Inc., Clinic and Resource Centre, 263 Glen Eira Road, North Caulfield, Victoria 3161, Australia
| | - Julian N Trollor
- Department of Developmental Disability Neuropsychiatry and Centre for Health Brain Ageing, School of Psychiatry, University of New South Wales, Sydney 2052, Australia
| | - Joanne Fielding
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia.
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16
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Jamadar SD, Fielding J, Egan GF. Quantitative meta-analysis of fMRI and PET studies reveals consistent activation in fronto-striatal-parietal regions and cerebellum during antisaccades and prosaccades. Front Psychol 2013; 4:749. [PMID: 24137150 PMCID: PMC3797465 DOI: 10.3389/fpsyg.2013.00749] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 09/26/2013] [Indexed: 11/18/2022] Open
Abstract
The antisaccade task is a classic task of oculomotor control that requires participants to inhibit a saccade to a target and instead make a voluntary saccade to the mirror opposite location. By comparison, the prosaccade task requires participants to make a visually-guided saccade to the target. These tasks have been studied extensively using behavioral oculomotor, electrophysiological, and neuroimaging in both non-human primates and humans. In humans, the antisaccade task is under active investigation as a potential endophenotype or biomarker for multiple psychiatric and neurological disorders. A large and growing body of literature has used functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) to study the neural correlates of the antisaccade and prosaccade tasks. We present a quantitative meta-analysis of all published voxel-wise fMRI and PET studies (18) of the antisaccade task and show that consistent activation for antisaccades and prosaccades is obtained in a fronto-subcortical-parietal network encompassing frontal and supplementary eye fields (SEFs), thalamus, striatum, and intraparietal cortex. This network is strongly linked to oculomotor control and was activated to a greater extent for antisaccade than prosaccade trials. Antisaccade but not prosaccade trials additionally activated dorsolateral and ventrolateral prefrontal cortices. We also found that a number of additional regions not classically linked to oculomotor control were activated to a greater extent for antisaccade vs. prosaccade trials; these regions are often reported in antisaccade studies but rarely commented upon. While the number of studies eligible to be included in this meta-analysis was small, the results of this systematic review reveal that antisaccade and prosaccade trials consistently activate a distributed network of regions both within and outside the classic definition of the oculomotor network.
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Affiliation(s)
- Sharna D Jamadar
- Monash Biomedical Imaging, Monash University Melbourne, VIC, Australia ; School of Psychology and Psychiatry, Monash University Melbourne, VIC, Australia
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17
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Filippopulos F, Eggert T, Straube A. Deficits of cortical oculomotor mechanisms in cerebellar atrophy patients. Exp Brain Res 2012; 224:541-50. [PMID: 23161158 DOI: 10.1007/s00221-012-3332-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Accepted: 10/30/2012] [Indexed: 11/30/2022]
Abstract
Commonly, the cerebellum is not associated with cortical components of saccadic eye movement programming. The present study investigates cerebellar effects on visually guided saccades in reflexive tasks (step, gap, overlap) and on internally driven saccades in intentional tasks (anti, memory, short memory sequences of four targets) in five patients with isolated cerebellar atrophy. The cerebellar dysfunction led to impairments in both reflexive and intentional saccades. Cerebellar atrophy patients showed an increase in the gain variability and an increase in the saccade latency. Furthermore, in the memory and anti task, suppression and pro-saccade errors were more frequent in the atrophy group compared to the control group. In the sequence task, patients had difficulties reproducing all four target locations in the order of the displayed sequence. The high variability of the saccade gain is a common observation in cerebellar atrophy patients and can be explained by the general variability present in the saccadic system. The increase in the saccade latency could be due to a cerebellar contribution to cortical processes related to fixation and target selection preceding the initiation of a saccade. Furthermore, the frequent occurrence of saccade errors in the memory and anti task suggests a cerebellar involvement in frontal inhibition of unwanted reflexive saccades. The impaired reproduction of saccade sequences in atrophy patients points to a deficit in short-term memory processes. Thus, this study provides further evidence that the cerebellum is involved in different cortical mechanisms related to the control of saccadic eye movements.
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Affiliation(s)
- F Filippopulos
- Department of Neurology, Klinikum Grosshadern, Ludwig-Maximilians-Universität, Marchioninistrasse 23, 81377, Munich, Germany.
