Sample records for cerebellar tonsillar descent

  1. Management of Cerebellar Tonsillar Herniation following Lumbar Puncture in Idiopathic Intracranial Hypertension

    PubMed Central

    Hoffman, Kenneth R.; Chan, Sean W.; Hughes, Andrew R.; Halcrow, Stephen J.

    2015-01-01

    Lumbar puncture is performed routinely for diagnostic and therapeutic purposes in idiopathic intracranial hypertension, despite lumbar puncture being classically contraindicated in the setting of raised intracranial pressure. We report the case of a 30-year-old female with known idiopathic intracranial hypertension who had cerebellar tonsillar herniation following therapeutic lumbar puncture. Management followed guidelines regarding treatment of traumatic intracranial hypertension, including rescue decompressive craniectomy. We hypothesize that the changes in brain compliance that are thought to occur in the setting of idiopathic intracranial hypertension are protective against further neuronal injury due to axonal stretch following decompressive craniectomy. PMID:25685562

  2. Hypertrophy, Tonsillar (Enlarged Tonsils) (For Parents)

    MedlinePLUS

    ... Expect Ebola: What to Know A to Z: Hypertrophy, Tonsillar (Enlarged Tonsils) KidsHealth > Parents > A to Z > ... to Know Keep in Mind A to Z: Hypertrophy, Tonsillar (Enlarged Tonsils) May also be called: Enlarged ...

  3. Tonsillar Tuberculosis: A Forgotten Clinical Entity

    PubMed Central

    Das, Anirban; Das, Sibes K.; Pandit, Sudipta; Basuthakur, Sumitra

    2015-01-01

    Tuberculosis of tonsils is an extremely rare variety of extra-pulmonary tuberculosis which frequently simulates the tonsillar malignancy, especially in elderly individuals. Secondary form is more common than primary one, and in present day, contact with the infected sputum or saliva in a case of sputum smear positive pulmonary tuberculosis is the main source of the disease. Chronic or recurrent tonsillitis with enlarged tonsils and sore throat is the main clinical presentation. As it is very difficult to differentiate it from tonsillar malignancy on clinical ground, histopathological examination of the tissue is must for the diagnosis of tonsillar TB. Antitubercular therapy is adequate for its successful resolution. Here, we report a primary form of tonsillar tuberculosis in a 76-year-old male, in whom, no pulmonary tuberculosis was documented.

  4. Cerebellar mutism

    Microsoft Academic Search

    A. Ozimek; S. Richter; B. Schoch; B. Gorißen; O. Kaiser; E. Gizewski; W. Ziegler; D. Timmann

    2004-01-01

    The aim of the present study was to investigate the manifestations of mutism after surgery in children with cerebellar tumors. Speech impairment following cerebellar mutism in children was investigated based on standardized acoustic speech parameters and perceptual criteria. Mutistic and non–mutistic children after cerebellar surgery as well as orthopedic controls were tested pre–and postoperatively. Speech impairment was compared with the

  5. [Tonsillar actinomycosis manifested as expectorated debris].

    PubMed

    Soler Sendra, Anna; Subirana Pozo, Francesc Xavier; Consola Maroto, Beatriz; Serra Carreras, Jordi; Cuquet Pedragosa, Jordi

    2009-01-01

    Actinomycosis is a festering bacterial infection frequently affecting the cervicofacial area, for which the germs responsible are Gram-positive bacilli of Actinomyces sp. We present a case of atypical presentation of actinomycosis, in the shape of repetitive mass in the tonsillar fossa with complex therapeutic management. PMID:19814991

  6. Cerebellar Arteriovenous Malformations: Anatomical Subtypes, Surgical Results, and Increased Predictive Accuracy of the Supplementary Grading System

    PubMed Central

    Rodríguez-Hernández, Ana; Kim, Helen; Pourmohamad, Tony; Young, William L.; Lawton, Michael T.

    2013-01-01

    Background Anatomical diversity amongst cerebellar AVMs calls for a classification that is intuitive and surgically informative. Selection tools like the Spetzler-Martin grading system are designed to work best with cerebral AVMs, but have shortcomings with cerebellar AVMs. Objective To define subtypes of cerebellar AVMs that clarify anatomy and surgical management, determine results according to subtypes, and compare predictive accuracies of Spetzler-Martin and supplementary systems. Methods From a consecutive surgical series of 500 patients, 60 had cerebellar AVMs, 39 had brain stem AVMs and were excluded, and 401 had cerebral AVMs. Results Cerebellar AVM subtypes were: 18 vermian, 13 suboccipital, 12 tentorial, 12 petrosal, and 5 tonsillar. Patients with tonsillar and tentorial AVMs fared best. Cerebellar AVMs presented with hemorrhage more than cerebral AVMs (p<0.001). Cerebellar AVMs were more likely to drain deep (p=0.036) and less likely eloquent (p<0.001). The predictive accuracy of supplementary grade was better than that of Spetzler-Martin grade with cerebellar AVMs (areas under the ROC curve 0.74 and 0.59, respectively). The predictive accuracy of the supplementary system was consistent for cerebral and cerebellar AVMs, whereas that of the Spetzler-Martin system was greater with cerebral AVMs. Conclusion Patients with cerebellar AVMs present with hemorrhage more than patients with cerebral AVMs, justifying an aggressive treatment posture. The supplementary system is better than the Spetzler-Martin system at predicting outcomes after cerebellar AVM resection. Key components of the Spetzler-Martin system, like venous drainage and eloquence, are distorted by cerebellar anatomy in ways that components of the supplementary system are not. PMID:22986595

  7. Cerebellar Degeneration

    MedlinePLUS

    ... Degeneration? Cerebellar degeneration is a process in which neurons in the cerebellum - the area of the brain ... proteins that are necessary for the survival of neurons. Associated diseases: Diseases that are specific to the ...

  8. Lingual tonsillar metastasis from rectal carcinoma: a rare occurrence.

    PubMed

    Su, Minggang; Jiang, Chong; Li, Lin; Li, Fanglan; Tian, Rong

    2014-06-01

    A 66-year-old man presenting with sacral pain 18 months after radical transabdominal resection of rectal mucinous adenocarcinoma underwent F-FDG PET/CT cancer surveillance. Detection of multiple nodules in lingual tonsil and left neck by imaging initially suggested tonsillar squamous carcinoma (as a second primary) with spread to cervical nodes, given the rarity with which rectal carcinoma metastasizes to the head and neck. Ultimately, the tonsillar neoplasm proved to be adenocarcinoma of colorectal origin based on its shared histologic features and compatible immunostaining profile. PMID:24686212

  9. Post-tonsillectomy pulmonary complication in a patient with tonsillar myeloid sarcoma

    Microsoft Academic Search

    Chia-Chi Cheng; Shir-Hwa Ueng; Hseuh-Yu Li; Huan-Wu Chen; Tsung-Ming Chen; Li-Ang Lee; Chung-Jan Kang; Ying-Ling Kuo; Hao-Chun Huang; Han-Ren Hsiao; Tuan-Jen Fang

    2011-01-01

    Myeloid sarcoma in a patient with myelodysplastic syndrome (MDS) manifesting as a non-healing tonsillar ulcer is an extremely\\u000a rare occurrence. We report the case of a 57-year-old male smoker with a non-healing tonsillar ulcer who underwent tonsillectomy\\u000a to rule out tonsillar carcinoma after failed antibiotic therapy. On postoperative day 2, he presented with a temperature of\\u000a 40°C and white blood

  10. Ascent/Descent Software

    NASA Technical Reports Server (NTRS)

    Brown, Charles; Andrew, Robert; Roe, Scott; Frye, Ronald; Harvey, Michael; Vu, Tuan; Balachandran, Krishnaiyer; Bly, Ben

    2012-01-01

    The Ascent/Descent Software Suite has been used to support a variety of NASA Shuttle Program mission planning and analysis activities, such as range safety, on the Integrated Planning System (IPS) platform. The Ascent/Descent Software Suite, containing Ascent Flight Design (ASC)/Descent Flight Design (DESC) Configuration items (Cis), lifecycle documents, and data files used for shuttle ascent and entry modeling analysis and mission design, resides on IPS/Linux workstations. A list of tools in Navigation (NAV)/Prop Software Suite represents tool versions established during or after the IPS Equipment Rehost-3 project.

  11. Spinal Intradural Cerebellar Ectopia

    Microsoft Academic Search

    Charles J. Chung; Mauricio Castillo; Lynn Fordham; Suresh Mukherji; William Boydston; Roger Hudgins

    Summary: An ectopic cerebellum, as in Chiari malforma- tions and ectopic cerebellar dysplastic tissue, is a common finding; however, the presence of an organized ectopic cer- ebellum is exceedingly rare. We describe the MR imaging, surgical, and histologic appearance of an intraspinal ec- topic cerebellum in an infant. Intradural spinal cerebellar ectopias are commonly seen in the Chiari malformations (1).

  12. Regulation of testicular descent.

    PubMed

    Hutson, John M; Li, Ruili; Southwell, Bridget R; Newgreen, Don; Cousinery, Mary

    2015-04-01

    Testicular descent occurs in two morphologically distinct phases, each under different hormonal control from the testis itself. The first phase occurs between 8 and 15 weeks when insulin-like hormone 3 (Insl3) from the Leydig cells stimulates the gubernaculum to swell, thereby anchoring the testis near the future inguinal canal as the foetus grows. Testosterone causes regression of the cranial suspensory ligament to augment the transabdominal phase. The second, or inguinoscrotal phase, occurs between 25 and 35 weeks, when the gubernaculum bulges out of the external ring and migrates to the scrotum, all under control of testosterone. However, androgen acts mostly indirectly via the genitofemoral nerve (GFN), which produces calcitonin gene-related peptide (CGRP) to control the direction of migration. In animal models the androgen receptors are in the inguinoscrotal fat pad, which probably produces a neurotrophin to masculinise the GFN sensory fibres that regulate gubernacular migration. There is little direct evidence that this same process occurs in humans, but CGRP can regulate closure of the processus vaginalis in inguinal hernia, confirming that the GFN probably mediates human testicular descent by a similar mechanism as seen in rodent models. Despite increased understanding about normal testicular descent, the common causes of cryptorchidism remain elusive. PMID:25690562

  13. Complementary curves of descent

    NASA Astrophysics Data System (ADS)

    Mungan, Carl E.; Lipscombe, Trevor C.

    2013-01-01

    The shapes of two wires in a vertical plane with the same starting and ending points are described as complementary curves of descent if beads frictionlessly slide down both of them in the same time, starting from rest. Every analytic curve has a unique complement, except for a cycloid (solution of the brachistochrone problem), which is self complementary. A striking example is a straight wire whose complement is a lemniscate of Bernoulli. Alternatively, the wires can be tracks down which round objects undergo a rolling race. The level of presentation is appropriate for an intermediate undergraduate course in classical mechanics.

  14. Spinal intradural cerebellar ectopia.

    PubMed

    Chung, C J; Castillo, M; Fordham, L; Mukherji, S; Boydston, W; Hudgins, R

    1998-05-01

    An ectopic cerebellum, as in Chiari malformations and ectopic cerebellar dysplastic tissue, is a common finding; however, the presence of an organized ectopic cerebellum is exceedingly rare. We describe the MR imaging, surgical, and histologic appearance of an intraspinal ectopic cerebellum in an infant. PMID:9613507

  15. Preclinical diagnosis of chronic wasting disease in captive mule deer (Odocoileus hemionus) and white-tailed deer (Odocoileus virginianus) using tonsillar biopsy

    Microsoft Academic Search

    Margaret A. Wild; Terry R. Spraker; Christina J. Sigurdson; Katherine I. O'Rourke; Michael W. Miller

    The usefulness of tonsillar biopsy on live deer for preclinical diagnosis of the transmissible spongiform encephalopathy chronic wasting disease (CWD) was evaluated. Disease was tracked in a CWD-endemic herd using serial tonsillar biopsies collected at 6 to 9 month intervals from 34 captive mule deer (Odocoileus hemionus) and five white-tailed deer (O. virginianus). Tonsillar biopsies were examined for accumulation of

  16. Cerebellar evolution in Darwin's Finches

    E-print Network

    St. Jules, Robert Sherman

    1977-01-01

    CEREBELLAR EVOLUTION IN DARWIN' S FINCHES A Thesis by ROBERT SHERMAN ST. JULES Submitted to the Graduate College of Texas MM University in partial fulfillment of roe reouiremert for the degree of MASTER OF SCIENCE May 1977 Major Subject...: Zoology CEREBELLAR EVOLUTION IN DARWIN'S FINCHES A Thesis by ROBERT SHERMAN ST. JULES Approved as to style and content by: Chairman of Committee Head of p'artment Member May 1977 ABSTRACT Cerebellar Evolution in Darwin's Finches. (Hay 1977...

  17. Metronidazole induced cerebellar ataxia

    PubMed Central

    Hari, Aditya; Srikanth, B. Akshaya; Lakshmi, G. Sriranga

    2013-01-01

    Metronidazole is a widely used antimicrobial usually prescribed by many specialist doctors for a short duration of 10-15 days. Prolonged use of metronidazole is rare. The present case is of a patient who used the drug for 4 months and developed peripheral neuropathy, convulsions, and cerebellar ataxia. He was treated with diazepam and levetiracetam. The patient recovered completely following discontinuation of metronidazole. PMID:23833378

  18. Cerebellar Glioblastoma Multiforme Presenting as Hypertensive Cerebellar Hemorrhage: Case Report

    PubMed Central

    Laki?evi?, Goran; Arnautovi?, Kenan; Muževi?, Dario; Chesney, Thomas

    2014-01-01

    Background Cerebellar glioblastoma multiforme (GBM) is rare and presents with increased intracranial pressure and cerebellar signs. The recommended treatment is radical resection, if possible, with radiation and chemotherapy. Clinical Presentation A 53-year-old man presented with hypertensive cerebellar bleeding and a 2-day history of severe headaches, nausea, vomiting, gait instability, and elevated blood pressure. Computed tomography (CT) showed a left cerebellar hematoma with no obstruction of cerebrospinal fluid and no hydrocephalus. CT angiography showed no signs of pathologic blood vessels in the posterior cranial fossa. The patient was observed in the hospital and discharged. Subsequent CT showed complete hematoma resorption. Two weeks later, he developed headaches, nausea, and worsening cerebellar symptoms. Magnetic resonance imaging (MRI) showed a 4-cm diameter tumor in the left cerebellar hemisphere where the hemorrhage was located. The tumor was radically resected and diagnosed as GBM. The patient underwent radiation and chemotherapy. At a follow-up of 1.5 years, MRIs showed no tumor recurrence. Conclusion Hypertensive cerebellar hemorrhage may be the first presentation of underlying tumor, specifically GBM. Patients undergoing surgery for cerebellar hemorrhage should have clot specimens sent for histologic examination and have pre- and postcontrast MRIs. Patients not undergoing surgery should have MRIs done after hematoma resolution to rule out underlying tumor. PMID:25097829

  19. Entry, Descent, Landing Animation (Animation)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for Entry, Descent, Landing animation

    This animation illustrates the path the Stardust return capsule will follow once it enters Earth's atmosphere.

  20. Terminal Descent Sensor Simulation

    NASA Technical Reports Server (NTRS)

    Chen, Curtis W.

    2009-01-01

    Sulcata software simulates the operation of the Mars Science Laboratory (MSL) radar terminal descent sensor (TDS). The program models TDS radar antennas, RF hardware, and digital processing, as well as the physics of scattering from a coherent ground surface. This application is specific to this sensor and is flexible enough to handle end-to-end design validation. Sulcata is a high-fidelity simulation and is used for performance evaluation, anomaly resolution, and design validation. Within the trajectory frame, almost all internal vectors are represented in whatever coordinate system is used to represent platform position. The trajectory frame must be planet-fixed. The platform body frame is specified relative to arbitrary reference points relative to the platform (spacecraft or test vehicle). Its rotation is a function of time from the trajectory coordinate system specified via dynamics input (file for open loop, callback for closed loop). Orientation of the frame relative to the body is arbitrary, but constant over time. The TDS frame must have a constant rotation and translation from the platform body frame specified at run time. The DEM frame has an arbitrary, but time-constant, rotation and translation with respect to the simulation frame specified at run time. It has the same orientation as sigma0 frame, but is possibly translated. Surface sigma0 has the same arbitrary rotation and translation as DEM frame.

  1. Modifications of moxifloxacin concentrations in plasma and tonsillar tissue after multiple administration in adults

    Microsoft Academic Search

    D. Passŕli; L. Bellussi; V. Damiani; S. Esposito; T. Mazzei; F. M. Passŕli; G. C. Passŕli

    2003-01-01

    Purpose: To evaluate modifications of moxifloxacin (MFX) concentrations in tonsillar tissue and plasma up to 24 h after three oral doses of 400 mg, and to assess the safety and tolerability of this drug in adult patients with chronic or recurrent tonsillitis undergoing tonsillectomy. Methods: Twenty-nine patients with normal renal and hepatic function were randomly placed into five groups according

  2. Syphilitic tonsillitis presenting as an ulcerated tonsillar tumor with ipsilateral lymphadenopathy.

    PubMed

    Oddó, David; Carrasco, Gonzalo; Capdeville, Felipe; Ayala, María Fernanda

    2007-10-01

    We describe a 49-year-old man who presented with a cervical mass of a week's evolution, which clinically mimicked a tumoral expansion. Physical examination showed a left cervical mass of 6 x 4 x 2 cm, associated to a left ulcerated tonsillar tumor. The presumptive diagnosis was a tonsillar cancer with lymph node involvement. An amygdalectomy and a frozen section biopsy of the cervical tumor were performed. The biopsy displayed a reactive lymphadenopathy with follicular and interfollicular hyperplasia rich in plasma cells, epithelioid areas, and an outstanding parcel fibrosis of subcapsular, interfollicular, and perifollicular distribution associated to an isolated focus of polymorphonuclear leukocytes and obliterative parietal angiovascular proliferation. The tonsil presented a similar but ulcerated process. These results suggested an infectious reactive process, probably luetic. A Warthin-Starry stain revealed spirochetes in the tonsillar ulcer. Laboratory examinations revealed a positive VDRL test and negative serology for HIV. In conclusion, a primary syphilis of the oropharyngeal tonsil with a syphilic lymphadenopathy was diagnosed. The literature about tonsillar syphilis is reviewed. PMID:17870023

  3. CD44 and Hyaluronan-dependent Rolling Interactions of Lymphocytes on Tonsillar Stroma

    E-print Network

    Springer, Timothy A.

    interactions were independent of diva-. lent cations and were mediated by CD44 binding t.:~ hyaluronanAb or hyaluronan. We propose that lymphocytes migrati~g through secondary lymphoid organs may use CD,!4 to bindCD44 and Hyaluronan-dependent Rolling Interactions of Lymphocytes on Tonsillar Stroma Rachael A

  4. [The nosology of cerebellar ataxias].

    PubMed

    Walther, J U

    1982-08-01

    The group of cerebellar ataxias in adults represents a collection of very heterogeneous causes, pathogeneses, morphological changes and - as far as the hereditary types are concerned - heredity. Different modes of inheritance (dominant or recessive) signify different aetiologies to the geneticist. However, genetic heterogeneity is often associated with similarities of the phenotypes concerned. A decisive descriptive differentiation is that between a) degenerative changes of the cerebellum and the pertaining paths and b) cerebellar ataxias with associated non-neural changes. Meanwhile consensus has been reached regarding the gross anatomical classification of cerebellar ataxias into a) olivopontocerebellar atrophies ("cerebellopetal") b) primary cerebellar parenchymatrophies ("cerebellofugal"). A more reliable classification of the monogenic types will become possible in the near future with the help of the genetic marker of the HLA haplotypes. A comprehensive classification of non-hereditary and hereditary cerebellar ataxias based on clinical, pathologico-anatomical and genetic parameters is presented and summarized in Table 4. PMID:7129327

  5. Treatable causes of cerebellar ataxia.

    PubMed

    Ramirez-Zamora, Adolfo; Zeigler, Warren; Desai, Neeja; Biller, José

    2015-04-15

    The cerebellar ataxia syndromes are a heterogeneous group of disorders clinically characterized by the presence of cerebellar dysfunction. Initial assessment of patients with progressive cerebellar ataxia is complex because of an extensive list of potential diagnoses. A detailed history and comprehensive examination are required for an accurate diagnosis and hierarchical diagnostic investigations. Although no cure exists for most of these conditions, a small group of metabolic, hereditary, inflammatory, and immune-mediated etiologies of cerebellar ataxia are amenable to disease-modifying, targeted therapies. Over the past years, disease-specific treatments have emerged. Thus, clinicians must become familiar with these disorders because maximal therapeutic benefit is only possible when done early. In this article, we review disorders in which cerebellar ataxia is a prominent clinical feature requiring targeted treatments along with specific management recommendations. © 2015 International Parkinson and Movement Disorder Society. PMID:25757427

  6. Descent and descent groups in lovedu social structure

    Microsoft Academic Search

    Eileen Jensen Krige

    1985-01-01

    The basic unit in Lovedu society is the extended family, the minimal descent group, of three, and occasionally four generations living together in a village under the control of the patriarch, or, after his death, of his son, the eldest in the chief house. It is a corporate group of considerable importance.An initial examination in this paper of situations in

  7. Cerebellar contributions to spatial memory.

    PubMed

    Tomlinson, Simon P; Davis, Nick J; Morgan, Helen M; Bracewell, R Martyn

    2014-08-22

    There is mounting evidence for a role for the cerebellum in working memory (WM). The majority of relevant studies has examined verbal WM and has suggested specialisation of the right cerebellar hemisphere for language processing. Our study used theta burst stimulation (TBS) to examine whether there is a converse cerebellar hemispheric specialisation for spatial WM. We conducted two experiments to examine spatial WM performance before and after TBS to mid-hemispheric and lateral locations in the posterior cerebellum. Participants were required to recall the order of presentation of targets on a screen or the targets' order of presentation and their locations. We observed impaired recollection of target order after TBS to the mid left cerebellar hemisphere and reduced response speed after TBS to the left lateral cerebellum. We suggest that these results give evidence of the contributions of the left cerebellar cortex to the encoding and retrieval of spatial information. PMID:25004407

  8. Cerebellar ataxia in enteric fever

    Microsoft Academic Search

    R S Wadia; N R Ichaporia; R S Kiwalkar; R B Amin; H V Sardesai

    1985-01-01

    In a study of enteric fever, cerebellar ataxia was found to be the commonest neurological manifestation, second only to toxic delirium. Excluding toxic delirium (found in 25-30% of cases) neurologic deficit was noted in 5.0% of a series of 718 consecutive cases; 2.3% showed cerebellar ataxia, either as an isolated feature or in association with other lesions. The ataxia usually

  9. Privacy-Preserving Gradient-Descent Methods

    Microsoft Academic Search

    Shuguo Han; Wee Keong Ng; Li Wan; Vincent C. S. Lee

    2010-01-01

    Gradient descent is a widely used paradigm for solving many optimization problems. Gradient descent aims to minimize a target function in order to reach a local minimum. In machine learning or data mining, this function corresponds to a decision model that is to be discovered. In this paper, we propose a preliminary formulation of gradient descent with data privacy preservation.

  10. stochastic gradient descent nonlinear transformation

    E-print Network

    Abu-Mostafa, Yaser S.

    ÁŘł× ŮŇ Đ ÓŮŘ Ř Ö stochastic gradient descent nonlinear transformation overfitting data snooping deterministic noise noisy targets bias-variance tradeoff RBF SVM weight decay regularization soft supervised online active neural networks RBF nearest neighbors SVD linear SVM aggregation input processing

  11. Descent into theDescent into theDescent into theDescent into the Hell of VenusHell of VenusHell of VenusHell of Venus

    E-print Network

    Alfonseca, Manuel

    Descent into theDescent into theDescent into theDescent into the Hell of VenusHell of VenusHell of VenusHell of Venus Manuel AlfonsecaManuel AlfonsecaManuel AlfonsecaManuel Alfonseca #12;Manuel Alfonseca 2 #12;Descent into the Hell of Venus 3 DESCENT INTO THE HELL OF VENUS Manuel Alfonseca All Rights

  12. Changes in chemokines and chemokine receptor expression on tonsillar B cells upon Epstein-Barr virus infection.

    PubMed

    Ehlin-Henriksson, Barbro; Liang, Wu; Cagigi, Alberto; Mowafi, Frida; Klein, George; Nilsson, Anna

    2009-08-01

    Chemokines and chemokine receptors are likely to play important roles in the pathogenesis of Epstein-Barr virus (EBV) -associated disease. The primary EBV infection occurs in the oropharynx where the virus infects mainly tonsillar B cells. We have previously shown that CXCR4 expression on tonsillar B cells is modulated by EBV. Here, CXCR5 and CCR7 expression, which is important for migration into lymphoid tissue, was followed for 14 days after EBV infection of tonsillar B cells. Early after infection (2 days) there were only minor changes in CXCR5 and CCR7 expression. However, at day 7 the expression of CXCR5, as well as of CCR7, was decreased and by day 14 these molecules were no longer present at the cell surface. Furthermore, EBV infection affects the chemotactic response to CXCL13 and CCL21 (the ligands for CXCR5 and CCR7, respectively) with a reduction of ligand-induced migration at day 2. Using gene expression profiling, we identified an additional set of chemokines and chemokine receptors that were changed upon EBV infection in comparison with non-infected tonsillar B cells. In particular, messenger RNA expression for CCR9 and the complement receptor C5AR1 was increased. Both receptors mediate homing to mucosal tissue. The alterations of the expression of these molecules may lead to retention of EBV-infected tonsillar B cells in the interfollicular region of the tonsil. PMID:19604305

  13. Alcohol Withdrawal and Cerebellar Mitochondria.

    PubMed

    Jung, Marianna E

    2014-09-01

    Cerebellar disorders trigger the symptoms of movement problems, imbalance, incoordination, and frequent fall. Cerebellar disorders are shown in various CNS illnesses including a drinking disorder called alcoholism. Alcoholism is manifested as an inability to control drinking in spite of adverse consequences. Human and animal studies have shown that cerebellar symptoms persist even after complete abstinence from drinking. In particular, the abrupt termination (ethanol withdrawal) of long-term excessive ethanol consumption has shown to provoke a variety of neuronal and mitochondrial damage to the cerebellum. Upon ethanol withdrawal, excitatory neurotransmitter molecules such as glutamate are overly released in brain areas including cerebellum. This is particularly relevant to the cerebellar neuronal network as glutamate signals are projected to Purkinje neurons through granular cells that are the most populated neuronal type in CNS. This excitatory neuronal signal may be elevated by ethanol withdrawal stress, which promotes an increase in intracellular Ca(2+) level and a decrease in a Ca(2+)-binding protein, both of which result in the excessive entry of Ca(2+) to the mitochondria. Subsequently, mitochondria undergo a prolonged opening of mitochondrial permeability transition pore and the overproduction of harmful free radicals, impeding adenosine triphosphate (ATP)-generating function. This in turn provokes the leakage of mitochondrial molecule cytochrome c to the cytosol, which triggers a cascade of adverse cytosol reactions. Upstream to this pathway, cerebellum under the condition of ethanol withdrawal has shown aberrant gene modifications through altered DNA methylation, histone acetylation, or microRNA expression. Interplay between these events and molecules may result in functional damage to cerebellar mitochondria and consequent neuronal degeneration, thereby contributing to motoric deficit. Mitochondria-targeting research may help develop a powerful new therapy to manage cerebellar disorders associated with hyperexcitatory CNS disorders like ethanol withdrawal. PMID:25195804

  14. Ectopic Oral Tonsillar Tissue: A Case Series with Bilateral and Solitary Presentations and a Review of the Literature

    PubMed Central

    Kimura, Masashi; Nagao, Toru; Saito, Terumi; Warnakulasuriya, Saman; Ohto, Hiroyuki; Takahashi, Akihito; Komaki, Kanji; Naganawa, Yoshiyuki

    2015-01-01

    An ectopic tonsil is defined as tonsillar tissue that develops in areas outside of the four major tonsil groups: the palatine, lingual, pharyngeal, and tubal tonsils. The occurrence of tonsillar tissue in the oral cavity in ectopic locations, its prevalence, and its developmental mechanisms that belong to its formation remain unclear. In this report, we describe a rare case of bilateral symmetric ectopic oral tonsillar tissue located at the ventral surface of the tongue along with two solitary cases arising from the floor of the mouth. The role of immune system and its aberrant response leading to ectopic deposits desires further studies. As an ectopic tonsil may simulate a benign soft tissue tumor, this case series highlights the importance of this entity in our clinical differential diagnosis of oral soft tissue masses. PMID:25664186

  15. Molecular mapping to species level of the tonsillar crypt microbiota associated with health and recurrent tonsillitis.

    PubMed

    Jensen, Anders; Fagö-Olsen, Helena; Sřrensen, Christian Hjort; Kilian, Mogens

    2013-01-01

    The human palatine tonsils, which belong to the central antigen handling sites of the mucosal immune system, are frequently affected by acute and recurrent infections. This study compared the microbiota of the tonsillar crypts in children and adults affected by recurrent tonsillitis with that of healthy adults and children with tonsillar hyperplasia. An in-depth 16S rRNA gene based pyrosequencing approach combined with a novel strategy that included phylogenetic analysis and detection of species-specific sequence signatures enabled identification of the major part of the microbiota to species level. A complex microbiota consisting of between 42 and 110 taxa was demonstrated in both children and adults. This included a core microbiome of 12 abundant genera found in all samples regardless of age and health status. Yet, Haemophilus influenzae, Neisseria species, and Streptococcus pneumoniae were almost exclusively detected in children. In contrast, Streptococcus pseudopneumoniae was present in all samples. Obligate anaerobes like Porphyromonas, Prevotella, and Fusobacterium were abundantly present in children, but the species diversity of Porphyromonas and Prevotella was larger in adults and included species that are considered putative pathogens in periodontal diseases, i.e. Porphyromonas gingivalis, Porphyromonas endodontalis, and Tannerella forsythia. Unifrac analysis showed that recurrent tonsillitis is associated with a shift in the microbiota of the tonsillar crypts. Fusobacterium necrophorum, Streptococcus intermedius and Prevotella melaninogenica/histicola were associated with recurrent tonsillitis in adults, whereas species traditionally associated with acute tonsillitis like pyogenic streptococci and Staphylococcus aureus were scarce. The findings suggest that recurrent tonsillitis is a polymicrobial infection in which interactions within consortia of taxa play an etiologic role. The study contributes to the human microbiome data, to the understanding of the etiology of infections affecting the tonsils, and forms a basis for further insight into the consequences of the intense microbe-host interactions that take place in the tonsils. PMID:23437130

  16. Algorithm for Fuel-Conservative Airplane Descents

    NASA Technical Reports Server (NTRS)

    Knox, C. E.; Vicroy, D. D.; Simmon, D. A.

    1986-01-01

    Federal Aviation Administration implementing automated, time-based metering form of air-traffic control (ATC) with profile-descent procedures for arrivals into terminal area. Measures provide fuel savings by matching arrival of airplanes to airport acceptance rate through time-control computations and allowing pilot to descend at his discretion from cruise altitude to designated metering-fix altitude in idle-thrust clean configuration. Airborne descent algorithm developed compatible with time-based metering and profile-descent procedures and designed to improve accuracy of delivering airplane during fuel-efficient descent to metering fix at time designated by the ATC system.

  17. Effects of guidelines on adeno-tonsillar surgery on the clinical behaviour of otorhinolaryngologists in Italy

    PubMed Central

    2013-01-01

    Background Several guidelines on adeno-tonsillar disease have been proposed in recent years and some discrepancies in relation both to clinical manifestations and indications for surgical treatment have emerged. The aim of the study was to verify what influence (adeno)-tonsillectomy guidelines have had on the clinical behaviour of ENT specialists in Italy. Our study is a retrospective and multi-centre case series with chart review. Methods The survey involved 14,770 children, aged between the ages of 2 and 11, who had undergone adeno-tonsillar surgery between 2002 and 2008 in fourteen Italian tertiary and secondary referral centres. Anova test was used for the statistical analysis, assuming p < 0.05 as the minimum statistical significance value. Results The frequency of adeno-tonsillar surgeries did not change significantly (p>0.05) during the study period and following the Italian policy document publication. Overall, adeno-tonsillectomy was the most frequent intervention (64.1%), followed by adenoidectomy (31.1%) and tonsillectomy (4.8%). The indications for surgery did not change significantly for each of the operations (p>0.05), with the exception of adeno-tonsillectomy in case of feverish episodes due to acute recurrent tonsillitis ? 5 without nasal obstruction (decreased p= 0.010) , even when the feverish episodes due to acute recurrent tonsillitis were < 5 over the last year. Nasal obstruction was associated with feverish episodes due to acute recurrent tonsillitis in 65.2% of operated cases, while otitis media had been diagnosed in 43.3% of the patients studied. Conclusions The recommendations first developed in Italy in a 2003 policy document and then resumed in guidelines in 2008, were not implemented by ENT units involved in the survey. The study highlights the fact that the indications for adeno-tonsillar operations are based on the overall clinical presentation (comorbidity) rather than on a single symptom. Guidelines are necessary to give coherent recommendations based on both the findings obtained through randomized controlled trials and the data collected from observational studies. PMID:23294984

  18. [The problem of the mandible in surgery of tonsillar tumors: proposal of a technique].

    PubMed

    Vercellino, V; Pomatto, E; Solazzo, L; Meloni, F; Stomeo, F; Teatini, G P

    1990-01-01

    The Authors report a technique of a conservative transmandibular approach for the surgical treatment of tonsillar region malignancies. The procedure is based upon the preparation of a vascular mandibular flap through two osteotomies, which are performed, the first above the mandibular foramen and the second below the mental foramen. The main advantages of present technique are: lip-chin-splitting is avoided and, due to the preservation of mandibular vascular and nervous supply, it is possible to accomplish, without risk, postoperative radiotherapy. Moreover, if dictated by oncologic reasons, this conservative procedure may easily be transformed into a radical surgery (commando or neck-jaw operation). PMID:2103090

  19. Speech Prosody in Cerebellar Ataxia

    ERIC Educational Resources Information Center

    Casper, Maureen A.; Raphael, Lawrence J.; Harris, Katherine S.; Geibel, Jennifer M.

    2007-01-01

    Persons with cerebellar ataxia exhibit changes in physical coordination and speech and voice production. Previously, these alterations of speech and voice production were described primarily via perceptual coordinates. In this study, the spatial-temporal properties of syllable production were examined in 12 speakers, six of whom were healthy…

  20. Familial cerebellar ataxia with hypogonadism

    Microsoft Academic Search

    A. Lowenthal; J. Bekaert; F. Van Dessel; J. van Hauwaert

    1979-01-01

    A brother and sister with congenital cerebellar ataxia, anosmia, oligophrenia, hypogonadism and anomalies of amino acid distribution are reported. Ties between the different symptoms are difficult to establish. It seems to be a new syndrome rather than a new disease. Once more these associations emphasize the need for metabolic and biochemical research in heredodegenerative diseases. The evolution of the disease

  1. Linking oscillations in cerebellar circuits

    PubMed Central

    Courtemanche, Richard; Robinson, Jennifer C.; Aponte, Daniel I.

    2013-01-01

    In many neuroscience fields, the study of local and global rhythmicity has been receiving increasing attention. These network influences could directly impact on how neuronal groups interact together, organizing for different contexts. The cerebellar cortex harbors a variety of such local circuit rhythms, from the rhythms in the cerebellar cortex per se, or those dictated from important afferents. We present here certain cerebellar oscillatory phenomena that have been recorded in rodents and primates. Those take place in a range of frequencies: from the more known oscillations in the 4–25 Hz band, such as the olivocerebellar oscillatory activity and the granule cell layer oscillations, to the more recently reported slow (<1 Hz oscillations), and the fast (>150 Hz) activity in the Purkinje cell layer. Many of these oscillations appear spontaneously in the circuits, and are modulated by behavioral imperatives. We review here how those oscillations are recorded, some of their modulatory mechanisms, and also identify some of the cerebellar nodes where they could interact. A particular emphasis has been placed on how these oscillations could be modulated by movement and certain neuropathological manifestations. Many of those oscillations could have a definite impact on the way information is processed in the cerebellum and how it interacts with other structures in a variety of contexts. PMID:23908606

  2. Consert during the Philae Descent

    NASA Astrophysics Data System (ADS)

    Herique, Alain; Berquin, Yann; Blazquez, Alejandro; Antoine Foulon, Marc; Hahnel, Ronny; Hegler, Sebastian; Jurado, Eric; Kofman, Wlodek; Plettemeier, Dirk; Rogez, Yves; Statz, Christoph; Zine, Sonia

    2014-05-01

    The CONSERT experiment on board Rosetta and Philae is to perform the tomography of the 67P/CG comet nucleus measuring radio waves transmission from the Rosetta S/C to the Philae Lander and using the 67P nucleus rotation to cover different geometries. CONSERT will operate during the Philae descent. This geometry strongly differs from the "nominal" bistatic tomography where the orbiter is on the opposite side of the nucleus by regard to the lander. During the descent, CONSERT will measure direct wave propagating from orbiter to lander and waves reflected / scattered by the 67P surface and subsurface. This signal will provide information of the greatest interest for both scientific investigations of 67P and technical operations of Philae. The landing site position is known a priori with a large ellipse of dispersion due to uncertainties on the Rosetta velocity and Rosetta/Philae separation strength. This dispersion is increased by the difference between nominal and emergency separation strength. An accurate estimation of the landing position as soon as possible after landing is of the greatest interest to optimize Philae operation during FSS. So propagation delay of the direct and reflected waves measured by CONSERT will help to reconstruct the descent geometry in order to more precisely estimate the landing position. The reflected signal is determined by the surface properties: its dielectric permittivity, its roughness and layering. The signal power inversion will allow to map surface properties especially in the vicinity of the landing site. This paper details the measurement configuration. It presents the data retrieval based on Monte-Carlo simulation using Metropolis-Hastings algorithm and expected performances for both science and operations.

  3. Descent theory for semiorthogonal decompositions

    SciTech Connect

    Elagin, Alexei D

    2012-05-31

    We put forward a method for constructing semiorthogonal decompositions of the derived category of G-equivariant sheaves on a variety X under the assumption that the derived category of sheaves on X admits a semiorthogonal decomposition with components preserved by the action of the group G on X. This method is used to obtain semiorthogonal decompositions of equivariant derived categories for projective bundles and blow-ups with a smooth centre as well as for varieties with a full exceptional collection preserved by the group action. Our main technical tool is descent theory for derived categories. Bibliography: 12 titles.

  4. KSHV infects a subset of human tonsillar B cells, driving proliferation and plasmablast differentiation.

    PubMed

    Hassman, Lynn M; Ellison, Thomas J; Kedes, Dean H

    2011-02-01

    Kaposi sarcoma-associated herpesvirus (KSHV; also known as HHV8) is the causative agent of two B cell tumors, multicentric Castleman disease (MCD) and primary effusion lymphoma (PEL). However, little is known about the nature of the specific B cell subtype(s) most susceptible to infection. Identifying these cells would provide direct insight into KSHV transmission and virus-induced transformation. To identify this subset and to determine whether infection alters its cellular phenotype, we exposed human tonsillar cells to KSHV and characterized infected cells using high-throughput multispectral imaging flow cytometry (MIFC). Stable expression of the virally encoded latency-associated nuclear antigen (LANA), a marker of latent KSHV infection, was observed predominantly in cells expressing the l light chain of the B cell receptor. These LANA+ B cells proliferated and exhibited similarities to the cells characteristic of MCD (IgMl-expressing plasmablasts), including blasting morphology with elevated expression of Ki67, variable expression of CD27, and high levels of IgM and IL-6 receptor. Furthermore, the proportion of infected cells showing a blasting phenotype increased upon addition of exogenous IL-6. Our data lead us to propose that oral transmission of KSHV involves the latent infection of a subset of tonsillar IgMl-expressing B cells, which then proliferate as they acquire the plasmablast phenotype characteristic of MCD. PMID:21245574

  5. Stochastic Gradient Descent with Only One Projection

    E-print Network

    , such as celebrated Stochastic Gradient Descent (SGD) [16, 2] and its online counterpart Online Gradient Descent (OGD, the lightweight computation per iteration makes SGD attractive for many large-scale learning problems. To find a solution within the domain K that optimizes the given objective function f(x), SGD computes an unbiased

  6. Stochastic Gradient Descent Tricks Leon Bottou

    E-print Network

    Bottou, Léon

    gradient descent (SGD). This chapter provides background material, explains why SGD is a good learning an instance of a more general technique called stochastic gradient descent (SGD). This chapter provides background material, explains why SGD is a good learning algorithm when the training set is large

  7. Predictability of Top of Descent Location for Operational Idle-Thrust Descents

    NASA Technical Reports Server (NTRS)

    Stell, Laurel L.

    2010-01-01

    To enable arriving aircraft to fly optimized descents computed by the flight management system (FMS) in congested airspace, ground automation must accurately predict descent trajectories. To support development of the trajectory predictor and its uncertainty models, commercial flights executed idle-thrust descents at a specified descent speed, and the recorded data included the specified descent speed profile, aircraft weight, and the winds entered into the FMS as well as the radar data. The FMS computed the intended descent path assuming idle thrust after top of descent (TOD), and the controllers and pilots then endeavored to allow the FMS to fly the descent to the meter fix with minimal human intervention. The horizontal flight path, cruise and meter fix altitudes, and actual TOD location were extracted from the radar data. Using approximately 70 descents each in Boeing 757 and Airbus 319/320 aircraft, multiple regression estimated TOD location as a linear function of the available predictive factors. The cruise and meter fix altitudes, descent speed, and wind clearly improve goodness of fit. The aircraft weight improves fit for the Airbus descents but not for the B757. Except for a few statistical outliers, the residuals have absolute value less than 5 nmi. Thus, these predictive factors adequately explain the TOD location, which indicates the data do not include excessive noise.

  8. CEREBELLAR GRANULE CELLS IN VITRO

    PubMed Central

    Seil, Fredrick J.; Herndon, Robert M.

    1970-01-01

    The behavior of granule cells in mature cerebellar cultures derived from newborn mice was studied by light and electron microscopy. Many granule cells remained in the explants as an external granular layer. These cells were differentiated, as evidenced by formation of bundles of parallel fibers and by development of synapses between granule cell axons and Purkinje cell branchlet spines, and between Golgi cell axons and granule cell dendrites. Although the over-all architecture of the cerebellar explants after 18–33 days in vitro was similar to that of the newborn mouse, the evident differentiation of the granule cells suggested that interneuronal relationships resemble those of the mature cerebellum in vivo. PMID:5513604

  9. Cerebellar Degeneration Associated with Sjögren's Syndrome

    PubMed Central

    Kim, Mi Jung; Lee, Myoung Chong; Lee, Jae-Hong

    2012-01-01

    Background Neurologic manifestations of primary Sjögren's syndrome (PSS) have been reported to vary from sensory polyneuropathy to encephalopathy or psychiatric problems. However, marked cerebellar degeneration associated with PSS has rarely been reported. Case Report We describe a patient with Sjögren's syndrome who exhibited rapidly progressive cerebellar ataxia, nystagmus, cognitive decline, and psychiatric problems. Brain magnetic resonance imaging revealed marked atrophy of the cerebellum, and 18F-fluorodeoxyglucose positron-emission tomography demonstrated glucose hypometabolism of the cerebellum. Conclusions Our PSS patient exhibited a progressive course of cerebellar syndrome, as evidenced by cerebellar atrophy on serial brain images. PMID:22787501

  10. The cerebellum, cerebellar disorders, and cerebellar research--two centuries of discoveries.

    PubMed

    Manto, Mario

    2008-01-01

    Research on the cerebellum is evolving rapidly. The exquisiteness of the cerebellar circuitry with a unique geometric arrangement has fascinated researchers from numerous disciplines. The painstaking works of pioneers of these last two centuries, such as Rolando, Flourens, Luciani, Babinski, Holmes, Cajal, Larsell, or Eccles, still exert a strong influence in the way we approach cerebellar functions. Advances in genetic studies, detailed molecular and cellular analyses, profusion of brain imaging techniques, emergence of behavioral assessments, and reshaping of models of cerebellar function are generating an immense amount of knowledge. Simultaneously, a better definition of cerebellar disorders encountered in the clinic is emerging. The essentials of a trans-disciplinary blending are expanding. The analysis of the literature published these last two decades indicates that the gaps between domains of research are vanishing. The launch of the society for research on the cerebellum (SRC) illustrates how cerebellar research is burgeoning. This special issue gathers the contributions of the inaugural conference of the SRC dedicated to the mechanisms of cerebellar function. Contributions were brought together around five themes: (1) cerebellar development, death, and regeneration; (2) cerebellar circuitry: processing and function; (3) mechanisms of cerebellar plasticity and learning; (4) cerebellar function: timing, prediction, and/or coordination?; (5) anatomical and disease perspectives on cerebellar function. PMID:18855093

  11. Incidence of basilar invagination in patients with tonsillar herniation? A case control craniometrical study.

    PubMed

    Joaquim, Andrei F; Fernandes, Yvens Barbosa; Mathias, Roger N; Batista, Ulysses C; Ghizoni, Enrico; Tedeschi, Helder; Patel, Alpesh A

    2014-09-01

    A retrospective case-control study based on craniometrical evaluation was performed to evaluate the incidence of basilar invagination (BI). Patients with symptomatic tonsillar herniation treated surgically had craniometrical parameters evaluated based on CT scan reconstructions before surgery. BI was diagnosed when the tip of the odontoid trespassed the Chamberlain's line in three different thresholds found in the literature: 2, 5 or 6.6 mm. In the surgical group (SU), the mean distance of the tip of the odontoid process above the Chamberlain's line was 12 mm versus 1.2 mm in the control (CO) group (p<0.0001). The number of patients with BI according to the threshold used (2, 5 or 6.6 mm) in the SU group was respectively 19 (95%), 16 (80%) and 15 (75%) and in the CO group it was 15 (37%), 4 (10%) and 2 (5%). PMID:25252235

  12. Efficient parallel coordinate descent algorithm for convex ...

    E-print Network

    2012-12-21

    Keywords: Coordinate descent optimization, parallel algorithm, (sub)linear convergence .... vector on these sets and can be done numerically very efficient. For exam- ... quadratic problems are solved with an interior point solver. From (6)-

  13. Feature Clustering for Accelerating Parallel Coordinate Descent

    SciTech Connect

    Scherrer, Chad; Tewari, Ambuj; Halappanavar, Mahantesh; Haglin, David J.

    2012-12-06

    We demonstrate an approach for accelerating calculation of the regularization path for L1 sparse logistic regression problems. We show the benefit of feature clustering as a preconditioning step for parallel block-greedy coordinate descent algorithms.

  14. Lunar descent using sequential engine shutdown

    E-print Network

    Springmann, Philip N

    2006-01-01

    The notion of sequential engine shutdown is introduced and its application to lunar descent is motivated. The concept calls for the utilization of multiple fixed thrust engines in place of a single continuously throttleable ...

  15. Consensus Paper: Management of Degenerative Cerebellar Disorders

    PubMed Central

    Ilg, W.; Bastian, A. J.; Boesch, S.; Burciu, R. G.; Celnik, P.; Claaßen, J.; Feil, K.; Kalla, R.; Miyai, I.; Nachbauer, W.; Schöls, L.; Strupp, M.; Synofzik, M.; Teufel, J.

    2015-01-01

    Treatment of motor symptoms of degenerative cerebellar ataxia remains difficult. Yet there are recent developments that are likely to lead to significant improvements in the future. Most desirable would be a causative treatment of the underlying cerebellar disease. This is currently available only for a very small subset of cerebellar ataxias with known metabolic dysfunction. However, increasing knowledge of the pathophysiology of hereditary ataxia should lead to an increasing number of medically sensible drug trials. In this paper, data from recent drug trials in patients with recessive and dominant cerebellar ataxias will be summarized. There is consensus that up to date, no medication has been proven effective. Aminopyridines and acetazolamide are the only exception, which are beneficial in patients with episodic ataxia type 2. Aminopyridines are also effective in a subset of patients presenting with downbeat nystagmus. As such, all authors agreed that the mainstays of treatment of degenerative cerebellar ataxia are currently physiotherapy, occupational therapy, and speech therapy. For many years, well-controlled rehabilitation studies in patients with cerebellar ataxia were lacking. Data of recently published studies show that coordinative training improves motor function in both adult and juvenile patients with cerebellar degeneration. Given the well-known contribution of the cerebellum to motor learning, possible mechanisms underlying improvement will be outlined. There is consensus that evidence-based guidelines for the physiotherapy of degenerative cerebellar ataxia need to be developed. Future developments in physiotherapeutical interventions will be discussed including application of non-invasive brain stimulation. PMID:24222635

  16. Learning of Sensory Sequences in Cerebellar Patients

    ERIC Educational Resources Information Center

    Frings, Markus; Boenisch, Raoul; Gerwig, Marcus; Diener, Hans-Christoph; Timmann, Dagmar

    2004-01-01

    A possible role of the cerebellum in detecting and recognizing event sequences has been proposed. The present study sought to determine whether patients with cerebellar lesions are impaired in the acquisition and discrimination of sequences of sensory stimuli of different modalities. A group of 26 cerebellar patients and 26 controls matched for…

  17. Apollo experience report: Descent propulsion system

    NASA Technical Reports Server (NTRS)

    Hammock, W. R., Jr.; Currie, E. C.; Fisher, A. E.

    1973-01-01

    The propulsion system for the descent stage of the lunar module was designed to provide thrust to transfer the fully loaded lunar module with two crewmen from the lunar parking orbit to the lunar surface. A history of the development of this system is presented. Development was accomplished primarily by ground testing of individual components and by testing the integrated system. Unique features of the descent propulsion system were the deep throttling capability and the use of a lightweight cryogenic helium pressurization system.

  18. Descent relations in cubic superstring field theory

    NASA Astrophysics Data System (ADS)

    Aref'eva, I. Y.; Gorbachev, R.; Medvedev, P. B.; Rychkov, D. V.

    2008-01-01

    The descent relations between string field theory (SFT) vertices are characteristic relations of the operator formulation of SFT and they provide self-consistency of this theory. The descent relations langleV2|V1rangle and langleV3|V1rangle in the NS fermionic string field theory in the ? and discrete bases are established. Different regularizations and schemes of calculations are considered and relations between them are discussed.

  19. Descent Advisor Preliminary Field Test

    NASA Technical Reports Server (NTRS)

    Green, Steven M.; Vivona, Robert A.; Sanford, Beverly

    1995-01-01

    A field test of the Descent Advisor (DA) automation tool was conducted at the Denver Air Route Traffic Control Center in September 1994. DA is being developed to assist Center controllers in the efficient management and control of arrival traffic. DA generates advisories, based on trajectory predictions, to achieve accurate meter-fix arrival times in a fuel efficient manner while assisting the controller with the prediction and resolution of potential conflicts. The test objectives were: (1) to evaluate the accuracy of DA trajectory predictions for conventional and flight-management system equipped jet transports, (2) to identify significant sources of trajectory prediction error, and (3) to investigate procedural and training issues (both air and ground) associated with DA operations. Various commercial aircraft (97 flights total) and a Boeing 737-100 research aircraft participated in the test. Preliminary results from the primary test set of 24 commercial flights indicate a mean DA arrival time prediction error of 2.4 seconds late with a standard deviation of 13.1 seconds. This paper describes the field test and presents preliminary results for the commercial flights.

  20. Developmental Cerebellar Cognitive Affective Syndrome in Ex-preterm Survivors Following Cerebellar Injury.

    PubMed

    Brossard-Racine, Marie; du Plessis, Adre J; Limperopoulos, Catherine

    2015-04-01

    Cerebellar injury is increasingly recognized as an important complication of very preterm birth. However, the neurodevelopmental consequences of early life cerebellar injury in prematurely born infants have not been well elucidated. We performed a literature search of studies published between 1997 and 2014 describing neurodevelopmental outcomes of preterm infants following direct cerebellar injury or indirect cerebellar injury/underdevelopment. Available data suggests that both direct and indirect mechanisms of cerebellar injury appear to stunt cerebellar growth and adversely affect neurodevelopment. This review also provides important insights into the highly integrated cerebral-cerebellar structural and functional correlates. Finally, this review highlights that early life impairment of cerebellar growth extends far beyond motor impairments and plays a critical, previously underrecognized role in the long-term cognitive, behavioral, and social deficits associated with brain injury among premature infants. These data point to a developmental form of the cerebellar cognitive affective syndrome previously described in adults. Longitudinal prospective studies using serial advanced magnetic resonance imaging techniques are needed to better delineate the full extent of the role of prematurity-related cerebellar injury and topography in the genesis of cognitive, social-behavioral dysfunction. PMID:25241880

  1. Time Estimation Deficits in Developmental Dyslexia: Evidence of Cerebellar Involvement

    Microsoft Academic Search

    Roderick I. Nicolson; Angela J. Fawcett; Paul Dean

    1995-01-01

    In addition to their language-related difficulties, dyslexic children suffer problems in motor skill, balance, automatization and speeded performance. Given the recent evidence for cerebellar involvement in the acquisition of language fluency, these problems suggest cerebellar deficit. To test the hypothesis of cerebellar dysfunction in dyslexia, a time estimation task considered to be a sensitive index of cerebellar function was administered

  2. X-linked disorders with cerebellar dysgenesis

    PubMed Central

    2011-01-01

    X-linked disorders with cerebellar dysgenesis (XLCD) are a genetically heterogeneous and clinically variable group of disorders in which the hallmark is a cerebellar defect (hypoplasia, atrophy or dysplasia) visible on brain imaging, caused by gene mutations or genomic imbalances on the X-chromosome. The neurological features of XLCD include hypotonia, developmental delay, intellectual disability, ataxia and/or other cerebellar signs. Normal cognitive development has also been reported. Cerebellar dysgenesis may be isolated or associated with other brain malformations or multiorgan involvement. There are at least 15 genes on the X-chromosome that have been constantly or occasionally associated with a pathological cerebellar phenotype. 8 XLCD loci have been mapped and several families with X-linked inheritance have been reported. Recently, two recurrent duplication syndromes in Xq28 have been associated with cerebellar hypoplasia. Given the report of several forms of XLCD and the excess of males with ataxia, this group of conditions is probably underestimated and families of patients with neuroradiological and clinical evidence of a cerebellar disorder should be counseled for high risk of X-linked inheritance. PMID:21569638

  3. Cerebellar contributions to verbal working memory.

    PubMed

    Tomlinson, Simon P; Davis, Nick J; Morgan, Helen M; Bracewell, R Martyn

    2014-06-01

    There is increasing evidence for a cerebellar role in working memory. Clinical research has shown that working memory impairments after cerebellar damage and neuroimaging studies have revealed task-specific activation in the cerebellum during working memory processing. A lateralisation of cerebellar function within working memory has been proposed with the right hemisphere making the greater contribution to verbal processing and the left hemisphere for visuospatial tasks. We used continuous theta burst stimulation (cTBS) to examine whether differences in post-stimulation performance could be observed based on the cerebellar hemisphere stimulated and the type of data presented. We observed that participants were significantly less accurate on a verbal version of a Sternberg task after stimulation to the right cerebellar hemisphere when compared to left hemisphere stimulation. Performance on a visual Sternberg task was unaffected by stimulation of either hemisphere. We discuss our results in the context of prior studies that have used cerebellar stimulation to investigate working memory and highlight the cerebellar role in phonological encoding. PMID:24338673

  4. [Memory transfer in cerebellar motor learning].

    PubMed

    Nagao, Soichi

    2012-01-01

    Most of our motor skills are acquired through learning. Experiments of gain adaptation of ocular reflexes have consistently suggested that the memory of adaptation is initially formed in the cerebellar cortex, and is transferred to the cerebellar (vestibular) nuclei for consolidation to long-term memory after repetitions of training. We have recently developed a new system to evaluate the motor learning in human subjects using prism adaptation of hand reaching movement, by referring to the prism adaptation of dart throwing of Martin et al. (1996). In our system, the subject views the small target presented in the touch-panel screen, and touches it with his/her finger without direct visual feedback. After 15-30 trials of touching wearing prisms, an adaptation occurs in healthy subjects: they became able to touch the target correctly. Meanwhile, such an adaptation was impaired in patients of cerebellar disease. We have proposed a model of human prism adaptation that the memory of adaptation is initially encoded in the cerebellar cortex, and is later transferred to the cerebellar nuclei after repetitions of training. The memory in the cerebellar cortex may be formed and extinguished independently of the memory maintained in the cerebellar nuclei, and these two memories work cooperatively. PMID:23196495

  5. Cerebellar Motor Function in Spina Bifida Meningomyelocele

    PubMed Central

    Dennis, Maureen; Salman, Michael S.; Juranek, Jenifer; Fletcher, Jack M.

    2010-01-01

    Spina bifida meningomyelocele (SBM), a congenital neurodevelopmental disorder, involves dysmorphology of the cerebellum, and its most obvious manifestations are motor deficits. This paper reviews cerebellar neuropathology and motor function across several motor systems well studied in SBM in relation to current models of cerebellar motor and timing function. Children and adults with SBM have widespread motor deficits in trunk, upper limbs, eyes, and speech articulators that are broadly congruent with those observed in adults with cerebellar lesions. The structure and function of the cerebellum are correlated with a range of motor functions. While motor learning is generally preserved in SBM, those motor functions requiring predictive signals and precise calibration of the temporal features of movement are impaired, resulting in deficits in smooth movement coordination as well as in the classical cerebellar triad of dysmetria, ataxia, and dysarthria. That motor function in individuals with SBM is disordered in a manner phenotypically similar to that in adult cerebellar lesions, and appears to involve similar deficits in predictive cerebellar motor control, suggests that age-based cerebellar motor plasticity is limited in individuals with this neurodevelopmental disorder. PMID:20652468

  6. Reference energy-altitude descent guidance: Simulator evaluation. [aircraft descent and fuel conservation

    NASA Technical Reports Server (NTRS)

    Abbot, K. H.; Knox, C. E.

    1985-01-01

    Descent guidance was developed to provide a pilot with information to ake a fuel-conservative descent and cross a designated geographical waypoint at a preselected altitude and airspeed. The guidance was designed to reduce fuel usage during the descent and reduce the mental work load associated with planning a fuel-conservative descent. A piloted simulation was conducted to evaluate the operational use of this guidance concept. The results of the simulation tests show that the use of the guidance reduced fuel consumption and mental work load during the descent. Use of the guidance also decreased the airspeed error, but had no effect on the altitude error when the designated waypoint was crossed. Physical work load increased with the use of the guidance, but remained well within acceptable levels. The pilots found the guidance easy to use as presented and reported that it would be useful in an operational environment.

  7. Paraneoplastic cerebellar ataxia and the paraneoplastic syndromes

    PubMed Central

    Afzal, Sadaf; Recio, Maria

    2015-01-01

    Paraneoplastic cerebellar ataxia, also known as paraneoplastic cerebellar degeneration, is one of the wide array of paraneoplastic neurological syndromes in which neurological symptoms are indirectly caused by an underlying malignancy, most commonly gynecological, breast, or lung cancer or Hodgkin's lymphoma. We describe a patient with severe cerebellar dysfunction attributed to a paraneoplastic neurological syndrome. The case highlights the need to look for paraneoplastic syndromes—both to discover malignancies early, at a treatable stage, and, as in our case, to address very distressing symptoms for the patient's relief even if the malignancy is not curable. PMID:25829659

  8. Toll-like receptor 4 gene (TLR4), but not TLR2, polymorphisms modify the risk of tonsillar disease due to Streptococcus pyogenes and Haemophilus influenzae.

    PubMed

    Liadaki, Kyriaki; Petinaki, Efthimia; Skoulakis, Charalampos; Tsirevelou, Paraskeui; Klapsa, Dimitra; Germenis, Anastasios E; Speletas, Matthaios

    2011-02-01

    Tonsillar disease (recurrent tonsillitis and/or tonsillar hypertrophy) is one of the most common human disorders, with Streptococcus pyogenes (group A beta-hemolytic streptococcus [GAS]) and Haemophilus influenzae representing the most common pathogens. Until now, no study has investigated why some individuals are more susceptible to tonsillar infections caused by specific bacteria than others. The aim of this study was to uncover possible associations between common Toll-like receptor gene (TLR) polymorphisms and tonsillar disease. The TLR2-R753Q, TLR4-D299G, and TLR4-T399I polymorphisms were determined in a cohort of 327 patients subjected to tonsillectomy due to recurrent tonsillitis (n = 245) and tonsillar hypertrophy (n = 82) and 245 healthy bone marrow donors. Associations of the aforementioned polymorphisms with the isolated bacterial strains after tonsillectomy were also investigated. Interestingly, carriers of the TLR4 polymorphisms displayed an approximately 3-fold increased risk for GAS infections (for TLR4-D299G, odds ratio [OR] = 2.81, 95% confidence interval [CI] = 1.16 to 6.79, P = 0.038; for TLR4-T399I, OR = 3.01, 95% CI = 1.29 to 7.02, P = 0.023), and this association was more profound in patients with recurrent tonsillitis. On the contrary, the presence of the TLR4-T399I polymorphism was associated with a 2-fold decreased risk of Haemophilus influenzae carriage (OR = 0.38, 95% CI = 0.15 to 0.96, P = 0.038). In the end, no significant differences were observed, considering the genotype and allele frequencies of the above-mentioned polymorphisms, between patients and controls. Our findings indicate that, regarding tonsillar infections, TLR4 polymorphisms predispose individuals to GAS infection, while they are protective against Haemophilus influenzae infection. This result further elucidates the role that host immune genetic variations might play in the susceptibility to common infections and tonsillar disease. PMID:21159925

  9. Entry, Descent, and Landing With Propulsive Deceleration

    NASA Technical Reports Server (NTRS)

    Palaszewski, Bryan

    2012-01-01

    The future exploration of the Solar System will require innovations in transportation and the use of entry, descent, and landing (EDL) systems at many planetary landing sites. The cost of space missions has always been prohibitive, and using the natural planetary and planet s moons atmospheres for entry, descent, and landing can reduce the cost, mass, and complexity of these missions. This paper will describe some of the EDL ideas for planetary entry and survey the overall technologies for EDL that may be attractive for future Solar System missions.

