Sample records for cerebellar tonsillar descent

  1. Symptomatic tonsillar ectopia

    PubMed Central

    Furuya, K.; Sano, K.; Segawa, H.; Ide, K.; Yoneyama, H.

    1998-01-01

    OBJECTIVE—To determine if slight descent of the cerebellar tonsils (< 5 mm below the foramen magnum; tonsillar ectopia) may cause surgically treatable symptomatology.?METHODS—A consecutive series of nine symptomatic patients with tonsillar ectopia seen between December 1990 and March 1993 are reported on. The same number of age and sex matched controls were selected at random from outpatients. Twelve asymptomatic subjects with tonsillar ectopia were found among 5000 people between January 1991 and March 1996. Diagnosis of tonsillar ectopia was based on midsagittal MRI.?RESULTS—Patients presented mainly with chronic intractable occipital dull pain, vertigo, and dysequilibrium. In all patients MRI showed normal brain structure except for tonsillar ectopia (-2.9 (SD 0.8) mm), which has historically been thought to be of no clinical relevance. In the control group the tonsilar position was +2.1 (SD 2.8) mm (p<0.01). Neurotologically abnormal findings were detected with a monaural speech integration test (100%), eye tracking test (56%), optokinetic nystagmus test (89%), and visual suppression test (67%) which strongly suggested a CNS lesion. In accordance with the results of MRI and precise neurotological examination, posterior fossa decompression surgery was carried out, followed by improvement of preoperative symptoms and less severity of neurotological abnormalities in all patients.?CONCLUSION—Tonsillar ectopia could cause neurological symptoms in small populations, which were surgically treatable. Neurotological assessment was necessary to verify the aetiological relation between tonsillar ectopia and various symptoms.?? PMID:9489535

  2. 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

  3. Relationship of syrinx size and tonsillar descent to spinal deformity in Chiari malformation Type I with associated syringomyelia

    PubMed Central

    Godzik, Jakub; Kelly, Michael P.; Radmanesh, Alireza; Kim, David; Holekamp, Terrence F.; Smyth, Matthew D.; Lenke, Lawrence G.; Shimony, Joshua S.; Park, Tae Sung; Leonard, Jeffrey; Limbrick, David D.

    2014-01-01

    Object Chiari malformation Type I (CM-I) is a developmental abnormality often associated with a spinal syrinx. Patients with syringomyelia are known to have an increased risk of scoliosis, yet the influence of specific radiographically demonstrated features on the prevalence of scoliosis remains unclear. The primary objective of the present study was to investigate the relationship of maximum syrinx diameter and tonsillar descent to the presence of scoliosis in patients with CM-I–associated syringomyelia [AQ? Edit okay? If not, please advise. JG: edit correct]. A secondary objective was to explore the role of craniovertebral junction (CVJ) characteristics for additional risk factors for scoliosis. Methods The authors conducted a retrospective review of pediatric patients evaluated for CM-I with syringomyelia at a single institution in the period from 2000 to 2012. Syrinx morphology and CVJ parameters were evaluated with MRI, whereas the presence of scoliosis was determined using standard radiographic criteria. Multiple logistic regression was used to analyze radiological features that were independently associated with scoliosis. Results Ninety-two patients with CM-I and syringomyelia were identified. The mean age was 10.5 ± 5 years. Thirty-five (38%) of 92 patients had spine deformity; 23 (66%) of these 35 were referred primarily for deformity, and 12 (34%) were diagnosed with deformity during workup for other symptoms. Multiple regression analysis revealed maximum syrinx diameter > 6 mm (OR 12.1, 95% CI 3.63–40.57, p < 0.001) and moderate (5–12 mm) rather than severe (> 12 mm) tonsillar herniation (OR 7.64, 95% CI 2.3–25.31, p = 0.001) as significant predictors of spine deformity when controlling for age, sex, and syrinx location. Conclusions The current study further elucidates the association between CM-I and spinal deformity by defining specific radiographic characteristics associated with the presence of scoliosis. Specifically, patients presenting with larger maximum syrinx diameters (> 6 mm) have an increased risk of scoliosis. PMID:24527859

  4. 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. PMID:25811002

  5. Cerebellar Astrocytomas

    Microsoft Academic Search

    David F. Bauer; John C. Wellons

    \\u000a The term cerebellar astrocytoma typically refers to the WHO grade I lesion within the cerebellum known also as a cerebellar\\u000a pilocytic astrocytoma or cerebellar juvenile pilocytic astrocytoma (JPA). However, cerebellar astrocytomas may be fibrillary\\u000a instead of pilocytic or may show more malignant histological characteristics. Although pilocytic astrocytomas may occur throughout\\u000a the brain or spinal cord, they mainly occur in the

  6. [Palatine tonsil lymphoma in children with tonsillar asymmetry. Case report].

    PubMed

    Cuestas, Giselle; Martínez Font, Agustín; Demarchi, María Victoria; Martínez Corvalán, María Pía; García Rivello, Hernán; Morandi, Ana; Razetti, Juan; Boccio, Carlos

    2015-08-01

    Tonsil malignancy is uncommon in children. Tonsillar asymmetry is usually secondary to a benign process, either inflammatory conditions, differences in the tonsillar fossa depth or anterior pillar asymmetry. However, it may indicate a serious underlying disorder such as lymphoma. Lymphoma is the most common childhood malignancy in the head and neck. Approximately, 15% of the cases affect the Waldeyer's ring. The most common clinical manifestations of palatine tonsils lymphoma are unilateral tonsillar hypertrophy, alteration in the appearance of the mucosa and ipsilateral cervical lymphadenopathy. Early diagnosis and appropriate treatment are of great importance in the prognosis. We present a case of palatine tonsil lymphoma in a child with tonsillar asymmetry and we emphasize the importance of the examination of the oral cavity and the neck to identify suspicious alterations compatible with tonsillar lymphoma. PMID:26172022

  7. Steepest Descent

    SciTech Connect

    Meza, Juan

    2010-02-12

    The steepest descent method has a rich history and is one of the simplest and best known methods for minimizing a function. While the method is not commonly used in practice due to its slow convergence rate, understanding the convergence properties of this method can lead to a better understanding of many of the more sophisticated optimization methods. Here, we give a short introduction and discuss some of the advantages and disadvantages of this method. Some recent results on modified versions of the steepest descent method are also discussed.

  8. Descent vehicles

    NASA Technical Reports Server (NTRS)

    Popov, Y. I.

    1985-01-01

    The creation of descent vehicles marked a new stage in the development of cosmonautics, involving the beginning of manned space flight and substantial progress in space research on the distant bodies of the Solar System. This booklet describes these vehicles and their structures, systems, and purposes. It is intended for the general public interested in modern problems of space technology.

  9. Cerebellar Degeneration

    MedlinePLUS

    ... in which cerebellar degeneration is a key feature Friedreich’s ataxia, and other spinocerebellar ataxias, which are caused by ... Tel: 763-553-0020 Fax: 763-553-0167 Friedreich's Ataxia Research Alliance (FARA) P.O. Box 1537 Springfield, ...

  10. Cerebellar lesion.

    PubMed

    Cardenas, Raul; Chittiboina, Prashant; Willis, Brian K; Gonzalez-Toldeo, Eduardo; Nanda, Anil

    2010-01-01

    Lhermitte-Duclos disease is a rare cerebellar lesion that poses many diagnostic, pathophysiologic and therapeutic conundrums. Here we present a case that highlights the most important imaging characteristics for diagnosis, the pathophysiology of the disease, and the current management recommendations. PMID:20666170

  11. Lack of lymphoid cell apoptosis in the pathogenesis of tonsillar hypertrophy as compared to recurrent tonsillitis

    Microsoft Academic Search

    M. A. López-González; P. Díaz; F. Delgado; M. Lucas

    1999-01-01

    he pathogenic mechanism of tonsillar hypertrophy is unknown and lacks a proper infectious or immunological explanation. Epidemiological\\u000a studies point to polluted environments as the main cause of tonsillar hypertrophy in the adaptation of the juvenile organism.\\u000a Tonsils and adenoids of 67 children aged 2–16 years (mean 5.9 years) were divided into three groups: recurrent tonsillitis\\u000a (n=21), recurrent tonsillitis with tonsillar

  12. Scar contracture of anterior tonsillar pillar leading to difficult intubation

    PubMed Central

    Kapoor, Hemlata; Mokashi, Suhas

    2014-01-01

    Unanticipated difficult intubations on the operation table have often tested all the anesthetists’ intubation skill. The understanding of the causative factor and accordingly using the correct instrument from the difficult intubation kit requires experience and thorough knowledge on the part of the anesthetist. We describe a case of difficult intubation due to scar contracture of anterior tonsillar pillar formed after a previous surgery. PMID:25886119

  13. Scar contracture of anterior tonsillar pillar leading to difficult intubation.

    PubMed

    Kapoor, Hemlata; Mokashi, Suhas

    2014-01-01

    Unanticipated difficult intubations on the operation table have often tested all the anesthetists' intubation skill. The understanding of the causative factor and accordingly using the correct instrument from the difficult intubation kit requires experience and thorough knowledge on the part of the anesthetist. We describe a case of difficult intubation due to scar contracture of anterior tonsillar pillar formed after a previous surgery. PMID:25886119

  14. MRI in cerebellar hypoplasia

    Microsoft Academic Search

    N. deSouza; R. Chaudhuri; J. Bingham; T. Cox

    1994-01-01

    Cerebellar hypoplasia may present with a wide variety of neurological and systemic features, ranging from aplasia causing neonatal death to mild hypoplasia in an asymptomatic adult. MRI clearly documents the size of the cerebellum and any associated abnormalities. We describe 7 cases of cerebellar hypoplasia of varying aetiology-3 inherited, 2 associated with spinal dysraphism, 1 with Joubert's syndrome and 1

  15. Asymptomatic tonsillar herniation in a neonate with cleidocranial dysplasia.

    PubMed

    Myers, Kenneth A; Thomas, Mary Ann; Wei, Xing-Chang; Scantlebury, Morris H

    2014-02-01

    A male neonate was antenatally diagnosed with cleidocranial dysplasia on the basis of prenatal ultrasound findings and molecular testing of the RUNX2 gene. The patient presented with urosepsis at 24 days of life and subsequently developed apneas after endoscopic examination of the vocal cords. Computed tomography and MRI studies of the head revealed crowding of the posterior fossa with tonsillar and uncal herniation. Apneas were initially thought to be related to brainstem compression; however, the patient responded immediately to caffeine and subsequently stabilized with antibiotic therapy. To our knowledge, this is the first published MRI study of the brain of a neonate with cleidocranial dysplasia to demonstrate the striking posterior fossa findings seen secondary to the reduced bony skull structures. However, despite the dramatic herniation, brainstem function was not compromised. PMID:24446448

  16. Acute cerebellar ataxia

    MedlinePLUS

    ... weeks after an illness caused by a virus. Viral infections that may cause this include chickenpox , Coxsackie disease, ... multiple sclerosis) Cerebellar ataxia caused by a recent viral infection may not need treatment.

  17. 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

  18. Factors controlling testis descent.

    PubMed

    Hughes, Ieuan A; Acerini, Carlo L

    2008-12-01

    Descent of the testis from an intra-abdominal site in foetal life to an extracorporeal location after birth is a mandatory developmental process to ensure that the mature testis promotes normal spermatogenesis. The two phases of transabdominal and inguinoscrotal descent occur approximately during the first and last thirds of gestation respectively. Key anatomical events to release the testis from its urogenital ridge location and to guide the free gonad into the scrotum are the degeneration of the cranio-suspensory ligament and a thickening of the gubernaculum. Androgens play a role in both these processes, particularly with respect to enabling the testis to traverse the inguinal canal in the final phase of descent. Experiments in animals suggest that androgens mediate this effect via the release of calcitonin gene-related peptide by the genitofemoral nerve, but direct evidence for such a mechanism is lacking in humans. The transabdominal phase of descent is under the control of insulin-like 3 (INSL3), a product of the Leydig cells. Definitive evidence of its role in rodent testis descent is illustrated by the phenotype of bilateral cryptorchidism in Insl3-/- null mice. Circulating levels of INSL3 are higher in boys at puberty, are undetectable in girls and are lower in boys with undescended testes. A minority also have a mutation either in the INSL3 gene or affecting its receptor gene, relaxin/insulin-like family peptide receptor 2 (LGRF8). Other factors that may play a role in testis descent include the anti-Mullerian hormone and members of the HOX gene family. Evidence that the prevalence of undescended testis may be increasing provides a phenotypic readout for the effects of postulated chemicals in the environment interfering in some way with the action of factors that control testis descent. Epidemiological studies point to profound geographical variations in prevalence in countries such as Denmark and Finland. Associations have been found with levels of chemicals labelled as endocrine disruptors being higher in breast milk samples from mothers with cryptorchid boys when compared with controls. The adverse effects of these compounds (e.g. bisphenol A) can be replicated in the offspring of dams exposed during pregnancy. A sensitive marker of an anti-androgen effect of a compound is a reduction in the anogenital distance, an anthropometric measurement that is significantly greater in males compared with females. The observation of an association between the anogenital distance in infant boys and the level of pesticides in the urine of their mothers in late gestation indicates that this has the potential to be a useful surrogate marker of the effects of environmental chemicals on testis descent in human population studies. The rightful place for the testis at birth is in the scrotum in order to provide the temperature differential essential for normal spermatogenesis. Appropriate screening programmes and early surgical intervention are the prerequisites to ensure optimal fertility in adulthood and a considerably lessened risk of testis cancer. PMID:18647820

  19. [Latent otogenic cerebellar abscess].

    PubMed

    Szmeja, Z; Kulczy?ski, B; Pabiszczak, M

    2001-01-01

    A case of latent otogenic cerebellar abscess is presented during chronic otitis media with cholesteatoma, in 42-year-old woman. Good results of the treatment were obtained by draining and substituting the content of abscess into antibiotic solution. PMID:11766321

  20. Immune response of tonsillar lymphocytes to Haemophilus parainfluenzae in patients with IgA nephropathy

    PubMed Central

    Suzuki, S; Fujieda, S; Sunaga, H; Sugimoto, H; Yamamoto, C; Kimura, H; Abo, T; Gejyo, F

    2000-01-01

    The pathogenesis of IgA nephropathy (IgAN) is unclear. We have previously shown glomerular deposition of Haemophilus parainfluenzae (HPI) antigens and the presence of IgA antibody against HPI antigens in patients with IgAN. We examined the immune response to HPI antigens in tonsillar lymphocytes from patients with IgAN. Lymphocytes isolated from the palatine tonsils of 13 IgAN patients and 16 patients with chronic tonsillitis but without renal disease were used as controls. We examined lymphocyte proliferation and production of IgA antibody against HPI antigens by measuring thymidine uptake and IgA antibody in culture supernatants after lymphocyte incubation with HPI antigens. Patients with IgAN showed a significantly higher stimulation index to HPI antigens (thymidine incorporation in tonsillar lymphocytes with HPI/thymidine incorporation in unstimulated tonsillar lymphocytes) than controls (P < 0.002). Lymphocytes from patients with IgAN also showed a significantly higher level of IgA antibody and IgA1 antibody against HPI antigens in culture supernatants than lymphocytes from controls (P = 0.0002 and P = 0.004, respectively). Our results suggest that HPI antigens stimulate tonsillar T and B lymphocytes in patients with IgAN and that an immune response to HPI antigens may play a role in the pathogenesis of this disease in some cases. PMID:10632671

  1. Chronic tonsillar enlargement and cough: preliminary evidence of a novel and treatable cause of chronic cough

    Microsoft Academic Search

    S. S. Birring; C. Passant; R. B. Patel; B. Prudon; G. E. Murty; I. D. Pavord

    2004-01-01

    Tonsillar enlargement is sometimes seen in patients with otherwise unexplained chronic cough although its significance is unclear. In this study, the authors set out to test the hypothesis that cough symptoms and cough reflex sensitivity will improve after tonsillectomy in patients with otherwise unexplained chronic cough and enlarged tonsils. Eight consecutive patients with unexplained chronic cough and enlarged tonsils were

  2. Prevalence of tonsillar hypertrophy and associated oropharyngeal symptoms in primary school children in Denizli, Turkey

    Microsoft Academic Search

    Cüneyt Orhan Kara; Hacer Ergin; Gülendam Koçak; ?lknur K?l?ç; Merve Yurdakul

    2002-01-01

    Objective: The purpose of this study is to investigate the prevalence of tonsillar hypertrophy and associated oropharyngeal symptoms in primary school children. Methods: The study was performed in two primary schools which were chosen randomly in Denizli. Size of the tonsils was evaluated and scored on a five-point scale and weights of children were measured. The mothers or primary caregivers

  3. The relationship of tonsillar hyperplasia and asthma in a group of asthmatic children

    Microsoft Academic Search

    Ömer Ceran; Sibel Aka; Devrim Öztemel; Burcu Uyanik; Tamay Özkozaci

    2004-01-01

    Background: The decline of infections in childhood may contribute to the rising severity and prevalence of atopic disorders in developed countries. With this regard, we examined the relationship of frequent tonsillitis and consequent tonsillar hyperplasia with the development of asthma. Methods: Sixty-seven asthmatic children (ages 3–14) who had no signs or symptoms of acute tonsillitis were included. The control group

  4. 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...

  5. Cerebellar function in developmental dyslexia.

    PubMed

    Stoodley, Catherine J; Stein, John F

    2013-04-01

    Developmental dyslexia is a genetically based neurobiological syndrome, which is characterized by reading difficulty despite normal or high general intelligence. Even remediated dyslexic readers rarely achieve fast, fluent reading. Some dyslexics also have impairments in attention, short-term memory, sequencing (letters, word sounds, and motor acts), eye movements, poor balance, and general clumsiness. The presence of "cerebellar" motor and fluency symptoms led to the proposal that cerebellar dysfunction contributes to the etiology of dyslexia. Supporting this, functional imaging studies suggest that the cerebellum is part of the neural network supporting reading in typically developing readers, and reading difficulties have been reported in patients with cerebellar damage. Differences in both cerebellar asymmetry and gray matter volume are some of the most consistent structural brain findings in dyslexics compared with good readers. Furthermore, cerebellar functional activation patterns during reading and motor learning can differ in dyslexic readers. Behaviorally, some children and adults with dyslexia show poorer performance on cerebellar motor tasks, including eye movement control, postural stability, and implicit motor learning. However, many dyslexics do not have cerebellar signs, many cerebellar patients do not have reading problems, and differences in dyslexic brains are found throughout the whole reading network, and not isolated to the cerebellum. Therefore, impaired cerebellar function is probably not the primary cause of dyslexia, but rather a more fundamental neurodevelopmental abnormality leads to differences throughout the reading network. PMID:22851215

  6. Tonsillotomy or tonsillectomy?—a prospective study comparing histological and immunological findings in recurrent tonsillitis and tonsillar hyperplasia

    Microsoft Academic Search

    Oliver Reichel; Doris Mayr; Jan Winterhoff; Richard de la Chaux; Hjalmar Hagedorn; Alexander Berghaus

    2007-01-01

    We evaluated the differences in histological and immunological findings in children with recurrent tonsillitis and tonsillar\\u000a hyperplasia and assessed the risk for relapsing tonsillar hyperplasia or recurrent tonsillitis after tonsillotomy in a prospective\\u000a clinical study. Sixty-four children with recurrent tonsillitis underwent traditional (total) blunt dissection tonsillectomy\\u000a between October 2003 and July 2004. Partial tonsillectomy (tonsillotomy) using CO2-laser technique was performed

  7. Toxic agents causing cerebellar ataxias

    Microsoft Academic Search

    Mario Manto

    2011-01-01

    The cerebellum is particularly vulnerable to intoxication and poisoning, especially so the cerebellar cortex and Purkinje neurons. In humans, the most common cause of a toxic lesion to the cerebellar circuitry is alcohol related, but the cerebellum is also a main target of drug exposure (such as anticonvulsants, antineoplastics, lithium salts, calcineurin inhibitors), drug abuse and addiction (such as cocaine,

  8. Cerebellar agenesis revisited.

    PubMed

    Boyd, C A R

    2010-03-01

    New clinical and employment information, together with over-looked previously published information, on a patient (H.C.) is reviewed. H.C., who died at the age of 76 in 1939, was found, by chance during anatomical dissection, to lack a cerebellum. This synthesis challenges an unusual and interesting account of cerebellar agenesis published in Brain in 1994 by Glickstein (see also Glickstein, 2006), in which the allegedly 'bogus' oral history of this individual's motor skills was held to have led to 'medical myth making'. Part of the burden of the 1994 paper was to show that 'cerebellar agenesis is always associated with profound motor deficits'. Glickstein therefore focussed on an apparent 'exception' to this conclusion, concerning the brain of a single case, H.C., who died 70 years ago, who 'had given rise to an oral tradition alleging that normal movement is possible despite total cerebellar agenesis'. Glickstein (1994) concludes 'despite an oral tradition to the contrary there is absolutely no evidence about the motor capacities of this man during his life'. Rather remarkably, an extensive history of this individual has become available, its significance becoming noted only this year; this complements and adds to a previous brief history published on H.C. (and not mentioned in the 1994 paper; see below). The new evidence includes the death certificate stating the man's occupation to have been 'manual labourer' with all the implications relevant to his supposed incapacity. The written historical record thus confronts the alleged 'myth'. It is interesting to note how medical records on an undoubtedly very ordinary citizen were recorded in London in the 1930s (before the NHS was set up in 1949) and how they could be made accessible to clinical colleagues in east London in the middle of World War II blitz bombing of the capital. PMID:19843649

  9. 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.

  10. 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

  11. Lunar Module Descent Mission Design

    Microsoft Academic Search

    Alan W. Wilhite; John Wagner; Robert Tolson; Marina Mazur Moen

    2008-01-01

    Various lunar descent trajectories were analyzed that include the optimization of the Apollo constrained mission trajectory, a fully optimized minimum energy trajectory, and a optimal, constrained trajectory using current instrumentation technology. Trade studies were conducted to determine the impacts of mission assumptions, pilot in the loop\\/automated flight demands, and additional constraints for the present recurring missions to the same outpost

  12. Alcohol Withdrawal and Cerebellar Mitochondria.

    PubMed

    Jung, Marianna E

    2015-08-01

    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

  13. The compartmental restriction of cerebellar interneurons

    PubMed Central

    Consalez, G. Giacomo; Hawkes, Richard

    2013-01-01

    The Purkinje cells (PC's) of the cerebellar cortex are subdivided into multiple different molecular phenotypes that form an elaborate array of parasagittal stripes. This array serves as a scaffold around which afferent topography is organized. The ways in which cerebellar interneurons may be restricted by this scaffolding are less well-understood. This review begins with a brief survey of cerebellar topography. Next, it reviews the development of stripes in the cerebellum with a particular emphasis on the embryological origins of cerebellar interneurons. These data serve as a foundation to discuss the hypothesis that cerebellar compartment boundaries also restrict cerebellar interneurons, both excitatory [granule cells, unipolar brush cells (UBCs)] and inhibitory (e.g., Golgi cells, basket cells). Finally, it is proposed that the same PC scaffold that restricts afferent terminal fields to stripes may also act to organize cerebellar interneurons. PMID:23346049

  14. Tonsillar Biopsy Test for Chronic Wasting Disease: Two Sampling Approaches in Mule Deer and White-tailed Deer

    Microsoft Academic Search

    Krysten L. Schuler; Jonathan A. Jenks; Christopher S. DePerno; Margaret A. Wild

    Preclinical antemortem testing of deer (Odocoileus spp.) for chronic wasting dis- ease (CWD) can be important for determining prevalence rates and removing infected individ- uals from wild populations. Because samples with high numbers of tonsillar follicles are like- ly to provide earlier detection of CWD than samples with fewer follicles, the method of ob- taining follicular samples may be critical

  15. Cerebellar connections in Xenopus laevis

    Microsoft Academic Search

    A. Gonzalez; H. J. Donkelaar; R. de Boer-van Huizen

    1984-01-01

    In the present study the cerebellar afferents in the clawed toad Xenopus laevis have been analysed with the horseradish peroxidase (HRP) technique. In addition, data on the efferent connections of the cerebellum could be gathered, based on the phenomenon of anterograde transport of HRP.

  16. 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

  17. 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

  18. 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.

  19. Tonsillar calculi. Report of a case and review of the literature.

    PubMed

    Cooper, M M; Steinberg, J J; Lastra, M; Antopol, S

    1983-03-01

    A large tonsillar calculus in a 77-year-old demented woman with a history of chronic oral infections and multiple episodes of pneumonia is reported. Earlier literature describes these calcium-laden tonsilloliths as occurring in adolescence following chronic tonsillitis. Improvement in health care of the young and antibiosis militate against tonsilloliths as a serious problem in the young patient. Conversely, an ever-increasing aged population, with impaired self-care abilities or diminished cerebral function, many of whom populate nursing care facilities, and increased routine oropharyngeal screening of the aged may add significantly to the number of reported cases. In view of the potential for continuous oropharyngeal disease and the possibilities of swallowing disturbances, pneumonia, or food or liquid aspiration, which may result in lethal complications the authors urge the clinician to assess masses or calcified objects viewed on physical examination or radiographs, explore their etiology, evaluate them for removal, and not dismiss them as clinically insignificant. PMID:6572876

  20. Palatine Tonsillar Metastasis of Small-Cell Neuroendocrine Carcinoma from the Lung Detected by FDG-PET/CT After Tonsillectomy: A Case Report

    PubMed Central

    Chen, Xiao-Hong; Bao, Yang-Yang; Zhou, Shui-Hong; Wang, Qin-Ying; Zhao, Kui

    2013-01-01

    Metastasis from a malignant tumor to the palatine tonsils is rare, accounting for only 0.8% of all tonsillar tumors, with only 100 cases reported in the English-language literature. Various malignant lung carcinomas may metastasize to the tonsils. A few cases of tonsillar metastasis from neuroendocrine lung carcinoma have been reported. A 67-year-old female underwent a right tonsillectomy because of a sore throat and an enlarged right tonsil. The postoperative pathology showed right tonsillar small cell neuroendocrine carcinoma (SCNC). Fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) demonstrated metabolic activity in the lower lobe of the right lung. In addition, hypermetabolic foci were noted in the lymph nodes of the right neck and mediastinum. A needle biopsy of the pulmonary mass showed SCNC. The patient received chemotherapy and died of multiple distant metastases after 6 months. This is the first report using PET/CT to evaluate tonsillar metastasis from lung SCNC. PMID:24348600

  1. 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.

  2. 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.

  3. Mechanisms of cerebellar gait ataxia

    Microsoft Academic Search

    Susanne M. Morton; Amy J. Bastian

    2007-01-01

    The cerebellum is important for movement control and plays a critical role in balance and locomotion. As such, one of the\\u000a most characteristic and sensitive signs of cerebellar damage is gait ataxia. How the cerebellum normally contributes to locomotor\\u000a behavior is unknown, though recent work suggests that it helps generate appropriate patterns of limb movements, dynamically\\u000a regulate upright posture and

  4. 43 CFR 10.14 - Lineal descent and cultural affiliation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...procedures for determining lineal descent and cultural affiliation...Criteria for determining lineal descent. A lineal descendant...manufacture and distribution methods for the earlier group, or...Standard of proof. Lineal descent of a present-day...

  5. 43 CFR 10.14 - Lineal descent and cultural affiliation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...procedures for determining lineal descent and cultural affiliation...Criteria for determining lineal descent. A lineal descendant...manufacture and distribution methods for the earlier group, or...Standard of proof. Lineal descent of a present-day...

  6. Cerebellar malformations: some pathogenetic considerations.

    PubMed

    Urich, H

    1979-01-01

    1) Destructive processes are responsible for most cases of cerebellar microgyria of the trabecular pattern. Erosion and subsequent fusion of the folia produce the disorganized pattern in which the various cellular elements retain their noraml relationship and are capable of normal maturation. Intrauterine infection is responsible for most cases; the evidence is conclusive in some cases, presumptive in others. 2) Faulty genetic coding, as illustrated by the trisomies, may lead to formation of heterotopias. The primitive cells aggregating around the dentate nucleus should be interpreted as matrix cells and not as cells of the external granular layer. Cortical heterotopias with attempted internal organisation also occur; their origin is obscure. The unusual, possibly unique, transposition of the internal granular and Purkinje cell layers observed in one case may be ascribed to faulty formation of the Bergmann glia by analogy with the weaver mouse. 3) It is impossible at present to disentangle the role of genetic and environmental factors in the pathogenesis of the hysraphic malformations. It is possible, however, that defective fusion of the intraventricular cerebellar primordium plays a part in the development of the Dandy-Walker malformation, of midine cerebellar clefts in some cases of occipital encephalocele, and of extra-axial ependymal cysts of the posterior fossa. PMID:233076

  7. (Co)Simplicial Descent Categories

    E-print Network

    Gonzalez, Beatriz Rodriguez

    2008-01-01

    This paper contains the notion of simplicial descent category. Such a category D is endowed with a class of equivalences and a `simple functor' from the category of simplicial objects in D to D. They are presented as a complementary tool to study the associated homotopy category. Some examples of such simple functors are the total complex of a double complex, the (fat) geometric realization, Deligne's simple of mixed Hodge complexes and Navarro's Thom-Whitney simple of commutative differential graded algebras. They (and other related simples), provide simplicial descent structures on the categories of chain complexes over an additive/abelian category, simplicial sets, topological spaces, filtered cochain complexes, differential graded algebras over a commutative ring, commutative differential graded algebras over a field of characteristic 0, DG-modules over a DG-category and mixed Hodge complexes. We summarize (and improve) here part of author's Ph.D. thesis (arXiv:0804.2154v1). The factorization axiom of sim...

  8. 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.

  9. Setup deviations in wedged pair irradiation of parotid gland and tonsillar tumors, measured with an electronic portal imaging device

    Microsoft Academic Search

    A. Bel; R. Keus; R. E. Vijlbrief; J. V. Lebesque

    1995-01-01

    The first aim of this study was to quantify estimated translational setup deviations of patients treated with a wedged pair of oblique beams for parotid gland and tonsillar tumors, using portal imaging. The second aim was to design an off-line setup verification procedure, to improve the setup accuracy, if necessary. Thirty-one patients were treated with two conformal fields (anterior-oblique and

  10. 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

  11. 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…

  12. Cerebellar Stroke-manifesting as Mania.

    PubMed

    Jagadesan, Venkatesan; Thiruvengadam, Kannapiran R; Muralidharan, Rengarajalu

    2014-07-01

    Secondary mania resulting from cerebral Cortex are described commonly. But secondary mania produced by cerebellar lesions are relatively uncommon. This case report describes a patient who developed cerebellar stoke and manic features simultaneously. 28 years old male developed giddiness and projectile vomiting. Then he would lie down for about an hour only to find that he could not walk. He became quarrelsome. His Psycho motor activities and speech were increased. He was euphoric and was expressing grandiose ideas. Bender Gestalt Test showed signs of organicity. Score in Young mania relating scale was 32; productivity was low in Rorschach. Neurological examination revealed left cerebellar signs like ataxia and slurring of speech. Computed tomography of brain showed left cerebellar infarct. Relationship between Psychiatric manifestations and cerebellar lesion are discussed. PMID:25035567

  13. Cellular and molecular basis of cerebellar development

    PubMed Central

    Martinez, Salvador; Andreu, Abraham; Mecklenburg, Nora; Echevarria, Diego

    2013-01-01

    Historically, the molecular and cellular mechanisms of cerebellar development were investigated through structural descriptions and studying spontaneous mutations in animal models and humans. Advances in experimental embryology, genetic engineering, and neuroimaging techniques render today the possibility to approach the analysis of molecular mechanisms underlying histogenesis and morphogenesis of the cerebellum by experimental designs. Several genes and molecules were identified to be involved in the cerebellar plate regionalization, specification, and differentiation of cerebellar neurons, as well as the establishment of cellular migratory routes and the subsequent neuronal connectivity. Indeed, pattern formation of the cerebellum requires the adequate orchestration of both key morphogenetic signals, arising from distinct brain regions, and local expression of specific transcription factors. Thus, the present review wants to revisit and discuss these morphogenetic and molecular mechanisms taking place during cerebellar development in order to understand causal processes regulating cerebellar cytoarchitecture, its highly topographically ordered circuitry and its role in brain function. PMID:23805080

  14. 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

  15. 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

  16. Cerebellar involvement in metabolic disorders: a pattern-recognition approach

    Microsoft Academic Search

    M. Steinlin; S. Blaser; E. Boltshauser

    1998-01-01

    Inborn errors of metabolism can affect the cerebellum during development, maturation and later during life. We have established\\u000a criteria for pattern recognition of cerebellar abnormalities in metabolic disorders. The abnormalities can be divided into\\u000a four major groups: cerebellar hypoplasia (CH), hyperplasia, cerebellar atrophy (CA), cerebellar white matter abnormalities\\u000a (WMA) or swelling, and involvement of the dentate nuclei (DN) or cerebellar

  17. Descent heuristics for unconstrained minimization 1 Introduction

    E-print Network

    2008-08-14

    f gets smaller) because negative curvature hints that long descent steps may ..... Network Localization Problems with distance measurements (as described for example .... the Semidefinite Programming Relaxation Solution for Ad Hoc Wireless.