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18
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Johnson BP, Rinehart NJ, Papadopoulos N, Tonge B, Millist L, White O, Fielding J. A closer look at visually guided saccades in autism and Asperger's disorder. Front Integr Neurosci 2012; 6:99. [PMID: 23162442 PMCID: PMC3491344 DOI: 10.3389/fnint.2012.00099] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 10/13/2012] [Indexed: 11/30/2022] Open
Abstract
Motor impairments have been found to be a significant clinical feature associated with autism and Asperger’s disorder (AD) in addition to core symptoms of communication and social cognition deficits. Motor deficits in high-functioning autism (HFA) and AD may differentiate these disorders, particularly with respect to the role of the cerebellum in motor functioning. Current neuroimaging and behavioral evidence suggests greater disruption of the cerebellum in HFA than AD. Investigations of ocular motor functioning have previously been used in clinical populations to assess the integrity of the cerebellar networks, through examination of saccade accuracy and the integrity of saccade dynamics. Previous investigations of visually guided saccades in HFA and AD have only assessed basic saccade metrics, such as latency, amplitude, and gain, as well as peak velocity. We used a simple visually guided saccade paradigm to further characterize the profile of visually guided saccade metrics and dynamics in HFA and AD. It was found that children with HFA, but not AD, were more inaccurate across both small (5°) and large (10°) target amplitudes, and final eye position was hypometric at 10°. These findings suggest greater functional disturbance of the cerebellum in HFA than AD, and suggest fundamental difficulties with visual error monitoring in HFA.
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Affiliation(s)
- Beth P Johnson
- Centre for Developmental Psychiatry and Psychology, School of Psychology and Psychiatry, Monash University Melbourne, VIC, Australia
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19
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Filippopulos F, Eggert T, Straube A. Effects of cerebellar infarcts on cortical processing of saccades. J Neurol 2012; 260:805-14. [PMID: 23086179 DOI: 10.1007/s00415-012-6708-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 09/26/2012] [Accepted: 10/08/2012] [Indexed: 12/18/2022]
Abstract
The objective of the present study was to investigate cerebellar influences on cortical components of saccadic eye movement programming in human subjects. In 24 patients with a localized cerebellar lesion, saccadic eye movements were recorded in different reflexive (step, gap, overlap) and intentional (anti, memory, short memory sequences) tasks and compared to 23 healthy controls. The cerebellar lesions led to impairments in different saccade parameters. Cerebellar patients tended to show hypermetria and increased latencies compared to the control group. In particular, they executed significantly more erroneous saccades specifically in the memory task (suppression errors) but not in the anti task (pro-saccade errors). Moreover, while reproducing short sequences of saccades from memory, patients with cerebellar infarcts made more errors with regard to the sequence order than controls. The influence of cerebellar hemispheric lesions on the saccade latency, the task-specific lesion effects on the frequency of suppression errors, and the effects on the number of order errors suggest that the cerebellum is involved in cortical processes such as target selection and sequence reproduction.
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Affiliation(s)
- Filipp Filippopulos
- Department of Neurology, Ludwig-Maximilians-Universität, Klinikum Grosshadern, Marchioninistrasse 23, 81377, Munich, Germany.
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20
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Abstract
Friedreich ataxia, the most common hereditary ataxia, affects approximately 1 per 29,000 white individuals. In about 98% of these individuals, it is due to homozygosity for a GAA trinucleotide repeat expansion in intron 1 of FXN; in the other 2%, it is due to compound heterozygosity for a GAA expansion and point mutation or deletion. The condition affects multiple sites in the central and peripheral nervous system as well as a number of other organ systems, resulting in multiple signs and symptoms. Onset of this autosomal recessive condition is usually in the first 2 decades of life. Major clinical features include progressive ataxia, absent lower limb reflexes, upgoing plantar responses, and peripheral sensory neuropathy. The main nonneurological sites of morbidity are the heart, resulting in cardiomyopathy, and the pancreas, resulting in diabetes mellitus. In this review, we provide an overview of the clinical features of Friedreich ataxia and discuss differential diagnoses.
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Affiliation(s)
- Martin B Delatycki
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, VIC, Australia.
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21
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Utilisation of advance motor information is impaired in Friedreich ataxia. THE CEREBELLUM 2012; 10:793-803. [PMID: 21633800 DOI: 10.1007/s12311-011-0289-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Friedreich ataxia (FRDA) is the most common of the genetically inherited ataxias. We sought to examine motor planning ability in 13 individuals with FRDA and 13 age- and sex-matched control participants using two experimental paradigms that examined the ability to incorporate different levels of advance information to plan sequential movements. Individuals with FRDA demonstrated a differential pattern of motor response to advance information and were significantly disadvantaged by conditions requiring initiation of movement without a direct visual cue. There was also a significant negative correlation with age of disease onset and differing levels of advance information, suggesting an impact of FRDA on the development of motor cognition, independent of the effect of disease duration. We suggest that deficits are due to cerebellar impairment disrupting cerebro-ponto-cerebello-thalamo-cerebral loops (and thus cortical function), direct primary cortical pathology or a possible combination of the two.