  10. Eyeblink conditioning indicates cerebellar abnormality in dyslexia

    Microsoft Academic Search

    Roderick I. Nicolson; Irene Daum; Markus M. Schugens; Angela J. Fawcett; Adelheid Schulz

    2002-01-01

    There is increasing evidence that cerebellar deficit may be a causal factor in dyslexia. The cerebellum is considered to be\\u000a the major structure involved in classical conditioning of the eyeblink response. In a direct test of cerebellar function in\\u000a learning, 13 dyslexic participants (mean age 19.5 years) and 13 control participants matched for age and IQ undertook an eyeblink\\u000a conditioning experiment

  11. Pasteurellaceae isolated from tonsillar samples of commercially-reared American bison (Bison bison).

    PubMed Central

    Ward, A C; Dyer, N W; Fenwick, B W

    1999-01-01

    As commercial producers of American bison (Bison bison) become more numerous, concerns relative to bison health management increase. Since loss due to respiratory disease associated with Pasteurella and related Pasteurellaceae is a major concern for cattle producers, a study was conducted to determine what types of Pasteurellaceae are carried by bison to evaluate the potential of pneumonic pasteurellosis in bison herds where management practices are comparable to those used for cattle. Tonsillar biopsies, collected in May (n = 29) and August (n = 25) 1997 from 24- to 30-month-old bison bulls, at the time of slaughter were cultured for Pasteurellaceae. Pasteurella spp. were isolated from all the samples collected in May. These included isolates identified as P. haemolytica, trehalosi, testudinis, and multocida subsp. multocida a and multocida b. Actinobacillus spp. and Haemophilus somnus were also isolated from some samples. Pasteurella spp., haemolytica, trehalosi, and multocida subsp. multocida a, multocida b and septica, plus 2 nonspeciated indole-positive biotypes, U2 and U16, were isolated from the second group of tonsil samples. Most of these organisms, including P. haemolytica, P. multocida subsp., and H. somnus are associated with disease in domestic livestock and should be regarded as potential pathogens for bison, particularly in animals which become stressed by management practices commonly used with cattle such as herding, crowding, and shipping. Images Figure 1. PMID:10480456

  12. Histopathologic Predictors of Lymph Node Metastasis and Prognosis in Tonsillar Squamous Cell Carcinoma

    PubMed Central

    Lee, Dong Jin; Kwon, Mi Jung; Nam, Eun Sook; Kwon, Ji Hyun; Kim, Jin Hwan; Rho, Young-Soo

    2013-01-01

    Background Risk factors for lymph node metastasis in tonsillar squamous cell carcinoma (TSCC) need to be established to determine the degree of surgery required to achieve high curative rates. However, little is known currently about the histopathological features predicting prognosis, specifically in TSCC. Methods This study included 53 patients who underwent surgical resection with neck dissection. Clinicopathological factors investigated included age, gender, alcohol use, tobacco consumption, tumor stage, adjacent structure involvement, cell differentiation, squamous dysplasia, in situ carcinoma associated with primary invasive cancer, carcinoma in situ skip lesions, necrosis, invasive front, depth of invasion, and lymphatic, muscle, or perineural invasion. Results Contralateral cervical metastasis was associated with higher T stages and soft palate invasion. Lymphatic and muscle invasion were associated with ipsilateral cervical metastasis. Advanced T stage, invasion to the base of tongue, and skip lesions were associated with decreased disease-free survival. Advanced T stage and skip lesions were associated with worse overall survival. Conclusions Advanced T stage and soft palate invasion may predict a high risk of contralateral nodal metastasis. T stage and skip lesion are worse prognostic factors in TSCC and should be commented in pathology reports. PMID:23837012

  13. Possible role of nano-sized particles in chronic tonsillitis and tonsillar carcinoma: a pilot study.

    PubMed

    Zeleník, Karol; Kukutschová, Jana; Dvo?á?ková, Jana; Bielniková, Hana; Peikertová, Pavlína; Cábalová, Lenka; Komínek, Pavel

    2013-02-01

    This study aimed to evaluate the palatine tonsils of patients with chronic tonsillitis and spinocellular carcinoma to determine the presence of nano-sized particles. Tonsil samples from adult patients with chronic tonsillitis and spinocellular carcinoma of the palatine tonsil were dried and analyzed using a scanning electron microscope with the X-ray microprobe of an energy-dispersive spectroscope. Demographic data and smoking histories were obtained. The principal metals found in almost all tissues analyzed were iron, chromium, nickel, aluminum, zinc, and copper. No significant difference in elemental composition was found between the group of patients with chronic tonsillitis and the group with spinocellular carcinoma of the palatine tonsil. Likewise, no significant difference was found between the group of smokers and the group of nonsmokers. The presence of various micro- and nano-sized metallic particles in human tonsils was confirmed. These particles may potentially cause an inflammatory response as well as neoplastic changes in human palatine tonsils similar to those occurring in the lungs. Further and more detailed studies addressing this issue, including studies designed to determine the chemical form of the metals detected, studies devoted to quantitative analysis, biokinetics, and to the degradation and elimination of nanoparticles are needed for a more detailed prediction of the relation between the diagnosis and the presence of specific metal nanoparticles in tonsillar tissue. PMID:22678622

  14. Targeting the red nucleus for cerebellar tremor.

    PubMed

    Lefranc, M; Manto, M; Merle, P; Tir, M; Montpellier, D; Constant, J-M; Le Gars, D; Macron, J-M; Krystkowiak, P

    2014-06-01

    Deep brain stimulation of the thalamus (and especially the ventral intermediate nucleus) does not significantly improve a drug-resistant, disabling cerebellar tremor. The dentato-rubro-olivary tract (Guillain-Mollaret triangle, including the red nucleus) is a subcortical loop that is critically involved in tremor genesis. We report the case of a 48-year-old female patient presenting with generalized cerebellar tremor caused by alcohol-related cerebellar degeneration. Resistance to pharmacological treatment and the severity of the symptoms prompted us to investigate the effects of bilateral deep brain stimulation of the red nucleus. Intra-operative microrecordings of the red nucleus revealed intense, irregular, tonic background activity but no rhythmic components that were synchronous with upper limb tremor. The postural component of the cerebellar tremor disappeared during insertion of the macro-electrodes and for a few minutes after stimulation, with no changes in the intentional (kinetic) component. Stimulation per se did not reduce postural or intentional tremor and was associated with dysautonomic symptoms (the voltage threshold for which was inversed related to the stimulation frequency). Our observations suggest that the red nucleus is (1) an important centre for the genesis of cerebellar tremor and thus (2) a possible target for drug-refractory tremor. Future research must determine how neuromodulation of the red nucleus can best be implemented in patients with cerebellar degeneration. PMID:24415178

  15. Consensus paper: radiological biomarkers of cerebellar diseases.

    PubMed

    Baldarçara, Leonardo; Currie, Stuart; Hadjivassiliou, M; Hoggard, Nigel; Jack, Allison; Jackowski, Andrea P; Mascalchi, Mario; Parazzini, Cecilia; Reetz, Kathrin; Righini, Andrea; Schulz, Jörg B; Vella, Alessandra; Webb, Sara Jane; Habas, Christophe

    2015-04-01

    Hereditary and sporadic cerebellar ataxias represent a vast and still growing group of diseases whose diagnosis and differentiation cannot only rely on clinical evaluation. Brain imaging including magnetic resonance (MR) and nuclear medicine techniques allows for characterization of structural and functional abnormalities underlying symptomatic ataxias. These methods thus constitute a potential source of radiological biomarkers, which could be used to identify these diseases and differentiate subgroups of them, and to assess their severity and their evolution. Such biomarkers mainly comprise qualitative and quantitative data obtained from MR including proton spectroscopy, diffusion imaging, tractography, voxel-based morphometry, functional imaging during task execution or in a resting state, and from SPETC and PET with several radiotracers. In the current article, we aim to illustrate briefly some applications of these neuroimaging tools to evaluation of cerebellar disorders such as inherited cerebellar ataxia, fetal developmental malformations, and immune-mediated cerebellar diseases and of neurodegenerative or early-developing diseases, such as dementia and autism in which cerebellar involvement is an emerging feature. Although these radiological biomarkers appear promising and helpful to better understand ataxia-related anatomical and physiological impairments, to date, very few of them have turned out to be specific for a given ataxia with atrophy of the cerebellar system being the main and the most usual alteration being observed. Consequently, much remains to be done to establish sensitivity, specificity, and reproducibility of available MR and nuclear medicine features as diagnostic, progression and surrogate biomarkers in clinical routine. PMID:25382714

  16. Evolution of the cerebellar cortex: the selective expansion of prefrontal-projecting cerebellar lobules.

    PubMed

    Balsters, J H; Cussans, E; Diedrichsen, J; Phillips, K A; Preuss, T M; Rilling, J K; Ramnani, N

    2010-02-01

    It has been suggested that interconnected brain areas evolve in tandem because evolutionary pressures act on complete functional systems rather than on individual brain areas. The cerebellar cortex has reciprocal connections with both the prefrontal cortex and motor cortex, forming independent loops with each. Specifically, in capuchin monkeys cerebellar cortical lobules Crus I and Crus II connect with prefrontal cortex, whereas the primary motor cortex connects with cerebellar lobules V, VI, VIIb, and VIIIa. Comparisons of extant primate species suggest that the prefrontal cortex has expanded more than cortical motor areas in human evolution. Given the enlargement of the prefrontal cortex relative to motor cortex in humans, our hypothesis would predict corresponding volumetric increases in the parts of the cerebellum connected to the prefrontal cortex, relative to cerebellar lobules connected to the motor cortex. We tested the hypothesis by comparing the volumes of cerebellar lobules in structural MRI scans in capuchins, chimpanzees and humans. The fractions of cerebellar volume occupied by Crus I and Crus II were significantly larger in humans compared to chimpanzees and capuchins. Our results therefore support the hypothesis that in the cortico-cerebellar system, functionally related structures evolve in concert with each other. The evolutionary expansion of these prefrontal-projecting cerebellar territories might contribute to the evolution of the higher cognitive functions of humans. PMID:19857577

  17. Modified descent-projection method for solving variational inequalities

    Microsoft Academic Search

    Abdellah Bnouhachem; Muhammad Aslam Noor; Mohamed Khalfaoui

    2007-01-01

    In this paper, we propose a modified descent-projection method for solving variational inequalities. The method makes use of a descent direction to produce the new iterate and can be viewed as an improvement of the descent-projection method by using a new step size. Under certain conditions, the global convergence of the proposed method is proved. In order to demonstrate the

  18. Perceptron Learning with Random Coordinate Descent

    Microsoft Academic Search

    Ling Li

    2005-01-01

    A perceptron is a linear threshold classier that separates examples with a hyperplane. It is perhaps the simplest learning model that is used standalone. In this paper, we propose a family of random coordinate descent algorithms for perceptron learning on binary classication problems. Un- like most perceptron learning algorithms, which require smooth cost functions, our algorithms directly minimize the training

  19. Learning to rank using gradient descent

    Microsoft Academic Search

    Christopher J. C. Burges; Tal Shaked; Erin Renshaw; Ari Lazier; Matt Deeds; Nicole Hamilton; Gregory N. Hullender

    2005-01-01

    We investigate using gradient descent meth- ods for learning ranking functions; we pro- pose a simple probabilistic cost function, and we introduce RankNet, an implementation of these ideas using a neural network to model the underlying ranking function. We present test results on toy data and on data from a commercial internet search engine.

  20. Ka-Band Radar Terminal Descent Sensor

    NASA Technical Reports Server (NTRS)

    Pollard, Brian; Berkun, Andrew; Tope, Michael; Andricos, Constantine; Okonek, Joseph; Lou, Yunling

    2007-01-01

    The terminal descent sensor (TDS) is a radar altimeter/velocimeter that improves the accuracy of velocity sensing by more than an order of magnitude when compared to existing sensors. The TDS is designed for the safe planetary landing of payloads, and may be used in helicopters and fixed-wing aircraft requiring high-accuracy velocity sensing

  1. Descent Assisted Split Habitat Lunar Lander Concept

    NASA Technical Reports Server (NTRS)

    Mazanek, Daniel D.; Goodliff, Kandyce; Cornelius, David M.

    2008-01-01

    The Descent Assisted Split Habitat (DASH) lunar lander concept utilizes a disposable braking stage for descent and a minimally sized pressurized volume for crew transport to and from the lunar surface. The lander can also be configured to perform autonomous cargo missions. Although a braking-stage approach represents a significantly different operational concept compared with a traditional two-stage lander, the DASH lander offers many important benefits. These benefits include improved crew egress/ingress and large-cargo unloading; excellent surface visibility during landing; elimination of the need for deep-throttling descent engines; potentially reduced plume-surface interactions and lower vertical touchdown velocity; and reduced lander gross mass through efficient mass staging and volume segmentation. This paper documents the conceptual study on various aspects of the design, including development of sortie and outpost lander configurations and a mission concept of operations; the initial descent trajectory design; the initial spacecraft sizing estimates and subsystem design; and the identification of technology needs

  2. Focal appearance of cerebellar torpedoes associated with discrete lesions in the cerebellar white matter.

    PubMed

    Takahashi, N; Iwatsubo, T; Nakano, I; Machinami, R

    1992-01-01

    Cerebellar torpedoes, unique fusiform swellings of Purkinje cell axons within the granular layer, have been known to occur sparsely associated with diffuse cerebellar changes. This report describes, in three human autopsy cases with focal necrotic lesions in the cerebellar white matter, torpedoes which were essentially confined to the cerebellar cortex overlying the lesions. Purkinje cells in the same region showed no recognizable change, but were obviously decreased in number. The location of the necrotic lesions was such that they may well have severed Purkinje cell axons projecting into the deeply located cerebellar nuclei from the torpedo-carrying cortex. These findings indicate that damage to Purkinje cell axons, even if it occurs far away from the cell bodies, may have a critical influence upon the metabolism of Purkinje cells and play an important role in the formation of torpedoes. PMID:1523970

  3. Locomotor patterns in cerebellar ataxia.

    PubMed

    Martino, G; Ivanenko, Y P; Serrao, M; Ranavolo, A; d'Avella, A; Draicchio, F; Conte, C; Casali, C; Lacquaniti, F

    2014-12-01

    Several studies have demonstrated how cerebellar ataxia (CA) affects gait, resulting in deficits in multijoint coordination and stability. Nevertheless, how lesions of cerebellum influence the locomotor muscle pattern generation is still unclear. To better understand the effects of CA on locomotor output, here we investigated the idiosyncratic features of the spatiotemporal structure of leg muscle activity and impairments in the biomechanics of CA gait. To this end, we recorded the electromyographic (EMG) activity of 12 unilateral lower limb muscles and analyzed kinematic and kinetic parameters of 19 ataxic patients and 20 age-matched healthy subjects during overground walking. Neuromuscular control of gait in CA was characterized by a considerable widening of EMG bursts and significant temporal shifts in the center of activity due to overall enhanced muscle activation between late swing and mid-stance. Patients also demonstrated significant changes in the intersegmental coordination, an abnormal transient in the vertical ground reaction force and instability of limb loading at heel strike. The observed abnormalities in EMG patterns and foot loading correlated with the severity of pathology [International Cooperative Ataxia Rating Scale (ICARS), a clinical ataxia scale] and the changes in the biomechanical output. The findings provide new insights into the physiological role of cerebellum in optimizing the duration of muscle activity bursts and the control of appropriate foot loading during locomotion. PMID:25185815

  4. Enlarged cerebellar vermis in Williams syndrome J. Eric Schmitta

    E-print Network

    Bellugi, Ursula

    Enlarged cerebellar vermis in Williams syndrome J. Eric Schmitta , Stephan Elieza , Ilana S Williams syndrome (WMS) is a rare genetic disorder characterized by relative preservations of language. Keywords: Williams syndrome; Cerebellar vermis; Neurogenetics; MRI; Chromosome 7 1. Introduction It has

  5. 21 CFR 882.5820 - Implanted cerebellar stimulator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...cerebellar stimulator is a device used to stimulate electrically a patient's cerebellar cortex for the treatment of intractable epilepsy, spasticity, and some movement disorders. The stimulator consists of an implanted receiver with electrodes that are...

  6. Genetics Home Reference: Autosomal recessive cerebellar ataxia type 1

    MedlinePLUS

    ... disorder catalog Conditions > Autosomal recessive cerebellar ataxia type 1 (often shortened to ARCA1 ) On this page: Description ... What is ARCA1? Autosomal recessive cerebellar ataxia type 1 (ARCA1) is a condition characterized by progressive problems ...

  7. Metabolic anatomy of paraneoplastic cerebellar degeneration

    SciTech Connect

    Anderson, N.E.; Posner, J.B.; Sidtis, J.J.; Moeller, J.R.; Strother, S.C.; Dhawan, V.; Rottenberg, D.A.

    1988-06-01

    Eleven patients with acquired cerebellar degeneration (10 of whom had paraneoplastic cerebellar degeneration (PCD)) were evaluated using neuropsychological tests and /sup 18/F-fluorodeoxyglucose/positron emission tomography to (1) quantify motor, cognitive, and metabolic abnormalities; (2) determine if characteristic alterations in the regional cerebral metabolic rate for glucose (rCMRGlc) are associated with PCD; and (3) correlate behavioral and metabolic measures of disease severity. Eighteen volunteer subjects served as normal controls. Although some PCD neuropsychological test scores were abnormal, these results could not, in general, be dissociated from the effects of dysarthria and ataxia. rCMRGlc was reduced in patients with PCD (versus normal control subjects) in all regions except the brainstem. Analysis of patient and control rCMRGlc data using a mathematical model of regional metabolic interactions revealed two metabolic pattern descriptors, SSF1 and SSF2, which distinguished patients with PCD from normal control subjects; SSF2, which described a metabolic coupling between cerebellum, cuneus, and posterior temporal, lateral frontal, and paracentral cortex, correlated with quantitative indices of cerebellar dysfunction. Our inability to document substantial intellectual impairment in 7 of 10 patients with PCD contrasts with the 50% incidence of dementia in PCD reported by previous investigators. Widespread reductions in PCD rCMRGlc may result from the loss of cerebellar efferents to thalamus and forebrain structures, a reverse cerebellar diaschisis.

  8. Cerebellar modules operate at different frequencies

    PubMed Central

    Zhou, Haibo; Lin, Zhanmin; Voges, Kai; Ju, Chiheng; Gao, Zhenyu; Bosman, Laurens WJ; Ruigrok, Tom JH; Hoebeek, Freek E

    2014-01-01

    Due to the uniform cyto-architecture of the cerebellar cortex, its overall physiological characteristics have traditionally been considered to be homogeneous. In this study, we show in awake mice at rest that spiking activity of Purkinje cells, the sole output cells of the cerebellar cortex, differs between cerebellar modules and correlates with their expression of the glycolytic enzyme aldolase C or zebrin. Simple spike and complex spike frequencies were significantly higher in Purkinje cells located in zebrin-negative than zebrin-positive modules. The difference in simple spike frequency persisted when the synaptic input to, but not intrinsic activity of, Purkinje cells was manipulated. Blocking TRPC3, the effector channel of a cascade of proteins that have zebrin-like distribution patterns, attenuated the simple spike frequency difference. Our results indicate that zebrin-discriminated cerebellar modules operate at different frequencies, which depend on activation of TRPC3, and that this property is relevant for all cerebellar functions. DOI: http://dx.doi.org/10.7554/eLife.02536.001 PMID:24843004

  9. Alcohol Excites Cerebellar Golgi Cells by Inhibiting Paolo Botta1

    E-print Network

    De Schutter, Erik

    Alcohol Excites Cerebellar Golgi Cells by Inhibiting the Na+ /K+ ATPase Paolo Botta1 , Fabio M Simo of Theoretical Neurobiology, University of Antwerp, Wilrijk, Belgium Alcohol-induced alterations of cerebellar worldwide. Cognitive deficits associated with alcoholism are also a consequence of cerebellar dysfunction

  10. The metamorphosis of the developing cerebellar microcircuit

    PubMed Central

    van Welie, Ingrid; Smith, Ikuko T; Watt, Alanna J

    2011-01-01

    The cerebellar cortical circuit with its organized and repetitive structure provides an excellent model system for studying how brain circuits are formed during development. The emergence of the mature brain requires that appropriate synaptic connections are formed and refined, which in the rodent cerebellum occurs primarily during the first three postnatal weeks. Developing circuits typically differ substantially from their mature counterparts, which suggests that development may not simply involve synaptic refinement, but rather involves restructuring of key synaptic components and network connections, in a manner reminiscent of metamorphosis. Here, we discuss recent evidence that, taken together, suggests that transient features of developing cerebellar synapses may act to coordinate network activity, and thereby shape the development of the cerebellar microcircuit. PMID:21353528

  11. Specific influences of cerebellar dysfunctions on gait.

    PubMed

    Ilg, Winfried; Golla, Heidrun; Thier, Peter; Giese, Martin A

    2007-03-01

    Cerebellar ataxic gait is characterized by unsteady movements and variable gait patterns. Previous studies have successfully identified pathological changes of balance-related gait parameters. However, it has been difficult to demonstrate deficits of joint coordination and the control of limb dynamics. This has motivated the hypothesis that cerebellar ataxic gait might be affected predominantly by balance impairments. We investigated the influences of different types of cerebellar dysfunction on the gait patterns of patients suffering from degenerative cerebellar disease (13 patients, five females, 50.4 +/- 14.4 years). Walking patterns were quantitatively analysed combining standard gait measures and novel measures for the characterization of the spatial and the temporal variability of intra-joint coordination patterns. The temporal variability of gait patterns was significantly correlated with a subscale of the clinical ataxia scale (ICARS) that rates deficits of the control of limb dynamics and intra-limb coordination for goal-directed movements. This suggests that common cerebellar mechanisms might be involved in coordination during voluntary limb control and ataxic gait. The tested standard gait parameters correlated predominantly with clinical measures for balance-related abnormalities. These results imply that ataxic gait is influenced by both balance-related impairments and deficits related to limb control and intra-limb coordination. Applying the same analysis to gait patterns from patients with peripheral vestibular failure (six patients, four females, 47.8 +/- 14.3 years) and Parkinson's disease (eight patients, two females, 60.7 +/- 10.6 years), we found comparable abnormalities in balance-related gait parameters and general gait variability, but significantly lower increases of temporal variability. This implies that increased temporal variability of intra-limb coordination is a specific characteristic of cerebellar dysfunction, which does not arise for other movement disorders that also cause balance deficits and increased gait variability. PMID:17287287

  12. A gentle Hessian for efficient gradient descent

    Microsoft Academic Search

    Ronan Collobert; Samy Bengio

    2004-01-01

    Several second-order optimization methods for gradient descent algorithms have been proposed over the years, but they usually need to compute the inverse of the Hessian of the cost function (or an approximation of this inverse) during training. In most cases, this leads to an O(n2) cost in time and space per iteration, where n is the number of parameters, which

  13. Cerebellar ataxia: quantitative assessment and cybernetic interpretation.

    PubMed

    Sanguineti, Vittorio; Morasso, Pietro G; Baratto, Luigi; Brichetto, Giampaolo; Luigi Mancardi, Giovanni; Solaro, Claudio

    2003-04-01

    To assess neuromotor disorders clinicians often rely on rating scales. Unfortunately, these scales lack the sensitivity and accuracy needed to detect the small changes in motor coordination that reflect the clinical progression of the disease on the basis of which treatment programmes can be adjusted. As a contribution to this topic, the present paper proposes a straightforward kinematic and kinetic analysis of reaching movements of patients with cerebellar ataxia in conjunction with a cybernetic interpretation of the data. The aim of the approach is to capture key deficits in the underlying motor control processes. We suggest that cerebellar ataxia may be characterized by defective feedforward control. PMID:12667749

  14. Tonsillar metastasis of small cell lung cancer in a patient with idiopathic pulmonary fibrosis: a case report.

    PubMed

    Kim, Eo Jin; Kim, So Ri; Jin Gang, Su; Park, Seung Yong; Han, Young Min; Lee, Yong Chul

    2015-02-01

    Small cell lung cancer (SCLC) metastasizes widely, but palatine tonsil is an extremely unusual site for metastasis. Idiopathic pulmonary fibrosis (IPF) is associated with increased risk of lung cancer. However, the most common histological findings among patients of lung cancer with IPF are known as non-SCLC such as adenocarcinoma and squamous cell carcinoma. In addition, the majority of them are located in IPF-associated fibrotic peripheral lesions.A 77-year-old man visited for 1-month persistent cough and dyspnea, with inspiratory dry crackles on both lower lung fields and a large oval mass in his throat. Chest computed tomography revealed 2 masses in the left lower lobe, 1 mass in the right upper lobe, and multiple enlarged mediastinal lymph nodes of the lung accompanying with IPF, which were diagnosed as SCLC pathologically. Very interestingly, the tonsillar mass was also confirmed as the metastatic lesion of SCLC. Chemotherapy for SCLC and medical treatment for IPF were applied. However, in following-up, he expired due to respiratory failure by an acute exacerbation of IPF 3 months after the diagnosis.In this current report, we describe, for the first time, a case of tonsillar metastasis of SCLC with IPF detected simultaneously in a 77-year-old man. PMID:25700331

  15. The Cerebellar Mutism Syndrome and Its Relation to Cerebellar Cognitive Function and the Cerebellar Cognitive Affective Disorder

    ERIC Educational Resources Information Center

    Wells, Elizabeth M.; Walsh, Karin S.; Khademian, Zarir P.; Keating, Robert F.; Packer, Roger J.

    2008-01-01

    The postoperative cerebellar mutism syndrome (CMS), consisting of diminished speech output, hypotonia, ataxia, and emotional lability, occurs after surgery in up to 25% of patients with medulloblastoma and occasionally after removal of other posterior fossa tumors. Although the mutism is transient, speech rarely normalizes and the syndrome is…

  16. Evidence of Bacterial Biofilms among Infected and Hypertrophied Tonsils in Correlation with the Microbiology, Histopathology, and Clinical Symptoms of Tonsillar Diseases

    PubMed Central

    Alasil, Saad Musbah; Omar, Rahmat; Yusof, Mohd Yasim; Dhabaan, Ghulam N.

    2013-01-01

    Diseases of the tonsils are becoming more resistant to antibiotics due to the persistence of bacteria through the formation of biofilms. Therefore, understanding the microbiology and pathophysiology of such diseases represent an important step in the management of biofilm-related infections. We have isolated the microorganisms, evaluated their antimicrobial susceptibility, and detected the presence of bacterial biofilms in tonsillar specimens in correlation with the clinical manifestations of tonsillar diseases. Therefore, a total of 140 palatine tonsils were collected from 70 patients undergoing tonsillectomy at University Malaya Medical Centre. The most recovered isolate was Staphylococcus aureus (39.65%) followed by Haemophilus influenzae (18.53%). There was high susceptibility against all selected antibiotics except for cotrimoxazole. Bacterial biofilms were detected in 60% of patients and a significant percentage of patients demonstrated infection manifestation rather than obstruction. In addition, an association between clinical symptoms like snore, apnea, nasal obstruction, and tonsillar hypertrophy was found to be related to the microbiology of tonsils particularly to the presence of biofilms. In conclusion, evidence of biofilms in tonsils in correlation with the demonstrated clinical symptoms explains the recalcitrant nature of tonsillar diseases and highlights the importance of biofilm's early detection and prevention towards better therapeutic management of biofilm-related infections. PMID:24454384

  17. EMG analysis of patients with cerebellar deficits

    Microsoft Academic Search

    M Hallett; B T Shahani; R R Young

    1975-01-01

    EMGs from biceps and triceps were recorded during stereotyped elbow flexion tasks performed by 20 patients fulfilling clinical criteria for 'cerebellar deficits' and the data were compared with previously established normal standards. In a fast flexion task, 15 of 18 patients showed prolongation of the initial biceps and\\/or triceps components, and it is suggested that this abnormality might be an

  18. Developmental dyslexia: the cerebellar deficit hypothesis

    Microsoft Academic Search

    Roderick I Nicolson; Angela J Fawcett; Paul Dean

    2001-01-01

    Surprisingly, the problems faced by many dyslexic children are by no means confined to reading and spelling. There appears to be a general impairment in the ability to perform skills automatically, an ability thought to be dependent upon the cerebellum. Specific behavioural and neuroimaging tests reviewed here indicate that dyslexia is indeed associated with cerebellar impairment in about 80% of

  19. Remote cerebellar hemorrhage after cervical spinal surgery.

    PubMed

    Huang, Po-Hsien; Wu, Jau-Ching; Cheng, Henrich; Shih, Yang-Hsin; Huang, Wen-Cheng

    2013-10-01

    Remote cerebellar hemorrhage (RCH) is an unpredictable and rare complication of spinal surgery. We report five cases of RCH following cervical spinal surgery, and summarize another seven similar cases from the literature. Dural opening with cerebrospinal fluid (CSF) hypovolemia seems to be an important factor contributing to RCH following cervical spinal surgery. As other authors have proposed, surgical positioning may be another factor contributing to RCH. RCH is thought to be hemorrhagic venous infarction, resulting from the stretching occlusion of the superior cerebellar vein by the cerebellar sag effect. Either intraoperative CSF loss or a postoperative CSF leak from drainage may cause cerebellar sag, further resulting in RCH. RCH is usually self-limiting, and most patients with RCH have an optimal outcome after conservative treatment. Severe cases that involved surgical intervention because of evidence of brainstem compression or hydrocephalus also had acceptable outcomes, compared to spontaneous CH. It has been suggested that one way to prevent RCH is to avoid extensive perioperative loss of CSF, by paying attention to surgical positioning during spinal surgery. We also underline the importance of early diagnosis and CSF expansion in the early treatment of RCH. PMID:23746536

  20. Cerebellar syndrome following neuroleptic induced heat stroke.

    PubMed Central

    Lefkowitz, D; Ford, C S; Rich, C; Biller, J; McHenry, L C

    1983-01-01

    We report a patient in whom extreme hyperthermia, rhabdomyolysis, acute renal failure and a residual pancerebellar syndrome occurred while taking a combination of perphenazine and amitriptyline. We postulate that impaired thermoregulation due to psychotropic drugs was responsible for the development of heat stroke and that the cerebellar syndrome resulted directly from the elevated temperature. PMID:6842224

  1. Regression Analysis of Top of Descent Location for Idle-thrust Descents

    NASA Technical Reports Server (NTRS)

    Stell, Laurel; Bronsvoort, Jesper; McDonald, Greg

    2013-01-01

    In this paper, multiple regression analysis is used to model the top of descent (TOD) location of user-preferred descent trajectories computed by the flight management system (FMS) on over 1000 commercial flights into Melbourne, Australia. The independent variables cruise altitude, final altitude, cruise Mach, descent speed, wind, and engine type were also recorded or computed post-operations. Both first-order and second-order models are considered, where cross-validation, hypothesis testing, and additional analysis are used to compare models. This identifies the models that should give the smallest errors if used to predict TOD location for new data in the future. A model that is linear in TOD altitude, final altitude, descent speed, and wind gives an estimated standard deviation of 3.9 nmi for TOD location given the trajec- tory parameters, which means about 80% of predictions would have error less than 5 nmi in absolute value. This accuracy is better than demonstrated by other ground automation predictions using kinetic models. Furthermore, this approach would enable online learning of the model. Additional data or further knowl- edge of algorithms is necessary to conclude definitively that no second-order terms are appropriate. Possible applications of the linear model are described, including enabling arriving aircraft to fly optimized descents computed by the FMS even in congested airspace. In particular, a model for TOD location that is linear in the independent variables would enable decision support tool human-machine interfaces for which a kinetic approach would be computationally too slow.

  2. Clinical features in patients with excessive perineal descent.

    PubMed

    Mackle, E J; Parks, T G

    1989-04-01

    We have found excessive perineal descent to be associated with a variety of anorectal problems and have reviewed the clinical features in 29 patients who were noted to have excessive perineal descent as measured by perineometer. The condition mostly occurs in women and is usually associated with straining at stool, rectal bleeding, mucus discharge, perineal or abdominal pain and urinary incontinence. PMID:2724218

  3. Large-Scale Matrix Factorization with Distributed Stochastic Gradient Descent

    E-print Network

    of columns, and billions of nonzero elements. Our approach rests on stochastic gradient descent (SGD), an iterative stochastic optimization algorithm. Based on a novel "stratified" variant of SGD, we obtain a new Gradient Descent The goal of SGD is to find the value k (k 1) that minimizes a given loss L

  4. Stochastic Gradient Descent Optimization for Low Power Nano-CMOS

    E-print Network

    Mohanty, Saraju P.

    Contributions Design flow methodology incorporating SGD for nano-CMOS design optimization Modification of SGD the gradient descent approach SGD reiteratively steps through the gradient descent until it converges At each is randomly chosen ­ also referred as training set Modified SGD restarts at random points to mitigate local

  5. SGD-QN: Careful Quasi-Newton Stochastic Gradient Descent

    Microsoft Academic Search

    Antoine Bordes; Léon Bottou; Patrick Gallinari

    2009-01-01

    The SGD-QN algorithm is a stochastic gradient descent algorithm that makes careful use of second- order information and splits the parameter update into independently scheduled components. Thanks to this design, SGD-QN iterates nearly as fast as a first-order stochastic gradient descent but requires less iterations to achieve the same accuracy. This algorith m won the \\

  6. The ontogeny of associative cerebellar learning.

    PubMed

    Freeman, John H

    2014-01-01

    Ontogenetic changes in associative cerebellar learning have been examined extensively using eyeblink conditioning in infant humans and rats. The cerebellum is essential for eyeblink conditioning in adult and infant animals. The cerebellum receives input from the conditional stimulus (CS) through the pontine mossy fiber projection and unconditional stimulus (US) input through the inferior olive climbing fiber projection. Coactivation of the CS and US pathways induces synaptic plasticity in the cerebellum, which is necessary for the conditional response. Ontogenetic changes in eyeblink conditioning are driven by developmental changes in the projections of subcortical sensory nuclei to the pontine nuclei and in the inhibitory projection from the cerebellar deep nuclei to the inferior olive. Developmental changes in the CS and US pathways limit the induction of learning-related plasticity in the cerebellum and thereby limit acquisition of eyeblink conditioning. PMID:25172629

  7. Cerebellar Dysfunction in a Patient with HIV

    PubMed Central

    Abdul, Waheed; Eivaz-Mohammadi, Sahar; Gongireddy, Srinivas; Syed, Amer

    2014-01-01

    A 50-year-old AIDS patient with a CD4 T-cell count of 114/mm3 was admitted with cerebellar symptoms of left CN XI weakness, wide-based gait with left-sided dysmetria, abnormal heel-knee-shin test, and dysdiadochokinesia. MRI showed region of hyperintensity in the left inferior cerebellar hemisphere involving the cortex and underlying white matter. Serological tests for HSV1, HSV2, and syphilis were negative. Her CSF contained high protein content and a WBC of 71/mm3, predominantly lymphocytes. The CSF was also negative for cryptococcal antigen and VDRL. CSF culture did not grow microbes. CSF PCR assay was negative for HSV1 and HSV2 but was positive for JC virus (1,276 copies). The most likely diagnosis is granule cell neuronopathy (GCN), which can only be definitively confirmed with biopsy and immunohistochemistry. PMID:25093131

  8. Cerebellar Dysfunction in a Patient with HIV.

    PubMed

    Gonzalez-Ibarra, Fernando; Abdul, Waheed; Eivaz-Mohammadi, Sahar; Foscue, Christopher; Gongireddy, Srinivas; Syed, Amer

    2014-01-01

    A 50-year-old AIDS patient with a CD4 T-cell count of 114/mm(3) was admitted with cerebellar symptoms of left CN XI weakness, wide-based gait with left-sided dysmetria, abnormal heel-knee-shin test, and dysdiadochokinesia. MRI showed region of hyperintensity in the left inferior cerebellar hemisphere involving the cortex and underlying white matter. Serological tests for HSV1, HSV2, and syphilis were negative. Her CSF contained high protein content and a WBC of 71/mm(3), predominantly lymphocytes. The CSF was also negative for cryptococcal antigen and VDRL. CSF culture did not grow microbes. CSF PCR assay was negative for HSV1 and HSV2 but was positive for JC virus (1,276 copies). The most likely diagnosis is granule cell neuronopathy (GCN), which can only be definitively confirmed with biopsy and immunohistochemistry. PMID:25093131

  9. An update on Spino-cerebellar ataxias

    PubMed Central

    Mondal, Banashree; Paul, Pritikanta; Paul, Madhuparna; Kumar, Hrishikesh

    2013-01-01

    The dominantly inherited ataxias, also known as Spino-cerebellar ataxias (SCAs), are rapidly expanding entities. New mutations are being identified at remarkable regularity. Recent awareness of molecular abnormalities in SCAs has addressed some of the long sought questions, but gaps in knowledge still exist. Three major categories of SCAs, according to molecular mechanisms, have evolved over recent few years: Polyglutamate expansion ataxia, non-coding zone repeat ataxia, and ataxia due to conventional mutation. Using the fulcrum of these mechanisms, the article provides an update of SCAs. Shared and specific clinical features, genetic abnormalities, and possible links between molecular abnormalities and cerebellar degeneration have been discussed. Emphasis has been placed on the mechanisms of polyglutamate toxicity. PMID:24101804

  10. Paraneoplastic cerebellar degeneration heralding fallopian tube adenocarcinoma.

    PubMed

    Levite, R; Fishman, A; Kesler, A; Altaras, M; Gadoth, N

    2001-01-01

    The objective of this paper is to describe an 81-year-old woman with subacute cerebellar degeneration due to fallopian tube adenocarcinoma. Serum anti-Yo antibodies were used to screen for pelvic malignancy. Their presence led to a meticulous search, which included bilateral salpingoophorectomy. Subsequently an occult fallopian tube adenocarcinoma was discovered. This case report highlights the diagnostic value of antineuroneal antibodies in females with subacute neurologic impairment in the form of paraneoplastic syndrome. PMID:11328418

  11. Cerebellar hallmarks of conditioned preference for cocaine.

    PubMed

    Carbo-Gas, Maria; Vazquez-Sanroman, Dolores; Gil-Miravet, Isis; De las Heras-Chanes, Joan; Coria-Avila, Genaro A; Manzo, Jorge; Sanchis-Segura, Carla; Miquel, Marta

    2014-06-10

    Pavlovian conditioning tunes the motivational drive of drug-associated stimuli, fostering the probability of those environmental stimuli to promote and trigger drug seeking and taking. Interestingly, different areas in the cerebellum are involved in the formation and long-lasting storage of Pavlovian emotional memory. Very recently, we have shown that conditioned preference for an odour associated with cocaine was directly correlated with cFOS expression in cells at the dorsal region of the granule cell layer of the cerebellar vermis. The main goal of the current investigation was to further extend the description of cFOS-IR patterns in cerebellar circuitry after training mice in a cocaine-odour Pavlovian conditioning procedure, including now the major inputs (the inferior olive and pontine nuclei) and one of the output nuclei (the medial deep nucleus) of the cerebellum. The results showed that the cerebellar hallmark of preference towards an odour cue associated to cocaine is an increase in cFOS expression in the dorsal part of the granule cell layer. cFOS-IR levels expressed in the granule cell layer of mice that did not show cocaine conditioned preference did not differ from the basal levels. Remarkably, mice subjected to a random cocaine-odour pairing procedure (the unpaired group) exhibited higher cFOS-IR in the inferior olive, the pontine nuclei and in the deep medial nucleus. Therefore, our findings suggest that inputs and the output of cerebellar circuitry are enhanced when contingency between the CS+ and cocaine is lacking. PMID:24813699

  12. Cerebellar Dermoid Cyst with Occipital Dermal Sinus

    Microsoft Academic Search

    F. Layadi; N. Louhab; M. Lmejjati; K. Aniba; A. Aďt Elqadi; S. Aďt Benali

    2006-01-01

    Intracranial dermoid cyst is a rare entity accounting for 0.1–0.7% of all intracranial tumors. The most common location is in the posterior fossa, at or near the midline. We present 2 pediatric cases with dermal sinus. The first case presented with clinical signs of increased intracranial pressure and cerebellar symptoms. CT scan showed a large and regular midline posterior fossa

  13. Moving, sensing and learning with cerebellar damage

    PubMed Central

    Bastian, Amy J

    2011-01-01

    The cerebellum is a subcortical brain structure that is essential for learning and controlling movement. Recent work shows that the cerebellum also plays a role in certain perceptual abilities, beyond what would be expected secondary to poor movement control. This review covers these and other recent advances, focusing on how cerebellar damage affects human abilities ranging from sensory perception to movement control and motor learning. PMID:21733673

  14. Cerebellar Disorders in Childhood: Cognitive Problems

    Microsoft Academic Search

    Maja Steinlin

    2008-01-01

    Over the last decade, increasing evidence of cognitive functions of the cerebellum during development and learning processes\\u000a could be ascertained. Posterior fossa malformations such as cerebellar hypoplasia or Joubert syndrome are known to be related\\u000a to developmental problems in a marked to moderate extent. More detailed analyses reveal special deficits in attention, processing\\u000a speed, visuospatial functions, and language. A study

  15. Cerebellar dysregulation and heterogeneity of mood disorders

    PubMed Central

    Tobe, Edward H

    2014-01-01

    This paper discusses diverse studies to consider the hypothesis that cerebellar pathology supports the heterogeneous metabolic pathologies of mood disorders. The evidence presented includes studies selected from the following areas of scientific research: magnetic resonance imaging, histology, clinical syndromes, comparative anatomy, neuronal connections, and mitochondrial dysfunction. The gamut of different scientific study methods confirms the validity of the involvement of the cerebellum in mood disorders. PMID:25092983

  16. Sporadic cerebellar ataxia associated with gluten sensitivity.

    PubMed

    Bürk, K; Bösch, S; Müller, C A; Melms, A; Zühlke, C; Stern, M; Besenthal, I; Skalej, M; Ruck, P; Ferber, S; Klockgether, T; Dichgans, J

    2001-05-01

    A total of 104 patients with sporadic cerebellar ataxia were tested for antigliadin and antiendomysium antibodies. Twelve individuals (11.5%) with gluten sensitivity underwent duodenal biopsy and extensive clinical, electrophysiological, neuropsychological, radiological and laboratory investigations including human leucocyte antigen (HLA) typing. Two patients showed typical changes of gluten-sensitive enteropathy with crypt hyperplasia and mucosal flattening. In five patients, the intraepithelial lymphocyte count was elevated. Sporadic ataxia with gluten sensitivity was found to be tightly linked to the HLA DQB1*0201 haplotype (70%). Neurological symptoms were not related to hypovitaminosis or inflammatory CSF changes. The clinical syndrome was dominated by progressive cerebellar ataxia with ataxia of stance and gait (100%), dysarthria (100%) and limb ataxia (97%). Oculomotor abnormalities were gaze-evoked nystagmus (66.7%), spontaneous nystagmus (33.3%), saccade slowing (25%) and upward gaze palsy (16.7%). Extracerebellar features also included deep sensory loss (58.3%), bladder dysfunction (33.3%) and reduced ankle reflexes (33.3%). In accordance with clinical findings, electrophysiological investigations revealed prominent axonal neuropathy with reduced amplitudes (50%) and abnormal evoked potentials (58.3%). On neuropsychological testing, patients presented with moderate verbal memory and executive dysfunction. All patients had evidence of cerebellar atrophy on MRI. We conclude that sporadic ataxia may be associated with positive antibodies against gliadin. Nevertheless, mucosal pathology does not represent an obligatory condition of ataxia with gluten sensitivity. The fact that the disease is strongly associated with the same HLA haplotypes found in coeliac disease not only demonstrates coeliac disease and ataxia with gluten sensitivity to be part of the same disease entity but supports the hypothesis of an immunological pathogenesis of cerebellar degeneration. PMID:11335703

  17. Oculomotor abnormalities parallel cerebellar histopathology in autism

    PubMed Central

    Takarae, Y; Minshew, N; Luna, B; Sweeney, J

    2004-01-01

    Methods: A visually guided saccade task was performed by 46 high-functioning individuals with autism with and without delayed language acquisition, and 104 age and IQ matched healthy individuals. Results: Individuals with autism had increased variability in saccade accuracy, and only those without delayed language development showed a mild saccadic hypometria. Neither autistic group showed a disturbance in peak saccade velocity or latency. Conclusions: The observed saccadic abnormalities suggest a functional disturbance in the cerebellar vermis or its output through the fastigial nuclei, consistent with reported cerebellar histopathology in autism. The pattern of mild hypometria and variable saccade accuracy is consistent with chronic rather than acute effects of cerebellar vermis lesions reported in clinical and non-human primate studies, as might be expected in a neurodevelopmental disorder. The different patterns of oculomotor deficits in individuals with autism with and without delayed language development suggest that pathophysiology at the level of the cerebellum may differ depending on an individual's history of language development. PMID:15314136

  18. Crossed cerebellar diaschisis accompanied by hemiataxia: a PET study.

    PubMed Central

    Tanaka, M; Kondo, S; Hirai, S; Ishiguro, K; Ishihara, T; Morimatsu, M

    1992-01-01

    To study crossed cerebellar diaschisis (CCD), cerebellar blood flow and oxygen metabolism were measured with positron emission tomography (PET) in 12 patients who showed a minimal degree of hemiparesis due to single unilateral supratentorial lesion. Six patients presenting with mild to moderate cerebellar type hemiataxia showed CCD, that is, decreased blood flow and oxygen metabolism in the cerebellar hemisphere contralateral to the side of supratentorial lesion. Hemiataxia and reduced cerebellar blood flow and metabolism occurred in the ipsilateral side. Lesions were located in the thalamus in four patients and the parietal lobe and internal capsule in one each. The other six patients did not exhibit ataxia, and oxygen metabolism was not reduced in the contralateral cerebellar hemisphere. In two of these cases, however, reduced cerebellar perfusion was observed in the contralateral cerebellar hemisphere. These findings indicate that CCD occurs with hemiataxia and suggest that it results not only from disruption of the corticopontocerebellar pathway but also of the dentatorubrothalamic pathway. CCD associated with hemiataxia, demonstrated in patients with thalamic lesions, was presumed to result from retrograde deactivation of the cerebellar hemisphere via the dentatorubrothalamic pathway. Images PMID:1538216

  19. Microglial activation underlies cerebellar deficits produced by repeated cannabis exposure

    PubMed Central

    Cutando, Laura; Busquets-Garcia, Arnau; Puighermanal, Emma; Gomis-González, Maria; Delgado-García, José María; Gruart, Agnčs; Maldonado, Rafael; Ozaita, Andrés

    2013-01-01

    Chronic cannabis exposure can lead to cerebellar dysfunction in humans, but the neurobiological mechanisms involved remain incompletely understood. Here, we found that in mice, subchronic administration of the psychoactive component of cannabis, delta9-tetrahydrocannabinol (THC), activated cerebellar microglia and increased the expression of neuroinflammatory markers, including IL-1?. This neuroinflammatory phenotype correlated with deficits in cerebellar conditioned learning and fine motor coordination. The neuroinflammatory phenotype was readily detectable in the cerebellum of mice with global loss of the CB1 cannabinoid receptor (CB1R, Cb1–/– mice) and in mice lacking CB1R in the cerebellar parallel fibers, suggesting that CB1R downregulation in the cerebellar molecular layer plays a key role in THC-induced cerebellar deficits. Expression of CB2 cannabinoid receptor (CB2R) and Il1b mRNA was increased under neuroinflammatory conditions in activated CD11b-positive microglial cells. Furthermore, administration of the immunosuppressant minocycline or an inhibitor of IL-1? receptor signaling prevented the deficits in cerebellar function in Cb1–/– and THC-withdrawn mice. Our results suggest that cerebellar microglial activation plays a crucial role in the cerebellar deficits induced by repeated cannabis exposure. PMID:23934130

  20. Bridle Device in Mars Science Laboratory Descent Stage

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This view of a portion of the descent stage of NASA's Mars Science Laboratory shows two of the stage's three spherical fuel tanks flanking the bridle device assembly. The photograph was taken in early October 2008 from the center of the descent stage looking outward. The top of the descent stage is toward the top of the image.

    The bridle device assembly is about two-thirds of a meter, or 2 feet, from top to bottom, and has two main parts. The cylinder on the top is the descent brake. The conical-shaped mechanism below that is the bridle assembly, including a spool of nylon and Vectran cords that will be attached to the rover.

    When pyrotechnic bolts fire to sever the rigid connection between the rover and the descent stage, gravity will pull the tethered rover away from the descent stage. The bridle or tether, attached to three points on the rover, will unspool from the bridle assembly, beginning from the larger-diameter portion. The rotation rate of the assembly, hence the descent rate of the rover, will be governed by the descent brake. Inside the housing of that brake are gear boxes and banks of mechanical resistors engineered to prevent the bridle from spooling out too quickly or too slowly. The length of the bridle will allow the rover to be lowered about 7.5 meters (25 feet) while still tethered to the descent stage.

    The Starsys division of SpaceDev Inc., Poway, Calif., provided the descent brake. NASA's Jet Propulsion Laboratory, Pasadena, Calif., built the bridle assembly. Vectran is a product of Kuraray Co. Ltd., Tokyo. JPL, a division of the California Institute of Technology, manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington.

  1. Distributed Control by Lagrangian Steepest Descent

    NASA Technical Reports Server (NTRS)

    Wolpert, David H.; Bieniawski, Stefan

    2004-01-01

    Often adaptive, distributed control can be viewed as an iterated game between independent players. The coupling between the players mixed strategies, arising as the system evolves from one instant to the next, is determined by the system designer. Information theory tells us that the most likely joint strategy of the players, given a value of the expectation of the overall control objective function, is the minimizer of a function o the joint strategy. So the goal of the system designer is to speed evolution of the joint strategy to that Lagrangian mhimbhgpoint,lowerthe expectated value of the control objective function, and repeat Here we elaborate the theory of algorithms that do this using local descent procedures, and that thereby achieve efficient, adaptive, distributed control.

  2. Error analysis of stochastic gradient descent ranking.

    PubMed

    Chen, Hong; Tang, Yi; Li, Luoqing; Yuan, Yuan; Li, Xuelong; Tang, Yuanyan

    2013-06-01

    Ranking is always an important task in machine learning and information retrieval, e.g., collaborative filtering, recommender systems, drug discovery, etc. A kernel-based stochastic gradient descent algorithm with the least squares loss is proposed for ranking in this paper. The implementation of this algorithm is simple, and an expression of the solution is derived via a sampling operator and an integral operator. An explicit convergence rate for leaning a ranking function is given in terms of the suitable choices of the step size and the regularization parameter. The analysis technique used here is capacity independent and is novel in error analysis of ranking learning. Experimental results on real-world data have shown the effectiveness of the proposed algorithm in ranking tasks, which verifies the theoretical analysis in ranking error. PMID:24083315

  3. Error Analysis of Stochastic Gradient Descent Ranking.

    PubMed

    Chen, Hong; Tang, Yi; Li, Luoqing; Yuan, Yuan; Li, Xuelong; Tang, Yuanyan

    2012-12-31

    Ranking is always an important task in machine learning and information retrieval, e.g., collaborative filtering, recommender systems, drug discovery, etc. A kernel-based stochastic gradient descent algorithm with the least squares loss is proposed for ranking in this paper. The implementation of this algorithm is simple, and an expression of the solution is derived via a sampling operator and an integral operator. An explicit convergence rate for leaning a ranking function is given in terms of the suitable choices of the step size and the regularization parameter. The analysis technique used here is capacity independent and is novel in error analysis of ranking learning. Experimental results on real-world data have shown the effectiveness of the proposed algorithm in ranking tasks, which verifies the theoretical analysis in ranking error. PMID:23292808

  4. Investigating Common Descent: Formulating Explanations and Models

    NSDL National Science Digital Library

    This activity has students formulate explanations and models that simulate structural and biochemical data as they investigate the misconception that humans evolved from apes. Students should recognize that present-day species evolved from earlier species and the relatedness of organisms is the result of common ancestry. They will also discover that similarities among existing organisms provide evidence for evolution, anatomical similarities of living things reflect common ancestry, and all life forms use the same basic DNA building blocks. Basic concepts also include the fact that scientists pose, test, and revise multiple hypotheses to explain what they observe, our understanding of life through time is based upon multiple lines of evidence, the similarity of DNA nucleotide sequences can be used to infer the degree of kinship between species, and anatomical evidence is also used to infer lines of descent. This site includes a list of materials and all information required for this activity.

  5. Simulator Evaluation of a New Cockpit Descent Procedure

    NASA Technical Reports Server (NTRS)

    Crane, Barry; Palmer, Everett; Smith, Nancy; Rosekind, Mark (Technical Monitor)

    1996-01-01

    An experiment was conducted to evaluate flight crew performance of the "Precision Descent," a new cockpit procedure designed to support the Descent Advisor (DA), one of the components in a new air traffic control advisory system called the "Center-TRACON Automation System" (CTAS). The DA predicts when aircraft will reach a specific waypoint on the arrival route, and presents controllers with clearance advisories designed to improve the sequencing of arriving aircraft. The effectiveness of the DA depends on the aircraft's descent trajectory: where it begins descent, what speed it maintains, how fast and at what altitude it crosses the bottom-of-descent waypoint. The Precision Descent allows controllers to assign these descent parameters to the flight crew. A Field Evaluation of the DA was conducted in Denver in 1995. Three separate clearances using standard ATC phraseology were used to support the cockpit descent procedure during this evaluation. The number and length of these clearances caused problems for both controllers and flight crews, causing readback errors, repeat requests and procedure misunderstandings. These observations led to a focus group meeting in which controller and pilot participants in the 1995 FE assisted in the redesign of the procedure. The Precision Descent eliminates one clearance used in the earlier study, and greatly reduces the length of the remaining clearances. This was accomplished by using non-standard clearance phraseology that relies on a published procedure chart for correct interpretation. Eight type-rated flight crews flew eight Precision Descents in a Boeing 747-400 simulator. No training was provided: crews received either a procedure chart or a procedure chart with a flight manual bulletin describing procedure techniques. Video and digital data were recorded for each descent. Preliminary results indicate that moving information from the verbal clearance to the chart was successful: the shorter clearances and the procedure's default crossing restriction were understood, and procedure compliance of 81% was observed across all descents on six independent compliance measures. Some readback errors and procedure misunderstandings were still observed, however; particularly when descent clearances deviated from the normative procedure.

  6. Onset and Distribution of Tissue PrP Accumulation in Scrapie-affected Suffolk Sheep as Demonstrated by Sequential Necropsies and Tonsillar Biopsies

    Microsoft Academic Search

    M. Jeffrey; S. Martin; J. R. Thomson; W. S. Dingwall; I. Begara-McGorum; L. González

    2001-01-01

    Tonsillar biopsies (single or multiple) or necropsies, or both, were performed on sheep taken from a Suffolk flock in which frequent cases of scrapie had occurred over a period of several years. Clinically affected sheep of the susceptible PrPAQ\\/AQgenotype had widespread disease-specific PrP accumulation in the central nervous system (CNS), lymphoreticular system and peripheral ganglia. In nine healthy PrPAQ\\/AQSuffolk sheep

  7. Evaluation of Cerebellar Size in Attention-Deficit Hyperactivity Disorder

    Microsoft Academic Search

    Stewart H. Mostofsky; Allan L. Reiss; Paula Lockhart; Martha Bridge Denckla

    1998-01-01

    Evidence from animal and human research suggests that the cerebellum may play a role in cognition. This includes domains of executive function that are normally attributed to the prefrontal cortex and are typically deficient in individuals with attention-deficit hyperactivity disorder (ADHD). To investigate cerebellar structure in ADHD, magnetic resonance imaging morphometry was used to measure the area of the cerebellar

  8. Increased cerebellar volume and BDNF level following quadrato motor training.

    PubMed

    Ben-Soussan, Tal Dotan; Piervincenzi, Claudia; Venditti, Sabrina; Verdone, Loredana; Caserta, Micaela; Carducci, Filippo

    2015-01-01

    Using whole-brain structural measures coupled to analysis of salivary brain-derived neurotrophic factor (BDNF), we demonstrate sensory motor training-induced plasticity, including cerebellar gray matter volume increment and increased BDNF level. The increase of cerebellar volume was positively correlated with the increase of BDNF level. PMID:25311848

  9. Distinct Critical Cerebellar Subregions for Components of Verbal Working Memory

    ERIC Educational Resources Information Center

    Cooper, Freya E.; Grube, Manon; Von Kriegstein, Katharina; Kumar, Sukhbinder; English, Philip; Kelly, Thomas P.; Chinnery, Patrick F.; Griffiths, Timothy D.

    2012-01-01

    A role for the cerebellum in cognition has been proposed based on studies suggesting a profile of cognitive deficits due to cerebellar stroke. Such studies are limited in the determination of the detailed organisation of cerebellar subregions that are critical for different aspects of cognition. In this study we examined the correlation between…

  10. [Clinical study of two cases of traumatic cerebellar injury].

    PubMed

    Yokota, H; Nakazawa, S; Kobayashi, S; Taniguchi, Y; Yukihide, T

    1990-01-01

    Two cases of traumatic cerebellar injury complicated with a traumatic medial longitudinal fasciculus (MLF) syndrome or cerebellar mutism were reported, and the cause of these mechanisms was discussed: Case 1: A 9-year-old boy who struck his head in the occipital region during an automobile accident was operated on for a delayed traumatic intracerebellar hematoma. The operation improved the level of his consciousness but MLF syndrome was noticed. The mechanism of traumatic MLF syndrome was discussed in relation to vascular injury and to neurovascular friction. The outcome of the syndrome including our case, which recovered spontaneously, seemed to support the theory of neurovascular injury. Case 2: A 6-year-old boy who struck his head in the temporooccipital region during an automobile accident was admitted to our hospital without conciousness. On admission, contusion of the temporal lobe and left cerebellar hemisphere was demonstrated by a computerized tomography (CT) and magnetic resonance imaging (MRI). A mute state (cerebellar mutism) was recognized after his recovery of consciousness. The cause of the cerebellar mutism was thought to be an injury of the cerebellar vermis or left cerebellar hemisphere. The findings of CT scan and MRI in our case suggested that the cause of the cerebellar mutism was the contusion of these areas. PMID:2406638

  11. Cerebellar neurocognition: insights into the bottom of the brain.

    PubMed

    Baillieux, Hanne; De Smet, Hyo Jung; Paquier, Philippe F; De Deyn, Peter P; Mariën, Peter

    2008-09-01

    The traditional view on the core functions of the cerebellum consists of the regulation of motor coordination, balance and motor speech. However, during the past decades results from neuroanatomical, neuroimaging and clinical studies have substantially extended the functional role of the cerebellum to cognitive and affective regulation. Neuroanatomical studies convincingly showed cerebellar connectivity with associative areas of the cerebral cortex involved in higher cognitive functioning, while functional neuroimaging provided evidence of cerebellar activation during a variety of cognitive tasks. In addition, more systematic neuropsychological research performed in patients with cerebellar lesions and the development of more sensitive neuropsychological tests allowed clinicians to identify significant cognitive and affective disturbances following cerebellar damage. In this review, an overview is presented of the cerebellar role in a variety of cognitive processes, such as executive functioning, memory, learning, attention, visuo-spatial regulation, language and behavioral-affective modulation. In addition, recent evidence with regard to cerebellar induced clinical entities such as the cerebellar cognitive affective syndrome (CCAS) and the posterior fossa syndrome (PFS), will be discussed. Although extensive research has substantially broadened the insights in the cognitive and affective role of the cerebellum, the precise nature of the cerebellar contribution to cognitive and affective regulation is not yet clear. In this review experimental and clinical data will be discussed that substantiate the presumed neurobiological mechanisms underlying the cognitive and affective modulatory role of the cerebellum. PMID:18602745

  12. Original Research Cerebellar Transcranial Magnetic Stimulation: The Role of Coil

    E-print Network

    Miall, Chris

    Keywords: Cerebellum TMS Cerebello brain inhibition Cerebellar brain inhibition TMS coil geometry Deep TMS magnetic stimulation (TMS) coil geometry has important effects on the evoked magnetic field, no study has cerebellar TMS studies. Ă? 2014 Elsevier Inc. All rights reserved. Introduction Transcranial magnetic

  13. Cerebellar theta burst stimulation in stroke patients with ataxia

    PubMed Central

    Bonně, Sonia; Ponzo, Viviana; Caltagirone, Carlo; Koch, Giacomo

    2014-01-01

    Summary Evidence for effective improvement of the symptoms of cerebellar stroke is still limited. Here, we investigated the effects of repetitive transcranial magnetic stimulation (rTMS) applied over the injured cerebellar hemisphere in six patients with posterior circulation stroke. We applied a two-week course of cerebellar intermittent theta burst stimulation (iTBS). Before and after the iTBS treatment, paired-pulse TMS methods were used to explore: i) the functional connectivity between the cerebellar hemisphere and the contralateral primary motor cortex (M1), by means of the cerebellar brain inhibition (CBI) protocol; and ii) the intracortical circuits in the contralateral M1, by means of the short intra-cortical inhibition (SICI) and intra-cortical facilitation (ICF) protocols. Patients were also evaluated using the Modified International Cooperative Ataxia Rating Scale (MICARS). Cerebellar iTBS induced a decrease in CBI and an increase in ICF at an interstimulus interval of 15 msec. These neurophysiological changes were paralleled by a clinical improvement, shown by the MICARS posture and gait subscale scores. Cerebellar iTBS could be a promising tool to promote recovery of cerebellar stroke patients. PMID:25014048

  14. CASE REPORT Open Access Autosomal recessive cerebellar ataxia caused

    E-print Network

    Paris-Sud XI, Université de

    CASE REPORT Open Access Autosomal recessive cerebellar ataxia caused by mutations in the PEX2 gene Objective: To expand the spectrum of genetic causes of autosomal recessive cerebellar ataxia (ARCA). Case strongly suggested a peroxisomal biogenesis disorder. Sequencing of candidate PEX genes revealed

  15. Intra-iteration Approximation for Large Scale Parallel Gradient Descent Optimization Chengjie Qin & Florin Rusu

    E-print Network

    Rusu, Florin

    and to allow interactive parameter tuning. (Stochastic) Gradient Descent Problem definition: minwRd (w) def = N Gradient Descent w(k+1) = w(k) - (k) w(k) Stochastic Gradient Descent w(k+1) = w(k) - (k) fi w(k) Datasets-iteration Approximation Parallel (Stochastic) Gradient Descent in GLADE #12; #12; #12; #12

  16. Automation for Accommodating Fuel-Efficient Descents in Constrained Airspace

    NASA Technical Reports Server (NTRS)

    Coopenbarger, Richard A.

    2010-01-01

    Continuous descents at low engine power are desired to reduce fuel consumption, emissions and noise during arrival operations. The challenge is to allow airplanes to fly these types of efficient descents without interruption during busy traffic conditions. During busy conditions today, airplanes are commonly forced to fly inefficient, step-down descents as airtraffic controllers work to ensure separation and maximize throughput. NASA in collaboration with government and industry partners is developing new automation to help controllers accommodate continuous descents in the presence of complex traffic and airspace constraints. This automation relies on accurate trajectory predictions to compute strategic maneuver advisories. The talk will describe the concept behind this new automation and provide an overview of the simulations and flight testing used to develop and refine its underlying technology.