  18. 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.

  19. 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 ...

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Cerebellar vermian hypoplasia in a Cocker Spaniel

    PubMed Central

    Lim, Ji-Hey; Kim, Dae-Yong; Yoon, Jung-hee; Kim, Wan Hee

    2008-01-01

    An eight-week-old female Cocker Spaniel was presented with ataxia, dysmetria and intention tremor. At 16 weeks, the clinical signs did not progress. Investigation including imaging studies of the skull and cerebrospinal fluid analysis were performed. The computed tomography revealed a cyst-like dilation at the level of the fourth ventricle associated with vermal defect in the cerebellum. After euthanasia, a cerebellar hypoplasia with vermal defect was identified on necropsy. A polymerase chain reaction amplification of cerebellar tissue revealed the absence of an in utero parvoviral infection. Therefore, the cerebellar hypoplasia in this puppy was consistent with diagnosis of primary cerebellar malformation comparable to Dandy-Walker syndrome in humans. PMID:18487946

  5. Cerebellar Zones: History, Development, and Function

    Microsoft Academic Search

    John Oberdick; Roy V. Sillitoe

    The longitudinal and transverse zonal arrangement of axonal projections to and from the cerebellum, even more than the well-known\\u000a laminar cytoarchitecture, is the hallmark of cerebellar anatomy. No model of cerebellar function, whether in motor control,\\u000a cognition, or emotion, will be complete without understanding the development and function of zones. To this end, a special\\u000a issue of this journal is

  6. Cerebellar Purkinje cell activity drives motor learning

    PubMed Central

    Nguyen-Vu, T.D.Barbara; Kimpo, Rhea R; Rinaldi, Jacob M; Kohli, Arunima; Zeng, Hongkui; Deisseroth, Karl; Raymond, Jennifer L

    2014-01-01

    The climbing fiber input to the cerebellar cortex is thought to provide instructive signals that drive the induction of motor skill learning. We found that optogenetic activation of Purkinje cells, the sole output neurons of the cerebellar cortex, can also drive motor learning in mice. This dual control over the induction of learning by climbing fibers and Purkinje cells can expand the learning capacity of motor circuits. PMID:24162651

  7. 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.

  8. A single centre experience with sequential and concomitant chemoradiotherapy in locally advanced stage IV tonsillar cancer

    PubMed Central

    2010-01-01

    Background Chemo-radiotherapy offers an alternative to primary surgery and adjuvant therapy for the management of locally advanced stage IV squamous cell carcinomas of the tonsil. Methods A retrospective analysis was performed of the outcomes of 41 patients with locoregionally advanced squamous cell carcinoma of the tonsil treated non-surgically at the Yorkshire Cancer Centre between January 2004 and December 2005. Due to long radiotherapy waiting times, patients received induction chemotherapy with cisplatin and 5-fluorouracil followed by either cisplatin concurrent chemoradiotherapy or radiotherapy alone. Results Median age was 55 years (range 34-76 years) and 28 (68%) patients were male. 35/41 patients (85%) received 2 or more cycles of induction chemotherapy. Following induction chemotherapy, 32/41 patients (78%) had a clinical response. Concomitant chemotherapy was given to 30/41 (73%). All patients received the planned radiotherapy dose with no delays. There were no treatment related deaths. Six (15%) patients had gastrostomy tubes placed before treatment, and 22 (54%) required nasogastric tube placement during or after treatment for nutritional support. 17 patients required unplanned admissions during treatment for supportive care. At 4 months post treatment assessment 35 out of 41 (85%) patients achieved complete clinical and radiographic response. Median follow-up is 38 months (8-61 months). Local and regional control rate in complete responders at 3 years was 91%. Distant metastases have been found in 4 (9.8%) patients. Three year progression-free survival rate in all patients is 75%. The 3-year cause specific survival and overall survival are 75% and 66% respectively. Conclusion Cisplatin-based induction and concurrent chemoradiotherapy provides excellent tumour control with acceptable toxicity for patients with locally advanced tonsillar cancer. PMID:21176154

  9. Marked differences in survival rate between smokers and nonsmokers with HPV 16-associated tonsillar carcinomas.

    PubMed

    Hafkamp, Harriët C; Manni, J J; Haesevoets, A; Voogd, A C; Schepers, M; Bot, F J; Hopman, A H N; Ramaekers, F C S; Speel, Ernst-Jan M

    2008-06-15

    Oncogenic human papillomavirus (HPV) is a causative agent in a subgroup of head and neck carcinomas, particularly tonsillar squamous cell carcinomas (TSCC). This study was undertaken because controversial data exist on the physical status of HPV-DNA and the use of p16(INK4A) overexpression as surrogate HPV marker, and to examine the impact of HPV and tobacco consumption on the clinical course of TSCC. Tissue sections of 81 TSCC were analyzed by HPV 16-specific fluorescence in situ hybridization (FISH) and p16(INK4A)-specific immunohistochemistry. Results were correlated with clinical and demographic data. HPV 16 integration was detected by FISH as punctate signals in 33 out of 81 (41%) TSCC, 32 of which showed p16(INK4A) accumulation. Only 5 out of 48 HPV-negative tumors showed p16(INK4A) immunostaining (p < 0.0001). The presence of HPV furthermore correlates significantly with low tobacco (p = 0.002) and alcohol intake (p = 0.011), poor differentiation grade (p = 0.019), small tumor size (p = 0.024), presence of a local metastasis (p = 0.001) and a decreased (loco)regional recurrence rate (p = 0.039). Statistical analysis revealed that smoking significantly increases the risk of cancer death from TSCC and that non-smoking patients with HPV-containing TSCC show a remarkably better disease-specific survival rate. HPV 16 is integrated in 41% of TSCC and strongly correlates with p16(INK4A) overexpression, implicating the latter to be a reliable HPV biomarker. Patients with HPV-positive tumors show a favorable prognosis as compared to those with HPV-negative tumors, but tobacco use is the strongest prognostic indicator. These findings indicate that oncogenic processes in the tonsils of non-smokers differ from those occurring in smokers, the former being related to HPV 16 infection. PMID:18360824

  10. Accelerating Stochastic Gradient Descent using Predictive Variance Reduction

    E-print Network

    Johnson, Rie

    Accelerating Stochastic Gradient Descent using Predictive Variance Reduction Rie Johnson RJ variance reduction method for stochastic gradient descent which we call stochastic variance reduced convergence asymptotically due to the inherent variance. To remedy this prob- lem, we introduce an explicit

  11. 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...

  12. 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 ...

  13. 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

  14. Post-infarct cerebellar cognitive affective syndrome: a case report

    Microsoft Academic Search

    Ali Jawaid; Muhammad Ameen Rauf; Uzma Usman; Bhojo A Khealani

    2008-01-01

    Post Infarct cerebellar cognitive affective syndrome is a rare disorder, characterized by cognitive impairment in the domains of memory, language, visuo-spatial functioning and affect after cerebellar stroke. We report a case of young female who developed mood alteration and cognitive disturbance following isolated cerebellar infarct. We, therefore, advocate a potential role of cerebellum in regulation of cognition and behaviour in

  15. 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

  16. On the Convergence of Decentralized Gradient Descent

    E-print Network

    Kun Yuan, Qing Ling, Wotao Yin

    2014-02-07

    We study the decentralized gradient descent method in which each agent i ... †W. Yin is with Department of Mathematics, University of California, Los .... The recent research interest in big data processing also motivates ...... these noise-polluted case to design either centralized [13] or decentralized basis pursuit algorithms.

  17. A Descent Rate Control Approach to Developing an Autonomous Descent Vehicle

    NASA Astrophysics Data System (ADS)

    Fields, Travis D.

    Circular parachutes have been used for aerial payload/personnel deliveries for over 100 years. In the past two decades, significant work has been done to improve the landing accuracies of cargo deliveries for humanitarian and military applications. This dissertation discusses the approach developed in which a circular parachute is used in conjunction with an electro-mechanical reefing system to manipulate the landing location. Rather than attempt to steer the autonomous descent vehicle directly, control of the landing location is accomplished by modifying the amount of time spent in a particular wind layer. Descent rate control is performed by reversibly reefing the parachute canopy. The first stage of the research investigated the use of a single actuation during descent (with periodic updates), in conjunction with a curvilinear target. Simulation results using real-world wind data are presented, illustrating the utility of the methodology developed. Additionally, hardware development and flight-testing of the single actuation autonomous descent vehicle are presented. The next phase of the research focuses on expanding the single actuation descent rate control methodology to incorporate a multi-actuation path-planning system. By modifying the parachute size throughout the descent, the controllability of the system greatly increases. The trajectory planning methodology developed provides a robust approach to accurately manipulate the landing location of the vehicle. The primary benefits of this system are the inherent robustness to release location errors and the ability to overcome vehicle uncertainties (mass, parachute size, etc.). A separate application of the path-planning methodology is also presented. An in-flight path-prediction system was developed for use in high-altitude ballooning by utilizing the path-planning methodology developed for descent vehicles. The developed onboard system improves landing location predictions in-flight using collected flight information during the ascent and descent. Simulation and real-world flight tests (using the developed low-cost hardware) demonstrate the significance of the improvements achievable when flying the developed system.

  18. 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…

  19. Cerebellar endocannabinoids: retrograde signaling from purkinje cells.

    PubMed

    Marcaggi, Païkan

    2015-06-01

    The cerebellar cortex exhibits a strikingly high expression of type 1 cannabinoid receptor (CB1), the cannabinoid binding protein responsible for the psychoactive effects of marijuana. CB1 is primarily found in presynaptic elements in the molecular layer. While the functional importance of cerebellar CB1 is supported by the effect of gene deletion or exogenous cannabinoids on animal behavior, evidence for a role of endocannabinoids in synaptic signaling is provided by in vitro experiments on superfused acute rodent cerebellar slices. These studies have demonstrated that endocannabinoids can be transiently released by Purkinje cells and signal at synapses in a direction opposite to information transfer (retrograde). Here, following a description of the reported expression pattern of the endocannabinoid system in the cerebellum, I review the accumulated in vitro data, which have addressed the mechanism of retrograde endocannabinoid signaling and identified 2-arachidonoylglycerol as the mediator of this signaling. The mechanisms leading to endocannabinoid release, the effects of CB1 activation, and the associated synaptic plasticity mechanisms are discussed and the remaining unknowns are pointed. Notably, it is argued that the spatial specificity of this signaling and the physiological conditions required for its induction need to be determined in order to understand endocannabinoid function in the cerebellar cortex. PMID:25520276

  20. 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

  1. Lhermitte-Duclos disease (dysplastic cerebellar gangliocytoma).

    PubMed

    Rafique, Muhammad Zafar

    2005-01-01

    This case report describes an adult male presenting with ataxia. Dysplastic cerebellar gangliocytoma, the Lhermitte-Duclos disease, was diagnosed on neuroimaging. Diagnosis was confirmed on histopathology of surgically removed lesion. Patient underwent an uneventful recovery following operative treatment. PMID:15670528

  2. Optimal spline regression utilizing steepest descent 

    E-print Network

    Flora, Eric Shirley

    1975-01-01

    fit so that the L2 error as a function of the knots is minimized. The method includes a density method to obtain an original guess for the knot placement. This will then be improved upon by applying steepest descent to the L2 error as a function... special thanks goes to Hew L. Packard for the excellent graphics. TABLE OF CONTENTS CHAPTER I. INTRODUCTION Page II. NORMALIZED B-SPLINES-PROPERTIES AND CALCULATIONS. . . 3 1. Introduction . . . . . , , . . . . , . . . 3 2. Divided Differences 3...

  3. Gradient Descent and Radial Basis Functions

    Microsoft Academic Search

    Mercedes Fernández-redondo; Joaquín Torres-sospedra; Carlos Hernández-espinosa

    2006-01-01

    \\u000a In this paper, we present experiments comparing different training algorithms for Radial Basis Functions (RBF) neural networks.\\u000a In particular we compare the classical training which consists of an unsupervised training of centers followed by a supervised\\u000a training of the weights at the output, with the full supervised training by gradient descent proposed recently in same papers.\\u000a We conclude that a

  4. Ageing shows a pattern of cerebellar degeneration analogous, but not equal, to that in patients suffering from cerebellar degenerative disease.

    PubMed

    Hulst, Thomas; van der Geest, Jos N; Thürling, M; Goericke, S; Frens, Maarten A; Timmann, Dagmar; Donchin, Opher

    2015-08-01

    Ageing generally leads to impairments in cognitive function and the ability to execute and learn new movements. While the causes of these impairments are often multi-factorial, integrity of the cerebellum in an elderly population is an important predictive factor of both motor function and cognitive function. A similar association between cerebellar integrity and function is true for cerebellar patients. We set out to investigate the analogies between the pattern of cerebellar degeneration of a healthy ageing population and cerebellar patients. We quantified cerebellar regional volumes by applying voxel-based morphometry (VBM) to a publicly available dataset of MR images obtained in 313 healthy subjects aged between 18 and 96years and a dataset of MR images of 21 cerebellar patients. We observed considerable overlap in regions with the strongest loss of cerebellar volume in the two datasets. In both datasets, the anterior lobe of the cerebellum (lobules I-V) and parts of the superior cerebellum (primarily lobule VI) showed the strongest degeneration of cerebellar volume. However, the most significant voxels in cerebellar patients were shifted posteriorly (lobule VII) compared to the voxels that degenerate most with age in the healthy population. The results showed a pattern of significant degeneration of the posterior motor region (lobule VIIIb) in both groups, and significant degeneration of lobule IX and X in the healthy population, but not in cerebellar patients. Furthermore, we saw strong volumetric degeneration of functionally defined cerebellar regions associated with cerebral somatomotor function in both groups. Predominance of degeneration in the anterior lobe and lobule VI suggests impairment of motor function in both groups, while we suggest that the posterior shift of degeneration in cerebellar patients would be associated with relatively stronger impairment of higher motor function and cognitive function. Thus, these results may explain the specific symptomology associated with cerebellar degeneration in ageing and in cerebellar patients. PMID:25896930

  5. Simulating Descent and Landing of a Spacecraft

    NASA Technical Reports Server (NTRS)

    Balaram, J.; Jain, Abhinandan; Martin, Bryan; Lim, Christopher; Henriquez, David; McMahon, Elihu; Sohl, Garrett; Banerjee, Pranab; Steele, Robert; Bentley, Timothy

    2005-01-01

    The Dynamics Simulator for Entry, Descent, and Surface landing (DSENDS) software performs high-fidelity simulation of the Entry, Descent, and Landing (EDL) of a spacecraft into the atmosphere and onto the surface of a planet or a smaller body. DSENDS is an extension of the DShell and DARTS programs, which afford capabilities for mathematical modeling of the dynamics of a spacecraft as a whole and of its instruments, actuators, and other subsystems. DSENDS enables the modeling (including real-time simulation) of flight-train elements and all spacecraft responses during various phases of EDL. DSENDS provides high-fidelity models of the aerodynamics of entry bodies and parachutes plus supporting models of atmospheres. Terrain and real-time responses of terrain-imaging radar and lidar instruments can also be modeled. The program includes modules for simulation of guidance, navigation, hypersonic steering, and powered descent. Automated state-machine-driven model switching is used to represent spacecraft separations and reconfigurations. Models for computing landing contact and impact forces are expected to be added. DSENDS can be used as a stand-alone program or incorporated into a larger program that simulates operations in real time.

  6. Mars Exploration Entry, Descent and Landing Challenges

    NASA Technical Reports Server (NTRS)

    Braun, Robert D.; Manning, Robert M.

    2006-01-01

    The United States has successfully landed five robotic systems on the surface of Mars. These systems all had landed mass below 0.6 metric tons (t), had landed footprints on the order of hundreds of km and landed at sites below -1.4 km MOLA elevation due the need to perform entry, descent and landing operations in an environment with sufficient atmospheric density. At present, robotic exploration systems engineers are struggling with the challenges of increasing landed mass capability to 0.8 t while improving landed accuracy to tens of km and landing at a site as high as +2 km MOLA elevation for the Mars Science Laboratory project. Meanwhile, current plans for human exploration of Mars call for the landing of 40-80 t surface elements at scientifically interesting locations within close proximity (tens of m) of pre-positioned robotic assets. This paper summarizes past successful entry, descent and landing systems and approaches being developed by the robotic Mars exploration program to increased landed performance (mass, accuracy and surface elevation). In addition, the entry, descent and landing sequence for a human exploration system will be reviewed, highlighting the technology and systems advances required.

  7. Discrimination of ‘Driver’ and ‘Passenger’ HPV in Tonsillar Carcinomas by the Polymerase Chain Reaction, Chromogenic In Situ Hybridization, and p16 INK4a Immunohistochemistry

    Microsoft Academic Search

    Mark Francis Evans; Alisa Matthews; Dina Kandil; Christine Stewart-Crawford Adamson; Winifred Elizabeth Trotman; Kumarasen Cooper

    Human papillomavirus (HPV) positive tonsillar squamous cell carcinoma (TSCC) is associated with a favorable clinical outcome.\\u000a However, the HPV detected in a given tumor may be causal (driver HPV) or an incidental bystander (passenger HPV). There is\\u000a a need to discriminate these forms of HPV in TSCCs to understand their impact on HPV as a biomarker for use in TSCC

  8. Nucleotide-binding and oligomerization domain-like receptors and retinoic acid inducible gene-like receptors in human tonsillar T lymphocytes

    PubMed Central

    Petterson, Terese; Månsson, Anne; Riesbeck, Kristian; Cardell, Lars O

    2011-01-01

    Nucleotide-binding and oligomerization domain (NOD) -like receptors (NLRs) and retinoic acid-inducible gene (RIG) -like receptors (RLRs) are recently discovered cytosolic pattern-recognition receptors sensing mainly bacterial components and viral RNA, respectively. Their importance in various cells and disorders is becoming better understood, but their role in human tonsil-derived T lymphocytes remains to be elucidated. In this study, we evaluated expression and functional relevance of NLRs and RLRs in human tonsillar CD3+ T lymphocytes. Immunohistochemistry, real-time RT-PCR and flow cytometry revealed expression of NOD1, NOD2, NALP1, NALP3, NAIP, IPAF, RIG-1, MDA-5 and LGP-2 at mRNA and protein levels. Because of the limited number of ligands (iE-DAP, MDP, Alum, Poly(I:C)/LyoVec), functional evaluation was restricted to NOD1, NOD2, NALP3 and RIG-1/MDA-5, respectively. Stimulation with the agonists alone was not enough to induce activation but upon triggering via CD3 and CD28, a profound induction of proliferation was seen in purified CD3+ T cells. However, the proliferative response was not further enhanced by the cognate ligands. Nonetheless, in tonsillar mononuclear cells iE-DAP, MDP and Poly(I:C)/LyoVec were found to augment the CD3/CD28-induced proliferation of tonsillar mononuclear cells. Also, iE-DAP and MDP were found to promote secretion of interleukins 2 and 10 as well as to up-regulate CD69. This study demonstrates for the first time a broad range of NLRs and RLRs in human tonsillar T cells and that NOD1, NOD2 and RIG-1/MDA-5 act synergistically with ?CD3 and ?CD28 to induce proliferation of human T cells. Hence, these results suggest that these receptors have a role in T-cell activation. PMID:21342182

  9. Nucleotide-binding and oligomerization domain-like receptors and retinoic acid inducible gene-like receptors in human tonsillar T lymphocytes.

    PubMed

    Petterson, Terese; Månsson, Anne; Riesbeck, Kristian; Cardell, Lars O

    2011-05-01

    Nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) and retinoic acid-inducible gene (RIG)-like receptors (RLRs) are recently discovered cytosolic pattern-recognition receptors sensing mainly bacterial components and viral RNA, respectively. Their importance in various cells and disorders is becoming better understood, but their role in human tonsil-derived T lymphocytes remains to be elucidated. In this study, we evaluated expression and functional relevance of NLRs and RLRs in human tonsillar CD3(+) T lymphocytes. Immunohistochemistry, real-time RT-PCR and flow cytometry revealed expression of NOD1, NOD2, NALP1, NALP3, NAIP, IPAF, RIG-1, MDA-5 and LGP-2 at mRNA and protein levels. Because of the limited number of ligands (iE-DAP, MDP, Alum, Poly(I:C)/LyoVec), functional evaluation was restricted to NOD1, NOD2, NALP3 and RIG-1/MDA-5, respectively. Stimulation with the agonists alone was not enough to induce activation but upon triggering via CD3 and CD28, a profound induction of proliferation was seen in purified CD3(+) T cells. However, the proliferative response was not further enhanced by the cognate ligands. Nonetheless, in tonsillar mononuclear cells iE-DAP, MDP and Poly(I:C)/LyoVec were found to augment the CD3/CD28-induced proliferation of tonsillar mononuclear cells. Also, iE-DAP and MDP were found to promote secretion of interleukins 2 and 10 as well as to up-regulate CD69. This study demonstrates for the first time a broad range of NLRs and RLRs in human tonsillar T cells and that NOD1, NOD2 and RIG-1/MDA-5 act synergistically with ?CD3 and ?CD28 to induce proliferation of human T cells. Hence, these results suggest that these receptors have a role in T-cell activation. PMID:21342182

  10. 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

  11. 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

  12. From germinal matrix to cerebellar haemorrhage.

    PubMed

    Fumagalli, Monica; Bassi, Laura; Sirgiovanni, Ida; Mosca, Fabio; Sannia, Andrea; Ramenghi, Luca A

    2013-08-23

    Abstract For many years cerebellar development after preterm birth has been poorly investigated and has been studied without taking germinal matrix-intraventricular haemorrhage into account. Advanced neuroimaging techniques like magnetic resonance imaging, as well as the use of various acoustic windows (mastoid fontanelle, occipital foramen) have allowed for in vivo diagnosis of acquired focal haemorrhagic lesions in the cerebellum of very preterm babies. The vulnerability of the cerebellum also seems to be related to specific gestational ages, i.e., between 23 and 27 weeks, when rapid growth in cerebellar volume occurs and at a much faster rate than mean brain volume increase. In this paper, the contribution of the cerebellum in long-term motor cognitive, learning and behavioural functions, including psychiatric ones, is discussed. PMID:23968333

  13. Cerebellar symptoms heralding bilirubin encephalopathy in Crigler-Najjar syndrome.

    PubMed

    Tabarki, Brahim; Khalifa, Monia; Yacoub, Moncef; Tlili, Kalthoum; Essoussi, Ahmed S

    2002-09-01

    Children with Crigler-Najjar syndrome type I are at increased risk for neurologic deficits. Cerebellar symptoms are not prominent and appear in adolescent or adult patients with this syndrome. We report a 2-year-old female with Crigler-Najjar syndrome type I who presented severe cerebellar symptoms revealing bilirubin encephalopathy. The patient improved slowly with the duration of phototherapy. Cerebellar symptoms can be the initial manifestation of kernicterus in children with Crigler-Najjar syndrome type I. PMID:12393137

  14. Cerebellar symptoms heralding bilirubin encephalopathy in crigler-najjar syndrome

    Microsoft Academic Search

    Brahim Tabarki; Monia Khalifa; Moncef Yacoub; Kalthoum Tlili; Ahmed S Essoussi

    2002-01-01

    Children with Crigler-Najjar syndrome type I are at increased risk for neurologic deficits. Cerebellar symptoms are not prominent and appear in adolescent or adult patients with this syndrome. We report a 2-year-old female with Crigler-Najjar syndrome type I who presented severe cerebellar symptoms revealing bilirubin encephalopathy. The patient improved slowly with the duration of phototherapy. Cerebellar symptoms can be the

  15. Cerebellar imaging – an important signpost in paediatric neurology

    Microsoft Academic Search

    Eugen Boltshauser

    2001-01-01

    Cerebellar function has traditionally been viewed as limited to the control of voluntary movement. There is increasing clinical\\u000a and experimental evidence that the cerebellum is involved in nonmotor behaviours and cognitive operations. In acquired and\\u000a congenital cerebellar lesions such deficits can be demonstrated by appropriate testing. These nonmotor functions explain,\\u000a at least in part, why many children with congenital cerebellar

  16. Coordinate systems for conformal cerebellar flat maps

    Microsoft Academic Search

    Monica K. Hurdal; Ken Stephenson; Phil Bowers; De Witt Sumners; David A. Rottenberg

    2000-01-01

    Methods Quasi-conformal flat maps of the human cerebellum (1,4) were created from a high-resolution Tl-weighted MRI volume (5). A topologically correct surface was produced from a cerebellar volume defined by a plane parallel to the posterior commisure-obex line and orthogonal to a plane passing through the vermal midline. Our quasi-conformal flattening procedure (2,3) was applied to this surface to produce

  17. 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

  18. 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

  19. APOLLO 11: Lunar Module Separates for descent

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Separation of the Lunar module for descent to the Lunar surface From the film documentary 'APOLLO 11:'The eagle Has Landed'', part of a documentary series on the APOLLO missions made in the early '70's and narrated by Burgess Meredith. APOLLO 11: First manned lunar landing and return to Earth with Neil A. Armstrong, Michael Collins, and Edwin E. Aldrin. Landed in the Sea of Tranquilityon July 20, 1969; deployed TV camera and EASEP experiments, performed lunar surface EVA, returned lunar soil samples. Mission Duration 195 hrs 18 min 35sec

  20. A steepest descents method for reentry optimization

    NASA Technical Reports Server (NTRS)

    Andrus, J. F.; Suchomel, C. F.

    1975-01-01

    A steepest descents optimization program is applied to the problem of a lifting vehicle entering the earth's atmosphere. The program employs penalty functions representing terminal conditions and inflight inequality constraints. During each iteration, it reduces a single performance measure which is the sum of the performance index and the penalty functions. Therefore, only one set of adjoint equations must be integrated per iteration. Values of weight factors, multiplying the penalty functions, are automatically adjusted before each iteration in order that the penalty functions will approach acceptable values. This method is shown to be a form of the classical Lagrange multiplier methods.

  1. System for Estimating Horizontal Velocity During Descent

    NASA Technical Reports Server (NTRS)

    Johnson, Andrew; Cheng, Yang; Wilson, Reg; Goguen, Jay; Martin, Alejandro San; Leger, Chris; Matthies, Larry

    2007-01-01

    The descent image motion estimation system (DIMES) is a system of hardware and software, designed for original use in estimating the horizontal velocity of a spacecraft descending toward a landing on Mars. The estimated horizontal velocity is used in generating rocket-firing commands to reduce the horizontal velocity as part of an overall control scheme to minimize the landing impact. DIMES can also be used for estimating the horizontal velocity of a remotely controlled or autonomous aircraft for purposes of navigation and control.

  2. 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.

  3. Krylov Subspace Descent for Deep Learning

    E-print Network

    Vinyals, Oriol

    2011-01-01

    In this paper, we propose a second order optimization method to learn models where both the dimensionality of the parameter space and the number of training samples is high. In our method, we construct on each iteration a Krylov subspace formed by the gradient and an approximation to the Hessian matrix, and then use a subset of the training data samples to optimize over this subspace. As with the Hessian Free (HF) method of [7], the Hessian matrix is never explicitly constructed, and is computed using a subset of data. In practice, as in HF, we typically use a positive definite substitute for the Hessian matrix such as the Gauss-Newton matrix. We investigate the effectiveness of our proposed method on deep neural networks, and compare its performance to widely used methods such as stochastic gradient descent, conjugate gradient descent and L-BFGS, and also to HF. Our method leads to faster convergence than either L-BFGS or HF, and generally performs better than either of them in cross-validation accuracy. It ...

  4. Cerebellar strokes: a clinical outcome review of 79 cases

    PubMed Central

    Ng, Zhi Xu; Yang, Wei Ren Eugene; Seet, Edwin; Koh, Kiok Miang; Teo, Ke Jia; Low, Shiong Wen; Chou, Ning; Yeo, Tseng Tsai; Venketasubramanian, N

    2015-01-01

    INTRODUCTION Cerebellar infarcts and haemorrhages are relatively uncommon, accounting for less than 10% of all strokes. The objective of the present study was to quantify and compare the outcomes of patients with cerebellar infarct and those of patients with cerebellar haemorrhage, as well as to identify the risk factors that predict poor outcome in patients with cerebellar stroke. METHODS We retrospectively reviewed the medical records of consecutive patients admitted to National University Hospital, Singapore, between 2004 and 2006, within one week of cerebellar stroke onset. Baseline data included demographics, concomitant comorbidities, and the presence or absence of brainstem compression and hydrocephalus (on computed tomography or magnetic resonance imaging). The Glasgow Outcome Scale and modified Rankin Score were used to assess outcome at discharge and at six months after discharge. RESULTS A total of 79 patients with cerebellar stroke were admitted during the study period. Of these 79 patients, 17.7% died and 31.6% had poor outcomes at six months after discharge. Patients with cerebellar haemorrhage were found to be more likely to have poor outcomes as compared to patients with cerebellar infarct, both at discharge (odds ratio [OR] 4.3, 95% confidence interval [CI] 1.3–14.1) and at six months after discharge (OR 5.2, 95% CI 1.6–17.2). When compared to small lesions (< 5 cm3), lesions > 20 cm3 were significantly associated with poorer outcomes and the development of hydrocephalus and brainstem compression. CONCLUSION Cerebellar strokes are a significant cause of morbidity and mortality. The outcomes of patients with cerebellar haemorrhage are more likely to be worse than those of patients with cerebellar infarct. PMID:25820846

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

    NASA Technical Reports Server (NTRS)

    Steltzner, Adam D.; San Martin, A. Miguel; Rivellini, Tomasso P.; Chen, Allen

    2013-01-01

    The Mars Science Laboratory project recently places the Curiosity rove on the surface of Mars. With the success of the landing system, the performance envelope of entry, descent and landing capabilities has been extended over the previous state of the art. This paper will present an overview to the MSL entry, descent and landing system design and preliminary flight performance results.

  6. Coefficient of Kinetic Friction of Snow Skis during Turning Descents

    NASA Astrophysics Data System (ADS)

    Sahashi, Toshio; Ichino, Shoji

    1998-02-01

    On a snow plane, descents were performed by snow plows, stem turns, parallel turns and wedelns. The descents were photographed in sequence and these were used to draw the loci of the skis. Coefficients of kinetic friction between the skis and the snow during the turns were obtained from the loci; their values were between 0.01 and 0.3.