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22
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Corben LA, Georgiou-Karistianis N, Bradshaw JL, Evans-Galea MV, Churchyard AJ, Delatycki MB. Characterising the neuropathology and neurobehavioural phenotype in Friedreich ataxia: a systematic review. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 769:169-84. [PMID: 23560311 DOI: 10.1007/978-1-4614-5434-2_11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Friedreich ataxia (FRDA), the most common of the hereditary ataxias, is an autosomal recessive, multisystem disorder characterised by progressive ataxia, sensory symptoms, weakness, scoliosis and cardiomyopathy. FRDA is caused by a GAA expansion in intron one of the FXN gene, leading to reduced levels of the encoded protein frataxin, which is thought to regulate cellular iron homeostasis. The cerebellar and spinocerebellar dysfunction seen in FRDA has known effects on motor function; however until recently slowed information processing has been the main feature consistently reported by the limited studies addressing cognitive function in FRDA. This chapter will systematically review the current literature regarding the neuropathological and neurobehavioural phenotype associated with FRDA. It will evaluate more recent evidence adopting systematic experimental methodologies that postulate that the neurobehavioural phenotype associated with FRDA is likely to involve impairment in cerebello-cortico connectivity.
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Affiliation(s)
- Louise A Corben
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, The Royal Children's Hospital, Parkville, Victoria, Australia.
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23
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Evans-Galea MV, Corben LA, Hasell J, Galea CA, Fahey MC, du Sart D, Delatycki MB. A novel deletion-insertion mutation identified in exon 3 of FXN in two siblings with a severe Friedreich ataxia phenotype. Neurogenetics 2011; 12:307-13. [PMID: 21830088 DOI: 10.1007/s10048-011-0296-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 07/22/2011] [Indexed: 10/17/2022]
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disease most commonly caused by a GAA trinucleotide repeat expansion in the first intron of FXN, which reduces expression of the mitochondrial protein frataxin. Approximately 98% of individuals with FRDA are homozygous for GAA expansions, with the remaining 2% compound heterozygotes for a GAA expansion and a point mutation within FXN. Two siblings with early onset of symptoms experienced rapid loss of ambulation by 8 and 10 years. Diagnostic testing for FRDA demonstrated one GAA repeat expansion of 1010 repeats and one non-expanded allele. Sequencing all five exons of FXN identified a novel deletion-insertion mutation in exon 3 (c.371_376del6ins15), which results in a modified frataxin protein sequence at amino acid positions 124-127. Specifically, the amino acid sequence changes from DVSF to VHLEDT, increasing frataxin from 211 residues to 214. Using the known structure of human frataxin, a theoretical 3D model of the mutant protein was developed. In the event that the modified protein is expressed and stable, it is predicted that the acidic interface of frataxin, known to be involved in iron binding and interactions with the iron-sulphur cluster assembly factor IscU, would be impaired.
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Affiliation(s)
- Marguerite V Evans-Galea
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Flemington Road, Parkville, Victoria 3052, Australia
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24
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Corben LA, Georgiou-Karistianis N, Bradshaw JL, Hocking DR, Churchyard AJ, Delatycki MB. The Fitts task reveals impairments in planning and online control of movement in Friedreich ataxia: reduced cerebellar-cortico connectivity? Neuroscience 2011; 192:382-90. [PMID: 21749914 DOI: 10.1016/j.neuroscience.2011.06.057] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 06/16/2011] [Accepted: 06/17/2011] [Indexed: 10/18/2022]
Abstract
Friedreich ataxia (FRDA) is the most common of the inherited ataxias. We have suggested that people with FRDA may have impairment in cognitive and/or psychomotor capacity either due to disturbance of projections of the cerebellum to the cortex, direct cortical pathology or perhaps both. To further explore this possibility, we used a movement task incorporating Fitts' Law, a robust description of the relationship between movement time and accuracy in goal-directed aiming movements. By manipulating task difficulty, according to target size and distance, we were able to quantify processes related to motor planning in 10 individuals with FRDA and 10 matched control participants. Compared to control participants, people with FRDA were significantly disadvantaged in terms of movement time to targets with an increasing index of difficulty. Successful completion of this task requires both preplanning of movement and online error detection and correction. The cerebellum and its connections to the frontal cortex via cerebro-ponto-cerebello-thalamo-cerebral loops are fundamental to both processes. These results lend further support to our contention that in FRDA these loops are impaired, reflecting a failure to access prefrontal/anterior regions necessary for effective management of preplanning of movement and online error correction.