  17. 14 CFR 31.19 - Performance: Uncontrolled descent.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...be determined for the most critical uncontrolled descent that can result from any single failure of the heater assembly, fuel cell system, gas value system, or maneuvering vent system, or from any single tear in the balloon envelope between...

  18. TextBased Information Retrieval Using Exponentiated Gradient Descent

    E-print Network

    Callan, Jamie

    Text­Based Information Retrieval Using Exponentiated Gradient Descent Ron Papka, James P. Callan papka@cs.umass.edu, callan@cs.umass.edu, barto@cs.umass.edu Abstract The following investigates the use

  19. Ascent/descent ancillary data production user's guide

    NASA Technical Reports Server (NTRS)

    Brans, H. R.; Seacord, A. W., II; Ulmer, J. W.

    1986-01-01

    The Ascent/Descent Ancillary Data Product, also called the A/D BET because it contains a Best Estimate of the Trajectory (BET), is a collection of trajectory, attitude, and atmospheric related parameters computed for the ascent and descent phases of each Shuttle Mission. These computations are executed shortly after the event in a post-flight environment. A collection of several routines including some stand-alone routines constitute what is called the Ascent/Descent Ancillary Data Production Program. A User's Guide for that program is given. It is intended to provide the reader with all the information necessary to generate an Ascent or a Descent Ancillary Data Product. It includes descriptions of the input data and output data for each routine, and contains explicit instructions on how to run each routine. A description of the final output product is given.

  20. Efficient coordinate descent for ranking with domination loss

    E-print Network

    Stevens, Mark A., M. Eng. Massachusetts Institute of Technology

    2010-01-01

    We define a new batch coordinate-descent ranking algorithm based on a domination loss, which is designed to rank a small number of positive examples above all negatives, with a large penalty on false positives. Its objective ...

  1. Randomized coordinate descent methods for big data optimization 

    E-print Network

    Takac, Martin

    2014-07-01

    This thesis consists of 5 chapters. We develop new serial (Chapter 2), parallel (Chapter 3), distributed (Chapter 4) and primal-dual (Chapter 5) stochastic (randomized) coordinate descent methods, analyze their complexity ...

  2. Large-Scale Matrix Factorization with Distributed Stochastic Gradient Descent

    E-print Network

    . Our approach rests on stochastic gradient descent (SGD), an iterative stochastic optimization algorithm. We first develop a novel "stratified" SGD variant (SSGD) that applies to general loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2. SGD for Matrix Factorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4

  3. Fuel-Conservative Descents Using A Programable Calcultor

    NASA Technical Reports Server (NTRS)

    Knox, C. E.

    1985-01-01

    Airborne descent algorithm used with or without time constraints. Concepts provide fuel savings by matching airplane arrival flow to airport acceptance rate through time control computations and allowing pilot to descend at his descretion from cruise altitude to designated metering fix in idle-thrust clean (landing gear up, flaps, zero, and speed brakes retracted) configuration. Also used for planning fuel-conservative descents when time is not consideration.

  4. Fractional extreme value adaptive training method: fractional steepest descent approach.

    PubMed

    Pu, Yi-Fei; Zhou, Ji-Liu; Zhang, Yi; Zhang, Ni; Huang, Guo; Siarry, Patrick

    2015-04-01

    The application of fractional calculus to signal processing and adaptive learning is an emerging area of research. A novel fractional adaptive learning approach that utilizes fractional calculus is presented in this paper. In particular, a fractional steepest descent approach is proposed. A fractional quadratic energy norm is studied, and the stability and convergence of our proposed method are analyzed in detail. The fractional steepest descent approach is implemented numerically and its stability is analyzed experimentally. PMID:25314711

  5. Destruction of inferior olive induces rapid depression in synaptic action of cerebellar Purkinje cells

    Microsoft Academic Search

    Masao Ito; Naoko Nisimaru; Katsuei Shibuki

    1979-01-01

    THE climbing fibre afferents (CFAs) are a structure unique to the cerebellar cortex; they originate, presumably solely, from the inferior olive (IO) and make an extensive, excitatory synaptic contact with dendrites of cerebellar Purkinje cells (P cells)1. The importance of the CFAs in cerebellar functions has been emphasised in connection with the learning process which may occur in the cerebellar

  6. Orion Entry, Descent, and Landing Simulation

    NASA Technical Reports Server (NTRS)

    Hoelscher, Brian R.

    2007-01-01

    The Orion Entry, Descent, and Landing simulation was created over the past two years to serve as the primary Crew Exploration Vehicle guidance, navigation, and control (GN&C) design and analysis tool at the National Aeronautics and Space Administration (NASA). The Advanced NASA Technology Architecture for Exploration Studies (ANTARES) simulation is a six degree-of-freedom tool with a unique design architecture which has a high level of flexibility. This paper describes the decision history and motivations that guided the creation of this simulation tool. The capabilities of the models within ANTARES are presented in detail. Special attention is given to features of the highly flexible GN&C architecture and the details of the implemented GN&C algorithms. ANTARES provides a foundation simulation for the Orion Project that has already been successfully used for requirements analysis, system definition analysis, and preliminary GN&C design analysis. ANTARES will find useful application in engineering analysis, mission operations, crew training, avionics-in-the-loop testing, etc. This paper focuses on the entry simulation aspect of ANTARES, which is part of a bigger simulation package supporting the entire mission profile of the Orion vehicle. The unique aspects of entry GN&C design are covered, including how the simulation is being used for Monte Carlo dispersion analysis and for support of linear stability analysis. Sample simulation output from ANTARES is presented in an appendix.

  7. Tonsillar homing of Epstein-Barr virus–specific CD8+ T cells and the virus-host balance

    PubMed Central

    Hislop, Andrew D.; Kuo, Michael; Drake-Lee, Adrian B.; Akbar, Arne N.; Bergler, Wolfgang; Hammerschmitt, Nicolas; Khan, Naeem; Palendira, Umaimainthan; Leese, Alison M.; Timms, Judith M.; Bell, Andrew I.; Buckley, Christopher D.; Rickinson, Alan B.

    2005-01-01

    Patients with infectious mononucleosis (IM) undergoing primary EBV infection show large expansions of EBV-specific CD8+ T cells in the blood. While latent infection of the B cell pool is quickly controlled, virus shedding from lytically infected cells in the oropharynx remains high for several months. We therefore studied how responses localize to the tonsil, a major target site for EBV, during primary infection and persistence. In acute IM, EBV-specific effectors were poorly represented among CD8+ T cells in tonsil compared with blood, coincident with absence of the CCR7 lymphoid homing marker on these highly activated cells. In patients who had recently recovered from IM, latent epitope reactivities were quicker than lytic reactivities both to acquire CCR7 and to accumulate in the tonsil, with some of these cells now expressing the CD103 integrin, which mediates retention at mucosal sites. By contrast, in long-term virus carriers in whom both lytic and latent infections had been controlled, there was 2- to 5-fold enrichment of lytic epitope reactivities and 10- to 20-fold enrichment of latent epitope reactivities in tonsil compared with blood; up to 20% of tonsillar CD8+ T cells were EBV specific, and many now expressed CD103. We suggest that efficient control of EBV infection requires appropriate CD8+ T cell homing to oropharyngeal sites. PMID:16110323

  8. Contribution of Cerebellar Sensorimotor Adaptation to Hippocampal Spatial Memory

    PubMed Central

    Passot, Jean-Baptiste; Sheynikhovich, Denis; Duvelle, Éléonore; Arleo, Angelo

    2012-01-01

    Complementing its primary role in motor control, cerebellar learning has also a bottom-up influence on cognitive functions, where high-level representations build up from elementary sensorimotor memories. In this paper we examine the cerebellar contribution to both procedural and declarative components of spatial cognition. To do so, we model a functional interplay between the cerebellum and the hippocampal formation during goal-oriented navigation. We reinterpret and complete existing genetic behavioural observations by means of quantitative accounts that cross-link synaptic plasticity mechanisms, single cell and population coding properties, and behavioural responses. In contrast to earlier hypotheses positing only a purely procedural impact of cerebellar adaptation deficits, our results suggest a cerebellar involvement in high-level aspects of behaviour. In particular, we propose that cerebellar learning mechanisms may influence hippocampal place fields, by contributing to the path integration process. Our simulations predict differences in place-cell discharge properties between normal mice and L7-PKCI mutant mice lacking long-term depression at cerebellar parallel fibre-Purkinje cell synapses. On the behavioural level, these results suggest that, by influencing the accuracy of hippocampal spatial codes, cerebellar deficits may impact the exploration-exploitation balance during spatial navigation. PMID:22485133

  9. Abnormal cerebellar morphometry in abstinent adolescent marijuana users

    PubMed Central

    Medina, Krista Lisdahl; Nagel, Bonnie J.; Tapert, Susan F.

    2010-01-01

    Background Functional neuroimaging data from adults have, in general, found frontocerebellar dysfunction associated with acute and chronic marijuana (MJ) use (Loeber & Yurgelun-Todd, 1999). One structural neuroimaging study found reduced cerebellar vermis volume in young adult MJ users with a history of heavy polysubstance use (Aasly et al., 1993). The goal of this study was to characterize cerebellar volume in adolescent chronic MJ users following one month of monitored abstinence. Method Participants were MJ users (n=16) and controls (n=16) aged 16-18 years. Extensive exclusionary criteria included history of psychiatric or neurologic disorders. Drug use history, neuropsychological data, and structural brain scans were collected after 28 days of monitored abstinence. Trained research staff defined cerebellar volumes (including three cerebellar vermis lobes and both cerebellar hemispheres) on high-resolution T1-weighted magnetic resonance images. Results Adolescent MJ users demonstrated significantly larger inferior posterior (lobules VIII-X) vermis volume (p<.009) than controls, above and beyond effects of lifetime alcohol and other drug use, gender, and intracranial volume. Larger vermis volumes were associated with poorer executive functioning (p’s<.05). Conclusions Following one month of abstinence, adolescent MJ users had significantly larger posterior cerebellar vermis volumes than non-using controls. These greater volumes are suggested to be pathological based on linkage to poorer executive functioning. Longitudinal studies are needed to examine typical cerebellar development during adolescence and the influence of marijuana use. PMID:20413277

  10. Cerebellar Transcranial Direct Current Stimulation Effects on Saccade Adaptation

    PubMed Central

    van der Geest, Jos N.; Kengne Kamga, Sandra; Verhage, M. Claire; Donchin, Opher; Frens, Maarten A.

    2015-01-01

    Saccade adaptation is a cerebellar-mediated type of motor learning in which the oculomotor system is exposed to repetitive errors. Different types of saccade adaptations are thought to involve distinct underlying cerebellar mechanisms. Transcranial direct current stimulation (tDCS) induces changes in neuronal excitability in a polarity-specific manner and offers a modulatory, noninvasive, functional insight into the learning aspects of different brain regions. We aimed to modulate the cerebellar influence on saccade gains during adaptation using tDCS. Subjects performed an inward (n = 10) or outward (n = 10) saccade adaptation experiment (25% intrasaccadic target step) while receiving 1.5?mA of anodal cerebellar tDCS delivered by a small contact electrode. Compared to sham stimulation, tDCS increased learning of saccadic inward adaptation but did not affect learning of outward adaptation. This may imply that plasticity mechanisms in the cerebellum are different between inward and outward adaptation. TDCS could have influenced specific cerebellar areas that contribute to inward but not outward adaptation. We conclude that tDCS can be used as a neuromodulatory technique to alter cerebellar oculomotor output, arguably by engaging wider cerebellar areas and increasing the available resources for learning. PMID:25821604

  11. Heat stroke induced cerebellar dysfunction: A "forgotten syndrome".

    PubMed

    Kosgallana, Athula D; Mallik, Shreyashee; Patel, Vishal; Beran, Roy G

    2013-11-16

    We report a case of heat stroke induced acute cerebellar dysfunction, a rare neurological disease characterized by gross cerebellar dysfunction with no acute radiographic changes, in a 61 years old ship captain presenting with slurred speech and gait ataxia. A systematic review of the literature on heat stroke induced cerebellar dysfunction was performed, with a focus on investigations, treatment and outcomes. After review of the literature and detailed patient investigation it was concluded that this patient suffered heat stroke at a temperature less than that quoted in the literature. PMID:24340279

  12. Cerebellar Mutism Following Closed Head Injury in a Child

    PubMed Central

    Kariyattil, Rajeev; Rahim, Mohamed I. A.; Muthukuttiparambil, Unnikrishnan

    2015-01-01

    Cerebellar mutism is a rare occurrence following paediatric trauma. Although it is quite common after posterior fossa surgery in children, this phenomenon has rarely been reported following other insults, such as trauma, and its pathophysiology remains poorly understood. We report a seven-year-old child who presented to the casualty department of Sultan Qaboos University Hospital in Muscat, Oman, in May 2013 with a traumatic right cerebellar contusion. The child presented with clinical features of cerebellar mutism but underwent a rapid and spontaneous recovery. The possible mechanism of this occurrence is discussed. PMID:25685374

  13. A descent of the aurora over Lapland

    NASA Astrophysics Data System (ADS)

    Whiter, Daniel; Partamies, Noora

    2014-05-01

    A very large statistical study (? 4 × 105 measurements) into the peak emission height of the aurora has shown that the aurora over Lapland descended significantly between 1996 and 2007. The study was performed using images from a network of ground-based all-sky cameras which form part of the MIRACLE (Magnetometers-Ionospheric Radar-All-sky Cameras Large Experiment) network, and are located at various observation stations across northern Finland and Sweden. The height of the aurora was first measured about a century ago. Since then, it has generally been assumed that the peak emission height of any particular auroral emission is constant for similar geomagnetic conditions. The present work was motivated by the need to improve estimates of the height of the aurora used to calculate other ionospheric and auroral properties, such as optical flow velocities and auroral arc widths. In recent years MIRACLE has produced approximately 105 images of the aurora per station per year. In order to analyse such a large number of images, a novel fast and automatic method was developed for finding the peak emission height of an auroral structure from a pair of all-sky camera images with overlapping fields of view. This method has been applied to all auroral images recorded by the MIRACLE intensified CCD cameras in operation between 1996 and 2007. Such a large data set allows the study of variations in the height of the aurora with time (yearly, monthly, hourly) and with solar and geomagnetic indices such as F10.7 and Kp. Results from the statistical study show that the peak emission height of green (557.7 nm, O1S - O1D transition) aurora over Lapland descended by about 10 km between 1996 and 2007. This descent occurred independently of the solar cycle, and is thought to be due to a cooling and contraction of the mesosphere and lower thermosphere.

  14. Design of automation tools for management of descent traffic

    NASA Technical Reports Server (NTRS)

    Erzberger, Heinz; Nedell, William

    1988-01-01

    The design of an automated air traffic control system based on a hierarchy of advisory tools for controllers is described. Compatibility of the tools with the human controller, a key objective of the design, is achieved by a judicious selection of tasks to be automated and careful attention to the design of the controller system interface. The design comprises three interconnected subsystems referred to as the Traffic Management Advisor, the Descent Advisor, and the Final Approach Spacing Tool. Each of these subsystems provides a collection of tools for specific controller positions and tasks. This paper focuses primarily on the Descent Advisor which provides automation tools for managing descent traffic. The algorithms, automation modes, and graphical interfaces incorporated in the design are described. Information generated by the Descent Advisor tools is integrated into a plan view traffic display consisting of a high-resolution color monitor. Estimated arrival times of aircraft are presented graphically on a time line, which is also used interactively in combination with a mouse input device to select and schedule arrival times. Other graphical markers indicate the location of the fuel-optimum top-of-descent point and the predicted separation distances of aircraft at a designated time-control point. Computer generated advisories provide speed and descent clearances which the controller can issue to aircraft to help them arrive at the feeder gate at the scheduled times or with specified separation distances. Two types of horizontal guidance modes, selectable by the controller, provide markers for managing the horizontal flightpaths of aircraft under various conditions. The entire system consisting of descent advisor algorithm, a library of aircraft performance models, national airspace system data bases, and interactive display software has been implemented on a workstation made by Sun Microsystems, Inc. It is planned to use this configuration in operational evaluations at an en route center.

  15. Mars Descent Imager (MARDI) on the Mars Polar Lander

    USGS Publications Warehouse

    Malin, M.C.; Caplinger, M.A.; Carr, M.H.; Squyres, S.; Thomas, P.; Veverka, J.

    2001-01-01

    The Mars Descent Imager, or MARDI, experiment on the Mars Polar Lander (MPL) consists of a camera characterized by small physical size and mass (???6 ?? 6 ?? 12 cm, including baffle; <500 gm), low power requirements (<2.5 W, including power supply losses), and high science performance (1000 x 1000 pixel, low noise). The intent of the investigation is to acquire nested images over a range of resolutions, from 8 m/pixel to better than 1 cm/pixel, during the roughly 2 min it takes the MPL to descend from 8 km to the surface under parachute and rocket-powered deceleration. Observational goals will include studies of (1) surface morphology (e.g., nature and distribution of landforms indicating past and present environmental processes); (2) local and regional geography (e.g., context for other lander instruments: precise location, detailed local relief); and (3) relationships to features seen in orbiter data. To accomplish these goals, MARDI will collect three types of images. Four small images (256 x 256 pixels) will be acquired on 0.5 s centers beginning 0.3 s before MPL's heatshield is jettisoned. Sixteen full-frame images (1024 X 1024, circularly edited) will be acquired on 5.3 s centers thereafter. Just after backshell jettison but prior to the start of powered descent, a "best final nonpowered descent image" will be acquired. Five seconds after the start of powered descent, the camera will begin acquiring images on 4 s centers. Storage for as many as ten 800 x 800 pixel images is available during terminal descent. A number of spacecraft factors are likely to impact the quality of MARDI images, including substantial motion blur resulting from large rates of attitude variation during parachute descent and substantial rocket-engine-induced vibration during powered descent. In addition, the mounting location of the camera places the exhaust plume of the hydrazine engines prominently in the field of view. Copyright 2001 by the American Geophysical Union.

  16. DNER as key molecule for cerebellar maturation.

    PubMed

    Saito, Shin-Ya; Takeshima, Hiroshi

    2006-01-01

    Notch signaling plays an important role in the process of cell-fate assignation during nervous system development. DNER is a neuron-specific transmembrane protein carrying extracellular EGF-like repeats and is expressed in somatodendritic regions. In vitro studies demonstrated that DNER mediates Notch signaling by cell-cell interaction. In the cerebellum, DNER is abundantly expressed in Purkinje cells and moderately in granule cells. DNER-knockout mice showed motor discoordination. The mutant cerebellum showed morphological impairments of Bergmann glia and multiple innervation between climbing fibers and Purkinje cells. Moreover, glutamate clearance at the synapses between parallel fibers and Purkinje cells was significantly weakened, and the expression of GLAST, a glutamate transporter in Bergmann glia, was reduced in the mutant cerebellum. Therefore, DNER contributes to the morphological and functional maturation of Bergmann glia via the Notch signaling pathway, and is essential for precise cerebellar development. PMID:16997755

  17. Planned gait termination in cerebellar ataxias.

    PubMed

    Conte, Carmela; Serrao, Mariano; Casali, Carlo; Ranavolo, Alberto; Silvia, Mari; Draicchio, Francesco; Di Fabio, Roberto; Monami, Stefano; Padua, Luca; Iavicoli, Sergio; Sandrini, Giorgio; Pierelli, Francesco

    2012-12-01

    This study set out to characterise the pattern of planned gait termination in a sample of patients with cerebellar diseases. The gait termination phase was recorded, using a motion analysis system, in ten patients with primary degenerative cerebellar disease and in ten controls. The subjects were instructed to walk at different gait speeds and to stop in response to an acoustic signal. Time-distance parameters (step length, step width, double support duration, time-to-slow, stopping time, centre of mass velocity and number of steps) and stability index-related parameters (distance between the "extrapolated centre of mass" (XCoM) and centre of pressure (CoP)) were measured at both matched and self-selected gait speeds. At matched speed the patients, compared with the controls, showed a reduced step length, a greater first and second step width and used more steps to stop. At self-selected speed, almost all the parameters differed from those of the controls. Furthermore, the patients showed an increased stability index, suggesting that they need to maintain a "safety margin" between the XCoM and CoP during the gait termination. Patients develop a series of compensatory strategies in order to preserve balance during planned gait termination, e.g. increasing their step width and number of steps. Ataxic patients need to maintain a safety margin in order to avoid instability when stopping. Given the potential risk of falls when stopping, walking ataxic patients may benefit from a rehabilitation treatment focused on preserving and improving their ability to terminate gait safely. PMID:22274811

  18. [Clinical investigation of cerebellar astrocytomas in childhood].

    PubMed

    Yasue, M; Tomita, T; McLone, D G

    1988-02-01

    Between 1970 and 1985, 58 children with pathologically proven cerebellar astrocytoma were treated at the Children's Memorial Hospital in Chicago. Histological distribution indicated 54 were Grade 1-2 and the remaining 4 patients had Grade 3 astrocytoma. Thirty-eight were evaluated by CT scans and classified into 3 groups, (1) cyst with mural nodule, (2) cyst within tumor and (3) solid type. All patients underwent a posterior fossa craniotomy and 2 cases (3.4%) died shortly after the operation. Forty-two patients underwent visible total resection and 16 subtotal or less resection. The recurrence rate in subtotal resection group (53.3%) is much higher than in total resection group (9.8%) (p less than 0.01) and the highest in solid type. Seven out of 8 cases who developed recurrence after subtotal removal were in the midline location, and 6 out of 7 cases who did not show any recurrence were cystic in nature. About two-thirds of patients had good outcome, 32% had fair and 4% had poor outcome. The hemispheric tumors led the patient to a better outcome but the midline solid tumors caused poor outcome. Fifty patients were diagnosed to have hydrocephalus preoperatively. Postoperative permanent hydrocephalus developed in at least 30% of the patients, and was more common in the midline solid type tumor. We stress that an attempt of total resection should be done at initial craniotomy. Residual or recurrent tumor are to be resected if they show increasing size on serial CT scans or cause symptoms. Radiotherapy does not afford any additional effects to benign cerebellar astrocytomas. PMID:2835699

  19. Development of quantitative tools for assessment of cerebellar dysfunction

    E-print Network

    Garg, Aditi

    2005-01-01

    Two tools for the quantitative assessment of cerebellar dysfunction are developed and explored. One is based on a battery of laptop tests desgined for clinical use. Extensive analysis of one of the tests using a speed/accuracy ...

  20. The Olivo-Cerebellar System: Dynamical Processes and Computational Principles

    E-print Network

    Loewenstein, Yonatan

    in the inferior olive manifest #12;as physiological and several types of pathological tremors. Therefore the inferior olive neurons with cerebellar Purkinje cells can both increase and decrease the firing rate

  1. Cerebellar Morphology in Tourette Syndrome and Obsessive-Compulsive

    E-print Network

    . Baseline gender differences in cerebellar morphology may in part account for the more prevalent expression and attenuates during adolescence. TS is 3­4 more com- mon in males.1,2 Obsessive-compulsive disorder (OCD

  2. Past, Present and Future Therapeutics for Cerebellar Ataxias

    PubMed Central

    Marmolino, D; Manto, M

    2010-01-01

    Cerebellar ataxias are a group of disabling neurological disorders. Patients exhibit a cerebellar syndrome and can also present with extra-cerebellar deficits, namely pigmentary retinopathy, extrapyramidal movement disorders, pyramidal signs, cortical symptoms (seizures, cognitive impairment/behavioural symptoms), and peripheral neuropathy. Recently, deficits in cognitive operations have been unraveled. Cerebellar ataxias are heterogeneous both at the phenotypic and genotypic point of view. Therapeutical trials performed during these last 4 decades have failed in most cases, in particular because drugs were not targeting a deleterious pathway, but were given to counteract putative defects in neurotransmission. The identification of the causative mutations of many hereditary ataxias, the development of relevant animal models and the recent identifications of the molecular mechanisms underlying ataxias are impacting on the development of new drugs. We provide an overview of the pharmacological treatments currently used in the clinical practice and we discuss the drugs under development. PMID:20808545

  3. Cerebellar giant cell glioblastoma multiforme in an adult

    PubMed Central

    Mishra, Sudhansu Sekhar; Behera, Sanjay Kumar; Dhir, Manmath Kumar; Senapati, Satya Bhusan

    2014-01-01

    Cerebellar glioblastoma multiforme (GBM) is a rare tumor that accounts for only 1% of all cases of GBM and its giant cell variant is even much rarely encountered in adults. A case of cerebellar giant cell GBM managed at our institution reporting its clinical presentation, radiological and histological findings, and treatment instituted is described. In conjunction, a literature review, including particular issues, clinical data, advances in imaging studies, pathological characteristics, treatment options, and the behavior of such malignant tumor is presented. It is very important for the neurosurgeon to make the differential diagnosis between the cerebellar GBM, and other diseases such as metastasis, anaplastic astrocytomas, and cerebellar infarct because their treatment modalities, prognosis, and outcome are different. PMID:25002780

  4. A high and increasing HPV prevalence in tonsillar cancers in Eastern Denmark, 2000-2010: The largest registry-based study to date.

    PubMed

    Garnaes, Emilie; Kiss, Katalin; Andersen, Luise; Therkildsen, Marianne H; Franzmann, Maria B; Filtenborg-Barnkob, Bettina; Hoegdall, Estrid; Krenk, Lene; Josiassen, Michael; Lajer, Christel B; Specht, Lena; Frederiksen, Kirsten; Friis-Hansen, Lennart; Nielsen, Finn C; Kjaer, Susanne K; Norrild, Bodil; von Buchwald, Christian

    2015-05-01

    The aim was to explore whether the incidence of tonsillar squamous cell carcinomas (TSCCs) increased in Eastern Denmark, 2000-2010, and whether human papillomavirus (HPV) could explain the increase, and to assess the association of HPV prevalence with gender, age, and origin (i.e., the certainty of tonsillar tumor origin). We applied HPV DNA PCR and p16 immunohistochemistry to all TSCCs registered in the Danish Head and Neck Cancer Group (DAHANCA) and in the Danish Pathology Data Bank (n?=?632). Pathologists reviewed and subdivided the tumors into two groups: specified and nonspecified TSCCs. Approximately 10% of HPV-positive tumors was genotyped by amplicon next-generation sequencing. The overall crude incidence of TSCCs increased significantly (2.7% per year) and was explained by an increasing incidence of HPV-positive TSCCs (4.9% per year). The overall HPV prevalence was 58%, with HPV16 being the predominant HPV type. In multivariate analysis, the HPV prevalence was associated with age (<55 vs. >60 years) (OR, 1.72; 95% CI 1.13-2.63) and origin (nonspecified vs. specified TSCCs) (OR, 0.15; 95% CI 0.11-0.22). The association of HPV prevalence with origin increased over time in specified TSCCs (OR per year, 1.10; 95% CI 1.01-1.19), whereas no change over time was observed among nonspecified TSCCs (OR per year, 0.99; 95% CI 0.90-1.08). In conclusion, the observed increase in the number of HPV-positive TSCCs can explain the increasing number of TSCCs in Eastern Denmark, 2000-2010. HPV prevalence was associated with younger age (<55 years) and a high certainty of tonsillar tumor origin. PMID:25283302

  5. Cerebellar continuous theta burst stimulation in essential tremor.

    PubMed

    Bologna, Matteo; Rocchi, Lorenzo; Leodori, Giorgio; Paparella, Giulia; Conte, Antonella; Kahn, Nashaba; Fabbrini, Giovanni; Berardelli, Alfredo

    2015-04-01

    The pathophysiological mechanisms of essential tremor (ET) are still not entirely clear. In the present study, we aimed to investigate the cerebello-thalamo-cortical connectivity in ET using the cerebellar continuous theta burst stimulation (cTBS) and possible effects on tremor and reaching movements. Sixteen patients with ET and 11 healthy subjects underwent two experimental sessions: (i) cTBS over the right cerebellar hemisphere (real cerebellar cTBS) and (ii) cTBS over the neck muscles (sham cerebellar cTBS). The two sessions were performed at least 1 week apart. The effects of real and sham cerebellar cTBS were quantified as excitability changes on contralateral primary motor cortex, as well as possible changes of postural tremor and reaching movements on the ipsilateral arm. Primary motor cortex excitability was assessed by recording the input/output curve of the motor-evoked potentials from the right first dorsal interosseous muscle. Tremor was rated clinically. Objective assessment of tremor and reaching movements was performed using kinematic techniques. Real cerebellar cTBS reduced the excitability in the contralateral primary motor cortex in healthy subjects though not in patients with ET. There was no significant change in tremor severity and reaching movements, as assessed by clinical examination or kinematic techniques, after real or sham cerebellar cTBS in patients with ET. Finally, there was no correlation between individual changes of M1 excitability and kinematic measures of tremor and reaching movement abnormalities in patients with ET. The results suggest that functional cerebello-thalamo-cortical connectivity tested by cTBS is abnormal in ET and that cerebellar cTBS does not ameliorate tremor in this condition. PMID:25417188

  6. Effects of topiramate in patients with cerebellar tremor

    Microsoft Academic Search

    GianPietro Sechi; Virgilio Agnetti; Franca M. I. Sulas; GianFranco Sau; Davide Corda; Maria G. Pitzolu; Giulio Rosati

    2003-01-01

    Purpose: To evaluate the safety and potential beneficial effect of topiramate (TPM) as monotherapy or adjunctive therapy to carbamazepine (CBZ) in patients with cerebellar tremor. Methods: Nine patients with cerebellar tremor participated a 4-week, open-label, prospective-controlled trial. TPM was given as monotherapy (n=7 cases), or in combination with CBZ (n=2 cases), at dosages ranging from 25 mg twice daily to

  7. Cerebellar Infarction Following Epidural Abscess after Epidural Neuroplasty

    PubMed Central

    Lee, Hyun Yeong; Wang, Hui Sun; Ju, Chang Il

    2015-01-01

    Epidural neuroplasty is found to be effective in removing fibrous tissue occurring in the epidural space for various reasons. We report a case of cerebellar infarction caused by epidural abscess after epidural neuroplasty. To the best of our knowledge, this is the first report of cerebellar infarction developed as a result of epidural abscess accompanying bacterial meningitis after epidural neuroplasty. We also discuss the etiology, pathogenesis, and prognosis of this rare pathologic entity.

  8. Esophoria or esotropia in adulthood: a sign of cerebellar dysfunction?

    PubMed

    Hüfner, Katharina; Frenzel, Claudia; Kremmyda, Olympia; Adrion, Christine; Bardins, Stanislavs; Glasauer, Stefan; Brandt, Thomas; Strupp, Michael

    2015-03-01

    Convergent strabismus is a common diagnosis in early childhood, when it is mostly considered benign. If it develops later in life, strabismus can, however, be a sign of neurological disease. In these cases the underlying pathophysiological mechanisms are largely unknown. In this retrospective case-control study we analyzed the neuro-ophthalmological examination reports of 400 adult patients who presented at the German Center for Vertigo and Balance Disorders to determine an association between ocular misalignment and cerebellar dysfunction. Patients with cerebellar signs (i.e., cerebellar ataxia and/or cerebellar ocular motor signs) had a 4.49 (95 % CI [1.60; 13.78]) times higher frequency of ocular misalignment and specifically a 13.3 (95 % CI [3.80; 55.73]) times increased frequency of esophoria/esotropia (ESO) during distant gaze than patients without cerebellar dysfunction. ESO when looking into the distance was associated with saccadic smooth pursuit, dysmetria of saccades, and downbeat nystagmus (DBN) (? (2) test, p < 0.0001 for all associations). Patients with cerebellar dysfunction also showed mildly impaired eye abduction (? (2) test, left eye and right eye: p < 0.0001), associated with horizontal gaze-evoked nystagmus (? (2) test, p < 0.0001). The association of ESO and DBN implicates a pathophysiological involvement of the cerebellar flocculus, while the association with dysmetric saccades suggests involvement of the oculomotor vermis. This is compatible with animal studies showing that the pathways of the flocculus/posterior interposed nucleus and vermis/nucleus fastigii are both involved in vergence movements and static binocular alignment. From a clinical point of view, a newly diagnosed esophoria/esotropia only during distant gaze may be a sign of a cerebellar disease. PMID:25522697

  9. Temporal discrimination in the cerebellar cortex during conditioned eyelid responses

    Microsoft Academic Search

    Stephen P. Perrett

    1998-01-01

    Little is known about mechanisms used by the nervous system to encode time. In light of recent evidence, cerebellar cortex\\u000a involvement in the learned timing of conditioned eyelid responses shows promise as an area of investigation into neural timing\\u000a mechanisms. Lesion studies indicate that the cerebellar cortex is necessary for response timing, but do not rule out the possibility\\u000a that

  10. Simultaneous core 2 ?1?6 N-acetylglucosaminyltransferase up-regulation and sialyl-Le X expression during activation of human tonsillar B lymphocytes

    Microsoft Academic Search

    Mitsuru Nakamura; Takashi Ishida; Jiro Kikuchi; Yusuke Furukawa; Michio Matsuda

    1999-01-01

    We have investigated the regulation mechanism of the surface sialyl-LeX (sLeX) expression level in tonsillar B cells during activation. sLeX antigen became strongly positive after activation, while resting B cells were weakly positive. sLeX structures were mainly located on O-linked oligosaccharide chains of glycoprotein. Transcripts of FucT-VII and core 2 GlcNAc transferase (C2GnT) were up-regulated after activation, while those of

  11. Emotions and their cognitive control in children with cerebellar tumors.

    PubMed

    Hopyan, Talar; Laughlin, Suzanne; Dennis, Maureen

    2010-11-01

    A constellation of deficits, termed the cerebellar cognitive affective syndrome (CCAS), has been reported following acquired cerebellar lesions. We studied emotion identification and the cognitive control of emotion in children treated for acquired tumors of the cerebellum. Participants were 37 children (7-16 years) treated for cerebellar tumors (19 benign astrocytomas (AST), 18 malignant medulloblastomas (MB), and 37 matched controls (CON). The Emotion Identification Task investigated recognition of happy and sad emotions in music. In two cognitive control tasks, we investigated whether children could identify emotion in situations in which the emotion in the music and the emotion in the lyrics was either congruent or incongruent. Children with cerebellar tumors identified emotion as accurately and quickly as controls (p > .05), although there was a significant interaction of emotions and group (p < .01), with the MB group performing less accurately identifying sad emotions, and both cerebellar tumor groups were impaired in the cognitive control of emotions (p < .01). The fact that childhood acquired cerebellar tumors disrupt cognitive control of emotion rather than emotion identification provides some support for a model of the CCAS as a disorder, not so much of emotion as of the regulation of emotion by cognition. PMID:20887648

  12. Crew Procedures for Continuous Descent Arrivals Using Conventional Guidance

    NASA Technical Reports Server (NTRS)

    Oseguera-Lohr, Rosa M.; Williams, David H.; Lewis, Elliot T,

    2007-01-01

    This paper presents results from a simulation study which investigated the use of Continuous Descent Arrival (CDA) procedures for conducting a descent through a busy terminal area, using conventional transport-category automation. This research was part of the Low Noise Flight Procedures (LNFP) element within the Quiet Aircraft Technology (QAT) Project, that addressed development of flight guidance, and supporting pilot and Air Traffic Control (ATC) procedures for low noise operations. The procedures and chart were designed to be easy to understand, and to make it easy for the crew to make changes via the Flight Management Computer Control-Display Unit (FMC-CDU) to accommodate changes from ATC. The test runs were intended to represent situations typical of what exists in many of today's terminal areas, including interruptions to the descent in the form of clearances issued by ATC.

  13. Post-Plasmodium vivax malaria cerebellar ataxia and optic neuritis: A new form of delayed cerebellar ataxia or cerebellar variant of acute disseminated encephalomyelitis?

    PubMed Central

    Kasundra, Gaurav M.; Bhargava, Amita Narendra; Bhushan, Bharat; Shubhakaran, Khichar; Sood, Isha

    2015-01-01

    Acute disseminated encephalomyelitis (ADEM) is commonly seen after viral and bacterial infections, immunization, and Plasmodium falciparum (PF) malaria. Plasmodium vivax (PV) rarely causes ADEM. We report a 14-year-old female patient who presented with acute onset bilateral cerebellar ataxia and optic neuritis, 2 weeks after recovery from PV. Magnetic resonance imaging showed bilateral cerebellar hyperintensities suggestive of ADEM. No specific viral etiology was found on cerebrospinal fluid examination. Patient responded well to treatment without any sequelae. Thus, PV too is an important cause of ADEM along with PF. Two of the previously reported cases had co-infection with falciparum malaria. The only other two reported cases, as also this patient, are from Asia. A geographical or racial predisposition needs to be evaluated. Also, a possibility of post-PV delayed cerebellar ataxia, which is classically described post-PF infection, may be considered as it may be clinically, radiologically, and prognostically indistinguishable from a milder presentation of ADEM.

  14. Cerebellar-Motor Dysfunction in Schizophrenia and Psychosis-Risk: The Importance of Regional Cerebellar Analysis Approaches

    PubMed Central

    Bernard, Jessica A.; Mittal, Vijay A.

    2014-01-01

    Motor abnormalities in individuals with schizophrenia and those at-risk for psychosis are well documented. An accumulating body of work has also highlighted motor abnormalities related to cerebellar dysfunction in schizophrenia including eye-blink conditioning, timing, postural control, and motor learning. We have also recently found evidence for motor dysfunction in individuals at ultra high-risk for psychosis (1–3). This is particularly relevant as the cerebellum is thought to be central to the cognitive dysmetria model of schizophrenia, and these overt motor signs may point to more general cerebellar dysfunction in the etiology of psychotic disorders. While studies have provided evidence indicative of motor cerebellar dysfunction in at-risk populations and in schizophrenia, findings with respect to the cerebellum have been mixed. One factor potentially contributing to these mixed results is the whole-structure approach taken when investigating the cerebellum. In non-human primates, there are distinct closed-loop circuits between the cerebellum, thalamus, and brain with motor and non-motor cortical regions. Recent human neuroimaging has supported this finding and indicates that there is a cerebellar functional topography (4), and this information is being missed with whole-structure approaches. Here, we review cerebellar-motor dysfunction in individuals with schizophrenia and those at-risk for psychosis. We also discuss cerebellar abnormalities in psychosis, and the cerebellar functional topography. Because of the segregated functional regions of the cerebellum, we propose that it is important to look at the structure regionally in order to better understand its role in motor dysfunction in these populations. This is analogous to approaches taken with the basal ganglia, where each region is considered separately. Such an approach is necessary to better understand cerebellar pathophysiology on a macro-structural level with respect to the pathogenesis of psychosis. PMID:25505424

  15. Mars Smart Lander Simulations for Entry, Descent, and Landing

    NASA Technical Reports Server (NTRS)

    Striepe, S. A.; Way, D. W.; Balaram, J.

    2002-01-01

    Two primary simulations have been developed and are being updated for the Mars Smart Lander Entry, Descent, and Landing (EDL). The high fidelity engineering end-to-end EDL simulation that is based on NASA Langley's Program to Optimize Simulated Trajectories (POST) and the end-to-end real-time, hardware-in-the-loop simulation testbed, which is based on NASA JPL's (Jet Propulsion Laboratory) Dynamics Simulator for Entry, Descent and Surface landing (DSENDS). This paper presents the status of these Mars Smart Lander EDL end-to-end simulations at this time. Various models, capabilities, as well as validation and verification for these simulations are discussed.

  16. Flight Data Entry, Descent, and Landing (EDL) Repository

    NASA Technical Reports Server (NTRS)

    Martinez, Elmain M.; Winterhalter, Daniel

    2012-01-01

    Dr. Daniel Winterhalter, NASA Engineering and Safety Center Chief Engineer at the Jet Propulsion Laboratory, requested the NASA Engineering and Safety Center sponsor a 3-year effort to collect entry, descent, and landing material and to establish a NASA-wide archive to serve the material. The principle focus of this task was to identify entry, descent, and landing repository material that was at risk of being permanently lost due to damage, decay, and undocumented storage. To provide NASA-wide access to this material, a web-based digital archive was created. This document contains the outcome of the effort.

  17. Entry, Descent and Landing Systems Analysis Study: Phase 1 Report

    NASA Technical Reports Server (NTRS)

    DwyerCianciolo, Alicia M.; Davis, Jody L.; Komar, David R.; Munk, Michelle M.; Samareh, Jamshid A.; Powell, Richard W.; Shidner, Jeremy D.; Stanley, Douglas O.; Wilhite, Alan W.; Kinney, David J.; McGuire, M. Kathleen; Arnold, James O.; Howard, Austin R.; Sostaric, Ronald R.; Studak, Joseph W.; Zumwalt, Carlie H.; Llama, Eduardo G.; Casoliva, Jordi; Ivanov, Mark C.; Clark, Ian; Sengupta, Anita

    2010-01-01

    NASA senior management commissioned the Entry, Descent and Landing Systems Analysis (EDL-SA) Study in 2008 to identify and roadmap the Entry, Descent and Landing (EDL) technology investments that the agency needed to make in order to successfully land large payloads at Mars for both robotic and human-scale missions. This paper summarizes the motivation, approach and top-level results from Year 1 of the study, which focused on landing 10-50 mt on Mars, but also included a trade study of the best advanced parachute design for increasing the landed payloads within the EDL architecture of the Mars Science Laboratory (MSL) mission

  18. Overlooked Degree of Freedom in Steepest Descent Method ---Steepest Descent Method Corresponding to Divergence-Free WKB Method---

    NASA Astrophysics Data System (ADS)

    Hyouguchi, T.; Seto, R.; Adachi, S.

    2009-12-01

    The divergence-free WKB method proposed in our previous papers (T. Hyouguchi, S. Adachi and M. Ueda, Phys. Rev. Lett. 88 (2002), 170404 and T. Hyouguchi, R. Seto, M. Ueda and S. Adachi, Ann. of Phys. 312 (2004), 177) yields a WKB wave function free from divergence for any real argument x in R even around the classical turning point. It is expected in asymptotic analysis that any WKB method for differential equations can be translated in one-to-one manner to the corresponding steepest descent method for integrals. This paper presents newly a steepest descent method that corresponds to our divergence-free WKB method. The experience of this translation lets us notice that the key to improving the traditional steepest descent method for general integrals to become divergence-free is the choice of integration variable to express a given integral.

  19. A taxonomy of descent algorithms for nonlinear programs and variational inequalities

    E-print Network

    Patriksson, Michael

    A taxonomy of descent algorithms for nonlinear programs and variational inequalities Michael describes the problem and the choices of cost approximating mappings and merit functions. The taxonomy. Taxonomy, classification, nonlinear programs, variational inequalities, descent algo­ rithms, cost

  20. The Mars Science Laboratory (MSL) Mars Descent Imager (MARDI) Flight Instrument

    NASA Astrophysics Data System (ADS)

    Malin, M. C.; Caplinger, M. A.; Edgett, K. S.; Ghaemi, F. T.; Ravine, M. A.; Schaffner, J. A.; Maki, J. N.; Willson, R. G.; Bell, J. F.; Cameron, J. F.; Dietrich, W. E.; Edwards, L. J.; Hallet, B.; Herkenhoff, K. E.; Heydari, E.; Kah, L. C.; Lemmon, M. T.; Minitti, M. E.; Olson, T. S.; Parker, T. J.; Rowland, S. K.; Schieber, J.; Sullivan, R. J.; Sumner, D. Y.; Thomas, P. C.; Yingst, R. A.

    2009-03-01

    The MSL Mars Descent Imager (MARDI) flight instrument has been completed and installed on the rover. MARDI will provide hundreds of color images during the descent of MSL to the martian surface in 2012.

  1. Perceptron Learning with Random Coordinate Descent Learning Systems Group, California Institute of Technology

    E-print Network

    Perceptron Learning with Random Coordinate Descent Ling Li Learning Systems Group, California Institute of Technology Abstract. A perceptron is a linear threshold classifier that separates examples a family of random coordinate descent algorithms for perceptron learning on binary classification problems

  2. Polytopes, generating functions, and new statistics related to descents and inversions in permutations

    E-print Network

    Chebikin, Denis

    2008-01-01

    We study new statistics on permutations that are variations on the descent and the inversion statistics. In particular, we consider the alternating descent set of a permutation [sigma] = [sigma] 1 [sigma] 2 an defined as ...

  3. A Cerebellar Neuroprosthetic System: Computational Architecture and in vivo Test.

    PubMed

    Herreros, Ivan; Giovannucci, Andrea; Taub, Aryeh H; Hogri, Roni; Magal, Ari; Bamford, Sim; Prueckl, Robert; Verschure, Paul F M J

    2014-01-01

    Emulating the input-output functions performed by a brain structure opens the possibility for developing neuroprosthetic systems that replace damaged neuronal circuits. Here, we demonstrate the feasibility of this approach by replacing the cerebellar circuit responsible for the acquisition and extinction of motor memories. Specifically, we show that a rat can undergo acquisition, retention, and extinction of the eye-blink reflex even though the biological circuit responsible for this task has been chemically inactivated via anesthesia. This is achieved by first developing a computational model of the cerebellar microcircuit involved in the acquisition of conditioned reflexes and training it with synthetic data generated based on physiological recordings. Secondly, the cerebellar model is interfaced with the brain of an anesthetized rat, connecting the model's inputs and outputs to afferent and efferent cerebellar structures. As a result, we show that the anesthetized rat, equipped with our neuroprosthetic system, can be classically conditioned to the acquisition of an eye-blink response. However, non-stationarities in the recorded biological signals limit the performance of the cerebellar model. Thus, we introduce an updated cerebellar model and validate it with physiological recordings showing that learning becomes stable and reliable. The resulting system represents an important step toward replacing lost functions of the central nervous system via neuroprosthetics, obtained by integrating a synthetic circuit with the afferent and efferent pathways of a damaged brain region. These results also embody an early example of science-based medicine, where on the one hand the neuroprosthetic system directly validates a theory of cerebellar learning that informed the design of the system, and on the other one it takes a step toward the development of neuro-prostheses that could recover lost learning functions in animals and, in the longer term, humans. PMID:25152887

  4. A Cerebellar Neuroprosthetic System: Computational Architecture and in vivo Test

    PubMed Central

    Herreros, Ivan; Giovannucci, Andrea; Taub, Aryeh H.; Hogri, Roni; Magal, Ari; Bamford, Sim; Prueckl, Robert; Verschure, Paul F. M. J.

    2014-01-01

    Emulating the input–output functions performed by a brain structure opens the possibility for developing neuroprosthetic systems that replace damaged neuronal circuits. Here, we demonstrate the feasibility of this approach by replacing the cerebellar circuit responsible for the acquisition and extinction of motor memories. Specifically, we show that a rat can undergo acquisition, retention, and extinction of the eye-blink reflex even though the biological circuit responsible for this task has been chemically inactivated via anesthesia. This is achieved by first developing a computational model of the cerebellar microcircuit involved in the acquisition of conditioned reflexes and training it with synthetic data generated based on physiological recordings. Secondly, the cerebellar model is interfaced with the brain of an anesthetized rat, connecting the model’s inputs and outputs to afferent and efferent cerebellar structures. As a result, we show that the anesthetized rat, equipped with our neuroprosthetic system, can be classically conditioned to the acquisition of an eye-blink response. However, non-stationarities in the recorded biological signals limit the performance of the cerebellar model. Thus, we introduce an updated cerebellar model and validate it with physiological recordings showing that learning becomes stable and reliable. The resulting system represents an important step toward replacing lost functions of the central nervous system via neuroprosthetics, obtained by integrating a synthetic circuit with the afferent and efferent pathways of a damaged brain region. These results also embody an early example of science-based medicine, where on the one hand the neuroprosthetic system directly validates a theory of cerebellar learning that informed the design of the system, and on the other one it takes a step toward the development of neuro-prostheses that could recover lost learning functions in animals and, in the longer term, humans. PMID:25152887

  5. Understanding and modulating motor learning with cerebellar stimulation.

    PubMed

    Celnik, Pablo

    2015-04-01

    Non-invasive brain stimulation techniques are a powerful approach to investigate the physiology and function of the central nervous system. Recent years have seen numerous investigations delivering transcranial magnetic stimulation (TMS) and or transcranial direct current stimulation (tDCS) to the cerebellum to determine its role in motor, cognitive and emotional behaviours. Early studies have shown that it is possible to assess cerebellar-motor cortex (CB-M1) connectivity using a paired-pulse TMS paradigm called cerebellar inhibition (CBI), and indirectly infer the state of cerebellar excitability. Thus, it has been shown that CBI changes proportionally to the magnitude of locomotor learning and in association with reaching adaption tasks. In addition, CBI has been used to demonstrate at a physiological level the effects of applying TMS or tDCS to modulate, up or down, the excitability of cerebellar-M1 connectivity. These studies became the fundamental substrate to newer investigations showing that we can affect motor, cognitive and emotional behaviour when targeting the cerebellum with TMS or tDCS in the context of performance. Furthermore, newer investigations are starting to report the effects of cerebellar non-invasive stimulation to treat symptoms associated with neurological conditions such as stroke and dystonia. Altogether, given the scarcity of current effective therapeutic options, non-invasive cerebellar stimulation can potentially become a game changer for the management of conditions that affect the cerebellum. This brief manuscript presents some of the current evidence demonstrating the effects of cerebellar stimulation to modulate motor behaviour and its use to assess physiological processes underlying motor learning. PMID:25283180

  6. Steepest Descent Path Study of Electron-Transfer Reactions Jianshu Cao

    E-print Network

    Cao, Jianshu

    : October 13, 1999 A nonadiabatic steepest descent path method is developed as a qualitative tool to analyze transfer. I. Introduction The steepest descent path has been widely used as a qualitative tool concept,15-17 and the steepest descent evaluation of the instanton rate recovers the overdamped limit

  7. ONLINE MULTI-LABEL LEARNING WITH ACCELERATED NONSMOOTH STOCHASTIC GRADIENT DESCENT

    E-print Network

    Choi, Seungjin

    ONLINE MULTI-LABEL LEARNING WITH ACCELERATED NONSMOOTH STOCHASTIC GRADIENT DESCENT Sunho Park1 where we minimize the primal form us- ing the accelerated nonsmooth stochastic gradient descent which the primal form using the accelerated nons- mooth stochastic gradient descent [17] which has been recently de

  8. A GENTLE HESSIAN FOR EFFICIENT GRADIENT DESCENT Ronan Collobert and Samy Bengio

    E-print Network

    Collobert, Ronan

    of the time, people rely on simple stochastic gradient descent which has a cost in O(n) per iterationA GENTLE HESSIAN FOR EFFICIENT GRADIENT DESCENT Ronan Collobert and Samy Bengio IDIAP, Martigny, Switzerland {collober,bengio}@idiap.ch ABSTRACT Several second-order optimization methods for gradient descent

  9. Tracer-based determination of vortex descent in the 1999/2000 Arctic winter

    E-print Network

    Chipperfield, Martyn

    , polar vortex, subsidence, descent, stratosphere Citation: Greenblatt, J. B., et al., TracerTracer-based determination of vortex descent in the 1999/2000 Arctic winter Jeffery B. Greenblatt1 vortex has been performed in order to quantify the temporal evolution of vortex descent. Differences

  10. Simulation Results for Airborne Precision Spacing along Continuous Descent Arrivals

    NASA Technical Reports Server (NTRS)

    Barmore, Bryan E.; Abbott, Terence S.; Capron, William R.; Baxley, Brian T.

    2008-01-01

    This paper describes the results of a fast-time simulation experiment and a high-fidelity simulator validation with merging streams of aircraft flying Continuous Descent Arrivals through generic airspace to a runway at Dallas-Ft Worth. Aircraft made small speed adjustments based on an airborne-based spacing algorithm, so as to arrive at the threshold exactly at the assigned time interval behind their Traffic-To-Follow. The 40 aircraft were initialized at different altitudes and speeds on one of four different routes, and then merged at different points and altitudes while flying Continuous Descent Arrivals. This merging and spacing using flight deck equipment and procedures to augment or implement Air Traffic Management directives is called Flight Deck-based Merging and Spacing, an important subset of a larger Airborne Precision Spacing functionality. This research indicates that Flight Deck-based Merging and Spacing initiated while at cruise altitude and well prior to the Terminal Radar Approach Control entry can significantly contribute to the delivery of aircraft at a specified interval to the runway threshold with a high degree of accuracy and at a reduced pilot workload. Furthermore, previously documented work has shown that using a Continuous Descent Arrival instead of a traditional step-down descent can save fuel, reduce noise, and reduce emissions. Research into Flight Deck-based Merging and Spacing is a cooperative effort between government and industry partners.

  11. Whole-body angular momentum during stair ascent and descent.

    PubMed

    Silverman, Anne K; Neptune, Richard R; Sinitski, Emily H; Wilken, Jason M

    2014-04-01

    The generation of whole-body angular momentum is essential in many locomotor tasks and must be regulated in order to maintain dynamic balance. However, angular momentum has not been investigated during stair walking, which is an activity that presents a biomechanical challenge for balance-impaired populations. We investigated three-dimensional whole-body angular momentum during stair ascent and descent and compared it to level walking. Three-dimensional body-segment kinematic and ground reaction force (GRF) data were collected from 30 healthy subjects. Angular momentum was calculated using a 13-segment whole-body model. GRFs, external moment arms and net joint moments were used to interpret the angular momentum results. The range of frontal plane angular momentum was greater for stair ascent relative to level walking. In the transverse and sagittal planes, the range of angular momentum was smaller in stair ascent and descent relative to level walking. Significant differences were also found in the ground reaction forces, external moment arms and net joint moments. The sagittal plane angular momentum results suggest that individuals alter angular momentum to effectively counteract potential trips during stair ascent, and reduce the range of angular momentum to avoid falling forward during stair descent. Further, significant differences in joint moments suggest potential neuromuscular mechanisms that account for the differences in angular momentum between walking conditions. These results provide a baseline for comparison to impaired populations that have difficulty maintaining dynamic balance, particularly during stair ascent and descent. PMID:24636222

  12. Dictionary Learning with Large Step Gradient Descent for Sparse Representations

    E-print Network

    Plumbley, Mark

    Dictionary Learning with Large Step Gradient Descent for Sparse Representations Boris Mailhé.name@eecs.qmul.ac.uk Abstract. This work presents a new algorithm for dictionary learn- ing. Existing algorithms such as MOD and K-SVD often fail to find the best dictionary because they get trapped in a local minimum. Olshausen

  13. Dictionary Learning with Large Step Gradient Descent for Sparse Representations

    E-print Network

    Paris-Sud XI, Université de

    Dictionary Learning with Large Step Gradient Descent for Sparse Representations Boris Mailhé.name@eecs.qmul.ac.uk Abstract. This work presents a new algorithm for dictionary learning. Existing algorithms such as MOD and K-SVD often fail to find the best dictionary because they get trapped in a local minimum. Olshausen and Field

  14. CONSTRUCTIVE AND DESTRUCTIVE FACETS OF WEIL DESCENT ON ELLIPTIC CURVES

    E-print Network

    Gaudry, Pierrick

    , divisor class group, cryptography, elliptic curves. 1 #12; 2 P. GAUDRY, F. HESS, AND N.P. SMART We shallCONSTRUCTIVE AND DESTRUCTIVE FACETS OF WEIL DESCENT ON ELLIPTIC CURVES P. GAUDRY, F. HESS, AND N and Smart for producing curves in the Weil restriction of an elliptic curve over a finite field

  15. CONSTRUCTIVE AND DESTRUCTIVE FACETS OF WEIL DESCENT ON ELLIPTIC CURVES

    E-print Network

    Hess, Florian

    , divisor class group, cryptography, elliptic curves. 1 #12;2 P. GAUDRY, F. HESS, AND N.P. SMART We shallCONSTRUCTIVE AND DESTRUCTIVE FACETS OF WEIL DESCENT ON ELLIPTIC CURVES P. GAUDRY, F. HESS, AND N and Smart for producing curves in the Weil restriction of an elliptic curve over a finite field

  16. Mars Science Laboratory entry, descent, and landing system

    Microsoft Academic Search

    Adam Steltzner; Devin Kipp; Allen Chen; Dan Burkhart; Carl Guernsey; Gavin Mendeck; Robert Mitcheltree; Richard Powell; Tommaso Rivellini; Miguel San Martin

    2006-01-01

    In 2010, the Mars Science Laboratory (MSL) mission will pioneer the next generation of robotic entry, descent, and landing (EDL) systems by delivering the largest and most capable rover to date to the surface of Mars. In addition to landing more mass than prior missions to Mars, MSL will offer access to regions of Mars that have been previously unreachable.

  17. Operation of CONSERT aboard Rosetta during the descent of Philae

    NASA Astrophysics Data System (ADS)

    Hegler, Sebastian; Statz, Christoph; Hahnel, Ronny; Plettemeier, Dirk; Herique, Alain; Kofman, Wlodek

    2013-12-01

    This paper presents a study investigating the performance of using the CONSERT instrument aboard the Rosetta spacecraft as a radar sounder during the Separation-Descent-Landing (SDL) phase of the Rosetta mission. Gathering scientifically valuable data during this phase will support CONSERT's primary target, the reconstruction of the 3D permittivity distribution within the comet 67P/Churyumov-Gerasimenko, by providing a permittivity map of the surface around the landing site. Simulation results will show the performance of the instrument, using a realistic setup including the antenna characteristics of both orbiter and landing unit as well as a realistic orbitography for the descent phase. It will be shown that operating the CONSERT instrument will indeed provide very valuable data, thereby providing tremendous aid to the experiment's main objective. Furthermore, by including knowledge of the antenna characteristics, it is possible to calculate attitude and descent profile of the Philae lander during descent, using the data of the line-of-sight propagation path and the echoes reflected from the comet's surface.

  18. Steepest descent methods for critical points in vector optimization problems

    Microsoft Academic Search

    Thai Doan Chuong; Jen-Chih Yao

    2012-01-01

    In this article, we present steepest descent methods for finding stationary (critical) points of vector optimization problems for maps from an Euclidean space to a Banach space with respect to the partial order induced by a closed, convex and pointed cone with a nonempty interior. Convergence of the generated sequence to a weakly efficient solution of our problem is established

  19. Cortical network functional connectivity in the descent to sleep

    E-print Network

    Larson-Prior, Linda

    sleep is characterized by a sequence of electroencephalographically de- fined stages that may be broadly stages of NREM and then REM sleep progressively disengage the self from the environment. It is now wellCortical network functional connectivity in the descent to sleep Linda J. Larson-Priora,1 , John M

  20. Deformations and descent type theory for Hopf algebras

    E-print Network

    Agore, A L

    2012-01-01

    Let $A \\subset E$ be a given extension of Hopf algebras. A factorization $A$-form of $E$ is a Hopf algebra $H$ such that $E$ factorizes through $A$ and $H$. The bicrossed descent theory asks for the description and classification of all factorization $A$-forms of $E$. The factorization index $[E: A]^f$ is introduced as a numerical measure of the bicrossed descent theory: the extensions of factorization index 1 are those for which a Krull-Schmidt-Azumaya type theorem for bicrossed products holds. The Hopf algebra $H$ is deformed to a new Hopf algebra $H_r$, using a certain type of unitary cocentral map $r: H \\to A$ called a descent map of the matched pair $(A, H, \\triangleright,\\triangleleft)$. This is a general deformation of a given Hopf algebra and it is of interest in its own right. Let $H$ be a given factorization $A$-form of $E$. The description of forms proves that ${\\mathbb H}$ is a factorization $A$-form of $E$ if and only if ${\\mathbb H}$ is isomorphic to $H_{r}$, for some descent map $r: H \\to A$. T...

  1. A Comparison of Inexact Newton and Coordinate Descent Meshoptimization Technqiues

    SciTech Connect

    Diachin, L F; Knupp, P; Munson, T; Shontz, S

    2004-07-08

    We compare inexact Newton and coordinate descent methods for optimizing the quality of a mesh by repositioning the vertices, where quality is measured by the harmonic mean of the mean-ratio metric. The effects of problem size, element size heterogeneity, and various vertex displacement schemes on the performance of these algorithms are assessed for a series of tetrahedral meshes.

  2. Transcendental Brauer elements via descent on elliptic surfaces

    E-print Network

    Viray, Bianca

    2012-01-01

    Transcendental Brauer elements are notoriously difficult to compute. Work of Wittenberg, and later, Ieronymou, gives a method for computing 2-torsion transcendental classes on surfaces that have a genus 1 fibration with rational 2-torsion in the Jacobian fibration. We use ideas from a descent paper of Poonen and Schaefer to remove this assumption on the rational 2-torsion.

  3. Fast Training of Object Detection Using Stochastic Gradient Descent

    Microsoft Academic Search

    Rob G. J. Wijnhoven

    2010-01-01

    Training datasets for object detection problems are typically very large and Support Vector Machine (SVM) implementations are computationally complex. As opposed to these complex techniques, we use Stochastic Gradient Descent (SGD) algorithms that use only a single new training sample in each iteration and process samples in a stream-like fashion. We have incorporated SGD optimization in an object detection framework.

  4. Men of African Descent and Carcinoma of the Prostate Consortium

    Cancer.gov

    The Men of African Descent and Carcinoma of the Prostate (MADCaP) Consortium is collaborating on epidemiologic studies to address the high burden of prostate cancer among this population. These investigators are interested in understanding the complex multifactorial causes of prostate cancer etiology and outcomes among men of African ancestry worldwide.