  7. Humor and laughter in patients with cerebellar degeneration.

    PubMed

    Frank, B; Propson, B; Göricke, S; Jacobi, H; Wild, B; Timmann, D

    2012-06-01

    Humor is a complex behavior which includes cognitive, affective and motor responses. Based on observations of affective changes in patients with cerebellar lesions, the cerebellum may support cerebral and brainstem areas involved in understanding and appreciation of humorous stimuli and expression of laughter. The aim of the present study was to examine if humor appreciation, perception of humorous stimuli, and the succeeding facial reaction differ between patients with cerebellar degeneration and healthy controls. Twenty-three adults with pure cerebellar degeneration were compared with 23 age-, gender-, and education-matched healthy control subjects. No significant difference in humor appreciation and perception of humorous stimuli could be found between groups using the 3 Witz-Dimensionen Test, a validated test asking for funniness and aversiveness of jokes and cartoons. Furthermore, while observing jokes, humorous cartoons, and video sketches, facial expressions of subjects were videotaped and afterwards analysed using the Facial Action Coding System. Using depression as a covariate, the number, and to a lesser degree, the duration of facial expressions during laughter were reduced in cerebellar patients compared to healthy controls. In sum, appreciation of humor appears to be largely preserved in patients with chronic cerebellar degeneration. Cerebellar circuits may contribute to the expression of laughter. Findings add to the literature that non-motor disorders in patients with chronic cerebellar disease are generally mild, but do not exclude that more marked disorders may show up in acute cerebellar disease and/or in more specific tests of humor appreciation. PMID:22012411

  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. CASE REPORT Open Access Autosomal recessive cerebellar ataxia caused

    E-print Network

    Paris-Sud XI, Université de

    (ARCA) include Friedreich ataxia, ataxia telangiectasia and oculomotor apraxia type 1 and 2 [1CASE 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

  10. 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…

  11. Learning-induced plasticity in deep cerebellar nucleus.

    PubMed

    Ohyama, Tatsuya; Nores, William L; Medina, Javier F; Riusech, Frank A; Mauk, Michael D

    2006-12-01

    Evidence that cerebellar learning involves more than one site of plasticity comes from, in part, pavlovian eyelid conditioning, where disconnecting the cerebellar cortex abolishes one component of learning, response timing, but spares the expression of abnormally timed short-latency responses (SLRs). Here, we provide evidence that SLRs unmasked by cerebellar cortex lesions are mediated by an associative form of learning-induced plasticity in the anterior interpositus nucleus (AIN) of the cerebellum. We used pharmacological inactivation and/or electrical microstimulation of various sites afferent and efferent to the AIN to systematically eliminate alternative candidate sites of plasticity upstream or downstream from this structure. Collectively, the results suggest that cerebellar learning is mediated in part by plasticity in target nuclei downstream of the cerebellar cortex. These data demonstrate an instance in which an aspect of associative learning, SLRs, can be used as an index of plasticity at a specific site in the brain. PMID:17151268

  12. Cerebellar control of gait and interlimb coordination.

    PubMed

    Vinueza Veloz, María Fernanda; Zhou, Kuikui; Bosman, Laurens W J; Potters, Jan-Willem; Negrello, Mario; Seepers, Robert M; Strydis, Christos; Koekkoek, Sebastiaan K E; De Zeeuw, Chris I

    2014-08-20

    Synaptic and intrinsic processing in Purkinje cells, interneurons and granule cells of the cerebellar cortex have been shown to underlie various relatively simple, single-joint, reflex types of motor learning, including eyeblink conditioning and adaptation of the vestibulo-ocular reflex. However, to what extent these processes contribute to more complex, multi-joint motor behaviors, such as locomotion performance and adaptation during obstacle crossing, is not well understood. Here, we investigated these functions using the Erasmus Ladder in cell-specific mouse mutant lines that suffer from impaired Purkinje cell output (Pcd), Purkinje cell potentiation (L7-Pp2b), molecular layer interneuron output (L7-??2), and granule cell output (?6-Cacna1a). We found that locomotion performance was severely impaired with small steps and long step times in Pcd and L7-Pp2b mice, whereas it was mildly altered in L7-??2 and not significantly affected in ?6-Cacna1a mice. Locomotion adaptation triggered by pairing obstacle appearances with preceding tones at fixed time intervals was impaired in all four mouse lines, in that they all showed inaccurate and inconsistent adaptive walking patterns. Furthermore, all mutants exhibited altered front-hind and left-right interlimb coordination during both performance and adaptation, and inconsistent walking stepping patterns while crossing obstacles. Instead, motivation and avoidance behavior were not compromised in any of the mutants during the Erasmus Ladder task. Our findings indicate that cell type-specific abnormalities in cerebellar microcircuitry can translate into pronounced impairments in locomotion performance and adaptation as well as interlimb coordination, highlighting the general role of the cerebellar cortex in spatiotemporal control of complex multi-joint movements. PMID:25139623

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. Planetary entry, descent, and landing technologies

    NASA Astrophysics Data System (ADS)

    Pichkhadze, K.; Vorontsov, V.; Polyakov, A.; Ivankov, A.; Taalas, P.; Pellinen, R.; Harri, A.-M.; Linkin, V.

    2003-04-01

    Martian meteorological lander (MML) is intended for landing on the Martian surface in order to monitor the atmosphere at landing point for one Martian year. MMLs shall become the basic elements of a global network of meteorological mini-landers, observing the dynamics of changes of the atmospheric parameters on the Red Planet. The MML main scientific tasks are as follows: (1) Study of vertical structure of the Martian atmosphere throughout the MML descent; (2) On-surface meteorological observations for one Martian year. One of the essential factors influencing the lander's design is its entry, descent, and landing (EDL) sequence. During Phase A of the MML development, five different options for the lander's design were carefully analyzed. All of these options ensure the accomplishment of the above-mentioned scientific tasks with high effectiveness. CONCEPT A (conventional approach): Two lander options (with a parachute system + airbag and an inflatable airbrake + airbag) were analyzed. They are similar in terms of fulfilling braking phases and completely analogous in landing by means of airbags. CONCEPT B (innovative approach): Three lander options were analyzed. The distinguishing feature is the presence of inflatable braking units (IBU) in their configurations. SELECTED OPTION (innovative approach): Incorporating a unique design approach and modern technologies, the selected option of the lander represents a combination of the options analyzed in the framework of Concept B study. Currently, the selected lander option undergoes systems testing (Phase D1). Several MMLs can be delivered to Mars in frameworks of various missions as primary or piggybacking payload: (1) USA-led "Mars Scout" (2007); (2) France-led "NetLander" (2007/2009); (3) Russia-led "Mars-Deimos-Phobos sample return" (2007); (4) Independent mission (currently under preliminary study); etc.

  18. 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

  19. Single Photon Emission Computed Tomography (SPECT) in Cerebellar Disease: Cerebello-Cerebral Diaschisis

    Microsoft Academic Search

    M. I. Botez; Jean Léveillé; Raymond Lambert; Thérèse Botez

    1991-01-01

    Single photon emission computed tomography assessments were conducted in normal controls (n = 25), patients with unilateral cerebellar infarctions (n = 4), patients with olivopontocerebellar atrophy (OPCA; n = 15) and patients with Friedreich’s ataxia (FA; n = 6). In subjects with unilateral cerebellar infarctions, crossed cerebellar-cortical diaschisis was observed: reduced cerebellar hexamethylpropyleneamine oxime (HMPAO) uptake was invariably accompanied by

  20. Loss of Smarc proteins impairs cerebellar development.

    PubMed

    Moreno, Natalia; Schmidt, Christin; Ahlfeld, Julia; Pöschl, Julia; Dittmar, Stefanie; Pfister, Stefan M; Kool, Marcel; Kerl, Kornelius; Schüller, Ulrich

    2014-10-01

    SMARCA4 (BRG1) and SMARCB1 (INI1) are tumor suppressor genes that are crucially involved in the formation of malignant rhabdoid tumors, such as atypical teratoid/rhabdoid tumor (AT/RT). AT/RTs typically affect infants and occur at various sites of the CNS with a particular frequency in the cerebellum. Here, granule neurons and their progenitors represent the most abundant cell type and are known to give rise to a subset of medulloblastoma, a histologically similar embryonal brain tumor. To test how Smarc proteins influence the development of granule neurons and whether this population may serve as cellular origin for AT/RTs, we specifically deleted Smarca4 and Smarcb1 in cerebellar granule cell precursors. Respective mutant mice displayed severe ataxia and motor coordination deficits, but did not develop any tumors. In fact, they suffered from a severely hypoplastic cerebellum due to a significant inhibition of granule neuron precursor proliferation. Molecularly, this was accompanied by an enhanced activity of Wnt/?-catenin signaling that, by itself, is known to cause a nearly identical phenotype. We further used an hGFAP-cre allele, which deleted Smarcb1 much earlier and in a wider neural precursor population, but we still did not detect any tumor formation in the CNS. In summary, our results emphasize cell-type-dependent roles of Smarc proteins and argue against cerebellar granule cells and other progeny of hGFAP-positive neural precursors as the cellular origin for AT/RTs. PMID:25274825

  1. Up-regulation of CC chemokine receptor 6 on tonsillar T cells and its induction by in vitro stimulation with ?-streptococci in patients with pustulosis palmaris et plantaris

    PubMed Central

    Yoshizaki, T; Bandoh, N; Ueda, S; Nozawa, H; Goto, T; Kishibe, K; Takahara, M; Harabuchi, Y

    2009-01-01

    Pustulosis palmaris et plantaris (PPP) is a tonsil-related disease; tonsillectomy is somewhat effective in treating the condition. However, the aetiological association between the tonsils and PPP has not yet been elucidated fully. Recently, some chemokines and chemokine receptors, including CC chemokine receptor (CCR) 4, CCR6 and CX chemokine receptor (CXCR) 3, have been reported to play important roles in the development of psoriasis, a disease related closely to PPP. In this study, we found that CCR6 expression on both tonsillar and peripheral blood T cells was up-regulated more intensively in PPP patients than in non-PPP patients (P < 0·001 for both), but CCR4 and CXCR3 expressions were not. In vitro stimulation with ?-streptococcal antigen enhanced CCR6 expression significantly on tonsillar T cells in PPP patients (P < 0·05), but this was not observed in non-PPP patients. The chemotactic response of tonsillar T cells to the CCR6 ligand CC chemokine ligand (CCL) 20 was significantly higher in PPP patients than in non-PPP patients (P < 0·05). The percentage of CCR6-positive peripheral blood T cells decreased after tonsillectomy in PPP patients (P < 0·01); this decrease correlated with an improvement of skin lesions (P < 0·05, r = ?0·63). The numbers of CCR6-positive cells and the expression of CCL20 were increased significantly in pathological lesions compared with non-pathological lesions in PPP skin (P < 0·01, P < 0·05 respectively). These results suggest that a novel immune response to ?-streptococci may enhance CCR6 expression on T cells in tonsils and that CCR6-positive T cells may move to peripheral blood circulation, resulting in recruitment to target skin lesions expressing CCL20 in PPP patients. This may be one of the key roles in pathogenesis of the tonsil-related disease PPP. PMID:19659772

  2. COUNTING DESCENTS, RISES, AND LEVELS, WITH PRESCRIBED FIRST ELEMENT, IN WORDS

    E-print Network

    Kitaev, Sergey

    COUNTING DESCENTS, RISES, AND LEVELS, WITH PRESCRIBED FIRST ELEMENT, IN WORDS Sergey Kitaev1 the distribution of descents, levels, and rises according to whether the first letter of the descent, rise 0654060 1 #12;2 COUNTING DESCENTS, RISES, AND LEVELS, WITH PRESCRIBED FIRST ELEMENT, IN WORDS Subsequently

  3. 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

  4. 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

  5. Differentiating cerebellar and brainstem lesions with ocular vestibular-evoked myogenic potential test

    Microsoft Academic Search

    Chia-Hung Su; Yi-Ho Young

    2011-01-01

    This study applied both ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) tests in patients with\\u000a cerebellar disorders to determine whether VEMP test can differentiate between cerebellar and brainstem lesions. A total of\\u000a 12 patients with cerebellar disorder, including extended cerebellar lesion (involving the brainstem) in 8 and localized cerebellar\\u000a lesion (excluding the brainstem) in 4, were enrolled in

  6. 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

  7. Ocular tilt reaction due to a cerebellar hemorrhage.

    PubMed

    Tsuda, Hiromasa; Tanaka, Kozue

    2014-01-01

    A 78-year-old man with essential hypertension abruptly developed complete ocular tilt reaction (OTR) which consisted of concomitant skew deviation with left hypertropia, extorsion of the right eye and intorsion of the left, and rightward head tilt. Cranial computed tomography demonstrated a localized cerebellar hemorrhage involving the left nodulus. The patient became asymptomatic within two weeks. This is a first reported case of complete OTR due to a cerebellar hemorrhage. Concomitant skew deviation is a common symptom of cerebellar lesions. Moreover, unilateral damage to the utricular pathway due to involvement of the left nodulus might cause rightward conjugate ocular torsion and rightward head tilt. PMID:25274240

  8. A Coordinate Descent Algorithm for Learning Compact Ranking Functions

    E-print Network

    Singer, Yoram

    A Coordinate Descent Algorithm for Learning Compact Ranking Functions Mark Stevens stevensm@google.com Samy Bengio bengio@google.com Yoram Singer singer@google.com Abstract Algorithms for learning to rank

  9. 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...

  10. 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.

  11. 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 ...

  12. 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.

  13. TRAJECTORIES OF DESCENT 1. Introduction. The intuitive notion ...

    E-print Network

    2012-12-21

    study slight relaxations of two influential notions of steepest descent curves — curves of maximal slope and .... motivated by the desire to make the basic ideas and the techniques as clear as possible ... Section 2 is a self-contained treatment

  14. Germline recessive mutations in PI4KA are associated with perisylvian polymicrogyria, cerebellar hypoplasia and arthrogryposis.

    PubMed

    Pagnamenta, Alistair T; Howard, Malcolm F; Wisniewski, Eva; Popitsch, Niko; Knight, Samantha J L; Keays, David A; Quaghebeur, Gerardine; Cox, Helen; Cox, Phillip; Balla, Tamas; Taylor, Jenny C; Kini, Usha

    2015-07-01

    Polymicrogyria (PMG) is a structural brain abnormality involving the cerebral cortex that results from impaired neuronal migration and although several genes have been implicated, many cases remain unsolved. In this study, exome sequencing in a family where three fetuses had all been diagnosed with PMG and cerebellar hypoplasia allowed us to identify regions of the genome for which both chromosomes were shared identical-by-descent, reducing the search space for causative variants to 8.6% of the genome. In these regions, the only plausibly pathogenic mutations were compound heterozygous variants in PI4KA, which Sanger sequencing confirmed segregated consistent with autosomal recessive inheritance. The paternally transmitted variant predicted a premature stop mutation (c.2386C>T; p.R796X), whereas the maternally transmitted variant predicted a missense substitution (c.5560G>A; p.D1854N) at a conserved residue within the catalytic domain. Functional studies using expressed wild-type or mutant PI4KA enzyme confirmed the importance of p.D1854 for kinase activity. Our results emphasize the importance of phosphoinositide signalling in early brain development. PMID:25855803

  15. Germline recessive mutations in PI4KA are associated with perisylvian polymicrogyria, cerebellar hypoplasia and arthrogryposis

    PubMed Central

    Pagnamenta, Alistair T.; Howard, Malcolm F.; Wisniewski, Eva; Popitsch, Niko; Knight, Samantha J.L.; Keays, David A.; Quaghebeur, Gerardine; Cox, Helen; Cox, Phillip; Balla, Tamas; Taylor, Jenny C.; Kini, Usha

    2015-01-01

    Polymicrogyria (PMG) is a structural brain abnormality involving the cerebral cortex that results from impaired neuronal migration and although several genes have been implicated, many cases remain unsolved. In this study, exome sequencing in a family where three fetuses had all been diagnosed with PMG and cerebellar hypoplasia allowed us to identify regions of the genome for which both chromosomes were shared identical-by-descent, reducing the search space for causative variants to 8.6% of the genome. In these regions, the only plausibly pathogenic mutations were compound heterozygous variants in PI4KA, which Sanger sequencing confirmed segregated consistent with autosomal recessive inheritance. The paternally transmitted variant predicted a premature stop mutation (c.2386C>T; p.R796X), whereas the maternally transmitted variant predicted a missense substitution (c.5560G>A; p.D1854N) at a conserved residue within the catalytic domain. Functional studies using expressed wild-type or mutant PI4KA enzyme confirmed the importance of p.D1854 for kinase activity. Our results emphasize the importance of phosphoinositide signalling in early brain development. PMID:25855803

  16. An accelerated random coordinate descent algorithm for compressed sensing

    NASA Astrophysics Data System (ADS)

    Chen, Dongfang; Zhang, Ningtao

    2011-10-01

    This paper introduces a new accelerated random coordinate descent algorithm for solving problems in the field of compressive sensing, and more generally, in the field of signal and image reconstruction from indirect or incomplete measurements. This algorithm is inspired by recent progress in convex optimization development of coordinate descent. Our method is very efficient for solving compressive sensing data recovery problems. Numerical experiments show the performance of our algorithm to solve high-dimensional optimization problems.

  17. Testicular descent: INSL3, testosterone, genes and the intrauterine milieu

    Microsoft Academic Search

    Katharina M. Main; Jorma Toppari; Niels E. Skakkebæk; Katrine Bay

    2011-01-01

    Complete testicular descent is a sign of, and a prerequisite for, normal testicular function in adult life. The process of testis descent is dependent on gubernacular growth and reorganization, which is regulated by the Leydig cell hormones insulin-like peptide 3 (INSL3) and testosterone. Investigation of the role of INSL3 and its receptor, relaxin-family peptide receptor 2 (RXFP2), has contributed substantially

  18. The Descent Set and Connectivity Set of a Permutation 1

    E-print Network

    )} = #(S) #{w # S n : S # D(w)} = n! #(S) . Proof. The result for D(w) is well­known, e.g., [6, Prop. 1The Descent Set and Connectivity Set of a Permutation 1 Richard P. Stanley 2 Department August 2005 Abstract The descent set D(w) of a permutation w of 1, 2, . . . , n is a standard and well

  19. 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.

  20. Chronic THC intake modifies fundamental cerebellar functions.

    PubMed

    Stella, Nephi

    2013-08-01

    Delta9-tetrahydrocannabinol (THC), the principal bioactive component in the Cannabis plant, is truly a captivating drug. Acute and chronic THC intake produces a spectrum of biological effects ranging from transient psychotropic effects to prolonged medicinal benefits, many of which have been fostered for centuries by our society. In the July 2013 issue of the JCI, Cutando et al. combined mouse genetics with classic mouse behavioral analysis to deepen our understanding of the physiological consequence of subchronic THC intake on eyeblink reflexes, a fundamental neuronal adaptive response, revealing that this regimen leads to downregulation of the cannabinoid CB1 receptor (referred to as CB1 in the Cutando et al. article) in cerebellar stress fibers and the activation of microglia, raising provocative new questions about the safety profile of regimented THC intake. PMID:23863631

  1. Hereditary Cerebellar Ataxias: A Korean Perspective

    PubMed Central

    Kim, Ji Sun; Cho, Jin Whan

    2015-01-01

    Hereditary ataxia is a heterogeneous disorder characterized by progressive ataxia combined with/without peripheral neuropathy, extrapyramidal symptoms, pyramidal symptoms, seizure, and multiple systematic involvements. More than 35 autosomal dominant cerebellar ataxias have been designated as spinocerebellar ataxia, and there are 55 recessive ataxias that have not been named systematically. Conducting genetic sequencing to confirm a diagnosis is difficult due to the large amount of subtypes with phenotypic overlap. The prevalence of hereditary ataxia can vary among countries, and estimations of prevalence and subtype frequencies are necessary for planning a diagnostic strategy in a specific population. This review covers the various hereditary ataxias reported in the Korean population with a focus on the prevalence and subtype frequencies as the clinical characteristics of the various subtypes.

  2. Asterixis as a Presentation of Cerebellar Ischemic Stroke

    PubMed Central

    Siniscalchi, Antonio; Gallelli, Luca; Di Benedetto, Olindo; De Sarro, Giovambattista

    2012-01-01

    Asterixis is not yet considered a common neurological sign of cerebellum infarction, and the pathogenic mechanism for asterixis remains elusive. We report a 58-year-old male with moderate hypertension who presented to our emergency department for acute headache in both cervical and occipital regions of the left side. About 2 hours later the patient developed ipsilateral asterixis in the upper left limb; 3 days later the asterixis disappeared. Magnetic resonance imaging of the brain disclosed cerebellar infarctions at the left superior cerebellar artery. In conclusion, we observed that a transitory asterixis associated with ipsilateral headache can be an initial clinical manifestation of ipsilateral cerebellar infarctions in the superior cerebellar artery area. PMID:23359270

  3. 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 ...

  4. A New Functional Role for Cerebellar Long Term Depression

    E-print Network

    De Schutter, Erik

    , 1984). Purkinje cells receive two types of excitatory inputs: climbing fibers (CF) from the inferior olive and parallel fibers (PF) from cerebellar granule cells. Each Purkinje cell receives only one CF

  5. 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

  6. Memory impairment following right cerebellar infarction: a case study.

    PubMed

    Nakamoto, Fumiko Kusunoki; Tsutsumiuchi, Michiko; Maeda, Meiko Hashimoto; Uesaka, Yoshikazu; Takeda, Katsuhiko

    2015-10-01

    We reported a patient with a right cerebellar infarction who showed anterograde amnesia. Cognitive dysfunction caused by cerebellar lesions was called cerebellar cognitive affective syndrome, and deactivation of the contralateral prefrontal cortex function due to disconnections of cerebello-cerebral fiber tracts have been hypothesized as mechanism underlying the syndrome. The episodic memory impairment, however, could not be supported by the same mechanism because the prefrontal lesions cannot cause amnesia syndrome. The feature of the impairment of our patient was similar to that of diencephalic amnesia, and a single photon emission computed tomography study showed a relative hypoperfusion in the right cerebellar hemisphere and left anterior thalamus. We considered that the memory deficit was caused by the dysfunction of the thalamus, which is a relay center of the cerebello-cerebral connectivity network. PMID:25350282

  7. 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

  8. Hypocupremia: A Possible Association with Late Cortical Cerebellar Atrophy

    PubMed Central

    Mittal, Shivam Om; Machado, Duarte G.

    2014-01-01

    Background We report a patient, diagnosed with late cortical cerebellar atrophy, who had persistent low serum copper levels. Case report A 48-year-old male developed progressive difficulty with balance, frequent falls, and dysarthric speech, which worsened over a short time span. He had an extensive ataxia work-up, which was unremarkable except for persistent low serum copper levels despite adequate supplementation. Magnetic resonance imaging of the brain showed marked cerebellar atrophy. The patient experienced progressive worsening of symptoms, which did not improve with either oral or parenteral copper supplementation. Discussion To our knowledge, ours is the first case report of late cortical cerebellar atrophy in the setting of low serum copper levels. The current report should trigger further research in mechanisms leading to copper deficiency and its possible role in cerebellar disease. PMID:25247109

  9. Novel Approaches to Studying the Genetic Basis of Cerebellar Development

    PubMed Central

    Sajan, Samin A.; Waimey, Kathryn E.

    2010-01-01

    The list of genes that when mutated cause disruptions in cerebellar development is rapidly increasing. The study of both spontaneous and engineered mouse mutants has been essential to this progress, as it has revealed much of our current understanding of the developmental processes required to construct the mature cerebellum. Improvements in brain imaging, such as magnetic resonance imaging (MRI) and the emergence of better classification schemes for human cerebellar malformations, have recently led to the identification of a number of genes which cause human cerebellar disorders. In this review we argue that synergistic approaches combining classical molecular techniques, genomics, and mouse models of human malformations will be essential to fuel additional discoveries of cerebellar developmental genes and mechanisms. PMID:20387026

  10. Quantitative real-time polymerase chain reaction for detecting Mycoplasma hyosynoviae and Mycoplasma hyorhinis in pen-based oral, tonsillar, and nasal fluids

    PubMed Central

    Bower, Leslie; Erickson, Barbara Z.; Wang, Chong; Raymond, Matthew; Strait, Erin L.

    2015-01-01

    Mycoplasma (M.) hyorhinis and M. hyosynoviae are pathogens known to cause disease in pigs post-weaning. Due to their fastidious nature, there is increased need for culture-independent diagnostic platforms to detect these microorganisms. Therefore, this study was performed to develop and optimize quantitative real-time PCR (qPCR) assays to rapidly detect M. hyorhinis and M. hyosynoviae in pen-based oral fluids as well as nasal and tonsillar fluids as proxies for samples used in swine herd surveillance. Two methods of genomic DNA extraction, automated versus manual, were used to compare diagnostic test performance. A wean-to-finish longitudinal study was also carried out to demonstrate the reproducibility of using pen-based oral fluids. Overall, pen-based oral and tonsillar fluids were more likely to be positive for both types of bacteria whereas only M. hyorhinis was detected in nasal fluids. DNA extraction protocols were shown to significantly influence test result. Although the initial detection time somewhat differed, both organisms were repeatedly detected in the longitudinal study. Overall, this study evaluated two qPCR methods for rapid and specific detection of either mycoplasma. Results from the present investigation can serve as a foundation for future studies to determine the prevalence of the two microorganisms, environmental load, and effectiveness of veterinary interventions for infection control. PMID:25643803

  11. Agreement Rate of Rapid Urease Test, Conventional PCR, and Scorpion Real-Time PCR in Detecting Helicobacter Pylori from Tonsillar Samples of Patients with Chronic Tonsillitis

    PubMed Central

    Najafipour, Reza; Farivar, Taghi Naserpour; Pahlevan, Ali Akbar; Johari, Pouran; Safdarian, Farshid; Asefzadeh, Mina

    2012-01-01

    Background: Helicobacter pylori is capable of inducing systemic inflammatory reactions through immunological processes. There are several methods to identify the presence of H. pylori in clinical samples including rapid urease test (RUT), conventional polymerase chain reaction (PCR), and the Scorpion real-time PCR. Aim: The aim of the present study is to compare the agreement rate of these tests in identifying H. pylori in tonsillar biopsy specimens collected from patients with chronic tonsillitis. Materials and Methods: A total of 103 tonsil biopsy samples from patients with clinical signs of chronic tonsillitis were examined with RUT, PCR, and Scorpion real-time PCR. The degree of agreement between the three tests was later calculated. Results: There was a poor degree of agreement between RUT and PCR and also RUT and Scorpion real-time PCR (Kappa=0.269 and 0.249, respectively). In contrast with RUT, there was a strong degree of agreement between PCR and Scorpion real-time PCR (Kappa=0.970). Conclusion: The presence of a strong agreement between the Scorpion real-time PCR and PCR as well as its technical advantage over the conventional PCR assay, made the Scorpion real-time PCR an appropriate laboratory test to investigate the presence of H. pylori in tonsillar biopsy specimens in patients suffering from chronic tonsillitis. PMID:22754245

  12. Quantitative real-time polymerase chain reaction for detecting Mycoplasma hyosynoviae and Mycoplasma hyorhinis in pen-based oral, tonsillar, and nasal fluids.

    PubMed

    Gomes Neto, João Carlos; Bower, Leslie; Erickson, Barbara Z; Wang, Chong; Raymond, Matthew; Strait, Erin L

    2015-06-01

    Mycoplasma (M.) hyorhinis and M. hyosynoviae are pathogens known to cause disease in pigs post-weaning. Due to their fastidious nature, there is increased need for culture-independent diagnostic platforms to detect these microorganisms. Therefore, this study was performed to develop and optimize quantitative real-time PCR (qPCR) assays to rapidly detect M. hyorhinis and M. hyosynoviae in pen-based oral fluids as well as nasal and tonsillar fluids as proxies for samples used in swine herd surveillance. Two methods of genomic DNA extraction, automated versus manual, were used to compare diagnostic test performance. A wean-to-finish longitudinal study was also carried out to demonstrate the reproducibility of using pen-based oral fluids. Overall, pen-based oral and tonsillar fluids were more likely to be positive for both types of bacteria whereas only M. hyorhinis was detected in nasal fluids. DNA extraction protocols were shown to significantly influence test result. Although the initial detection time somewhat differed, both organisms were repeatedly detected in the longitudinal study. Overall, this study evaluated two qPCR methods for rapid and specific detection of either mycoplasma. Results from the present investigation can serve as a foundation for future studies to determine the prevalence of the two microorganisms, environmental load, and effectiveness of veterinary interventions for infection control. PMID:25643803

  13. Mitotic events in cerebellar granule progenitor cells that expand cerebellar surface area are critical for normal cerebellar cortical lamination in mice.

    PubMed

    Chang, Joshua C; Leung, Mark; Gokozan, Hamza Numan; Gygli, Patrick Edwin; Catacutan, Fay Patsy; Czeisler, Catherine; Otero, José Javier

    2015-03-01

    Late embryonic and postnatal cerebellar folial surface area expansion promotes cerebellar cortical cytoarchitectural lamination. We developed a streamlined sampling scheme to generate unbiased estimates of murine cerebellar surface area and volume using stereologic principles. We demonstrate that, during the proliferative phase of the external granular layer (EGL) and folial surface area expansion, EGL thickness does not change and thus is a topological proxy for progenitor self-renewal. The topological constraints indicate that, during proliferative phases, migration out of the EGL is balanced by self-renewal. Progenitor self-renewal must, therefore, include mitotic events yielding 2 cells in the same layer to increase surface area (? events) and mitotic events yielding 2 cells, with 1 cell in a superficial layer and 1 cell in a deeper layer (? events). As the cerebellum grows, therefore, ? events lie upstream of ? events. Using a mathematical model constrained by the measurements of volume and surface area, we could quantify intermitotic times for ? events on a per-cell basis in postnatal mouse cerebellum. Furthermore, we found that loss of CCNA2, which decreases EGL proliferation and secondarily induces cerebellar cortical dyslamination, shows preserved ?-type events. Thus, CCNA2-null cerebellar granule progenitor cells are capable of self-renewal of the EGL stem cell niche; this is concordant with prior findings of extensive apoptosis in CCNA2-null mice. Similar methodologies may provide another layer of depth to the interpretation of results from stereologic studies. PMID:25668568

  14. 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. PMID:25883666

  15. Interhemispheric Asymmetry of Corticomotor Excitability After Chronic Cerebellar Infarcts

    Microsoft Academic Search

    Suzete Nascimento Farias da Guarda; Leonardo G. Cohen; Marco da Cunha Pinho; Fábio Iuji Yamamoto; Paulo Eurípedes Marchiori; Milberto Scaff; Adriana Bastos Conforto

    2010-01-01

    Early after stroke, there is loss of intracortical facilitation (ICF) and increase in short-interval intracortical inhibition\\u000a (SICI) in the primary motor cortex (M1) contralateral to a cerebellar infarct. Our goal was to investigate intracortical M1\\u000a function in the chronic stage following cerebellar infarcts (>4 months). We measured resting motor threshold (rMT), SICI,\\u000a ICF, and ratios between motor-evoked potential amplitudes (MEP) and

  16. Impaired Motor Learning Performance in Cerebellar En2 Mutant Mice

    Microsoft Academic Search

    R. Gerlai; K. J. Millen; K. Herrup; K. Fabien; A. L. Joyner; J. Roder

    1996-01-01

    Mice homozygous for a null mutation in their En-2 gene exhibit cerebellar neuroanatomical alterations including absence and misplacements of specific fissures and size reduction. The present study investigated cerebellar function by comparing the behavior of age-matched homozygous and heterozygous En-2 mutant and wild-type mice. Motor function of the mutants was found normal in several situations. Habituation to novelty in the

  17. Altered cerebellar connectivity in Parkinson's patients ON and OFF L-DOPA medication

    PubMed Central

    Festini, Sara B.; Bernard, Jessica A.; Kwak, Youngbin; Peltier, Scott; Bohnen, Nicolaas I.; Müller, Martijn L. T. M.; Dayalu, Praveen; Seidler, Rachael D.

    2015-01-01

    Although nigrostriatal changes are most commonly affiliated with Parkinson's disease, the role of the cerebellum in Parkinson's has become increasingly apparent. The present study used lobule-based cerebellar resting state functional connectivity to (1) compare cerebellar-whole brain and cerebellar-cerebellar connectivity in Parkinson's patients both ON and OFF L-DOPA medication and controls, and to (2) relate variations in cerebellar connectivity to behavioral performance. Results indicated that, when contrasted to the control group, Parkinson's patients OFF medication had increased levels of cerebellar-whole brain and cerebellar-cerebellar connectivity, whereas Parkinson's patients ON medication had decreased levels of cerebellar-whole brain and cerebellar-cerebellar connectivity. Moreover, analyses relating levels of cerebellar connectivity to behavioral measures demonstrated that, within each group, increased levels of connectivity were most often associated with improved cognitive and motor performance, but there were several instances where increased connectivity was related to poorer performance. Overall, the present study found medication-variant cerebellar connectivity in Parkinson's patients, further demonstrating cerebellar changes associated with Parkinson's disease and the moderating effects of medication. PMID:25954184

  18. Relevance of the cerebellar hemispheres for executive functions.

    PubMed

    Karatekin, C; Lazareff, J A; Asarnow, R F

    2000-02-01

    The aim of the present study was to elucidate the role of the cerebellar hemispheres in executive functions. The findings are relevant because of the large number of children who survive cerebellar tumors. Neuropsychologic assessments of four patients (8-21 years of age) who had undergone neurosurgery for removal of tumors in the cerebellar hemispheres were conducted and compared with the assessments of six children who had been diagnosed with temporal lobe tumors or cysts. The executive functions were assessed using the Wisconsin Card Sorting Test. IQs were average in both groups. As expected, patients with cerebellar hemispheric lesions had impaired executive functions. In particular, they appeared to have difficulty generating and testing hypotheses regarding the matching rules on the Wisconsin Card Sorting Test. Patients with temporal lesions had a different pattern of deficits on this test. The findings are consistent with the theories that propose that the cerebellar hemispheres are involved in cognitive processes. The findings also demonstrate that subtle deficits in executive functions can be masked by a normal IQ in survivors of cerebellar tumors and highlight the need to design interventions targeted toward problem-solving skills. PMID:10738915

  19. Bilateral cerebellar dysplastic gangliocytomas (lhermitte duclos disease) with cerebellar ectopia and presyrinx cord changes. A case report.