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Affiliation(s)
- L A Corben
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, VIC, Australia
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25
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Greater disruption to control of voluntary saccades in autistic disorder than Asperger's disorder: evidence for greater cerebellar involvement in autism? THE CEREBELLUM 2011; 10:70-80. [PMID: 21072692 DOI: 10.1007/s12311-010-0229-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
It remains unclear whether autism and Asperger's disorder (AD) exist on a symptom continuum or are separate disorders with discrete neurobiological underpinnings. In addition to impairments in communication and social cognition, motor deficits constitute a significant clinical feature in both disorders. It has been suggested that motor deficits and in particular the integrity of cerebellar modulation of movement may differentiate these disorders. We used a simple volitional saccade task to comprehensively profile the integrity of voluntary ocular motor behaviour in individuals with high functioning autism (HFA) or AD, and included measures sensitive to cerebellar dysfunction. We tested three groups of age-matched young males with normal intelligence (full scale, verbal, and performance IQ estimates >70) aged between 11 and 19 years; nine with AD, eight with HFA, and ten normally developing males as the comparison group. Overall, the metrics and dynamics of the voluntary saccades produced in this task were preserved in the AD group. In contrast, the HFA group demonstrated relatively preserved mean measures of ocular motricity with cerebellar-like deficits demonstrated in increased variability on measures of response time, final eye position, and movement dynamics. These deficits were considered to be consistent with reduced cerebellar online adaptation of movement. The results support the notion that the integrity of cerebellar modulation of movement may be different in AD and HFA, suggesting potentially differential neurobiological substrates may underpin these complex disorders.
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26
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Corben LA, Akhlaghi H, Georgiou-Karistianis N, Bradshaw JL, Egan GF, Storey E, Churchyard AJ, Delatycki MB. Impaired inhibition of prepotent motor tendencies in Friedreich ataxia demonstrated by the Simon interference task. Brain Cogn 2011; 76:140-5. [PMID: 21354685 DOI: 10.1016/j.bandc.2011.02.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2010] [Revised: 12/17/2010] [Accepted: 02/02/2011] [Indexed: 11/16/2022]
Abstract
Friedreich ataxia (FRDA) is the most common of the genetically inherited ataxias. We recently demonstrated that people with FRDA have impairment in motor planning - most likely because of pathology affecting the cerebral cortex and/or cerebello-cortical projections. We used the Simon interference task to examine how effective 13 individuals with FRDA were at inhibiting inappropriate automatic responses associated with stimulus-response incompatibility in comparison with control participants. Participants had to respond to arrow targets according to two features which were either congruent or incongruent. We found that individuals with FRDA were differentially affected in reaction time to incongruent, compared with congruent stimuli, when compared with control participants. There was a significant negative correlation between age of onset and the incongruency effect, suggesting an impact of FRDA on the developmental unfolding of motor cognition, independent of the effect of disease duration. Future neuroimaging studies will be required to establish whether this dysfunction is due to cerebellar impairment disrupting cerebro-ponto-cerebello-thalamo-cerebral loops (and thus cortical function), direct primary cortical pathology, or a possible combination of the two.
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Affiliation(s)
- L A Corben
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
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27
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Hocking DR, Fielding J, Corben LA, Cremer PD, Millist L, White OB, Delatycki MB. Ocular motor fixation deficits in Friedreich ataxia. THE CEREBELLUM 2011; 9:411-8. [PMID: 20467851 DOI: 10.1007/s12311-010-0178-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Friedreich ataxia (FRDA) is the most common genetic cause of ataxia with a prevalence of approximately 1 in 29,000. Ocular motor abnormalities are common in FRDA and include fixation instability, saccadic dysmetria, and vestibular dysfunction. It has not yet been determined whether aspects of spatial attention, which are closely coupled to eye movements, are similarly compromised in FRDA. This study examined attentional engagement and disengagement of eye movements in FRDA using a gap overlap task. Thirteen individuals with genetically confirmed FRDA and 12 age-matched unaffected controls participated in the experiment. The gap overlap paradigm was used to examine the effect of early (gap condition), simultaneous (null condition), or late (overlap condition) removal of a central fixation on saccadic latency to a peripheral target stimulus. Although the FRDA group showed a larger gap effect (i.e., difference in saccadic latencies between the overlap and gap condition), these participants demonstrated a greater difference in latencies in the overlap relative to the null condition, suggestive of deficits within the disengagement process of attentional orienting. We propose a role for the cerebellum in these deficits in the disengagement of spatial attention based on evidence of cerebellar connectivity with regions involved in exogenous shifts of attention. The significant correlations between saccadic latency and disease severity as measured by the Friedreich Ataxia Rating Scale further support the proposal that saccadic latency might be useful as a surrogate marker of disease severity and progression in future clinical trials in FRDA.
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Affiliation(s)
- Darren R Hocking
- Bruce Lefroy Center for Genetic Health Research, Murdoch Children's Research Institute, Parkville, Victoria, Australia.
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