  5. Identity by Descent in Island-mainland Populations

    Microsoft Academic Search

    Bruce Rannala; J. A. Hartigant

    1995-01-01

    A new model is presented for the genetic structure among a collection of island populations, with fluctuating population sizes and continuous overlapping generations, using a stochastic birth, death and immigration (BDI) process. Immigrants enter each island from a large mainland population, with constant gene frequencies, according to a Poisson process. The average probability of identity by descent (IBD) for two

  6. Semi-Stochastic Gradient Descent Methods Jakub Konecny Peter Richtarik

    E-print Network

    Edinburgh, University of

    to evaluate full gradient at each iteration. Stochastic Gradient Descent (SGD) picks i {1, 2, . . . , n} uniformly at random, and sets xj+1 = xj - hfi (xj). SGD drastically reduces the amount of work that needs the work efficiency of SGD. 2. The Algorithm (S2GD) In the S2GD algorithm, we compute full gradient (gj

  7. Accelerating Stochastic Gradient Descent using Predictive Variance Reduction

    E-print Network

    Johnson, Rie

    evaluation of n derivatives, which is expensive. A popular modification is stochastic gradient descent (SGD) - t it (w(t-1) ). (3) The expectation E[w(t) |w(t-1) ] is identical to (2). A more general version of SGD convergence of O((1 - /L)t ) Nesterov [2004]. However, for SGD, due to the variance of random sampling, we

  8. Women of African Descent: Persistence in Completing Doctorates

    ERIC Educational Resources Information Center

    Iddrisu, Vannetta Bailey

    2010-01-01

    This study examines the educational persistence of women of African descent (WOAD) in pursuit of a doctorate degree at universities in the southeastern United States. WOAD are women of African ancestry born outside the African continent. These women are heirs to an inner dogged determination and spirit to survive despite all odds (Pulliam, 2003,…

  9. Abuse against Women with Disabilities of Mexican Descent: Cultural Considerations

    ERIC Educational Resources Information Center

    Graf, Noreen M.; Reed, Bruce J.; Sanchez, Rubi

    2008-01-01

    Although considerable attention has been focused on violence against women with disabilities, environmental and cultural factors that contribute to this violence have received limited attention. This paper examines violence against women of Mexican descent with disabilities. Recommendations are offered to researchers, educators, and service…

  10. Rapid descent of mesospheric air into the stratospheric polar vortex

    Microsoft Academic Search

    Michael Fisher; Alan O'Neill; Rowan Sutton

    1993-01-01

    Wind fields from a numerical simulation are used to give a detailed Lagrangian picture of air flow in the middle atmosphere of the southern hemisphere in winter and early spring 1991. Trajectories for many thousands of air particles exhibit rapid descent of mesospheric air into the stratospheric polar vortex, revealing its organizing and structure-preserving properties. Results are used to account

  11. Measurement of CPAS Main Parachute Rate of Descent

    NASA Technical Reports Server (NTRS)

    Ray, Eric S.

    2011-01-01

    The Crew Exploration Vehicle Parachute Assembly System (CPAS) is being designed to land the Orion Crew Module (CM) at a safe rate of descent at splashdown. Flight test performance must be measured to a high degree of accuracy to ensure this requirement is met with the most efficient design possible. Although the design includes three CPAS Main parachutes, the requirement is that the system must not exceed 33 ft/s under two Main parachutes, should one of the Main parachutes fail. Therefore, several tests were conducted with clusters of two Mains. All of the steady-state rate of descent data are normalized to standard sea level conditions and checked against the limit. As the Orion design gains weight, the system is approaching this limit to within measurement precision. Parachute "breathing," cluster interactions, and atmospheric anomalies can cause the rate of descent to vary widely and lead to challenges in characterizing parachute terminal performance. An early test had contradictory rate of descent results from optical trajectory and Differential Global Positioning Systems (DGPS). A thorough analysis of the data sources and error propagation was conducted to determine the uncertainty in the trajectory. It was discovered that the Time Space Position Information (TSPI) from the optical tracking provided accurate position data. However, the velocity from TPSI must be computed via numerical differentiation, which is prone to large error. DGPS obtains position through pseudo-range calculations from multiple satellites and velocity through Doppler shift of the carrier frequency. Because the velocity from DGPS is a direct measurement, it is more accurate than TSPI velocity. To remedy the situation, a commercial off-the-shelf product that combines GPS and an Inertial Measurement Unit (IMU) was purchased to significantly improve rate of descent measurements. This had the added benefit of solving GPS dropouts during aircraft extraction. Statistical probability distributions for CPAS Main parachute rate of descent and drag coefficient were computed and plotted. Using test data, a terminal rate of descent at splashdown can be estimated as a function of canopy loading.

  12. Computations of diabatic descent in the stratospheric polar vortex

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.; Newman, Paul A.; Schoeberl, Mark R.

    1994-01-01

    A radiation model, together with National Meteorological Center temperature observations, was used to compute daily net heating rates in the northern hemisphere (NH) for the Arctic late fall and winter periods of both 1988-1989 and 1991-1992 and in the southern hemisphere (SH) for the Antarctic fall and winters of 1987 and 1992. The heating rates were interpolated to potential temperature (theta) surfaces between 400 K and 2000 K and averaged within the polar vortex, the boundary of which was determined by the maximum gradient in potential vorticity. The averaged heating rates were used in a one-dimensional vortex interior descent model to compute the change in potential temperature with time of air parcels initialized at various theta values, as well as to compute the descent in log pressure coodinates. In the NH vortex, air parcels which were initialized at 18 km on November 1, descended about 6 km by March 21, while air initially at 25 km descended 9 km in the same time period. this represents an average descent rate in the lower stratosphere of 1.3 to 2 km per month. Air initialized at 50 km descended 27 km between November 1 and March 21. In the SH vortex, parcels initialized at 18 km on March 1, descended 3 km, while air at 25 km descended 5-7 km by the end of October. This is equivalent to an average descent in the lower stratosphere of 0.4 to 0.9 km per month during this 8-month period. Air initialized at 52 km descended 26-29 km between March 1 and October 31. In both the NH and the SH, computed descent rates increased markedly with height. The descent for the NH winter of 1992-1993 and the SH winter of 1992 computed with a three-dimensional trajectory model using the same radiation code was within 1 to 2 km of that calculated by the one-dimensional model, thus validating the vortex averaging procedure. The computed descent rates generally agree well with observations of long-lived tracers, thus validating the radiative transfer model.

  13. Cerebellar-dependent delay eyeblink conditioning in adolescents with Specific Language Impairment

    E-print Network

    Steinmetz, Adam B.; Rice, Mabel L.

    2010-12-05

    Cerebellar impairments have been hypothesized as part of the pathogenesis of Specific Language Impairment (SLI), although direct evidence of cerebellar involvement is sparse. Eyeblink Conditioning (EBC) is a learning task with well documented...

  14. Cerebellar cortex and cerebellar nuclei are concomitantly activated during eyeblink conditioning: a 7T fMRI study in humans.

    PubMed

    Thürling, Markus; Kahl, Fabian; Maderwald, Stefan; Stefanescu, Roxana M; Schlamann, Marc; Boele, Henk-Jan; De Zeeuw, Chris I; Diedrichsen, Jörn; Ladd, Mark E; Koekkoek, Sebastiaan K E; Timmann, Dagmar

    2015-01-21

    There are controversies whether learning of conditioned eyeblink responses primarily takes place within the cerebellar cortex, the interposed nuclei, or both. It has also been suggested that the cerebellar cortex may be important during early stages of learning, and that there is a shift to the cerebellar nuclei during later stages. As yet, human studies have provided little to resolve this question. In the present study, we established a setup that allows ultra-high-field 7T functional magnetic resonance imaging (fMRI) of the cerebellar cortex and interposed cerebellar nuclei simultaneously during delay eyeblink conditioning in humans. Event-related fMRI signals increased concomitantly in the cerebellar cortex and nuclei during early acquisition of conditioned eyeblink responses in 20 healthy human subjects. ANOVAs with repeated-measures showed significant effects of time across five blocks of 20 conditioning trials in the cortex and nuclei (p < 0.05, permutation corrected). Activations were most pronounced in, but not limited to, lobules VI and interposed nuclei. Increased activations were most prominent at the first time the maximum number of conditioned responses was achieved. Our data are consistent with a simultaneous and synergistic two-site model of learning during acquisition of classically conditioned eyeblinks. Because increased MRI signal reflects synaptic activity, concomitantly increased signals in the cerebellar nuclei and cortex are consistent with findings of learning related potentiation at the mossy fiber to nuclear cell synapse and mossy fiber to granule cell synapse. Activity related to the expression of conditioned responses, however, cannot be excluded. PMID:25609637

  15. Motor learning of mice lacking cerebellar Purkinje cells

    PubMed Central

    Porras-García, M. Elena; Ruiz, Rocío; Pérez-Villegas, Eva M.; Armengol, José Á.

    2013-01-01

    The cerebellum plays a key role in the acquisition and execution of motor tasks whose physiological foundations were postulated on Purkinje cells' long-term depression (LTD). Numerous research efforts have been focused on understanding the cerebellum as a site of learning and/or memory storage. However, the controversy on which part of the cerebellum participates in motor learning, and how the process takes place, remains unsolved. In fact, it has been suggested that cerebellar cortex, deep cerebellar nuclei, and/or their combination with some brain structures other than the cerebellum are responsible for motor learning. Different experimental approaches have been used to tackle this question (cerebellar lesions, pharmacological agonist and/or antagonist of cerebellar neurotransmitters, virus tract tracings, etc.). One of these approaches is the study of spontaneous mutations affecting the cerebellar cortex and depriving it of its main input–output organizer (i.e., the Purkinje cell). In this review, we discuss the results obtained in our laboratory in motor learning of both Lurcher (Lc/+) and tambaleante (tbl/tbl) mice as models of Purkinje-cell-devoid cerebellum. PMID:23630472

  16. An MRI Study of Cerebellar Volume in Tuberous Sclerosis Complex

    PubMed Central

    Weisenfeld, Neil I.; Peters, Jurriaan M.; Tsai, Peter T.; Prabhu, Sanjay P.; Dies, Kira A.; Sahin, Mustafa; Warfield, Simon K.

    2013-01-01

    The cerebellum plays an important role in motor learning and cognition, and structural cerebellar abnormalities have been associated with cognitive impairment. In tuberous sclerosis complex, neurological outcome is highly variable, and no consistent imaging or pathological determinant of cognition has been firmly established. The cerebellum calls for specific attention as mouse models of tuberous sclerosis complex have demonstrated a loss of cerebellar Purkinje cells and cases of human histological data have demonstrated a similar loss in patients. We hypothesized that there might be a common cerebellar finding in tuberous sclerosis complex that could be measured as morphometric changes with magnetic resonance imaging. Using a robust, automated image analysis procedure, we studied 36 patients with tuberous sclerosis complex and age-matched controls and observed significant volume loss among patients in the cerebellar cortices and vermis. Furthermore, this effect was strongest in a subgroup of 19 patients with a known, pathogenic mutation of the tuberous sclerosis 2 gene and impacted all cerebellar structures. We conclude that patients with tuberous sclerosis complex exhibit volume loss in the cerebellum, and this loss is larger and more widespread in patients with a tuberous sclerosis 2 mutation. PMID:23337002

  17. Cerebellar involvement in motor but not sensory adaptation

    PubMed Central

    Block, Hannah J.; Bastian, Amy J.

    2012-01-01

    Predictable sensorimotor perturbations can lead to cerebellum-dependent adaptation—i.e., recalibration of the relationship between sensory input and motor output. Here we asked if the cerebellum is also needed to recalibrate the relationship between two sensory modalities, vision and proprioception. We studied how people with and without cerebellar damage use visual and proprioceptive signals to estimate their hand’s position when the sensory estimates disagree. Theoretically, the brain may resolve the discrepancy by recalibrating the relationship between estimates (sensory realignment). Alternatively, the misalignment may be dealt with by relying less on one sensory estimate and more on the other (a weighting strategy). To address this question, we studied subjects with cerebellar damage and healthy controls as they performed a series of tasks. The first was a prism adaptation task that involves motor adaptation to compensate for a visual perturbation and is known to require the cerebellum. As expected, people with cerebellar damage were impaired relative to controls. The same subjects then performed two experiments in which they reached to visual and proprioceptive targets while a visuoproprioceptive misalignment was gradually imposed. Surprisingly, cerebellar patients performed as well as controls when the task invoked only sensory realignment, but were impaired relative to controls when motor adaptation was also possible. Additionally, individuals with cerebellar damage were able to use a weighting strategy similarly to controls. These results demonstrate that, unlike motor adaptation, sensory realignment and weighting are not cerebellum-dependent. PMID:22554563

  18. Cerebellar dysfunction may play an important role in vascular dementia.

    PubMed

    Sui, Rubo; Zhang, Lei

    2012-01-01

    The cerebellum has traditionally been seen as a brain area limited to the coordination of voluntary movement, gait, posture, speech, and motor functions. There are increasing evidence, however, proving that the cerebellum is implicated in processes associated with the control of cognition, behavior, and psychiatric illness. Furthermore, the fact that the cerebellum is reciprocally connected to a broad range of limbic structures including the amygdale and hippocampus, as well as the cerebral cortex including the prefrontal areas, provides a strong neuroanatomical argument in favor of cerebellar involvement in cognition regulation. Studies have already found the fact that after stroke, the cerebellum suffered from reduction in metabolism and blood flow in the cerebellar hemisphere contralateral to a destructive cerebral lesion. The notion of crossed cerebellar diaschisis (CCD) may contribute to the explanation of the phenomenon. Consequently, theoretically, stroke in any part of the brain including frontal lobe and hippocampus, will affect cerebellar function and the later then results in vascular dementia (VD). More recently, a few clinical trials found that electrical stimulation of fastigial nucleus (FNS) in cerebellum could improve symptom of VD, though the relationship between cerebellum and VD is unclear. Taken together, there seems to be sufficient empirical ground to assume that the cerebellum plays a role in the regulation of VD. The hypotheses of cerebellar role in VD, which will be discussed in this paper, if confirmed, may lead to the formulation of new pathogenesis and new therapeutic approaches to VD. PMID:22075237

  19. [A case of cerebellar infarction with pure dysarthria].

    PubMed

    Ogawa, Katsuhiko; Suzuki, Yutaka; Kamei, Satoshi; Mizutani, Tomohiko

    2004-02-01

    We report a 69-year-old man with pure ataxic speech. He was admitted to the surgical ward of our hospital because of exercise-induced pain in the right arm. He underwent angiography of the right arm, and was discharged the next day. When he returned home, he exhibited an acute-onset dysarthria. He was admitted to our neurology ward the next day because the dysarthria did not improve. On admission, neurological examinations revealed moderately ataxic speech, but other neurological findings were within normal limits. Cranial MRI revealed an infarct localized from the lobulus simplex to the lobulus quadrangularis in the right cerebellum. Three cases of pure dysarthria due to cerebellar infarction have been reported previously. We compared cerebellar lesions in the 4 cases of pure dysarthria due to cerebellar infarction. Since the lobulus simplex of the upper cerebellar hemisphere was involved in all 4 cases, we speculated that ataxic speech occurred from the impairment of this cerebellar area. PMID:15199761

  20. Compartmentation of the Cerebellar Cortex in the Naked Mole-Rat ( Heterocephalus glaber )

    Microsoft Academic Search

    Hassan Marzban; Nathan Hoy; Tooka Aavani; Diana K. Sarko; Kenneth C. Catania; Richard Hawkes

    Despite the apparent uniformity in cellular composition of the adult mammalian cerebellar cortex, it is actually highly compartmentalized\\u000a into transverse zones and within each zone further subdivided into a reproducible array of parasagittal stripes. This basic\\u000a cerebellar architecture is highly conserved in birds and mammals. However, different species have very different cerebellar\\u000a morphologies, and it is unclear if cerebellar architecture

  1. Fast cerebellar oscillation associated with ataxia in a mouse model of angelman syndrome

    Microsoft Academic Search

    G. Cheron; L. Servais; J. Wagstaff; B. Dan

    2005-01-01

    Ataxia may result from various cerebellar cortex dysfunctions. It is included in the diagnostic criteria of Angelman syndrome, a human neurogenetic condition. In order to better understand the cerebellar dysfunction in this condition, we recorded in vivo cerebellar activity in a mouse model of Angelman syndrome produced by null mutation of the maternal Ube3a gene. We found fast oscillation (approximately

  2. Reversible cerebellar ataxia with thyrotoxicosis: An autoimmune brain disease in remission due to Graves’ disease

    PubMed Central

    Prakasha, S. Rama; Suresh, G.; Prakash, P. S.; D'sa, Ivor Peter

    2013-01-01

    We hereby report a patient with seizure disorder who was on long term carbamazepine, admitted with features of thyrotoxicosis and cerebellar dysfunction. Anticonvulsant medications are cerebellar toxins; but in this case, reversal of cerebellar dysfunction was noted upon treatment of thyrotoxicosis with antithyroid drugs. PMID:23869314

  3. Epstein-Barr virus-associated cerebellar ataxia

    PubMed Central

    Ali, Khalid; Lawthom, Charlotte

    2013-01-01

    Cerebellar ataxia is a common neurological presentation. It can be acute, subacute or chronic. Neurological complications of Epstein-Barr virus (EBV) are well-recognised with a variety of presentations. Acute cerebellar ataxia is a rare, but an established complication. It has been described as the sole manifestation of EBV infection without the systemic features of infectious mononucleosis. The pathophysiology is not clear. The course of the illness may last for a few months with a benign outcome, though serious complications can happen. We present a case of a 38-year-old man who presented with an acute cerebellar ataxia owing to EBV infection, along with a review of the literature. PMID:23608862

  4. Paraneoplastic cerebellar degeneration associated with serous adenocarcinoma of the ovary.

    PubMed

    Saeed, Duaa B; Gupta, Limci

    2014-01-01

    We report a case of a 68-year-old woman who presented with symptoms of cerebellar degeneration which initiated a suspicion of underlying malignancy. The patient presented with progressive ataxia and dysarthria and after excluding primary cerebellar pathology, paraneoplastic syndrome was suspected and she was investigated for a malignancy. CT scan of the pelvis showed a left-sided ovarian mass later diagnosed as serous adenocarcinoma of the ovary. She underwent surgery and histology of the mass showed poorly-differentiated serous adenocarcinoma. Paraneoplastic neurological syndrome encompasses several neurological disorders including paraneoplastic cerebellar degeneration (PCD) caused by an immune-mediated mechanism in patients with an underlying malignancy. PCD is a rare condition that occurs in less than 1% of patients with cancer and is associated with specific groups of cancer. It is important to identify PCD due to its association with certain cancers and also to limit the disabilities associated with the syndrome. PMID:25432905

  5. Turning strategies in patients with cerebellar ataxia.

    PubMed

    Mari, Silvia; Serrao, Mariano; Casali, Carlo; Conte, Carmela; Ranavolo, Alberto; Padua, Luca; Draicchio, Francesco; Iavicoli, Sergio; Monamě, Stefano; Sandrini, Giorgio; Pierelli, Francesco

    2012-10-01

    Turning while walking is a common but demanding task requiring modification of the motor program from linear walking to lateral turning and it is associated with a high risk of falls. Patients with cerebellar ataxia have unstable gait and report a high incidence of falls. In the present study, we investigated the motor strategies adopted by ataxic patients when performing turns of different degrees and directions of rotation. Ten ataxic patients and 10 controls were analyzed while performing 30°/90° turns to the right/left. We recorded the number of completed turn tasks, the number of steps needed, and the time taken to complete the task, time-distance parameters and the onset of head, trunk and pelvis reorientation. The ataxic patients were less able to complete 90° turns, displayed a greater stride width, shorter step length, and greater number of steps when turning, and were unable to flexibly adjust their stride width across the turning task. The duration of the turning task and of the segmental reorientation did not differ from control values. Our findings indicate that ataxic patients have more difficulties in performing large turns and adopt a series of compensatory strategy aimed at reducing the instability associated with turning, such as enlarge the base of support, shorten the step length, increase the number of steps, and use the "multi-step" rather than the "spin-turn" strategy. Given the high risk of falls related to this task, it would be useful to include turning training in the rehabilitation protocol of ataxic patients. PMID:22842923

  6. Flight Management System Execution of Idle-Thrust Descents in Operations

    NASA Technical Reports Server (NTRS)

    Stell, Laurel L.

    2011-01-01

    To enable arriving aircraft to fly optimized descents computed by the flight management system (FMS) in congested airspace, ground automation must accurately predict descent trajectories. To support development of the trajectory predictor and its error models, commercial flights executed idle-thrust descents, and the recorded data includes the target speed profile and FMS intent trajectories. The FMS computes the intended descent path assuming idle thrust after top of descent (TOD), and any intervention by the controllers that alters the FMS execution of the descent is recorded so that such flights are discarded from the analysis. The horizontal flight path, cruise and meter fix altitudes, and actual TOD location are extracted from the radar data. Using more than 60 descents in Boeing 777 aircraft, the actual speeds are compared to the intended descent speed profile. In addition, three aspects of the accuracy of the FMS intent trajectory are analyzed: the meter fix crossing time, the TOD location, and the altitude at the meter fix. The actual TOD location is within 5 nmi of the intent location for over 95% of the descents. Roughly 90% of the time, the airspeed is within 0.01 of the target Mach number and within 10 KCAS of the target descent CAS, but the meter fix crossing time is only within 50 sec of the time computed by the FMS. Overall, the aircraft seem to be executing the descents as intended by the designers of the onboard automation.

  7. 3D morphometric analysis of human fetal cerebellar development.

    PubMed

    Scott, Julia A; Hamzelou, Kia S; Rajagopalan, Vidya; Habas, Piotr A; Kim, Kio; Barkovich, A James; Glenn, Orit A; Studholme, Colin

    2012-09-01

    To date, growth of the human fetal cerebellum has been estimated primarily from linear measurements from ultrasound and 2D magnetic resonance imaging (MRI). In this study, we use 3D analytical methods to develop normative growth trajectories for the cerebellum in utero. We measured cerebellar volume, linear dimensions, and local surface curvature from 3D reconstructed MRI of the human fetal brain (N?=?46). We found that cerebellar volume increased approximately 7-fold from 20 to 31 gestational weeks. The better fit of the exponential curve (R (2)?=?0.96) compared to the linear curve (R (2)?=?0.92) indicated acceleration in growth. Within-subject cerebellar and cerebral volumes were highly correlated (R (2)?=?0.94), though the cerebellar percentage of total brain volume increased from approximately 2.4% to 3.7% (R (2)?=?0.63). Right and left hemispheric volumes did not significantly differ. Transcerebellar diameter, vermal height, and vermal anterior to posterior diameter increased significantly at constant rates. From the local curvature analysis, we found that expansion along the inferior and superior aspects of the hemispheres resulted in decreased convexity, which is likely due to the physical constraints of the dura surrounding the cerebellum and the adjacent brainstem. The paired decrease in convexity along the inferior vermis and increased convexity of the medial hemisphere represents development of the paravermian fissure, which becomes more visible during this period. In this 3D morphometric analysis of the human fetal cerebellum, we have shown that cerebellar growth is accelerating at a greater pace than the cerebrum and described how cerebellar growth impacts the shape of the structure. PMID:22198870

  8. [Pediatric medulloblastoma presenting as cerebellar hemorrhage: a case report].

    PubMed

    Furuhata, Masanori; Aihara, Yasuo; Eguchi, Seiichiro; Horiba, Ayako; Tanaka, Masahiko; Komori, Takashi; Okada, Yoshikazu

    2014-06-01

    Medulloblastomas usually cause cerebellar ataxia and acute hydrocephalus owing to their increase in size. Cerebellar hemorrhage is an extremely rare initial clinical presentation of medulloblastoma. Herein, we report a case of medulloblastoma in an 8-year-old girl who presented with initial cerebellar intratumoral hemorrhage. The patient initially presented with mild headache;the differential diagnosis by using the initial computed tomography and magnetic resonance images was difficult, as bleeding from a cerebellar vascular malformation(cavernous angioma or arteriovenous malformation)was considered more likely. Hydrocephalus or typical findings indicative of medulloblastoma were not observed. We initially only observed the patient at another institution because the hematoma was relatively small(1.5×1×1cm). After follow-up imaging for pathological diagnosis, surgical removal was performed at our institute 49 days after the hemorrhage was observed. Complete tumor removal was achieved, and the histopathological diagnosis was medulloblastoma. The patient received whole brain and spinal irradiation(23.4Gy;posterior fossa local:50.4Gy)and chemotherapy(cyclophosphamide, 1,000mg/m2/day on day 1;vincristine, 1.5mg/m2/day on day 1;etoposide, 100mg/m2/day on days 1-3;cisplatin, 90mg/m2/day on day 2). No recurrences or neurological deficits were observed during a 2-year follow-up. This was a rare case of medulloblastoma presenting as cerebellar hemorrhage. Cerebellar medulloblastoma is among the common pediatric brain tumors;therefore, it should be diagnosed accurately and quickly. PMID:24920742

  9. Sudden Onset of Oromandibular Dystonia after Cerebellar Stroke

    PubMed Central

    Akin, Alper; Yilmaz, Rezzak; Selcuk, Ferda; Akbostanc?, M. Cenk

    2014-01-01

    Background We present the case of a 65-year-old female with sudden-onset involuntary mouth opening, deviation of the jaw, facial grimacing, and tongue movements that started 6 months prior to her admission. Case Report She was diagnosed with oromandibular dystonia. Differential diagnosis of oromandibular dystonia and various etiologies were investigated. Neuroimaging studies revealed a left cerebellar infarction. Discussion To our knowledge, this case is the first oromandibular dystonia presenting with cerebellar ischemic stroke. Possible roles of the cerebellum for the pathophysiology of oromandibular dystonia are discussed. PMID:25374766

  10. The contribution of extrasynaptic signaling to cerebellar information processing.

    PubMed

    Coddington, Luke T; Nietz, Angela K; Wadiche, Jacques I

    2014-08-01

    The diversity of synapses within the simple modular structure of the cerebellum has been crucial for study of the phasic extrasynaptic signaling by fast neurotransmitters collectively referred to as "spillover." Additionally, the accessibility of cerebellar components for in vivo recordings and their recruitment by simple behaviors or sensory stimuli has allowed for both direct and indirect demonstrations of the effects of transmitter spillover in the intact brain. The continued study of spillover in the cerebellum not only promotes our understanding of information transfer through cerebellar structures but also how extrasynaptic signaling may be regulated and interpreted throughout the CNS. PMID:24590660

  11. Efficient Sensor Placement Optimization Using Gradient Descent and Probabilistic Coverage

    PubMed Central

    Akbarzadeh, Vahab; Lévesque, Julien-Charles; Gagné, Christian; Parizeau, Marc

    2014-01-01

    We are proposing an adaptation of the gradient descent method to optimize the position and orientation of sensors for the sensor placement problem. The novelty of the proposed method lies in the combination of gradient descent optimization with a realistic model, which considers both the topography of the environment and a set of sensors with directional probabilistic sensing. The performance of this approach is compared with two other black box optimization methods over area coverage and processing time. Results show that our proposed method produces competitive results on smaller maps and superior results on larger maps, while requiring much less computation than the other optimization methods to which it has been compared. PMID:25196164

  12. A Symmetric Time-Varying Cluster Rate of Descent Model

    NASA Technical Reports Server (NTRS)

    Ray, Eric S.

    2015-01-01

    A model of the time-varying rate of descent of the Orion vehicle was developed based on the observed correlation between canopy projected area and drag coefficient. This initial version of the model assumes cluster symmetry and only varies the vertical component of velocity. The cluster fly-out angle is modeled as a series of sine waves based on flight test data. The projected area of each canopy is synchronized with the primary fly-out angle mode. The sudden loss of projected area during canopy collisions is modeled at minimum fly-out angles, leading to brief increases in rate of descent. The cluster geometry is converted to drag coefficient using empirically derived constants. A more complete model is under development, which computes the aerodynamic response of each canopy to its local incidence angle.

  13. A conjugate gradient method with descent direction for unconstrained optimization

    NASA Astrophysics Data System (ADS)

    Yuan, Gonglin; Lu, Xiwen; Wei, Zengxin

    2009-11-01

    A modified conjugate gradient method is presented for solving unconstrained optimization problems, which possesses the following properties: (i) The sufficient descent property is satisfied without any line search; (ii) The search direction will be in a trust region automatically; (iii) The Zoutendijk condition holds for the Wolfe-Powell line search technique; (iv) This method inherits an important property of the well-known Polak-Ribičre-Polyak (PRP) method: the tendency to turn towards the steepest descent direction if a small step is generated away from the solution, preventing a sequence of tiny steps from happening. The global convergence and the linearly convergent rate of the given method are established. Numerical results show that this method is interesting.

  14. Steepest Descent Algorithms for Optimization Under Unitary Matrix Constraint

    Microsoft Academic Search

    Traian E. Abrudan; Jan Eriksson; Visa Koivunen

    2008-01-01

    In many engineering applications we deal with constrained optimization problems with respect to complex-valued matrices. This paper proposes a Riemannian geometry approach for optimization of a real-valued cost function T of complex-valued matrix argument W, under the constraint that W is an n times n unitary matrix. We derive steepest descent (SD) algorithms on the Lie group of unitary matrices

  15. Inflammatory Bowel Disease in Children of Middle Eastern Descent

    PubMed Central

    Naidoo, Christina Mai Ying; Leach, Steven T.; Day, Andrew S.; Lemberg, Daniel A.

    2014-01-01

    Increasing rates of inflammatory bowel disease (IBD) are now seen in populations where it was once uncommon. The pattern of IBD in children of Middle Eastern descent in Australia has never been reported. This study aimed to investigate the burden of IBD in children of Middle Eastern descent at the Sydney Children's Hospital, Randwick (SCHR). The SCHR IBD database was used to identify patients of self-reported Middle Eastern ethnicity diagnosed between 1987 and 2011. Demographic, diagnosis, and management data was collected for all Middle Eastern children and an age and gender matched non-Middle Eastern IBD control group. Twenty-four patients of Middle Eastern descent were identified. Middle Eastern Crohn's disease patients had higher disease activity at diagnosis, higher use of thiopurines, and less restricted colonic disease than controls. Although there were limitations with this dataset, we estimated a higher prevalence of IBD in Middle Eastern children and they had a different disease phenotype and behavior compared to the control group, with less disease restricted to the colon and likely a more active disease course. PMID:24987422

  16. Factors Associated with Sleep Disturbance in Women of Mexican Descent

    PubMed Central

    Heilemann, MarySue V.; Choudhury, Shonali M.; Kury, Felix Salvador; Lee, Kathryn A.

    2014-01-01

    Aims The aims were to identify the most useful parameters of acculturation in relation to self reported sleep disturbance and describe risk factors for sleep disturbance in women of Mexican descent. Background Little is known about acculturation as a factor for poor sleep in the context of other personal factors such as income or sense of resilience or mastery for Latinas in the United States. Methods These personal factors were incorporated into a modification of the Conceptual Framework of Impaired Sleep to guide our secondary analysis of self-reported sleep disturbance. Cross sectional data from a convenience sample of 312 women of Mexican descent of childbearing age (21-40 years) located in an urban California community were collected and previously analyzed in relation to depressive symptoms and post traumatic stress disorder. The General Sleep Disturbance Scale (in English and Spanish) was used to assess sleep disturbance. Results Early socialization to the United States during childhood was the most useful acculturation parameter for understanding self reported sleep disturbance in this sample. In a multivariate regression analysis, three factors (higher acculturation, lower income, and higher depressive symptoms) were significant in accounting for 40% of the variance in sleep disturbance. Conclusion When low income Latinas of Mexican descent report sleep problems, clinicians should probe for environmental sleep factors associated with low income, such as noise, over-crowding, and exposure to trauma and violence, and refer the woman to psychotherapy and counselling rather than merely prescribe a sleep medication. PMID:22221152

  17. Free-falls and parachute descents in the standard atmosphere

    NASA Technical Reports Server (NTRS)

    Webster, A P

    1947-01-01

    A detailed table of the standard equilibrium velocity and standard equilibrium time is presented for bodies falling in the standard atmosphere. This table gives the velocity at various altitudes and the time of fall from sea level to -4000 feet and from 80,000 feet to sea level. In addition to this standard table, there are given short tables and charts of an open-parachute descent and free-falls; the terminal velocity at sea level, and the variation of the weight-to-drag ratio (2w/cds)1/2 for various weight jumpers from 90 to 30 feet in open-parachute descent; and estimations of drag coefficients of silk and nylon parachutes. The table of standard equilibrium velocities and standard equilibrium times may be used directly for open-parachute descents, given the weight of the jumper, the diameter of the parachute, and the drag coefficient. For free-falls starting from horizontal flight, approximately 14 seconds must be added to the equilibrium time given in the table to obtain the total time to sea level. (author)

  18. Data-Analysis System for Entry, Descent, and Landing

    NASA Technical Reports Server (NTRS)

    Pham, Timothy; Chang, Christine; Sartorius, Edgar; Finley, Susan; White, Leslie; Estabrook, Polly; Fort, David

    2005-01-01

    A report describes the Entry Descent Landing Data Analysis (EDA), which is a system of signal-processing software and computer hardware for acquiring status data conveyed by multiple-frequency-shift-keying tone signals transmitted by a spacecraft during descent to the surface of a remote planet. The design of the EDA meets the challenge of processing weak, fluctuating signals that are Doppler-shifted by amounts that are only partly predictable. The software supports both real-time and post processing. The software performs fast-Fourier-transform integration, parallel frequency tracking with prediction, and mapping of detected tones to specific events. The use of backtrack and refinement parallel-processing threads helps to minimize data gaps. The design affords flexibility to enable division of a descent track into segments, within each of which the EDA is configured optimally for processing in the face of signal conditions and uncertainties. A dynamic-lock-state feature enables the detection of signals using minimum required computing power less when signals are steadily detected, more when signals fluctuate. At present, the hardware comprises eight dual-processor personal-computer modules and a server. The hardware is modular, making it possible to increase computing power by adding computers.

  19. Hazard avoidance via descent images for safe landing

    NASA Astrophysics Data System (ADS)

    Yan, Ruicheng; Cao, Zhiguo; Zhu, Lei; Fang, Zhiwen

    2013-10-01

    In planetary or lunar landing missions, hazard avoidance is critical for landing safety. Therefore, it is very important to correctly detect hazards and effectively find a safe landing area during the last stage of descent. In this paper, we propose a passive sensing based HDA (hazard detection and avoidance) approach via descent images to lower the landing risk. In hazard detection stage, a statistical probability model on the basis of the hazard similarity is adopted to evaluate the image and detect hazardous areas, so that a binary hazard image can be generated. Afterwards, a safety coefficient, which jointly utilized the proportion of hazards in the local region and the inside hazard distribution, is proposed to find potential regions with less hazards in the binary hazard image. By using the safety coefficient in a coarse-to-fine procedure and combining it with the local ISD (intensity standard deviation) measure, the safe landing area is determined. The algorithm is evaluated and verified with many simulated descent downward looking images rendered from lunar orbital satellite images.

  20. Titan Explorer Entry, Descent and Landing Trajectory Design

    NASA Technical Reports Server (NTRS)

    Fisher, Jody L.; Lindberg, Robert E.; Lockwood, Mary Kae

    2006-01-01

    The Titan Explorer mission concept includes an orbiter, entry probe and inflatable airship designed to take remote and in-situ measurements of Titan's atmosphere. A modified entry, descent and landing trajectory at Titan that incorporates mid-air airship inflation (under a parachute) and separation is developed and examined for Titan Explorer. The feasibility of mid-air inflation and deployment of an airship under a parachute is determined by implementing and validating an airship buoyancy and inflation model in the trajectory simulation program, Program to Optimize Simulated Trajectories II (POST2). A nominal POST2 trajectory simulation case study is generated which examines different descent scenarios by varying airship inflation duration, orientation, and separation. The buoyancy model incorporation into POST2 is new to the software and may be used in future trajectory simulations. Each case from the nominal POST2 trajectory case study simulates a successful separation between the parachute and airship systems with sufficient velocity change as to alter their paths to avoid collision throughout their descent. The airship and heatshield also separate acceptably with a minimum distance of separation from the parachute system of 1.5 km. This analysis shows the feasibility of airship inflation on a parachute for different orientations, airship separation at various inflation times, and preparation for level-flight at Titan.

  1. Airborne Management of Traffic Conflicts in Descent With Arrival Constraints

    NASA Technical Reports Server (NTRS)

    Doble, Nathan A.; Barhydt, Richard; Krishnamurthy, Karthik

    2005-01-01

    NASA is studying far-term air traffic management concepts that may increase operational efficiency through a redistribution of decisionmaking authority among airborne and ground-based elements of the air transportation system. One component of this research, En Route Free Maneuvering, allows trained pilots of equipped autonomous aircraft to assume responsibility for traffic separation. Ground-based air traffic controllers would continue to separate traffic unequipped for autonomous operations and would issue flow management constraints to all aircraft. To evaluate En Route Free Maneuvering operations, a human-in-the-loop experiment was jointly conducted by the NASA Ames and Langley Research Centers. In this experiment, test subject pilots used desktop flight simulators to resolve conflicts in cruise and descent, and to adhere to air traffic flow constraints issued by test subject controllers. Simulators at NASA Langley were equipped with a prototype Autonomous Operations Planner (AOP) flight deck toolset to assist pilots with conflict management and constraint compliance tasks. Results from the experiment are presented, focusing specifically on operations during the initial descent into the terminal area. Airborne conflict resolution performance in descent, conformance to traffic flow management constraints, and the effects of conflicting traffic on constraint conformance are all presented. Subjective data from subject pilots are also presented, showing perceived levels of workload, safety, and acceptability of autonomous arrival operations. Finally, potential AOP functionality enhancements are discussed along with suggestions to improve arrival procedures.

  2. Transient cerebellar mutism in the course of acute cerebellitis

    Microsoft Academic Search

    Antigone S Papavasiliou; Charalambos Kotsalis; Stamos Trakadas

    2004-01-01

    Transient mutism after posterior fossa surgery in children or associated with cerebellar hemorrhage or trauma is a recognized phenomenon. However, its association with parainflammatory cerebellitis has been rarely described. We report on a previously healthy 3-year-old child with severe cerebellitis after acute gastroenteritis of unidentified cause. Severe ataxia and transient mutism were the prevailing clinical features. Magnetic resonance imaging revealed

  3. Cerebellar network plasticity: From genes to fast oscillation

    Microsoft Academic Search

    G. Cheron; L. Servais; B. Dan

    2008-01-01

    The role of the cerebellum has been increasingly recognized not only in motor control but in sensory, cognitive and emotional learning and regulation. Purkinje cells, being the sole output from the cerebellar cortex, occupy an integrative position in this network. Plasticity at this level is known to critically involve calcium signaling. In the last few years, electrophysiological study of genetically

  4. Long term modification of cerebellar inhibition after inferior olive degeneration

    Microsoft Academic Search

    C. Batini; J. M. Billard; H. Daniel

    1985-01-01

    The long term effects of inferior olive destruction on the activities of the Purkinje cells and their target neurones in the cerebellar nuclei were studied in the rat. Careful observations were also made of motor behaviour throughout the study. Albino rats were injected with 3-acetylpyridine to produce a neurotoxic destruction of the inferior olive and then were used for acute

  5. Cerebellar zonal patterning relies on Purkinje cell neurotransmission.

    PubMed

    White, Joshua J; Arancillo, Marife; Stay, Trace L; George-Jones, Nicholas A; Levy, Sabrina L; Heck, Detlef H; Sillitoe, Roy V

    2014-06-11

    Cerebellar circuits are patterned into an array of topographic parasagittal domains called zones. The proper connectivity of zones is critical for motor coordination and motor learning, and in several neurological diseases cerebellar circuits degenerate in zonal patterns. Despite recent advances in understanding zone function, we still have a limited understanding of how zones are formed. Here, we focused our attention on Purkinje cells to gain a better understanding of their specific role in establishing zonal circuits. We used conditional mouse genetics to test the hypothesis that Purkinje cell neurotransmission is essential for refining prefunctional developmental zones into sharp functional zones. Our results show that inhibitory synaptic transmission in Purkinje cells is necessary for the precise patterning of Purkinje cell zones and the topographic targeting of mossy fiber afferents. As expected, blocking Purkinje cell neurotransmission caused ataxia. Using in vivo electrophysiology, we demonstrate that loss of Purkinje cell communication altered the firing rate and pattern of their target cerebellar nuclear neurons. Analysis of Purkinje cell complex spike firing revealed that feedback in the cerebellar nuclei to inferior olive to Purkinje cell loop is obstructed. Loss of Purkinje neurotransmission also caused ectopic zonal expression of tyrosine hydroxylase, which is only expressed in adult Purkinje cells when calcium is dysregulated and if excitability is altered. Our results suggest that Purkinje cell inhibitory neurotransmission establishes the functional circuitry of the cerebellum by patterning the molecular zones, fine-tuning afferent circuitry, and shaping neuronal activity. PMID:24920627

  6. Medulloblastoma or cerebellar dysplastic gangliocytoma (Lhermitte-Duclos disease)?

    Microsoft Academic Search

    Kuo-Shin Chen; Po-Cheng Hung; Huei-Shyong Wang; Shih-Ming Jung; Shu-Hang Ng

    2002-01-01

    Dysplastic cerebellar gangliocytoma is a rare benign tumor associated with specific neuroimaging findings of abnormal laminated or folial pattern in the posterior fossa. Some authors thus proposed that it could be diagnosed by neuroimaging studies alone. We encountered a patient with medulloblastoma in which the neuroimaging findings mimicked those of dysplastic gangliocytoma. In patients with a posterior fossa tumor suggestive

  7. Torticollis acquired in late infancy due to a cerebellar gangliocytoma

    Microsoft Academic Search

    James B. Caress; Virinder Nohria; Herbert Fuchs; Rose-Mary Boustany

    1996-01-01

    Torticollis in infancy is a common disorder and is typically benign and self-limiting. However, in some instances it is the presentation of serious disease. A critical distinction is whether the condition is congenital or acquired. We present a case of acquired late infantile torticollis caused by a cerebellar gangliocytoma that underscores the importance of making this determination prior to initiating

  8. Cerebral and cerebellar gangliocytomas: a morphological study of nine cases

    Microsoft Academic Search

    I. Felix; J. M. Bilbao; S. L. Asa; F. Tyndel; K. Kovacs; L. E. Becker

    1994-01-01

    Hypothalamic gangliocytomas have been shown to contain immunoreactivity for hypophysiotropic peptides and some have been associated with endocrine dysfunction. Extrahypothalamic gangliocytomas are usually not associated with endocrine abnormalities. We studied nine cerebral or cerebellar gangliocytomas from six men and three women; none of the patients had detectable alterations of endocrine homeostasis. On histological examination, the tumor cells resembled hypothalamic neurons.

  9. Late effects of radiotherapy on patients with cerebellar medulloblastoma

    Microsoft Academic Search

    C. L. Silverman; H. Palkes; B. Talent; E. Kovnar; J. W. Clouse; Prm Thomas

    1984-01-01

    Nine long-term survivors of cerebellar medulloblastoma treated with surgery and irradiation were retrospectively examined with a complete battery of neuropsychological tests and the results compared with their nonirradiated siblings. Significant decreased scores were found in the full-scale intelligence quotients (IQ), performance IQ, and verbal IQ with all nine irradiated patients scoring below their siblings. Also, educational quotients (EQ) of the

  10. Cerebellar Zonal Patterning Relies on Purkinje Cell Neurotransmission

    PubMed Central

    White, Joshua J.; Arancillo, Marife; Stay, Trace L.; George-Jones, Nicholas A.; Levy, Sabrina L.; Heck, Detlef H.

    2014-01-01

    Cerebellar circuits are patterned into an array of topographic parasagittal domains called zones. The proper connectivity of zones is critical for motor coordination and motor learning, and in several neurological diseases cerebellar circuits degenerate in zonal patterns. Despite recent advances in understanding zone function, we still have a limited understanding of how zones are formed. Here, we focused our attention on Purkinje cells to gain a better understanding of their specific role in establishing zonal circuits. We used conditional mouse genetics to test the hypothesis that Purkinje cell neurotransmission is essential for refining prefunctional developmental zones into sharp functional zones. Our results show that inhibitory synaptic transmission in Purkinje cells is necessary for the precise patterning of Purkinje cell zones and the topographic targeting of mossy fiber afferents. As expected, blocking Purkinje cell neurotransmission caused ataxia. Using in vivo electrophysiology, we demonstrate that loss of Purkinje cell communication altered the firing rate and pattern of their target cerebellar nuclear neurons. Analysis of Purkinje cell complex spike firing revealed that feedback in the cerebellar nuclei to inferior olive to Purkinje cell loop is obstructed. Loss of Purkinje neurotransmission also caused ectopic zonal expression of tyrosine hydroxylase, which is only expressed in adult Purkinje cells when calcium is dysregulated and if excitability is altered. Our results suggest that Purkinje cell inhibitory neurotransmission establishes the functional circuitry of the cerebellum by patterning the molecular zones, fine-tuning afferent circuitry, and shaping neuronal activity. PMID:24920627

  11. Neurodevelopmental Outcomes in Children with Cerebellar Malformations: A Systematic Review

    ERIC Educational Resources Information Center

    Bolduc, Marie-Eve; Limperopoulos, Catherine

    2009-01-01

    Cerebellar malformations are increasingly diagnosed in the fetal period. Consequently, their consideration requires stressful and often critical decisions from both clinicians and families. This has resulted in an emergent need to understand better the impact of these early life lesions on child development. We performed a comprehensive literature…

  12. Cerebellar rTMS disrupts predictive language processing

    PubMed Central

    Lesage, Elise; Morgan, Blaire E.; Olson, Andrew C.; Meyer, Antje S.; Miall, R. Chris

    2012-01-01

    Summary The human cerebellum plays an important role in language, amongst other cognitive and motor functions [1], but a unifying theoretical framework about cerebellar language function is lacking. In an established model of motor control, the cerebellum is seen as a predictive machine, making short-term estimations about the outcome of motor commands. This allows for flexible control, on-line correction, and coordination of movements [2]. The homogeneous cytoarchitecture of the cerebellar cortex suggests that similar computations occur throughout the structure, operating on different input signals and with different output targets [3]. Several authors have therefore argued that this ‘motor’ model may extend to cerebellar nonmotor functions [3–5], and that the cerebellum may support prediction in language processing [6]. However, this hypothesis has never been directly tested. Here, we used the ‘Visual World’ paradigm [7], where on-line processing of spoken sentence content can be assessed by recording the latencies of listeners' eye movements towards objects mentioned. Repetitive transcranial magnetic stimulation (rTMS) was used to disrupt function in the right cerebellum, a region implicated in language [8]. After cerebellar rTMS, listeners showed delayed eye fixations to target objects predicted by sentence content, while there was no effect on eye fixations in sentences without predictable content. The prediction deficit was absent in two control groups. Our findings support the hypothesis that computational operations performed by the cerebellum may support prediction during both motor control and language processing. PMID:23017990

  13. The myelination of the cerebellar cortex in the cat

    Microsoft Academic Search

    W. Lange; Hochschule Aachen

    1978-01-01

    The myelination of the cerebellar cortex of the cat was investigated in 61 cats aged from 3 hrs post partum to two and a half years. The first myelinated fibers appear at the time of birth in the central medullary ray. Before the onset of myelination, all fibers reach a critical diameter of about 1 µm. About the 14th day

  14. Spectrum of the Posterior Inferior Cerebellar Artery Territory Infarcts

    Microsoft Academic Search

    Emre Kumral; Ceyla Ataç; Nilgün Yünten

    2005-01-01

    Background and Purpose: The clinical, etiological and stroke mechanisms are defined well before but the detailed clinical and etiologic mechanisms regarding to all clinical spectrum of posterior inferior cerebellar artery (PICA) infarcts were not systematically studied by diffusion-weighted imaging (DWI). Methods: Seventy-four patients with PICA territory ischemic lesion proved by DWI with decreased apparent diffusion coefficient and FLAIR (fluid attenuation

  15. Longitudinal Tracking of Gait and Balance Impairments in Cerebellar Disease

    PubMed Central

    Morton, Susanne M.; Tseng, Ya-Weng; Zackowski, Kathleen M.; Daline, Jaclyn R.; Bastian, Amy J.

    2010-01-01

    Cerebellar damage typically results in ataxia and can be caused by stroke, tumor or one of many forms of degenerative disease. Since few pharmacological options are available, most treatments rely heavily on rehabilitation therapy. Little data exist on methods for tracking the progression of ataxia, which is critical for assessing the efficacy of current and newly developing treatments. Here, we tracked the severity of ataxia, with a particular emphasis on gait and balance dysfunction, in a group of individuals with cerebellar damage using the International Cooperative Ataxia Rating Scale (ICARS) and several instrumented laboratory measures of gait and balance impairments over one year. We found that the ICARS was able to distinguish between subjects with static lesions and those with degenerative disorders, was sensitive to increases in ataxia severity occurring over one year, and correlated well with specific instrumented measures of gait in persons with cerebellar degeneration. These results suggest the ICARS is a valuable tool for clinicians and investigators to document and track long-term changes in gait and balance performance in individuals with cerebellar degenerative disorders. PMID:20544808

  16. Eyeblink Conditioning Deficits Indicate Timing and Cerebellar Abnormalities in Schizophrenia

    ERIC Educational Resources Information Center

    Brown, S.M.; Kieffaber, P.D.; Carroll, C.A.; Vohs, J.L.; Tracy, J.A.; Shekhar, A.; O'Donnell, B.F.; Steinmetz, J.E.; Hetrick, W.P.

    2005-01-01

    Accumulating evidence indicates that individuals with schizophrenia manifest abnormalities in structures (cerebellum and basal ganglia) and neurotransmitter systems (dopamine) linked to internal-timing processes. A single-cue tone delay eyeblink conditioning paradigm comprised of 100 learning and 50 extinction trials was used to examine cerebellar

  17. Speech and Language Findings Associated with Paraneoplastic Cerebellar Degeneration

    ERIC Educational Resources Information Center

    Paslawski, Teresa; Duffy, Joseph R.; Vernino, Steven

    2005-01-01

    Paraneoplastic cerebellar degeneration (PCD) is an autoimmune disease that can be associated with cancer of the breast, lung, and ovary. The clinical presentation of PCD commonly includes ataxia, visual disturbances, and dysarthria. The speech disturbances associated with PCD have not been well characterized, despite general acceptance that…

  18. Cerebellar Damage Produces Selective Deficits in Verbal Working Memory

    ERIC Educational Resources Information Center

    Ravizza, Susan M.; Mccormick, Cristin A.; Schlerf, John E.; Justus, Timothy; Ivry, Richard B.; Fiez, Julie A.

    2006-01-01

    The cerebellum is often active in imaging studies of verbal working memory, consistent with a putative role in articulatory rehearsal. While patients with cerebellar damage occasionally exhibit a mild impairment on standard neuropsychological tests of working memory, these tests are not diagnostic for exploring these processes in detail. The…

  19. Hippocampo-cerebellar theta band phase synchrony in rabbits.

    PubMed

    Wikgren, J; Nokia, M S; Penttonen, M

    2010-02-17

    Hippocampal functioning, in the form of theta band oscillation, has been shown to modulate and predict cerebellar learning of which rabbit eyeblink conditioning is perhaps the most well-known example. The contribution of hippocampal neural activity to cerebellar learning is only possible if there is a functional connection between the two structures. Here, in the context of trace eyeblink conditioning, we show (1) that, in addition to the hippocampus, prominent theta oscillation also occurs in the cerebellum, and (2) that cerebellar theta oscillation is synchronized with that in the hippocampus. Further, the degree of phase synchrony (PS) increased both as a response to the conditioning stimuli and as a function of the relative power of hippocampal theta oscillation. However, the degree of PS did not change as a function of either training or learning nor did it predict learning rate as the hippocampal theta ratio did. Nevertheless, theta band synchronization might reflect the formation of transient neural assemblies between the hippocampus and the cerebellum. These findings help us understand how hippocampal function can affect eyeblink conditioning, during which the critical plasticity occurs in the cerebellum. Future studies should examine cerebellar unit activity in relation to hippocampal theta oscillations in order to discover the detailed mechanisms of theta-paced neural activity. PMID:19945512

  20. Taurine Protects Immature Cerebellar Granullar Neurons against Acute Alcohol Administration

    Microsoft Academic Search

    Andrey G. Taranukhin; Elena Y. Taranukhina; Irina M. Djatchkova; Pirjo Saransaari; Markku Pelto-Huikko; Simo S. Oja

    Acute ethanol administration causes extensive apoptosis throughout the nervous system. We studied the protective effect of\\u000a taurine on alcohol-induced apoptosis in the cerebellum of developing mice. Taurine rescued a part of immature neurons by markedly\\u000a reducing caspase-3 immunoreactivity and the number of TUNEL-positive cells in most cerebellar lobules.

  1. Clinical manifestations of cerebellar infarction according to specific lobular involvement.

    PubMed

    Ye, Byoung Seok; Kim, Young Dae; Nam, Hyo Suk; Lee, Hye Sun; Nam, Chung Mo; Heo, Ji Hoe

    2010-12-01

    Lesions in the cerebellum produce various symptoms related to balance and motor coordination. However, the relationship between the exact topographical localization of a lesion and the resulting symptoms is not well understood in humans. In this study, we analyzed 66 consecutive patients with isolated cerebellar infarctions demonstrated on diffusion-weighted magnetic resonance imaging. We identified the involved lobules in these patients using a cross-referencing tool of the picture archiving and communication system, and we investigated the relationships between the sites of the lesions and specific symptoms using ? (2) tests and logistic regression analysis. The most common symptoms in patients with isolated cerebellar infarctions were vertigo (87%) and lateropulsion (82%). Isolated vertigo or lateropulsion without any other symptoms was present in 38% of patients. On the other hand, limb ataxia was a presenting symptom in only 40% of the patients. Lateropulsion, vertigo, and nystagmus were more common in patients with a lesion in the caudal vermis. Logistic regression analysis showed that lesions in the posterior paravermis or nodulus were independently associated with lateropulsion. Lesions in the nodulus were associated with contralateral pulsion, and involvement of the culmen was associated with ipsilateral pulsion and isolated lateropulsion without vertigo. Nystagmus was associated with lesions in the pyramis lobule, while lesions of the anterior paravermis were associated with dysarthria and limb ataxia. Our results showed that the cerebellar lobules are responsible for producing specific symptoms in cerebellar stroke patients. PMID:20711853

  2. Diffusion tensor imaging of the human cerebellar pathways and their interplay with cerebral macrostructure

    PubMed Central

    Keser, Zafer; Hasan, Khader M.; Mwangi, Benson I.; Kamali, Arash; Ucisik-Keser, Fehime Eymen; Riascos, Roy F.; Yozbatiran, Nuray; Francisco, Gerard E.; Narayana, Ponnada A.

    2015-01-01

    Cerebellar white matter (WM) connections to the central nervous system are classified functionally into the Spinocerebellar (SC), vestibulocerebellar (VC), and cerebrocerebellar subdivisions. The SC pathways project from spinal cord to cerebellum, whereas the VC pathways project from vestibular organs of the inner ear. Cerebrocerebellar connections are composed of feed forward and feedback connections between cerebrum and cerebellum including the cortico-ponto-cerebellar (CPC) pathways being of cortical origin and the dentate-rubro-thalamo-cortical (DRTC) pathway being of cerebellar origin. In this study we systematically quantified the whole cerebellar system connections using diffusion tensor magnetic resonance imaging (DT-MRI). Ten right-handed healthy subjects (7 males and 3 females, age range 20–51 years) were studied. DT-MRI data were acquired with a voxel size = 2 mm × 2 mm × 2 mm at a 3.0 Tesla clinical MRI scanner. The DT-MRI data were prepared and analyzed using anatomically-guided deterministic tractography methods to reconstruct the SC, DRTC, fronto-ponto-cerebellar (FPC), parieto-ponto-cerebellar (PPC), temporo-ponto-cerebellar (TPC) and occipito-ponto-cerebellar (OPC). The DTI-attributes or the cerebellar tracts along with their cortical representation (Brodmann areas) were presented in standard Montréal Neurological Institute space. All cerebellar tract volumes were quantified and correlated with volumes of cerebral cortical, subcortical gray matter (GM), cerebral WM and cerebellar GM, and cerebellar WM. On our healthy cohort, the ratio of total cerebellar GM-to-WM was ~3.29 ± 0.24, whereas the ratio of cerebral GM-to-WM was approximately 1.10 ± 0.11. The sum of all cerebellar tract volumes is ~25.8 ± 7.3 mL, or a percentage of 1.6 ± 0.45 of the total intracranial volume (ICV). PMID:25904851

  3. Mars Science Laboratory: Entry, Descent, and Landing System Performance

    NASA Technical Reports Server (NTRS)

    Way, David W.; Powell, Richard W.; Chen, Allen; SanMartin, A. Miguel; Burkhart, P. Daniel; Mendeck, Gavin F.

    2007-01-01

    In 2010, the Mars Science Laboratory (MSL) mission will pioneer the next generation of robotic Entry, Descent, and Landing (EDL) systems, by delivering the largest and most capable rover to date to the surface of Mars. To do so, MSL will fly a guided lifting entry at a lift-to-drag ratio in excess of that ever flown at Mars, deploy the largest parachute ever at Mars, and perform a novel Sky Crane maneuver. Through improved altitude capability, increased latitude coverage, and more accurate payload delivery, MSL is allowing the science community to consider the exploration of previously inaccessible regions of the planet. The MSL EDL system is a new EDL architecture based on Viking heritage technologies and designed to meet the challenges of landing increasing massive payloads on Mars. In accordance with level-1 requirements, the MSL EDL system is being designed to land an 850 kg rover to altitudes as high as 1 km above the Mars Orbiter Laser Altimeter defined areoid within 10 km of the desired landing site. Accordingly, MSL will enter the largest entry mass, fly the largest 70 degree sphere-cone aeroshell, generate the largest hypersonic lift-to-drag ratio, and deploy the largest Disk-Gap-Band supersonic parachute of any previous mission to Mars. Major EDL events include a hypersonic guided entry, supersonic parachute deploy and inflation, subsonic heatshield jettison, terminal descent sensor acquisition, powered descent initiation, sky crane terminal descent, rover touchdown detection, and descent stage flyaway. Key performance metrics, derived from level-1 requirements and tracked by the EDL design team to indicate performance capability and timeline margins, include altitude and range at parachute deploy, time on radar, and propellant use. The MSL EDL system, which will continue to develop over the next three years, will enable a notable extension in the advancement of Mars surface science by delivering more science capability than ever before to the surface of Mars. This paper describes the current MSL EDL system performance as predicted by end-to-end EDL simulations, highlights the sensitivity of this baseline performance to several key environmental assumptions, and discusses some of the challenges faced in delivering such an unprecedented rover payload to the surface of Mars.

  4. Adaptive robotic control driven by a versatile spiking cerebellar network.

    PubMed

    Casellato, Claudia; Antonietti, Alberto; Garrido, Jesus A; Carrillo, Richard R; Luque, Niceto R; Ros, Eduardo; Pedrocchi, Alessandra; D'Angelo, Egidio

    2014-01-01

    The cerebellum is involved in a large number of different neural processes, especially in associative learning and in fine motor control. To develop a comprehensive theory of sensorimotor learning and control, it is crucial to determine the neural basis of coding and plasticity embedded into the cerebellar neural circuit and how they are translated into behavioral outcomes in learning paradigms. Learning has to be inferred from the interaction of an embodied system with its real environment, and the same cerebellar principles derived from cell physiology have to be able to drive a variety of tasks of different nature, calling for complex timing and movement patterns. We have coupled a realistic cerebellar spiking neural network (SNN) with a real robot and challenged it in multiple diverse sensorimotor tasks. Encoding and decoding strategies based on neuronal firing rates were applied. Adaptive motor control protocols with acquisition and extinction phases have been designed and tested, including an associative Pavlovian task (Eye blinking classical conditioning), a vestibulo-ocular task and a perturbed arm reaching task operating in closed-loop. The SNN processed in real-time mossy fiber inputs as arbitrary contextual signals, irrespective of whether they conveyed a tone, a vestibular stimulus or the position of a limb. A bidirectional long-term plasticity rule implemented at parallel fibers-Purkinje cell synapses modulated the output activity in the deep cerebellar nuclei. In all tasks, the neurorobot learned to adjust timing and gain of the motor responses by tuning its output discharge. It succeeded in reproducing how human biological systems acquire, extinguish and express knowledge of a noisy and changing world. By varying stimuli and perturbations patterns, real-time control robustness and generalizability were validated. The implicit spiking dynamics of the cerebellar model fulfill timing, prediction and learning functions. PMID:25390365

  5. Adaptive Robotic Control Driven by a Versatile Spiking Cerebellar Network

    PubMed Central

    Casellato, Claudia; Antonietti, Alberto; Garrido, Jesus A.; Carrillo, Richard R.; Luque, Niceto R.; Ros, Eduardo; Pedrocchi, Alessandra; D'Angelo, Egidio

    2014-01-01

    The cerebellum is involved in a large number of different neural processes, especially in associative learning and in fine motor control. To develop a comprehensive theory of sensorimotor learning and control, it is crucial to determine the neural basis of coding and plasticity embedded into the cerebellar neural circuit and how they are translated into behavioral outcomes in learning paradigms. Learning has to be inferred from the interaction of an embodied system with its real environment, and the same cerebellar principles derived from cell physiology have to be able to drive a variety of tasks of different nature, calling for complex timing and movement patterns. We have coupled a realistic cerebellar spiking neural network (SNN) with a real robot and challenged it in multiple diverse sensorimotor tasks. Encoding and decoding strategies based on neuronal firing rates were applied. Adaptive motor control protocols with acquisition and extinction phases have been designed and tested, including an associative Pavlovian task (Eye blinking classical conditioning), a vestibulo-ocular task and a perturbed arm reaching task operating in closed-loop. The SNN processed in real-time mossy fiber inputs as arbitrary contextual signals, irrespective of whether they conveyed a tone, a vestibular stimulus or the position of a limb. A bidirectional long-term plasticity rule implemented at parallel fibers-Purkinje cell synapses modulated the output activity in the deep cerebellar nuclei. In all tasks, the neurorobot learned to adjust timing and gain of the motor responses by tuning its output discharge. It succeeded in reproducing how human biological systems acquire, extinguish and express knowledge of a noisy and changing world. By varying stimuli and perturbations patterns, real-time control robustness and generalizability were validated. The implicit spiking dynamics of the cerebellar model fulfill timing, prediction and learning functions. PMID:25390365

  6. Cerebellar Purkinje cell p75 neurotrophin receptor and autistic behavior.

    PubMed

    Lotta, L T; Conrad, K; Cory-Slechta, D; Schor, N F

    2014-01-01

    The p75 neurotrophin receptor (p75NTR) is normally expressed in cerebellar Purkinje cells throughout the lifespan. Children with autism spectrum behavior exhibit apparent cerebellar Purkinje cell loss. Cerebellar transcriptome changes seen in the murine prenatal valproate exposure model of autism include all of the proteins known to constitute the p75NTR interactome. p75NTR is a modulator of cytoplasmic and mitochondrial redox potential, and others have suggested that aberrant response to oxidant stress has a major role in the pathogenesis of autism. We have created Purkinje cell-selective p75NTR knockout mice that are the progeny of hemizygous Cre-Purkinje cell protein 2 C57Bl mice and p75NTR floxed C57Bl mice. These Cre-loxP mice exhibit complete knockout of p75NTR in ~50% of the cerebellar Purkinje cells. Relative to Cre-only mice and wild-type C57Bl mice, this results in a behavioral phenotype characterized by less allogrooming of (P<0.05; one-way analysis of variance) and socialization or fighting with (each P<0.05) other mice; less (1.2-fold) non-ambulatory exploration of their environment than wild-type (P<0.01) or Cre only (P<0.01) mice; and almost twofold more stereotyped jumping behavior than wild-type (P<0.05) or Cre (P<0.02) mice of the same strain. Wild-type mice have more complex dendritic arborization than Cre-loxP mice, with more neurites per unit area (P<0.025, Student's t-test), more perpendicular branches per unit area (P<0.025) and more short branches/long neurite (P<0.0005). Aberrant developmental regulation of expression of p75NTR in cerebellar Purkinje cells may contribute to the pathogenesis of autism. PMID:25072321

  7. Automated MRI cerebellar size measurements using active appearance modeling.

    PubMed

    Price, Mathew; Cardenas, Valerie A; Fein, George

    2014-12-01

    Although the human cerebellum has been increasingly identified as an important hub that shows potential for helping in the diagnosis of a large spectrum of disorders, such as alcoholism, autism, and fetal alcohol spectrum disorder, the high costs associated with manual segmentation, and low availability of reliable automated cerebellar segmentation tools, has resulted in a limited focus on cerebellar measurement in human neuroimaging studies. We present here the CATK (Cerebellar Analysis Toolkit), which is based on the Bayesian framework implemented in FMRIB's FIRST. This approach involves training Active Appearance Models (AAMs) using hand-delineated examples. CATK can currently delineate the cerebellar hemispheres and three vermal groups (lobules I-V, VI-VII, and VIII-X). Linear registration with the low-resolution MNI152 template is used to provide initial alignment, and Point Distribution Models (PDM) are parameterized using stellar sampling. The Bayesian approach models the relationship between shape and texture through computation of conditionals in the training set. Our method varies from the FIRST framework in that initial fitting is driven by 1D intensity profile matching, and the conditional likelihood function is subsequently used to refine fitting. The method was developed using T1-weighted images from 63 subjects that were imaged and manually labeled: 43 subjects were scanned once and were used for training models, and 20 subjects were imaged twice (with manual labeling applied to both runs) and used to assess reliability and validity. Intraclass correlation analysis shows that CATK is highly reliable (average test-retest ICCs of 0.96), and offers excellent agreement with the gold standard (average validity ICC of 0.87 against manual labels). Comparisons against an alternative atlas-based approach, SUIT (Spatially Unbiased Infratentorial Template), that registers images with a high-resolution template of the cerebellum, show that our AAM approach offers superior reliability and validity. Extensions of CATK to cerebellar hemisphere parcels are envisioned. PMID:25192657

  8. Functional Relations of Cerebellar Modules of the Cat

    PubMed Central

    Pong, Milton; Gibson, Alan R.