    PubMed

    Puri, A S; Garg, A; Mishra, N K; Gaikwad, S B; Mehta, V S; Cirillo, S

    2007-01-31

    Lhermitte-Duclos disease (LDD) is a rare cerebellar lesion with features of both malformation and benign neoplasm. However, the fundamental nature of the entity, its pathogenesis, and the exact genetic alterations remain unknown. We describe a rare case of bilateral LDD with cerebellar ectopia and presyrinx spinal cord changes. Bilaterality of lesions should argue against a neoplastic origin and support a hamartomatous origin. PMID:24351297

  20. Descent from the Summit of 'Husband Hill'

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for Descent from the Summit of 'Husband Hill' (QTVR)

    In late November 2005 while descending 'Husband Hill,' NASA's Mars Exploration Rover Spirit took the most detailed panorama so far of the 'Inner Basin,' the rover's next target destination. Spirit acquired the 405 individual images that make up this 360-degree view of the surrounding terrain using five different filters on the panoramic camera. The rover took the images on Martian days, or sols, 672 to 677 (Nov. 23 to 28, 2005 -- the Thanksgiving holiday weekend).

    This image is an approximately true-color rendering using camera's 750-, 530-, and 430-nanometer filters. Seams between individual frames have been eliminated from the sky portion of the mosaic to better simulate the vista a person standing on Mars would see.

    'Home Plate,' a bright, semi-circular feature scientists hope to investigate, is harder to discern in this image than in earlier views taken from higher up the hill. Spirit acquired this more oblique view, known as the 'Seminole panorama,' from about halfway down the south flank of Husband Hill, 50 meters (164 feet) or so below the summit. Near the center of the panorama, on the horizon, are 'McCool Hill' and 'Ramon Hill,' named, like Husband Hill, in honor of the fallen astronauts of the space shuttle Columbia. Husband Hill is visible behind the rover, on the right and left sides of the panorama. An arc of rover tracks made while avoiding obstacles and getting into position to examine rock outcrops can be traced over a long distance by zooming in to explore the panorama in greater detail.

    Spirit is now significantly farther downhill toward the center of this panorama, en route to Home Plate and other enigmatic soils and outcrop rocks in the quest to uncover the history of Gusev Crater and the 'Columbia Hills.'

  1. Defective cerebellar control of cortical plasticity in writer's cramp.

    PubMed

    Hubsch, Cecile; Roze, Emmanuel; Popa, Traian; Russo, Margherita; Balachandran, Ammu; Pradeep, Salini; Mueller, Florian; Brochard, Vanessa; Quartarone, Angelo; Degos, Bertrand; Vidailhet, Marie; Kishore, Asha; Meunier, Sabine

    2013-07-01

    A large body of evidence points to a role of basal ganglia dysfunction in the pathophysiology of dystonia, but recent studies indicate that cerebellar dysfunction may also be involved. The cerebellum influences sensorimotor adaptation by modulating sensorimotor plasticity of the primary motor cortex. Motor cortex sensorimotor plasticity is maladaptive in patients with writer's cramp. Here we examined whether putative cerebellar dysfunction in dystonia is linked to these patients' maladaptive plasticity. To that end we compared the performances of patients and healthy control subjects in a reaching task involving a visuomotor conflict generated by imposing a random deviation (-40° to 40°) on the direction of movement of the mouse/cursor. Such a task is known to involve the cerebellum. We also compared, between patients and healthy control subjects, how the cerebellum modulates the extent and duration of an ongoing sensorimotor plasticity in the motor cortex. The cerebellar cortex was excited or inhibited by means of repeated transcranial magnetic stimulation before artificial sensorimotor plasticity was induced in the motor cortex by paired associative stimulation. Patients with writer's cramp were slower than the healthy control subjects to reach the target and, after having repeatedly adapted their trajectories to the deviations, they were less efficient than the healthy control subjects to perform reaching movement without imposed deviation. It was interpreted as impaired washing-out abilities. In healthy subjects, cerebellar cortex excitation prevented the paired associative stimulation to induce a sensorimotor plasticity in the primary motor cortex, whereas cerebellar cortex inhibition led the paired associative stimulation to be more efficient in inducing the plasticity. In patients with writer's cramp, cerebellar cortex excitation and inhibition were both ineffective in modulating sensorimotor plasticity. In patients with writer's cramp, but not in healthy subjects, behavioural parameters reflecting their capacity for adapting to the rotation and for washing-out of an earlier adaptation predicted the efficacy of inhibitory cerebellar conditioning to influence sensorimotor plasticity: the better the online adaptation, the smaller the influence of cerebellar inhibitory stimulation on motor cortex plasticity. Altered cerebellar encoding of incoming afferent volleys may result in decoupling the motor component from the afferent information flow, and also in maladjusted sensorimotor calibration. The loss of cerebellar control over sensorimotor plasticity might also lead to building up an incorrect motor program to specific adaptation tasks such as writing. PMID:23801734

  2. Cerebellar development in the absence of Gbx function in zebrafish.

    PubMed

    Su, Chen-Ying; Kemp, Hilary A; Moens, Cecilia B

    2014-02-01

    The midbrain-hindbrain boundary (MHB) is a well-known organizing center during vertebrate brain development. The MHB forms at the expression boundary of Otx2 and Gbx2, mutually repressive homeodomain transcription factors expressed in the midbrain/forebrain and anterior hindbrain, respectively. The genetic hierarchy of gene expression at the MHB is complex, involving multiple positive and negative feedback loops that result in the establishment of non-overlapping domains of Wnt1 and Fgf8 on either side of the boundary and the consequent specification of the cerebellum. The cerebellum derives from the dorsal part of the anterior-most hindbrain segment, rhombomere 1 (r1), which undergoes a distinctive morphogenesis to give rise to the cerebellar primordium within which the various cerebellar neuron types are specified. Previous studies in the mouse have shown that Gbx2 is essential for cerebellar development. Using zebrafish mutants we show here that in the zebrafish gbx1 and gbx2 are required redundantly for morphogenesis of the cerebellar primordium and subsequent cerebellar differentiation, but that this requirement is alleviated by knocking down Otx. Expression of fgf8, wnt1 and the entire MHB genetic program is progressively lost in gbx1-;gbx2- double mutants but is rescued by Otx knock-down. This rescue of the MHB genetic program depends on rescued Fgf signaling, however the rescue of cerebellar primordium morphogenesis is independent of both Gbx and Fgf. Based on our findings we propose a revised model for the role of Gbx in cerebellar development. PMID:24183937

  3. Cerebellar infarct patterns: The SMART-Medea study

    PubMed Central

    De Cocker, Laurens J.L.; Geerlings, Mirjam I.; Hartkamp, Nolan S.; Grool, Anne M.; Mali, Willem P.; Van der Graaf, Yolanda; Kloppenborg, Raoul P.; Hendrikse, Jeroen

    2015-01-01

    Objective Previous studies on cerebellar infarcts have been largely restricted to acute infarcts in patients with clinical symptoms, and cerebellar infarcts have been evaluated with the almost exclusive use of transversal MR images. We aimed to document the occurrence and 3D-imaging patterns of cerebellar infarcts presenting as an incidental finding on MRI. Methods We analysed the 1.5 Tesla MRI, including 3D T1-weighted datasets, of 636 patients (mean age 62 ± 9 years, 81% male) from the SMART-Medea study. Cerebellar infarct analyses included an assessment of size, cavitation and gliosis, of grey and white matter involvement, and of infarct topography. Results One or more cerebellar infarcts (mean 1.97; range 1–11) were detected in 70 out of 636 patients (11%), with a total amount of 138 infarcts identified, 135 of which showed evidence of cavitation. The average mean axial diameter was 7 mm (range 2–54 mm), and 131 infarcts (95%) were smaller than 20 mm. Hundred-thirty-four infarcts (97%) involved the cortex, of which 12 in combination with subcortical white matter. No infarcts were restricted to subcortical branches of white matter. Small cortical infarcts involved the apex of a deep (pattern 1) or shallow fissure (pattern 2), or occurred alongside one (pattern 3) or opposite sides (pattern 4) of a fissure. Most (87%) cerebellar infarcts were situated in the posterior lobe. Conclusions Small cerebellar infarcts proved to be much more common than larger infarcts, and preferentially involved the cortex. Small cortical infarcts predominantly involved the posterior lobes, showed sparing of subcortical white matter and occurred in characteristic topographic patterns.

  4. 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

  5. Ethanol-Induced Cerebellar Ataxia: Cellular and Molecular Mechanisms.

    PubMed

    Dar, M Saeed

    2015-08-01

    The cerebellum is an important target of ethanol toxicity given that cerebellar ataxia is the most consistent physical manifestation of acute ethanol consumption. Despite the significance of the cerebellum in ethanol-induced cerebellar ataxia (EICA), the cellular and molecular mechanisms underlying EICA are incompletely understood. However, two important findings have shed greater light on this phenomenon. First, ethanol-induced blockade of cerebellar adenosine uptake in rodent models points to a role for adenosinergic A1 modulation of EICA. Second, the consistent observation that intracerebellar administration of nicotine in mice leads to antagonism of EICA provides evidence for a critical role of cerebellar nitric oxide (NO) in EICA reversal. Based on these two important findings, this review discusses the potential molecular events at two key synaptic sites (mossy fiber-granule cell-Golgi cell (MGG synaptic site) and granule cell parallel fiber-Purkinje cell (GPP synaptic site) that lead to EICA. Specifically, ethanol-induced neuronal NOS inhibition at the MGG synaptic site acts as a critical trigger for Golgi cell activation which leads to granule cell deafferentation. Concurrently, ethanol-induced inhibition of adenosine uptake at the GPP synaptic site produces adenosine accumulation which decreases glutamate release and leads to the profound activation of Purkinje cells (PCs). These molecular events at the MGG and GPP synaptic sites are mutually reinforcing and lead to cerebellar dysfunction, decreased excitatory output of deep cerebellar nuclei, and EICA. The critical importance of PCs as the sole output of the cerebellar cortex suggests normalization of PC function could have important therapeutic implications. PMID:25578036

  6. Visually Guided Step Descent in Children with Williams Syndrome

    ERIC Educational Resources Information Center

    Cowie, Dorothy; Braddick, Oliver; Atkinson, Janette

    2012-01-01

    Individuals with Williams syndrome (WS) have impairments in visuospatial tasks and in manual visuomotor control, consistent with parietal and cerebellar abnormalities. Here we examined whether individuals with WS also have difficulties in visually controlling whole-body movements. We investigated visual control of stepping down at a change of…

  7. Imaging calcium waves in cerebellar Bergmann glia.

    PubMed

    Beierlein, Michael

    2013-01-01

    This protocol describes methods for recording synaptically evoked Ca(2+) waves from individual Bergmann glia (BG) in slices of cerebellar cortex. Unlike protoplasmic, star-shaped astrocytes, whose thin processes pose a serious challenge to stable Ca(2+) measurements, BG are large radial cells, with several main processes that run over distances of several hundred micrometers toward the pia and ensheathe thousands of parallel fiber (PF) synapses. Stimulation of PF synapses with brief bursts can trigger long-lasting Ca(2+) responses in BG processes, which can be reliably recorded using a cooled charge-coupled device (CCD) camera. This protocol was developed to enable measurements of Ca(2+) waves in individual BG loaded with a high-affinity Ca(2+) indicator such as Fura-2 for up to 2 h. Because BG recorded in slices rarely display spontaneous (i.e., tetrodotoxin [TTX]-sensitive) or intrinsic Ca(2+) transients, Ca(2+) waves can be evoked repeatedly and reliably, which permits quantitative studies using pharmacological tools. Fluorescence measurements obtained using CCD technology offer a straightforward means of characterizing the mechanisms and potential functional consequences of widespread and long-lasting, store-mediated Ca(2+) increases in astrocytes. PMID:23282638

  8. Rapidly progressive cerebellar ataxia in West Wales.

    PubMed

    Ali, Khalid; Amin, Reem; Yoganathan, Kathir G; Powell, Rob

    2013-01-01

    Progressive multifocal leucoencephalopathy (PML) is a severe demyelinating disease of the central nervous system that is caused by the JC virus infection. It is often fatal or severely disabling. PML exclusively happens in the context of cell-mediated immunosuppression. Prior to the era of HIV, PML was mainly confined to patients with haematological malignancies and rheumatological diseases. The HIV epidemic in the early eighties led to massive expansion in the incidence and prevalence of the disease. PML has also been recognised to happen due to treatment with monoclonal antibodies such as natalizumab, which is used as a disease-modifying agent for relapsing remitting multiple sclerosis and other monoclonal antibodies used in dermatological and haematological conditions. The clinical picture is that of cognitive decline, visual disturbance and hemiparesis. The correct clinicoradiological picture combined with demonstrating the JC virus DNA in the cerebrospinal fluid (CSF) using PCR (PMR) is enough to establish the diagnosis. Brain biopsy is rarely needed. Immune reconstitution represents the mainstay in the treatment of PML. We present a case of a 47-year-old man who presented with progressive cerebellar ataxia. Investigations confirmed PML. He was found to be HIV positive. We also review the literature. PMID:24265345

  9. 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.

  10. 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.

  11. Misdirected horizontal saccades in pan-cerebellar atrophy.

    PubMed

    Shaikh, Aasef G; Ghasia, Fatema F

    2015-08-15

    Saccadic dysmetria is a sensitive marker of cerebellar dysfunction. We discovered misdirected horizontal saccades due to cross-coupled orthogonal (vertical) saccades in siblings with pan-cerebellar atrophy. There was an upward drift in vertical eye position after each cross-coupled downward saccade. Such drifts brought the eyes back to the desired target. Due to strong upward bias, downward compensatory slow movements did not follow cross-coupled upward saccades. There was minimal horizontal cross-coupling associated with vertical saccades. There was a reduced gain of horizontal pursuit causing lag in the horizontal eye movement and subsequent catch-up horizontal saccades. The horizontal catch-up saccades were also associated with vertical cross-coupled eye movements and subsequent drifts. There was no cross-coupling of pursuit eye movements. Our results support the hypothesis emphasizing adaptive cerebellar control of saccade direction. Commands for horizontal saccades trigger not only the activity of the horizontal burst generators, but also the vertical burst neurons. The activity of orthogonal (vertical) burst neurons is canceled by opposing signals under cerebellar supervision. Cerebellar lesions could disrupt such balance between opposing orthogonal signals leading to vertical cross-coupling during horizontal saccade. We speculate that upward drift might result from an imbalance in opposing orthogonal signals at the level of neural integrators. PMID:26070655

  12. Neurodevelopmental outcomes in children with cerebellar malformations: a systematic review.

    PubMed

    Bolduc, Marie-Eve; Limperopoulos, Catherine

    2009-04-01

    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 search of studies describing neurodevelopmental outcomes of cerebellar malformations between January 1997 and December 2007. Overall, the data suggested that children with isolated inferior vermis hypoplasia (IVH) and mega cisterna magna (MCM) have a good developmental outcome, whereas children with molar tooth sign/Joubert syndrome, vermis hypoplasia, pontocerebellar hypoplasia (PCH) type II, and cerebellar agenesis experience moderate to severe global developmental delays. Reports for Dandy-Walker malformation (DWM) were conflicting; however, the presence of a normally lobulated vermis and the absence of associated brain anomalies were associated with a more favourable outcome. Finally, children with isolated cerebellar hypoplasia experienced fewer impairments. Important methodological limitations highlighted include a lack of standardized outcome measure use in 79% of studies and the predominant use of retrospective study designs (85%), with 40% limited to case reports or case-series. In summary, rigorous outcome studies describing the spectrum of disabilities in survivors are urgently needed to accurately delineate the long-term neurodevelopmental consequences of cerebellar malformations. PMID:19191827

  13. Disturbed vestibular-neck interaction in cerebellar disease.

    PubMed

    Kammermeier, S; Kleine, J F; Eggert, T; Krafczyk, S; Büttner, U

    2013-03-01

    Cerebellar dysfunction results in ataxia including postural deficits. Evidence from animal experiments suggests convergence of vestibular and neck-position related inputs in cerebellar midline structures. We investigated 20 ambulatory patients with cerebellar disease for disturbed postural control using posturography during static lateral head turns. Binaural bipolar sine-wave galvanic vestibular stimulation (GVS) was used to evoke specific body movements. The Klockgether clinical score was used to assess the severity of cerebellar dysfunction (4-17 of maximal 35 points). In 12 healthy controls and seven lightly affected patients (score <8), GVS elicited physiologic alternating body sway in the head-frontal plane in seven head-on-trunk positions (0°; 30°, 45° and 60° left and right). Body sway turning with head excursion was progressively attenuated or abolished in more severely affected patients (scores 9-17; r = 0.57, p = 0.008). With most severe impairment, body sway was always in the body-frontal plane irrespective of head turn. A simple clinical test with walking under maximal head turn and closed eyes correlated with posturography data (r = 0.87, p < 0.001) and with Klockgether scores (r = 0.71, p < 0.001). Thus in cerebellar disease, head on trunk position can have a pronounced effect on postural control. PMID:23081756

  14. 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

  15. Exploration of Signal Transduction Pathways in Cerebellar Long-Term Depression by Kinetic Simulation

    Microsoft Academic Search

    Shinya Kuroda; Nicolas Schweighofer; Mitsuo Kawato

    Because multiple molecular signal transduction pathways reg- ulate cerebellar long-term depression (LTD), which is thought to be a possible molecular and cellular basis of cerebellar learn- ing, the systematic relationship between cerebellar LTD and the currently known signal transduction pathways remains ob- scure. To address this issue, we built a new diagram of signal transduction pathways and developed a computational

  16. Student's Corner Post-Infarct Cerebellar Cognitive Affective Syndrome: A Case Report

    Microsoft Academic Search

    Ali Jawaid; Muhammad Ameen Rauf; Uzma Usman; Bhojo A. Khealani

    Post Infarct cerebellar cognitive affective syndrome is a rare disorder, characterized by cognitive impairment in the domains of memory, language, visuo-spatial functioning and affect after cerebellar stroke. We report a case of young female who developed mood alteration and cognitive disturbance following isolated cerebellar infarct. We, therefore, advocate a potential role of cerebellum in regulation of cognition and behaviour in

  17. Behavioral effects of neonatal lesions on the cerebellar system.

    PubMed

    Lalonde, Robert; Strazielle, Catherine

    2015-06-01

    Several rodent models with spontaneous mutations causing cerebellar pathology are impaired in motor functions during the neonatal period, including Grid2(Lc), Rora(sg), Dab1(scm), Girk2(Wv), Lmx1a(dr-sst), Myo5a(dn), Inpp4a(wbl), and Cacna1a(rol) mice as well as shaker and dystonic rats. Deficits are also evident in murine null mutants such as Zic1, Fgfr1/FgFr2, and Xpa/Ercc8. Behavioral deficits are time-dependent following X-irradiated- or aspiration-induced lesions of the cerebellum in rats. In addition, motor functions are deficient after lesions in cerebellar-related pathways. As in animal subjects, sensorimotor disturbances have been described in children with cerebellar lesions. These results underline the importance of the cerebellum and its connections in the development of motor functions. PMID:25907855

  18. Abnormal Head Impulse Test in a Unilateral Cerebellar Lesion

    PubMed Central

    Baek, Seol-Hee; Jung, Jin-Man; Kwon, Do-Young; Park, Moon Ho; Choi, June; Kim, Ji-Soo

    2015-01-01

    Background The findings of head impulse tests (HIT) are usually normal in cerebellar lesions. Case Report A 46-year-old male presented with progressive dizziness and imbalance of 3 weeks duration. The patient exhibited catch-up saccades during bedside horizontal HIT to either side, which was more evident during the rightward HIT. However, results of bithermal caloric tests and rotatory chair test were normal. MRI revealed a lesion in the inferior cerebellum near the flocculus. Conclusions This case provides additional evidence that damage to the flocculus or its connections may impair the vestibulo-ocular reflex only during high-speed stimuli, especially when the stimuli are applied to the contralesional side. By observing accompanying cerebellar signs, the abnormal HIT findings caused by a cerebellar disorder can be distinguished from those produced by peripheral vestibular disorders. PMID:25749819

  19. Congenital cerebellar dysplasia in White Leghorn chickens (Gallus gallus domesticus).

    PubMed

    Nakamura, Sayuri; Ochiai, Kenji; Yabushita, Hiroki; Abe, Asumi

    2014-01-01

    Congenital cerebellar anomalies have been rarely reported in birds. We examined cerebellums with disorganized folia from seven specific-pathogen-free White Leghorn chickens (Gallus gallus domesticus). Islands of heterotopic cortex were distributed from the deeper cortices to the medulla in the cerebellum. The characteristic lesions were composed of randomly admixed components of the cerebellar cortex, including Purkinje cells, a molecular layer and granular cells. Immunofluorescent analysis revealed Purkinje cells with haphazardly extended dendrites and a lack of Bergmann's glial fibres in the foci. Chicken parvovirus, Aino virus and avian retrovirus were not detected in the affected birds by polymerase chain reaction. This is the first report of cerebellar dysplasia in chickens possibly caused by a genetic abnormality. PMID:24498885

  20. Hypertrophic olivary degeneration after resection of a cerebellar tumor.

    PubMed

    Akar, Serra; Drappatz, Jan; Hsu, Liangge; Blinder, Russell A; Black, Peter McL; Kesari, Santosh

    2008-05-01

    We report a case of hypertrophic olivary degeneration due to cerebellar surgery for a low-grade tumor. A 27-year-old female presented with right-sided paresthesias and intermittent leg paresis following a right cerebellar resection of a tumor 2 weeks prior. One month later, her symptoms remained stable while her neurological examination demonstrated slight right hemi-body hypoesthesia and subtle appendicular ataxia in her right upper extremity. An MRI scan revealed a hypertrophied left anterolateral medulla with increased T2 signal and no diffusion abnormality. The T2 hyperintensity and hypertrophy slowly resolved and she clinically improved without further intervention. Hypertrophic olivary degeneration may be mistaken for tumor progression, post-operative vasculopathy or granulation tissue and should be considered in patients undergoing cerebellar surgery. PMID:18217209

  1. Paraneoplastic cerebellar degeneration associated with lymphoepithelial carcinoma of the tonsil

    PubMed Central

    2013-01-01

    Background Paraneoplastic cerebellar degeneration (PCD) is a classical tumor-associated, immune-mediated disease typically associated with gynecological malignancies, small-cell lung-cancer or lymphoma. Case presentation Here we present the case of a 38-year old male with an over 12 months rapidly progressive cerebellar syndrome. Extensive diagnostic workup revealed selective hypermetabolism of the right tonsil in whole-body PET. Histological examination after tonsillectomy demonstrated a lymphoepithelial carcinoma of the tonsil and the tongue base strongly suggesting a paraneoplastic cause of the cerebellar syndrome. To the best of our knowledge this is the first case of an association of a lymphoepithelial carcinoma, a rare pharyngeal tumor, with PCD. Conclusions In cases of classical paraneoplastic syndromes an extensive search for neoplasms should be performed including whole-body PET to detect tumors early in the course of the disease. PMID:24134642

  2. Impaired motor learning performance in cerebellar En-2 mutant mice.

    PubMed

    Gerlai, R; Millen, K J; Herrup, K; Fabien, K; Joyner, A L; Roder, J

    1996-02-01

    Mice homozygous for a null mutation in their En-2 gene exhibit cerebellar neuroanatomical alterations including absence and misplacements of specific fissures and size reduction. The present study investigated cerebellar function by comparing the behavior of age-matched homozygous and heterozygous En-2 mutant and wild-type mice. Motor function of the mutants was found normal in several situations. Habituation to novelty in the open field was not significantly different in mutants. However, in a motor learning paradigm, the rotating rod, the performance of homozygous mutant mice improved significantly less than that of the heterozygous mice which were also significantly impaired compared to wild-type mice. Unlike other cerebellar mutants in which severe motor or sensory defects are obvious, the En-2 mouse model offers a unique tool to study the role of cerebellum in complex behavioral phenomena, including motor learning, without confounding effects. PMID:8652061

  3. Constrained trajectory optimization for lunar landing during the powered descent phase

    Microsoft Academic Search

    Bong-Gyun Park; Daekyu Sangt; Min-Jea Tahku

    2009-01-01

    To design the more accurate trajectory of a soft lunar landing, the constraints on the powered descent sub-phase, such as a breaking phase, an approach phase, a terminal descent phase, have to be considered. In this paper, the trajectory optimization of the lunar landing was performed considering constraints on the sub-phase of the powered descent phase. To convert the optimal

  4. The Huygens Descent Trajectory Working Group and the Reconstruction of the Huygens Probe Entry and Descent Trajectory at Titan

    NASA Astrophysics Data System (ADS)

    Atkinson, David H.; Kazeminejad, Bobby; Lebreton*, Jean-Pierre

    2015-04-01

    Cassini/Huygens, a flagship mission to explore the rings, atmosphere, magnetic field, and moons that make up the Saturn system, is a joint endeavor of NASA, the European Space Agency, and Agenzia Spaziale Italiana. Comprising two spacecraft - a Saturn orbiter built by NASA and a Titan entry/descent probe built by the European Space Agency - Cassini/Huygens was launched in October 1997 and arrived at Saturn in 2004. The Huygens probe parachuted to the surface of Titan in January 2005. During the descent, six science instruments provided measurements of Titan's atmosphere, clouds, and winds, and photographed Titan's surface. It was recognized early in the Huygens program that to correctly interpret and correlate results from the probe science experiments and to provide a reference set of data for ground truth calibration of the Cassini orbiter remote sensing observations, an accurate reconstruction of the probe entry and descent trajectory and surface landing location would be necessary. The Huygens Descent Trajectory Working Group (DTWG) was chartered in 1996 as a subgroup of the Huygens Science Working Team. With membership comprising representatives from all the probe engineering and instrument teams as well as representatives of industry and the Cassini and Huygens Project Scientists, the DTWG presented an organizational framework within which instrument data was shared, the entry and descent trajectory reconstruction implemented, and the trajectory reconstruction efficiently disseminated. The primary goal of the Descent Trajectory Working Group was to develop retrieval methodologies for the probe descent trajectory reconstruction from the entry interface altitude of 1270 km to the surface using navigation data, and engineering and science data acquired by the instruments on the Huygens Probe, and to provide a reconstruction of the Huygens probe trajectory from entry to the surface of Titan that is maximally consistent with all available engineering and science data sets. The official project entry and descent trajectory reconstruction effort was published by the DTWG in 2007. A revised descent trajectory was released in 2010 that accounts for updated measurements of Titan's pole coordinates derived from radar images of Titan taken during Cassini flybys after 2007. The effect of the updated pole positions on Huygens is a southward shift of the trajectory by about 0.3 degrees with a much smaller effect of less than 0.01 degree in the zonal (west to east) direction. The revised Huygens landing coordinates of 192.335 degrees West and 10.573 degrees South with longitude and latitude residuals of respectively 0.035 degrees and 0.007 degrees, respectively, are in excellent agreement with results of recent landing site investigations using visual and radar images from the Cassini VIMS instrument. Acknowledgements *J.-P.L's work was performed while at ESA/ESTEC. DA and BK would like to express appreciation to the European Space Agency's Research and Scientific Support Department for funding the Descent Trajectory Working Group. The work of the Descent Trajectory Working Group would not have been possible without the dedicated efforts of all the Huygens principal investigators and their teams, and the science and engineering data provided from each experiment team, including M. Fulchignoni and the HASI Team, H. Niemann and the GCMS Team, J. Zarnecki and the SSP Team, M. Tomasko and the DISR Team, M. Bird and the DWE Team, and G. Israel and the ACP Team. Additionally, special thanks for many years of support to D.L. Matson, R.T. Mitchell, M. Pérez-Ayúcar, O. Witasse; J. Jones, D. Roth, N. Strange on the Cassini Navigation Team at JPL; A.-M. Schipper and P. Couzin at Thales Alenia; C. Sollazzo, D. Salt, J. Wheadon and S. Standley from the Huygens Ops Team; and R. Trautner and H. Svedhem on the Radar Team at ESTEC.

  5. On the Convergence of Block Coordinate Descent Type Methods

    E-print Network

    Beck, Amir

    On the Convergence of Block Coordinate Descent Type Methods Amir Beck and Luba Tetruashvili April to a certain block taken in a cyclic order. Global sublinear rate of convergence of this method is established also prove a sublinear rate of convergence result for the so-called alternating minimization method

  6. 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.

  7. Elderhostels: Teaching and Learning with Americans of German Descent.

    ERIC Educational Resources Information Center

    Reichmann, Eberhard; Reichmann, Ruth M.

    1998-01-01

    Describes three workshops designed for an Elderhostel program whose audience is largely Americans of German descent and the grandparents of today's students. The workshop topics include an introduction to the German-American experience and German-American studies; German American customs, beliefs, and traditions; and German-American genealogy,…

  8. Robust Wideband Beamforming by the Hybrid Steepest Descent Method

    Microsoft Academic Search

    Konstantinos Slavakis; Isao Yamada

    2007-01-01

    This paper uses the hybrid steepest descent method (HSDM) to design robust smart antennas. Several design criteria as well as robustness are mathematically described by a finite collection of closed convex sets in a real Euclidean space. Desirable beamformers are defined as points of the generalized convex feasible set which is well defined even in the case of inconsistent design

  9. The Challenge of Mars EDL (Entry, Descent, and Landing)

    NASA Technical Reports Server (NTRS)

    Sostaric, Ronald

    2010-01-01

    This slide presentation reviews the some of the challenges of Martian atmospheric entry, descent and landing (EDL) on the surface of Mars. It reviews some of the technological difficulties, and some solutions that are being developed for future unmanned missions with larger payloads than previous landers, and ultimately human spacecraft landing.

  10. A model to 4D descent trajectory guidance

    Microsoft Academic Search

    José Miguel Canino Rodríguez; Luis Gómez Déniz; Jesús García Herrero; Juan Besada Portas

    2007-01-01

    Current standard arrival routes or STARs will require in next years more flexibility to handle the increase of aircraft arrivals and to minimize the related environmental impact applying continuous descent trajectories at idle thrust. To do that, a global optimized 4D trajectory must be followed from the given aircraft position to the terminal gate and tracked in real time. 4D

  11. A random coordinate descent algorithm for optimization problems ...

    E-print Network

    2013-02-06

    Abstract In this paper we propose a variant of the random coordinate descent method for ... chines (where h is the indicator function of some box constrained set) [10,14] and composite ..... distance is finite for the initial iterate x0. Now, we prove ...

  12. Optical diffusion tomography by iterative-coordinate-descent

    E-print Network

    , and its potential for imaging, as an alter- native to x-ray or ultrasonic tomography, in highly scat lower health risks than x-ray radia- tion. Also, suitable sources and detectors are relativelyOptical diffusion tomography by iterative- coordinate-descent optimization in a Bayesian framework

  13. 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.

  14. On the Convergence of Descent Methods for Monotone Variational Inequalities

    E-print Network

    Patriksson, Michael

    of applications in the mathematical and engineering sciences, for example in partial differential equations, equilibrium problems in games, economics and transportation analysis, and nonlinear pro­ gramming, a sufficient decrease in a merit function is obtained through a line search in a feasible descent direction

  15. On the Convergence of Descent Methods for Monotone Variational Inequalities

    E-print Network

    Patriksson, Michael

    its special cases) has a large variety * *of applications in the mathematical and engineering and transportation analysis, and nonli* *near pro- gramming. It is a well-known fact that the problem [VIP(F, X through a line search in a feasible descent direction; natural choices of merit* * functions are f and f

  16. A Portfolio of Outstanding Americans of Mexican Descent.

    ERIC Educational Resources Information Center

    Lelevier, Benjamin, Jr.