    2010-01-01

    The cerebellum consists of parasagittal zones that define fundamental modules of neural processing. Each zone receives input from a distinct subdivision of the inferior olive (IO)—activity in one olivary subdivision will affect activity in one cerebellar module. To define functions of the cerebellar modules, we inactivated specific olivary subdivisions in six male cats with a glutamate receptor blocker. Olivary inactivation eliminates Purkinje cell complex spikes, which results in a high rate of Purkinje cell simple spike discharge. The increased simple spike discharge inhibits output from connected regions of the cerebellar nuclei. After inactivation, behavior was evaluated during a reach-to-grasp task and during locomotion. Inactivation of each subdivision produced unique behavioral deficits. Performance of the reach-to-grasp task was affected by inactivation of the rostral dorsal accessory olive (rDAO) and the rostral medial accessory olive (rMAO) and, possibly, the principal olive. rDAO inactivation produced paw drag during locomotion and a deficit in grasping the handle during the reach-to-grasp task. rMAO inactivation caused the cats to reach under the handle and produced severe limb drag during locomotion. Inactivation of the dorsal medial cell column, cell group ?, or caudal medial accessory olive produced little deficit in the reach-to-grasp task, but each produced a different deficit during locomotion. In all cases, the cats appeared to have intact sensation, good spatial awareness, and no change of affect. Normal cerebellar function requires low rates of IO discharge, and each cerebellar module has a specific and unique function in sensory–motor integration. PMID:20631170

  9. Cerebellar Purkinje cell p75 neurotrophin receptor and autistic behavior

    PubMed Central

    Lotta, L T; Conrad, K; Cory-Slechta, D; Schor, N F

    2014-01-01

    The p75 neurotrophin receptor (p75NTR) is normally expressed in cerebellar Purkinje cells throughout the lifespan. Children with autism spectrum behavior exhibit apparent cerebellar Purkinje cell loss. Cerebellar transcriptome changes seen in the murine prenatal valproate exposure model of autism include all of the proteins known to constitute the p75NTR interactome. p75NTR is a modulator of cytoplasmic and mitochondrial redox potential, and others have suggested that aberrant response to oxidant stress has a major role in the pathogenesis of autism. We have created Purkinje cell-selective p75NTR knockout mice that are the progeny of hemizygous Cre-Purkinje cell protein 2 C57Bl mice and p75NTR floxed C57Bl mice. These Cre-loxP mice exhibit complete knockout of p75NTR in ~50% of the cerebellar Purkinje cells. Relative to Cre-only mice and wild-type C57Bl mice, this results in a behavioral phenotype characterized by less allogrooming of (P<0.05; one-way analysis of variance) and socialization or fighting with (each P<0.05) other mice; less (1.2-fold) non-ambulatory exploration of their environment than wild-type (P<0.01) or Cre only (P<0.01) mice; and almost twofold more stereotyped jumping behavior than wild-type (P<0.05) or Cre (P<0.02) mice of the same strain. Wild-type mice have more complex dendritic arborization than Cre-loxP mice, with more neurites per unit area (P<0.025, Student's t-test), more perpendicular branches per unit area (P<0.025) and more short branches/long neurite (P<0.0005). Aberrant developmental regulation of expression of p75NTR in cerebellar Purkinje cells may contribute to the pathogenesis of autism. PMID:25072321

  10. STS-1 operational flight profile. Volume 5: Descent, cycle 3. Appendix C: Monte Carlo dispersion analysis

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The results of three nonlinear the Monte Carlo dispersion analyses for the Space Transportation System 1 Flight (STS-1) Orbiter Descent Operational Flight Profile, Cycle 3 are presented. Fifty randomly selected simulation for the end of mission (EOM) descent, the abort once around (AOA) descent targeted line are steep target line, and the AOA descent targeted to the shallow target line are analyzed. These analyses compare the flight environment with system and operational constraints on the flight environment and in some cases use simplified system models as an aid in assessing the STS-1 descent flight profile. In addition, descent flight envelops are provided as a data base for use by system specialists to determine the flight readiness for STS-1. The results of these dispersion analyses supersede results of the dispersion analysis previously documented.

  11. Aberrant cerebellar development of transgenic mice expressing dominant-negative thyroid hormone receptor in cerebellar purkinje cells.

    PubMed

    Yu, Lu; Iwasaki, Toshiharu; Xu, Ming; Lesmana, Ronny; Xiong, Yu; Shimokawa, Noriaki; Chin, William W; Koibuchi, Noriyuki

    2015-04-01

    To study the role of the thyroid hormone (TH) in cerebellar development, we generated transgenic mice expressing a dominant-negative TH receptor (TR) in cerebellar Purkinje cells. A mutant human TR?1 (G345R), which binds to the TH-response element but cannot bind to T3, was subcloned into exon 4 of the full-length L7/Pcp-2 gene, which is specifically expressed in Purkinje and retinal rod bipolar cells. The transgene was specifically expressed in Purkinje cells in the postnatal cerebellum. Purkinje cell dendrite arborization was significantly delayed in the transgenic mice. Surprisingly, granule cell migration was also significantly delayed. In the primary cerebellar culture, TH-induced Purkinje cell dendrite arborization was also suppressed. In quantitative real-time RT-PCR analysis, the expression levels of several TH-responsive genes were altered. The expression levels of inositol trisphosphate receptor type 1 and retinoic acid receptor-related orphan receptor? mRNAs, which are mainly expressed in Purkinje cells, and brain-derived neurotrophic factor mRNA, which is expressed in both Purkinje and granule cells, were significantly decreased. The expression levels of neurotrophin-3 and hairless mRNAs, which are mainly expressed in granule cells, and myelin basic protein mRNA, which is mainly expressed in oligodendrocytes, were also decreased. The motor coordination of transgenic mice was significantly disrupted. These results indicate that TH action through its binding to TR in Purkinje cells is required for the normal cerebellar development. TH action through TR in Purkinje cells is also important for the development of other subsets of cerebellar cells such as granule cells and oligodendrocytes. PMID:25603044

  12. Development of Cerebellar Neurons and Glias Revealed by in Utero Electroporation: Golgi-Like Labeling of Cerebellar Neurons and Glias

    PubMed Central

    Kita, Yoshiaki; Kawakami, Koichi; Takahashi, Yoshiko; Murakami, Fujio

    2013-01-01

    Cerebellar cortical functions rely on precisely arranged cytoarchitectures composed of several distinct types of neurons and glias. Studies have indicated that cerebellar excitatory and inhibitory neurons have distinct spatial origins, the upper rhombic lip (uRL) and ventricular zone (VZ), respectively, and that different types of neurons have different birthdates. However, the spatiotemporal relationship between uRL/VZ progenitors and their final phenotype remains poorly understood due to technical limitations. To address this issue, we performed in utero electroporation (IUE) of fluorescent protein plasmids using mouse embryos to label uRL/VZ progenitors at specific developmental stages, and observed labeled cells at maturity. To overcome any potential dilution of the plasmids caused by progenitor division, we also utilized constructs that enable permanent labeling of cells. Cerebellar neurons and glias were labeled in a Golgi-like manner enabling ready identification of labeled cells. Five types of cerebellar neurons, namely Purkinje, Golgi, Lugaro and unipolar brush cells, large-diameter deep nuclei (DN) neurons, and DN astrocytes were labeled by conventional plasmids, whereas plasmids that enable permanent labeling additionally labeled stellate, basket, and granule cells as well as three types of glias. IUE allows us to label uRL/VZ progenitors at different developmental stages. We found that the five types of neurons and DN astrocytes were labeled in an IUE stage-dependent manner, while stellate, basket, granule cells and three types of glias were labeled regardless of the IUE stage. Thus, the results indicate the IUE is an efficient method to track the development of cerebellar cells from uRL/VZ progenitors facing the ventricular lumen. They also indicate that while the generation of the five types of neurons by uRL/VZ progenitors is regulated in a time-dependent manner, the progenitor pool retains multipotency throughout embryonic development. PMID:23894597

  13. Cerebellar Transcranial Direct Current Stimulation (ctDCS): A Novel Approach to Understanding Cerebellar Function in Health and Disease.

    PubMed

    Grimaldi, Giuliana; Argyropoulos, Georgios P; Bastian, Amy; Cortes, Mar; Davis, Nicholas J; Edwards, Dylan J; Ferrucci, Roberta; Fregni, Felipe; Galea, Joseph M; Hamada, Masahi; Manto, Mario; Miall, R Chris; Morales-Quezada, Leon; Pope, Paul A; Priori, Alberto; Rothwell, John; Tomlinson, S Paul; Celnik, Pablo

    2014-11-18

    The cerebellum is critical for both motor and cognitive control. Dysfunction of the cerebellum is a component of multiple neurological disorders. In recent years, interventions have been developed that aim to excite or inhibit the activity and function of the human cerebellum. Transcranial direct current stimulation of the cerebellum (ctDCS) promises to be a powerful tool for the modulation of cerebellar excitability. This technique has gained popularity in recent years as it can be used to investigate human cerebellar function, is easily delivered, is well tolerated, and has not shown serious adverse effects. Importantly, the ability of ctDCS to modify behavior makes it an interesting approach with a potential therapeutic role for neurological patients. Through both electrical and non-electrical effects (vascular, metabolic) ctDCS is thought to modify the activity of the cerebellum and alter the output from cerebellar nuclei. Physiological studies have shown a polarity-specific effect on the modulation of cerebellar-motor cortex connectivity, likely via cerebellar-thalamocortical pathways. Modeling studies that have assessed commonly used electrode montages have shown that the ctDCS-generated electric field reaches the human cerebellum with little diffusion to neighboring structures. The posterior and inferior parts of the cerebellum (i.e., lobules VI-VIII) seem particularly susceptible to modulation by ctDCS. Numerous studies have shown to date that ctDCS can modulate motor learning, and affect cognitive and emotional processes. Importantly, this intervention has a good safety profile; similar to when applied over cerebral areas. Thus, investigations have begun exploring ctDCS as a viable intervention for patients with neurological conditions. PMID:25406224

  14. An evaluation of descent strategies for TNAV-equipped aircraft in an advanced metering environment

    NASA Technical Reports Server (NTRS)

    Izumi, K. H.; Schwab, R. W.; Groce, J. L.; Coote, M. A.

    1986-01-01

    Investigated were the effects on system throughput and fleet fuel usage of arrival aircraft utilizing three 4D RNAV descent strategies (cost optimal, clean-idle Mach/CAS and constant descent angle Mach/CAS), both individually and in combination, in an advanced air traffic control metering environment. Results are presented for all mixtures of arrival traffic consisting of three Boeing commercial jet types and for all combinations of the three descent strategies for a typical en route metering airport arrival distribution.

  15. What is the best way of measuring perineal descent? A comparison of radiographic and clinical methods.

    PubMed

    Oettle, G J; Roe, A M; Bartolo, D C; Mortensen, N J

    1985-12-01

    The 'perineometer' underestimated movement of the pelvic floor by nearly 60 per cent in 21 patients tested; mean descent was 1.2 cm, compared with a radiographic mean descent of 2.9 cm (P less than 0.001). Since the instrument measures movement of the anal verge, not the pelvic floor, no account is taken of anal canal shortening. Radiographic methods are still necessary for the reliable identification of abnormal descent. PMID:4084759

  16. Cerebellar white matter pathways are associated with reading skills in children and adolescents.

    PubMed

    Travis, Katherine E; Leitner, Yael; Feldman, Heidi M; Ben-Shachar, Michal

    2015-04-01

    Reading is a critical life skill in the modern world. The neural basis of reading incorporates a distributed network of cortical areas and their white matter connections. The cerebellum has also been implicated in reading and reading disabilities. However, little is known about the contribution of cerebellar white matter pathways to major component skills of reading. We used diffusion magnetic resonance imaging (dMRI) with tractography to identify the cerebellar peduncles in a group of 9- to 17-year-old children and adolescents born full term (FT, n?=?19) or preterm (PT, n?=?26). In this cohort, no significant differences were found between fractional anisotropy (FA) measures of the peduncles in the PT and FT groups. FA of the cerebellar peduncles correlated significantly with measures of decoding and reading comprehension in the combined sample of FT and PT subjects. Correlations were negative in the superior and inferior cerebellar peduncles and positive in the middle cerebellar peduncle. Additional analyses revealed that FT and PT groups demonstrated similar patterns of reading associations within the left superior cerebellar peduncle, middle cerebellar peduncle, and left inferior cerebellar peduncle. Partial correlation analyses showed that distinct sub-skills of reading were associated with FA in segments of different cerebellar peduncles. Overall, the present findings are the first to document associations of microstructure of the cerebellar peduncles and the component skills of reading. Hum Brain Mapp 36:1536-1553, 2015. © 2014 Wiley Periodicals, Inc. PMID:25504986

  17. In and out of the loop: external and internal modulation of the olivo-cerebellar loop

    PubMed Central

    Libster, Avraham M.; Yarom, Yosef

    2013-01-01

    Cerebellar anatomy is known for its crystal like structure, where neurons and connections are precisely and repeatedly organized with minor variations across the Cerebellar Cortex. The olivo-cerebellar loop, denoting the connections between the Cerebellar cortex, Inferior Olive and Cerebellar Nuclei (CN), is also modularly organized to form what is known as the cerebellar module. In contrast to the relatively organized and static anatomy, the cerebellum is innervated by a wide variety of neuromodulator carrying axons that are heterogeneously distributed along the olivo-cerebellar loop, providing heterogeneity to the static structure. In this manuscript we review modulatory processes in the olivo-cerebellar loop. We start by discussing the relationship between neuromodulators and the animal behavioral states. This is followed with an overview of the cerebellar neuromodulatory signals and a short discussion of why and when the cerebellar activity should be modulated. We then devote a section for three types of neurons where we briefly review its properties and propose possible neuromodulation scenarios. PMID:23626524

  18. Fagg, Sitkoff, Barto, & Houk: A Computational Model of Cerebellar Learning for Limb Control; NCM 97 1 A Computational Model of Cerebellar Learning

    E-print Network

    Massachusetts at Amherst, University of

    the arm to the specified target. Via proprioceptive inputs, the modeled inferior olive assesses the inferior olive. Here, we present a model of cerebellar learning for limb control which repre­ sents one the inferior olive) may not be necessary. Instead, our model indirectly de­ rives cerebellar training

  19. Powered Descent Guidance with General Thrust-Pointing Constraints

    NASA Technical Reports Server (NTRS)

    Carson, John M., III; Acikmese, Behcet; Blackmore, Lars

    2013-01-01

    The Powered Descent Guidance (PDG) algorithm and software for generating Mars pinpoint or precision landing guidance profiles has been enhanced to incorporate thrust-pointing constraints. Pointing constraints would typically be needed for onboard sensor and navigation systems that have specific field-of-view requirements to generate valid ground proximity and terrain-relative state measurements. The original PDG algorithm was designed to enforce both control and state constraints, including maximum and minimum thrust bounds, avoidance of the ground or descent within a glide slope cone, and maximum speed limits. The thrust-bound and thrust-pointing constraints within PDG are non-convex, which in general requires nonlinear optimization methods to generate solutions. The short duration of Mars powered descent requires guaranteed PDG convergence to a solution within a finite time; however, nonlinear optimization methods have no guarantees of convergence to the global optimal or convergence within finite computation time. A lossless convexification developed for the original PDG algorithm relaxed the non-convex thrust bound constraints. This relaxation was theoretically proven to provide valid and optimal solutions for the original, non-convex problem within a convex framework. As with the thrust bound constraint, a relaxation of the thrust-pointing constraint also provides a lossless convexification that ensures the enhanced relaxed PDG algorithm remains convex and retains validity for the original nonconvex problem. The enhanced PDG algorithm provides guidance profiles for pinpoint and precision landing that minimize fuel usage, minimize landing error to the target, and ensure satisfaction of all position and control constraints, including thrust bounds and now thrust-pointing constraints.

  20. Selective expansion of T cell receptor (TCR) V beta 6 in tonsillar and peripheral blood T cells and its induction by in vitro stimulation with Haemophilus parainfluenzae in patients with IgA nephropathy

    PubMed Central

    Nozawa, H; Takahara, M; Yoshizaki, T; Goto, T; Bandoh, N; Harabuchi, Y

    2008-01-01

    IgA nephropathy (IgAN), the most common form of primary glomerulonephritis, is recognized as a disease that often becomes worse during acute tonsillitis. Although many reports have shown that tonsillectomy is an effective treatment for IgAN patients, the immunological evidence has not yet been investigated fully. In this study, we compared the expression of T cell receptor (TCR) V beta families in tonsillar T cells of IgAN patients to those of non-IgAN patients. The reverse transcription–polymerase chain reaction (RT–PCR) and flow cytometric analyses showed that the TCR V beta 6 was used more frequently in tonsillar T cells of IgAN patients than in those of non-IgAN patients (P < 0·01 each). Similarly, the proportions of TCR V beta 6-positive cells in peripheral blood T cells were significantly higher in IgAN patients than in non-IgAN patients (P < 0·05). After tonsillectomy, the proportions decreased in IgAN patients (P < 0·05), but did not in non-IgAN patients. Furthermore, in vitro stimulation with Haemophilus parainfluenzae antigen, which is reported to deposit in the glomerular mesangium of IgAN, enhanced expression of TCR V beta 6 in tonsillar T cells from both IgAN and non-IgAN patients. These results suggest that TCR V beta 6-positive tonsillar T cells might be activated by H. parainfluenzae, move into the kidney through blood circulation and induce glomerulonephritis. PMID:17983447

  1. [Thyrotoxic hypokalemic periodic paralysis in patients of African descent].

    PubMed

    Maia, Morgana Lima e; Trevisam, Paula Grasiele Carvalho; Minicucci, Marcos; Mazeto, Glaucia M F S; Azevedo, Paula S

    2014-10-01

    Thyrotoxic hypokalemic periodic paralysis (THPP) is an endocrine emergency marked by recurrent attacks of muscle weakness associated with hypokalemia and thyrotoxicosis. Asiatic male patients are most often affected. On the other hand, African descents rarely present this disease. The case described shows an afrodescendant patient with hypokalemia and tetraparesis, whose diagnosis of hyperthyroidism was considered during this crisis. The THPP, although rare, is potentially lethal. Therefore, in cases of flaccid paresis crisis this diagnosis should always be considered, especially if associated with hypokalemia. In this situation, if no previous diagnosis of hyperthyroidism, this should also be regarded. PMID:25372590

  2. Regularization Paths for Generalized Linear Models via Coordinate Descent

    PubMed Central

    Friedman, Jerome; Hastie, Trevor; Tibshirani, Rob

    2010-01-01

    We develop fast algorithms for estimation of generalized linear models with convex penalties. The models include linear regression, two-class logistic regression, and multinomial regression problems while the penalties include ?1 (the lasso), ?2 (ridge regression) and mixtures of the two (the elastic net). The algorithms use cyclical coordinate descent, computed along a regularization path. The methods can handle large problems and can also deal efficiently with sparse features. In comparative timings we find that the new algorithms are considerably faster than competing methods. PMID:20808728

  3. Shuttle program: OFT ascent/descent ancillary data requirements document

    NASA Technical Reports Server (NTRS)

    Bond, A. C., Jr.; Knoedler, J.

    1980-01-01

    Requirements are presented for the ascent/descent (A/D) navigation and attitude-dependent ancillary data products to be generated for the space shuttle orbiter in support of the orbital flight test (OFT) flight test requirements, MPAD guidance and navigation performance assessment, and the mission evaluation team. The A/D ancillary data support for OFT mission evaluation activities is confined to providing postflight position, velocity, attitude, and associated navigation and attitude derived parameters for the Orbiter over particular flight phases and time intervals.

  4. Graham Greene's use of the christian concept of descent

    E-print Network

    Love, Frances Ann C

    1969-01-01

    &gonist. . , Sarah i~ilies and K!aurice . 8 ndrix, undergo the Dark liight of the Soul. Through her descent into ihc sufi'ering of both the passive night of sense and o:! spirit, Sarah '. =. wholly purified. , achieving unior! with God and becoming a saint... supplied. once and for all with a subjeot. '" 11 Doyitis believes that "what Greene does is to make 10, , '. Ihe Eos!-, C'!ildhood and Other I ~ssa s (IJew York, 1o~q~) n. 6$. 11 Faith ", ud . &'iction! Creative process in Greene a!!d ilgwu. riac (l...

  5. Successfull Management of a Life Threatening Cerebellar Haemorrhage Following Spine Surgery - A Case Report -

    PubMed Central

    Belaďd, Hayat; Aldea, Sorin

    2009-01-01

    Cerebellar haemorrhages are rare life-threatening complications following spine surgery that present challenges for their diagnostic and their therapeutic management. Their patho-physiology remains unclear. We report a case of a life-threatening cerebellar haemorrhage secondary to an occult dural tear following a planned L5-S1 laminectomy. The patient was treated with emergent external ventriculostomy following by a posterior fossa decompressive craniectomy. Cerebellar haemorrhages have to be suspected systematically when unexpected neurological signs occur after spine surgery since their rapid management lead to favourable outcomes. The present imaging findings allow us proposing that cerebellar haemorrhages result primarily from superior cerebellar venous stretching and tearing, and that cerebellar infarction and swelling occur secondarily. PMID:20404944

  6. Observations in five cases of spontaneous cerebellar hemorrhage

    PubMed Central

    Abud-Ortega, A. F.; Rajput, A.; Rozdilsky, B.

    1972-01-01

    Five cases of spontaneous intracerebellar hemorrhage are reported. Three had a vascular malformation and two had mild hypertension. The presenting symptom was sudden headache followed by nausea and vomiting. Signs of brain stem dysfunction without prominent cerebellar deficit were the commonest feature. Meningeal involvement was present in the majority of cases. Unsuspected sudden death can occur. It is suggested that patients below the age of 30 who present with sudden headache followed by brain stem dysfunction with or without a subarachnoid hemorrhage, and patients over the age of 45 who present this picture along with subarachnoid hemorrhage should be investigated urgently with contrast studies for possible cerebellar hemorrhage. ImagesFIG. 1FIG. 2FIG. 3FIG. 4 PMID:5009036

  7. Cerebellar Cognitive Affective Syndrome Presented as Severe Borderline Personality Disorder

    PubMed Central

    Pesic, Danilo; Peljto, Amir; Lukic, Biljana; Milovanovic, Maja; Svetozarevic, Snezana; Lecic Tosevski, Dusica

    2014-01-01

    An increasing number of findings confirm the significance of cerebellum in affecting regulation and early learning. Most consistent findings refer to association of congenital vermis anomalies with deficits in nonmotor functions of cerebellum. In this paper we presented a young woman who was treated since sixteen years of age for polysubstance abuse, affective instability, and self-harming who was later diagnosed with borderline personality disorder. Since the neurological and neuropsychological reports pointed to signs of cerebellar dysfunction and dysexecutive syndrome, we performed magnetic resonance imaging of brain which demonstrated partially developed vermis and rhombencephalosynapsis. These findings match the description of cerebellar cognitive affective syndrome and show an overlap with clinical manifestations of borderline personality disorder. PMID:24715924

  8. Cerebellar learning distinguishes inflammatory neuropathy with and without tremor

    PubMed Central

    Schwingenschuh, Petra; Saifee, Tabish A.; Katschnig-Winter, Petra; Reilly, Mary M.; Lunn, Michael P.; Manji, Hadi; Aguirregomozcorta, Maria; Schmidt, Reinhold; Bhatia, Kailash P.; Rothwell, John C.

    2013-01-01

    Objectives: This study aims to investigate if patients with inflammatory neuropathies and tremor have evidence of dysfunction in the cerebellum and interactions in sensorimotor cortex compared to nontremulous patients and healthy controls. Methods: A prospective data collection study investigating patients with inflammatory neuropathy and tremor, patients with inflammatory neuropathy without tremor, and healthy controls on a test of cerebellar associative learning (eyeblink classical conditioning), a test of sensorimotor integration (short afferent inhibition), and a test of associative plasticity (paired associative stimulation). We also recorded tremor in the arms using accelerometry and surface EMG. Results: We found impaired responses to eyeblink classical conditioning and paired associative stimulation in patients with neuropathy and tremor compared with neuropathy patients without tremor and healthy controls. Short afferent inhibition was normal in all groups. Conclusions: Our data strongly suggest impairment of cerebellar function is linked to the production of tremor in patients with inflammatory neuropathy. PMID:23596070

  9. Cognitive and emotional sequelae of cerebellar infarct: a case report.

    PubMed

    Greve, K W; Stanford, M S; Sutton, C; Foundas, A L

    1999-07-01

    The cerebellum has long been the subject of scientific investigation, but its role in nonmotor functions has only recently begun to receive serious consideration. Despite the growing literature linking the cerebellum to nonmotor/cognitive functions in humans, some controversy remains concerning the cerebellum's role in these processes. We present a patient who developed both specific language processing and verbal memory deficits and emotional changes in the context of normal intelligence following a bilateral cerebellar ischemic stroke. Despite having multiple localized cerebellar lesions, this patient had no significant motor problems, nor was there radiological evidence of focal forebrain lesions to which the cognitive and emotional effects might be attributed. The role of the cerebellum in cognition and the relevance of cerebellum-associated cognitive/emotional dysfunction to the practicing clinician are discussed. PMID:14590587

  10. Cerebellar gangliocytoma presenting with hemifacial spasms: clinical report, literature review and possible mechanisms

    Microsoft Academic Search

    K. Minkin; C. Tzekov; E. Naydenov; I. Ivanov; O. Kulev; K. Romansky; V. Busarsky

    2008-01-01

    Summary  Cerebellar lesions have classically been considered not to cause epilepsy. However, previous reports have attributed seizures,\\u000a beginning as hemifacial spasms to lesions of the cerebellar peduncles. We report an example of paroxysmal facial contractions\\u000a associated with a cerebellar gangliocytoma. The seizures began on the first day of life and consisted of paroxysmal contractions\\u000a involving the left orbicularis oculi, often the

  11. A comprehensive assessment of cerebellar damage in multiple sclerosis using diffusion tractography and volumetric analysis

    PubMed Central

    Anderson, VM; Wheeler-Kingshott, CAM; Abdel-Aziz, K; Miller, DH; Toosy, A; Thompson, AJ; Ciccarelli, O

    2011-01-01

    Background: White matter (WM) and grey matter (GM) brain damage in multiple sclerosis (MS) is widespread, but the extent of cerebellar involvement and impact on disability needs to be clarified. Objective: This study aimed to assess cerebellar WM and GM atrophy and the degree of fibre coherence in the main cerebellar connections, and their contribution to disability in relapsing–remitting MS (RRMS) and primary progressive MS (PPMS). Methods: Fourteen patients with RRMS, 12 patients with PPMS and 16 healthy controls were recruited. Cerebellar WM and GM volumes and tractography-derived measures from the middle and superior cerebellar peduncles, including fractional anisotropy (FA), mean diffusivity (MD), and directional diffusivities, were quantified from magnetic resonance imaging (MRI). Patients were assessed on clinical scores, including the MS Functional Composite score subtests. Linear regression models were used to compare imaging measures between 12 RRMS, 11 PPMS and 16 controls, and investigate their association with clinical scores. Results: Patients with PPMS showed reduced FA and increased radial diffusivity in the middle cerebellar peduncle compared with controls and patients with RRMS. In PPMS, lower cerebellar WM volume was associated with worse performance on the upper limb test. In the same patient group, we found significant relationships between superior cerebellar peduncle FA and upper limb function, and between superior cerebellar peduncle FA, MD and radial diffusivity and speed of walking. Conclusion: These findings indicate reduced fibre coherence in the main cerebellar connections, and link damage in the whole cerebellar WM, and, in particular, in the superior cerebellar peduncle, to motor deficit in PPMS. PMID:21511688

  12. Electrophysiological monitoring of injury progression in the rat cerebellar cortex

    PubMed Central

    Ordek, Gokhan; Proddutur, Archana; Santhakumar, Vijayalakshmi; Pfister, Bryan J.; Sahin, Mesut

    2014-01-01

    The changes of excitability in affected neural networks can be used as a marker to study the temporal course of traumatic brain injury (TBI). The cerebellum is an ideal platform to study brain injury mechanisms at the network level using the electrophysiological methods. Within its crystalline morphology, the cerebellar cortex contains highly organized topographical subunits that are defined by two main inputs, the climbing (CFs) and mossy fibers (MFs). Here we demonstrate the use of cerebellar evoked potentials (EPs) mediated through these afferent systems for monitoring the injury progression in a rat model of fluid percussion injury (FPI). A mechanical tap on the dorsal hand was used as a stimulus, and EPs were recorded from the paramedian lobule (PML) of the posterior cerebellum via multi-electrode arrays (MEAs). Post-injury evoked response amplitudes (EPAs) were analyzed on a daily basis for 1 week and compared with pre-injury values. We found a trend of consistently decreasing EPAs in all nine animals, losing as much as 72 ± 4% of baseline amplitudes measured before the injury. Notably, our results highlighted two particular time windows; the first 24 h of injury in the acute period and day-3 to day-7 in the delayed period where the largest drops (~50% and 24%) were observed in the EPAs. In addition, cross-correlations of spontaneous signals between electrode pairs declined (from 0.47 ± 0.1 to 0.35 ± 0.04, p < 0.001) along with the EPAs throughout the week of injury. In support of the electrophysiological findings, immunohistochemical analysis at day-7 post-injury showed detectable Purkinje cell loss at low FPI pressures and more with the largest pressures used. Our results suggest that sensory evoked potentials (SEPs) recorded from the cerebellar surface can be a useful technique to monitor the course of cerebellar injury and identify the phases of injury progression even at mild levels. PMID:25346664

  13. New dynamics in cerebellar Purkinje cells: torus canards.

    PubMed

    Kramer, Mark A; Traub, Roger D; Kopell, Nancy J

    2008-08-01

    We describe a transition from bursting to rapid spiking in a reduced mathematical model of a cerebellar Purkinje cell. We perform a slow-fast analysis of the system and find that-after a saddle node bifurcation of limit cycles-the full model dynamics temporarily follow a repelling branch of limit cycles. We propose that the system exhibits a dynamical phenomenon new to realistic, biophysical applications: torus canards. PMID:18764509

  14. Calcium signalling in granule neurones studied in cerebellar slices

    Microsoft Academic Search

    Sergej Kirischuk; Nana Voitenko; Platon Kostyuk; Alexej Verkhratsky

    1996-01-01

    The cytoplasmic free calcium concentration ([Ca2+i) was studied in Fura-2\\/AM loaded granule neurones in acutely prepared cerebellar slices isolated from neonatal (6 days old) and adult (30 days old) mice. Bath application of elevated (10–50 mM) KCl-containing extracellular solutions evoked [Ca2+]i rise which was dependent on extracellular Ca2+. The K+-induced [Ca2+]i elevation was inhibited to different extends by verapamil, nickel

  15. Altered corticomotor-cerebellar integrity in young ataxia telangiectasia patients.

    PubMed

    Sahama, Ishani; Sinclair, Kate; Fiori, Simona; Pannek, Kerstin; Lavin, Martin; Rose, Stephen

    2014-09-01

    Magnetic resonance imaging (MRI) research in identifying altered brain structure and function in ataxia-telangiectasia, an autosomal recessive neurodegenerative disorder, is limited. Diffusion-weighted MRI were obtained from 11 ataxia telangiectasia patients (age range, 7-22 years; mean, 12 years) and 11 typically developing age-matched participants (age range, 8-23 years; mean, 13 years). Gray matter volume alterations in patients were compared with those of healthy controls using voxel-based morphometry, whereas tract-based spatial statistics was employed to elucidate white matter microstructure differences between groups. White matter microstructure was probed using quantitative fractional anisotropy and mean diffusivity measures. Reduced gray matter volume in both cerebellar hemispheres and in the precentral-postcentral gyrus in the left cerebral hemisphere was observed in ataxia telangiectasia patients compared with controls (P?cerebellar hemispheres, anterior/posterior horns of the medulla, cerebral peduncles, and internal capsule white matter, particularly in the left posterior limb of the internal capsule and corona radiata in the left cerebral hemisphere, was observed in patients compared with controls (P?cerebellar hemisphere and the white matter of the superior lobule of the right cerebellar hemisphere (P?

  16. Imaging Spectrum of Cerebellar Pathologies: A Pictorial Essay

    PubMed Central

    Arora, Richa

    2015-01-01

    Summary The cerebellum is a crucial structure of hindbrain which helps in maintaining motor tone, posture, gait and also coordinates skilled voluntary movements including eye movements. Cerebellar abnormalities have different spectrum, presenting symptoms and prognosis as compared to supratentorial structures and brainstem. This article intends to review the various pathological processes involving the cerebellum along with their imaging features on MR, which are must to know for all radiologists, neurologists and neurosurgeons for their prompt diagnosis and management. PMID:25806100

  17. Endogenous cerebellar neurogenesis in adult mice with progressive ataxia

    PubMed Central

    Kumar, Manoj; Csaba, Zsolt; Peineau, Stéphane; Srivastava, Rupali; Rasika, Sowmyalakshmi; Mani, Shyamala; Gressens, Pierre; El Ghouzzi, Vincent

    2014-01-01

    Objective Transplanting exogenous neuronal progenitors to replace damaged neurons in the adult brain following injury or neurodegenerative disorders and achieve functional amelioration is a realistic goal. However, studies so far have rarely taken into consideration the preexisting inflammation triggered by the disease process that could hamper the effectiveness of transplanted cells. Here, we examined the fate and long-term consequences of human cerebellar granule neuron precursors (GNP) transplanted into the cerebellum of Harlequin mice, an adult model of progressive cerebellar degeneration with early-onset microgliosis. Methods Human embryonic stem cell-derived progenitors expressing Atoh1, a transcription factor key to GNP specification, were generated in vitro and stereotaxically transplanted into the cerebellum of preataxic Harlequin mice. The histological and functional impact of these transplants was followed using immunolabeling and Rotarod analysis. Results Although transplanted GNPs did not survive beyond a few weeks, they triggered the proliferation of endogenous nestin-positive precursors in the leptomeninges that crossed the molecular layer and differentiated into mature neurons. These phenomena were accompanied by the preservation of the granule and Purkinje cell layers and delayed ataxic changes. In vitro neurosphere generation confirmed the enhanced neurogenic potential of the cerebellar leptomeninges of Harlequin mice transplanted with exogenous GNPs. Interpretation The cerebellar leptomeninges of adult mice contain an endogenous neurogenic niche that can be stimulated to yield mature neurons from an as-yet unidentified population of progenitors. The transplantation of human GNPs not only stimulates this neurogenesis, but, despite the potentially hostile environment, leads to neuroprotection and functional amelioration. PMID:25574472

  18. Does squatting reduce pelvic floor descent during defaecation?

    PubMed

    Lam, T C; Islam, N; Lubowski, D Z; King, D W

    1993-03-01

    Neurogenic faecal and urinary incontinence result from a stretch-induced injury to the pelvic nerves, from difficult childbirth or from chronic straining at stool. It has been suggested that the condition occurs less frequently in societies where the squatting position is used during defaecation, and that squatting may minimize pelvic floor descent. This is a prospective study which evaluates the position of the pelvic floor during defaecation straining in 52 patients. The position of the perineum was measured at rest and during maximal defaecation straining using a perineometer, with the patient in the left lateral, sitting and squatting positions. There was a significant difference in the position of the perineum at rest and on straining between the left lateral position and both the sitting and squatting positions. However, there was no significant difference at rest or on straining between the sitting and squatting positions. These results show that squatting does not reduce pelvic floor descent during defaecation straining, and imply that squatting would not help reverse stretch-induced pudendal nerve damage. PMID:8311789

  19. Mars Science Laboratory Entry Descent and Landing Simulation Using DSENDS

    NASA Technical Reports Server (NTRS)

    Burkhart, P. Daniel; Casoliva, Jordi; Balaram, Bob

    2013-01-01

    The most recent planetary science mission to Mars is Mars Science Laboratory (MSL) with the Curiosity rover, launched November 26, 2011 and landed at Gale Crater on August 6, 2012. This spacecraft was the first use at Mars of a complete closed-loop Guidance Navigation and Control (GN&C) system, including guided entry with a lifting body that greatly reduces dispersions during the Entry, Descent and Landing (EDL) phase to achieve a 25 km x 20 km landing error relative to the selected Gale Crater landing target. In order to confirm meeting the above landing criteria, high-fidelity simulation of the EDL phase is required. The tool used for 6DOF EDL trajectory verification analysis is Dynamics Simulator for Entry, Descent and Surface landing (DSENDS), which is a high-fidelity simulation tool from JPLs Dynamics and Real-Time Simulation Laboratory for the development, test and operations of aero-flight vehicles. DSENDS inherent capability is augmented for MSL with project-specific models of atmosphere, aerodynamics, sensors and thrusters along with GN&C flight software to enable high-fidelity trajectory simulation. This paper will present the model integration and independent verification experience of the JPL EDL trajectory analysis team.

  20. Controller evaluations of the descent advisor automation aid

    NASA Technical Reports Server (NTRS)

    Tobias, Leonard; Volckers, Uwe; Erzberger, Heinz

    1989-01-01

    An automation aid to assist air traffic controllers in efficiently spacing traffic and meeting arrival times at a fix has been developed at NASA Ames Research Center. The automation aid, referred to as the descent advisor (DA), is based on accurate models of aircraft performance and weather conditions. The DA generates suggested clearances, including both top-of-descent point and speed profile data, for one or more aircraft in order to achieve specific time or distance separation objectives. The DA algorithm is interfaced with a mouse-based, menu-driven controller display that allows the air traffic controller to interactively use its accurate predictive capability to resolve conflicts and issue advisories to arrival aircraft. This paper focuses on operational issues concerning the utilization of the DA, specifically, how the DA can be used for prediction, intrail spacing, and metering. In order to evaluate the DA, a real time simulation was conducted using both current and retired controller subjects. Controllers operated in teams of two, as they do in the present environment; issues of training and team interaction will be discussed. Evaluations by controllers indicated considerable enthusiasm for the DA aid, and provided specific recommendations for using the tool effectively.

  1. Mars Exploration Rover Terminal Descent Mission Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Raiszadeh, Behzad; Queen, Eric M.

    2004-01-01

    Because of NASA's added reliance on simulation for successful interplanetary missions, the MER mission has developed a detailed EDL trajectory modeling and simulation. This paper summarizes how the MER EDL sequence of events are modeled, verification of the methods used, and the inputs. This simulation is built upon a multibody parachute trajectory simulation tool that has been developed in POST I1 that accurately simulates the trajectory of multiple vehicles in flight with interacting forces. In this model the parachute and the suspended bodies are treated as 6 Degree-of-Freedom (6 DOF) bodies. The terminal descent phase of the mission consists of several Entry, Descent, Landing (EDL) events, such as parachute deployment, heatshield separation, deployment of the lander from the backshell, deployment of the airbags, RAD firings, TIRS firings, etc. For an accurate, reliable simulation these events need to be modeled seamlessly and robustly so that the simulations will remain numerically stable during Monte-Carlo simulations. This paper also summarizes how the events have been modeled, the numerical issues, and modeling challenges.

  2. Size of Error Affects Cerebellar Contributions to Motor Learning

    PubMed Central

    Bastian, Amy J.; Shadmehr, Reza

    2010-01-01

    Small errors may affect the process of learning in a fundamentally different way than large errors. For example, adapting reaching movements in response to a small perturbation produces generalization patterns that are different from large perturbations. Are distinct neural mechanisms engaged in response to large versus small errors? Here, we examined the motor learning process in patients with severe degeneration of the cerebellum. Consistent with earlier reports, we found that the patients were profoundly impaired in adapting their motor commands during reaching movements in response to large, sudden perturbations. However, when the same magnitude perturbation was imposed gradually over many trials, the patients showed marked improvements, uncovering a latent ability to learn from errors. On sudden removal of the perturbation, the patients exhibited aftereffects that persisted much longer than did those in healthy controls. That is, despite cerebellar damage, the brain maintained the ability to learn from small errors and the motor memory that resulted from this learning was strongly resistant to change. Of note was the fact that on completion of learning, the motor output of the cerebellar patients remained distinct from healthy controls in terms of its temporal characteristics. Therefore cerebellar degeneration impaired the ability to learn from large-magnitude errors, but had a lesser impact on learning from small errors. The neural basis of motor learning in response to small and large errors appears to be distinct. PMID:20164398

  3. Limited regional cerebellar dysfunction induces focal dystonia in mice

    PubMed Central

    Raike, Robert S.; Pizoli, Carolyn E.; Weisz, Catherine; van den Maagdenberg, Arn M. J.M.; Jinnah, H.A.; Hess, Ellen J.

    2012-01-01

    Dystonia is a complex neurological syndrome broadly characterized by involuntary twisting movements and abnormal postures. The anatomical distribution of the motor symptoms varies among dystonia patients and can range from focal, involving an isolated part of the body, to generalized, involving many body parts. Functional imaging studies of both focal and generalized dystonia in humans often implicate the cerebellum suggesting that similar pathological processes may underlie both. To test this, we exploited tools developed in mice to generate animals with gradients of cerebellar dysfunction. By using conditional genetics to regionally limit cerebellar dysfunction, we found that abnormalities restricted to Purkinje cells were sufficient to cause dystonia. In fact, the extent of cerebellar dysfunction determined the extent of abnormal movements. Dysfunction of the entire cerebellum caused abnormal postures of many body parts, resembling generalized dystonia. More limited regions of dysfunction that were created by electrical stimulation or conditional genetic manipulations produced abnormal movements in an isolated body part, resembling focal dystonia. Overall, these results suggest that focal and generalized dystonias may arise through similar mechanisms and therefore may be approached with similar therapeutic strategies. PMID:22850483

  4. Size of error affects cerebellar contributions to motor learning.

    PubMed

    Criscimagna-Hemminger, Sarah E; Bastian, Amy J; Shadmehr, Reza

    2010-04-01

    Small errors may affect the process of learning in a fundamentally different way than large errors. For example, adapting reaching movements in response to a small perturbation produces generalization patterns that are different from large perturbations. Are distinct neural mechanisms engaged in response to large versus small errors? Here, we examined the motor learning process in patients with severe degeneration of the cerebellum. Consistent with earlier reports, we found that the patients were profoundly impaired in adapting their motor commands during reaching movements in response to large, sudden perturbations. However, when the same magnitude perturbation was imposed gradually over many trials, the patients showed marked improvements, uncovering a latent ability to learn from errors. On sudden removal of the perturbation, the patients exhibited aftereffects that persisted much longer than did those in healthy controls. That is, despite cerebellar damage, the brain maintained the ability to learn from small errors and the motor memory that resulted from this learning was strongly resistant to change. Of note was the fact that on completion of learning, the motor output of the cerebellar patients remained distinct from healthy controls in terms of its temporal characteristics. Therefore cerebellar degeneration impaired the ability to learn from large-magnitude errors, but had a lesser impact on learning from small errors. The neural basis of motor learning in response to small and large errors appears to be distinct. PMID:20164398

  5. Cerebellar ataxia impairs modulation of arm stiffness during postural maintenance

    PubMed Central

    Gibo, Tricia L.; Bastian, Amy J.

    2013-01-01

    Impedance control enables humans to effectively interact with their environment during postural and movement tasks, adjusting the mechanical behavior of their limbs to account for instability. Previous work has shown that people are able to selectively modulate the end-point stiffness of their arms, adjusting for varying directions of environmental disturbances. Behavioral studies also suggest that separate controllers are used for impedance modulation versus joint torque coordination. Here we tested whether people with cerebellar damage have deficits in impedance control. It is known that these individuals have poor motor coordination, which has typically been attributed to deficits in joint torque control. Subjects performed a static postural maintenance task with two different types of directional force perturbations. On average, patients with cerebellar ataxia modified stiffness differentially for the two perturbation conditions, although significantly less than age-matched control subjects. Thus cerebellar damage may impair the ability to modulate arm impedance. Surprisingly, the patients' intact ability to generally alter their limb stiffness during the postural task (albeit less than age-matched control subjects) improved their movement performance in a subsequent tracing task. The transfer of stiffness control from the static to the movement task may be a strategy that can be used by patients to compensate for their motor deficits. PMID:23843434

  6. Cerebellar vermis H? receptors mediate fear memory consolidation in mice.

    PubMed

    Gianlorenço, A C L; Riboldi, A M; Silva-Marques, B; Mattioli, R

    2015-02-01

    Histaminergic fibers are present in the molecular and granular layers of the cerebellum and have a high density in the vermis and flocullus. Evidence supports that the cerebellar histaminergic system is involved in memory consolidation. Our recent study showed that histamine injections facilitate the retention of an inhibitory avoidance task, which was abolished by pretreatment with an H2 receptor antagonist. In the present study, we investigated the effects of intracerebellar post training injections of H1 and H2 receptor antagonists as well as the selective H2 receptor agonist on fear memory consolidation. The cerebellar vermi of male mice were implanted with guide cannulae, and after three days of recovery, the inhibitory avoidance test was performed. Immediately after a training session, animals received a microinjection of the following histaminergic drugs: experiment 1, saline or chlorpheniramine (0.016, 0.052 or 0.16 nmol); experiment 2, saline or ranitidine (0.57, 2.85 or 5.07 nmol); and experiment 3, saline or dimaprit (1, 2 or 4 nmol). Twenty-four hours later, a retention test was performed. The data were analyzed using one-way analysis of variance (ANOVA) and Duncan's tests. Animals microinjected with chlorpheniramine did not show any behavioral effects at the doses that we used. Intra-cerebellar injection of the H2 receptor antagonist ranitidine inhibited, while the selective H2 receptor agonist dimaprit facilitated, memory consolidation, suggesting that H2 receptors mediate memory consolidation in the inhibitory avoidance task in mice. PMID:25524412

  7. Redefining the cerebellar cortex as an assembly of non-uniform Purkinje cell microcircuits.

    PubMed

    Cerminara, Nadia L; Lang, Eric J; Sillitoe, Roy V; Apps, Richard

    2015-02-01

    The adult mammalian cerebellar cortex is generally assumed to have a uniform cytoarchitecture. Differences in cerebellar function are thought to arise primarily through distinct patterns of input and output connectivity rather than as a result of variations in cortical microcircuitry. However, evidence from anatomical, physiological and genetic studies is increasingly challenging this orthodoxy, and there are now various lines of evidence indicating that the cerebellar cortex is not uniform. Here, we develop the hypothesis that regional differences in properties of cerebellar cortical microcircuits lead to important differences in information processing. PMID:25601779

  8. Recovery of biological motion perception and network plasticity after cerebellar tumor removal.

    PubMed

    Sokolov, Arseny A; Erb, Michael; Grodd, Wolfgang; Tatagiba, Marcos S; Frackowiak, Richard S J; Pavlova, Marina A

    2014-10-01

    Visual perception of body motion is vital for everyday activities such as social interaction, motor learning or car driving. Tumors to the left lateral cerebellum impair visual perception of body motion. However, compensatory potential after cerebellar damage and underlying neural mechanisms remain unknown. In the present study, visual sensitivity to point-light body motion was psychophysically assessed in patient SL with dysplastic gangliocytoma (Lhermitte-Duclos disease) to the left cerebellum before and after neurosurgery, and in a group of healthy matched controls. Brain activity during processing of body motion was assessed by functional magnetic resonance imaging (MRI). Alterations in underlying cerebro-cerebellar circuitry were studied by psychophysiological interaction (PPI) analysis. Visual sensitivity to body motion in patient SL before neurosurgery was substantially lower than in controls, with significant improvement after neurosurgery. Functional MRI in patient SL revealed a similar pattern of cerebellar activation during biological motion processing as in healthy participants, but located more medially, in the left cerebellar lobules III and IX. As in normalcy, PPI analysis showed cerebellar communication with a region in the superior temporal sulcus, but located more anteriorly. The findings demonstrate a potential for recovery of visual body motion processing after cerebellar damage, likely mediated by topographic shifts within the corresponding cerebro-cerebellar circuitry induced by cerebellar reorganization. The outcome is of importance for further understanding of cerebellar plasticity and neural circuits underpinning visual social cognition. PMID:25017648

  9. Cerebellar Output in Zebrafish: An Analysis of Spatial Patterns and Topography in Eurydendroid Cell Projections

    PubMed Central

    Heap, Lucy A.; Goh, Chi Ching; Kassahn, Karin S.; Scott, Ethan K.

    2013-01-01

    The cerebellum is a brain region responsible for motor coordination and for refining motor programs. While a great deal is known about the structure and connectivity of the mammalian cerebellum, fundamental questions regarding its function in behavior remain unanswered. Recently, the zebrafish has emerged as a useful model organism for cerebellar studies, owing in part to the similarity in cerebellar circuits between zebrafish and mammals. While the cell types composing their cerebellar cortical circuits are generally conserved with mammals, zebrafish lack deep cerebellar nuclei, and instead a majority of cerebellar output comes from a single type of neuron: the eurydendroid cell. To describe spatial patterns of cerebellar output in zebrafish, we have used genetic techniques to label and trace eurydendroid cells individually and en masse. We have found that cerebellar output targets the thalamus and optic tectum, and have confirmed the presence of pre-synaptic terminals from eurydendroid cells in these structures using a synaptically targeted GFP. By observing individual eurydendroid cells, we have shown that different medial-lateral regions of the cerebellum have eurydendroid cells projecting to different targets. Finally, we found topographic organization in the connectivity between the cerebellum and the optic tectum, where more medial eurydendroid cells project to the rostral tectum while lateral cells project to the caudal tectum. These findings indicate that there is spatial logic underpinning cerebellar output in zebrafish with likely implications for cerebellar function. PMID:23554587

  10. Isoniazid-induced reduction in GABAergic neurotransmission alters the function of the cerebellar cortical circuit.

    PubMed

    Carta, M; Murru, L; Barabino, E; Talani, G; Sanna, E; Biggio, G

    2008-06-23

    The cerebellar cortex contributes to the control of movement, coordination, and certain cognitive functions. The cerebellar network is composed of five different types of neurons that are wired together in a repetitive module. Given that four of these five neurons synthesize and release GABA, this inhibitory neurotransmitter plays a central role in regulation of the excitability and correct functioning of the cerebellar cortex. We have now used isoniazid, an inhibitor of glutamic acid decarboxylase, the enzyme responsible for the synthesis of GABA, to evaluate the contribution of GABAergic transmission in different types of cerebellar cortical neurons to the functioning of the cerebellar circuit. Parasagittal cerebellar slices were prepared from 28- to 40-day-old male rats and were subjected to patch-clamp recording in the voltage- or current-clamp mode. Exposure of the tissue slices to isoniazid (10 mM) resulted in a decrease in the level of GABAergic transmission in Purkinje cells and a consequent increase in the firing rate of spontaneous action potentials that was apparent after 40 min. In granule neurons, isoniazid reduced both tonic and phasic GABAergic currents and thereby altered the flow of information across the cerebellar cortex. Our data support the notion that the amount of GABA at the synaptic level is a major determinant of the excitability of the cerebellar cortex, and they suggest that isoniazid may be a useful tool with which to study the function of the cerebellar network. PMID:18456415

  11. Applying Online Gradient Descent Search to Genetic Programming for Object Recognition

    E-print Network

    Fernandez, Thomas

    Applying Online Gradient Descent Search to Genetic Programming for Object Recognition Will Smart to the use of gradi- ent descent search in genetic programming (GP) for object classification problems to the GP mechanism and is embedded into the genetic beam search, which allows the evolutionary learning

  12. The Yearly Variation in Fall-Winter Arctic Winter Vortex Descent

    NASA Technical Reports Server (NTRS)

    Schoeberl, Mark R.; Newman, Paul A.

    1999-01-01

    Using the change in HALOE methane profiles from early September to late March, we have estimated the minimum amount of diabatic descent within the polar which takes place during Arctic winter. The year to year variations are a result in the year to year variations in stratospheric wave activity which (1) modify the temperature of the vortex and thus the cooling rate; (2) reduce the apparent descent by mixing high amounts of methane into the vortex. The peak descent amounts from HALOE methane vary from l0km -14km near the arrival altitude of 25 km. Using a diabatic trajectory calculation, we compare forward and backward trajectories over the course of the winter using UKMO assimilated stratospheric data. The forward calculation agrees fairly well with the observed descent. The backward calculation appears to be unable to produce the observed amount of descent, but this is only an apparent effect due to the density decrease in parcels with altitude. Finally we show the results for unmixed descent experiments - where the parcels are fixed in latitude and longitude and allowed to descend based on the local cooling rate. Unmixed descent is found to always exceed mixed descent, because when normal parcel motion is included, the path average cooling is always less than the cooling at a fixed polar point.

  13. Proving Mordell-Weil: A Descent in Three Parts A Senior Thesis Of

    E-print Network

    Stein, William

    3 #12;Introductions In 1659, Pierre de Fermat wrote to Christiaan Huygens claiming to have on elliptic curves. In this thesis, we examine three of these moments: (1) Pierre de Fermat's proof. Descent 1: Fermat's Infinite Descent 40 Conclusion 43 Appendix A. Cohomology of Groups 45 Bibliography 48

  14. Engine Placement for Manned Descent at Mars Considering Single Engine Failures

    E-print Network

    . Vehicles large enough to support humans on the flight to Mars and land them safely on the surfaceEngine Placement for Manned Descent at Mars Considering Single Engine Failures by STEPHEN P. YORK B;3 Engine Placement for Manned Descent at Mars Considering Single Engine Failures by STEPHEN P. YORK

  15. A dynamic continuous descent approach methodology for low noise and emission

    Microsoft Academic Search

    S. Alam; M. H. Nguyen; H. A. Abbass; C. Lokan; M. Ellejmi; S. Kirby

    2010-01-01

    Continuous Descent Approaches (CDAs) can significantly reduce fuel burn and noise impact by keeping arriving aircraft at their cruise altitude for longer than during conventional approaches(to descend as late as possible)and then having them make a continuous descent to the runway at near idle thrust with no level flight segments. The CDA procedures are fixed routes that are vertically optimized.

  16. A block-based gradient descent search algorithm for block motion estimation in video coding

    Microsoft Academic Search

    Lurng-Kuo Liu; E. Feig

    1996-01-01

    A block-based gradient descent search (BBGDS) algorithm is proposed in this paper to perform block motion estimation in video coding. The BBGDS evaluates the values of a given objective function starting from a small centralized checking block. The minimum within the checking block is found, and the gradient descent direction where the minimum is expected to lie is used to

  17. Miniature coherent velocimeter and altimeter (MCVA) for terminal descent control on lunar and planetary landers

    NASA Technical Reports Server (NTRS)

    Chang, Dan; Cardell, Greg; Szwaykowski, Piotr; Shaffat, Syed T.; Meras, Patrick

    2005-01-01

    While the overall architecture of an Entry Descent and Landing (EDL) system may vary depending on specific mission requirementsw, measurements of the rate vector with respect to the surface is a primary requirement for the Terminal Descent Control (TDC) phase of any controlled lander.

  18. Evidence of pudendal neuropathy in patients with perineal descent and chronic straining at stool

    Microsoft Academic Search

    E S Kiff; P R Barnes; M Swash

    1984-01-01

    In 17 women with chronic constipation, and abnormal perineal descent on straining at stool, there was more severe neurogenic damage to the external anal sphincter muscle and to its pudendal innervation in those patients with a long history than in those with a short history. These results suggest that recurrent trauma to the pudendal nerves can occur during perineal descent,

  19. Prostate Cancer in Men of African Descent: Opportunities for Global Research Collaborations

    Cancer.gov

    Prostate cancer disproportionately affects men of African descent in terms of incidence, morbidity, and mortality worldwide. Significant knowledge gaps exist about the factors that predict disparities in prostate cancer incidence and outcomes between men of African descent and other ethnic or racial groups.

  20. Asynchronous Peer-to-peer Data Mining with Stochastic Gradient Descent

    E-print Network

    Jelasity, Márk

    Asynchronous Peer-to-peer Data Mining with Stochastic Gradient Descent Róbert Ormándi1 , István a stochastic gradient descent search. We demonstrate our approach by implementing the support vector machine participating nodes. Our contribution is that we propose a method based on stochastic gradient search that meets

  1. Introduction to the special issue on lesbians of African descent: contemporary perspectives.

    PubMed

    Wilson, Bianca D M; Johnson, Verlena L

    2011-01-01

    This article serves as an introduction to the special issue entitled, "Lesbians of African Descent: Contemporary Perspectives." We briefly discuss our framing of this collection as a contemporary contribution to the canon of Black lesbian writing and art, and identify themes that appear to transcend both earlier and current works of lesbians of African descent. PMID:21279896

  2. Stochastic Gradient Descent Optimization for Low Power Nano-CMOS Thermal Sensor Design

    E-print Network

    Mohanty, Saraju P.

    descent (SGD) based algorithm and is implemented using a 45 nm thermal sensor circuit as case study. Power gradient descent based (SGD) algorithm. The SGD algorithm helps to improve the optimization time and also is the presentation of a design optimization flow model, which incorporates an SGD algorithm for the optimization

  3. 14 CFR 121.333 - Supplemental oxygen for emergency descent and for first aid; turbine engine powered airplanes...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 false Supplemental oxygen for emergency descent and for first aid...Requirements § 121.333 Supplemental oxygen for emergency descent and for first aid...the certificate holder shall furnish oxygen and dispensing equipment to comply...

  4. 14 CFR 121.333 - Supplemental oxygen for emergency descent and for first aid; turbine engine powered airplanes...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 false Supplemental oxygen for emergency descent and for first aid...Requirements § 121.333 Supplemental oxygen for emergency descent and for first aid...the certificate holder shall furnish oxygen and dispensing equipment to comply...

  5. 14 CFR 121.333 - Supplemental oxygen for emergency descent and for first aid; turbine engine powered airplanes...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 false Supplemental oxygen for emergency descent and for first aid...Requirements § 121.333 Supplemental oxygen for emergency descent and for first aid...the certificate holder shall furnish oxygen and dispensing equipment to comply...

  6. 14 CFR 121.333 - Supplemental oxygen for emergency descent and for first aid; turbine engine powered airplanes...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 2011-01-01 false Supplemental oxygen for emergency descent and for first aid...Requirements § 121.333 Supplemental oxygen for emergency descent and for first aid...the certificate holder shall furnish oxygen and dispensing equipment to comply...

  7. 14 CFR 121.333 - Supplemental oxygen for emergency descent and for first aid; turbine engine powered airplanes...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...for emergency descent and for first aid; turbine engine powered airplanes with pressurized...for emergency descent and for first aid; turbine engine powered airplanes with pressurized... (a) General. When operating a turbine engine powered airplane with a...

  8. Flavoprotein imaging in the cerebellar cortex in vivo: cellular and metabolic basis and insights into cerebellar function

    NASA Astrophysics Data System (ADS)

    Gao, Wangcai; Chen, Gang; Ebner, Timothy J.

    2009-02-01

    Flavoprotein autofluorescence is an activity dependent intrinsic signal. Flavoproteins are involved in the electron transport chain and change their fluorescence according to the cellular redox state. We have been using flavoprotein autofluorescence in the cerebellum to examine properties of cerebellar circuits. Studies have also focused on understanding the cellular and metabolic origins of this intrinsic optical signal. Parallel fiber stimulation evokes a beamlike response intersected by bands of decreased fluorescence. The beam response is biphasic, with an early fluorescence increase (light phase) followed by a slower decrease (dark phase). We show this signal originates from flavoproteins as determined by its wavelength selectivity and sensitivity to blockers of the electron transport chain. Selectively blocking glutamate receptors abolished the on-beam light phase with the dark phase remaining intact. This demonstrates that the light phase is due to postsynaptic neuronal activation and suggests the dark phase is primarily due to glial activation. The bands of reduced fluorescence intersecting the beam are primarily neuronal in origin, mediated by GABAergic transmission, and due to the inhibitory action of molecular layer interneurons on Purkinje cells and the interneurons themselves. This parasagittally organized molecular layer inhibition differentially modulates the spatial pattern of cerebellar cortical activity. Flavoprotein imaging also reveals the functional architectures underlying the responses to inferior olive and peripheral whisker pad stimulation. Therefore, flavoprotein autofluorescence imaging is providing new insights into cerebellar cortical function and neurometabolic coupling.

  9. Evaluation of vertical profiles to design continuous descent approach procedure

    NASA Astrophysics Data System (ADS)

    Pradeep, Priyank

    The current research focuses on predictability, variability and operational feasibility aspect of Continuous Descent Approach (CDA), which is among the key concepts of the Next Generation Air Transportation System (NextGen). The idle-thrust CDA is a fuel economical, noise and emission abatement procedure, but requires increased separation to accommodate for variability and uncertainties in vertical and speed profiles of arriving aircraft. Although a considerable amount of researches have been devoted to the estimation of potential benefits of the CDA, only few have attempted to explain the predictability, variability and operational feasibility aspect of CDA. The analytical equations derived using flight dynamics and Base of Aircraft and Data (BADA) Total Energy Model (TEM) in this research gives insight into dependency of vertical profile of CDA on various factors like wind speed and gradient, weight, aircraft type and configuration, thrust settings, atmospheric factors (deviation from ISA (DISA), pressure and density of the air) and descent speed profile. Application of the derived equations to idle-thrust CDA gives an insight into sensitivity of its vertical profile to multiple factors. This suggests fixed geometric flight path angle (FPA) CDA has higher degree of predictability and lesser variability at the cost of non-idle and low thrust engine settings. However, with optimized design this impact can be overall minimized. The CDA simulations were performed using Future ATM Concept Evaluation Tool (FACET) based on radar-track and aircraft type data (BADA) of the real air-traffic to some of the busiest airports in the USA (ATL, SFO and New York Metroplex (JFK, EWR and LGA)). The statistical analysis of the vertical profiles of CDA shows 1) mean geometric FPAs derived from various simulated vertical profiles are consistently shallower than 3° glideslope angle and 2) high level of variability in vertical profiles of idle-thrust CDA even in absence of uncertainties in external factors. Analysis from operational feasibility perspective suggests that two key features of the performance based Flight Management System (FMS) i.e. required time of arrival (RTA) and geometric descent path would help in reduction of unpredictability associated with arrival time and vertical profile of aircraft guided by the FMS coupled with auto-pilot (AP) and auto-throttle (AT). The statistical analysis of the vertical profiles of CDA also suggests that for procedure design window type, 'AT or above' and 'AT or below' altitude and FPA constraints are more realistic and useful compared to obsolete 'AT' type altitude constraint.

  10. Description of the computations and pilot procedures for planning fuel-conservative descents with a small programmable calculator

    Microsoft Academic Search

    D. D. Vicroy; C. E. Knox

    1983-01-01

    A simplified flight management descent algorithm was developed and programmed on a small programmable calculator. It was designed to aid the pilot in planning and executing a fuel conservative descent to arrive at a metering fix at a time designated by the air traffic control system. The algorithm may also be used for planning fuel conservative descents when time is

  11. Calvin's confession of Christ's descent into hell in the context of the doctrine of redemption: an historical and hermeneutical inquiry

    Microsoft Academic Search

    Robert M. Brenton

    2005-01-01

    This thesis deals with the credibility problem of the creedal article on Christ's descent into hell, and proposes that this article of faith can be restored to credibility by accepting Calvin's confession on Christ's descent. The question of whether Calvin's interpretation of the descent as Christ's soul-suffering or redemptive agony can fill the credibility gap is answered by following a

  12. Overview of the Phoenix Entry, Descent and Landing System Architecture

    NASA Technical Reports Server (NTRS)

    Grover, Myron R., III; Cichy, Benjamin D.; Desai, Prasun N.

    2008-01-01

    NASA s Phoenix Mars Lander began its journey to Mars from Cape Canaveral, Florida in August 2007, but its journey to the launch pad began many years earlier in 1997 as NASA s Mars Surveyor Program 2001 Lander. In the intervening years, the entry, descent and landing (EDL) system architecture went through a series of changes, resulting in the system flown to the surface of Mars on May 25th, 2008. Some changes, such as entry velocity and landing site elevation, were the result of differences in mission design. Other changes, including the removal of hypersonic guidance, the reformulation of the parachute deployment algorithm, and the addition of the backshell avoidance maneuver, were driven by constant efforts to augment system robustness. An overview of the Phoenix EDL system architecture is presented along with rationales driving these architectural changes.

  13. Apollo 16 LM-11 descent propulsion system final flight evaluation

    NASA Technical Reports Server (NTRS)

    Avvenire, A. T.

    1973-01-01

    The performance of the LM-11 Descent Propulsion System during the Apollo 16 Mission was evaluated and found to be satisfactory. The average engine effective specific impulse was 0.1 second higher than predicted, but well within the predicted 1 sigma uncertainty of 0.2 seconds. The engine performance corrected to standard inlet conditions for the FTP portion of the burn at 50 seconds after ignition was as follows: thrust, 9839 lbf; specific impulse, 306.9 sec; and propellant mixture ratio, 1.592. These values are +0.34, +0.03 and +0.0 percent different, respectively, from the values reported from engine acceptance tests and were within specification limits. Several flight measurement discrepancies that existed during the flight are discussed.

  14. Transitions and transversions in evolutionary descent - An approach to understanding

    NASA Technical Reports Server (NTRS)

    Holmquist, R.

    1983-01-01

    A quantitative theoretical groundwork is presented for determining the proportions of the possible types of base substitutions observed between 12 genes sharing a common ancestor and isolated from extant species. Three methods (direct count, regression, and informational entropy maximization) are described by which conditional base substitution probabilities that determine evolutionary descent can be estimated from experimental data. These methods are utilized to study the ratio of transversions to transitions during gene divergence. The limiting ratio is directly calculated from a knowledge of the 12 conditional probabilities for each type of base substitution and from a knowledge of the equilibrium base composition of the DNAs compared. An expression is developed for this calculation. It is concluded that multiple substitutions per se do not lead to a decrease in transition differences with increasing evolutionary divergence.

  15. Mars Science Laboratory Entry, Descent, and Landing System Overview

    NASA Technical Reports Server (NTRS)

    Prakash, Ravi; Burkhart, P. Dan; Chen, Allen; Comeaux, Keith A.; Guernsey, Carl S.; Devin, M. Kipp; Mendeck, Gavin F.; Powell, Richard W.; Rivellini, Tommaso P.; San Martin, A. Miguel; Sell, Steven W.; Steltzner, Adam D.; Way, David W.

    2008-01-01

    In 2010, the Mars Science Laboratory (MSL) mission will pioneer the next generation of robotic Entry, Descent, and Landing (EDL) systems by delivering the largest and most capable rover to date to the surface of Mars. In addition to landing more mass than prior missions to Mars, MSL will offer access to regions of Mars that have been previously unreachable. The MSL EDL sequence is a result of a more stringent requirement set than any of its predecessors. Notable among these requirements is landing a 900 kg rover in a landing ellipse much smaller than that of any previous Mars lander. In meeting these requirements, MSL is extending the limits of the EDL technologies qualified by the Mars Viking, Mars Pathfinder, and Mars Exploration Rover missions.

  16. Generalized Harish-Chandra descent and applications to Gelfand pairs

    E-print Network

    Aizenbud, Avraham

    2008-01-01

    In the first part of the paper we generalize a descent technique due to Harish-Chandra to the case of a reductive group acting on a smooth affine variety both defined over arbitrary local field F of characteristic zero. Our main tool in that is Luna slice theorem. In the second part of the paper we apply this technique to symmetric pairs. In particular we prove that the pair (GL(n,C),GL(n,R)) is a Gelfand pair. We also prove that any conjugation invariant distribution on GL(n,F) is invariant with respect to transposition. For non-archimedean F the later is a classical theorem of Gelfand and Kazhdan. We use the techniques developed here in our proceeding work [AG3] where we prove an archimedean analog of the theorem on uniqueness of linear periods by H. Jacquet and S. Rallis.

  17. Y chromosome lineages in men of west African descent.

    PubMed

    Torres, Jada Benn; Doura, Menahem B; Keita, Shomarka O Y; Kittles, Rick A

    2012-01-01

    The early African experience in the Americas is marked by the transatlantic slave trade from ?1619 to 1850 and the rise of the plantation system. The origins of enslaved Africans were largely dependent on European preferences as well as the availability of potential laborers within Africa. Rice production was a key industry of many colonial South Carolina low country plantations. Accordingly, rice plantations owners within South Carolina often requested enslaved Africans from the so-called "Grain Coast" of western Africa (Senegal to Sierra Leone). Studies on the African origins of the enslaved within other regions of the Americas have been limited. To address the issue of origins of people of African descent within the Americas and understand more about the genetic heterogeneity present within Africa and the African Diaspora, we typed Y chromosome specific markers in 1,319 men consisting of 508 west and central Africans (from 12 populations), 188 Caribbeans (from 2 islands), 532 African Americans (AAs from Washington, DC and Columbia, SC), and 91 European Americans. Principal component and admixture analyses provide support for significant Grain Coast ancestry among African American men in South Carolina. AA men from DC and the Caribbean showed a closer affinity to populations from the Bight of Biafra. Furthermore, 30-40% of the paternal lineages in African descent populations in the Americas are of European ancestry. Diverse west African ancestries and sex-biased gene flow from EAs has contributed greatly to the genetic heterogeneity of African populations throughout the Americas and has significant implications for gene mapping efforts in these populations. PMID:22295064

  18. Purkinje Cell Activity in the Cerebellar Anterior Lobe after Rabbit Eyeblink Conditioning

    ERIC Educational Resources Information Center

    Green, John T.; Steinmetz, Joseph E.

    2005-01-01

    The cerebellar anterior lobe may play a critical role in the execution and proper timing of learned responses. The current study was designed to monitor Purkinje cell activity in the rabbit cerebellar anterior lobe after eyeblink conditioning, and to assess whether Purkinje cells in recording locations may project to the interpositus nucleus.…

  19. BK Channels Control Cerebellar Purkinje and Golgi Cell Rhythmicity In Vivo

    Microsoft Academic Search

    Guy Cheron; Matthias Sausbier; Ulrike Sausbier; Winfried Neuhuber; Peter Ruth; Bernard Dan; Laurent Servais; Yuan Luo

    2009-01-01

    Calcium signaling plays a central role in normal CNS functioning and dysfunction. As cerebellar Purkinje cells express the major regulatory elements of calcium control and represent the sole integrative output of the cerebellar cortex, changes in neural activity- and calcium-mediated membrane properties of these cells are expected to provide important insights into both intrinsic and network physiology of the cerebellum.

  20. Ultrastructural analysis on acetylcholinesterase localization in the cerebellar cortex of teleosts

    Microsoft Academic Search

    Antonio Contestabile; Luigi Villani; Franco Ciani

    1977-01-01

    The histochemical localization of acetylcholinesterase (AChE) was studied by electron microscopy in the cerebellar cortex of the goldfish and the catfish. The patterns of enzyme distribution show noticeable differences in the two teleost species at the level of the corresponding cerebellar structures. Among the most distinctive features in the prevailing intracellular localization of enzyme activity in the goldfish and the

  1. EFFECT OF ATRAZINE ADMINISTRATION ON SPONTANEOUS AND EVOKED CEREBELLAR ACTIVITY IN THE RAT

    Microsoft Academic Search

    MARIA VITTORIA PODDA; FRANCA DERIU; ANTONIO SOLINAS; MARIA PIERA DEMONTIS; MARIA VITTORIA VARONI; ALESSANDRO SPISSU; VITTORIO ANANIA; EUSEBIO TOLU

    1997-01-01

    The effect of atrazine oral administration on cerebellar forelimb projection area was studied in rats in vivo. Rats acutely treated with atrazine (100 mg kg–1, BW) showed a significant decrease in spontaneous Purkinje cell firing rate. Atrazine also decreased the cerebellar potentials evoked by electrical stimulation of the ipsilateral radial nerve, affecting mostly the response to climbing fiber input. These

  2. Delayed Emergence from Anesthesia Resulting from Cerebellar Hemorrhage During Cervical Spine Surgery

    Microsoft Academic Search

    Koichi Nakazawa; Mamoru Yamamoto; Kunihiko Murai; Seiji Ishikawa; Tokujiro Uchida; Koshi Makita

    2005-01-01

    Cerebellarhemorrhageisanunpredictablecomplica- tion of spinal surgery. We encountered a case of cer- ebellar hemorrhage presenting with delayed emer- gence from anesthesia and hemiplegia after resection of an intradural extramedullar tumor from the cervi- calspine.Postoperativebraincomputedtomography revealedhematomainthecerebellarvermisandright cerebellar hemisphere. The patient made a gradual recovery with conservative treatment. Although the mechanism of cerebellar hemorrhage remains specu- lative, loss of cerebrospinal fluid may play

  3. Parvovirus associated cerebellar hypoplasia and hydrocephalus in day-old broiler chickens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cerebellar hypoplasia and hydrocephalus were detected in day-old broiler chickens. Brains of chickens evaluated at necropsy appeared to be abnormal; some were disfigured and cerebellae appeared to be smaller than normal. Histopathologic examination of brains revealed cerebellar folia that were sho...

  4. The Cerebellar Deficit Hypothesis and Dyslexic Tendencies in a Non-Clinical Sample

    ERIC Educational Resources Information Center

    Brookes, Rebecca L.; Stirling, John

    2005-01-01

    In order to assess the relationship between cerebellar deficits and dyslexic tendencies in a non-clinical sample, 27 primary school children aged 8-9 completed a cerebellar soft signs battery and were additionally assessed for reading age, sequential memory, picture arrangement and knowledge of common sequences. An average measure of the soft…

  5. Supraspinal cell populations projecting to the cerebellar cortex in the turtle ( Pseudemys scripta elegans )

    Microsoft Academic Search

    H. Künzle

    1983-01-01

    Neuronal cell populations giving rise to cerebellar projections in the turtle, Pseudemys scripta elegans, were analysed following injections of horseradish peroxidase into the cerebellar cortex. The most prominent retrograde cell labeling occurred bilaterally within the caudal rhombencephalon and especially in the ventral portion of the inferior reticular field. Based on the structural parameters of the labeled cells (size, dendritic tree),

  6. The role of the monkey sensory cortex in the recovery from cerebellar injury

    Microsoft Academic Search

    R. Mackel

    1987-01-01

    The aim of the study was to investigate the contribution of the primary sensory cortex in the compensation of cerebellar deficits during self-paced movements. For this purpose, monkeys were trained on motor tasks which required goal-reaching and independent finger movements. The intermediate and lateral deep cerebellar nuclei and the sensory cortex were lesioned in isolation and in sequence and the

  7. Cerebellar syndrome in myxoedema revisited: a published case with carcinomatosis and multiple system atrophy at necropsy.

    PubMed Central

    Quinn, N; Barnard, R O; Kelly, R E

    1992-01-01

    One of six patients in a 1960 paper on "Cerebellar syndrome in myxoedema" was subsequently found to have adenocarcinoma. General post-mortem revealed carcinomatosis and basal pneumonia. Neuropathological examination revealed the changes of multiple system atrophy. The relationship between hypothyroidism, carcinoma, and cerebellar, pontine and striatonigral degeneration is discussed. PMID:1640241

  8. The relationship between alcoholic cerebellar degeneration and cognitive and emotional functioning

    Microsoft Academic Search

    L. E. Fitzpatrick; M. Jackson; S. F. Crowe

    2008-01-01

    Although it is now widely acknowledged that the cerebellum contributes to the modulation of higher-order cognitive and emotional functions, this relationship has not been extensively explored in perhaps the largest group of individuals with cerebellar damage, chronic alcoholics. Localised damage to the cerebellum has been associated with a specific constellation of deficits and has been termed the ‘cerebellar cognitive affective

  9. Incidence of Dysarthria in Children with Cerebellar Tumors: A Prospective Study

    ERIC Educational Resources Information Center

    Richter, S.; Schoch, B.; Ozimek, A.; Gorissen, B.; Hein-Kropp, C.; Kaiser, O.; Hovel, M.; Wieland, R.; Gizewski, E.; Timmann, D.

    2005-01-01

    The present study investigated dysarthric symptoms in children with cerebellar tumors. Ten children with cerebellar tumors and 10 orthopedic control children were tested prior and one week after surgery. Clinical dysarthric symptoms were quantified in spontaneous speech. Syllable durations were analyzed in syllable repetition and sentence…

  10. Mechanisms of human cerebellar dysmetria: experimental evidence and current conceptual bases

    Microsoft Academic Search

    Mario Manto

    2009-01-01

    The human cerebellum contains more neurons than any other region in the brain and is a major actor in motor control. Cerebellar circuitry is unique by its stereotyped architecture and its modular organization. Understanding the motor codes underlying the organization of limb movement and the rules of signal processing applied by the cerebellar circuits remains a major challenge for the

  11. Validation of Genome-Wide Prostate Cancer Associations in Men of African Descent

    PubMed Central

    Chang, Bao-Li; Spangler, Elaine; Gallagher, Stephen; Haiman, Christopher A.; Henderson, Brian; Isaacs, William; Benford, Marnita L.; Kidd, LaCreis R.; Cooney, Kathleen; Strom, Sara; Ann Ingles, Sue; Stern, Mariana C.; Corral, Roman; Joshi, Amit D.; Xu, Jianfeng; Giri, Veda N.; Rybicki, Benjamin; Neslund-Dudas, Christine; Kibel, Adam S.; Thompson, Ian M.; Leach, Robin J.; Ostrander, Elaine A.; Stanford, Janet L.; Witte, John; Casey, Graham; Eeles, Rosalind; Hsing, Ann W.; Chanock, Stephen; Hu, Jennifer J.; John, Esther M.; Park, Jong; Stefflova, Klara; Zeigler-Johnson, Charnita; Rebbeck, Timothy R.

    2010-01-01

    Background Genome-wide association studies (GWAS) have identified numerous prostate cancer susceptibility alleles, but these loci have been identified primarily in men of European descent. There is limited information about the role of these loci in men of African descent. Methods We identified 7,788 prostate cancer cases and controls with genotype data for 47 GWAS-identified loci. Results We identified significant associations for SNP rs10486567 at JAZF1, rs10993994 at MSMB, rs12418451 and rs7931342 at 11q13, and rs5945572 and rs5945619 at NUDT10/11. These associations were in the same direction and of similar magnitude as those reported in men of European descent. Significance was attained at all report prostate cancer susceptibility regions at chromosome 8q24, including associations reaching genome-wide significance in region 2. Conclusion We have validated in men of African descent the associations at some, but not all, prostate cancer susceptibility loci originally identified in European descent populations. This may be due to heterogeneity in genetic etiology or in the pattern of genetic variation across populations. Impact The genetic etiology of prostate cancer in men of African descent differs from that of men of European descent. PMID:21071540

  12. Cerebellar Ataxia from Multiple Potential Causes: Hypothyroidism, Hashimoto's Thyroiditis, Thalamic Stimulation, and Essential Tremor

    PubMed Central

    Shneyder, Natalya; Lyons, Mark K.; Driver-dunckley, Erika; Evidente, Virgilio Gerald H.

    2012-01-01

    Background Both hypothyroidism and Hashimoto's thyroiditis (HT) can rarely be associated with cerebellar ataxia. Severe essential tremor (ET) as well as bilateral thalamic deep brain stimulation (DBS) may lead to subtle cerebellar signs. Case Report We report a 74-year-old male with hypothyroidism and a 20-year history of ET who developed cerebellar ataxia after bilateral thalamic DBS. Extensive workup revealed elevated thyroid stimulating hormone and thyroperoxidase antibody titers confirming the diagnosis of HT. Discussion Our case demonstrates multiple possible causes of cerebellar ataxia in a patient, including hypothyroidism, HT, chronic ET, and bilateral thalamic DBS. Counseling of patients may be appropriate when multiple risk factors for cerebellar ataxia coexist in one individual. PMID:23439792

  13. Neurofilament Protein Levels: Quantitative Analysis in Essential Tremor Cerebellar Cortex

    PubMed Central

    Louis, Elan D.; Karen; Babij, Rachel; Cortés, Etty; Liem, Ronald K.; Vonsattel, Jean-Paul G.; Faust, Phyllis L.

    2012-01-01

    Essential tremor (ET) is among the most prevalent neurological diseases. A substantial increase in the number of Purkinje cell axonal swellings (torpedoes) has been identified in ET brains. We recently demonstrated that torpedoes in ET contain an over-accumulation of disorganized neurofilament (NF) proteins. This now raises the question whether NF protein composition and/or phosphorylation state in cerebellar tissue might differ between ET cases and controls. We used a Western blot analysis to compare the levels and phosphorylation state of NF proteins and ?-internexin in cerebellar tissue from 47 ET cases vs. 26 controls (2:1 ratio). Cases and controls did not differ with respect to the cerebellar levels of NF-light (NF-L), NF-medium (NF-M), NF-heavy (NF-H), or ?-internexin. However, SMI-31 levels (i.e., phosphorylated NF-H) and SMI-32 levels (i.e., non-phosphorylated NF-H) were significantly higher in ET cases than controls (1.28 ± 0.47 vs. 1.06 ± 0.32, p = 0.02; and 1.38 ± 0.75 vs. 1.00 ± 0.42, p = 0.006). Whether the abnormal phosphorylation state that we observed is a cause of defective axonal transport and/or function of NFs in ET is not known. NF abnormalities have been demonstrated in several neurodegenerative diseases. Regardless of whether these protein aggregates are the cause or consequence of these diseases, NF abnormalities have been shown to be an important factor in the cellular disruption observed in several neurodegenerative diseases. Therefore, further analyses of these NF abnormalities and their mechanisms are important to enhance our understanding of disease pathogenesis in ET. PMID:22561033

  14. Neurofilament protein levels: quantitative analysis in essential tremor cerebellar cortex.

    PubMed

    Louis, Elan D; Ma, Karen; Babij, Rachel; Cortés, Etty; Liem, Ronald K; Vonsattel, Jean-Paul G; Faust, Phyllis L

    2012-06-14

    Essential tremor (ET) is among the most prevalent neurological diseases. A substantial increase in the number of Purkinje cell axonal swellings (torpedoes) has been identified in ET brains. We recently demonstrated that torpedoes in ET contain an over-accumulation of disorganized neurofilament (NF) proteins. This now raises the question whether NF protein composition and/or phosphorylation state in cerebellar tissue might differ between ET cases and controls. We used a Western blot analysis to compare the levels and phosphorylation state of NF proteins and ?-internexin in cerebellar tissue from 47 ET cases versus 26 controls (2:1 ratio). Cases and controls did not differ with respect to the cerebellar levels of NF-light (NF-L), NF-medium (NF-M), NF-heavy (NF-H), or ?-internexin. However, SMI-31 levels (i.e., phosphorylated NF-H) and SMI-32 levels (i.e., non-phosphorylated NF-H) were significantly higher in ET cases than controls (1.28±0.47 vs. 1.06±0.32, p=0.02; and 1.38±0.75 vs. 1.00±0.42, p=0.006). Whether the abnormal phosphorylation state that we observed is a cause of defective axonal transport and/or function of NFs in ET is not known. NF abnormalities have been demonstrated in several neurodegenerative diseases. Regardless of whether these protein aggregates are the cause or consequence of these diseases, NF abnormalities have been shown to be an important factor in the cellular disruption observed in several neurodegenerative diseases. Therefore, further analyses of these NF abnormalities and their mechanisms are important to enhance our understanding of disease pathogenesis in ET. PMID:22561033

  15. Aberrant cerebellar connectivity in motor and association networks in schizophrenia

    PubMed Central

    Shinn, Ann K.; Baker, Justin T.; Lewandowski, Kathryn E.; Öngür, Dost; Cohen, Bruce M.

    2015-01-01

    Schizophrenia is a devastating illness characterized by disturbances in multiple domains. The cerebellum is involved in both motor and non-motor functions, and the “cognitive dysmetria” and “dysmetria of thought” models propose that abnormalities of the cerebellum may contribute to schizophrenia signs and symptoms. The cerebellum and cerebral cortex are reciprocally connected via a modular, closed-loop network architecture, but few schizophrenia neuroimaging studies have taken into account the topographical and functional heterogeneity of the cerebellum. In this study, using a previously defined 17-network cerebral cortical parcellation system as the basis for our functional connectivity seeds, we systematically investigated connectivity abnormalities within the cerebellum of 44 schizophrenia patients and 28 healthy control participants. We found selective alterations in cerebro-cerebellar functional connectivity. Specifically, schizophrenia patients showed decreased cerebro-cerebellar functional connectivity in higher level association networks (ventral attention, salience, control, and default mode networks) relative to healthy control participants. Schizophrenia patients also showed increased cerebro-cerebellar connectivity in somatomotor and default mode networks, with the latter showing no overlap with the regions found to be hypoconnected within the same default mode network. Finally, we found evidence to suggest that somatomotor and default mode networks may be inappropriately linked in schizophrenia. The relationship of these dysconnectivities to schizophrenia symptoms, such as neurological soft signs and altered sense of agency, is discussed. We conclude that the cerebellum ought to be considered for analysis in all future studies of network abnormalities in SZ, and further suggest the cerebellum as a potential target for further elucidation, and possibly treatment, of the underlying mechanisms and network abnormalities producing symptoms of schizophrenia.

  16. Description of the computations and pilot procedures for planning fuel-conservative descents with a small programmable calculator

    SciTech Connect

    Vicroy, D.D.; Knox, C.E.

    1983-05-01

    A simplified flight management descent algorithm was developed and programmed on a small programmable calculator. It was designed to aid the pilot in planning and executing a fuel conservative descent to arrive at a metering fix at a time designated by the air traffic control system. The algorithm may also be used for planning fuel conservative descents when time is not a consideration. The descent path was calculated for a constant Mach/airspeed schedule from linear approximations of airplane performance with considerations given for gross weight, wind, and nonstandard temperature effects. The flight management descent algorithm and the vertical performance modeling required for the DC-10 airplane is described.

  17. Description of the computations and pilot procedures for planning fuel-conservative descents with a small programmable calculator

    NASA Technical Reports Server (NTRS)

    Vicroy, D. D.; Knox, C. E.

    1983-01-01

    A simplified flight management descent algorithm was developed and programmed on a small programmable calculator. It was designed to aid the pilot in planning and executing a fuel conservative descent to arrive at a metering fix at a time designated by the air traffic control system. The algorithm may also be used for planning fuel conservative descents when time is not a consideration. The descent path was calculated for a constant Mach/airspeed schedule from linear approximations of airplane performance with considerations given for gross weight, wind, and nonstandard temperature effects. The flight management descent algorithm and the vertical performance modeling required for the DC-10 airplane is described.

  18. Late effects of radiotherapy on patients with cerebellar medulloblastoma

    SciTech Connect

    Silverman, C.L.; Palkes, H.; Talent, B.; Kovnar, E.; Clouse, J.W.; Thomas, P.R.

    1984-09-01

    Nine long-term survivors of cerebellar medulloblastoma treated with surgery and irradiation were retrospectively examined with a complete battery of neuropsychological tests and the results compared with their nonirradiated siblings. Significant decreased scores were found in the full-scale intelligence quotients (IQ), performance IQ, and verbal IQ with all nine irradiated patients scoring below their siblings. Also, educational quotients (EQ) of the irradiated patients were 12 to 17 points below the nonirradiated siblings with arithmetic EQ significantly decreased. Most severely affected were those children younger than 8 years at time of irradiation. No correlation was found with whole-brain dose, or objective physical or neurologic findings.

  19. The reciprocal cerebellar circuitry in human hereditary ataxia

    PubMed Central

    Koeppen, Arnulf H.; Ramirez, R. Liane; Bjork, Sarah T.; Bauer, Peter; Feustel, Paul J.

    2013-01-01

    Clinicoanatomic correlation in the spinocerebellar ataxias (SCA) and Friedreich’s ataxia (FRDA) is difficult as these diseases differentially affect multiple sites in the central and peripheral nervous systems. A new way to study cerebellar ataxia is the systematic analysis of the “reciprocal cerebellar circuitry” that consists of tightly organized reciprocal connections between Purkinje cells, dentate nuclei (DN), and inferior olivary nuclei (ION). This circuitry is similar to but not identical to the “cerebellar module” in experimental animals. Neurohumoral transmitters operating in the circuitry are both inhibitory (?-aminobutyric acid [GABA] in corticonuclear and dentato-olivary fibers) and excitatory (glutamate in olivocerebellar or climbing fibers). Glutamatergic climbing fibers also issue collaterals to the DN. The present study applied 5 immunohistochemical markers in six types of SCA (1, 2, 3, 6, 7, 17), genetically undefined SCA, FRDA, and FRDA carriers to identify interruptions within the circuitry: calbindin-D28k; neuron-specific enolase (NSE); glutamic acid decarboxylase (GAD); and vesicular glutamate transporters (VGluT) 1 and 2. Lesions of the cerebellar cortex, DN, and ION were scored according to a guide as 0 (normal); 1 (mild); 2 (moderate); and 3 (severe). Results of each of the 5 immunohistochemical stains were examined separately for each of the 3 regions. Combining scores of each anatomical region and each stain yielded a total score as an indicator of pathological severity. Total scores ranged from 16 to 38 in SCA-1 (9 cases); 22 to 39 in SCA-2 (6 cases); 9 to 15 in SCA-3 (4 cases); and 13 and 25 in SCA-6 (2 cases). In single cases of SCA-7 and SCA-17, scores were 16 and 31, respectively. In 2 genetically undefined SCA, scores were 36 and 37, respectively. In 9 cases of FRDA, total scores ranged from 11 to 19. The low scores in SCA-3 and FRDA reflect selective atrophy of the DN. The FRDA carriers did not differ from normal controls. These observations offer a semiquantitative assessment of the critical role of the DN in the ataxic phenotype of SCA and FRDA while other parts of the circuitry appear less important. PMID:23389921

  20. Extra-Axial Medulloblastoma in the Cerebellar Hemisphere

    PubMed Central

    Chung, Eui Jin

    2014-01-01

    Extra-axial medulloblastoma is a rare phenomenon. We report a case in a 5-year-old boy who presented with nausea, vomiting, and gait disturbance. He was treated with total removal of the tumor. This is the first case of an extra-axially located medulloblastoma occurring in the cerebellar hemisphere posteriolateral to the cerebellopontine angle in Korea. Although the extra-axial occurrence of medulloblastoma is rare, it should be considered in the differential diagnosis of extra-axial lesions of the posterior fossa in children. PMID:25237434

  1. Ionic mechanisms of autorhythmic firing in rat cerebellar Golgi cells

    PubMed Central

    Elisabetta Cesana, Lia Forti; Mapelli, Jonathan; D'Angelo, Egidio

    2006-01-01

    Although Golgi cells (GoCs), the main type of inhibitory interneuron in the cerebellar granular layer (GL), are thought to play a central role in cerebellar network function, their excitable properties have remained unexplored. GoCs fire rhythmically in vivo and in slices, but it was unclear whether this activity originated from pacemaker ionic mechanisms. We explored this issue in acute cerebellar slices from 3-week-old rats by combining loose cell-attached (LCA) and whole-cell (WC) recordings. GoCs displayed spontaneous firing at 1–10 Hz (room temperature) and 2–20 Hz (35–37°C), which persisted in the presence of blockers of fast synaptic receptors and mGluR and GABAB receptors, thus behaving, in our conditions, as pacemaker neurons. ZD 7288 (20 ?m), a potent hyperpolarization-activated current (Ih) blocker, slowed down pacemaker frequency. The role of subthreshold Na+ currents (INa,sub) could not be tested directly, but we observed a robust TTX-sensitive, non-inactivating Na+ current in the subthreshold voltage range. When studying repolarizing currents, we found that retigabine (5 ?m), an activator of KCNQ K+ channels generating neuronal M-type K+ (IM) currents, reduced GoC excitability in the threshold region. The KCNQ channel antagonist XE991 (5 ?m) did not modify firing, suggesting that GoC IM has low XE991 sensitivity. Spike repolarization was followed by an after-hyperpolarization (AHP) supported by apamin-sensitive Ca2+-dependent K+ currents (Iapa). Block of Iapa decreased pacemaker precision without altering average frequency. We propose that feed-forward depolarization is sustained by Ih and INa,sub, and that delayed repolarizing feedback involves an IM-like current whose properties remain to be characterized. The multiple ionic mechanisms shown here to contribute to GoC pacemaking should provide the substrate for fine regulation of firing frequency and precision, thus influencing the cyclic inhibition exerted by GoCs onto the cerebellar GL. PMID:16690702

  2. Cerebellar gray matter and lobular volumes correlate with core autism symptoms

    PubMed Central

    D'Mello, Anila M.; Crocetti, Deana; Mostofsky, Stewart H.; Stoodley, Catherine J.

    2015-01-01

    Neuroanatomical differences in the cerebellum are among the most consistent findings in autism spectrum disorder (ASD), but little is known about the relationship between cerebellar dysfunction and core ASD symptoms. The newly-emerging existence of cerebellar sensorimotor and cognitive subregions provides a new framework for interpreting the functional significance of cerebellar findings in ASD. Here we use two complementary analyses — whole-brain voxel-based morphometry (VBM) and the SUIT cerebellar atlas — to investigate cerebellar regional gray matter (GM) and volumetric lobular measurements in 35 children with ASD and 35 typically-developing (TD) children (mean age 10.4 ± 1.6 years; range 8–13 years). To examine the relationships between cerebellar structure and core ASD symptoms, correlations were calculated between scores on the Autism Diagnostic Observation Schedule (ADOS) and Autism Diagnostic Interview (ADI) and the VBM and volumetric data. Both VBM and the SUIT analyses revealed reduced GM in ASD children in cerebellar lobule VII (Crus I/II). The degree of regional and lobular gray matter reductions in different cerebellar subregions correlated with the severity of symptoms in social interaction, communication, and repetitive behaviors. Structural differences and behavioral correlations converged on right cerebellar Crus I/II, a region which shows structural and functional connectivity with fronto-parietal and default mode networks. These results emphasize the importance of the location within the cerebellum to the potential functional impact of structural differences in ASD, and suggest that GM differences in cerebellar right Crus I/II are associated with the core ASD profile. PMID:25844317

  3. The olivo-cerebellar system as a neural clock.

    PubMed

    Ashe, James; Bushara, Khalaf

    2014-01-01

    The cerebellum, and the olivo-cerebellar system in particular, may be the central mechanism of a neural clock that provides a rhythmic neural signal used to time motor and cognitive processes. Several independent lines of evidence support this hypothesis. First, the resting membrane potential of neurons in the inferior olive oscillates at ~10 Hz and the neural input from the olive leads to rhythmic complex spikes in cerebellum Purkinje cells. Second, the repeating modular microstructure of the cerebellum is ideally suited for performing computations underlying a basic neural process such as timing. Third, damage to the cerebellum leads to deficits in the perception of time and in the production of timed movements. Fourth, functional imaging studies in human subjects have shown activation of the inferior olive specifically during time perception. However, additional data on the exact role of rhythmic cerebellar activity during basis motor and sensory processing will be necessary before the hypothesis that the cerebellum is a neural clock is more widely accepted. PMID:25358710

  4. Cerebellar hypoperfusion and developmental dysphasia in a male.

    PubMed

    Oki, J; Takahashi, S; Miyamoto, A; Tachibana, Y

    1999-10-01

    A male with developmental dysphasia is documented with fine motor dysfunction whose improvement in expressive language was associated with increased cerebellar perfusion, as detected by serial N-isopropyl-p-[iodine-123] iodoamphetamine single photon emission computed tomography (SPECT). His expressive language has been improving since 6 years, 8 months of age, and his verbal intelligence quotient improved from less than 45 at 5 years of age to 80 at 8 years of age. Compared with the SPECT findings at 4 years of age, the ratio of the average pixel values of the cerebellum to the frontal cortices increased at 9 years of age (from 0.81 to 1.03-1.09 in the hemisphere and from 0.66 to 0.98 in the vermis). However, he was not able to understand stories presented orally even at 9 years, 4 months of age. These results suggest that developmental dysphasia, which mostly involves expressive impairment, in this patient could have been the result of delayed maturation of cerebellar function, mainly that of the vermis. PMID:10580890

  5. Cytosine arabinoside induces apoptosis in cerebellar neurons in culture.

    PubMed

    Dessi, F; Pollard, H; Moreau, J; Ben-Ari, Y; Charriaut-Marlangue, C

    1995-05-01

    Cytosine arabinoside (AraC) is a pyrimidine antimetabolite that prevents cell proliferation by inhibiting DNA synthesis. We report that AraC kills cultured cerebellar neurons in a concentration-dependent fashion with an EC50 of approximately 60 microM when added shortly after seeding. This cell death has apoptotic features because we observed (1) morphology of apoptotic nuclei as judged by DNA staining with Hoechst 33258, (2) DNA fragmentation with typical ladder pattern on agarose gel, (3) positive nuclear labeling with a specific in situ DNA fragmentation staining, (4) prevention by deoxycytidine (IC50 = 1 microM), protein, and RNA synthesis inhibitors, and (5) release of DNA fragments in the incubating medium. We have also observed that several proteins were overexpressed in AraC-treated neurons by two-dimensional polyacrylamide gel electrophoresis. We conclude that AraC induces a signal that triggers a cascade of new mRNA and protein synthesis, leading to apoptotic cell death in cultured cerebellar granule cells. PMID:7536801

  6. Cerebellar allocentric and action-intentional spatial neglect.

    PubMed

    Milano, Nicholas J; Heilman, Kenneth M

    2014-09-01

    Contralesional hemispatial neglect most often results from lesions in the right posterior temporoparietal cortex. Less commonly, contralesional and ipsilesional neglect are caused by lesions in the frontal lobe. Although unilateral left cerebellar lesions have been reported to cause body-centered (egocentric) ipsilesional neglect, they have not been reported to cause left-side object-centered (allocentric) neglect together with a leftward action-intentional bias. We describe a patient who had these signs of neglect 7 months after a left cerebellar hemorrhage. This 61-year-old right-handed woman reported emotional lability and difficulty walking, frequently bumping into things on her left side. Neurologic examination revealed ocular dysmetria and left-side limb ataxia. Neuropsychological tests showed evidence of neglect. On a clock-drawing test, the patient accurately drew a circle but her number placement deviated to the left side. She showed the same leftward deviation when she tried to draw a circle composed of small triangles. Although her line bisection was normal, on an allocentric task of open-triangle cancellation she was most likely to neglect triangles with a left-side opening. Her performance on this task indicated left allocentric neglect. Her leftward deviation on the clock and figure drawing tasks seems to be a form of an action-intentional grasp, which may have been induced by right frontal dysfunction superimposed on a deficit of global attention. PMID:25237748

  7. Congenital disorders of glycosylation with emphasis on cerebellar involvement.

    PubMed

    Barone, Rita; Fiumara, Agata; Jaeken, Jaak

    2014-07-01

    Congenital disorders of glycosylation (CDG) are genetic diseases due to defective glycosylation of proteins and lipids. The authors present an update on these disorders affecting the central nervous system with a focus on cerebellar involvement. The rate of identification of novel CDG shows an exponential increase. Some 76 CDG are actually known, not taking into account the defects in glycan-modifying proteins. Neurologic involvement is present in the large majority of CDG. Screening methods are limited to serum transferrin isoelectrofocusing (for N-glycosylation disorders with sialic acid deficiency), and serum apolipoprotein C-III isoelectrofocusing (for core 1 mucin-type O-glycosylation disorders). Whole exome/genome sequencing is increasingly used in the diagnostic workup of patients with CDG-X. Treatment is greatly lagging behind because only one CDG is efficiently treatable (MPI-CDG). Cerebellar involvement is an important feature of PMM2-CDG, the congenital muscular dystrophies due to dystroglycanopathy, and SRD5A3-CDG. It has also been reported in some patients with ALG1-CDG, ALG3-CDG, ALG9-CDG, ALG6-CDG, ALG8-CDG, PIGA-CDG, DPM1-CDG, DPM2-CDG, B4GALT1-CDG, SLC35A2-CDG, COG1-CDG, COG5-CDG, COG7-CDG, and COG8-CDG. PMID:25192513

  8. Cerebellar sequencing: a trick for predicting the future.

    PubMed

    Leggio, M; Molinari, M

    2015-02-01

    "Looking into the future" well depicts one of the most significant concepts in cognitive neuroscience: the brain is constantly predicting future events. Such directedness toward the future has been recognized to be relevant to and beneficial for many aspects of information processing in humans, such as perception, motor and cognitive control, decision-making, theory of mind, and other cognitive processes. Because one of the most adaptive characteristics of the brain is to correct errors, the ability to look into the future represents the best chance to avoid repeating errors. Within the structures that constitute the "predictive brain," the cerebellum has been proposed to have a central function, based on its ability to generate internal models. We suggested that "sequence detection" is the operational mode of the cerebellum in predictive processing. According to this hypothesis, the cerebellum detects and simulates repetitive patterns of temporally or spatially structured events and generates internal models that can be used to make predictions. Consequently, we demonstrate that the cerebellum recognizes serial events as a sequence, detects a sequence violation, and successfully reconstructs the correct sequence of events. Thus, we hypothesize that pattern detection and prediction and processing of anticipation are cerebellum-specific functions within the brain and that the sequence detection hypothesis links the multifarious impairments that are reported in patients with cerebellar damage. We propose that this cerebellar operational mode can advance our understanding of the pathophysiological mechanisms in various clinical conditions, such as schizophrenia and autism. PMID:25331541

  9. Joubert syndrome: congenital cerebellar ataxia with the “molar tooth”

    PubMed Central

    Romani, Marta; Micalizzi, Alessia; Valente, Enza Maria

    2013-01-01

    Joubert syndrome (JS) is a congenital cerebellar ataxia with autosomal recessive or X-linked inheritance, which diagnostic hallmark is a unique cerebellar and brainstem malformation recognizable on brain imaging, the “molar tooth sign”. Neurological signs are present from neonatal age and include hypotonia evolving into ataxia, global developmental delay, ocular motor apraxia and breathing dysregulation. These are variably associated with multiorgan involvement, mainly of the retina, kidneys, skeleton and liver. To date, 21 causative genes have been identified, all encoding for proteins of the primary cilium or its apparatus. This is a subcellular organelle that plays key roles in development and in many cellular functions, making JS part of the expanding family of ciliopathies. There is marked clinical and genetic overlap among distinct ciliopathies, which may co-occur even within families. Such variability is likely explained by an oligogenic model of inheritance, in which mutations, rare variants and polymorphisms at distinct loci interplay to modulate the expressivity of the ciliary phenotype. PMID:23870701

  10. Expression of HIV receptors, alternate receptors and co-receptors on tonsillar epithelium: implications for HIV binding and primary oral infection

    PubMed Central

    Kumar, Renu B; Maher, Diane M; Herzberg, Mark C; Southern, Peter J

    2006-01-01

    Background Primary HIV infection can develop from exposure to HIV in the oral cavity. In previous studies, we have documented rapid and extensive binding of HIV virions in seminal plasma to intact mucosal surfaces of the palatine tonsil and also found that virions readily penetrated beneath the tissue surfaces. As one approach to understand the molecular interactions that support HIV virion binding to human mucosal surfaces, we have examined the distribution of the primary HIV receptor CD4, the alternate HIV receptors heparan sulfate proteoglycan (HS) and galactosyl ceramide (GalCer) and the co-receptors CXCR4 and CCR5 in palatine tonsil. Results Only HS was widely expressed on the surface of stratified squamous epithelium. In contrast, HS, GalCer, CXCR4 and CCR5 were all expressed on the reticulated epithelium lining the tonsillar crypts. We have observed extensive variability, both across tissue sections from any tonsil and between tonsils, in the distribution of epithelial cells expressing either CXCR4 or CCR5 in the basal and suprabasal layers of stratified epithelium. The general expression patterns of CXCR4, CCR5 and HS were similar in palatine tonsil from children and adults (age range 3–20). We have also noted the presence of small clusters of lymphocytes, including CD4+ T cells within stratified epithelium and located precisely at the mucosal surfaces. CD4+ T cells in these locations would be immediately accessible to HIV virions. Conclusion In total, the likelihood of oral HIV transmission will be determined by macro and micro tissue architecture, cell surface expression patterns of key molecules that may bind HIV and the specific properties of the infectious inoculum. PMID:16600047

  11. Reduced Expression of the Antigen Processing Machinery Components TAP2, LMP2, and LMP7 in Tonsillar and Base of Tongue Cancer and Implications for Clinical Outcome1

    PubMed Central

    Tertipis, Nikolaos; Haeggblom, Linnea; Grün, Nathalie; Nordfors, Cecilia; Näsman, Anders; Dalianis, Tina; Ramqvist, Torbjörn

    2015-01-01

    OBJECTIVES: Patients with human papillomavirus (HPV)–positive tonsillar squamous cell carcinoma (TSCC) and base of tongue squamous cell carcinoma (BOTSCC) have a better clinical outcome than those with corresponding HPV-negative tumors. Moreover, there is a strong positive correlation between absent/low as opposed to strong HLA class I expression and favorable clinical outcome for HPV-positive tumors, while the reverse applies to HPV-negative tumors. The expression of the antigen processing machinery (APM) components TAP1, TAP2, LMP2, and LMP7 in these tumors in relation to HPV status, HLA class I expression, each other, and clinical outcome was therefore investigated. MATERIAL AND METHODS: Formalin-fixed paraffin-embedded TSCC and BOTSCC, derived from 151 patients and previously analyzed for HPV DNA, HLA class I, and LMP10 expression were stained by immunohistochemistry for TAP1, TAP2, LMP2, and LMP7. RESULTS: Absent/low TAP2, LMP2, and LMP7 expression, similar to HLA class I and LMP10, was common in TSCC and BOTSCC, irrespective of HPV status. Expression of TAP1 and TAP2 was correlated, as was LMP2 to LMP7. LMP2 and LMP7 expression was also associated to HLA class I expression. Moreover, absence of LMP7 was linked to increased disease-free survival in both HPV-positive and HPV-negative cases. CONCLUSION: Reduced expression of TAP2, LMP2, and LMP7 was frequent in TSCC and BOTSCC and their expression as well as that of TAP1 was often interrelated. Furthermore, low LMP7 expression correlated to better clinical outcome and may, together with HPV status, potentially be used for prediction of treatment response. PMID:25749172

  12. Low-dose cisplatin converts the tumor microenvironment into a permissive state for HSVtk-induced antitumor immunity in HPV16-related tonsillar carcinoma.

    PubMed

    Goh, Ah Ra; Shin, Seung-Pil; Jung, Na-Rae; Ryu, Chang-Hwan; Eom, Hyeon Seok; Lee, John H; Choi, Kyungho; Lee, Sang-Jin; Jung, Yuh-S

    2015-01-28

    An adenovirus harboring the HSV thymidine kinase (HSVtk) gene under the regulation of a trans-splicing ribozyme that targets telomerase is cytotoxic to cancer cells because it inhibits DNA replication (Ad5mTR). Furthermore, it induces anti-tumor immunity by activating cytotoxic T cells. Because multiple chemotherapeutic agents also activate cytotoxic T-cell immunity during the direct killing process of tumor cells, we herein explored whether low-dose cisplatin could synergize with cytotoxic Ad5mTR to potentiate its therapeutic effect by boosting anti-tumor immunity in a murine HPV16-associated tonsillar carcinoma model. Tumor regression was enhanced when low-dose (1?mg/kg) cisplatin was added to suicide gene therapy using Ad5mTR. Meanwhile, 1?mg/kg cisplatin alone had no tumor-suppressive effects and did not result in any systemic toxicity. Thus, cisplatin along with Ad5mTR improved tumor clearance by increasing the number of E7-specific CD8+ T cells. Specifically, analysis of the tumors and lymph nodes supported improved immune clearance by increasing the number of E7-specific CD8+ T cells inside tumors (40%, P?

  13. Detection of Postmortem Human Cerebellar Cortex and White Matter Pathways Using High Angular Resolution Diffusion Tractography: A feasibility study

    PubMed Central

    Takahashi, Emi; Song, Jae W.; Folkerth, Rebecca D.; Grant, P. Ellen; Schmahmann, Jeremy D.

    2015-01-01

    Imaging three-dimensional cerebellar connectivity using diffusion tractography is challenging because of the ubiquitous features of crossing axonal pathways within a folium as well as intersecting pathways from neighboring folia. We applied high-angular resolution diffusion imaging (HARDI) tractography to intact postmortem adult brainstem and cerebellum to examine the 3-dimensional white matter and local gray matter pathways. The middle cerebellar peduncles conveyed fibers from the rostral pons to the lateral and caudal aspects of the cerebellar hemisphere, and from the caudal pons to medial and rostral parts of the cerebellar hemisphere. In the cerebellar cortex, tractography detected tangential coherence superficially in the cerebellar cortex and revealed fibers coursing parallel to the long axis of the folia. These fibers were consistent with the location and direction of parallel fibers in the molecular layer. Crossing with these parallel fibers were tangential fibers running perpendicular to the long axis of the folia, consistent with axons othe cortical interneurons – stellate cells and basket cells. These tangential fibers within the cerebellar cortex were distinct from fibers linking the cerebellar cortex with the deep cerebellar nuclei and the brainstem. Our results show the potential for HARDI tractography to resolve axonal pathways from different neuronal elements within the cerebellar cortex, and improve our understanding of adult cerebellar neural circuitry and connectivity in both white and gray matter. PMID:23238434

  14. A conflict analysis of 4D descent strategies in a metered, multiple-arrival route environment

    NASA Technical Reports Server (NTRS)

    Izumi, K. H.; Harris, C. S.

    1990-01-01

    A conflict analysis was performed on multiple arrival traffic at a typical metered airport. The Flow Management Evaluation Model (FMEM) was used to simulate arrival operations using Denver Stapleton's arrival route structure. Sensitivities of conflict performance to three different 4-D descent strategies (clear-idle Mach/Constant AirSpeed (CAS), constant descent angle Mach/CAS and energy optimal) were examined for three traffic mixes represented by those found at Denver Stapleton, John F. Kennedy and typical en route metering (ERM) airports. The Monte Carlo technique was used to generate simulation entry point times. Analysis results indicate that the clean-idle descent strategy offers the best compromise in overall performance. Performance measures primarily include susceptibility to conflict and conflict severity. Fuel usage performance is extrapolated from previous descent strategy studies.

  15. A taxonomy of descent algorithms for nonlinear programs and variational inequalities

    E-print Network

    Patriksson, Michael

    A taxonomy of descent algorithms for nonlinear programs and the choices of cost approximating mappings and merit functions. The* * taxonomy is illustrated on classical algorithms and is utilized to interrelate known alg* *orithm frameworks. Keywords. Taxonomy

  16. User's manual for a fuel-conservative descent planning algorithm implemented on a small programmable calculator

    NASA Technical Reports Server (NTRS)

    Vicroy, D. D.

    1984-01-01

    A simplified flight management descent algorithm was developed and programmed on a small programmable calculator. It was designed to aid the pilot in planning and executing a fuel conservative descent to arrive at a metering fix at a time designated by the air traffic control system. The algorithm may also be used for planning fuel conservative descents when time is not a consideration. The descent path was calculated for a constant Mach/airspeed schedule from linear approximations of airplane performance with considerations given for gross weight, wind, and nonstandard temperature effects. An explanation and examples of how the algorithm is used, as well as a detailed flow chart and listing of the algorithm are contained.

  17. Antarctic Polar Descent and Planetary Wave Activity Observed in ISAMS CO from April to July 1992

    NASA Technical Reports Server (NTRS)

    Allen, D. R.; Stanford, J. L.; Nakamura, N.; Lopez-Valverde, M. A.; Lopez-Puertas, M.; Taylor, F. W.; Remedios, J. J.

    2000-01-01

    Antarctic polar descent and planetary wave activity in the upper stratosphere and lower mesosphere are observed in ISAMS CO data from April to July 1992. CO-derived mean April-to-May upper stratosphere descent rates of 15 K/day (0.25 km/day) at 60 S and 20 K/day (0.33 km/day) at 80 S are compared with descent rates from diabatic trajectory analyses. At 60 S there is excellent agreement, while at 80 S the trajectory-derived descent is significantly larger in early April. Zonal wavenumber 1 enhancement of CO is observed on 9 and 28 May, coincident with enhanced wave 1 in UKMO geopotential height. The 9 May event extends from 40 to 70 km and shows westward phase tilt with height, while the 28 May event extends from 40 to 50 km and shows virtually no phase tilt with height.

  18. Descent graphs in pedigree analysis: applications to haplotyping, location scores, and marker-sharing statistics.

    PubMed Central

    Sobel, E.; Lange, K.

    1996-01-01

    The introduction of stochastic methods in pedigree analysis has enabled geneticists to tackle computations intractable by standard deterministic methods. Until now these stochastic techniques have worked by running a Markov chain on the set of genetic descent states of a pedigree. Each descent state specifies the paths of gene flow in the pedigree and the founder alleles dropped down each path. The current paper follows up on a suggestion by Elizabeth Thompson that genetic descent graphs offer a more appropriate space for executing a Markov chain. A descent graph specifies the paths of gene flow but not the particular founder alleles traveling down the paths. This paper explores algorithms for implementing Thompson's suggestion for codominant markers in the context of automatic haplotyping, estimating location scores, and computing gene-clustering statistics for robust linkage analysis. Realistic numerical examples demonstrate the feasibility of the algorithms. PMID:8651310

  19. Increased gait variability in mice with small cerebellar cortex lesions and normal rotarod performance.

    PubMed

    Stroobants, Stijn; Gantois, Ilse; Pooters, Tine; D'Hooge, Rudi

    2013-03-15

    The physiological and pathophysiological role of the cerebellum in neuromotor performance and gait is a prominent research topic in contemporary brain research. However, it has proven difficult to measure subtle neuromotor changes and cerebellar dysfunction in laboratory rodents with some of the common behavioural assays. Rotarod assays and gait analyses have been used extensively as indicators of neuromotor performance, and more specifically, cerebellar function. Standard rotarod procedures fail to reveal subtle motor alterations, whereas automated gait analysis could be more sensitive in this respect. In the present study, we compared detailed treadmill gait analysis to the standard accelerating rotarod assay in its ability to reveal neuromotor alterations in mice with small bilateral lesions in the cerebellar cortex. This small lesion model showed no readily observable signs of ataxia or abnormal activity. In the rotarod test, cerebellar-lesioned mice performed at the level of control animals, and basic gait parameters were not altered. However, cerebellar-lesioned mice did show increased front base-width and hind stride length variability, as well as increased stride length incongruity between different paws. We conclude that small cerebellar lesions lead to increased gait variability as it does in humans with cerebellar dysfunction. Treadmill gait analysis is better suited than accelerating rotarod assays to measure such subtle neuromotor defects. PMID:23219967

  20. Regional cerebellar volume and cognitive function from adolescence to late middle age.

    PubMed

    Bernard, Jessica A; Leopold, Daniel R; Calhoun, Vince D; Mittal, Vijay A

    2015-03-01

    Cerebellar morphology and function have been implicated in a variety of developmental disorders, and in healthy aging. Although recent work has sought to characterize the relationships between volume and age in this structure during adolescence, young, and older adulthood, there have been no investigations of regional cerebellar volume from adolescence through late middle age. Middle age in particular has been largely understudied, and investigating this period of the lifespan may be especially important for our understanding of senescence. Understanding regional patterns of cerebellar volume with respect to age during this portion of the lifespan may provide important insight into healthy aging and cognitive function as well as pathology from adolescence into later life. We investigated regional cerebellar volume using a highly novel lobular segmentation approach in conjunction with a battery of cognitive tasks in a cross-sectional sample of 123 individuals from 12 to 65 years old. Our results indicated that regional cerebellar volumes show different patterns with respect to age. In particular, the more posterior aspect of the neocerebellum follows a quadratic "inverse-U" pattern while the vermis and anterior cerebellum follow logarithmic patterns. In addition, we quantified the relationships between age and a variety of cognitive assessments and found relationships between regional cerebellar volumes and performance. Finally, exploratory analyses of sex differences in the relationships between regional cerebellar volume, age, and cognition were investigated. Taken together, these results provide key insights into the development and aging of the human cerebellum, and its role in cognitive function across the lifespan. PMID:25395058

  1. Systemic glycerol decreases neonatal rabbit brain and cerebellar growth independent of intraventricular hemorrhage

    PubMed Central

    Traudt, Christopher M; McPherson, Ron J; Studholme, Colin; Millen, Kathleen J; Juul, Sandra E

    2014-01-01

    Background Cerebellar hypoplasia is common problem for preterm infants, and infants that suffer intraventricular hemorrhage (IVH). To evaluate the effects of IVH on cerebellar growth and development, we used a neonatal rabbit model of systemic glycerol to produce IVH. Methods New Zealand White rabbit kits were surgically delivered 2 d preterm, and treated with i.p. glycerol (3.25 to 6.5 g/kg). Controls were born at term. IVH was documented by ultrasound. Brain MRI volumes, cerebellar foliation, proliferation (Ki-67) and Purkinje cell density were done at two weeks of life. Tissue glycerol and glutathione concentrations were measured. Results Glycerol increased IVH, subarachnoid hemorrhages and mortality in a dose-dependent manner. Total cerebellar volumes, cerebellar foliation and cerebellar proliferation were decreased in a dose-dependent manner. Glycerol accumulated rapidly in blood, brain and liver and was associated with increased glutathione concentration. All of these results were independent of IVH status. Conclusions Cerebellar hypoplasia was induced after glycerol administration in a dose-dependent manner. Given rapid tissue accumulation of glycerol, dose dependent decreased brain growth and lack of IVH effect on measured outcomes we question the validity of this model as glycerol toxicity cannot be ruled out. A more physiologic model of IVH is needed. PMID:24346111

  2. Mechanisms of human cerebellar dysmetria: experimental evidence and current conceptual bases

    PubMed Central

    Manto, Mario

    2009-01-01

    The human cerebellum contains more neurons than any other region in the brain and is a major actor in motor control. Cerebellar circuitry is unique by its stereotyped architecture and its modular organization. Understanding the motor codes underlying the organization of limb movement and the rules of signal processing applied by the cerebellar circuits remains a major challenge for the forthcoming decades. One of the cardinal deficits observed in cerebellar patients is dysmetria, designating the inability to perform accurate movements. Patients overshoot (hypermetria) or undershoot (hypometria) the aimed target during voluntary goal-directed tasks. The mechanisms of cerebellar dysmetria are reviewed, with an emphasis on the roles of cerebellar pathways in controlling fundamental aspects of movement control such as anticipation, timing of motor commands, sensorimotor synchronization, maintenance of sensorimotor associations and tuning of the magnitudes of muscle activities. An overview of recent advances in our understanding of the contribution of cerebellar circuitry in the elaboration and shaping of motor commands is provided, with a discussion on the relevant anatomy, the results of the neurophysiological studies, and the computational models which have been proposed to approach cerebellar function. PMID:19364396

  3. Vision-Aided Inertial Navigation for Spacecraft Entry, Descent, and Landing

    Microsoft Academic Search

    Anastasios I. Mourikis; Nikolas Trawny; Stergios I. Roumeliotis; Andrew Edie Johnson; Adnan Ansar; Larry Matthies

    2009-01-01

    In this paper, we present the vision-aided inertial navigation (VISINAV) algorithm that enables precision planetary landing. The vision front-end of the VISINAV system extracts 2-D-to-3-D correspondences between descent images and a surface map (mapped landmarks), as well as 2-D-to-2-D feature tracks through a sequence of descent images (opportunistic features). An extended Kalman filter (EKF) tightly integrates both types of visual

  4. Dual Gradient Descent Algorithm on Two-Layered Feed-Forward Artificial Neural Networks

    Microsoft Academic Search

    Bumghi Choi; Ju-hong Lee; Tae-su Park

    2007-01-01

    The learning algorithms of multilayered feed-forward networks can be classified into two categories, gradient and non-gradient\\u000a kinds. The gradient descent algorithms like backpropagation (BP) or its variations are widely used in many application areas\\u000a because of convenience. However, the most serious problem associated with the BP is local minima problem. We propose an improved\\u000a gradient descent algorithm intended to weaken

  5. Relation between perineal descent and pudendal nerve damage in idiopathic faecal incontinence

    Microsoft Academic Search

    P. N. Jones; D. Z. Lubowski; M. Swash; M. M. Henry

    1987-01-01

    In 60 patients with idiopathic anorectal incontinence, without neurological disease, there was a significant relationship, shown by regression analysis, between the pudendal nerve terminal motor latency and the extent of perineal descent during straining (r0.59;p<0.001), and the plane of the perineum on straining (r-0.61;p<0.001). These data are consistent with the suggestion that perineal descent can lead to stretch-induced damage to

  6. Analysis of Flight Management System Predictions of Idle-Thrust Descents

    NASA Technical Reports Server (NTRS)

    Stell, Laurel

    2010-01-01

    To enable arriving aircraft to fly optimized descents computed by the flight management system (FMS) in congested airspace, ground automation must accurately predict descent trajectories. To support development of the predictor and its uncertainty models, descents from cruise to the meter fix were executed using vertical navigation in a B737-700 simulator and a B777-200 simulator, both with commercial FMSs. For both aircraft types, the FMS computed the intended descent path for a specified speed profile assuming idle thrust after top of descent (TOD), and then it controlled the avionics without human intervention. The test matrix varied aircraft weight, descent speed, and wind conditions. The first analysis in this paper determined the effect of the test matrix parameters on the FMS computation of TOD location, and it compared the results to those for the current ground predictor in the Efficient Descent Advisor (EDA). The second analysis was similar but considered the time to fly a specified distance to the meter fix. The effects of the test matrix variables together with the accuracy requirements for the predictor will determine the allowable error for the predictor inputs. For the B737, the EDA prediction of meter fix crossing time agreed well with the FMS; but its prediction of TOD location probably was not sufficiently accurate to enable idle-thrust descents in congested airspace, even though the FMS and EDA gave similar shapes for TOD location as a function of the test matrix variables. For the B777, the FMS and EDA gave different shapes for the TOD location function, and the EDA prediction of the TOD location is not accurate enough to fully enable the concept. Furthermore, the differences between the FMS and EDA predictions of meter fix crossing time for the B777 indicated that at least one of them was not sufficiently accurate.

  7. Preliminary Study of a Model Rotor in Descent

    NASA Technical Reports Server (NTRS)

    McAlister, K. W.; Tung, C.; Sharpe, D. L.; Huang, S.; Hendley, E. M.