    A cross section of Mexican American achievement is presented in a portfolio of 37 portraits of outstanding Americans of Mexican descent. Drawn in black and white on heavy paper stock by Mr. David L. Rodriguez, the sketches are suitable for display purposes. With the likenesses are biographical sketches in both English and Spanish which were…

  17. S2CD: Semi-Stochastic Coordinate Descent Jakub Konecny

    E-print Network

    Edinburgh, University of

    .richtarik@ed.ac.uk Abstract We propose a novel reduced variance method--semi-stochastic coordinate descent (S2CD that the method enjoys a reduced variance property. The complexity of the method is the sum of two terms: O(n log convex functions: f(x) = 1 n i fi(x). Our method first performs a deterministic step (computation

  18. 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

  19. LANDER program manual: A lunar ascent and descent simulation

    NASA Technical Reports Server (NTRS)

    1988-01-01

    LANDER is a computer program used to predict the trajectory and flight performance of a spacecraft ascending or descending between a low lunar orbit of 15 to 500 nautical miles (nm) and the lunar surface. It is a three degree-of-freedom simulation which is used to analyze the translational motion of the vehicle during descent. Attitude dynamics and rotational motion are not considered. The program can be used to simulate either an ascent from the Moon or a descent to the Moon. For an ascent, the spacecraft is initialized at the lunar surface and accelerates vertically away from the ground at full thrust. When the local velocity becomes 30 ft/s, the vehicle turns downrange with a pitch-over maneuver and proceeds to fly a gravity turn until Main Engine Cutoff (MECO). The spacecraft then coasts until it reaches the requested holding orbit where it performs an orbital insertion burn. During a descent simulation, the lander begins in the holding orbit and performs a deorbit burn. It then coasts to pericynthion, where it reignites its engines and begins a gravity turn descent. When the local horizontal velocity becomes zero, the lander pitches up to a vertical orientation and begins to hover in search of a landing site. The lander hovers for a period of time specified by the user, and then lands.

  20. Neurogenic Cardiopulmonary Complications Associated with Spontaneous Cerebellar Hemorrhage

    Microsoft Academic Search

    Yui-Rwei Young; Chien-Chang Lee; Bor-Fuh Sheu; Shy-Shin Chang

    2007-01-01

    Introduction  Neurogenic cardiopulmonary complications associated with acute brain injury other then subarachnoid hemorrhage were seldom\\u000a reported, especially in the pediatric population. We report a child who developed cardiac arrhythmia, severe myocardial injury\\u000a and neurogenic pulmonary edema after cerebellar hemorrhage.\\u000a \\u000a \\u000a \\u000a Methods and results  An 11-year-old girl had abrupt onset of spontaneous cerebellar hemorrhage presented with a fulminant picture of hypertension,\\u000a supraventricular tachyarrhythmia, markedly

  1. 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

  2. Cerebellar cysts in children: a pattern recognition approach.

    PubMed

    Boltshauser, Eugen; Scheer, Ianina; Huisman, Thierry A G M; Poretti, Andrea

    2015-06-01

    Cerebellar cysts may be seen in selected genetic disorders and acquired anomalies. Here, we review our experience, excluding cystic tumors and parasitic cysts. The pathogenesis is heterogeneous: Cysts may involve/represent normal structures (e.g., Virchow-Robin spaces), be "destructive" (such as in some types of pontocerebellar hypoplasias), "malformative" (such as in some forms of congenital muscular dystrophies and GPR56-related migration disorders), or "disruptive" (such as in some cerebellar dysplasias). The provided checklist may be useful in deciding targeted diagnostic workup. PMID:25504001

  3. 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.

  4. RITD - Adapting Mars Entry, Descent and Landing System for Earth

    NASA Astrophysics Data System (ADS)

    Heilimo, Jyri; Harri, Ari-Matti; Aleksashkin, Sergei; Koryanov, Valeri; Arruego, Ignacio; Schmidt, Walter; Haukka, Harri; Finchenko, Valeri; Martynov, Maxim; Ponomarenko, Andrey; Kazakovtsev, Victor; Martin, Susana

    2015-04-01

    We have developed an atmospheric re-entry and descent system concept based on inflatable hypersonic decelerator techniques that were originally developed for Mars. The ultimate goal of this EU-funded RITD-project (Re-entry: Inflatable Technology Development) was to assess the benefits of this technology when deploying small payloads from low Earth orbits to the surface of the Earth with modest costs. The principal goal was to assess and develop a preliminary EDLS design for the entire relevant range of aerodynamic regimes expected to be encountered in Earth's atmosphere during entry, descent and landing. Low Earth Orbit (LEO) and even Lunar applications envisaged include the use of the EDLS approach in returning payloads of 4-8 kg down to the surface. Our development and assessments show clearly that this kind of inflatable technology originally developed for the Martian atmosphere, is feasible for use by Earth entry and descent applications. The preliminary results are highly promising indicating that the current Mars probe design could be used as it is for the Earth. According tp our analyses, the higher atmospheric pressure at an altitude of 12 km and less requires an additional pressurizing device for the in atable system increasing the entry mass by approximately 2 kg. These analyses involved the calculation of 120 different atmospheric entry and descent trajectories. The analysis of the existing technologies and current trends have indicated that the kind of inflatable technology pursued by RITD has high potential to enhance the European space technology expertise. This kind of technology is clearly feasible for utilization by Earth entry and descent applications.

  5. 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.

  6. 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

  7. Translational Approach to Behavioral Learning: Lessons from Cerebellar Plasticity

    PubMed Central

    Cheron, Guy; Dan, Bernard; Márquez-Ruiz, Javier

    2013-01-01

    The role of cerebellar plasticity has been increasingly recognized in learning. The privileged relationship between the cerebellum and the inferior olive offers an ideal circuit for attempting to integrate the numerous evidences of neuronal plasticity into a translational perspective. The high learning capacity of the Purkinje cells specifically controlled by the climbing fiber represents a major element within the feed-forward and feedback loops of the cerebellar cortex. Reciprocally connected with the basal ganglia and multimodal cerebral domains, this cerebellar network may realize fundamental functions in a wide range of behaviors. This review will outline the current understanding of three main experimental paradigms largely used for revealing cerebellar functions in behavioral learning: (1) the vestibuloocular reflex and smooth pursuit control, (2) the eyeblink conditioning, and (3) the sensory envelope plasticity. For each of these experimental conditions, we have critically revisited the chain of causalities linking together neural circuits, neural signals, and plasticity mechanisms, giving preference to behaving or alert animal physiology. Namely, recent experimental approaches mixing neural units and local field potentials recordings have demonstrated a spike timing dependent plasticity by which the cerebellum remains at a strategic crossroad for deciphering fundamental and translational mechanisms from cellular to network levels. PMID:24319600

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

    E-print Network

    Bellugi, Ursula

    Williams syndrome (WMS) is a rare genetic disorder characterized by relative preservations of language, and visuospatial processing. Subjects with WMS also display hypersocial behavior and excessive linguistic affect in the brain volumes of subjects with WMS compared with normal controls, but with preservations in cerebellar

  9. 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…

  10. 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

  11. The advantages of linear information processing for cerebellar computation.

    PubMed

    Walter, Joy T; Khodakhah, Kamran

    2009-03-17

    Purkinje cells can encode the strength of parallel fiber inputs in their firing by using 2 fundamentally different mechanisms, either as pauses or as linear increases in firing rate. It is not clear which of these 2 encoding mechanisms is used by the cerebellum. We used the pattern-recognition capacity of Purkinje cells based on the Marr-Albus-Ito theory of cerebellar learning to evaluate the suitability of the linear algorithm for cerebellar information processing. Here, we demonstrate the simplicity and versatility of pattern recognition in Purkinje cells linearly encoding the strength of parallel fiber inputs in their firing rate. In contrast to encoding patterns with pauses, Purkinje cells using the linear algorithm could recognize a large number of both synchronous and asynchronous input patterns in the presence or absence of inhibitory synaptic transmission. Under all conditions, the number of patterns recognized by Purkinje cells using the linear algorithm was greater than that achieved by encoding information in pauses. Linear encoding of information also allows neurons of deep cerebellar nuclei to use a simple averaging mechanism to significantly increase the computational capacity of the cerebellum. We propose that the virtues of the linear encoding mechanism make it well suited for cerebellar computation. PMID:19234116

  12. 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

  13. 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…

  14. Variation in Brain Organization and Cerebellar Foliation in Chondrichthyans: Batoids

    Microsoft Academic Search

    Thomas J. Lisney; Kara E. Yopak; John C. Montgomery; Shaun P. Collin

    2008-01-01

    Interspecific variation in relative brain size (encephalization), the relative size of the five major brain areas (the telencephalon, diencephalon, mesencephalon, cerebellum, and medulla) and the level of cerebellar foliation was assessed in over 20 representative species of batoid (skates and rays), from eight families. Using species as independent data points and phylogenetically independent contrasts, relationships among each of the neuroanatomical

  15. Robust and fast learning for fuzzy cerebellar model articulation controllers

    Microsoft Academic Search

    Shun-feng Su; Zne-jung Lee; Yan-ping Wang

    2006-01-01

    In this paper, the online learning capability and the robust property for the learning algorithms of cerebellar model articulation controllers (CMAC) are discussed. Both the traditional CMAC and fuzzy CMAC are considered. In the study, we find a way of embedding the idea of M-estimators into the CMAC learning algorithms to provide the robust property against outliers existing in training

  16. Cerebellar autoregulation dynamics in humans Matthias Reinhard1

    E-print Network

    Timmer, Jens

    Knowledge on autoregulation of cerebellar blood flow in humans is scarce. This study investigated whether. Journal of Cerebral Blood Flow & Metabolism (2008) 28, 1605­1612; doi:10.1038/jcbfm.2008.48; published capacity of blood flow autoregulation in migraine (Kruit et al, 2005). Also prodromal symp- toms of syncope

  17. Cerebellar autoregulation dynamics in humans Matthias Reinhard1

    E-print Network

    Timmer, Jens

    Knowledge on autoregulation of cerebellar blood flow in humans is scarce. This study investigated whether. Journal of Cerebral Blood Flow & Metabolism advance online publication, 21 May 2008; doi:10.1038/jcbfm capacity of blood flow autoregulation in migraine (Kruit et al, 2005). Also prodromal symp- toms of syncope

  18. A Case of Cerebellar Capillary Hemangioma with Multiple Cysts

    Microsoft Academic Search

    Atsushi Uyama; Atsuhumi Kawamura; Hideyuki Akiyama; Satoshi Nakamizo; Kazuki Yamamoto; Tatsuya Nagashima; Toshiyuki Uetani; Hiroki Takeda; Makiko Yoshida

    2008-01-01

    Intracranial capillary hemangiomas are very rare, though several spinal capillary hemangiomas have recently been reported. We report here a case of intracranial capillary hemangioma with multiple cysts and review the current literature of similar cases. A 4-month-old girl was referred to our hospital for treatment of hydrocephalus and a cerebellar mass lesion. She presented with hemangiomas distributed widely over the

  19. Familial cerebellar ataxia presenting with down beat nystagmus.

    PubMed Central

    Schott, G D

    1980-01-01

    Two brothers are described who during their fourth decade presented with isolated down beat nystagmus and later developed a progressive cerebellar ataxia. The nature of this unusual oculomotor disorder and its rare occurrence in other inherited conditions are discussed. PMID:7381864

  20. Surgery of cerebellar astrocytomas, ependymomas and medulloblastomas in children

    Microsoft Academic Search

    O. Heiskanen; J. Lehtosalo

    1985-01-01

    Summary A report is given on 118 children operated on for cerebellar astrocytoma, ependymoma or medulloblastoma in 1968–1982. During the first period (1968–1975) when the diagnosis was based on ventriculography and the operation performed later on the same day, the surgical mortality was 5%, 22%, and 16% respectively in these tumours. In the period since 1976, during which the diagnosis

  1. Recurrent cerebellar architecture solves the motor-error problem

    Microsoft Academic Search

    John Porrill; Paul Dean; James V. Stone

    2004-01-01

    Current views of cerebellar function have been heavily influenced by the models of Marr and Albus, who suggested that the climbing fibre input to the cerebellum acts as a teaching signal for motor learning. It is commonly assumed that this teaching signal must be motor error (the difference between actual and correct motor command), but this approach requires complex neural

  2. Zic2 Controls Cerebellar Development in Cooperation with Zic1

    Microsoft Academic Search

    Jun Aruga; Takashi Inoue; Jun Hoshino; Katsuhiko Mikoshiba

    2002-01-01

    Mouse Zic genes encode zinc finger proteins and are ex- pressed in the developing and mature CNS. Reduced expres- sion of Zic2 in mice results in spina bifida and holoprosen- cephaly. However, the disruption of Zic1, a strong homolog of Zic2 that has an overlapping expression pattern, results in cerebellar malformation with no apparent abnormalities in the forebrain or in

  3. 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

  4. 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

  5. Increase in B-cell-activation factor (BAFF) and IFN-? productions by tonsillar mononuclear cells stimulated with deoxycytidyl-deoxyguanosine oligodeoxynucleotides (CpG-ODN) in patients with IgA nephropathy

    Microsoft Academic Search

    Takashi Goto; Nobuyuki Bandoh; Tomoki Yoshizaki; Hayabusa Nozawa; Miki Takahara; Seigo Ueda; Tatsuya Hayashi; Yasuaki Harabuchi

    2008-01-01

    IgA nephropathy (IgAN), the most common form of primary glomerulonephritis, is recognized as a tonsil-related diseases since it often gets worse after and\\/or during acute tonsillitis and the disease progression is often prevented by tonsillectomy. Although several reports showed an increase in IgA production of tonsillar mononuclear cells (TMCs), its mechanism has not yet been fully clarified. Recently, B-cell-activation factor

  6. Cerebellar Motor Learning: When Is Cortical Plasticity Not Enough?

    PubMed Central

    Porrill, John; Dean, Paul

    2007-01-01

    Classical Marr-Albus theories of cerebellar learning employ only cortical sites of plasticity. However, tests of these theories using adaptive calibration of the vestibulo–ocular reflex (VOR) have indicated plasticity in both cerebellar cortex and the brainstem. To resolve this long-standing conflict, we attempted to identify the computational role of the brainstem site, by using an adaptive filter version of the cerebellar microcircuit to model VOR calibration for changes in the oculomotor plant. With only cortical plasticity, introducing a realistic delay in the retinal-slip error signal of 100 ms prevented learning at frequencies higher than 2.5 Hz, although the VOR itself is accurate up to at least 25 Hz. However, the introduction of an additional brainstem site of plasticity, driven by the correlation between cerebellar and vestibular inputs, overcame the 2.5 Hz limitation and allowed learning of accurate high-frequency gains. This “cortex-first” learning mechanism is consistent with a wide variety of evidence concerning the role of the flocculus in VOR calibration, and complements rather than replaces the previously proposed “brainstem-first” mechanism that operates when ocular tracking mechanisms are effective. These results (i) describe a process whereby information originally learnt in one area of the brain (cerebellar cortex) can be transferred and expressed in another (brainstem), and (ii) indicate for the first time why a brainstem site of plasticity is actually required by Marr-Albus type models when high-frequency gains must be learned in the presence of error delay. PMID:17967048

  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. 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

  9. Characteristic changes of cerebellar proteins associated with cerebellar hypoplasia in jaundiced Gunn rats and the prevention of these by phototherapy

    Microsoft Academic Search

    S. Kashiwamata; S. Aono; R. K. Semba

    1980-01-01

    Summary In the cerebellar particulate fractions from Gunn rat homozygotes 3 protein bands with apparent mol.wts of 250,000, 50,000 and 33,000 in SDS-polyacrylamide gel disc electrophoresis underwent major changes, and phototherapy of the newborns could effectively prevent the changes.

  10. 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.

  11. 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-Ribière-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.

  12. 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

  13. Helicopter optimal descent and landing after power loss

    NASA Technical Reports Server (NTRS)

    Johnson, W.

    1977-01-01

    An optimal control solution is obtained for the descent and landing of a helicopter after the loss of power in level flight. The model considers the helicopter vertical velocity, horizontal velocity, and rotor speed; and it includes representations of ground effect, rotor inflow time lag, pilot reaction time, rotor stall, and the induced velocity curve in the vortex ring state. The control (rotor thrust magnitude and direction) required to minimize the vertical and horizontal velocity at contact with the ground is obtained using nonlinear optimal control theory. It is found that the optimal descent after power loss in hover is a purely vertical flight path. Good correlation, even quantitatively, is found between the calculations and (non-optimal) flight test results.

  14. Scaling Up Coordinate Descent Algorithms for Large ?1 Regularization Problems

    SciTech Connect

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

    2012-07-03

    We present a generic framework for parallel coordinate descent (CD) algorithms that has as special cases the original sequential algorithms of Cyclic CD and Stochastic CD, as well as the recent parallel Shotgun algorithm of Bradley et al. We introduce two novel parallel algorithms that are also special cases---Thread-Greedy CD and Coloring-Based CD---and give performance measurements for an OpenMP implementation of these.

  15. A Variable Neighbourhood Descent Algorithm for the Redundancy Allocation Problem

    Microsoft Academic Search

    Yun-Chia Liang; Chia-Chuan Wu

    This paper presents the first known application of a meta-heuristic algorithm, variable neighbour- hood descent (VND), to the redundancy allocation problem (RAP). The RAP, a well-known NP-hard problem, has been the subject of much prior work, generally in a restricted form where each subsystem must consist of identical components. The newer meta-heuristic methods overcome this limitation and offer a practical

  16. Energy and emission assessments of continuous descent approach

    Microsoft Academic Search

    Enis T. Turgut; Oznur Usanmaz; Ali Ozan Canarslanlar; Ozlem Sahin

    2010-01-01

    Purpose – Continuous descent approach (CDA) is a method, which allows the aircraft flying its individual optimal vertical profile down to runway threshold with engines operating at low-thrust power. The main objective of this paper is to provide less-fuel consumption, less noise and less emission with using CDA procedures instead of conventional procedures. Design\\/methodology\\/approach – Conventional and CDA procedures were

  17. 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. PMID:25504986

  18. 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

  19. Entry, Descent, and Landing Performance of the Mars Phoenix Lander

    NASA Technical Reports Server (NTRS)

    Desai, Prasun N.; Prince, Jill L.; Wueen, Eric M.; Cruz, Juan R.; Grover, Myron R.

    2008-01-01

    On May 25, 2008, the Mars Phoenix Lander successfully landed on the northern arctic plains of Mars. An overview of a preliminary reconstruction analysis performed on each entry, descent, and landing phase to assess the performance of Phoenix as it descended is presented and a comparison to pre-entry predictions is provided. The landing occurred 21 km further downrange than the predicted landing location. Analysis of the flight data revealed that the primary cause of Phoenix s downrange landing was a higher trim total angle of attack during the hypersonic phase of the entry, which resulted in Phoenix flying a slightly lifting trajectory. The cause of this higher trim attitude is not known at this time. Parachute deployment was 6.4 s later than prediction. This later deployment time was within the variations expected and is consistent with a lifting trajectory. The parachute deployment and inflation process occurred as expected with no anomalies identified. The subsequent parachute descent and powered terminal landing also behaved as expected. A preliminary reconstruction of the landing day atmospheric density profile was found to be lower than the best apriori prediction, ranging from a few percent less to a maximum of 8%. A comparison of the flight reconstructed trajectory parameters shows that the actual Phoenix entry, descent, and landing was close to pre-entry predictions. This reconstruction investigation is currently ongoing and the results to date are in the process of being refined.

  20. 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

  1. Medial cerebellar nuclear projections and activity patterns link cerebellar output to orofacial and respiratory behavior

    PubMed Central

    Lu, Lianyi; Cao, Ying; Tokita, Kenichi; Heck, Detlef H.; Jr., John D. Boughter

    2013-01-01

    There is ample evidence that the cerebellum plays an important role in coordinating both respiratory and orofacial movements. However, the pathway by which the cerebellum engages brainstem substrates underlying these movements is not well understood. We used tract-tracing techniques in mice to show that neurons in the medial deep cerebellar nucleus (mDCN) project directly to these putative substrates. Injection of an anterograde tracer into the mDCN produced terminal labeling in the ventromedial medullary reticular formation, which was stronger on the contralateral side. Correspondingly, injection of retrograde tracers into these same areas resulted in robust neuronal cell labeling in the contralateral mDCN. Moreover, injection of two retrograde tracers at different rostral–caudal brainstem levels resulted in a subset of double-labeled cells, indicating that single mDCN neurons collateralize to multiple substrates. Using an awake and behaving recording preparation, we show that spiking activity in mDCN neurons is correlated with respiratory and orofacial behaviors, including whisking and fluid licking. Almost half of the recorded neurons showed activity correlated with more than one behavior, suggesting that these neurons may in fact modulate multiple brainstem substrates. Collectively, these results describe a potential pathway through which the cerebellum could modulate and coordinate respiratory and orofacial behaviors. PMID:23565078

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

    NASA Technical Reports Server (NTRS)

    Way, David W.; Powell, Richard W.; Chen, Allen; Steltzner, Adam D.; San Martin, Alejandro M.; Burkhart, Paul D.; mendeck, Gavin F.

    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. 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.

  3. GABAergic neurons in cerebellar interposed nucleus modulate cellular and humoral immunity via hypothalamic and sympathetic pathways.

    PubMed

    Lu, Jian-Hua; Wang, Xiao-Qin; Huang, Yan; Qiu, Yi-Hua; Peng, Yu-Ping

    2015-06-15

    Our previous work has shown that cerebellar interposed nucleus (IN) modulates immune function. Herein, we reveal mechanism underlying the immunomodulation. Treatment of bilateral cerebellar IN of rats with 3-mercaptopropionic acid (3-MP), a glutamic acid decarboxylase antagonist that reduces ?-aminobutyric acid (GABA) synthesis, enhanced cellular and humoral immune responses to bovine serum albumin, whereas injection of vigabatrin, a GABA-transaminase inhibitor that inhibits GABA degradation, in bilateral cerebellar IN attenuated the immune responses. The 3-MP or vigabatrin administrations in the cerebellar IN decreased or increased hypothalamic GABA content and lymphoid tissues' norepinephrine content, respectively, but did not alter adrenocortical or thyroid hormone levels in serum. In addition, a direct GABAergic projection from cerebellar IN to hypothalamus was found. These findings suggest that GABAergic neurons in cerebellar IN regulate immune system via hypothalamic and sympathetic pathways. PMID:26004153

  4. Short latency cerebellar modulation of the basal ganglia

    PubMed Central

    Chen, Christopher H.; Fremont, Rachel; Arteaga-Bracho, Eduardo E.; Khodakhah, Kamran

    2014-01-01

    The graceful, purposeful motion of our body is an engineering feat which remains unparalleled in robotic devices using advanced artificial intelligence. Much of the information required for complex movements is generated by the cerebellum and the basal ganglia in conjunction with the cortex. Cerebellum and basal ganglia have been thought to communicate with each other only through slow multi-synaptic cortical loops, begging the question as to how they coordinate their outputs in real time. Here we show in mice that the cerebellum rapidly modulates the activity of the striatum via a disynaptic pathway. Under physiological conditions this short latency pathway is capable of facilitating optimal motor control by allowing the basal ganglia to incorporate time-sensitive cerebellar information and by guiding the sign of cortico-striatal plasticity. Conversely, under pathological condition this pathway relays aberrant cerebellar activity to the basal ganglia to cause dystonia. PMID:25402853

  5. 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

  6. 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

  7. Cerebellar networks with the cerebral cortex and basal ganglia

    PubMed Central

    Bostan, Andreea C.; Dum, Richard P.; Strick, Peter L.

    2013-01-01

    The dominant view of cerebellar function has been that it is exclusively concerned with motor control and coordination. Recent results from neuroanatomical, behavioral and imaging studies have profoundly changed this view. Neuroanatomical studies using virus transneuronal tracers have demonstrated that the output from the cerebellum reaches vast areas of the neocortex, including regions of prefrontal and posterior parietal cortex. Furthermore, it has recently become clear that the cerebellum is reciprocally connected with the basal ganglia, indicating that the two subcortical structures are part of a densely interconnected network. Altogether, these results provide the neuroanatomical substrate for cerebellar involvement in non-motor functions mediated by the prefrontal and posterior parietal cortex, as well as in processes traditionally associated with the basal ganglia. PMID:23579055

  8. Cerebellar Schistosomiasis: A Case Report with Clinical Analysis

    PubMed Central

    Lei, Ding; Mao, Qing

    2009-01-01

    The authors report here a rare case of cerebellar schistosomiasis identified by pathological diagnosis, lacking extracranial involvement. The clinical symptoms included headache, dizziness, and nausea. Studies in blood were normal and no parasite eggs were detected in stool. Computed tomography of brains showed hypodense signal, and magnetic resonance imaging showed isointense signal on T1-weighted images, hyperintense signal on T2-weighted images, and intensely enhancing nodules in the right cerebellum after intravenous administration of gadolinium. A high-grade glioma was suspected, and an operation was performed. The pathologic examination of the biopsy specimen revealed schistosomal granulomas scattered within the parenchyma of the cerebellum. The definitive diagnosis was cerebellar schistosomiasis japonica. A standard use of praziquantel and corticosteroid drugs was applied, and the prognosis was good. When the pattern of imaging examinations is present as mentioned above, a diagnosis of brain schistosomiasis should be considered. PMID:19290092

  9. Hydranencephaly associated with cerebellar involvement and bilateral microphthalmia and colobomas.

    PubMed

    Taori, Kishor B; Sargar, Kiran M; Disawal, Amit; Chhadi, Shyam; Rathod, Jawahar

    2011-02-01

    Hydranencephaly is an encephaloclastic central nervous system disorder characterised by severe destruction of the cerebral hemispheres with preservation of posterior fossa structures. We present MRI and neurosonography features of a unique case of hydranencephaly involving cerebellum (in the form of complete liquefaction of cerebellar hemispheres) and cerebral hemispheres with associated bilateral microphthalmia and ocular colobomas. This is an exceptional case as to the best to our knowledge. In humans, such a severe involvement of cerebellum has not been reported in cases of hydranencephaly. It is essential to distinguish hydranencephaly from gross hydrocephalus, as treatment and prognosis of the two are totally different. During differentiation, it is important to remember that severe cerebellar involvement can be seen in hydranencephaly. PMID:20577730

  10. 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

  11. Cerebellar ataxia with elevated cerebrospinal free sialic acid (CAFSA)

    PubMed Central

    Sedel, F.; Vanderver, A.; Engelke, U. F. H.; Barritault, J.; Yang, B. Z.; Kulkarni, B.; Adams, D. R.; Clot, F.; Ding, J. H.; Kaneski, C. R.; Verheijen, F. W.; Smits, B. W.; Seguin, F.; Brice, A.; Vanier, M. T.; Huizing, M.; Schiffmann, R.; Durr, A.; Wevers, R. A.

    2009-01-01

    In order to identify new metabolic abnormalities in patients with complex neurodegenerative disorders of unknown aetiology, we performed high resolution in vitro proton nuclear magnetic resonance spectroscopy on patient cerebrospinal fluid (CSF) samples. We identified five adult patients, including two sisters, with significantly elevated free sialic acid in the CSF compared to both the cohort of patients with diseases of unknown aetiology (n = 144; P < 0.001) and a control group of patients with well-defined diseases (n = 91; P < 0.001). All five patients displayed cerebellar ataxia, with peripheral neuropathy and cognitive decline or noteworthy behavioural changes. Cerebral MRI showed mild to moderate cerebellar atrophy (5/5) as well as white matter abnormalities in the cerebellum including the peridentate region (4/5), and at the periventricular level (3/5). Two-dimensional gel analyses revealed significant hyposialylation of transferrin in CSF of all patients compared to age-matched controls (P < 0.001)—a finding not present in the CSF of patients with Salla disease, the most common free sialic acid storage disorder. Free sialic acid content was normal in patients’ urine and cultured fibroblasts as were plasma glycosylation patterns of transferrin. Analysis of the ganglioside profile in peripheral nerve biopsies of two out of five patients was also normal. Sequencing of four candidate genes in the free sialic acid biosynthetic pathway did not reveal any mutation. We therefore identified a new free sialic acid syndrome in which cerebellar ataxia is the leading symptom. The term CAFSA is suggested (cerebellar ataxia with free sialic acid). PMID:19153153

  12. Direct transcranial puncture for Onyx embolization of a cerebellar hemangioblastoma.

    PubMed

    Ding, Dale; Starke, Robert M; Evans, Avery J; Liu, Kenneth C

    2014-06-01

    Intracranial hemangioblastomas are benign but hypervascular tumors, most commonly located in the cerebellum, which are difficult to resect without significant operative blood loss. While preoperative embolization may decrease the amount of operative bleeding, the vascular supply of cerebellar hemangioblastomas frequently precludes safe embolization by an endovascular route due to the risk of thromboembolic vertebrobasilar infarction. Direct puncture embolization overcomes many of the limitations of endovascular embolization but its safety and feasibility for intracranial tumors is unknown. We report a 48-year-old man who was diagnosed with a large cerebellar mass after presenting with headaches and gait ataxia. Based on diagnostic angiography, which demonstrated a highly vascular tumor supplied by the posterior inferior cerebellar and posterior meningeal arteries, we decided to embolize the tumor by a direct transcranial puncture approach. After trephinating the skull in a standard fashion, a catheter-needle construct, composed of an Echelon 10 microcatheter (ev3 Endovascular, Plymouth, MN, USA) placed into a 21-gauge spinal needle, was inserted into the tumor under biplanar angiographic guidance. Using continuous angiographic monitoring, 9cc of Onyx 34 (ev3 Endovascular) was injected through the catheter, resulting in 75% tumor devascularization without evidence of complications. The patient was taken directly to surgery where a gross total resection of the hemangioblastoma was achieved with an acceptable operative blood loss. At his 2 year follow-up, the patient was neurologically intact without neuroimaging evidence of residual tumor. We describe, to our knowledge, the first case of direct transcranial puncture for preoperative embolization of a cerebellar hemangioblastoma. PMID:24370504

  13. Torsin A Localization in the Mouse Cerebellar Synaptic Circuitry

    PubMed Central

    Ponterio, Giulia; Tassone, Annalisa; Sciamanna, Giuseppe; Bonsi, Paola; Pisani, Antonio; Mandolesi, Georgia

    2013-01-01

    Torsin A (TA) is a ubiquitous protein belonging to the superfamily of proteins called “ATPases associated with a variety of cellular activities” (AAA+ ATPase). To date, a great deal of attention has been focused on neuronal TA since its mutant form causes early-onset (DYT1) torsion dystonia, an inherited movement disorder characterized by sustained muscle contractions and abnormal postures. Interestingly, it has been proposed that TA, by interacting with the cytoskeletal network, may contribute to the control of neurite outgrowth and/or by acting as a chaperone at synapses could affect synaptic vesicle turnover and neurotransmitter release. Accordingly, both its peculiar developmental expression in striatum and cerebellum and evidence from DYT1 knock-in mice suggest that TA may influence dendritic arborization and synaptogenesis in the brain. Therefore, to better understand TA function a detailed description of its localization at synaptic level is required. Here, we characterized by means of rigorous quantitative confocal analysis TA distribution in the mouse cerebellum at postnatal day 14 (P14), when both cerebellar synaptogenesis and TA expression peak. We observed that the protein is broadly distributed both in cerebellar cortex and in the deep cerebellar nuclei (DCN). Of note, Purkinje cells (PC) express high levels of TA also in the spines and axonal terminals. In addition, abundant expression of the protein was found in the main GABA-ergic and glutamatergic inputs of the cerebellar cortex. Finally, TA was observed also in glial cells, a cellular population little explored so far. These results extend our knowledge on TA synaptic localization providing a clue to its potential role in synaptic development. PMID:23840813

  14. Calcium control of transmitter release at a cerebellar synapse

    Microsoft Academic Search

    I. M. Mintz; B. L. Sabatini; W. G. Regehr

    1995-01-01

    The manner in which presynaptic Ca2+ influx controls the release of neurotransmitter was investigated at the granule cell to Purkinje cell synapse in rat cerebellar slices. Excitatory postsynaptic currents were measured using whole-cell voltage clamp, and changes in presynaptic Ca2+ influx were determined with the Ca2+-sensitive dye furaptra. We manipulated presynaptic Ca2+ entry by altering external Ca2+ levels and by

  15. 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

  16. Hydranencephaly associated with cerebellar involvement and bilateral microphthalmia and colobomas

    Microsoft Academic Search

    Kishor B. Taori; Kiran M. Sargar; Amit Disawal; Shyam Chhadi; Jawahar Rathod

    2011-01-01

    Hydranencephaly is an encephaloclastic central nervous system disorder characterised by severe destruction of the cerebral\\u000a hemispheres with preservation of posterior fossa structures. We present MRI and neurosonography features of a unique case\\u000a of hydranencephaly involving cerebellum (in the form of complete liquefaction of cerebellar hemispheres) and cerebral hemispheres\\u000a with associated bilateral microphthalmia and ocular colobomas. This is an exceptional case

  17. 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

  18. Evidence for Cerebellar Contributions to Adaptive Plasticity in Speech Perception.

    PubMed

    Guediche, Sara; Holt, Lori L; Laurent, Patryk; Lim, Sung-Joo; Fiez, Julie A

    2015-07-01

    Human speech perception rapidly adapts to maintain comprehension under adverse listening conditions. For example, with exposure listeners can adapt to heavily accented speech produced by a non-native speaker. Outside the domain of speech perception, adaptive changes in sensory and motor processing have been attributed to cerebellar functions. The present functional magnetic resonance imaging study investigates whether adaptation in speech perception also involves the cerebellum. Acoustic stimuli were distorted using a vocoding plus spectral-shift manipulation and presented in a word recognition task. Regions in the cerebellum that showed differences before versus after adaptation were identified, and the relationship between activity during adaptation and subsequent behavioral improvements was examined. These analyses implicated the right Crus I region of the cerebellum in adaptive changes in speech perception. A functional correlation analysis with the right Crus I as a seed region probed for cerebral cortical regions with covarying hemodynamic responses during the adaptation period. The results provided evidence of a functional network between the cerebellum and language-related regions in the temporal and parietal lobes of the cerebral cortex. Consistent with known cerebellar contributions to sensorimotor adaptation, cerebro-cerebellar interactions may support supervised learning mechanisms that rely on sensory prediction error signals in speech perception. PMID:24451660

  19. A Subtraction Mechanism of Temporal Coding in Cerebellar Cortex

    PubMed Central

    Kalmbach, Brian E.; Voicu, Horatiu; Ohyama, Tatsuya; Mauk, Michael D.