    2000-01-01

    Within a program designed to develop experimental techniques for measuring the trajectory and structure of vortices trailing from the tips of rotor blades, the present preliminary study focuses on a method for quantifying the trajectory of the trailing vortex during descent flight conditions. This study also presents rotor loads and blade surface pressures for a range of tip-path plane angles and Mach numbers. Blade pressures near the leading edge and along the outer radius are compared with data obtained on the same model rotor, but in open jet facilities. A triangulation procedure based on two directable laser-light sheets, each containing an embedded reference, proved effective in defining the spatial coordinates of the trailing vortex. When interrogating a cross section of the flow that contains several trailing vortices, the greatest clarity was found to result when the flow is uniformly seeded. Surface pressure responses during blade-vortex interactions appeared equally sensitive near the leading edge and along the outer portion of the blade, but diminished rapidly as the distance along the blade chord increased. The pressure response was virtually independent of whether the tip-path plane angle was obtained through shaft tilt or cyclic pitch. Although the shape and frequency of the pressure perturbations on the advancing blade during blade-vortex interaction are similar to those obtained in open-jet facilities, the angle of the tip-path plane may need to be lower than the range covered in this study.

  8. Evolution and ecology of directed aerial descent in arboreal ants.

    PubMed

    Yanoviak, Stephen P; Munk, Yonatan; Dudley, Robert

    2011-12-01

    Directed aerial descent (DAD) is used by a variety of arboreal animals to escape predators, to remain in the canopy, and to access resources. Here, we build upon the discovery of DAD in ants of tropical canopies by summarizing its known phylogenetic distribution among ant genera, and within both the subfamily Pseudomyrmecinae and the genus Cephalotes. DAD has multiple evolutionary origins in ants, occurring independently in numerous genera in the subfamilies Myrmicinae, Formicinae, and Pseudomyrmecinae. Ablation experiments and video recordings of ants in a vertical wind tunnel showed that DAD in Cephalotes atratus is achieved via postural changes, specifically orientation of the legs and gaster. The occurrence of DAD in Formicinae indicates that the presence of a postpetiole is not essential for the behavior. Evidence to date indicates that gliding behavior is accomplished by visual targeting mediated by the compound eyes, and is restricted to diurnally active ants that nest in trees. Occlusion of ocelli in Pseudomyrmex gracilis workers had no effect on their success or performance in gliding. Experimental assessment of the fate of ants that fall to the understory showed that ants landing in water are 15 times more likely to suffer lethal attacks than are ants landing in leaf litter. Variation in both the aerodynamic mechanisms and selective advantages of DAD merits further study given the broad taxonomic diversity of arboreal ants that engage in this intriguing form of flight. PMID:21562023

  9. Physics-based Entry, Descent and Landing Risk Model

    NASA Technical Reports Server (NTRS)

    Gee, Ken; Huynh, Loc C.; Manning, Ted

    2014-01-01

    A physics-based risk model was developed to assess the risk associated with thermal protection system failures during the entry, descent and landing phase of a manned spacecraft mission. In the model, entry trajectories were computed using a three-degree-of-freedom trajectory tool, the aerothermodynamic heating environment was computed using an engineering-level computational tool and the thermal response of the TPS material was modeled using a one-dimensional thermal response tool. The model was capable of modeling the effect of micrometeoroid and orbital debris impact damage on the TPS thermal response. A Monte Carlo analysis was used to determine the effects of uncertainties in the vehicle state at Entry Interface, aerothermodynamic heating and material properties on the performance of the TPS design. The failure criterion was set as a temperature limit at the bondline between the TPS and the underlying structure. Both direct computation and response surface approaches were used to compute the risk. The model was applied to a generic manned space capsule design. The effect of material property uncertainty and MMOD damage on risk of failure were analyzed. A comparison of the direct computation and response surface approach was undertaken.

  10. Engineering description of the ascent/descent bet product

    NASA Technical Reports Server (NTRS)

    Seacord, A. W., II

    1986-01-01

    The Ascent/Descent output product is produced in the OPIP routine from three files which constitute its input. One of these, OPIP.IN, contains mission specific parameters. Meteorological data, such as atmospheric wind velocities, temperatures, and density, are obtained from the second file, the Corrected Meteorological Data File (METDATA). The third file is the TRJATTDATA file which contains the time-tagged state vectors that combine trajectory information from the Best Estimate of Trajectory (BET) filter, LBRET5, and Best Estimate of Attitude (BEA) derived from IMU telemetry. Each term in the two output data files (BETDATA and the Navigation Block, or NAVBLK) are defined. The description of the BETDATA file includes an outline of the algorithm used to calculate each term. To facilitate describing the algorithms, a nomenclature is defined. The description of the nomenclature includes a definition of the coordinate systems used. The NAVBLK file contains navigation input parameters. Each term in NAVBLK is defined and its source is listed. The production of NAVBLK requires only two computational algorithms. These two algorithms, which compute the terms DELTA and RSUBO, are described. Finally, the distribution of data in the NAVBLK records is listed.

  11. Minimum Landing Error Powered-Descent Guidance for Planetary Missions

    NASA Technical Reports Server (NTRS)

    Blackmore, Lars; Acikmese, Behcet

    2011-01-01

    An algorithm improves the accuracy with which a lander can be delivered to the surface of Mars. The main idea behind this innovation is the use of a lossless convexification, which converts an otherwise non-convex constraint related to thruster throttling to a convex constraint, enabling convex optimization to be used. The convexification leads directly to an algorithm that guarantees finding the global optimum of the original nonconvex optimization problem with a deterministic upper bound on the number of iterations required for convergence. In this innovation, previous work in powered-descent guidance using convex optimization is extended to handle the case where the lander must get as close as possible to the target given the available fuel, but is not required to arrive exactly at the target. The new algorithm calculates the minimum-fuel trajectory to the target, if one exists, and calculates the trajectory that minimizes the distance to the target if no solution to the target exists. This approach poses the problem as two Second-Order Cone Programs, which can be solved to global optimality with deterministic bounds on the number of iterations required.

  12. Mars Science Laboratory Entry, Descent, and Landing System Overview

    NASA Technical Reports Server (NTRS)

    Steltzner, Adam D.; Burkhart, P. Dan; Chen, Allen; Comeaux, Keith A.; Guernsey, Carl S.; Kipp, Devin M.; Lorenzoni, Leila V.; Mendeck, Gavin F.; Powell, Richard W.; Rivellini, Tommaso P.; San Martin, A. Miguel; Sell, Steven W.; Prakash, Ravi; Way, David W.

    2010-01-01

    In 2012, the Mars Science Laboratory (MSL) mission will pioneer the next generation of robotic Entry, Descent, and Landing (EDL) systems by delivering the largest and most capable rover to date to the surface of Mars. In addition to landing more mass than prior missions to Mars, MSL will offer access to regions of Mars that have been previously unreachable. The MSL EDL sequence is a result of a more stringent requirement set than any of its predecessors. Notable among these requirements is landing a 900 kg rover in a landing ellipse much smaller than that of any previous Mars lander. In meeting these requirements, MSL is extending the limits of the EDL technologies qualified by the Mars Viking, Mars Pathfinder, and Mars Exploration Rover missions. Thus, there are many design challenges that must be solved for the mission to be successful. Several pieces of the EDL design are technological firsts, such as guided entry and precision landing on another planet, as well as the entire Sky Crane maneuver. This paper discusses the MSL EDL architecture and discusses some of the challenges faced in delivering an unprecedented rover payload to the surface of Mars.

  13. Orion Entry, Descent, and Landing Performance and Mission Design

    NASA Technical Reports Server (NTRS)

    Broome, Joel M.; Johnson, Wyatt

    2007-01-01

    The Orion Vehicle is the next spacecraft to take humans into space and will include missions to ISS as well as missions to the Moon. As part of that challenge, the vehicle will have to accommodate multiple mission design concepts, since return from Low Earth Orbit and return from the Moon can be quite different. Commonality between the different missions as it relates to vehicle systems, guidance capability, and operations concepts is the goal. Several unique mission design concepts include the specification of multiple land-based landing sites for a vehicle with closed-loop direct and skip entry guidance, followed by a parachute descent and landing attenuation system. This includes the ability of the vehicle to accurately target and land at a designated landing site, including site location aspects, landing site size, and landing opportunities assessments. Analyses associated with these mission design and flight performance challenges and constraints will be discussed as well as potential operational concepts to provide feasibility and/or mission commonality.

  14. Race, language, and mental evolution in Darwin's descent of man.

    PubMed

    Alter, Stephen G

    2007-01-01

    Charles Darwin was notoriously ambiguous in his remarks about the relationship between human evolution and biological race. He stressed the original unity of the races, yet he also helped to popularize the notion of a racial hierarchy filling the gaps between the highest anthropoids and civilized Europeans. A focus on Darwin's explanation of how humans initially evolved, however, shows that he mainly stressed not hierarchy but a version of humanity's original mental unity. In his book The Descent of Man, Darwin emphasized a substantial degree of mental development (including the incipient use of language) in the early, monogenetic phase of human evolution. This development, he argued, necessarily came before primeval man's numerical increase, geographic dispersion, and racial diversification, because only thus could one explain how that group was able to spread at the expense of rival ape-like populations. This scenario stood opposed to a new evolutionary polygenism formulated in the wake of Darwin's Origin of Species by his ostensible supporters Alfred Russel Wallace and Ernst Haeckel. Darwin judged this outlook inadequate to the task of explaining humanity's emergence. PMID:17623873

  15. HLA Type Inference via Haplotypes Identical by Descent

    NASA Astrophysics Data System (ADS)

    Setty, Manu N.; Gusev, Alexander; Pe'Er, Itsik

    The Human Leukocyte Antigen (HLA) genes play a major role in adaptive immune response and are used to differentiate self antigens from non self ones. HLA genes are hyper variable with nearly every locus harboring over a dozen alleles. This variation plays an important role in susceptibility to multiple autoimmune diseases and needs to be matched on for organ transplantation. Unfortunately, HLA typing by serological methods is time consuming and expensive compared to high throughput Single Nucleotide Polymorphism (SNP) data. We present a new computational method to infer per-locus HLA types using shared segments Identical By Descent (IBD), inferred from SNP genotype data. IBD information is modeled as graph where shared haplotypes are explored among clusters of individuals with known and unknown HLA types to identify the latter. We analyze performance of the method in a previously typed subset of the HapMap population, achieving accuracy of 96% in HLA-A, 94% in HLA-B, 95% in HLA-C, 77% in HLA-DR1, 93% in HLA-DQA1 and 90% in HLA-DQB1 genes. We compare our method to a tag SNP based approach and demonstrate higher sensitivity and specificity. Our method demonstrates the power of using shared haplotype segments for large-scale imputation at the HLA locus.

  16. Identity by Descent in Island-Mainland Populations

    PubMed Central

    Rannala, B.; Hartigan, J. A.

    1995-01-01

    A new model is presented for the genetic structure among a collection of island populations, with fluctuating population sizes and continuous overlapping generations, using a stochastic birth, death and immigration (BDI) process. Immigrants enter each island from a large mainland population, with constant gene frequencies, according to a Poisson process. The average probability of identity by descent (IBD) for two haploid individuals randomly selected from an island population is f(0) = (?f(1) + ?)/(? + ?), where f(1) is the probability of IBD for two randomly selected immigrants, ? is the birth-rate for each individual, and ? is the arrival rate of immigrants into each island. The value of f(0) is independent of the death process, time and N. The expected level of genetic differentiation among island populations is F(ST) = (1 - 1/n)?/(? + ?), where n is the total number of islands receiving immigrants. Because f(0) and F(ST) are independent of the death process, for a BDI model, the population genetic structure for several general demographic situations may be examined using our equations. These include stochastic exponential, or logistic (regulated by death rate) growth within islands, or a ``source-sink'' population structure. Because the expected values of both f(0) and F(ST) are independent of time, these are achieved immediately, for a BDI model, with no need to assume the island populations are at genetic equilibrium. PMID:7598763

  17. Lunar Module Eagle Upon Descent to the Moon

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Carrying astronauts Neil A. Armstrong and Edwin E. Aldrin, Jr., the Lunar Module (LM) 'Eagle' was the first crewed vehicle to land on the Moon. The LM landed on the moon's surface on July 20, 1969 in the region known as Mare Tranquilitatis (the Sea of Tranquility). The LM is shown here making its descent to the lunar surface, while Astronaut Collins piloted the Command Module in a parking orbit around the Moon. The Apollo 11 mission launched from The Kennedy Space Center, Florida aboard a Saturn V launch vehicle on July 16, 1969 and safely returned to Earth on July 24, 1969. The 3-man crew aboard the flight consisted of Neil A. Armstrong, commander; Michael Collins, Command Module pilot; and Edwin E. Aldrin Jr., Lunar Module pilot. Armstrong was the first human to ever stand on the lunar surface. As he stepped off the LM, Armstrong proclaimed, 'That's one small step for man, one giant leap for mankind'. He was followed by Edwin (Buzz) Aldrin, describing the lunar surface as Magnificent desolation. The crew collected 47 pounds of lunar surface material which was returned to Earth for analysis. The surface exploration was concluded in 2˝ hours. With the success of Apollo 11, the national objective to land men on the Moon and return them safely to Earth had been accomplished. The Saturn V vehicle was developed by the Marshall Space Flight Center (MSFC) under the direction of Dr. von Braun.

  18. Cerebellar Transcranial Magnetic Stimulation: The Role of Coil Geometry and Tissue Depth?

    PubMed Central

    Hardwick, Robert M.; Lesage, Elise; Miall, R. Chris

    2014-01-01

    Background While transcranial magnetic stimulation (TMS) coil geometry has important effects on the evoked magnetic field, no study has systematically examined how different coil designs affect the effectiveness of cerebellar stimulation. Hypothesis The depth of the cerebellar targets will limit efficiency. Angled coils designed to stimulate deeper tissue are more effective in eliciting cerebellar stimulation. Methods Experiment 1 examined basic input–output properties of the figure-of-eight, batwing and double-cone coils, assessed with stimulation of motor cortex. Experiment 2 assessed the ability of each coil to activate cerebellum, using cerebellar-brain inhibition (CBI). Experiment 3 mapped distances from the scalp to cerebellar and motor cortical targets in a sample of 100 subjects' structural magnetic resonance images. Results Experiment 1 showed batwing and double-cone coils have significantly lower resting motor thresholds, and recruitment curves with steeper slopes than the figure-of-eight coil. Experiment 2 showed the double-cone coil was the most efficient for eliciting CBI. The batwing coil induced CBI only at higher stimulus intensities. The figure-of-eight coil did not elicit reliable CBI. Experiment 3 confirmed that cerebellar tissue is significantly deeper than primary motor cortex tissue, and we provide a map of scalp-to-target distances. Conclusions The double-cone and batwing coils designed to stimulate deeper tissue can effectively stimulate cerebellar targets. The double-cone coil was found to be most effective. The depth map provides a guide to the accessible regions of the cerebellar volume. These results can guide coil selection and stimulation parameters when designing cerebellar TMS studies. PMID:24924734

  19. Cerebellar Modulation of Frontal Cortex Dopamine Efflux in Mice: Relevance to Autism and Schizophrenia

    PubMed Central

    MITTLEMAN, GUY; GOLDOWITZ, DANIEL; HECK, DETLEF H.; BLAHA, CHARLES D.

    2013-01-01

    Cerebellar and frontal cortical pathologies have been commonly reported in schizophrenia, autism, and other developmental disorders. Whether there is a relationship between prefrontal and cerebellar pathologies is unknown. Using fixed potential amperometry, dopamine (DA) efflux evoked by cerebellar or, dentate nucleus electrical stimulation (50 Hz, 200 ?A) was recorded in prefrontal cortex of urethane anesthetized lurcher (Lc/+) mice with 100% loss of cerebellar Purkinje cells and wildtype (+/+) control mice. Cerebellar stimulation with 25 and 100 pulses evoked prefrontal cortex DA efflux in +/+ mice that persisted for 12 and 25 s poststimulation, respectively. In contrast, 25 pulse cerebellar stimulation failed to evoke prefrontal cortex DA efflux in Lc/+ mice indicating a dependency on cerebellar Purkinje cell outputs. Dentate nucleus stimulation (25 pulses) evoked a comparable but briefer (baseline recovery within 7 s) increase in prefrontal cortex DA efflux compared to similar cerebellar stimulation in +/+ mice. However, in Lc/+ mice 25 pulse dentate nucleus evoked prefrontal cortex DA efflux was attenuated by 60% with baseline recovery within 4 s suggesting that dentate nucleus outputs to prefrontal cortex remain partially functional. DA reuptake blockade enhanced 100 pulse stimulation evoked pre-frontal cortex responses, while serotonin or norepinephrine reuptake blockade were without effect indicating the specificity of the amperometric recordings to DA. Results provide neurochemical evidence that the cerebellum can modulate DA efflux in the prefrontal cortex. Together, these findings may explain why cerebellar and frontal cortical pathologies co-occur, and may provide a mechanism that accounts for the diversity of symptoms common to multiple developmental disorders. PMID:18435424

  20. [The effect of anthropometric factors on human cerebellar mass and its age dynamics].

    PubMed

    Stepanenko, A Iu

    2014-01-01

    The purpose of this work was to examine the dependence of human cerebellar mass and its age dynamics on the body length and body-build type. The study was carried out on 295 objects--the corpses of the individuals of both sexes (173 males and 122 females) who died at the age of 20-99 years. The length of the body, the transverse diameter of the chest and the cerebellar mass were measured. Somatotype was determined by the Rees-Eysenck index. It was found that human cerebellar mass ranged from 103 to 197 g (with the average of 144 ± 1.0 g) and was significantly greater in men than in women (150.5 ± 1.3 g vs. 133.9 ± 1.2 g, P < 0.001). Age affected cerebellar mass in men (R = -0.46) more, than in women (R = -0.43). In men, a period of relative stability of the cerebellar mass lasted up to about 50 years and then was followed by a period of its decrease. In women, the stable period was observed until approximately 70 years. The cerebellar mass was related to the body length (R = 0.35 for men and R = 0.36 for women). The dependence of the cerebellar mass on the body length was greater in men (1.0 g/cm) greater than in women (0.5 g/cm): with the increase of the body length the difference in the values of the cerebellar mass between men and women was found to grow. The cerebellar mass in the individuals with various body-build types was not significantly different PMID:25552081

  1. Qualitative and quantitative aspects of the microanatomy of the African elephant cerebellar cortex.

    PubMed

    Maseko, Busisiwe C; Jacobs, Bob; Spocter, Muhammad A; Sherwood, Chet C; Hof, Patrick R; Manger, Paul R

    2013-01-01

    The current study provides a number of novel observations on the organization and structure of the cerebellar cortex of the African elephant by using a combination of basic neuroanatomical and immunohistochemical stains with Golgi and stereologic analysis. While the majority of our observations indicate that the cerebellar cortex of the African elephant is comparable to other mammalian species, several features were unique to the elephant. The three-layered organization of the cerebellar cortex, the neuronal types and some aspects of the expression of calcium-binding proteins were common to a broad range of mammalian species. The Lugaro neurons observed in the elephant were greatly enlarged in comparison to those of other large-brained mammals, suggesting a possible alteration in the processing of neural information in the elephant cerebellar cortex. Analysis of Golgi impregnations indicated that the dendritic complexity of the different interneuron types was higher in elephants than other mammals. Expression of parvalbumin in the parallel fibers and calbindin expressed in the stellate and basket cells also suggested changes in the elephant cerebellar neuronal circuitry. The stereologic analysis confirmed and extended previous observations by demonstrating that neuronal density is low in the elephant cerebellar cortex, providing for a larger volume fraction of the neuropil. With previous results indicating that the elephants have the largest relative cerebellar size amongst mammals, and one of the absolutely largest mammalian cerebella, the current observations suggest that the elephants have a greater volume of a potentially more complexly organized cerebellar cortex compared to other mammals. This quantitatively larger and more complex cerebellar cortex likely represents part of the neural machinery required to control the complex motor patterns involved in movement of the trunk and the production of infrasonic vocalizations. PMID:23296570

  2. Metalinguistic deficits in patients with cerebellar dysfunction: empirical support for the dysmetria of thought theory.

    PubMed

    Guell, Xavier; Hoche, Franziska; Schmahmann, Jeremy D

    2015-02-01

    The cerebellar cognitive affective syndrome (CCAS) includes disruption of linguistic processing such as verbal fluency, verbal working memory, grammar, and speech perception. We set out to examine linguistic capabilities in patients with cerebellar lesions to determine which domains are spared and which impaired and to evaluate the underlying cognitive structure of these deficits. Forty-four patients with cerebellar disease were compared to 40 healthy controls on the Oral Sentence Production Test (OSPT) which assesses production of sentences with correct syntactic structure and semantic quality. Twenty-five of these cerebellar patients and 25 controls received the Test of Language Competence-Expanded (TLC-E) that assesses metalinguistic ability. The OSPT failed to reveal differences between patients and controls. In contrast, all cerebellar patients were impaired on each of the four TLC-E subtests. Differences between isolated cerebellar and complex cerebrocerebellar patients were nonsignificant. These results confirm and extend prior observations of the TLC-E in patients with cerebellar lesions and suggest three separate but related language impairments following cerebellar dysfunction: (1) disruption in automatic adjustment of intact grammatical and semantic abilities to a linguistic context in sentence production, (2) disruption in automatic adjustment to a linguistic context in sentence interpretation, and (3) disruption of cognitive processes essential for linguistic skills, such as analysis and sequential logical reasoning. These findings are consistent with the unifying framework of the universal cerebellar transform and the dysmetria of thought theory and provide new insights into the nature of the cognitive impairments in patients with the CCAS. PMID:25503825

  3. Restoring Cognitive Functions Using Non-Invasive Brain Stimulation Techniques in Patients with Cerebellar Disorders

    PubMed Central

    Pope, Paul A.; Miall, R. Chris

    2014-01-01

    Numerous studies have highlighted the possibility of modulating the excitability of cerebro–cerebellar circuits bi-directionally using transcranial electrical brain stimulation, in a manner akin to that observed using magnetic stimulation protocols. It has been proposed that cerebellar stimulation activates Purkinje cells in the cerebellar cortex, leading to inhibition of the dentate nucleus, which exerts a tonic facilitatory drive onto motor and cognitive regions of cortex through a synaptic relay in the ventral–lateral thalamus. Some cerebellar deficits present with cognitive impairments if damage to non-motor regions of the cerebellum disrupts the coupling with cerebral cortical areas for thinking and reasoning. Indeed, white matter changes in the dentato–rubral tract correlate with cognitive assessments in patients with Friedreich ataxia, suggesting that this pathway is one component of the anatomical substrate supporting a cerebellar contribution to cognition. An understanding of the physiology of the cerebro–cerebellar pathway previously helped us to constrain our interpretation of results from two recent studies in which we showed cognitive enhancements in healthy participants during tests of arithmetic after electrical stimulation of the cerebellum, but only when task demands were high. Others studies have also shown how excitation of the prefrontal cortex can enhance performance in a variety of working memory tasks. Thus, future efforts might be guided toward neuro-enhancement in certain patient populations, using what is commonly termed “non-invasive brain stimulation” as a cognitive rehabilitation tool to modulate cerebro–cerebellar circuits, or for stimulation over the cerebral cortex to compensate for decreased cerebellar drive to this region. This article will address these possibilities with a review of the relevant literature covering ataxias and cerebellar cognitive affective disorders, which are characterized by thalamo–cortical disturbances. PMID:24765079

  4. Intralimb and Interlimb Incoordination: Comparative Study between Patients with Parkinsonism and with Cerebellar Ataxia

    PubMed Central

    Asai, Yoshiyuki; Nomura, Taishin; Sato, Shunsuke; Inoue, Satoru; Mizukura, Isao; Yoneda, Toshihiko; Miki, Akinori; Sakoda, Saburo; Abe, Kazuo

    2005-01-01

    Dysfunction of limb coordination may be divided into two categories; intra and inter-limb incoordination. To make clear differential character in these two limb incoordination, we measured 13 patients mainly with cerebellar ataxia and 27 patients mainly with parkinsonism during pedaling of an ergometer with left and right pedals that can be rotated independently. As a result, interlimb incoordination was predominantly observed in patients with parkinsonism, while patients with cerebellar ataxia showed relatively preserved interlimb coordination but intralimb incoordination. We concluded that impairment of intralimb coordination was a character in patients with cerebellar ataxia, while impairment of interlimb coordination was a character in patients with parkinsonism.

  5. [Cerebellar gangliocytoma in an 11-year-old child].

    PubMed

    Joly, Marie; Valmary-Degano, Séverine; Cattin, Françoise; Vasiljevic, Alexandre; Jouvet, Anne; Viennet, Gabriel

    2014-12-01

    Cerebellar gangliocytoma can correspond to Lhermitte-Duclos disease, a benign hamartomatous malformation encountered in young adults. It can also be a part of gangliogliomas/gangliocytomas family, which usually encompasses temporal pediatric neoplasms associated with longstanding seizures. We report a case of a young 11-year-old patient who presented with a gangliocytoma of the cerebellum revealed by neurologic manifestations (headache, dyspraxia, equilibrium and gait disturbances). Diagnosis was made on surgical material. Tumour was characterized by dysplastic mature ganglion cells, perivascular lymphocytic infiltrates and no glial neoplastic component. By immunohistochemistry, ganglion cells expressed neurofilaments, MAP2 protein, synaptophysin, chromogranin A and S100 protein. BRAF V600E mutation was absent. Clinical characteristics, radiology, histopathology of the two main diagnoses are discussed. PMID:25499864

  6. Large cerebellar mass lesion: A rare intracranial manifestation of blastomycosis

    PubMed Central

    Munich, Stephan A.; Johnson, Andrew K.; Ahuja, Sumeet K.; Venizelos, Alexander; Byrne, Richard W.

    2013-01-01

    Background: Blastomyces dermatitidis is a dimorphic fungus found endemically in the Mississippi and Ohio River basins and in the Midwestern and Canadian provinces that border the Great Lakes. Unlike other fungal infections, it most commonly affects immunocompetent hosts. Blastomycosis typically manifests as pulmonary infection, but may affect nearly any organ, including the skin, bone, and genitourinary system. Central nervous system (CNS) blastomycosis is rare, but potentially fatal manifestation of this disease. When it does occur, it most commonly presents as acute or chronic meningitis. Case Description: We present a case of a patient who suffered intractable nausea and vomiting for several months before discovery of a large cerebellar blastomycoma causing mass effect and obstructive hydrocephalus. The enhancing lesion with unusual peripheral cystic structures is a unique radiographic appearance of CNS blastomycosis. Conclusion: We review this patient's purely intraparenchymal manifestation of CNS blastomycosis and describe the unique imaging characteristics encountered. PMID:24231945

  7. Memory trace and timing mechanism localized to cerebellar Purkinje cells.

    PubMed

    Johansson, Fredrik; Jirenhed, Dan-Anders; Rasmussen, Anders; Zucca, Riccardo; Hesslow, Germund

    2014-10-14

    The standard view of the mechanisms underlying learning is that they involve strengthening or weakening synaptic connections. Learned response timing is thought to combine such plasticity with temporally patterned inputs to the neuron. We show here that a cerebellar Purkinje cell in a ferret can learn to respond to a specific input with a temporal pattern of activity consisting of temporally specific increases and decreases in firing over hundreds of milliseconds without a temporally patterned input. Training Purkinje cells with direct stimulation of immediate afferents, the parallel fibers, and pharmacological blocking of interneurons shows that the timing mechanism is intrinsic to the cell itself. Purkinje cells can learn to respond not only with increased or decreased firing but also with an adaptively timed activity pattern. PMID:25267641

  8. Benign paroxysmal positioning vertigo with indeterminate cerebellar lesion: case report.

    PubMed

    Lynn, S; Brey, R

    1993-11-01

    Of the numerous causes of dizziness, those that represent a life-threatening condition are rare. Physicians must guard against missing these rare but serious conditions while controlling the cost of the evaluation of patients who present with dizziness. This case study involving a 41-year-old female was written to illustrate the importance of systematic case history taking and of obtaining an ENG. The patient presented with classic symptoms of benign paroxysmal positioning vertigo (BPPV). The managing physician performed an MRI, which showed a cerebellar lesion. Results of a biopsy were negative. The patient's symptoms persisted, and she travelled to our clinic for further assessment. An ENG demonstrated a classic response to the Dix-Hallpike maneuvers, and a canalith repositioning maneuver was performed. The positioning dizziness resolved, and when contacted several months later, the patient stated she had remained asymptomatic. PMID:8298174

  9. Memory trace and timing mechanism localized to cerebellar Purkinje cells

    PubMed Central

    Johansson, Fredrik; Jirenhed, Dan-Anders; Rasmussen, Anders; Hesslow, Germund

    2014-01-01

    The standard view of the mechanisms underlying learning is that they involve strengthening or weakening synaptic connections. Learned response timing is thought to combine such plasticity with temporally patterned inputs to the neuron. We show here that a cerebellar Purkinje cell in a ferret can learn to respond to a specific input with a temporal pattern of activity consisting of temporally specific increases and decreases in firing over hundreds of milliseconds without a temporally patterned input. Training Purkinje cells with direct stimulation of immediate afferents, the parallel fibers, and pharmacological blocking of interneurons shows that the timing mechanism is intrinsic to the cell itself. Purkinje cells can learn to respond not only with increased or decreased firing but also with an adaptively timed activity pattern. PMID:25267641

  10. Directional abnormalities of vestibular and optokinetic responses in cerebellar disease

    NASA Technical Reports Server (NTRS)

    Walker, M. F.; Zee, D. S.; Shelhamer, M. J. (Principal Investigator)

    1999-01-01

    Directional abnormalities of vestibular and optokinetic responses in patients with cerebellar degeneration are reported. Three-axis magnetic search-coil recordings of the eye and head were performed in eight cerebellar patients. Among these patients, examples of directional cross-coupling were found during (1) high-frequency, high-acceleration head thrusts; (2) constant-velocity chair rotations with the head fixed; (3) constant-velocity optokinetic stimulation; and (4) following repetitive head shaking. Cross-coupling during horizontal head thrusts consisted of an inappropriate upward eye-velocity component. In some patients, sustained constant-velocity yaw-axis chair rotations produced a mixed horizontal-torsional nystagmus and/or an increase in the baseline vertical slow-phase velocity. Following horizontal head shaking, some patients showed an increase in the slow-phase velocity of their downbeat nystagmus. These various forms of cross-coupling did not necessarily occur to the same degree in a given patient; this suggests that different mechanisms may be responsible. It is suggested that cross-coupling during head thrusts may reflect a loss of calibration of brainstem connections involved in the direct vestibular pathways, perhaps due to dysfunction of the flocculus. Cross-coupling during constant-velocity rotations and following head shaking may result from a misorientation of the angular eye-velocity vector in the velocity-storage system. Finally, responses to horizontal optokinetic stimulation included an inappropriate torsional component in some patients. This suggests that the underlying organization of horizontal optokinetic tracking is in labyrinthine coordinates. The findings are also consistent with prior animal-lesion studies that have shown a role for the vestibulocerebellum in the control of the direction of the VOR.

  11. Behavioral correlates of complex spike synchrony in cerebellar microzones.

    PubMed

    De Gruijl, Jornt R; Hoogland, Tycho M; De Zeeuw, Chris I

    2014-07-01

    The olivo-cerebellar system is crucial for smooth and well timed execution of movements based on sensory and proprioceptive cues. The inferior olive (IO) plays a pivotal role in this process by synchronizing its activity across neurons internally through connexin36 gap junctions and providing a timing and/or learning signal to the cerebellum. Even though synchrony achieved through electrical coupling in IO cells is generally thought to be important in timing motor output, a direct relation between timing of movement and synchrony of olivary discharges has never been demonstrated within functional microcomplexes using transgenics. Here we combined in vivo, two-photon calcium imaging of complex spikes in microcomplexes of Purkinje cell (PC) dendrites with high-speed filming of tail, trunk, and limb movements in awake wild-type and connexin36-deficient mice. In wild types at rest, functional clusters of PCs were poorly defined with synchrony correlations that were relatively small and spatially limited to mediolateral distances of ?50 ?m, whereas during locomotion synchrony of the same PCs increased in strength and extended over distances spanning multiple microzones that could be correlated to specific components of sharp and well bounded movements. Instead, connexin36-deficient mice exhibited prolonged and desynchronized complex spike activity within PC microcomplexes both at rest and during behavior. Importantly, the mutants also showed concomitant abnormalities in the execution of spinocerebellar reflexes, which were significantly slower and more gradual than in wild-type littermates, particularly following sensory perturbations. Our results highlight the importance of modulation of synchronous activity within and between cerebellar microcomplexes in on-line temporal processing of motor output. PMID:24990915

  12. [Cerebellar hemangioblastoma with marked pleomorphism: a case report].

    PubMed

    Ono, Takahiro; Sasajima, Toshio; Oda, Masaya; Mizoi, Kazuo

    2012-07-01

    We reported an extremely rare case of cerebellar hemangioblastoma with marked pleomorphism and reviewed the literature. A 68-year-old male presented with a one-month history of headache and vomiting. Neurological examination revealed right-sided dysmetria and truncal ataxia. Contrast-enhanced T1-weighted MR imaging revealed a heterogeneously enhancing tumor with solid and cystic components in the right cerebellum. The solid portion of the tumor was low intensity on diffusion-weighted imaging and low intensity on susceptibility-weighted imaging. 18F-fluorodeoxyglucose PET showed low uptake in the cerebellar tumor and the whole body examination was negative for malignancy. Vertebral angiogram demonstrated moderate tumor staining and no early filling veins. The patient underwent total removal of the tumor through suboccipital craniotomy. Microscopically, the solid tumor contained a cellular rich component consisting of stromal cells and a markedly pleomorphic component including atypical and multinucleated giant cells. The MIB-1 positive rate was 8.2%, which was slightly higher compared to that of hemangioblastomas. We observed strong staining for inhibin-?, aquaporin 1 and neuron specific enolase (NSE) in the tumor cells. PAX-2, cytokeratin and epithelial membrane antigen (EMA) were completely negative in the tumor cells, whereas the tumor cells demonstrated focal staining for CD10. The histological diagnosis was hemangioblastoma. Follow-up MR images showed no evidence of recurrent tumor 14 months after the resection. The study using a combination of immunohistochemical markers (e.g. inhibin-?, aquaporin 1 and PAX-2) is useful for differential diagnosis of hemangioblastoma from metastatic renal cell carcinoma. PMID:22728543

  13. Planning fuel-conservative descents in an airline environmental using a small programmable calculator: Algorithm development and flight test results

    NASA Technical Reports Server (NTRS)

    Knox, C. E.; Vicroy, D. D.; Simmon, D. A.

    1985-01-01

    A simple, airborne, flight-management descent algorithm was developed and programmed into a small programmable calculator. The algorithm may be operated in either a time mode or speed mode. The time mode was designed to aid the pilot in planning and executing a fuel-conservative descent to arrive at a metering fix at a time designated by the air traffic control system. The speed model was designed for planning fuel-conservative descents when time is not a consideration. The descent path for both modes was calculated for a constant with considerations given for the descent Mach/airspeed schedule, gross weight, wind, wind gradient, and nonstandard temperature effects. Flight tests, using the algorithm on the programmable calculator, showed that the open-loop guidance could be useful to airline flight crews for planning and executing fuel-conservative descents.

  14. Efficient clustering of identity-by-descent between multiple individuals

    PubMed Central

    Qian, Yu; Browning, Brian L.; Browning, Sharon R.

    2014-01-01

    Motivation: Most existing identity-by-descent (IBD) detection methods only consider haplotype pairs; less attention has been paid to considering multiple haplotypes simultaneously, even though IBD is an equivalence relation on haplotypes that partitions a set of haplotypes into IBD clusters. Multiple-haplotype IBD clusters may have advantages over pairwise IBD in some applications, such as IBD mapping. Existing methods for detecting multiple-haplotype IBD clusters are often computationally expensive and unable to handle large samples with thousands of haplotypes. Results: We present a clustering method, efficient multiple-IBD, which uses pairwise IBD segments to infer multiple-haplotype IBD clusters. It expands clusters from seed haplotypes by adding qualified neighbors and extends clusters across sliding windows in the genome. Our method is an order of magnitude faster than existing methods and has comparable performance with respect to the quality of clusters it uncovers. We further investigate the potential application of multiple-haplotype IBD clusters in association studies by testing for association between multiple-haplotype IBD clusters and low-density lipoprotein cholesterol in the Northern Finland Birth Cohort. Using our multiple-haplotype IBD cluster approach, we found an association with a genomic interval covering the PCSK9 gene in these data that is missed by standard single-marker association tests. Previously published studies confirm association of PCSK9 with low-density lipoprotein. Availability and implementation: Source code is available under the GNU Public License http://cs.au.dk/~qianyuxx/EMI/. Contact: qianyuxx@gmail.com Supplementary information: Supplementary data are available at Bioinformatics online. PMID:24363374

  15. GABAA Receptors of Cerebellar Granule Cells in Culture: Interaction with Benzodiazepines.

    PubMed

    Cupello, Aroldo; Di Braccio, Mario; Gatta, Elena; Grossi, Giancarlo; Nikas, Periklis; Pellistri, Francesca; Robello, Mauro

    2013-10-12

    GABAA receptor mediated inhibition plays an important role in modulating the input/output dynamics of cerebellum. A characteristic of cerebellar GABAA receptors is the presence in cerebellar granule cells of subunits such as ?6 and ? which give insensitivity to classical benzodiazepines. In fact, cerebellar GABAA receptors have generally been considered a poor model for testing drugs which potentially are active at the benzodiazepine site. In this overview we show how rat cerebellar granule cells in culture may be a useful model for studying new benzodiazepine site agonists. This is based on the pharmacological separation of diazepam-sensitive ?1 ?2/3 ?2 receptors from those which are diazepam-insensitive and contain the ?6 subunit. This is achieved by utilizing furosemide/Zn(2+) which block ?6 containing and incomplete receptors. PMID:24122079

  16. Translating cerebellar Purkinje neuron physiology to progress in dominantly inherited ataxia

    PubMed Central

    Chopra, Ravi; Shakkottai, Vikram G

    2014-01-01

    The cerebellum is an important structure for accurate control and timing of movement, and Purkinje neurons in the cerebellar cortex are key players in cerebellar motor control. Cerebellar dysfunction can result in ataxia, a disorder characterized by postural instability, gait disturbances and motor incoordination. Cerebellar ataxia is a symptom of a number of conditions, and the emerging evidence that Purkinje neuron dysfunction, in particular, abnormal Purkinje neuron repetitive firing, is a major driver of motor dysfunction in a subset of dominantly inherited ataxias is dicussed. Abnormalities in Purkinje neuron excitability that are observed in mouse models of each of these disorders, and where appropriate describe studies linking particular ion channels to aberrant excitability are also discussed. Common mechanisms of dysfunction and speculate about potential therapeutic targets, suggesting that Purkinje neuron firing abnormalities are a novel target for improving motor dysfunction in patients with some forms of dominantly inherited ataxia are proposed. PMID:25221437

  17. Surgical resection of cerebellar hemangioblastoma with enhanced wall thickness: A report of two cases

    PubMed Central

    SUN, ZHENXING; YUAN, DAN; SUN, YAXING; YAN, PENGXIANG; ZUO, HUANCONG

    2015-01-01

    Hemangioblastomas are tumors of the central nervous system, and the cerebellum is the most common site of occurrence. Cerebellar hemangioblastoma with enhanced wall thickness is rare and often misdiagnosed preoperatively. At present, no unified radiological classification system based on magnetic resonance imaging (MRI) findings exists for cerebellar hemangioblastoma, and this tumor type can be solid or cystic mass, according to the MRI findings. The most common presentation of cerebellar hemangioblastoma observed radiologically is a large sac with small nodules, where the wall of the large cyst is not enhanced. A tumor with enhanced large cysts and tumor nodules is extremely rare. The most effective treatment is complete resection of the cyst and the solid growth. The present case reports the successful treatment of two cases of cerebellar hemangioblastoma with enhanced wall thickness, including the MRI findings for the differential diagnoses and the surgical experiences.

  18. Cerebellar Morphology and Procedural Learning Impairment in Neuroleptic-Naive Youth at Ultrahigh Risk of Psychosis

    PubMed Central

    Dean, Derek J.; Bernard, Jessica A.; Orr, Joseph M.; Pelletier-Baldelli, Andrea; Gupta, Tina; Carol, Emily E.; Mittal, Vijay A.

    2014-01-01

    Despite evidence suggesting a role for cerebellar abnormalities in the pathogenesis of psychosis, the structure has yet to receive attention in individuals at ultrahigh risk for psychosis (UHR). Accumulating research has suggested that the cerebellum helps modulate cognition and movement, domains in which UHR individuals show impairment; understanding putative markers of risk, such as structural abnormalities and behavioral correlates, is essential. In this study, participants underwent a high-resolution structural brain scan and participated in a pursuit rotor experiment. Cerebellar regions associated with movement (anterior cerebellum) and cognition (crus I) were subsequently analyzed. UHR participants showed impaired performance on the pursuit rotor task, learned at a slower rate, and showed smaller cerebellar volumes compared with control participants. Left crus I volume was significantly associated with poor rate of learning. The present results suggest that cerebellar abnormalities and their behavioral correlates (poor learning and motor control) precede the onset of psychosis. PMID:25419496

  19. Traumatic basal subarachnoid hemorrhage suspected to have been caused by contrecoup cerebellar contusions: a case report.

    PubMed

    Sato, Takako; Tsuboi, Kento; Nomura, Masakatsu; Iwata, Misa; Abe, Shuntaro; Tamura, Akiyoshi; Tsuchihashi, Hitoshi; Nishio, Hajime; Suzuki, Koichi

    2014-03-01

    Traumatic cerebellar hemorrhagic contusions are infrequent, and the pathogenic mechanism involves a coup injury that is associated with motor vehicle accidents in most cases. Traumatic basal subarachnoid hemorrhage (TBSAH) is commonly reported after blunt trauma to the neck or unrestricted movement of the head, and the source of the hemorrhage is most frequently identified in the vertebrobasilar arteries. A 55-year-old woman who was addicted to alcohol was found dead in her bed. She had a bruise on the left side of her posterior parietal region, and autopsy revealed massive subarachnoid hemorrhage at the base of the brain; the hematoma was strongly attached to the right lower surface of the cerebellar hemisphere. No ruptured cerebral aneurysms, arteriovenous malformations or vertebrobasilar artery leakage were detected. Hemorrhagic cerebellar contusions were regarded as the source of the TBSAH. This is the first report of TBSAH suspected to have been caused by contrecoup cerebellar contusions. PMID:24411402

  20. Cerebellar Transcranial Direct Current Stimulation Impairs the Practice-dependent Proficiency Increase in Working Memory

    Microsoft Academic Search

    R. Ferrucci; S. Marceglia; M. Vergari; F. Cogiamanian; S. Mrakic-sposta; F. Mameli; S. Zago; S. Barbieri; A. Priori

    2008-01-01

    How the cerebellum is involved in the practice and proficiency of non-motor functions is still unclear. We tested whether transcranial direct current stimulation (tDCS) over the cerebellum (cerebellar tDCS) induces after-effects on the practice-dependent increase in the proficiency of a working memory (WM) task (Sternberg test) in 13 healthy subjects. We also assessed the effects of cerebellar tDCS on visual

  1. Evidence for a GABA-mediated cerebellar inhibition of the inferior olive in the cat

    Microsoft Academic Search

    G. Andersson; M. Garwicz; G. Hesslow

    1988-01-01

    1. Climbing fibres were activated by peripheral nerve stimulation at ‘high’ frequencies (>3 Hz) for 15–25 s and then at 0.9 Hz for about 1 min. The high frequency activation induced a post-conditioning inhibition, lasting up to about 1 min, of climbing fibre responses recorded from the cerebellar surface. 2. Electrolytic lesions were made in the superior cerebellar peduncle (brachium

  2. Characterization of the neuroprotective activity of rasagiline in cerebellar granule cells

    Microsoft Academic Search

    Dafna Bonneh-Barkay; Noam Ziv; John P. M. Finberg

    2005-01-01

    Rasagiline (N-propargyl-1-R-aminoindan) is a new selective inhibitor of MAO-B which is in development for the treatment of Parkinson's disease. The aim of the present study was to evaluate the neuroprotective properties of rasagiline and characterize the mechanism by which it exerts its neuroprotective effect in cerebellar granule cells. Cerebellar granule cells were prepared from 7 to 8 days postnatal Sprague-Dawley

  3. Palatal myoclonus induced by extirpation of a cerebellar astrocytoma. Case report.

    PubMed

    Nishigaya, K; Kaneko, M; Nagaseki, Y; Nukui, H

    1998-06-01

    A 45-year-old woman developed a rare case of palatal myoclonus with no other neurological signs after undergoing extirpation of a small cerebellar low-grade astrocytoma that was located in the right dentate nucleus. The palatal myoclonus has persisted for 4 years after the operation. Magnetic resonance T2-weighted imaging revealed a high-intensity lesion in the left inferior olive. Palatal myoclonus associated with the removal of cerebellar tumors is unusual but may easily be overlooked. PMID:9609309

  4. Do children with focal cerebellar lesions show deficits in shifting attention?

    PubMed

    Schoch, B; Gorissen, B; Richter, S; Ozimek, A; Kaiser, O; Dimitrova, A; Regel, J P; Wieland, R; Hövel, M; Gizewski, E; Timmann, D

    2004-09-01

    More recent findings suggest a possible role of the cerebellum in nonmotor functions. Disability of individuals with cerebellar damage in rapidly shifting attention is one frequently used example to support cerebellar involvement in mental skills. The original proposal was based on findings in five children with chronic surgical lesions of the cerebellum and a young adult with a degenerative disorder. The aim of the present study was to repeat Akshoomoff and Courchesne's initial findings in a larger group of children with focal cerebellar lesions. Ten children with cerebellar lesions and 10 age- and sex-matched controls were tested. Neocerebellar areas were affected in all children with cerebellar damage except one based on detailed analysis of MRI scans. Subjects had to perform a focus and a shift attention task. Two visual and two auditory stimuli were presented in a pseudorandom order. An ellipse and a high-pitched tone were presented less frequently than a circle and a low-pitched tone. Rare stimuli were presented at five different time intervals. In the focus tasks, subjects had to react to the same rare stimulus of one of the two modalities. In the shift task, subjects had to switch between the two rare stimuli. Motor deficits based on reaction times were small in cerebellar children compared with controls. The ability of target detection did not significantly differ in the children with cerebellar lesions compared with the control children in both the focus and the shift attention task. In particular, children with cerebellar damage showed no significant impairment in rapid (<2 s) shifts of attention. The present findings indicate that the cerebellum may be less critical in attention related processes than suggested previously. PMID:15115791

  5. Clinical signs of cerebellar dysfunction in schizophrenia, alcoholism, and their comorbidity

    Microsoft Academic Search

    Anjali Deshmukh; Margaret J Rosenbloom; Adolf Pfefferbaum; Edith V Sullivan

    2002-01-01

    Abnormalities of cerebellar structure and function, long recognized as a hallmark of chronic alcohol abuse, have also occasionally been noted in patients with schizophrenia. We used a four-point rating scale to assess clinical signs of cerebellar dysfunction in men meeting DSM-IV criteria for schizophrenia (N=34) and alcohol dependence (N=15) as well as normal control subjects (N=28). Compared to controls, alcoholics

  6. Labeling of the cerebellar peduncles using a supervised Gaussian classifier with volumetric tract segmentation

    NASA Astrophysics Data System (ADS)

    Ye, Chuyang; Bazin, Pierre-Louis; Bogovic, John A.; Ying, Sarah H.; Prince, Jerry L.

    2012-02-01

    The cerebellar peduncles are white matter tracts that play an important role in the communication of the cerebellum with other regions of the brain. They can be grouped into three fiber bundles: inferior cerebellar peduncle middle cerebellar peduncle, and superior cerebellar peduncle. Their automatic segmentation on diffusion tensor images would enable a better understanding of the cerebellum and would be less time-consuming and more reproducible than manual delineation. This paper presents a method that automatically labels the three fiber bundles based on the segmentatin results from the diffusion oriented tract segmentation (DOTS) algorithm, which achieves volume segmentation of white matter tracts using a Markov random field (MRF) framework. We use the DOTS labeling result as a guide to determine the classification of fibers produced by wild bootstrap probabilistic tractography. Mean distances from each fiber to each DOTS volume label are defined and then used as features that contribute to classification. A supervised Gaussian classifier is employed to label the fibers. Manually delineated cerebellar peduncles serve as training data to determine the parameters of class probabilities for each label. Fibers are labeled ad the class that has the highest posterior probability. An outlier detection ste[ re,pves fober tracts that belong to noise of that are not modeled by DOTS. Experiments show a successful classification of the cerebellar peduncles. We have also compared results between successive scans to demonstrate the reproducibility of the proposed method.

  7. Deregulated FGF and homeotic gene expression underlies cerebellar vermis hypoplasia in CHARGE syndrome

    PubMed Central

    Yu, Tian; Meiners, Linda C; Danielsen, Katrin; Wong, Monica TY; Bowler, Timothy; Reinberg, Danny; Scambler, Peter J; van Ravenswaaij-Arts, Conny MA; Basson, M Albert

    2013-01-01

    Mutations in CHD7 are the major cause of CHARGE syndrome, an autosomal dominant disorder with an estimated prevalence of 1/15,000. We have little understanding of the disruptions in the developmental programme that underpin brain defects associated with this syndrome. Using mouse models, we show that Chd7 haploinsufficiency results in reduced Fgf8 expression in the isthmus organiser (IsO), an embryonic signalling centre that directs early cerebellar development. Consistent with this observation, Chd7 and Fgf8 loss-of-function alleles interact during cerebellar development. CHD7 associates with Otx2 and Gbx2 regulatory elements and altered expression of these homeobox genes implicates CHD7 in the maintenance of cerebellar identity during embryogenesis. Finally, we report cerebellar vermis hypoplasia in 35% of CHARGE syndrome patients with a proven CHD7 mutation. These observations provide key insights into the molecular aetiology of cerebellar defects in CHARGE syndrome and link reduced FGF signalling to cerebellar vermis hypoplasia in a human syndrome. DOI: http://dx.doi.org/10.7554/eLife.01305.001 PMID:24368733

  8. Compartmentation of the cerebellar cortex in the naked mole-rat (Heterocephalus glaber).

    PubMed

    Marzban, Hassan; Hoy, Nathan; Aavani, Tooka; Sarko, Diana K; Catania, Kenneth C; Hawkes, Richard

    2011-09-01

    Despite the apparent uniformity in cellular composition of the adult mammalian cerebellar cortex, it is actually highly compartmentalized into transverse zones and within each zone further subdivided into a reproducible array of parasagittal stripes. This basic cerebellar architecture is highly conserved in birds and mammals. However, different species have very different cerebellar morphologies, and it is unclear if cerebellar architecture reflects taxonomic relations or ecological niches. To explore this, we have examined the cerebellum of the naked mole-rat Heterocephalus glaber, a burrowing rodent with adaptations to a subterranean life that include only a rudimentary visual system. The cerebellum of H. glaber resembles that of other rodents with the remarkable exception that cerebellar regions that are prominent in the handling of visual information (the central zone, nodular zone, and dorsal paraflocculus) are greatly reduced or absent. In addition, there is a notable increase in size in the posterior zone, consistent with an expanded role for the trigeminal somatosensory system. These data suggest that cerebellar architecture may be substantially modified to serve a particular ecological niche. PMID:21298580

  9. Cerebellar dysfunction in progressive supranuclear palsy: a transcranial magnetic stimulation study.

    PubMed

    Shirota, Yuichiro; Hamada, Masashi; Hanajima, Ritsuko; Terao, Yasuo; Matsumoto, Hideyuki; Ohminami, Shinya; Tsuji, Shoji; Ugawa, Yoshikazu

    2010-10-30

    Progressive supranuclear palsy (PSP) rarely shows cerebellar signs and symptoms even though the cerebellar dentate nuclei are involved pathologically. This study evaluates cerebellar function using transcranial magnetic stimulation (TMS) to determine whether subclinical cerebellar involvement is present in PSP patients. We studied 11 patients with PSP, 11 patients with Parkinson's disease (PD), and 10 age-matched controls. Patients were examined with their usual medications and in their relative on state. Motor evoked potentials (MEPs) were recorded from the hand muscle. Cerebellar function was evaluated using suppressive effects of TMS over the cerebellum on MEPs elicited by TMS over the contralateral motor cortex, which we call cerebellar inhibition (CBI). Interstimulus intervals (ISIs) of 4 to 8 ms were used, and the time course of CBI was analyzed. The CBI was reduced in PSP patients. By contrast, the CBI was normal in PD patients in their on state. Although the CBI in their off state should be examined in future studies, the results described herein suggest that Purkinje cells or the dentato-thalamo-cortical pathway assessed by CBI is involved in PSP. Our results are compatible with the pathological findings showing severe dentate nucleus degeneration in PSP patients. PMID:20818672

  10. Population-based study of acquired cerebellar ataxia in Al-Kharga district, New Valley, Egypt

    PubMed Central

    Farghaly, Wafaa MA; El-Tallawy, Hamdy N; Shehata, Ghaydaa A; Rageh, Tarek A; Hakeem, Nabil Abdel; Abo-Elfetoh, Noha M

    2011-01-01

    Background: The aim of this research was to determine the prevalence and etiology of acquired ataxia in Al-Kharga district, New Valley, Egypt. Methods: A population-based study of acquired ataxia was conducted in a defined geographical region with a total population of 62,583. A door-to-door survey was used to identify cases of acquired cerebellar ataxia. Patients with acquired cerebellar ataxia at any age and of both genders were included. Cases of known inherited cerebellar ataxia, acquired neurological disorders with ataxia as a minor feature, or pure acquired sensory ataxia, were excluded. Results: We identified 17 cases of acquired ataxia, of which eight were vascular, six were an ataxic cerebral palsy subtype, and three involved postencephalitic ataxia. The crude prevalence rate for acquired ataxia was 27.16/100,000 (95% confidence interval [CI]: 14.3–40.1). The mean age of the patients at interview was 31.8 (range 4–72) years, with a male to female ratio of 2.1:1. The most frequent presenting complaint was disturbance of gait (90.7%). The majority (92%) were ambulatory, but only 9.3% were independently self-caring. Conclusion: This population-based study provides an insight into acquired cerebellar ataxia within a defined region, and may inform decisions about the rational use of health care resources for patients with acquired cerebellar ataxia. The most common causes of acquired cerebellar ataxia in this region were cerebrovascular injury and cerebral palsy. PMID:21552320

  11. Neurogenin 2 regulates progenitor cell-cycle progression and Purkinje cell dendritogenesis in cerebellar development

    PubMed Central

    Florio, Marta; Leto, Ketty; Muzio, Luca; Tinterri, Andrea; Badaloni, Aurora; Croci, Laura; Zordan, Paola; Barili, Valeria; Albieri, Ilaria; Guillemot, François; Rossi, Ferdinando; Consalez, G. Giacomo

    2012-01-01

    By serving as the sole output of the cerebellar cortex, integrating a myriad of afferent stimuli, Purkinje cells (PCs) constitute the principal neuron in cerebellar circuits. Several neurodegenerative cerebellar ataxias feature a selective cell-autonomous loss of PCs, warranting the development of regenerative strategies. To date, very little is known as to the regulatory cascades controlling PC development. During central nervous system development, the proneural gene neurogenin 2 (Neurog2) contributes to many distinct neuronal types by specifying their fate and/or dictating development of their morphological features. By analyzing a mouse knock-in line expressing Cre recombinase under the control of Neurog2 cis-acting sequences we show that, in the cerebellar primordium, Neurog2 is expressed by cycling progenitors cell-autonomously fated to become PCs, even when transplanted heterochronically. During cerebellar development, Neurog2 is expressed in G1 phase by progenitors poised to exit the cell cycle. We demonstrate that, in the absence of Neurog2, both cell-cycle progression and neuronal output are significantly affected, leading to an overall reduction of the mature cerebellar volume. Although PC fate identity is correctly specified, the maturation of their dendritic arbor is severely affected in the absence of Neurog2, as null PCs develop stunted and poorly branched dendrites, a defect evident from the early stages of dendritogenesis. Thus, Neurog2 represents a key regulator of PC development and maturation. PMID:22669821

  12. Fluorodeoxyglucose positron emission tomography/computed tomography findings in a patient with cerebellar mutism after operation in posterior fossa.

    PubMed

    Gedik, Gonca Kara; Sari, Oktay; Köktekir, Ender; Akdemir, Gökhan

    2014-03-17

    Cerebellar mutism is a transient period of speechlessness that evolves after posterior fossa surgery in children. Although direct cerebellar and brain stem injury and supratentorial dysfunction have been implicated in the mediation of mutism, the pathophysiological mechanisms involved in the evolution of this kind of mutism remain unclear. Magnetic resonance imaging revealed dentatothalamocortical tract injuries and single photon emission computed tomography showed cerebellar and cerebral hypoperfusion in patients with cerebellar mutism. However, findings with (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) in this group of patients have not been documented previously. In this clinical case, we report a patient who experienced cerebellar mutism after undergoing a posterior fossa surgery. Right cerebellar and left frontal lobe hypometabolism was shown using FDG PET/CT. The FDG metabolism of both the cerebellum and the frontal lobe returned to normal levels after the resolution of the mutism symptoms. PMID:24650725

  13. Global Patterns of Prostate Cancer Incidence, Aggressiveness, and Mortality in Men of African Descent

    PubMed Central

    Rebbeck, Timothy R.; Devesa, Susan S.; Chang, Bao-Li; Bunker, Clareann H.; Cheng, Iona; Cooney, Kathleen; Eeles, Rosalind; Fernandez, Pedro; Giri, Veda N.; Gueye, Serigne M.; Haiman, Christopher A.; Henderson, Brian E.; Heyns, Chris F.; Hu, Jennifer J.; Ingles, Sue Ann; Isaacs, William; Jalloh, Mohamed; John, Esther M.; Kibel, Adam S.; Kidd, LaCreis R.; Layne, Penelope; Leach, Robin J.; Neslund-Dudas, Christine; Okobia, Michael N.; Ostrander, Elaine A.; Park, Jong Y.; Patrick, Alan L.; Phelan, Catherine M.; Ragin, Camille; Roberts, Robin A.; Rybicki, Benjamin A.; Stanford, Janet L.; Strom, Sara; Thompson, Ian M.; Witte, John; Xu, Jianfeng; Yeboah, Edward; Hsing, Ann W.; Zeigler-Johnson, Charnita M.

    2013-01-01

    Prostate cancer (CaP) is the leading cancer among men of African descent in the USA, Caribbean, and Sub-Saharan Africa (SSA). The estimated number of CaP deaths in SSA during 2008 was more than five times that among African Americans and is expected to double in Africa by 2030. We summarize publicly available CaP data and collected data from the men of African descent and Carcinoma of the Prostate (MADCaP) Consortium and the African Caribbean Cancer Consortium (AC3) to evaluate CaP incidence and mortality in men of African descent worldwide. CaP incidence and mortality are highest in men of African descent in the USA and the Caribbean. Tumor stage and grade were highest in SSA. We report a higher proportion of T1 stage prostate tumors in countries with greater percent gross domestic product spent on health care and physicians per 100,000 persons. We also observed that regions with a higher proportion of advanced tumors reported lower mortality rates. This finding suggests that CaP is underdiagnosed and/or underreported in SSA men. Nonetheless, CaP incidence and mortality represent a significant public health problem in men of African descent around the world. PMID:23476788

  14. Advances in POST2 End-to-End Descent and Landing Simulation for the ALHAT Project

    NASA Technical Reports Server (NTRS)

    Davis, Jody L.; Striepe, Scott A.; Maddock, Robert W.; Hines, Glenn D.; Paschall, Stephen, II; Cohanim, Babak E.; Fill, Thomas; Johnson, Michael C.; Bishop, Robert H.; DeMars, Kyle J.; Sostaric, Ronald r.; Johnson, Andrew E.

    2008-01-01

    Program to Optimize Simulated Trajectories II (POST2) is used as a basis for an end-to-end descent and landing trajectory simulation that is essential in determining design and integration capability and system performance of the lunar descent and landing system and environment models for the Autonomous Landing and Hazard Avoidance Technology (ALHAT) project. The POST2 simulation provides a six degree-of-freedom capability necessary to test, design and operate a descent and landing system for successful lunar landing. This paper presents advances in the development and model-implementation of the POST2 simulation, as well as preliminary system performance analysis, used for the testing and evaluation of ALHAT project system models.

  15. Multi-perturbation stochastic parallel gradient descent method for wavefront correction.

    PubMed

    Wu, Kenan; Sun, Yang; Huai, Ying; Jia, Shuqin; Chen, Xi; Jin, Yuqi

    2015-02-01

    The multi-perturbation stochastic parallel gradient descent (SPGD) method for adaptive optics is presented in this work. The method is based on a new architecture. The incoming beam with distorted wavefront is split into N sub-beams. Each sub-beam is modulated by a wavefront corrector and its performance metric is measured subsequently. Adaptive system based on the multi-perturbation SPGD can operate in two modes - the fast descent mode and the modal basis updating mode. Control methods of the two operation modes are given. Experiments were carried out to prove the effectiveness of the proposed method. Analysis as well as experimental results showed that the two operation modes of the multi-perturbation SPGD enhance the conventional SPGD in different ways. The fast descent mode provides faster convergence than the conventional SPGD. The modal basis updating mode can optimize the modal basis set for SPGD with global coupling. PMID:25836154

  16. Descent and Landing Triggers for the Orion Multi-Purpose Crew Vehicle Exploration Flight Test-1

    NASA Technical Reports Server (NTRS)

    Bihari, Brian D.; Semrau, Jeffrey D.; Duke, Charity J.

    2013-01-01

    The Orion Multi-Purpose Crew Vehicle (MPCV) will perform a flight test known as Exploration Flight Test-1 (EFT-1) currently scheduled for 2014. One of the primary functions of this test is to exercise all of the important Guidance, Navigation, Control (GN&C), and Propulsion systems, along with the flight software for future flights. The Descent and Landing segment of the flight is governed by the requirements levied on the GN&C system by the Landing and Recovery System (LRS). The LRS is a complex system of parachutes and flight control modes that ensure that the Orion MPCV safely lands at its designated target in the Pacific Ocean. The Descent and Landing segment begins with the jettisoning of the Forward Bay Cover and concludes with sensing touchdown. This paper discusses the requirements, design, testing, analysis and performance of the current EFT-1 Descent and Landing Triggers flight software.

  17. Preliminary assessment of the Mars Science Laboratory entry, descent, and landing simulation

    NASA Astrophysics Data System (ADS)

    Way, David W.