    2011-01-01

    The temporally specific learning displayed by the cerebellum facilitates mechanistic analysis of neural timing and temporal coding. We report evidence for a subtraction-like mechanism of temporal coding in cerebellar cortex where activity in a subset of granule cells specifically codes the interval between the offset of two mossy fiber inputs. In a large-scale cerebellar simulation, cessation of one of two ongoing mossy fiber inputs produces a robust temporal code in the population of granule cells. This activity supports simulation learning in response to temporal patterns of stimuli, even when those same stimuli do not support learning when presented individually. Using stimulation of mossy fiber inputs to the cerebellum as training stimuli in rabbits, we confirmed these unusual predictions in a cerebellum-dependent form of learning. Analysis of the simulations reveals a specific working hypothesis for this temporal subtraction process that involves interactions between granule cells and the inhibitory Golgi cells. The results suggest how feed-forward inhibition, such as that present in the cerebellar cortex, can contribute to temporal coding. PMID:21307241

  20. Cerebellar Cortical Lamination and Foliation Require Cyclin A2

    PubMed Central

    Otero, José Javier; Kalaszczynska, Ilona; Michowski, Wojciech; Wong, Michael; Gygli, Patrick Edwin; Gokozan, Hamza Numan; Griveau, Amélie; Odajima, Junko; Czeisler, Catherine; Catacutan, Fay Patsy; Murnen, Alice; Schüler, Ulrich; Sicinski, Piotr; Rowitch, David

    2014-01-01

    The mammalian genome encodes two A-type cyclins, which are considered potentially redundant yet essential regulators of the cell cycle. Here, we tested requirements for cyclin A1 and cyclin A2 function in cerebellar development. Compound conditional loss of cyclin A1/A2 in neural progenitors resulted in severe cerebellar hypoplasia, decreased proliferation of cerebellar granule neuron progenitors (CGNP), and Purkinje (PC) neuron dyslamination. Deletion of cyclin A2 alone showed an identical phenotype, demonstrating that cyclin A1 does not compensate for cyclin A2 loss in neural progenitors. Cyclin A2 loss lead to increased apoptosis at early embryonic time points but not at post-natal time points. In contrast, neural progenitors of the VZ/SVZ did not undergo increased apoptosis, indicating that VZ/SVZ-derived and rhombic lip-derived progenitor cells show differential requirements to cyclin A2. Conditional knockout of cyclin A2 or the SHH proliferative target Nmyc in CGNP also resulted in PC neuron dyslamination. Although cyclin E1 has been reported to compensate for cyclin A2 function in fibroblasts and is upregulated in cyclin A2 null cerebella, cyclin E1 expression was unable to compensate for loss-of cyclin A2 function. PMID:24184637

  1. Differentiating cerebellar and brainstem lesions with ocular vestibular-evoked myogenic potential test.

    PubMed

    Su, Chia-Hung; Young, Yi-Ho

    2011-06-01

    This study applied both ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) tests in patients with cerebellar disorders to determine whether VEMP test can differentiate between cerebellar and brainstem lesions. A total of 12 patients with cerebellar disorder, including extended cerebellar lesion (involving the brainstem) in 8 and localized cerebellar lesion (excluding the brainstem) in 4, were enrolled in this study. All patients underwent caloric, visual suppression, and oVEMP and cVEMP tests via bone-conducted vibration stimuli. The abnormal rates for the caloric, visual suppression, and oVEMP and cVEMP tests were 62, 83, 88 and 75% in patients with extended cerebellar lesion and 0, 25, 0 and 0% in those with localized cerebellar lesion, respectively. The rate of abnormal oVEMP results significantly differed between the two groups, but caloric, visual suppression and cVEMP test results did not differ. In another ten healthy subjects, characteristic parameters of oVEMPs obtained under light and dark conditions did not significantly differ. In conclusion, ocular VEMP test can differentiate between cerebellar and brainstem lesions. Abnormal oVEMPs in patients with cerebellar disorder may indicate adjacent brainstem involvement. PMID:21170655

  2. 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

  3. Entry, Descent, and Landing for Human Mars Missions

    NASA Technical Reports Server (NTRS)

    Munk, Michelle M.; DwyerCianciolo, Alicia M.

    2012-01-01

    One of the most challenging aspects of a human mission to Mars is landing safely on the Martian surface. Mars has such low atmospheric density that decelerating large masses (tens of metric tons) requires methods that have not yet been demonstrated, and are not yet planned in future Mars missions. To identify the most promising options for Mars entry, descent, and landing, and to plan development of the needed technologies, NASA's Human Architecture Team (HAT) has refined candidate methods for emplacing needed elements of the human Mars exploration architecture (such as ascent vehicles and habitats) on the Mars surface. This paper explains the detailed, optimized simulations that have been developed to define the mass needed at Mars arrival to accomplish the entry, descent, and landing functions. Based on previous work, technology options for hypersonic deceleration include rigid, mid-L/D (lift-to-drag ratio) aeroshells, and inflatable aerodynamic decelerators (IADs). The hypersonic IADs, or HIADs, are about 20% less massive than the rigid vehicles, but both have their technology development challenges. For the supersonic regime, supersonic retropropulsion (SRP) is an attractive option, since a propulsive stage must be carried for terminal descent and can be ignited at higher speeds. The use of SRP eliminates the need for an additional deceleration system, but SRP is at a low Technology Readiness Level (TRL) in that the interacting plumes are not well-characterized, and their effect on vehicle stability has not been studied, to date. These architecture-level assessments have been used to define the key performance parameters and a technology development strategy for achieving the challenging mission of landing large payloads on Mars.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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 was 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.

  9. 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.

  10. 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.

  11. Discrimination of 'driver' and 'passenger' HPV in tonsillar carcinomas by the polymerase chain reaction, chromogenic in situ hybridization, and p16(INK4a) immunohistochemistry.

    PubMed

    Evans, Mark Francis; Matthews, Alisa; Kandil, Dina; Adamson, Christine Stewart-Crawford; Trotman, Winifred Elizabeth; Cooper, Kumarasen

    2011-12-01

    Human papillomavirus (HPV) positive tonsillar squamous cell carcinoma (TSCC) is associated with a favorable clinical outcome. However, the HPV detected in a given tumor may be causal (driver HPV) or an incidental bystander (passenger HPV). There is a need to discriminate these forms of HPV in TSCCs to understand their impact on HPV as a biomarker for use in TSCC patient management. This study has compared the polymerase chain reaction (PCR), chromogenic in situ hybridization (CISH), and p16(INK4a) immunohistochemistry in the assessment of HPV status in TSCC. Archival specimens of TSCC from thirty patients were investigated. HPV was detected by PCR in 25/30 (83.3%) tumors; HPV16 (70.0%) and HPV52 (6.7%) were the most common types. HPV was corroborated by CISH in 22/25 (88.0%) specimens; integrated HPV was implicated by the presence of punctate signals in each of these cases. p16(INK4a) staining was found in 20/22 (90.9%) HPV PCR positive samples; two PCR/CISH HPV positive cases were p16(INK4a) negative and two HPV negative samples were p16(INK4a) positive. These data suggest that a minority of HPV positive TSCCs are positive for passenger HPV and that two or more assays may be required for diagnosing driver HPV status. Further studies are required to exam whether oropharyngeal tumors positive for passenger HPV have a less favorable prognosis than tumors that are driver HPV positive. The clinical significance of TSCCs that test HPV negative/p16(INK4a) positive, PCR and CISH HPV positive/p16 (INK4a) negative, or PCR HPV positive/p16 (INK4a) and CISH negative, also requires further investigation. PMID:21786153

  12. Frequent hepatocyte growth factor overexpression and low frequency of c-Met gene amplification in human papillomavirus-negative tonsillar squamous cell carcinoma and their prognostic significances.

    PubMed

    Kwon, Mi Jung; Kim, Dong Hoon; Park, Hye-Rim; Shin, Hyung Sik; Kwon, Ji Hyun; Lee, Dong Jin; Kim, Jin Hwan; Cho, Seong Jin; Nam, Eun Sook

    2014-07-01

    Human papillomavirus (HPV) is an important prognostic factor for tonsillar squamous cell carcinoma (TSCC). HPV-positive and HPV-negative TSCCs are considered distinct in terms of prognosis and sensitivity to chemo/radiotherapy. However, to date, no study has thoroughly evaluated the individual prognostic factors for these 2 disease subgroups. Hepatocyte growth factor (HGF)-Met signaling pathway can be a predictive marker for prognosis or therapy response, especially in HPV-negative TSCC. We therefore investigated the prognostic values of HGF and c-Met expression in TSCC according to HPV status. Immunohistochemical analyses of HGF and c-Met protein expression and silver in situ hybridization of c-Met gene copy number were performed in 79 formalin-fixed, paraffin-embedded specimens. In HPV-negative TSCC, HGF overexpression, regional lymph node category, and ipsilateral cervical nodal metastasis predicted decreased overall survival (OS) (P = .017, P = .024, and P = .003, respectively). The latter 2 were also independent prognostic factors for progression-free survival (P = .023 and P = .002, respectively). In HPV-positive TSCC, heavy alcohol consumption and advanced primary tumor category were predictive of progression-free survival, whereas no independent prognostic factor for OS was identified. HGF overexpression had a significant effect on OS in HPV-negative TSCC but not in HPV-positive TSCC. HPV-negative/HGF-high expression tumors exhibited the worst survival outcomes, whereas HPV-positive/HGF-low expression tumors had the most favorable prognosis. c-Met expression and c-Met gene amplification were not associated with survival outcomes in TSCC patients. In conclusion, HGF may be a potential prognostic marker in HPV-negative TSCC, whereas c-Met exhibited limited clinical significance in TSCC. PMID:24810547

  13. Reduced Number of CD8+ Cells in Tonsillar Germinal Centres in Children with the Periodic Fever, Aphthous Stomatitis, Pharyngitis and Cervical Adenitis Syndrome.

    PubMed

    Førsvoll, J; Janssen, E A M; Møller, I; Wathne, N; Skaland, I; Klos, J; Kristoffersen, E K; Øymar, K

    2015-07-01

    The syndrome of periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis (PFAPA) is an autoinflammatory disorder of unknown aetiology. Tonsillectomy may cause a prompt resolution of the syndrome. The aim was to study the histologic and immunological aspects of the palatine tonsils in PFAPA, to help understand the pathophysiology of the syndrome. Tonsils from children with PFAPA (n = 11) and children with tonsillar hypertrophy (n = 16) were evaluated histologically after haematoxylin and eosin staining. The number of different cell types was identified immunohistochemically by cluster of differentiation (CD) markers: CD3 (T cells), CD4 (T helper cells), CD8 (cytotoxic T cells), CD15 (neutrophils), CD20 (B cells), CD45 (all leucocytes), CD57 (NK cells) and CD163 (monocytes and macrophages). Tonsils from children with PFAPA showed reactive lymphoid hyperplasia dominated by well-developed germinal centres with many tingible body macrophages. The histologic findings were unspecific, and a similar morphologic appearance was also found in the tonsils from controls. The number of CD8+ cells in germinal centres differed between children with PFAPA [median 9 cells (quartiles: 5, 15)] and controls [18 cells (12, 33) (P = 0.001)] and between children with PFAPA with (median 14 cells; 9, 16) and without (4 cells; 3, 8) aphthous stomatitis (P = 0.015). For the other cell types, no differences in germinal centres were found between children with PFAPA and controls. In conclusion, a lower number of CD8+ cells were found in germinal centres of tonsils in children with PFAPA compared to controls, which may be a feature linked to the aetiology of the syndrome. PMID:25882211

  14. Fast Descent Methods for LPs With No Matrix Inversions Katta G. Murty

    E-print Network

    Murty, Katta G.

    Fast Descent Methods for LPs With No Matrix Inversions Katta G. Murty Department of IOE, University Programming (LP), Interior point methods (IPMs) , ball centers of a polytope, solving LPs by descent methods. It needed the solution of LPs in real time on GPUs ("Graphical Processing Units", the hot new topic in high

  15. Fast Descent Methods for LPs With No Matrix Inversions Katta G. Murty

    E-print Network

    Murty, Katta G.

    Fast Descent Methods for LPs With No Matrix Inversions Katta G. Murty Department of IOE, University of a polytope, solving LPs by descent methods without using matrix inversions. In Memorium: We dedicate is the graphics application posed by Watson [2010] recently. It needed the solution of LPs in real time on GPUs

  16. Algorithmic Operations Research Vol.7 (2013) 5154 Fast Descent Methods for LPs With No Matrix Inversions

    E-print Network

    Murty, Katta G.

    2013-01-01

    Algorithmic Operations Research Vol.7 (2013) 51­54 Fast Descent Methods for LPs With No Matrix. Key words: Linear Programming (LP), Interior point methods (IPMs) , solving LPs by descent methods to develop fast algorithms for LP without using matrix inversion operations. SMs consider LPs in the form

  17. ENUMERATION OF PARTITIONS BY RISES, LEVELS AND DESCENTS Toufik Mansour and Augustine O. Munagi

    E-print Network

    Breuer, Florian

    ENUMERATION OF PARTITIONS BY RISES, LEVELS AND DESCENTS Toufik Mansour and Augustine O. Munagi of integers, we study this statistic among the set partitions, as well as the numbers of rises and levels. We the statistics of numbers of rises, levels and descents among set partitions expressed as canonical sequences

  18. 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.

  19. Ethnic Identity and Acculturative Stress as Mediators of Depression in Students of Asian Descent

    ERIC Educational Resources Information Center

    Lantrip, Crystal; Mazzetti, Francesco; Grasso, Joseph; Gill, Sara; Miller, Janna; Haner, Morgynn; Rude, Stephanie; Awad, Germine

    2015-01-01

    This study underscored the importance of addressing the well-being of college students of Asian descent, because these students had higher rates of depression and lower positive feelings about their ethnic group compared with students of European descent, as measured by the Affirmation subscale of the Ethnic Identity Scale. Affirmation mediated…

  20. Lossless Convexification of Powered-Descent Guidance with Non-Convex Thrust Bound and Pointing Constraints

    E-print Network

    Williams, Brian C.

    -efficient, convex formulation of PDG (Powered-Descent Guidance) for Mars pinpoint and pre- cision landing has been-of-view requirements during landing. I. INTRODUCTION A typical Mars EDL (Entry, Descent and Landing) consists of a hypersonic entry phase, a parachute phase and a landing phase. The landing phase typically implements either

  1. The Role of la Familia for Women of Mexican Descent Who Are Leaders in Higher Education

    ERIC Educational Resources Information Center

    Elizondo, Sandra Gray

    2012-01-01

    The purpose of this qualitative case study was to describe the role of "la familia" for women of Mexican descent as it relates to their development as leaders and their leadership in academia. Purposeful sampling was utilized to reach the goal of 18 participants who were female academic leaders of Mexican descent teaching full time in…

  2. 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.

  3. Analysis of AIRE Continuous Descent Arrival operations at Atlanta and Miami

    Microsoft Academic Search

    Kevin R. Sprong; Kathryn A. Klein; C. Shiotsuki; J. Arrighi; S. Liu

    2008-01-01

    A continuous descent arrival (CDA) is a cockpit based flight technique characterized by operations that descend continuously at or near idle power settings resulting in reduced noise and emissions compared to standard stair-step arrival techniques. The development of published optimized profile descent (OPD) procedures that permit use of the CDA technique is generally considered to be a key step in

  4. Chart of Galileo's atmospheric probe entry/descent events at Jupiter

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Chart titled GALILEO ENTRY/DESCENT EVENTS traces the atmospheric probe of the Galileo spacecraft into Jupiter's atmosphere. Entry/descent events are charted from pre-entry to completion of reference mission with altitude (vertical axis) and time (horizontal axis) indicated.

  5. 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,

  6. Changes in a cerebellar peduncle lesion in a patient with Dandy-Walker malformation: A diffusion tensor imaging study?

    PubMed Central

    Lee, Ah Young; Jang, Sung Ho; Yeo, Sang Seok; Lee, Ensil; Cho, Yun Woo; Son, Su Min

    2013-01-01

    We report a patient with severe ataxia due to Dandy-Walker malformation, who showed functional recovery over 10 months corresponding to a change in a cerebellar peduncle lesion. A 20-month-old female patient who was diagnosed with Dandy-Walker syndrome and six age- and sex-matched healthy control subjects were enrolled. The superior cerebellar peduncle, the middle cerebellar peduncle, and the inferior cerebellar peduncle were evaluated using fractional anisotropy and the apparent diffusion coefficient. The patients’ functional ambulation category was 0 at the initial visit, but improved to 2 at the follow-up evaluation, and Berg's balance scale score also improved from 0 to 7. Initial diffusion tensor tractography revealed that the inferior cerebellar peduncle was not detected, that the fractional anisotropy of the superior cerebellar peduncle and middle cerebellar peduncle decreased by two standard deviations below, and that the apparent diffusion coefficient increased by two standard deviations over normal control values. However, on follow-up diffusion tensor tractography, both inferior cerebellar peduncles could be detected, and the fractional anisotropy of superior cerebellar peduncle increased to within two standard deviations of normal controls. The functional improvement in this patient appeared to correspond to changes in these cerebellar peduncles. We believe that evaluating cerebellar peduncles using diffusion tensor imaging is useful in cases when a cerebellar peduncle lesion is suspected. PMID:25206690

  7. Transient mutism following a posterior fossa approach to cerebellar tumors in children: a critical review of the literature

    Microsoft Academic Search

    Paulo Henrique Aguiar; José Pindaro P. Plese; Orildo Ciquini; Raul Marino

    1995-01-01

    Transient mutism has been known as a rare complication following a posterior fossa approach to cerebellar tumors and its cause has not been clearly elucidated. The cerebellar mutism is not accompanied by cranial nerve deficits and disorders of consciousness. Since 1985 only 23 cases of mutism following removal of a cerebellar tumor in children have been reported in the literature.

  8. Glutamate Neurotransmission in the Cerebellar Interposed Nuclei: Involvement in Classically Conditioned Eyeblinks and Neuronal Activity

    E-print Network

    Bracha, Vlastislav

    and on cerebellar nuclear neuronal activity were examined. Surpris- ingly, blocking fast glutamate receptors, identical amounts of DGG applied to the cerebellar cortex abolished CRs. Similar to the behavioral effects, DGG had unexpect- edly mild effects on IN neurons. At the population level, the baseline firing

  9. Children and adolescents with chronic cerebellar lesions show no clinically relevant signs of aphasia or neglect.

    PubMed

    Richter, S; Schoch, B; Kaiser, O; Groetschel, H; Hein-Kropp, C; Maschke, M; Dimitrova, A; Gizewski, E; Ziegler, W; Karnath, H-O; Timmann, D

    2005-12-01

    We studied language and visuospatial functions of 12 children and adolescents who had undergone surgery for cerebellar astrocytoma without subsequent radiation or chemotherapy and compared them with 27 age-, gender-, and education-matched healthy control subjects. To study possible lateralization of the functions of the left and right cerebellar hemispheres, subjects performed several language tasks including a verb-generation task as well as standard neglect and extinction tests. Three-dimensional-MR images confirmed that lesions affected cerebellar hemispheres in all children but one who had a pure vermal lesion. The right cerebellar hemisphere was affected in six, the left hemisphere in four children, and both hemispheres in one child. There were no signs of aphasia in the children or adolescents with cerebellar lesions. Language abilities did not differ between cerebellar patients and control subjects except for small increases in reaction times in verb generation in patients with left-sided lesions. Visuospatial functions were also intact in cerebellar subjects except for minor group differences in neglect tasks. In sum, chronic focal cerebellar lesions acquired in childhood or youth do not result in persistent language disorders or clinically significant signs of spatial neglect or extinction. PMID:16033937

  10. Lissencephaly associated with cerebellar hypoplasia and myoclonic epilepsy in a Bedouin kindred: a new syndrome?

    PubMed

    Farah, S; Sabry, M A; Khuraibet, A; Khaffagi, S; Rudwan, M; Hassan, M; Haseeb, N; Abulhassan, S; Abdel-Rasool, M A; Elgamal, S; Qasrawi, B; Al-Busairi, W; Farag, T I

    1997-05-01

    Clinico-radiological assessment of three mentally retarded members of a large Bedouin kindred showed lissencephaly, spastic paraparesis, myoclonic epilepsy and cerebellar hypoplasia. It seems that the familial association of lissencephaly/myoclonic epilepsy/cerebellar hypoplasia represents a new entity. PMID:9212181

  11. The cerebellar model of neural grafting: Structural integration and functional recovery

    Microsoft Academic Search

    Lazaros C. Triarhou

    1996-01-01

    A synopsis is presented of the recent history of cerebellar tissue transplantation over the past 25 years. The properties of growth and differentiation of cerebellar grafts placed intraocularly or intracranially are reviewed, as well as the interaction of heterotopic and orthotopic grafts with the host brain. Particular emphasis is placed on the use of ataxic mouse mutants as recipients of

  12. 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.…

  13. 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…

  14. Nuclear Factor I and Cerebellar Granule Neuron Development: An IntrinsicExtrinsic Interplay

    E-print Network

    Gronostajski, Richard M.

    Nuclear Factor I and Cerebellar Granule Neuron Development: An Intrinsic­Extrinsic Interplay Daniel, LLC 2010 Abstract Granule neurons have a central role in cerebellar function via their synaptic interactions with other neuronal cell types both within and outside this structure. Establish- ment

  15. Alcohol Enhances GABAergic Transmission to Cerebellar Granule Cells via an Increase in Golgi Cell Excitability

    Microsoft Academic Search

    Mario Carta; Manuel Mameli; C. Fernando

    2004-01-01

    Alcohol intoxication alters coordination and motor skills, and this is responsible for a significant number of traffic accident-related deaths around the world. Although the precise mechanism of action of ethanol (EtOH) is presently unknown, studies suggest that it acts, in part, by interfering with normal cerebellar functioning. An important component of cerebellar circuits is the granule cell. The excit- ability

  16. 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

  17. Cerebellar arachnoid cyst in a firesetter: the weight of organic lesions in arson.

    PubMed Central

    Heidrich, A; Schmidtke, A; Lesch, K P; Hofmann, E; Becker, T

    1996-01-01

    A 52-year-old female patient was accused of arson; the patient had had an arachnoid cyst of the cerebellar vermis. Even after surgery, she showed marked instability of mood and pseudologia fantastica, but did not suffer from cognitive impairment. Possible associations of the presence of this cerebellar arachnoid cyst and behavioral disturbances are discussed. Images Figure 1 Figure 2 PMID:8935333

  18. Diffusion Tensor Tractography of the Human Brain Cortico-Ponto-Cerebellar Pathways: A Quantitative Preliminary Study

    PubMed Central

    Kamali, Arash; Kramer, Larry A.; Frye, Richard E.; Butler, Ian J; Hasan, Khader M.

    2015-01-01

    Purpose To investigate the utility of diffusion tensor tractography at 1mm slice thickness to map and quantify the whole trajectory of different cortico-ponto-cerebellar pathways of the healthy adult human brain. Materials and Methods This work was approved by the local Institutional Review Board, and was Health Insurance Portability and Accountability Act (HIPAA) compliant. Five healthy right-handed men (age range, 24–37 years) were studied and written informed consent was obtained. Diffusion tensor imaging data acquired with 1-mm slice thickness at a 3.0 Tesla (T) clinical MRI scanner were prepared and analyzed using tractography methods to reconstruct the cortico-ponto-cerebellar pathways which included the fronto-ponto-cerebellar, parieto-ponto-cerebellar, occipitoponto- cerebellar, and temporo-ponto-cerebellar tracts. Results We demonstrate the feasibility of tractographic mapping and quantification of the four cortico-ponto-cerebellar system components based on their cortical connections in the healthy human brain using DTI data with thin 1-mm sections. Conclusion In vivo quantification of different corticoponto-cerebellar pathways based on cortical connection is feasible, using 1-mm slices at 3.0T. PMID:20882611

  19. Spatial and Temporal Sequence Learning in Patients with Parkinson's Disease or Cerebellar Lesions

    E-print Network

    Ivry, Rich

    Spatial and Temporal Sequence Learning in Patients with Parkinson's Disease or Cerebellar Lesions in sequence learning is not clear. In the current study, Parkinson's patients, patients with cerebellar damage between the two patient groups. Whereas the Parkinson's patients learned the spatial and temporal

  20. Diagnostic Approach to Childhood-onset Cerebellar Atrophy: A 10-Year Retrospective Study of 300 Patients

    PubMed Central

    Al-Maawali, Almundher; Blaser, Susan; Yoon, Grace

    2013-01-01

    Hereditary ataxias associated with cerebellar atrophy are a heterogeneous group of disorders. Selection of appropriate clinical and genetic tests for patients with cerebellar atrophy poses a diagnostic challenge. Neuroimaging is a crucial initial investigation in the diagnostic evaluation of ataxia in childhood, and the presence of cerebellar atrophy helps guide further investigations. We performed a detailed review of 300 patients with confirmed cerebellar atrophy on magnetic resonance imaging over a 10-year period. A diagnosis was established in 47% of patients: Mitochondrial disorders were most common, followed by the neuronal ceroid lipofuscinoses, ataxia telangectasia, and late GM2-gangliosidosis. We review the common causes of cerebellar atrophy in childhood and propose a diagnostic approach based on correlating specific neuroimaging patterns with clinical and genetic diagnoses. PMID:22764178

  1. Diagnostic approach to childhood-onset cerebellar atrophy: a 10-year retrospective study of 300 patients.

    PubMed

    Al-Maawali, Almundher; Blaser, Susan; Yoon, Grace

    2012-09-01

    Hereditary ataxias associated with cerebellar atrophy are a heterogeneous group of disorders. Selection of appropriate clinical and genetic tests for patients with cerebellar atrophy poses a diagnostic challenge. Neuroimaging is a crucial initial investigation in the diagnostic evaluation of ataxia in childhood, and the presence of cerebellar atrophy helps guide further investigations. We performed a detailed review of 300 patients with confirmed cerebellar atrophy on magnetic resonance imaging over a 10-year period. A diagnosis was established in 47% of patients: Mitochondrial disorders were most common, followed by neuronal ceroid lipofuscinosis, ataxia telangiectasia, and late-onset GM2 gangliosidosis. We review the common causes of cerebellar atrophy in childhood and propose a diagnostic approach based on correlating specific neuroimaging patterns with clinical and genetic diagnoses. PMID:22764178

  2. The Role of Intermittent Hypoxia on the Proliferative Inhibition of Rat Cerebellar Astrocytes

    PubMed Central

    Chiu, Sheng-Chun; Lin, Yu-Jou; Huang, Sung-Ying; Lien, Chih-Feng; Chen, Shee-Ping; Pang, Cheng-Yoong; Lin, Jian-Hong; Yang, Kun-Ta

    2015-01-01

    Sleep apnea syndrome, characterized by intermittent hypoxia (IH), is linked with increased oxidative stress. This study investigates the mechanisms underlying IH and the effects of IH-induced oxidative stress on cerebellar astrocytes. Rat primary cerebellar astrocytes were kept in an incubator with an oscillating O2 concentration between 20% and 5% every 30 min for 1–4 days. Although the cell loss increased with the duration, the IH incubation didn’t induce apoptosis or necrosis, but rather a G0/G1 cell cycle arrest of cerebellar astrocytes was noted. ROS accumulation was associated with cell loss during IH. PARP activation, resulting in p21 activation and cyclin D1 degradation was associated with cell cycle G0/G1 arrest of IH-treated cerebellar astrocytes. Our results suggest that IH induces cell loss by enhancing oxidative stress, PARP activation and cell cycle G0/G1 arrest in rat primary cerebellar astrocytes. PMID:26172116

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

    PubMed

    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. PMID:25852520

  4. Hereditary lissencephaly and cerebellar hypoplasia in Churra lambs

    PubMed Central

    2013-01-01

    Background Lissencephaly is a rare developmental brain disorder in veterinary and human medicine associated with defects in neuronal migration leading to a characteristic marked reduction or absence of the convolutional pattern of the cerebral hemispheres. In many human cases the disease has a genetic basis. In sheep, brain malformations, mainly cerebellar hypoplasia and forms of hydrocephalus, are frequently due to in utero viral infections. Although breed-related malformations of the brain have been described in sheep, breed-related lissencephaly has not been previously recorded in a peer reviewed publication. Results Here we report neuropathological findings in 42 newborn lambs from a pure Churra breed flock, with clinical signs of weakness, inability to walk, difficulty in sucking and muscular rigidity observed immediately after birth. All the lambs showed near-total agyria with only a rudimentary formation of few sulci and gyri, and a severe cerebellar hypoplasia. On coronal section, the cerebral grey matter was markedly thicker than that of age-matched unaffected lambs and the ventricular system was moderately dilated. Histologically, the normal layers of the cerebral cortex were disorganized and, using an immunohistochemical technique against neurofilaments, three layers were identified instead of the six present in normal brains. The hippocampus was also markedly disorganised and the number and size of lobules were reduced in the cerebellum. Heterotopic neurons were present in different areas of the white matter. The remainder of the brain structures appeared normal. The pathological features reported are consistent with the type LCH-b (lissencephaly with cerebellar hypoplasia group b) defined in human medicine. No involvement of pestivirus or bluetongue virus was detected by immunohistochemistry. An analysis of pedigree data was consistent with a monogenic autosomal recessive pattern inheritance. Conclusions The study describes the clinical and pathological findings of lissencephaly with cerebellar hypoplasia in Churra lambs for which an autosomal recessive inheritance was the most likely cause. Histopathological features observed in the cerebral cortex and hippocampus are consistent with a possible failure in neuronal migration during brain development. This report suggests that lissencephaly should be considered in the differential diagnosis of congenital neurological disease in newborn lambs showing weakness, inability to walk and difficulty sucking. PMID:23938146

  5. Cerebellar Model Controller Applied in Wind Power Prediction

    NASA Astrophysics Data System (ADS)

    Shao, Yichuan; Yao, Xingjia

    Wind Power prediction is very important in the wind power grid management. This paper introduces how to use Cerebellar Model Articulation Controller(CMAC) to build a short-term wind power prediction model.CMAC and Back-propagation Artificial Neural Networks(BP) are used respectively to do the short-term prediction with the data from a wind farm in Inner Mongolia. After comparison of the results, CMAC is more stable, accurate and faster than BP neural network with less training data.. CMAC is considered to be more suitable to do the short-term prediction.

  6. Endoscopic evacuation of cerebellar hematoma in a term newborn.

    PubMed

    Tanriverdi, Sema Rala; Turhan, Tuncer; Uygur, Ozgun; Koroglu, Ozge Altun; Yalaz, Mehmet; Kultursay, Nilgun

    2013-10-01

    Intracerebellar hemorrhage is very rare in term infants and only severe cases with massive intracranial hemorrhage, posthemorrhagic hydrocephalus and clinical deterioration due to increased intracranial pressure require neurosurgical evacuation. In recent adult studies endoscopic hematoma evacuation has been shown as a rapid, effective, and safe technique. A term newborn hospitalized for meconium aspiration syndrome showed hypertonia, jitteriness and abnormal amplitude integrated electroencephalogram findings. He was diagnosed with cerebellar hematoma which caused hydrocephalus by cranial magnetic resonance imaging (MRI). The hematoma was successfully evacuated neuroendoscopically as the first case in literature to our knowledge. Neurologic, a-EEG and MRI findings resolved. PMID:23265617

  7. Application of a simple cerebellar model to geologic surface mapping

    USGS Publications Warehouse

    Hagens, A.; Doveton, J.H.