    On August 5, 2012, the Mars Science Laboratory rover, Curiosity, successfully landed inside Gale Crater. This landing was the seventh successful landing and fourth rover to be delivered to Mars. Weighing nearly one metric ton, Curiosity is the largest and most complex rover ever sent to investigate another planet. Safely landing such a large payload required an innovative Entry, Descent, and Landing system, which included the first guided entry at Mars, the largest supersonic parachute ever flown at Mars, and the novel Sky Crane landing system. A complete, end-to-end, six degree-of-freedom, multi-body computer simulation of the Mars Science Laboratory Entry, Descent, and Landing sequence was developed at the NASA Langley Research Center. In-flight data gathered during the successful landing is compared to pre-flight statistical distributions, predicted by the simulation. These comparisons provide insight into both the accuracy of the simulation and the overall performance of the Entry, Descent, and Landing system.

  18. Evolutionary analyses of non-genealogical bonds produced by introgressive descent.

    PubMed

    Bapteste, Eric; Lopez, Philippe; Bouchard, Frédéric; Baquero, Fernando; McInerney, James O; Burian, Richard M

    2012-11-01

    All evolutionary biologists are familiar with evolutionary units that evolve by vertical descent in a tree-like fashion in single lineages. However, many other kinds of processes contribute to evolutionary diversity. In vertical descent, the genetic material of a particular evolutionary unit is propagated by replication inside its own lineage. In what we call introgressive descent, the genetic material of a particular evolutionary unit propagates into different host structures and is replicated within these host structures. Thus, introgressive descent generates a variety of evolutionary units and leaves recognizable patterns in resemblance networks. We characterize six kinds of evolutionary units, of which five involve mosaic lineages generated by introgressive descent. To facilitate detection of these units in resemblance networks, we introduce terminology based on two notions, P3s (subgraphs of three nodes: A, B, and C) and mosaic P3s, and suggest an apparatus for systematic detection of introgressive descent. Mosaic P3s correspond to a distinct type of evolutionary bond that is orthogonal to the bonds of kinship and genealogy usually examined by evolutionary biologists. We argue that recognition of these evolutionary bonds stimulates radical rethinking of key questions in evolutionary biology (e.g., the relations among evolutionary players in very early phases of evolutionary history, the origin and emergence of novelties, and the production of new lineages). This line of research will expand the study of biological complexity beyond the usual genealogical bonds, revealing additional sources of biodiversity. It provides an important step to a more realistic pluralist treatment of evolutionary complexity. PMID:23090996

  19. Evolutionary analyses of non-genealogical bonds produced by introgressive descent

    PubMed Central

    Bapteste, Eric; Lopez, Philippe; Bouchard, Frédéric; Baquero, Fernando; McInerney, James O.; Burian, Richard M.

    2012-01-01

    All evolutionary biologists are familiar with evolutionary units that evolve by vertical descent in a tree-like fashion in single lineages. However, many other kinds of processes contribute to evolutionary diversity. In vertical descent, the genetic material of a particular evolutionary unit is propagated by replication inside its own lineage. In what we call introgressive descent, the genetic material of a particular evolutionary unit propagates into different host structures and is replicated within these host structures. Thus, introgressive descent generates a variety of evolutionary units and leaves recognizable patterns in resemblance networks. We characterize six kinds of evolutionary units, of which five involve mosaic lineages generated by introgressive descent. To facilitate detection of these units in resemblance networks, we introduce terminology based on two notions, P3s (subgraphs of three nodes: A, B, and C) and mosaic P3s, and suggest an apparatus for systematic detection of introgressive descent. Mosaic P3s correspond to a distinct type of evolutionary bond that is orthogonal to the bonds of kinship and genealogy usually examined by evolutionary biologists. We argue that recognition of these evolutionary bonds stimulates radical rethinking of key questions in evolutionary biology (e.g., the relations among evolutionary players in very early phases of evolutionary history, the origin and emergence of novelties, and the production of new lineages). This line of research will expand the study of biological complexity beyond the usual genealogical bonds, revealing additional sources of biodiversity. It provides an important step to a more realistic pluralist treatment of evolutionary complexity. PMID:23090996

  20. A Task-Analytic Approach to the Determination of Training Requirements for the Precision Descent

    NASA Technical Reports Server (NTRS)

    Smith, Nancy; Rosekind, Mark (Technical Monitor)

    1996-01-01

    A task-analytic approach was used to evaluate the results from an experiment comparing two training methods for the "Precision Descent," a cockpit procedure designed to complement a new, computer-based air traffic control advisory system by allowing air traffic controllers to assign precise descent trajectories to aircraft. A task model was developed for the procedure using a methodology that represents four different categories of task-related knowledge: (1) ability to determine current flight goals; (2) ability to assess the current flight situation relative to those goals; (3) operational knowledge about flight-related tasks; and (4) knowledge about task selection. This model showed what knowledge experienced pilots already possessed, and how that knowledge was supplemented by training material provided in the two training conditions. All flight crews were given a "Precision Descent Chart" that explained the procedure's clearances and compliance requirements. This information enabled pilots to establish appropriate flight goals for the descent, and to monitor their compliance with those goals. In addition to this chart, half of the crews received a "Precision Descent Bulletin" containing technique recommendations for performing procedure-related tasks. The Bulletin's recommendations supported pilots in task selection and helped clarify the procedure's compliance requirements. Eight type-rated flight crews flew eight Precision Descents in a Boeing 747-400 simulator, with four crews in each of the two training conditions. Both conditions (Chart and Chart-with-Bulletin) relied exclusively on the use of those documents to introduce the procedure. No performance feedback was provided during the experiment. Preliminary result show better procedure compliance and higher acceptability ratings from flight crews in the Chart-with-Bulletin condition. These crews performed flight-related tasks less efficiently, however, using the simpler but less efficient methods suggested in the Bulletin. When a more efficient method was recognized, these crews tended to use the more efficient method in addition to the Bulletin's recommendation, instead of replacing it.

  1. Comparative neuronal morphology of the cerebellar cortex in afrotherians, carnivores, cetartiodactyls, and primates.

    PubMed

    Jacobs, Bob; Johnson, Nicholas L; Wahl, Devin; Schall, Matthew; Maseko, Busisiwe C; Lewandowski, Albert; Raghanti, Mary A; Wicinski, Bridget; Butti, Camilla; Hopkins, William D; Bertelsen, Mads F; Walsh, Timothy; Roberts, John R; Reep, Roger L; Hof, Patrick R; Sherwood, Chet C; Manger, Paul R

    2014-01-01

    Although the basic morphological characteristics of neurons in the cerebellar cortex have been documented in several species, virtually nothing is known about the quantitative morphological characteristics of these neurons across different taxa. To that end, the present study investigated cerebellar neuronal morphology among eight different, large-brained mammalian species comprising a broad phylogenetic range: afrotherians (African elephant, Florida manatee), carnivores (Siberian tiger, clouded leopard), cetartiodactyls (humpback whale, giraffe) and primates (human, common chimpanzee). Specifically, several neuron types (e.g., stellate, basket, Lugaro, Golgi, and granule neurons; N = 317) of the cerebellar cortex were stained with a modified rapid Golgi technique and quantified on a computer-assisted microscopy system. There was a 64-fold variation in brain mass across species in our sample (from clouded leopard to the elephant) and a 103-fold variation in cerebellar volume. Most dendritic measures tended to increase with cerebellar volume. The cerebellar cortex in these species exhibited the trilaminate pattern common to all mammals. Morphologically, neuron types in the cerebellar cortex were generally consistent with those described in primates (Fox et al., 1967) and rodents (Palay and Chan-Palay, 1974), although there was substantial quantitative variation across species. In particular, Lugaro neurons in the elephant appeared to be disproportionately larger than those in other species. To explore potential quantitative differences in dendritic measures across species, MARSplines analyses were used to evaluate whether species could be differentiated from each other based on dendritic characteristics alone. Results of these analyses indicated that there were significant differences among all species in dendritic measures. PMID:24795574

  2. Comparative neuronal morphology of the cerebellar cortex in afrotherians, carnivores, cetartiodactyls, and primates

    PubMed Central

    Jacobs, Bob; Johnson, Nicholas L.; Wahl, Devin; Schall, Matthew; Maseko, Busisiwe C.; Lewandowski, Albert; Raghanti, Mary A.; Wicinski, Bridget; Butti, Camilla; Hopkins, William D.; Bertelsen, Mads F.; Walsh, Timothy; Roberts, John R.; Reep, Roger L.; Hof, Patrick R.; Sherwood, Chet C.; Manger, Paul R.

    2014-01-01

    Although the basic morphological characteristics of neurons in the cerebellar cortex have been documented in several species, virtually nothing is known about the quantitative morphological characteristics of these neurons across different taxa. To that end, the present study investigated cerebellar neuronal morphology among eight different, large-brained mammalian species comprising a broad phylogenetic range: afrotherians (African elephant, Florida manatee), carnivores (Siberian tiger, clouded leopard), cetartiodactyls (humpback whale, giraffe) and primates (human, common chimpanzee). Specifically, several neuron types (e.g., stellate, basket, Lugaro, Golgi, and granule neurons; N = 317) of the cerebellar cortex were stained with a modified rapid Golgi technique and quantified on a computer-assisted microscopy system. There was a 64-fold variation in brain mass across species in our sample (from clouded leopard to the elephant) and a 103-fold variation in cerebellar volume. Most dendritic measures tended to increase with cerebellar volume. The cerebellar cortex in these species exhibited the trilaminate pattern common to all mammals. Morphologically, neuron types in the cerebellar cortex were generally consistent with those described in primates (Fox et al., 1967) and rodents (Palay and Chan-Palay, 1974), although there was substantial quantitative variation across species. In particular, Lugaro neurons in the elephant appeared to be disproportionately larger than those in other species. To explore potential quantitative differences in dendritic measures across species, MARSplines analyses were used to evaluate whether species could be differentiated from each other based on dendritic characteristics alone. Results of these analyses indicated that there were significant differences among all species in dendritic measures. PMID:24795574

  3. Preliminary evidence of an effect of cerebellar volume on postural sway in FMR1 premutation males.

    PubMed

    Birch, R C; Hocking, D R; Cornish, K M; Menant, J C; Georgiou-Karistianis, N; Godler, D E; Wen, W; Hackett, A; Rogers, C; Trollor, J N

    2015-03-01

    Recent evidence suggests that early changes in postural control may be discernible among females with premutation expansions (55-200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene at risk of developing fragile X-associated tremor ataxia syndrome (FXTAS). Cerebellar dysfunction is well described in males and females with FXTAS, yet the interrelationships between cerebellar volume, CGG repeat length, FMR1 messenger RNA (mRNA) levels and changes in postural control remain unknown. This study examined postural sway during standing in a cohort of 22 males with the FMR1 premutation (ages 26-80) and 24 matched controls (ages 26-77). The influence of cerebellar volume, CGG repeat length and FMR1 mRNA levels on postural sway was explored using multiple linear regression. The results provide preliminary evidence that increasing CGG repeat length and decreasing cerebellar volume were associated with greater postural sway among premutation males. The relationship between CGG repeat length and postural sway was mediated by a negative association between CGG repeat size and cerebellar volume. While FMR1 mRNA levels were significantly elevated in the premutation group and correlated with CGG repeat length, FMR1 mRNA levels were not significantly associated with postural sway scores. These findings show for the first time that greater postural sway among males with the FMR1 premutation may reflect CGG repeat-mediated disruption in vulnerable cerebellar circuits implicated in postural control. However, longitudinal studies in larger samples are required to confirm whether the relationships between cerebellar volume, CGG repeat length and postural sway indicate greater risk for neurological decline. PMID:25689687

  4. Sensitivity studies of 4D descent strategies in an advanced metering environment

    NASA Technical Reports Server (NTRS)

    Izumi, K. H.

    1986-01-01

    An investigation of utilizing various 4D airplane descent strategies in an advanced time-based metering environment was conducted. The three strategies considered were clean-idle Mach/CAS, constant flight path angle (CFPA) Mach/CAS, and fuel-optimal. Traffic inputs consisted of all combinatory pairs of three types of commercial turbojets (B737-300, B747-200, and B767-200) and two weight classes for each airplane type. Sensitivities of traffic throughput and fleet fuel to descent strategies, both among themselves and in combination, for different assigned meter fix times and traffic pairings were studied under controlled initial conditions.

  5. Initial Field Evaluation of Pilot Procedures for Flying CTAS Descent Clearances

    NASA Technical Reports Server (NTRS)

    Palmer, Everett; Goka, Tsuyoshi; Cashion, Patricia; Feary, Michael; Graham, Holly; Smith, Nancy; Shafto, Michael (Technical Monitor)

    1994-01-01

    The Center TRACON Automation System (CTAS) is a new support system that is designed to assist air traffic controllers in the management of arrival traffic. CTAS will provide controllers with more information about current air traffic, enabling them to provide clearances for efficient, conflict-free descents that help achieve an orderly stream of aircraft at the final approach fix. CTAS is a computer-based system that functions as a "ground-based FMS" that can predict flight trajectories and arrival times for all incoming aircraft. CTAS uses an aircraft's cruise airspeed; current air traffic, winds and temperature; performance characteristics of the aircraft type; and individual airline preferences to create a flight profile from cruise altitude to the final approach fix. Controllers can use this flight profile to provide a descent clearance that will allow an aircraft to fly an efficient descent and merge more smoothly with other arriving aircraft. A field test of the CTAS Descent Advisor software was conducted at the Denver Center for aircraft arriving at the Stapleton International Airport from September 12-29. CTAS Descent clearances were given to a NASA flight test aircraft and to 77 airline flights that arrived during low traffic periods. For the airline portion of the field test, cockpit procedures and pilot briefing packages for both FMS equipped and unequipped aircraft were developed in cooperation with an airline. The procedures developed for the FMS equipped aircraft were to fly a VNAV descent at a controller specified speed to cross a metering fix at a specified altitude and speed. For nonFMS aircraft, the clearance also specified a CTAS calculated top-of-descent point. Some CTAS related flight deck issues included how much time was available to the pilots' for compliance, the amount of information that needed to be interpreted in the clearance and possible repercussions of misunderstandings. Data collected during the study ranged from subjective data (including the airline pilots' opinions and comments about the new descent clearances and procedures) to objective data (including observations of aircraft performance from the flight deck). This paper will present data and the resulting changes in the design of the procedures and clearance phraseology.

  6. Entry, Descent and Landing Systems Analysis: Exploration Class Simulation Overview and Results

    NASA Technical Reports Server (NTRS)

    DwyerCianciolo, Alicia M.; Davis, Jody L.; Shidner, Jeremy D.; Powell, Richard W.

    2010-01-01

    NASA senior management commissioned the Entry, Descent and Landing Systems Analysis (EDL-SA) Study in 2008 to identify and roadmap the Entry, Descent and Landing (EDL) technology investments that the agency needed to make in order to successfully land large payloads at Mars for both robotic and exploration or human-scale missions. The year one exploration class mission activity considered technologies capable of delivering a 40-mt payload. This paper provides an overview of the exploration class mission study, including technologies considered, models developed and initial simulation results from the EDL-SA year one effort.

  7. Hybrid Steepest Descent Method for Variational Inequality Problem over the Fixed Point Set of Certain Quasi-nonexpansive Mappings

    Microsoft Academic Search

    Isao Yamada; Nobuhiko Ogura

    2005-01-01

    The hybrid steepest descent method is an algorithmic solution to the variational inequality problem over the fixed point set of nonlinear mapping and applicable to broad range of convexly constrained nonlinear inverse problems in real Hilbert space. In this paper, we show that the strong convergence theorem [Yamada, I. (2001). The hybrid steepest descent method for the variational inequality problem

  8. Cerebro-cerebellar connectivity is increased in primary lateral sclerosis

    PubMed Central

    Meoded, Avner; Morrissette, Arthur E.; Katipally, Rohan; Schanz, Olivia; Gotts, Stephen J.; Floeter, Mary Kay

    2014-01-01

    Increased functional connectivity in resting state networks was found in several studies of patients with motor neuron disorders, although diffusion tensor imaging studies consistently show loss of white matter integrity. To understand the relationship between structural connectivity and functional connectivity, we examined the structural connections between regions with altered functional connectivity in patients with primary lateral sclerosis (PLS), a long-lived motor neuron disease. Connectivity matrices were constructed from resting state fMRI in 16 PLS patients to identify areas of differing connectivity between patients and healthy controls. Probabilistic fiber tracking was used to examine structural connections between regions of differing connectivity. PLS patients had 12 regions with increased functional connectivity compared to controls, with a predominance of cerebro-cerebellar connections. Increased functional connectivity was strongest between the cerebellum and cortical motor areas and between the cerebellum and frontal and temporal cortex. Fiber tracking detected no difference in connections between regions with increased functional connectivity. We conclude that functional connectivity changes are not strongly based in structural connectivity. Increased functional connectivity may be caused by common inputs, or by reduced selectivity of cortical activation, which could result from loss of intracortical inhibition when cortical afferents are intact. PMID:25610792

  9. Endovascular Treatment for Ruptured Distal Anterior Inferior Cerebellar Artery Aneurysm

    PubMed Central

    Oh, Jae-Sang; Shim, Jai-Joon; Bae, Hack-Gun; Yoon, Il-Gyu

    2014-01-01

    A 42-year-old woman presented with Hunt and Hess grade (HHG) III subarachnoid hemorrhage (SAH) caused by a ruptured left distal anterior inferior cerebellar artery (AICA) aneurysm. Computed tomography showed a thin SAH on the cerebellopontine angle cistern, and small vermian intracerebral hemorrhage and intraventricular hemorrhage in the fourth ventricle. Digital subtraction angiography revealed the aneurysm on the postmeatal segment of left distal AICA, a branching point of rostrolateral and caudomedial branch of the left distal AICA. Despite thin caliber, tortuous running course and far distal location, the AICA aneurysm was obliterated successfully with endovascular coils without compromising AICA flow. However, the patient developed left side sensorineural hearing loss postoperatively, in spite of definite patency of distal AICA on the final angiogram. She was discharged home without neurologic sequela except hearing loss and tinnitus. Endovascular treatment of distal AICA aneurysm, beyond the meatal loop, is feasible while preserving the AICA flow. However, because the cochlear hair cell is vulnerable to ischemia, unilateral hearing loss can occur, possibly caused by the temporary occlusion of AICA flow by microcatheter during endovascular treatment. PMID:24765609

  10. False-Positive Head-Impulse Test in Cerebellar Ataxia

    PubMed Central

    Kremmyda, Olympia; Kirchner, Hanni; Glasauer, Stefan; Brandt, Thomas; Jahn, Klaus; Strupp, Michael

    2012-01-01

    The objective of this study was to compare the findings of the bedside head-impulse test (HIT), passive head rotation gain, and caloric irrigation in patients with cerebellar ataxia (CA). In 16 patients with CA and bilaterally pathological bedside HIT, vestibuloocular reflex (VOR) gains were measured during HIT and passive head rotation by scleral search coil technique. Eight of the patients had pathologically reduced caloric responsiveness, while the other eight had normal caloric responses. Those with normal calorics showed a slightly reduced HIT gain (mean?±?SD: 0.73?±?0.15). In those with pathological calorics, gains 80 and 100?ms after the HIT as well as the passive rotation VOR gains were significantly lower. The corrective saccade after head turn occurred earlier in patients with pathological calorics (111?±?62?ms after onset of the HIT) than in those with normal calorics (191?±?17?ms, p?=?0.0064). We identified two groups of patients with CA: those with an isolated moderate HIT deficit only, probably due to floccular dysfunction, and those with combined HIT, passive rotation, and caloric deficit, probably due to a peripheral vestibular deficit. From a clinical point of view, these results show that the bedside HIT alone can be false-positive for establishing a diagnosis of a bilateral peripheral vestibular deficit in patients with CA. PMID:23162531

  11. Diversity of vestibular nuclei neurons targeted by cerebellar nodulus inhibition

    PubMed Central

    Meng, Hui; Blázquez, Pablo M; Dickman, J David; Angelaki, Dora E

    2014-01-01

    Abstract?A functional role of the cerebellar nodulus and ventral uvula (lobules X and IXc,d of the vermis) for vestibular processing has been strongly suggested by direct reciprocal connections with the vestibular nuclei, as well as direct vestibular afferent inputs as mossy fibres. Here we have explored the types of neurons in the macaque vestibular nuclei targeted by nodulus/ventral uvula inhibition using orthodromic identification from the caudal vermis. We found that all nodulus-target neurons are tuned to vestibular stimuli, and most are insensitive to eye movements. Such non-eye-movement neurons are thought to project to vestibulo-spinal and/or thalamo-cortical pathways. Less than 20% of nodulus-target neurons were sensitive to eye movements, suggesting that the caudal vermis can also directly influence vestibulo-ocular pathways. In general, response properties of nodulus-target neurons were diverse, spanning the whole continuum previously described in the vestibular nuclei. Most nodulus-target cells responded to both rotation and translation stimuli and only a few were selectively tuned to translation motion only. Other neurons were sensitive to net linear acceleration, similar to otolith afferents. These results demonstrate that, unlike the flocculus and ventral paraflocculus which target a particular cell group, nodulus/ventral uvula inhibition targets a large diversity of cell types in the vestibular nuclei, consistent with a broad functional significance contributing to vestibulo-ocular, vestibulo-thalamic and vestibulo-spinal pathways. PMID:24127616

  12. Impaired cerebellar functions in mutant mice lacking DNER.

    PubMed

    Tohgo, Akira; Eiraku, Mototsugu; Miyazaki, Taisuke; Miura, Eriko; Kawaguchi, Shin-Ya; Nishi, Miyuki; Watanabe, Masahiko; Hirano, Tomoo; Kengaku, Mineko; Takeshima, Hiroshi

    2006-02-01

    DNER is a transmembrane protein carrying extracellular EGF repeats and is strongly expressed in Purkinje cells (PCs) in the cerebellum. Current study indicated that DNER functions as a new Notch ligand and mediates the functional communication via cell-cell interaction. By producing and analyzing knockout mice lacking DNER, we demonstrate its essential roles in functional and morphological maturation of the cerebellum. The knockout mice exhibited motor discoordination in the fixed bar and rota-rod tests. The cerebellum from the knockout mice showed significant retardation in morphogenesis and persistent abnormality in fissure organization. Histochemical and electrophysiological analyses detected that PCs retained multiple innervations from climbing fibers (CFs) in the mutant cerebellum. Synaptic transmission from parallel fibers (PFs) or CFs to PCs was apparently normal, while glutamate clearance at the PF-PC synapses was significantly impaired in the mutant mice. Moreover, the protein level of GLAST, the glutamate transporter predominantly expressed in Bergmann glia (BG), was reduced in the mutant cerebellum. Our results indicate that DNER takes part in stimulation of BG maturation via intercellular communication and is essential for precise cerebellar development. PMID:16298139

  13. Genetic effects on the cerebellar role in working memory: Same brain, different genes?

    PubMed Central

    Blokland, Gabriëlla A.M.; McMahon, Katie L.; Thompson, Paul M.; Hickie, Ian B.; Martin, Nicholas G.; de Zubicaray, Greig I.; Wright, Margaret J.

    2013-01-01

    Over the past several years, evidence has accumulated showing that the cerebellum plays a significant role in cognitive function. Here we show, in a large genetically informative twin sample (n = 430; aged 16–30 years), that the cerebellum is strongly, and reliably (n = 30 rescans), activated during an n-back working memory task, particularly lobules I–IV, VIIa Crus I and II, IX and the vermis. Monozygotic twin correlations for cerebellar activation were generally much larger than dizygotic twin correlations, consistent with genetic influences. Structural equation models showed that up to 65% of the variance in cerebellar activation during working memory is genetic (averaging 34% across significant voxels), most prominently in the lobules VI, and VIIa Crus I, with the remaining variance explained by unique/unshared environmental factors. Heritability estimates for brain activation in the cerebellum agree with those found for working memory activation in the cerebral cortex, even though cerebellar cyto-architecture differs substantially. Phenotypic correlations between BOLD percent signal change in cerebrum and cerebellum were low, and bivariate modeling indicated that genetic influences on the cerebellum are at least partly specific to the cerebellum. Activation on the voxel-level correlated very weakly with cerebellar gray matter volume, suggesting specific genetic influences on the BOLD signal. Heritable signals identified here should facilitate discovery of genetic polymorphisms influencing cerebellar function through genome-wide association studies, to elucidate the genetic liability to brain disorders affecting the cerebellum. PMID:24128737

  14. Cerebellar Direct Current Stimulation Enhances On-Line Motor Skill Acquisition through an Effect on Accuracy.

    PubMed

    Cantarero, Gabriela; Spampinato, Danny; Reis, Janine; Ajagbe, Loni; Thompson, Tziporah; Kulkarni, Kopal; Celnik, Pablo

    2015-02-18

    The cerebellum is involved in the update of motor commands during error-dependent learning. Transcranial direct current stimulation (tDCS), a form of noninvasive brain stimulation, has been shown to increase cerebellar excitability and improve learning in motor adaptation tasks. Although cerebellar involvement has been clearly demonstrated in adaptation paradigms, a type of task that heavily relies on error-dependent motor learning mechanisms, its role during motor skill learning, a behavior that likely involves error-dependent as well as reinforcement and strategic mechanisms, is not completely understood. Here, in humans, we delivered cerebellar tDCS to modulate its activity during novel motor skill training over the course of 3 d and assessed gains during training (on-line effects), between days (off-line effects), and overall improvement. We found that excitatory anodal tDCS applied over the cerebellum increased skill learning relative to sham and cathodal tDCS specifically by increasing on-line rather than off-line learning. Moreover, the larger skill improvement in the anodal group was predominantly mediated by reductions in error rate rather than changes in movement time. These results have important implications for using cerebellar tDCS as an intervention to speed up motor skill acquisition and to improve motor skill accuracy, as well as to further our understanding of cerebellar function. PMID:25698763

  15. A magnetic resonance imaging study of cerebellar volume in tuberous sclerosis complex.

    PubMed

    Weisenfeld, Neil I; Peters, Jurriaan M; Tsai, Peter T; Prabhu, Sanjay P; Dies, Kira A; Sahin, Mustafa; Warfield, Simon K

    2013-02-01

    The cerebellum plays an important role in motor learning and cognition, and structural cerebellar abnormalities have been associated with cognitive impairment. In tuberous sclerosis complex, neurologic outcome is highly variable, and no consistent imaging or pathologic determinant of cognition has been firmly established. The cerebellum calls for specific attention because mouse models of tuberous sclerosis complex have demonstrated a loss of cerebellar Purkinje cells, and cases of human histologic data have demonstrated a similar loss in patients. We hypothesized that there might be a common cerebellar finding in tuberous sclerosis complex that could be measured as morphometric changes with magnetic resonance imaging. Using a robust, automated image analysis procedure, we studied 36 patients with tuberous sclerosis complex and age-matched control subjects and observed significant volume loss among patients in the cerebellar cortices and vermis. Furthermore, this effect was strongest in a subgroup of 19 patients with a known, pathogenic mutation of the tuberous sclerosis 2 gene and impacted all cerebellar structures. We conclude that patients with tuberous sclerosis complex exhibit volume loss in the cerebellum, and this loss is larger and more widespread in patients with a tuberous sclerosis 2 mutation. PMID:23337002

  16. Integration of Purkinje cell inhibition by cerebellar nucleo-olivary neurons.

    PubMed

    Najac, Marion; Raman, Indira M

    2015-01-14

    Neurons in the cerebellar cortex, cerebellar nuclei, and inferior olive (IO) form a trisynaptic loop critical for motor learning. IO neurons excite Purkinje cells via climbing fibers and depress their parallel fiber inputs. Purkinje cells inhibit diverse cells in the cerebellar nuclei, including small GABAergic nucleo-olivary neurons that project to the IO. To investigate how these neurons integrate synaptic signals from Purkinje cells, we retrogradely labeled nucleo-olivary cells in the contralateral interpositus and lateral nuclei with cholera toxin subunit B-Alexa Fluor 488 and recorded their electrophysiological properties in cerebellar slices from weanling mice. Nucleo-olivary cells fired action potentials over a relatively narrow dynamic range (maximal rate, ? 70 spikes/s), unlike large cells that project to premotor areas (maximal rate, ? 400 spikes/s). GABA(A) receptor-mediated IPSCs evoked by electrical or optogenetic stimulation of Purkinje cells were more than 10-fold slower in nucleo-olivary cells (decay time, ? 25 ms) than in large cells (? 2 ms), and repetitive stimulation at 20-150 Hz evoked greatly summating IPSCs. Nucleo-olivary firing rates varied inversely with IPSP frequency, and the timing of Purkinje IPSPs and nucleo-olivary spikes was uncorrelated. These attributes contrast with large cells, whose brief IPSCs and rapid firing rates can permit well timed postinhibitory spiking. Thus, the intrinsic and synaptic properties of these two projection neurons from the cerebellar nuclei tailor them for differential integration and transmission of their Purkinje cell input. PMID:25589749

  17. A test of the cerebellar hypothesis of dyslexia in adequate and inadequate responders to reading intervention

    PubMed Central

    Barth, Amy E.; Denton, Carolyn A.; Stuebing, Karla K.; Fletcher, Jack M.; Cirino, Paul T.; Francis, David J.; Vaughn, Sharon

    2013-01-01

    The cerebellar hypothesis of dyslexia posits that cerebellar deficits are associated with reading disabilities and may explain why some individuals with reading disabilities fail to respond to reading interventions. We tested these hypotheses in a sample of children who participated in a grade 1 reading intervention study (n = 174) and a group of typically achieving children (n = 62). At posttest, children were classified as adequately responding to the intervention (n = 82), inadequately responding with decoding and fluency deficits (n = 36), or inadequately responding with only fluency deficits (n = 56). Based on the Bead Threading and Postural Stability subtests from the Dyslexia Screening Test-Junior, we found little evidence that assessments of cerebellar functions were associated with academic performance or responder status. In addition, we did not find evidence supporting the hypothesis that cerebellar deficits are more prominent for poor readers with “specific” reading disabilities (i.e., with discrepancies relative to IQ) than for poor readers with reading scores consistent with IQ. In contrast, measures of phonological awareness, rapid naming, and vocabulary were strongly associated with responder status and academic outcomes. These results add to accumulating evidence that fails to associate cerebellar functions with reading difficulties. PMID:20298639

  18. Regional cerebellar volumes are related to early musical training and finger tapping performance.

    PubMed

    Baer, L H; Park, M T M; Bailey, J A; Chakravarty, M M; Li, K Z H; Penhune, V B

    2015-04-01

    The cerebellum has been associated with timing on the millisecond scale and with musical rhythm and beat processing. Early musical training (before age 7) is associated with enhanced rhythm synchronization performance and differences in cortical motor areas and the corpus callosum. In the present study, we examined the relationships between regional cerebellar volumes, early musical training, and timing performance. We tested adult musicians and non-musicians on a standard finger tapping task, and extracted cerebellar gray and white matter volumes using a novel multi-atlas automatic segmentation pipeline. We found that early-trained musicians had reduced volume in bilateral cerebellar white matter and right lobules IV, V and VI, compared to late-trained musicians. Strikingly, better timing performance, greater musical experience and an earlier age of start of musical training were associated with smaller cerebellar volumes. Better timing performance was specifically associated with smaller volumes of right lobule VI. Collectively, these findings support the sensitivity of the cerebellum to the age of initiation of musical training and suggest that lobule VI plays a role in timing. The smaller cerebellar volumes associated with musical training and timing performance may be a reflection of more efficiently implemented low-level timing and sensorimotor processes. PMID:25583606

  19. Autopsy case of acute encephalopathy linked to familial hemiplegic migraine with cerebellar atrophy and mental retardation.

    PubMed

    Takahashi, Tatsuya; Arai, Nobutaka; Shimamura, Megumi; Suzuki, Yume; Yamashita, Sumimasa; Iwamoto, Hiroko; Inayama, Yoshiaki; Kameda, Youichi; Kuroiwa, Yoshiyuki

    2005-09-01

    A 19-year-old female patient, who had exhibited esotropia, mild cerebellar ataxia, mild mental retardation, and cerebellar atrophy on magnetic resonance images at the age of 15, developed signs of acute encephalopathy, and thereafter died of disseminated intravascular coagulation on the day of her admission. Both her mother and sister suffered from attacks of hemiplegic migraine, mild mental retardation, and cerebellar ataxia. Neuropathological examinations revealed acute changes in the widespread cerebral cortex, chronic degenerative changes in the anterior lobe of the cerebellar vermis, axonal spheroids in the Goll's nucleus, pseudo-calcinosis in the globus pallidus, and glial bundles in the cranial nerves. The most fascinating features were changes of Purkinje cells, such as cactuses (asteroid bodies, dendritic expansions), somatic sprouts, and torpedoes. These changes may be characteristic of familial hemiplegic migraine with cerebellar atrophy, as well as the other metabolic diseases, such as Menkes' kinky hair disease, infantile (Tay-Sachs type) amaurotic idiocy, organic mercury intoxication, and mitochondrial encephalopathy, of which cases often exhibit such pathological changes of Purkinje cells. Therefore, familial hemiplegic migraine may share some metabolic abnormalities with the diseases mentioned above. PMID:16193840

  20. Cerebellar motor learning: are environment dynamics more important than error size?

    PubMed Central

    Gibo, Tricia L.; Criscimagna-Hemminger, Sarah E.; Okamura, Allison M.

    2013-01-01

    Cerebellar damage impairs the control of complex dynamics during reaching movements. It also impairs learning of predictable dynamic perturbations through an error-based process. Prior work suggests that there are distinct neural mechanisms involved in error-based learning that depend on the size of error experienced. This is based, in part, on the observation that people with cerebellar degeneration may have an intact ability to learn from small errors. Here we studied the relative effect of specific dynamic perturbations and error size on motor learning of a reaching movement in patients with cerebellar damage. We also studied generalization of learning within different coordinate systems (hand vs. joint space). Contrary to our expectation, we found that error size did not alter cerebellar patients' ability to learn the force field. Instead, the direction of the force field affected patients' ability to learn, regardless of whether the force perturbations were introduced gradually (small error) or abruptly (large error). Patients performed best in fields that helped them compensate for movement dynamics associated with reaching. However, they showed much more limited generalization patterns than control subjects, indicating that patients rely on a different learning mechanism. We suggest that patients typically use a compensatory strategy to counteract movement dynamics. They may learn to relax this compensatory strategy when the external perturbation is favorable to counteracting their movement dynamics, and improve reaching performance. Altogether, these findings show that dynamics affect learning in cerebellar patients more than error size. PMID:23596337

  1. Effects of Human Cerebellar Thalamus Disruption on Adaptive Control of Reaching

    PubMed Central

    Chen, Haiyin; Hua, Sherwin E.; Smith, Maurice A.; Lenz, Frederick A.; Shadmehr, Reza

    2006-01-01

    Lesion or degeneration of the cerebellum can profoundly impair adaptive control of reaching in humans. Computational models have proposed that internal models that help control movements form in the cerebellum and influence planned motor output through the cerebello-thalamo-cortical pathway. However, lesion studies of the cerebellar thalamus have not consistently found impairment in reaching or adaptation of reaching. To elucidate the role of the cerebellar thalamus in humans, we studied a group of essential tremor (ET) patients with deep brain stimulation (DBS) electrodes placed in the cerebellar thalamus. The stimulation can be turned on or off remotely and is thought to reduce tremor by blocking the spread of the pathological output from the cerebellum. We studied the effect of thalamic DBS on the ability to adapt arm movements to novel force fields. Although thalamic DBS resulted in a dramatic and significant reduction of tremor in ET, it also impaired motor adaptation: the larger the stimulation voltage, the greater the reduction in rates of adaptation. We next examined ET patients that had undergone unilateral thalamotomy in the cerebellar thalamus and found that adaptation with the contralateral arm was impaired compared with the ipsilateral arm. Therefore, although both lesion and electrical stimulation of the cerebellar thalamus are highly effective in reducing tremor, they significantly impair the ability of the brain to form internal models of action. Adaptive control of reaching appears to depend on the integrity of the cerebello-thalamo-cortical pathway. PMID:16357337

  2. Anti-Ca/anti-ARHGAP26 antibodies associated with cerebellar atrophy and cognitive decline.

    PubMed

    Doss, Sarah; Nümann, Astrid; Ziegler, Annerose; Siebert, Eberhard; Borowski, Kathrin; Stöcker, Winfried; Prüss, Harald; Wildemann, Brigitte; Endres, Matthias; Jarius, Sven

    2014-02-15

    Recently, we identified a novel Purkinje cell-specific autoantibody (termed anti-Ca) targeting rhoGTPase-activating-protein-26 (ARHGAP26) in a patient with cerebellar ataxia. Here we describe a new case of anti-Ca/ARHGAP26 antibody-positive cerebellar ataxia. Cerebellar ataxia was associated with signs of possible limbic encephalitis in this case. The 24-year-old man presented with subacute pancerebellar ataxia, flattened affect, and cognitive decline. Neuropsychological testing revealed working memory deficits, compromised verbal learning and recall, attention deficits, slowed information processing, interference difficulty, and reduced spatial recognition. MRI showed severe pancerebellar atrophy. Serological examinations revealed high-titre anti-Ca/anti-ARHGAP26 antibodies. The antibodies belonged to the IgG1 subclass and were produced intrathecally. This case further corroborates the association of anti-Ca antibodies with cerebellar ataxia, expands the clinical spectrum, and highlights the necessity of antigen-specific diagnostic testing in immune-mediated cerebellar ataxia. PMID:24439423

  3. Cerebellar vermal volumes and behavioral correlates in children with autism spectrum disorder

    PubMed Central

    Webb, Sara Jane; Sparks, Bobbi-Faun; Friedman, Seth D.; Shaw, Dennis W. W.; Giedd, Jay; Dawson, Geraldine; Dager, Steven R.

    2009-01-01

    Cerebellar histopathological abnormalities have been well documented in autism although findings of structural differences, as determined by magnetic resonance imaging, have been less consistent. This report explores specific cerebellar vermal structures and their relation with symptoms severity and cognitive functioning in young children with autism spectrum disorder (ASD). Children with ASD aged 3 to 4 years were compared with chronological age matched typically developing children (TD) and chronologic and mental age matched children with developmental delay (DD). Volumes of the cerebellum and midsagittal vermal areas were measured from 3-D T1-weighted MR images. Children with ASD had reduced total vermis volumes compared to children with TD after controlling for age, sex, and overall cerebral volume or cerebellum volume. In particular, the vermis lobe VI-VII area was reduced in children with ASD compared to TD children. Children with DD had smaller total vermis areas compared to children with ASD and TD. Within the ASD group, cerebellar measurements were not correlated with symptom severity, or verbal, non-verbal or full scale IQ. Within the DD group, larger cerebellar measurements were correlated with less impairments. The specific relation between altered cerebellar structure and symptom expression in autism remains unclear. PMID:19243924

  4. Dynamic modulation of cerebellar excitability for abrupt, but not gradual visuomotor adaptation

    PubMed Central

    Schlerf, John E; Galea, Joseph M; Bastian, Amy J; Celnik, Pablo A

    2012-01-01

    The cerebellum is critically important for error driven adaptive motor learning, as evidenced by the fact that cerebellar patients do not adapt well to sudden predictable perturbations. However, recent work has shown that cerebellar patients adapt much better if the perturbation is gradually introduced. Here we explore physiological mechanisms that underlie this distinction between abrupt and gradual motor adaptation in humans. We used Transcranial Magnetic Stimulation (TMS) to evaluate whether neural mechanisms within the cerebellum contribute to either process during a visuomotor reach adaptation. When a visuomotor rotation was introduced abruptly, cerebellar excitability changed early in learning, and approached baseline levels near the end of the adaptation block. However, we observed no modulation of cerebellar excitability when we presented the visuomotor rotation gradually during learning. Similarly, we did not observe cerebellar modulation during trial-by-trial adaptation to random visuomotor displacements or during reaches without perturbations. This suggests that the cerebellum is most active during the early-phases of adaptation when large perturbations are successfully compensated. PMID:22915105

  5. Humor, laughter, and the cerebellum: insights from patients with acute cerebellar stroke.

    PubMed

    Frank, B; Andrzejewski, K; Göricke, S; Wondzinski, E; Siebler, M; Wild, B; Timmann, D

    2013-12-01

    Extent of cerebellar involvement in cognition and emotion is still a topic of ongoing research. In particular, the cerebellar role in humor processing and control of laughter is not well known. A hypermetric dysregulation of affective behavior has been assumed in cerebellar damage. Thus, we aimed at investigating humor comprehension and appreciation as well as the expression of laughter in 21 patients in the acute or subacute state after stroke restricted to the cerebellum, and in the same number of matched healthy control subjects. Patients with acute and subacute cerebellar damage showed preserved comprehension and appreciation of humor using a validated humor test evaluating comprehension, funniness and aversiveness of cartoons ("3WD Humor Test"). Additionally, there was no difference when compared to healthy controls in the number and intensity of facial reactions and laughter while observing jokes, humorous cartoons, or video sketches measured by the Facial Action Coding System. However, as depression scores were significantly increased in patients with cerebellar stroke, a concealing effect of accompanying depression cannot be excluded. Current findings add to descriptions in the literature that cognitive or affective disorders in patients with lesions restricted to the cerebellum, even in the acute state after damage, are frequently mild and might only be present in more sensitive or specific tests. PMID:23661243

  6. Cerebellar cortical neuron responses evoked from the spinal border cell tract

    PubMed Central

    Geborek, Pontus; Spanne, Anton; Bengtsson, Fredrik; Jörntell, Henrik

    2013-01-01

    Spinocerebellar systems are likely to be crucial for cerebellar hallmark functions such as coordination. However, in terms of cerebellar functional analyses, these are perhaps among the least explored systems. The aim of the present study is to achieve activation of a single component of the spinocerebellar systems and to explore to what extent it can influence the spike output of granule cells, Golgi cells, molecular layer (ML) interneurons (stellate and basket cells) and Purkinje cells (PCs). For this purpose, we took advantage of a unique arrangement discovered in neuroanatomical studies, in which the spinal border cell (SBC) component of the ventral spinocerebellar system was found to be the only spinocerebellar tract which ascends in the contralateral lateral funiculus (coLF) and have terminations in sublobulus C1 of the paramedian lobule in the posterior cerebellum. Using electrical stimulation of this tract, we find a subset of the cerebellar cortical neurons in this region to be moderately or powerfully activated. For example, some of our granule cells displayed high intensity responses whereas the majority of the granule cells displayed no response at all. The finding that more than half of the PCs were activated by stimulation of the SBC tract indicated that this system is capable of directly influencing cerebellar cortical output. The implications of these findings for the view of the integrative functions of the cerebellar cortex are discussed. PMID:24115921

  7. Journal of Machine Learning Research 10 (2009) 17371754 Submitted 1/09; Revised 4/09; Published 7/09 SGDQN: Careful QuasiNewton Stochastic Gradient Descent

    E-print Network

    Bottou, Léon

    2009-01-01

    /09 SGD­QN: Careful Quasi­Newton Stochastic Gradient Descent Antoine Bordes # ANTOINE.BORDES@LIP6.FR LIP6 is a stochastic gradient descent algorithm that makes careful use of second­ order information and splits as fast as a first­order stochastic gradient descent but requires less iterations to achieve the same

  8. Sexual Health Discussions between African-American Mothers and Mothers of Latino Descent and Their Children

    ERIC Educational Resources Information Center

    Murray, Ashley; Ellis, Monica U.; Castellanos, Ted; Gaul, Zaneta; Sutton, Madeline Y.; Sneed, Carl D.

    2014-01-01

    We examined approaches used by African-American mothers and mothers of Latino descent for informal sex-related discussions with their children to inform sexually transmitted infection (STI)/HIV intervention development efforts. We recruited mothers (of children aged 12-15) from youth service agencies and a university in southern California.…

  9. Coordinate Descent Methods @ SIAM Conference on Optimization, San Diego, May 2014

    E-print Network

    Edinburgh, University of

    Coordinate Descent Methods @ SIAM Conference on Optimization, San Diego, May 2014 Organizers: Peter Peter Richtarik and Olivier Fercoq, University of Edinburgh, United Kingdom 11:15-11:40 Stochastic Dual Fercoq and Peter Richtarik, University of Edinburgh, United Kingdom 3:30-3:55 Stochastic Block Mirror

  10. Access to Health Care Among Latinos of Mexican Descent in "Colonias" in Two Texas Counties

    ERIC Educational Resources Information Center

    Ortiz, Larry; Arizmendi, Lydia; Cornelius, Llewellyn J.

    2004-01-01

    Critical to resolving the problem of health disparities among Latinos is examining the needs within ethnic subpopulations. This paper focused on the unique challenges encountered by one ethnic subpopulation -- Latinos of Mexican descent living in colonias. Findings reaffirm the importance of looking within ethnic subpopulations to understand the…

  11. A molecular signature of an arrest of descent in human parturition

    PubMed Central

    MITTAL, Pooja; ROMERO, Roberto; TARCA, Adi L.; DRAGHICI, Sorin; NHAN-CHANG, Chia-Ling; CHAIWORAPONGSA, Tinnakorn; HOTRA, John; GOMEZ, Ricardo; KUSANOVIC, Juan Pedro; LEE, Deug-Chan; KIM, Chong Jai; HASSAN, Sonia S.

    2010-01-01

    Objective This study was undertaken to identify the molecular basis of an arrest of descent. Study Design Human myometrium was obtained from women in term labor (TL; n=29) and arrest of descent (AODes, n=21). Gene expression was characterized using Illumina® HumanHT-12 microarrays. A moderated t-test and false discovery rate adjustment were applied for analysis. Confirmatory qRT-PCR and immunoblot was performed in an independent sample set. Results 400 genes were differentially expressed between women with an AODes compared to those with TL. Gene Ontology analysis indicated enrichment of biological processes and molecular functions related to inflammation and muscle function. Impacted pathways included inflammation and the actin cytoskeleton. Overexpression of HIF1A, IL-6, and PTGS2 in AODES was confirmed. Conclusion We have identified a stereotypic pattern of gene expression in the myometrium of women with an arrest of descent. This represents the first study examining the molecular basis of an arrest of descent using a genome-wide approach. PMID:21284969

  12. Multipoint Approximations of Identity-by-Descent Probabilities for Accurate Linkage Analysis of Distantly Related Individuals

    Microsoft Academic Search

    Cornelis A. Albers; Jim Stankovich; Russell Thomson; Melanie Bahlo; Hilbert J. Kappen

    2008-01-01

    We propose an analytical approximation method for the estimation of multipoint identity by descent (IBD) probabilities in pedigrees containing a moderate number of distantly related individuals. We show that in large pedigrees where cases are related through untyped ancestors only, it is possible to formulate the hidden Markov model of the Lander-Green algorithm in terms of the IBD configurations of

  13. Constrained Stochastic Gradient Descent for Large-scale Least Squares Problem

    E-print Network

    Ding, Wei

    risk. For large-scale problems, the classical optimization meth- ods, such as interior point method] methods show its promising efficiency in solving large-scale problems. Some of them have been widely to solve the large- scale least squares problem. CSGD improves the Stochastic Gradient Descent (SGD

  14. ADAPTATION IN WEIGHT SPACE THROUGH GRADIENT DESCENT FOR HOPFIELD NET AS STATIC OPTIMIZER: IS IT FEASIBLE?

    E-print Network

    Serpen, Gursel

    through gradient descent for a Hopfield neural network configured as a static optimizer and tested of an adaptation scheme in the weight space of Hopfield neural networks configured for static optimization AND ADAPTATION A Hopfield neural network is a nonlinear dynamical system [Hopfield, 1985] with the following

  15. Smart-Divert Powered Descent Guidance to Avoid the Backshell Landing Dispersion Ellipse

    NASA Technical Reports Server (NTRS)

    Carson, John M.; Acikmese, Behcet

    2013-01-01

    A smart-divert capability has been added into the Powered Descent Guidance (PDG) software originally developed for Mars pinpoint and precision landing. The smart-divert algorithm accounts for the landing dispersions of the entry backshell, which separates from the lander vehicle at the end of the parachute descent phase and prior to powered descent. The smart-divert PDG algorithm utilizes the onboard fuel and vehicle thrust vectoring to mitigate landing error in an intelligent way: ensuring that the lander touches down with minimum- fuel usage at the minimum distance from the desired landing location that also avoids impact by the descending backshell. The smart-divert PDG software implements a computationally efficient, convex formulation of the powered-descent guidance problem to provide pinpoint or precision-landing guidance solutions that are fuel-optimal and satisfy physical thrust bound and pointing constraints, as well as position and speed constraints. The initial smart-divert implementation enforced a lateral-divert corridor parallel to the ground velocity vector; this was based on guidance requirements for MSL (Mars Science Laboratory) landings. This initial method was overly conservative since the divert corridor was infinite in the down-range direction despite the backshell landing inside a calculable dispersion ellipse. Basing the divert constraint instead on a local tangent to the backshell dispersion ellipse in the direction of the desired landing site provides a far less conservative constraint. The resulting enhanced smart-divert PDG algorithm avoids impact with the descending backshell and has reduced conservatism.

  16. Optimizing 0/1 Loss for Perceptrons by Random Coordinate Descent

    E-print Network

    Abu-Mostafa, Yaser S.

    Optimizing 0/1 Loss for Perceptrons by Random Coordinate Descent Ling Li and Hsuan-Tien Lin Abstract--The 0/1 loss is an important cost function for perceptrons. Nevertheless it cannot be easily minimized by most existing perceptron learning algorithms. In this paper, we propose a family of random

  17. Synthesis of Attitude Control for a Gyroscopic Stabilizer of the Navigation System of a Descent Vehicle

    NASA Astrophysics Data System (ADS)

    Sokolov, S. V.; Pogorelov, V. A.

    2001-09-01

    The possibility to synthesize the attitude control for a gyrostabilized platform is investigated under the most general assumptions on its drifts, using the principle of maximum. The analytical form of the control vector, explicitly depending on all components of the state vector of a navigation system of a descent vehicle, is a specific feature of the found solution.

  18. PARTIAL DESCENT ON HYPERELLIPTIC CURVES AND THE GENERALIZED FERMAT EQUATION x3

    E-print Network

    Stoll, Michael

    PARTIAL DESCENT ON HYPERELLIPTIC CURVES AND THE GENERALIZED FERMAT EQUATION x3 + y4 + z5 = 0 SAMIR then C(Q) = . We shall demonstrate the effectiveness of our new method by solving the generalized Fermat new method by solving the generalized Fermat equation with signature (3, 4, 5). Let p, q, r Z2

  19. The Role of Educational Background, Activity, and Past Experiences in Mexican-Descent Families' Science Conversations.

    ERIC Educational Resources Information Center

    Tenenbaum, Harriet R.; Callanan, Maureen A.; Alba-Speyer, Consuelo; Sandoval, Leticia

    2002-01-01

    Two studies investigated science conversations between Mexican-descent parents and children during a visit to a children's museum and at home after a family science workshop. Although more-educated parents gave more explanations about science in the museum, all families engaged in causal conversations, especially at home. (Contains 42 references.)…

  20. A concept for the entry, descent, and landing of high-mass payloads at Mars

    Microsoft Academic Search

    Ashley M. Korzun; Gregory F. Dubos; Curtis K. Iwata; Benjamin A. Stahl; John J. Quicksall

    2010-01-01

    The architecture concepts and aggressive science objectives for the next phases of Mars exploration will require landed masses an order of magnitude or greater than any Mars mission previously planned or flown. Additional studies have shown the requirements for missions more ambitious than the 2009 Mars Science Laboratory (?900kg payload mass) to extend beyond the capabilities of Viking-heritage entry, descent,

  1. High-Resolution Detection of Identity by Descent in Unrelated Individuals

    PubMed Central

    Browning, Sharon R.; Browning, Brian L.

    2010-01-01

    Detection of recent identity by descent (IBD) in population samples is important for population-based linkage mapping and for highly accurate genotype imputation and haplotype-phase inference. We present a method for detection of recent IBD in population samples. Our method accounts for linkage disequilibrium between SNPs to enable full use of high-density SNP data. We find that our method can detect segments of a length of 2 cM with moderate power and negligible false discovery rate in Illumina 550K data in Northwestern Europeans. We compare our method with GERMLINE and PLINK, and we show that our method has a level of resolution that is significantly better than these existing methods, thus extending the usefulness of recent IBD in analysis of high-density SNP data. We survey four genomic regions in a sample of UK individuals of European descent and find that on average, at a given location, our method detects IBD in 2.7 per 10,000 pairs of individuals in Illumina 550K data. We also present methodology and results for detection of homozygosity by descent (HBD) and survey the whole genome in a sample of 1373 UK individuals of European descent. We detect HBD in 4.7 individuals per 10,000 on average at a given location. Our methodology is implemented in the freely available BEAGLE software package. PMID:20303063

  2. Forward stair descent with hybrid neuroprosthesis after paralysis: Single case study demonstrating feasibility.

    PubMed

    Bulea, Thomas C; Kobetic, Rudi; Audu, Musa L; Schnellenberger, John R; Pinault, Gilles; Triolo, Ronald J

    2014-01-01

    The ability to negotiate stairs is important for community access and independent mobility but requires more effort and strength than level walking. For this reason, previous attempts to utilize functional neuromuscular stimulation (FNS) to restore stair navigation after spinal cord injury (SCI) have had limited success and are not readily generalizable. Stair descent is particularly challenging because it requires energy absorption via eccentric muscle contractions, a task not easily accomplished with FNS. This article presents the design and initial testing of a hybrid neuroprosthesis with a variable impedance knee mechanism (VIKM-HNP) for stair descent. Using a 16-channel percutaneous FNS system, a muscle activation pattern was synthesized to descend stairs with the VIKM-HNP in a step-by-step fashion. A finite state control system was implemented to deactivate knee extensor stimulation and utilize the VIKM-HNP to absorb energy and regulate descent speed. Feasibility testing was performed on one individual with complete thoracic-level SCI. Stair descent was achieved with maximum upper-limb forces of less than 45% body weight compared with previously reported value of 70% with FNS only. The experiments also provided insight into design requirements for future hybrid systems for stair navigation, the implications of which are discussed. PMID:25437932

  3. BLOCK TRANSFORM ADAPTATION BY STOCHASTIC GRADIENT DESCENT Vivek K Goyal and Martin Vetterli

    E-print Network

    Goyal, Vivek K

    BLOCK TRANSFORM ADAPTATION BY STOCHASTIC GRADIENT DESCENT Vivek K Goyal and Martin Vetterli transform coding it is of- ten desirable for the transform to approximate a local Karhunen- Lo`eve Transform for the source. Determining such a transform is equivalent to finding the eigenvectors of the correlation matrix

  4. Conjugate gradient methods with sufficient descent condition for large-scale unconstrained optimization

    NASA Astrophysics Data System (ADS)

    Ling, Mei Mei; Leong, Wah June

    2014-12-01

    In this paper, we make a modification to the standard conjugate gradient method so that its search direction satisfies the sufficient descent condition. We prove that the modified conjugate gradient method is globally convergent under Armijo line search. Numerical results show that the proposed conjugate gradient method is efficient compared to some of its standard counterparts for large-scale unconstrained optimization.

  5. Localization of Mars rovers using descent and surface-based image data

    E-print Network

    Olson, Clark F.

    Localization of Mars rovers using descent and surface-based image data Rongxing Li, Fei Ma 20 September 2001; published 30 August 2002. [1] The planned 2003 Mars Exploration Rover (MER Planetology: Solar System Objects: Mars; KEYWORDS: Mars rover, localization, mapping, topography, bundle

  6. TITAN WIND EFFECTS ON THE DESCENT TRAJECTORY OF THE ESA HUYGENS PROBE B. Kazeminejad1

    E-print Network

    Atkinson, David H.

    1 TITAN WIND EFFECTS ON THE DESCENT TRAJECTORY OF THE ESA HUYGENS PROBE B. Kazeminejad1 , J/Huygens mission to Saturn and Titan. The Cassini/Huygens spacecraft was launched on 15 October 1997 and enter the atmosphere of Titan on 14 January 2005. A recently discovered design flaw in the Huygens radio

  7. Cardiac Structure and Exercise Blood Pressure in Urban and Rural Canadian Men of Icelandic Descent

    Microsoft Academic Search

    Barbara J. Naimark; Arnold Naimark; Robert B. Tate; Stefan B. Sigurdsson; Johann Axelsson

    1996-01-01

    The objective of the study was to determine the relationship between exercise systolic blood pressure (ESBP), during bicycle ergometry, and echocardiographically determined left ventricular structure in rural and urban Canadian men of Icelandic descent. The study was cross-sectional in design. The settings were urban Winnipeg and the rural Interlake District in the province of Manitoba, Canada. Subjects were adult male

  8. Heritage Learners of Mexican Descent in Higher Education: A Qualitative Study of Past and Present Experiences

    ERIC Educational Resources Information Center

    Gignoux, Alicia

    2009-01-01

    This is a qualitative interpretive study that explores the past and present experiences of heritage learners (HLs) of Mexican descent who were studying or had recently studied advanced Spanish in institutions of higher education. All of the participants had been exposed to Spanish in the home and began their studies in elementary or middle school…

  9. Space shuttle descent flight control design requirements and experiments Learned, Pt. 1 p 617-628

    NASA Technical Reports Server (NTRS)

    Kafer, G.; Wilson, D.

    1983-01-01

    Some of the lessons learned during the development of the Space Shuttle descent flight control system (FCS) are reviewed. Examples confirm the importance for requirements definition, systems level analyses, and testing. In sounding these experiences may have implication for future designs or suggest the discipline required in this engineering art.

  10. A comparison of inexact newton and coordinate descent mesh optimization techniques.

    SciTech Connect

    Munson, Todd (Argonne National Laboratory, Argonne, IL); Diachin, Lori Freitag (Lawrence Livermore National Laboratory, Livermore, CA); Knupp, Patrick Michael; Shontz, Suzanne M. (Cornell University, Ithaca, NY)

    2004-07-01

    We compare inexact Newton and coordinate descent methods for optimizing the quality of a mesh by repositioning the vertices, where quality is measured by the harmonic mean of the mean-ratio metric. The effects of problem size, element size heterogeneity, and various vertex displacement schemes on the performance of these algorithms are assessed for a series of tetrahedral meshes.

  11. Space-Based Nonlinear Dynamic Inversion Control for Aircraft Continuous Descent Approach

    E-print Network

    Paris-Sud XI, Université de

    and safety in flight operations. This communi- cation proposes a new representation of aircraft flightSpace-Based Nonlinear Dynamic Inversion Control for Aircraft Continuous Descent Approach Hakim aircraft. The main novelty is that the adopted independent variable is the distance to land. This new

  12. A dual coordinate descent method for large-scale linear SVM

    Microsoft Academic Search

    Cho-jui Hsieh; Kai-wei Chang; Chih-jen Lin; S. Sathiya Keerthi; S. Sundararajan

    2008-01-01

    In many applications, data appear with a huge number of instances as well as features. Linear Support Vector Machines (SVM) is one of the most popular tools to deal with such large-scale sparse data. This paper presents a novel dual coordinate descent method for linear SVM with L1- and L2- loss functions. The proposed method is sim- ple and reaches

  13. P-packSVM: Parallel Primal grAdient desCent Kernel SVM

    Microsoft Academic Search

    Zeyuan Allen Zhu; Weizhu Chen; Gang Wang; Chenguang Zhu; Zheng Chen

    2009-01-01

    It is an extreme challenge to produce a nonlinear SVM classifier on very large scale data. In this paper we describe a novel P-packSVM algorithm that can solve the support vector machine (SVM) optimization problem with an arbitrary kernel. This algorithm embraces the best known stochastic gradient descent method to optimize the primal objective, and has 1\\/ż dependency in complexity

  14. A Critical Analysis of Western Perspectives on Families of Arab Descent

    ERIC Educational Resources Information Center

    Beitin, Ben K.; Allen, Katherine R.; Bekheet, Maureen

    2010-01-01

    Western research on families of Arab descent has increased in the current decade, compared to the previous 30 years. In this review of 256 empirical articles, through a critical postcolonial lens, domestic violence and family planning were the two most established areas of study. Generally, samples have come from a small group of countries such as…

  15. Stochastic Gradient Descent for Non-smooth Optimization: Convergence Results and Optimal Averaging Schemes

    E-print Network

    Zhang, Tong

    , USA Abstract Stochastic Gradient Descent (SGD) is one of the simplest and most popular stochas- tic of SGD with non-smooth objective functions such as support vector machines. In this paper, we investigate the performance of SGD without such smoothness assumptions, as well as a running average scheme to convert the SGD

  16. HOGWILD!: A Lock-Free Approach to Parallelizing Stochastic Gradient Descent

    E-print Network

    Pratt, Vaughan

    Descent (SGD) is a popular algorithm that can achieve state- of-the-art performance on a variety of machine learning tasks. Several researchers have recently proposed schemes to parallelize SGD, but all theoretical analysis, algorithms, and implementation that SGD can be im- plemented without any locking. We

  17. Efficient Low-Rank Stochastic Gradient Descent Methods for Solving Semidefinite Programs

    E-print Network

    , CA 95014 Abstract We propose a low-rank stochastic gradient descent (LR-SGD) method for solving a class of semidefinite programming (SDP) prob- lems. LR-SGD has clear computational ad- vantages over the standard SGD peers as its iterative projection step (a SDP prob- lem) can be solved in an efficient manner

  18. Reflections on Speech Motor Control Based on Phonatory and DDK Tasks in Dysarthric Subjects with Lesions in Different Cerebellar Loci

    ERIC Educational Resources Information Center

    Vandana, V. P.

    2007-01-01

    There are very few acoustic studies reflecting on the localization of speech function within the different loci of the cerebellum. Task based performance profile of subjects with lesion in different cerebellar loci is not reported. Also, the findings on nonfocal cerebellar lesions cannot be generalized to lesions restricted to the cerebellum.…

  19. The Regulatory Connection between the Activity of Granule Cell NMDA Receptors and Dendritic Differentiation of Cerebellar Purkinje Cells

    Microsoft Academic Search

    Hirokazu Hirai; Thomas Launey

    2000-01-01

    It is known that cerebellar granule cells are powerful inducers for the differentiation of Purkinje cells. However, the detailed mech- anism of this regulation has not yet been clarified. Here, using cerebellar neuronal culture, we show that the activation of NMDA receptors expressed by granule cells triggers the signaling path- way for the dendritic differentiation of Purkinje cells. This signal

  20. Molecular, Topographic, and Functional Organization of the Cerebellar Cortex: A Study with Combined Aldolase C and Olivocerebellar Labeling

    Microsoft Academic Search

    Izumi Sugihara; Yoshikazu Shinoda

    2004-01-01

    Aldolase C (zebrin) expression in Purkinje cells reveals stripe-shaped compartments in the cerebellar cortex. However, it is not clear how these compartments are related to cerebellar functional localization. Therefore, we identified olivocerebellar projections to aldolase C compartments by labeling climbing fibers with biotinylated dextran injected into various small areas within the inferior olive in rats. Specific rostral and caudal aldolase