    1991-01-01

    Neurophysiological research into the structure and function of the cerebellum has inspired computational models that simulate information processing associated with coordination and motor movement. The cerebellar model arithmetic computer (CMAC) has a design structure which makes it readily applicable as an automated mapping device that "senses" a surface, based on a sample of discrete observations of surface elevation. The model operates as an iterative learning process, where cell weights are continuously modified by feedback to improve surface representation. The storage requirements are substantially less than those of a conventional memory allocation, and the model is extended easily to mapping in multidimensional space, where the memory savings are even greater. ?? 1991.

  8. Schistosomiasis mansoni presenting as a cerebellar tumor: case report.

    PubMed

    Silva, Joacil Carlos da; Lima, Frederico de Melo Tavares de; Vidal, Cláudio Henrique; Azevedo Filho, Hildo Cirne Rocha de

    2007-09-01

    The Manson's schistosomiasis tumoral form rarely affects the brain. There are only 12 cases prior related with a mean age of 25 years and a male predominance. We describe a 16-year-old Brazilian Northeastern boy with a cerebellar mass lesion. The radiological aspect was considered compatible with glioma and a gross total resection was performed. Microscopic examination disclosed intraparenchymal granulomas surrounding Schistosoma mansoni eggs. The case is compared with the literature findings and some peculiar aspects of this trematode infection are reviewed. PMID:17952294

  9. Intrameatal aneurysm of the anterior inferior cerebellar artery.

    PubMed

    Zotta, Donato C; Stati, Giovanni; De Paulis, Danilo; Galzio, Renato J

    2011-04-01

    Aneurysms of the distal part of the anterior-inferior cerebellar artery (AICA) are rare, with an incidence of 0.1% to 0.5%. We report a 55-year-old woman suffering from a subarachnoid hemorrhage resulting from a ruptured intrameatal aneurysm of the AICA. A left retrosigmoid craniotomy was performed and the aneurysm was clipped without post-operative deficits. Follow-up angiography demonstrated exclusion of the aneurysm, confirming preservation of the distal AICA. We review the pertinent literature and discuss clinical presentation, radiological findings and surgical management of this patient. PMID:21257312

  10. 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.

  11. Cerebellar abnormalities in Huntington's disease: a role in motor and psychiatric impairment?

    PubMed

    Rees, Elin M; Farmer, Ruth; Cole, James H; Haider, Salman; Durr, Alexandra; Landwehrmeyer, Bernhard; Scahill, Rachael I; Tabrizi, Sarah J; Hobbs, Nicola Z

    2014-11-01

    The cerebellum has received limited attention in Huntington's disease (HD), despite signs of possible cerebellar dysfunction, including motor incoordination and impaired gait, which are currently attributed to basal ganglia atrophy and disrupted fronto-striatal circuits. This study is the first to investigate a potential contribution of macro- and microstructural cerebellar damage to clinical manifestations of HD. T1- and diffusion-weighted 3T magnetic resonance imaging (MRI) scans were obtained from 12 controls and 22 early-stage HD participants. Manual delineation and voxel-based morphometry were used to assess between-group differences in cerebellar volume, and diffusion metrics were compared between groups within the cerebellar gray and white matter. Associations between these imaging measures and clinical scores were examined within the HD group. Reduced paravermal volume was detected in HD compared with controls using voxel-based morphometry (P?cerebellar gray matter and white matter. Smaller cerebellar volumes, although not significantly reduced, were significantly associated with impaired gait and psychiatric morbidity and of borderline significance with pronate/supinate-hand task performance. Abnormal cerebellar diffusion was associated with increased total motor score, impaired saccade initiation, tandem walking, and timed finger tapping. In conclusion, atrophy of the paravermis, possibly encompassing the cerebellar nuclei, and microstructural abnormalities within the cerebellum may contribute to HD neuropathology. Aberrant cerebellar diffusion and reduced cerebellar volume together associate with impaired motor function and increased psychiatric symptoms in stage I HD, potentially implicating the cerebellum more centrally in HD presentation than previously recognized. PMID:25123926

  12. 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

  13. Discrete Mathematics and Theoretical Computer Science DMTCS vol. 10:3, 2008, 122 Counting descents, rises, and levels, with

    E-print Network

    Paris-Sud XI, Université de

    , rises, and levels, with prescribed first element, in words Sergey Kitaev1 and Toufik Mansour2 and Jeff of descents, levels, and rises according to whether the first letter of the descent, rise, or level lies in Ni some of the results by Burstein and Mansour. Keywords: descent, level, rise, set partition, word

  14. 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.

  15. Dynamic Cerebrospinal Fluid Flow on MRI in Cortical Cerebellar Atrophy and Multiple System Atrophy-cerebellar Type.

    PubMed

    Fukui, Yusuke; Hishikawa, Nozomi; Sato, Kota; Kono, Syoichiro; Matsuzono, Kosuke; Nakano, Yumiko; Ohta, Yasuyuki; Yamashita, Toru; Deguchi, Kentaro; Abe, Koji

    2015-01-01

    Objective The purpose of this study was to examine a new MRI technology, dynamic cerebrospinal fluid (CSF) flow, to examine sporadic cerebellar ataxia patients with cortical cerebellar atrophy (CCA) and multiple system atrophy-cerebellar type (MSA-C). Methods Nine CCA patients (3 men and 6 women; mean age: 64.2±6.9 years) and 31 MSA-C patients (13 men and 18 women; mean age: 62.7±6.8 years) were examined by a dynamic CSF flow analysis. All CSF flow data were evaluated by phase contrast-MRI using a 1.5T MRI scanner. The CSF flow was calculated by 15 images in the equidistant MRI sequence which was taken through a cardiac cycle. Results Compared with the CCA patients, the absolute values of the mean velocity of the MSA-C patients were significantly reduced at time points 5 (CCA, 0.24±0.14 cm/s; MSA-C, 0.13±0.11 cm/s; (*) p<0.05) and 13 (CCA, -0.60±0.37 cm/s; MSA-C, -0.31±0.17 cm/s; (**) p<0.01). Significant correlations in Spearman's rank correlation coefficient were also found in MSA-C patients between the disease duration and the difference between the maximum and minimum velocities (Vheight) (r=-0.429, (*) p<0.05), the minimum velocity of the CSF (Vmin) (r=0.486, (**) p<0.01) or the length of the minor axis of the pons (r=-0.529, (**) p<0.01). The linear regressions between the disease duration and Vheight or Vmin revealed a significant strong correlation only in the MSA-C patients. Conclusion The present CSF flow study showed for the first time that Vheight and Vmin revealed good correlations with the disease duration in the MSA-C patients. Furthermore, the velocity of the prepontine CSF flow tended to decrease in the MSA-C patients compared with the CCA patients, suggesting that this particular CSF flow analysis may be a new surrogate marker for differentiating both types of cerebellar ataxia. PMID:26179524

  16. Mars Exploration Rovers Entry, Descent, and Landing Trajectory Analysis

    NASA Technical Reports Server (NTRS)

    Desai, Prasun N.; Knocke, Philip C.

    2004-01-01

    The Mars Exploration Rover mission successfully landed two rovers "Spirit" and "Opportunity" on Mars on January 4th and 25th of 2004, respectively. The trajectory analysis performed to define the entry, descent, and landing (EDL) scenario is described. The entry requirements and constraints are presented, as well as uncertainties used in a Monte Carlo dispersion analysis to statistically assess the robustness of the entry design to off-nominal conditions. In the analysis, six-degree-of-freedom and three-degree-of-freedom trajectory results are compared to assess the entry characteristics of the capsule. Comparison of the preentry results to preliminary post-landing reconstruction data shows that all EDL parameters were within the requirements. In addition, the final landing position for both "Spirit" and "Opportunity" were within 15 km of the predicted landing location.

  17. Mars Exploration Rover: Launch, Cruise, Entry, Descent, and Landing

    NASA Technical Reports Server (NTRS)

    Erickson, James K.; Manning, Robert M.; Adler, M.

    2004-01-01

    The Mars Exploration Rover Project was an ambitious effort to land two highly capable rovers on Mars and concurrently explore the Martian surface for three months each. Launched in June and July of 2003, cruise operations were conducted through January 4, 2004 with the first landing, followed by the second landing on January 25. The prime mission for the second rover ended on April 27, 2004. This paper will provide an overview of the launch, cruise, and landing phases of the mission, including the engineering and science objectives and challenges involved in the selection and targeting of the landing sites, as well as the excitement and challenges of atmospheric entry, descent and landing execution.

  18. A guidance law for hypersonic descent to a point

    SciTech Connect

    Eisler, G.R. [Sandia National Labs., Albuquerque, NM (United States); Hull, D.G. [Texas Univ., Austin, TX (United States)

    1992-05-01

    A neighboring external control problem is formulated for a hypersonic glider to execute a maximum-terminal-velocity descent to a stationary target. The resulting two-part, feedback control scheme initially solves a nonlinear algebraic problem to generate a nominal trajectory to the target altitude. Secondly, a neighboring optimal path computation about the nominal provides a lift and side-force perturbations necessary to achieve the target downrange and crossrange. On-line feedback simulations of the proposed scheme and a form of proportional navigation are compared with an off-line parameter optimization method. The neighboring optimal terminal velocity compares very well with the parameter optimization solution and is far superior to proportional navigation. 8 refs.

  19. A guidance law for hypersonic descent to a point

    SciTech Connect

    Eisler, G.R. (Sandia National Labs., Albuquerque, NM (United States)); Hull, D.G. (Texas Univ., Austin, TX (United States))

    1992-01-01

    A neighboring external control problem is formulated for a hypersonic glider to execute a maximum-terminal-velocity descent to a stationary target. The resulting two-part, feedback control scheme initially solves a nonlinear algebraic problem to generate a nominal trajectory to the target altitude. Secondly, a neighboring optimal path computation about the nominal provides a lift and side-force perturbations necessary to achieve the target downrange and crossrange. On-line feedback simulations of the proposed scheme and a form of proportional navigation are compared with an off-line parameter optimization method. The neighboring optimal terminal velocity compares very well with the parameter optimization solution and is far superior to proportional navigation. 8 refs.

  20. Analysis of Atmospheric Mesoscale Models for Entry, Descent and Landing

    NASA Technical Reports Server (NTRS)

    Kass, D. M.; Schofield, J. T.; Michaels, T. I.; Rafkin, S. C. R.; Richardson, M. I.; Toigo, A. D.

    2003-01-01

    Each Mars Exploration Rover (MER) is sensitive to the martian winds encountered near the surface during the Entry, Descent and Landing (EDL) process. These winds are strongly influenced by local (mesoscale) conditions. In the absence of suitable wind observations, wind fields predicted by martian mesoscale atmospheric models have been analyzed to guide landing site selection. Two different models were used, the MRAMS model and the Mars MM5 model. In order to encompass both models and render their results useful to the EDL engineering team, a series of statistical techniques were applied to the model results. These analyses cover the high priority landing sites during the expected landing times (1200 to 1500 local time). The number of sites studied is limited by the computational and analysis cost of the mesoscale models.

  1. Adapting Mars Entry, Descent and Landing System for Earth

    NASA Astrophysics Data System (ADS)

    Heilimo, J.; Harri, A.-M.; Aleksashkin, S.; Koryanov, V.; Guerrero, H.; Schmidt, W.; Haukka, H.; Finchenko, V.; Martynov, M.; Ostresko, B.; Ponomarenko, A.; Kazakovtsev, V.; Arruego, I.; Martin, S.; Siili, T.

    2013-09-01

    In 2001 - 2011 an inflatable Entry, Descent and Landing System (EDLS) for Martian atmosphere was developed by FMI and the MetNet team. This MetNet Mars Lander EDLS is used in both the initial deceleration during atmospheric entry and in the final deceleration before the semi-hard impact of the penetrator to Martian surface. The EDLS design is ingenious and its applicability to Earth's atmosphere is studied in the on-going project. In particular, the behavior of the system in the critical transonic aerodynamic (from hypersonic to subsonic) regime will be investigated. This project targets to analyze and test the transonic behavior of this compact and light weight payload entry system to Earth's atmosphere [1]. Scaling and adaptation for terrestrial atmospheric conditions, instead of a completely new design, is a favorable approach for providing a new re-entry vehicle for terrestrial space applications.

  2. Adapting Mars Entry, Descent and Landing System for Earth

    NASA Astrophysics Data System (ADS)

    Heilimo, J.; Harri, A.-M.; Alexashkin, S.; Koryanov, V.; Guerrero, H.; Schmidt, W.; Haukka, H.; Finchenko, V.; Martynov, M.; Ostresko, B.; Ponomarenko, A.; Kazakovtsev, V.; Martin, S.; Siili, T.

    2012-09-01

    In 2001 - 2011 an inflatable Entry, Descent and Landing System (EDLS) for Martian atmosphere was developed by FMI and the MetNet team. This MetNet Mars Lander EDLS is used in both the initial deceleration during atmospheric entry and in the final deceleration before the semi-hard impact of the penetrator to Martian surface. The EDLS design is ingenious and its applicability to Earth's atmosphere is studied in the on-going project. In particular, the behaviour of the system in the critical transonic aerodynamic (from hypersonic to subsonic) regime will be investigated. This project targets to analyse and test the transonic behaviour of this compact and light weight payload entry system to Earth's atmosphere. Scaling and adaptation for terrestrial atmospheric conditions, instead of a completely new design, is a favourable approach for providing a new re-entry vehicle for terrestrial space applications.

  3. Cerebellar-Dependent Eyeblink Conditioning Deficits in Schizophrenia Spectrum Disorders

    PubMed Central

    Forsyth, Jennifer K.; Bolbecker, Amanda R.; Mehta, Crystal S.; Klaunig, Mallory J.; Steinmetz, Joseph E.; O'Donnell, Brian F.; Hetrick, William P.

    2012-01-01

    Accumulating evidence suggests that abnormalities in neural circuitry and timing associated with the cerebellum may play a role in the pathophysiology of schizophrenia. Schizotypal personality disorder (SPD) may be genetically linked to schizophrenia, but individuals with SPD are freer from potential research confounds and may therefore offer insight into psychophysiological correlates of schizophrenia. The present study employed a delay eyeblink conditioning (EBC) procedure to examine cerebellar-dependent learning in schizophrenia, SPD, and healthy control subjects (n = 18 per group) who were matched for age and gender. The conditioned stimulus was a 400-ms tone that coterminated with a 50 ms unconditioned stimulus air puff. Cognitive performance on the Picture Completion, Digit Symbol Coding, Similarities, and Digit Span subscales of the Wechsler Adult Intelligence Scale—Third Edition was also investigated. The schizophrenia and SPD groups demonstrated robust EBC impairment relative to the control subjects; they had significantly fewer conditioned responses (CRs), as well as smaller CR amplitudes. Schizophrenia subjects showed cognitive impairment across subscales compared with SPD and control subjects; SPD subjects showed intermediate performance to schizophrenia and control subjects and performed significantly worse than controls on Picture Completion. Impaired EBC was significantly related to decreased processing speed in schizophrenia spectrum subjects. These findings support the role of altered cortico-cerebellar-thalamic-cortical circuitry in the pathophysiology of schizophrenia spectrum disorders. PMID:21148238

  4. Biosensor measurement of purine release from cerebellar cultures and slices

    PubMed Central

    Eason, Robert; Dale, Nicholas

    2010-01-01

    We have previously described an action-potential and Ca2+-dependent form of adenosine release in the molecular layer of cerebellar slices. The most likely source of the adenosine is the parallel fibres, the axons of granule cells. Using microelectrode biosensors, we have therefore investigated whether cultured granule cells (from postnatal day 7–8 rats) can release adenosine. Although no purine release could be detected in response to focal electrical stimulation, purine (adenosine, inosine or hypoxanthine) release occurred in response to an increase in extracellular K+ concentration from 3 to 25 mM coupled with addition of 1 mM glutamate. The mechanism of purine release was transport from the cytoplasm via an ENT transporter. This process did not require action-potential firing but was Ca2+dependent. The major purine released was not adenosine, but was either inosine or hypoxanthine. In order for inosine/hypoxanthine release to occur, cultures had to contain both granule cells and glial cells; neither cellular component was sufficient alone. Using the same stimulus in cerebellar slices (postnatal day 7–25), it was possible to release purines. The release however was not blocked by ENT blockers and there was a shift in the Ca2+ dependence during development. This data from cultures and slices further illustrates the complexities of purine release, which is dependent on cellular composition and developmental stage. PMID:21103217

  5. 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

  6. Deep Learning for Cerebellar Ataxia Classification and Functional Score Regression

    PubMed Central

    Yang, Zhen; Zhong, Shenghua; Carass, Aaron; Ying, Sarah H.; Prince, Jerry L.

    2014-01-01

    Cerebellar ataxia is a progressive neuro-degenerative disease that has multiple genetic versions, each with a characteristic pattern of anatomical degeneration that yields distinctive motor and cognitive problems. Studying this pattern of degeneration can help with the diagnosis of disease subtypes, evaluation of disease stage, and treatment planning. In this work, we propose a learning framework using MR image data for discriminating a set of cerebellar ataxia types and predicting a disease related functional score. We address the difficulty in analyzing high-dimensional image data with limited training subjects by: 1) training weak classifiers/regressors on a set of image subdomains separately, and combining the weak classifier/regressor outputs to make the decision; 2) perturbing the image subdomain to increase the training samples; 3) using a deep learning technique called the stacked auto-encoder to develop highly representative feature vectors of the input data. Experiments show that our approach can reliably classify between one of four categories (healthy control and three types of ataxia), and predict the functional staging score for ataxia. PMID:25553339

  7. Speech prosody in Friedreich's and olivo-ponto cerebellar atrophy

    NASA Astrophysics Data System (ADS)

    Casper, Maureen

    2001-05-01

    A critical issue in the study of speech motor control is the identification of the mechanisms that generate the temporal flow of serially ordered articulatory events. Two staged models of serial ordered events (Lashley, 1951; Lindblom, 1963) claim that time controls events whereas dynamic models predict a relative relation between time and space. Each of these models predicts a different relation between the acoustic measures of formant frequency and segmental duration. The most recent method described herein provides a sensitive index of speech deterioration which is both acoustically robust and phonetically systematic. Both acoustic and magnetic resonance imaging measures were used to describe the speech disturbance in two neurologically distinct groups of cerebellar ataxia: Friedreich's ataxia and olivo-ponto cerebellar ataxia. The speaking task was designed to elicit six different prosodic conditions and four prosodic contrasts. All subjects read the same syllable embedded in a sentence, under six different prosodic conditions. Pair-wise comparisons derived from the six conditions were used to describe (1) final lengthening, (2) phrasal accent, (3) nuclear accent and (4) syllable reduction. An estimate of speech deterioration as determined by individual and normal subects' acoustic values of syllable duration, formant and fundamental frequencies was used in correlation analyses with magnetic resonance imaging ratings.

  8. 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

  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. Cortico-cerebellar abnormalities in adolescents with heavy marijuana use.

    PubMed

    Lopez-Larson, Melissa P; Rogowska, Jadwiga; Bogorodzki, Piotr; Bueler, Charles Elliott; McGlade, Erin C; Yurgelun-Todd, Deborah A

    2012-06-30

    There are currently no studies that have evaluated the motor network, including the cerebellum, in adolescent marijuana (MJ) smokers. The current study aimed to evaluate whether there were activation differences in Brodmann's area 4 (BA4), Brodmann's area 6 (BA6), cingulate (CG) and cerebellum between MJ-using adolescents and healthy controls (HC) on a functional magnetic resonance imaging (fMRI) bilateral finger-tapping task. Twenty-four adolescents (aged 18.2 ± 0.7 years) with heavy MJ use and 24 HC (18.0 ± 1.9) had MRI scans on a 3T Siemens scanner, including a standard bilateral fMRI finger-tapping sequence. Imaging data were analyzed using SPM5 in Matlab. As regions of interest, BA4, BA6, cingulate (CG) and cerebellum were selected, and significant clusters of activity were thresholded at p<0.05, corrected. Healthy controls had significantly greater activation than MJ users for the CG and cerebellum. In addition, activation of the cerebellum and CG correlated with lifetime MJ smokes. This is one of the first studies to evaluate cortico-cerebellar circuits in adolescents with heavy MJ use. The study, which used a bilateral finger-tapping fMRI task, provides evidence for both CG and cerebellar dysfunction in MJ abuse and indicates that lifetime MJ use may impact the developing brain. PMID:22835865

  11. Transcranial cerebellar direct current stimulation (tcDCS): motor control, cognition, learning and emotions.

    PubMed

    Ferrucci, Roberta; Priori, Alberto

    2014-01-15

    The neurological manifestations of cerebellar diseases range from motor to cognitive or behavioral abnormalities. Experimental data in healthy subjects extend the cerebellar role to learning, emotional and mood control. The need for a non-invasive tool to influence cerebellar function in normal and pathological conditions led researchers to develop transcranial cerebellar direct current stimulation (tcDCS). tcDCS, like tDCS, depends on the principle that weak direct currents delivered at around 2mA for minutes over the cerebellum through surface electrodes induce prolonged changes in cerebellar function. tcDCS modulates several cerebellar skills in humans including motor control, learning and emotional processing. tcDCS also influences the cerebello-brain interactions induced by transcranial magnetic stimulation (TMS), walking adaptation, working memory and emotional recognition. Hence tcDCS is a simple physiological tool that can improve our physiological understanding of the human cerebellum, and should prove useful also in patients with cerebellar dysfunction or psychiatric disorders and those undergoing neurorehabilitation to enhance neuroplasticity. PMID:23664951

  12. 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

  13. Cerebellar Morphology and the Effects of Stimulant Medications in Youths with Attention Deficit-Hyperactivity Disorder

    PubMed Central

    Ivanov, Iliyan; Murrough, James W; Bansal, Ravi; Hao, Xuejun; Peterson, Bradley S

    2014-01-01

    The cerebellum is emerging as a key anatomical structure underlying normal attentional and cognitive control mechanisms. Dysregulation within cerebellar circuits may contribute to the core symptoms of Attention Deficit/Hyperactivity Disorder (ADHD). In the present study we aimed to characterize surface morphological features of the cerebellum in ADHD and healthy comparison youths. Further, we studied the association of cerebellar morphology with the severity of ADHD symptoms and the effects of stimulant treatment. We examined 46 youths with ADHD and 59 comparison youths 8–18 years of age in a cross-sectional, case–control study using magnetic resonance imaging. Measures of cerebellar surface morphology were the primary outcome. Relative to comparison participants, youths with ADHD exhibited smaller regional volumes corresponding to the lateral surface of the left anterior and the right posterior cerebellar hemispheres. Stimulant medication was associated with larger regional volumes over the left cerebellar surface, whereas more severe ADHD symptoms were associated with smaller regional volumes in the vermis. We used optimized measures of morphology to detect alterations in cerebellar anatomy specific to ADHD, dimensions of symptomology, and stimulant treatment. Duration of treatment correlated positively with volumes of specific cerebellar subregions, supporting a model whereby compensatory morphological changes support the effects of stimulant treatment. PMID:24077064

  14. Recurrent audiovestibular disturbance initially mimicking Ménière's disease in a patient with anterior inferior cerebellar infarction.

    PubMed

    Park, Jong-Ho; Kim, Hyeyun; Han, Hyun-Jeong

    2008-10-01

    An anterior inferior cerebellar artery (AICA) stroke is characterized by vertigo, tinnitus, and deafness in addition to facial weakness, hemiataxia, and hypalgesia. Sometimes, it can present as sudden deafness with vertigo, without brainstem or cerebellar signs. We report a 55-year-old woman with hypertension and diabetes, showing recurrent audiovestibular disturbance before a typical pattern of AICA infarction, which was initially diagnosed as Ménière's disease. In elderly patients with recurrent hearing loss and vertigo lasting several minutes, lack classic brainstem or cerebellar signs, if they have vascular risk factors, physicians may also consider the potential symptom of AICA infarction. PMID:18941941

  15. Cerebellar abnormalities typical of methylmercury poisoning in a fledged saltmarsh sparrow, Ammodramus caudacutus.

    PubMed

    Scoville, Sheila A; Lane, Oksana P

    2013-05-01

    A fledged, 12-15 day-old saltmarsh sparrow, Ammodramus caudacutus, was collected from an accidental kill on Cinder Island, Long Island, NY, USA. The sparrow was assessed for feather mercury levels and the brain analyzed for cerebellar abnormalities by microscopic examination. In humans, fetal Minamata disease is caused by maternal ingestion of mercury. It is characterized by disrupted and disordered cerebellar neuronal migration in the fetus or infant. Results from this sparrow show cerebellar abnormalities typical of Minamata disease. It is the first known avian or mammalian specimen taken from the wild to show the abnormalities typical of the human fetal syndrome. PMID:23478946

  16. Insights From Cerebellar Transcriptomic Analysis Into the Pathogenesis of Ataxia

    PubMed Central

    Bettencourt, Conceição; Ryten, Mina; Forabosco, Paola; Schorge, Stephanie; Hersheson, Joshua; Hardy, John; Houlden, Henry

    2015-01-01

    IMPORTANCE The core clinical and neuropathological feature of the autosomal dominant spinocerebellar ataxias (SCAs) is cerebellar degeneration. Mutations in the known genes explain only 50% to 60% of SCA cases. To date, no effective treatments exist, and the knowledge of drug-treatable molecular pathways is limited. The examination of overlapping mechanisms and the interpretation of how ataxia genes interact will be important in the discovery of potential disease-modifying agents. OBJECTIVES To address the possible relationships among known SCA genes, predict their functions, identify overlapping pathways, and provide a framework for candidate gene discovery using whole-transcriptome expression data. DESIGN, SETTING, AND PARTICIPANTS We have used a systems biology approach based on whole-transcriptome gene expression analysis. As part of the United Kingdom Brain Expression Consortium, we analyzed the expression profile of 788 brain samples obtained from 101 neuropathologically healthy individuals (10 distinct brain regions each). Weighted gene coexpression network analysis was used to cluster 24 SCA genes into gene coexpression modules in an unsupervised manner. The overrepresentation of SCA transcripts in modules identified in the cerebellum was assessed. Enrichment analysis was performed to infer the functions and molecular pathways of genes in biologically relevant modules. MAIN OUTCOMES AND MEASURES Molecular functions and mechanisms implicating SCA genes, as well as lists of relevant coexpressed genes as potential candidates for novel SCA causative or modifier genes. RESULTS Two cerebellar gene coexpression modules were statistically enriched in SCA transcripts (P = .021 for the tan module and P = 2.87 × 10?5 for the light yellow module) and contained established granule and Purkinje cell markers, respectively. One module includes genes involved in the ubiquitin-proteasome system and contains SCA genes usually associated with a complex phenotype, while the other module encloses many genes important for calcium homeostasis and signaling and contains SCA genes associated mostly with pure ataxia. CONCLUSIONS AND RELEVANCE Using normal gene expression in the human brain, we identified significant cell types and pathways in SCA pathogenesis. The overrepresentation of genes involved in calcium homeostasis and signaling may indicate an important target for therapy in the future. Furthermore, the gene networks provide new candidate genes for ataxias or novel genes that may be critical for cerebellar function. PMID:24862029

  17. Entry, Descent, and Landing Communications for the 2007 Phoenix Mars Lander

    NASA Technical Reports Server (NTRS)

    Kornfeld, Richard P.; Garcia, Mark D.; Craig, Lynn E.; Butman, Stan; Signori, Gina M.

    2008-01-01

    This paper addresses NASA's requirement on the 2007 Phoenix Mars Lander to provide spacecraft communications during entry, descent, and landing on Mars to allow the identification of probable root cause should any mission failure occur. The Phoenix mission launched on 4 August 2007 and will land on 25 May 2008 on the northern plains of Mars to conduct a three-month study of the Martian environment. The paper discusses the architectural trades in designing a communications link and surveys the entry, descent, and landing communications approaches taken by previous missions. It then discusses the Phoenix-specific constraints and degrees of freedoms and presents a novel and robust implementation approach to entry, descent, and landing communications. The overall methodology and conclusions described herein can serve as a pathfinder for the entry, descent, and landing communications architecture and implementation of future Mars landed missions.

  18. 2007 Mars Phoenix Entry, Descent, and Landing Simulation and Modeling Analysis

    NASA Technical Reports Server (NTRS)

    Prince, Jill L.; Grover, Myron R.; Desai, Prasun N.; Queen, Eric M.

    2007-01-01

    This viewgraph presentation reviews the entry, descent, and landing of the 2007 Mars Phoenix lander. Aerodynamics characteristics along with Monte Carlo analyses are also presented for launch and landing site opportunities.

  19. Stochastic Gradient Descent for Non-smooth Optimization: Convergence Results and Optimal Averaging Schemes

    E-print Network

    Zhang, Tong

    , Atlanta, Georgia, USA, 2013. Copyright 2013 by the author(s)/owner(s). Stochastic Gradient Descent (SGD Tong Zhang tzhang@stat.rutgers.edu Department of Statistics, Rutgers University, Piscataway NJ 08854

  20. Recent identity by descent in human genetic data - methods and applications 

    E-print Network

    Glodzik, Dominik

    2014-11-28

    The thesis describes algorithms for detecting regions of recent identity by descent (IBD) from human genetic data and its applications in optimising resequencing studies, genomic predictions and detecting Mendelian ...

  1. 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

  2. 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

  3. 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.

  4. DSENDS -A High-Fidelity Dynamics and Spacecraft Simulator for Entry, Descent and Surface Landing12

    E-print Network

    missions. We first briefly describe the core tool capabilities in dynamics, instrument/actuator device/navigation simulation modules for hypersonic steering and powered descent. Models for landing kinematics and dynamics

  5. Fabrication Assembly and Test of the Mars Science Laboratory Descent Stage Propulsion System

    NASA Technical Reports Server (NTRS)

    Parker, Morgan; Baker, Ray; Casillas, Art; Strommen, Dellon; Tanimoto, Rebekah

    2013-01-01

    The Descent Stage Propulsion System (DSPS) is the most challenging and complex propulsion system ever built at JPL. Performance requirements, such as the entry Reaction Control System (RCS) requirements, and the terminal descent requirements (3300 N maximum thrust and approximately 835,000 N-s total impulse in less than a minute), required a large amount of propellant and a large number of components for a spacecraft that had to fit in a 4.5 meter aeroshell. The size and shape of the aeroshell, along with the envelope of the stowed rover, limited the configuration options for the Descent Stage structure. The configuration and mass constraints of the Descent Stage structure, along with performance requirements, drove the configuration of the DSPS. This paper will examine some of the challenges encountered and solutions developed during the fabrication, assembly, and test of the DSPS.

  6. Challenges of Dealing With Atmospheres: Entry, Descent and Landing - Duration: 31 seconds.

    NASA Video Gallery

    Whether landing on Mars or returning to Earth, one of the most challenging parts of any mission is the entry, descent and landing. Just think -- a spacecraft hurtling through space at thousands of ...

  7. Autosomal recessive spino-olivo-cerebellar degeneration without ataxia.

    PubMed Central

    Staal, A; Stefanko, S Z; Jennekens, F G; Vries-Bos, L H; van Gijn, J

    1983-01-01

    Five adult siblings from a sibship of ten suffering from an external ophthalmoplegia with a spastic paraplegia are reported. In addition, optic nerve atrophy was present in three of the patients and dementia in two; extrapyramidal signs and cerebellar ataxia were found only in one patient. Contrary to earlier studies of patients with comparable neurological signs the pattern of inheritance was autosomal recessive. Neuropathological investigation of the index case, who had never shown ataxia, nevertheless showed demyelination of the spinocerebellar and the olivocerebellar pathways, and also a severe loss of Purkinje cells, of cells in Clarke's column and in the inferior olives. The dentate nucleus was severely gliotic but showed no cell loss. Earlier neuropathological investigations of this disorder, but with an autosomal dominant heredity, were incomplete. It is concluded that the five siblings of this family have a unique autosomal recessive disorder, which should be considered a distinct entity. Images PMID:6886703

  8. 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

  9. Upper limb cerebellar motor function in children with spina bifida

    PubMed Central

    Jewell, Derryn; Fletcher, Jack M.; Mahy, Caitlin E. V.; Hetherington, Ross; MacGregor, Daune; Drake, James M.; Salman, Michael S.

    2011-01-01

    Purpose To investigate upper limb cerebellar motor function in children with spina bifida myelomeningocele (SBM) and in typically developing controls. Methods Participants with SBM, who had either upper level spinal lesions (n=23) or lower level spinal lesions (n=65), and controls (n=37) completed four upper limb motor function tasks (posture, rebound, limb dysmetria, and diadochokinesis) under four different physical and cognitive challenge conditions. Functional independence was assessed by parental questionnaire. Results Fewer SBM participants were able to complete the posture task, and they were less likely than controls to obtain a perfect rebound score. Participants with SBM showed impaired performance in either time, accuracy, or both, on the limb dysmetria and diadochokinesis tasks but responded like controls to physical and cognitive challenges. Conclusions Because upper limb motor performance predicted aspects of functional independence, we conclude that upper limb impairments in children with SBM are significant and have direct implications for the level of independent functioning in children with SBM. PMID:19823846

  10. The cerebellar nodulus: perceptual and ocular processing of graviceptive input.

    PubMed

    Tarnutzer, Alexander A; Wichmann, Werner; Straumann, Dominik; Bockisch, Christopher J

    2015-02-01

    Current concepts postulate a decisive role of the cerebellar nodulus in the processing of otolith input. We hypothesized that nodular lesions abolish otolith-perceptual integration, predicting alignment of perceived direction of earth vertical with the z-axis of the head and not with gravity. In an 80-year-old patient with acute heminodular infarction, the subjective visual vertical deviated contralesionally by -21.1° when the patient was upright. After subtracting this offset, perceived vertical closely matched the patient's head orientation when the patient was roll-tilted. Otolith-ocular reflexes remained normal. This is the first report on abolished earth verticality perception in heminodular stroke and underlines the importance of the nodulus in spatial orientation. PMID:25515599

  11. [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

  12. A simple method for estimating minimum autorotative descent rate of single rotor helicopters

    NASA Technical Reports Server (NTRS)

    Talbot, P. D.; Schroers, L. G.

    1978-01-01

    Flight test results of minimum autorotative descent rate are compared with calculations based on the minimum power required for steady level flight. Empirical correction factors are derived that account for differences in energy dissipation between these two flight conditions. A method is also presented for estimating the minimum power coefficient for level flight for any helicopter for use in the empirical estimation procedure of autorotative descent rate.

  13. 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.

  14. Glaucoma detection: the content of optometric eye examinations for a presbyopic patient of African racial descent

    Microsoft Academic Search

    R Shah; D F Edgar; P G Spry; R A Harper; A Kotecha; S Rughani; B J W Evans

    2009-01-01

    Aims:Standardised patient (SP) methodology is the gold standard for evaluating clinical practice. We investigated the content of optometric eyecare for an early presbyopic SP of African racial descent, an “at-risk” patient group for primary open-angle glaucoma (POAG).Methods:A trained actor presented unannounced as a 44-year-old patient of African racial descent, complaining of recent near vision difficulties, to 100 community optometrists for

  15. Mars Science Laboratory Entry, Descent and Landing System Development Challenges and Preliminary Flight Performance

    NASA Technical Reports Server (NTRS)

    Steltzner, Adam D.; San Martin, A. Miguel; Rivellini, Tommaso P.

    2013-01-01

    The Mars Science Laboratory project recently landed the Curiosity rover on the surface of Mars. With the success of the landing system, the performance envelope of entry, descent, and landing capabilities has been extended over the previous state of the art. This paper will present an overview of the MSL entry, descent, and landing system, a discussion of a subset of its development challenges, and include a discussion of preliminary results of the flight reconstruction effort.

  16. Steepest Descent Trajectories on Isosurfaces of the Scalar Field and of Fluctuations of the Scalar Curvature

    NASA Astrophysics Data System (ADS)

    Lasukov, V. V.; Moldovanova, E. A.; Il'kin, E. E.; Novoselov, V. V.; Rozhkova, S. V.; Rozhkova, O. V.

    2015-05-01

    It has been shown that steepest descent trajectories on an isosurface of the scalar field or of fluctuations of the scalar curvature can serve as the geometric skeleton of galaxies, these trajectories simultaneously being isolines of the isosurface. Isolines and isosurfaces can generate matter via the mechanism of spontaneous emission of the Lemaître-Friedmann primordial atom. Steepest descent trajectories on an isosurface of fluctuations of the scalar curvature can also serve as the skeleton of quantum inhomogeneities of the density in GTR.

  17. 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.

  18. 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

  19. Improved Cerebellar Tissue Classification on Magnetic Resonance Images of Brain

    PubMed Central

    Datta, Sushmita; Tao, Guozhi; He, Renjie; Wolinsky, Jerry S.; Narayana, Ponnada A.

    2009-01-01

    Purpose To develop and implement a method for improved cerebellar tissue classification on the magnetic resonance images of brain by automatically isolating the cerebellum prior to segmentation. Materials and Methods Dual fast spin echo (FSE) and fluid attenuation inversion recovery (FLAIR) images were acquired on eighteen normal volunteers on a 3 T Philips scanner. The cerebellum was isolated from rest of the brain by using a symmetric inverse consistent nonlinear registration of individual brain with the parcellated template. The cerebellum was then separated by masking the anatomical image with individual FLAIR images. Tissues in both the cerebellum and rest of the brain were separately classified using hidden Markov random field (HMRF), a parametric method, and then combined to obtain tissue classification of the whole brain. The proposed method for tissue classification on real magnetic resonance (MR) brain images was evaluated subjectively by two experts. The segmentation results on Brainweb images with varying noise and intensity nonuniformity levels were quantitatively compared with the ground truth by computing the Dice similarity indices. Results The proposed method has significantly improved the cerebellar tissue classification on all normal volunteers included in this study without compromising the classification in remaining part of the brain. The average similarity indices for gray matter (GM) and white matter (WM) in the cerebellum are 89.81 (± 2.34) and 93.04 (± 2.41), demonstrating excellent performance of the proposed methodology. Conclusion The proposed method significantly improved tissue classification in the cerebellum. The GM was overestimated when segmentation was performed on the whole brain as a single object. PMID:19388122

  20. Dicer Is Required for Normal Cerebellar Development and to Restrain Medulloblastoma Formation

    PubMed Central

    Zindy, Frederique; Lee, Youngsoo; Kawauchi, Daisuke; Ayrault, Olivier; Merzoug, Leila Ben; Li, Yang; McKinnon, Peter J.; Roussel, Martine F.

    2015-01-01

    Dicer, a ribonuclease III enzyme, is required for the maturation of microRNAs. To assess its role in cerebellar and medulloblastoma development, we genetically deleted Dicer in Nestin-positive neural progenitors and in mice lacking one copy for the Sonic Hedgehog receptor, Patched 1. We found that conditional loss of Dicer in mouse neural progenitors induced massive Trp53-independent apoptosis in all proliferative zones of the brain and decreased proliferation of cerebellar granule progenitors at embryonic day 15.5 leading to abnormal cerebellar development and perinatal lethality. Loss of one copy of Dicer significantly accelerated the formation of mouse medulloblastoma of the Sonic Hedgehog subgroup in Patched1-heterozygous mice. We conclude that Dicer is required for proper cerebellar development, and to restrain medulloblastoma formation. PMID:26091048

  1. A novel inhibitory nucleo-cortical circuit controls cerebellar Golgi cell activity.

    PubMed

    Ankri, Lea; Husson, Zoé; Pietrajtis, Katarzyna; Proville, Rémi; Léna, Clément; Yarom, Yosef; Dieudonné, Stéphane; Uusisaari, Marylka Yoe

    2015-01-01

    The cerebellum, a crucial center for motor coordination, is composed of a cortex and several nuclei. The main mode of interaction between these two parts is considered to be formed by the inhibitory control of the nuclei by cortical Purkinje neurons. We now amend this view by showing that inhibitory GABA-glycinergic neurons of the cerebellar nuclei (CN) project profusely into the cerebellar cortex, where they make synaptic contacts on a GABAergic subpopulation of cerebellar Golgi cells. These spontaneously firing Golgi cells are inhibited by optogenetic activation of the inhibitory nucleo-cortical fibers both in vitro and in vivo. Our data suggest that the CN may contribute to the functional recruitment of the cerebellar cortex by decreasing Golgi cell inhibition onto granule cells. PMID:25965178

  2. Verbal short-term memory and cerebellum: evidence from a patient with congenital cerebellar vermis hypoplasia.

    PubMed

    Misciagna, Sandro; Iuvone, Laura; Mariotti, Paolo; Silveri, Maria Caterina

    2010-04-01

    The impairment of phonological short-term memory has been reported in adults with cerebellar lesions. At the same time, a role of the cerebellum in speech production has been hypothesized. Cerebellar malformations have been related to developmental problems and language acquisition in children. We describe a 5-year-old male child with cerebellar vermis hypoplasia who presented a severe linguistic deficit. On language testing, verbal production was almost absent, while comprehension was partially spared. Digit span was markedly reduced. An extensive examination of phonological short-term memory confirmed a deficit at this level. Positron Emission Tomography revealed hypometabolism both in the cerebellum and the supratentorial areas involved in language function. This finding supports the hypothesis that the cerebellum is included in a cerebro-cerebellar network, that underlies the phonological short-term memory, whose integrity is necessary for language acquisition. PMID:19927261

  3. CNVanalysis locates ASD's pathogenesis in the cerebellar vermis Sepp Hochreiter, and DjorkArn Clevert

    E-print Network

    Hochreiter, Sepp

    CNVanalysis locates ASD's pathogenesis in the cerebellar vermis Sepp Hochreiter, and Djork investigated neurodevelopmental dysfunctions in autism spectrum disorder (ASD) by an integrative (CNA) and ASD, the BioGPS tissue atlas, the Allen brain atlas, and in situ hybridization

  4. A novel inhibitory nucleo-cortical circuit controls cerebellar Golgi cell activity

    PubMed Central

    Ankri, Lea; Husson, Zoé; Pietrajtis, Katarzyna; Proville, Rémi; Léna, Clément; Yarom, Yosef; Dieudonné, Stéphane; Uusisaari, Marylka Yoe

    2015-01-01

    The cerebellum, a crucial center for motor coordination, is composed of a cortex and several nuclei. The main mode of interaction between these two parts is considered to be formed by the inhibitory control of the nuclei by cortical Purkinje neurons. We now amend this view by showing that inhibitory GABA-glycinergic neurons of the cerebellar nuclei (CN) project profusely into the cerebellar cortex, where they make synaptic contacts on a GABAergic subpopulation of cerebellar Golgi cells. These spontaneously firing Golgi cells are inhibited by optogenetic activation of the inhibitory nucleo-cortical fibers both in vitro and in vivo. Our data suggest that the CN may contribute to the functional recruitment of the cerebellar cortex by decreasing Golgi cell inhibition onto granule cells. DOI: http://dx.doi.org/10.7554/eLife.06262.001 PMID:25965178

  5. The Huygens Probe Descent Trajectory Working Group: Organizational framework, goals, and implementation

    NASA Astrophysics Data System (ADS)

    Atkinson, David H.; Kazeminejad, Bobby; Lebreton, Jean-Pierre; Witasse, Olivier; Pérez-Ayúcar, Miguel; Matson, Dennis L.

    2007-11-01

    Cassini/Huygens, a flagship mission to explore the rings, atmosphere, magnetic field, and moons that make up the Saturn system, is a joint endeavor of the National Aeronautics and Space Administration, the European Space Agency, and Agenzia Spaziale Italiana. Comprising two spacecraft - a Saturn orbiter built by NASA and a Titan entry/descent probe built by the European Space Agency - Cassini/Huygens was launched in October 1997. The Huygens probe parachuted to the surface of Titan in January 2005. During the descent, six science instruments provided in situ measurements of Titan's atmosphere, clouds, and winds, and photographed Titan's surface. To correctly interpret and correlate results from the probe science experiments, and to provide a reference set of data for ground-truth calibration of orbiter remote sensing measurements, an accurate reconstruction of the probe entry and descent trajectory and surface landing location is necessary. The Huygens Descent Trajectory Working Group was chartered in 1996 as a subgroup of the Huygens Science Working Team to develop and implement an organizational framework and retrieval methodologies for the probe descent trajectory reconstruction from the entry altitude of 1270 km to the surface using navigation data, and engineering and science data acquired by the instruments on the Huygens Probe. This paper presents an overview of the Descent Trajectory Working Group, including the history, rationale, goals and objectives, organizational framework, rules and procedures, and implementation.

  6. Supervised descent method with low rank and sparsity constraints for robust face alignment

    NASA Astrophysics Data System (ADS)

    Sun, Yubao; Hu, Bin; Deng, Jiankang; Li, Xing

    2015-03-01

    Supervised Descent Method (SDM) learns the descent directions of nonlinear least square objective in a supervised manner, which has been efficiently used for face alignment. However, SDM still may fail in the cases of partial occlusions and serious pose variations. To deal with this issue, we present a new method for robust face alignment by utilizing the low rank prior of human face and enforcing sparse structure of the descent directions. Our approach consists of low rank face frontalization and sparse descent steps. Firstly, in terms of the low rank prior of face image, we recover such a low-rank face from its deformed image and the associated deformation despite significant distortion and corruption. Alignment of the recovered frontal face image is more simple and effective. Then, we propose a sparsity regularized supervised descent model by enforcing the sparse structure of the descent directions under the l1constraint, which makes the model more effective in computation and robust to partial occlusion. Extensive results on several benchmarks demonstrate that the proposed method is robust to facial occlusions and pose variations

  7. 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

  8. MRI Detection of the Cerebellar Syndrome in Creutzfeldt–Jakob Disease

    Microsoft Academic Search

    Oren S. Cohen; Chen Hoffmann; Hedok Lee; Joab Chapman; Robert K. Fulbright; Isak Prohovnik

    2009-01-01

    Creutzfeldt–Jakob Disease (CJD) is characterized by bilateral basal ganglia hyperintensities on T2W and diffusion-weighted\\u000a imaging (DWI) magnetic resonance imaging (MRI) scans, consistent with its extrapyramidal neurological manifestations. MRI\\u000a is diagnostically uninformative about the cerebellar symptoms, equally prominent in CJD. This study was undertaken to explain\\u000a this apparent paradox. Eleven CJD patients with definite cerebellar or brain stem symptoms were selected

  9. 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

  10. Ataxia associated with Hashimoto's disease: progressive non-familial adult onset cerebellar degeneration with autoimmune thyroiditis

    PubMed Central

    Selim, M; Drachman, D

    2001-01-01

    Acquired cerebellar ataxia has been described with hypothyroidism, and is typically reversible by thyroid hormone replacement therapy. The cerebellar dysfunction has been attributed to metabolic and physiological effects of the endocrine disorder. In a few patients, however, ataxia has persisted despite thyroid replacement therapy. Other mechanisms may be involved in ataxia associated with thyroid disorders.?OBJECTIVE—To document progressive non-familial adult onset cerebellar degeneration (PNACD) occurring in six patients with raised antithyroid antibodies (Hashimoto's/autoimmune thyroiditis), and other autoimmune manifestations, in the absence of hypothyroidism; and to document the independence of the cerebellar disorder from the endocrine dysfunction.?METHODS—A case study of six patients with PNACD reviewing the clinical course and relation to endocrine and autoimmune status.?RESULTS—All six patients were euthyroid when they developed their symptoms; had raised antithyroid antibodies consistent with Hashimoto's autoimmune thyroiditis; and had strong personal or family histories of organ specific autoimmune diatheses. Brain MRI disclosed atrophy of the cerebellar vermis in four patients and olivopontocerebellar atrophy in two. Other possible causes of cerebellar degeneration were excluded. De novo treatment (two patients) or continued treatment (three patients) with L-thyroxine did not modify the progression of the ataxia.?CONCLUSIONS—Cerebellar degeneration in these patients with raised antithyroid antibodies may be immune mediated. The presence of antithyroid antibodies may signal or cause the autoimmune process producing cerebellar degeneration. "Hashimoto's associated ataxia" seems to represent a recognisable and not uncommon condition; a trial of immunomodulating therapy should be considered in these patients.?? PMID:11413268

  11. Clinical-psychological characteristics of children with dysgenesis of the cerebellar vermis

    Microsoft Academic Search

    M. Yu. Bobylova; A. S. Petrukhin; G. N. Dunaevskaya; S. V. Piliya; E. S. Il’ina

    2007-01-01

    This report addresses behavioral abnormalities in children with cerebellar anomalies demonstrated on MRI scans. Published\\u000a data are presented showing an interaction between cerebellar pathology and early childhood autism. The cerebellum is involved\\u000a not only in movement coordination, but also in social adaptation and verbal communication. The genes expressed in the cerebellum\\u000a during childhood are identical to those expressed in the

  12. Expression of Cerebellar Long-Term Depression Requires Postsynaptic Clathrin-Mediated Endocytosis

    Microsoft Academic Search

    Yu Tian Wang; David J. Linden

    2000-01-01

    Cerebellar long-term depression (LTD) is a cellular model system of information storage that may underlie certain forms of motor learning. While cerebellar LTD is expressed as a selective modification of postsynaptic AMPA receptors, this might involve changes in receptor number\\/distribution, unitary conductance, kinetics, or glutamate affinity. The observation that GluR2-containing synaptic AMPA receptors could be internalized by regulated clathrin-mediated endocytosis

  13. Visuomotor adaptive improvement and aftereffects are impaired differentially following cerebellar lesions in SCA and PICA territory

    Microsoft Academic Search

    Susen Werner; Otmar Bock; Elke R. Gizewski; Beate Schoch; Dagmar Timmann

    2010-01-01

    The aim of the present study was to elucidate the contribution of the superior and posterior inferior cerebellum to adaptive\\u000a improvement and aftereffects in a visuomotor adaptation task. Nine patients with ischemic lesions within the territory of\\u000a the posterior inferior cerebellar artery (PICA), six patients with ischemic lesions within the territory of the superior cerebellar\\u000a artery (SCA) and 17 age-matched

  14. Holoprosencephaly with cerebellar vermis hypoplasia in 13q deletion syndrome: Critical region for cerebellar dysgenesis within 13q32.2q34.

    PubMed

    Mimaki, Masakazu; Shiihara, Takashi; Watanabe, Mio; Hirakata, Kyoko; Sakazume, Satoru; Ishiguro, Akio; Shimojima, Keiko; Yamamoto, Toshiyuki; Oka, Akira; Mizuguchi, Masashi

    2015-08-01

    We describe two unrelated patients with terminal deletions in the long arm of chromosome 13 showing brain malformation consisting of holoprosencephaly and cerebellar vermis hypoplasia. Array comparative genomic hybridization analysis revealed a pure terminal deletion of 13q31.3q34 in one patient and a mosaic ring chromosome with 13q32.2q34 deletion in the other. Mutations in ZIC2, located within region 13q32, cause holoprosencephaly, whereas the 13q32.2q32.3 region is associated with cerebellar vermis hypoplasia (Dandy-Walker syndrome). The rare concurrence of these major brain malformations in our patients provides further evidence that 13q32.2q32.3 deletion, harboring ZIC2 and ZIC5, leads to cerebellar dysgenesis. PMID:25454392

  15. Beaconless stochastic parallel gradient descent laser beam control: numerical experiments.

    PubMed

    Piatrou, Piotr; Roggemann, Michael

    2007-09-20

    We apply a target-in-the-loop strategy to the case of adaptive optics beam control in the presence of strong atmospheric turbulence for air-to-ground directed energy laser applications. Using numerical simulations we show that in the absence of a cooperative beacon to probe the atmosphere it is possible to extract information suitable for effective beam control from images of the speckled and strongly turbulence degraded intensity distribution of the laser energy at the target. We use a closed-loop, single-deformable-mirror adaptive optics system driven by a target-in-the-loop stochastic parallel gradient descent optimization algorithm minimizing a mean-radius performance metric defined on the image of the laser beam intensity distribution formed at the receiver. We show that a relatively low order 25-channel zonal adaptive optical beam control system controlled in this way is capable of achieving a high degree of turbulence compensation with respect to energy concentration if the tilt can be corrected separately. PMID:17882306

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. Development of a Mars Airplane Entry, Descent, and Flight Trajectory

    NASA Technical Reports Server (NTRS)

    Murray, James E.; Tartabini, Paul V.

    2001-01-01

    An entry, descent, and flight (EDF) trajectory profile for a Mars airplane mission is defined as consisting of the following elements: ballistic entry of an aeroshell; supersonic deployment of a decelerator parachute; subsonic release of a heat shield; release, unfolding, and orientation of an airplane to flight attitude; and execution of a pull up maneuver to achieve trimmed, horizontal flight. Using the Program to Optimize Simulated Trajectories (POST) a trajectory optimization problem was formulated. Model data representative of a specific Mars airplane configuration, current models of the Mars surface topography and atmosphere, and current estimates of the interplanetary trajectory, were incorporated into the analysis. The goal is to develop an EDF trajectory to maximize the surface-relative altitude of the airplane at the end of a pull up maneuver, while subject to the mission design constraints. The trajectory performance was evaluated for three potential mission sites and was found to be site-sensitive. The trajectory performance, examined for sensitivity to a number of design and constraint variables, was found to be most sensitive to airplane mass, aerodynamic performance characteristics, and the pull up Mach constraint. Based on the results of this sensitivity study, an airplane-drag optimized trajectory was developed that showed a significant performance improvement.

  1. STS-40 descent BET products: Development and results

    NASA Technical Reports Server (NTRS)

    Oakes, Kevin F.; Wood, James S.; Findlay, John T.

    1991-01-01

    Descent Best Estimate Trajectory (BET) Data were generated for the final Orbiter Experiments Flight, STS-40. This report discusses the actual development of these post-flight products: the inertial BET, the Extended BET, and the Aerodynamic BET. Summary results are also included. The inertial BET was determined based on processing Tracking and Data Relay Satellite (TDRSS) coherent Doppler data in conjunction with observations from eleven C-band stations, to include data from the Kwajalein Atoll and the usual California coastal radars, as well as data from five cinetheodolite cameras in the vicinity of the runways at EAFB. The anchor epoch utilized for the trajectory reconstruction was 53,904 Greenwich Mean Time (GMT) seconds which corresponds to an altitude at epoch of approximately 708 kft. Atmospheric data to enable development of an Extended BET for this mission were upsurped from the JSC operational post-flight BET. These data were evaluated based on Space Shuttle-derived considerations as well as model comparisons. The Aerodynamic BET includes configuration information, final mass properties, and both flight-determined and predicted aerodynamic performance estimates. The predicted data were based on the final pre-operational databook, updated to include flight determined incrementals based on an earlier ensemble of flights. Aerodynamic performance comparisons are presented and correlated versus statistical results based on twenty-two previous missions.

  2. Augmented cerebellar lactate in copper deficient rat pups originates from both blood and cerebellum

    PubMed Central

    Gybina, Anna A.; Prohaska, Joseph R.

    2010-01-01

    Copper (Cu) is essential for proper brain development, particularly the cerebellum, and functions as a cofactor for enzymes including mitochondrial cytochrome c oxidase (CCO). Cu deficiency severely limits CCO activity. Augmented lactate in brain of Cu deficient (Cu?) humans and cerebella of Cu? rats is though to originate from impaired mitochondria. However, brain lactate may also originate from elevated blood lactate. The hypothesis that cerebellar lactate originates from elevated blood lactate in Cu? rat pups was tested. Analysis of Cu? and Cu adequate (Cu+) rat pups (experiment I) revealed blood lactate was elevated in Cu? rat pups and cerebellar lactate levels were closely correlated to blood lactate concentration. A second rat experiment (experiment II) assessed Cu? cerebellar lactate without the confounding factor of elevated blood lactate. Blood lactate levels of Cu? rat pups in experiment II were equal to those of controls; however, Cu? cerebellar lactate was still elevated, suggesting mitochondrial impairment by Cu deficiency. Treatment of rat pups with dichloroacetate (DCA), an activator of mitochondrial pyruvate dehydrogenase complex (PDC), lowered Cu? cerebellar lactate to control levels suggesting PDC inhibition is a site of mitochondrial impairment in Cu? cerebella. Results suggest Cu? cerebellar lactate originates from blood and cerebellum. PMID:19319671

  3. Integrated plasticity at inhibitory and excitatory synapses in the cerebellar circuit.

    PubMed

    Mapelli, Lisa; Pagani, Martina; Garrido, Jesus A; D'Angelo, Egidio

    2015-01-01

    The way long-term potentiation (LTP) and depression (LTD) are integrated within the different synapses of brain neuronal circuits is poorly understood. In order to progress beyond the identification of specific molecular mechanisms, a system in which multiple forms of plasticity can be correlated with large-scale neural processing is required. In this paper we take as an example the cerebellar network, in which extensive investigations have revealed LTP and LTD at several excitatory and inhibitory synapses. Cerebellar LTP and LTD occur in all three main cerebellar subcircuits (granular layer, molecular layer, deep cerebellar nuclei) and correspondingly regulate the function of their three main neurons: granule cells (GrCs), Purkinje cells (PCs) and deep cerebellar nuclear (DCN) cells. All these neurons, in addition to be excited, are reached by feed-forward and feed-back inhibitory connections, in which LTP and LTD may either operate synergistically or homeostatically in order to control information flow through the circuit. Although the investigation of individual synaptic plasticities in vitro is essential to prove their existence and mechanisms, it is insufficient to generate a coherent view of their impact on network functioning in vivo. Recent computational models and cell-specific genetic mutations in mice are shedding light on how plasticity at multiple excitatory and inhibitory synapses might regulate neuronal activities in the cerebellar circuit and contribute to learning and memory and behavioral control. PMID:25999817

  4. Terra incognita—cerebellar contributions to neuropsychiatric and cognitive dysfunction in behavioral variant frontotemporal dementia

    PubMed Central

    Tan, Rachel H.; Devenney, Emma; Kiernan, Matthew C.; Halliday, Glenda M.; Hodges, John R.; Hornberger, Michael

    2015-01-01

    Although converging evidence has positioned the human cerebellum as an important relay for intact cognitive and neuropsychiatric processing, changes in this large structure remain mostly overlooked in behavioral variant frontotemporal dementia (bvFTD), a disease which is characterized by cognitive and neuropsychiatric deficits. The present study assessed whether degeneration in specific cerebellar subregions associate with indices of cognition and neuropsychiatric performance in bvFTD. Our results demonstrate a relationship between cognitive and neuropsychiatric decline across various domains of memory, language, emotion, executive, visuospatial function, and motivation and the degree of gray matter degeneration in cerebellar lobules V–VII. Most notably, bilateral cerebellar lobule VII and the posterior vermis emerged as distinct for memory processes, the right cerebellar hemisphere underpinned emotion, and the posterior vermis was highlighted in language dysfunction in bvFTD. Based on cortico-cerebellar connectivity maps, these findings in the cerebellum are consistent with the neural connections with the cortices involved in these domains in patients with bvFTD. Overall, the present study underscores the significance of cortical-cerebellar networks associated with cognition and neuropsychiatric dysfunction in bvFTD.

  5. 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

  6. Integrated plasticity at inhibitory and excitatory synapses in the cerebellar circuit

    PubMed Central

    Mapelli, Lisa; Pagani, Martina; Garrido, Jesus A.; D’Angelo, Egidio

    2015-01-01

    The way long-term potentiation (LTP) and depression (LTD) are integrated within the different synapses of brain neuronal circuits is poorly understood. In order to progress beyond the identification of specific molecular mechanisms, a system in which multiple forms of plasticity can be correlated with large-scale neural processing is required. In this paper we take as an example the cerebellar network, in which extensive investigations have revealed LTP and LTD at several excitatory and inhibitory synapses. Cerebellar LTP and LTD occur in all three main cerebellar subcircuits (granular layer, molecular layer, deep cerebellar nuclei) and correspondingly regulate the function of their three main neurons: granule cells (GrCs), Purkinje cells (PCs) and deep cerebellar nuclear (DCN) cells. All these neurons, in addition to be excited, are reached by feed-forward and feed-back inhibitory connections, in which LTP and LTD may either operate synergistically or homeostatically in order to control information flow through the circuit. Although the investigation of individual synaptic plasticities in vitro is essential to prove their existence and mechanisms, it is insufficient to generate a coherent view of their impact on network functioning in vivo. Recent computational models and cell-specific genetic mutations in mice are shedding light on how plasticity at multiple excitatory and inhibitory synapses might regulate neuronal activities in the cerebellar circuit and contribute to learning and memory and behavioral control. PMID:25999817

  7. Spontaneously resolving cerebellar syndrome as a sequelae of dengue viral infection: a case series from Sri Lanka.

    PubMed

    Weeratunga, Praveen N; Caldera, H P Manjula C; Gooneratne, I Kishara; Gamage, Ranjanie; Perera, W Sujith P; Ranasinghe, Gayan V; Niraj, Mahboob

    2014-06-01

    Sri Lanka is hyperendemic for dengue viral infection. Dengue has a wide spectrum of neurological manifestations including previously reported Sri Lankan cases with a 6th nerve palsy and a cerebellar syndrome from a co-infection with dengue and Epstein-Barr virus. This series describes a spontaneously resolving cerebellar syndrome following a dengue viral infection. Dengue is potentially an important cause of cerebellar syndromes in countries hyperendemic for the disease; patients need further studies to identify the responsible serotypes. PMID:23840070

  8. Shake rattle and roll: the bony labyrinth and aerial descent in squamates.

    PubMed

    Boistel, Renaud; Herrel, Anthony; Lebrun, Renaud; Daghfous, Gheylen; Tafforeau, Paul; Losos, Jonathan B; Vanhooydonck, Bieke

    2011-12-01

    Controlled aerial descent has evolved many times independently in vertebrates. Squamates (lizards and snakes) are unusual in that respect due to the large number of independent origins of the evolution of this behavior. Although some squamates such as flying geckos of the genus Ptychozoon and the flying dragons of the genus Draco show obvious adaptations including skin flaps or enlarged ribs allowing them to increase their surface area and slow down their descent, many others appear unspecialized. Yet, specializations can be expected at the level of the sensory and neural systems allowing animals to maintain stability during controlled aerial descent. The vestibular system is a likely candidate given that it is an acceleration detector and is well-suited to detect changes in pitch, roll and yaw. Here we use conventional and synchrotron ?CT scans to quantify the morphology of the vestibular system in squamates able to perform controlled aerial descent compared to species characterized by a terrestrial or climbing life style. Our results show the presence of a strong phylogenetic signal in the data with the vestibular system in species from the same family being morphologically similar. However, both our shape analysis and an analysis of the dimensions of the vestibular system showed clear differences among animals with different life-styles. Species able to perform a controlled aerial descent differed in the position and shape of the inner ear, especially of the posterior ampulla. Given the limited stability of squamates against roll and the fact that the posterior ampulla is tuned to changes in roll this suggests an adaptive evolution of the vestibular system in squamates using controlled aerial descent. Future studies testing for similar differences in other groups of vertebrates known to use controlled aerial descent are needed to test the generality of this observation. PMID:21700578

  9. 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

  10. Mars Exploration Rover Entry, Descent, and Landing: A Thermal Perspective

    NASA Technical Reports Server (NTRS)

    Tsuyuki, Glenn T.; Sunada, Eric T.; Novak, Keith S.; Kinsella, Gary M.; Phillip, Charles J.

    2005-01-01

    Perhaps the most challenging mission phase for the Mars Exploration Rovers was the Entry, Descent, and Landing (EDL). During this phase, the entry vehicle attached to its cruise stage was transformed into a stowed tetrahedral Lander that was surrounded by inflated airbags through a series of complex events. There was only one opportunity to successfully execute an automated command sequence without any possible ground intervention. The success of EDL was reliant upon the system thermal design: 1) to thermally condition EDL hardware from cruise storage temperatures to operating temperature ranges; 2) to maintain the Rover electronics within operating temperature ranges without the benefit of the cruise single phase cooling loop, which had been evacuated in preparation for EDL; and 3) to maintain the cruise stage propulsion components for the critical turn to entry attitude. Since the EDL architecture was inherited from Mars Pathfinder (MPF), the initial EDL thermal design would be inherited from MPF. However, hardware and implementation differences from MPF ultimately changed the MPF inheritance approach for the EDL thermal design. With the lack of full inheritance, the verification and validation of the EDL thermal design took on increased significance. This paper will summarize the verification and validation approach for the EDL thermal design along with applicable system level thermal testing results as well as appropriate thermal analyses. In addition, the lessons learned during the system-level testing will be discussed. Finally, the in-flight EDL experiences of both MER-A and -B missions (Spirit and Opportunity, respectively) will be presented, demonstrated how lessons learned from Spirit were applied to Opportunity.

  11. Atmospheric Environments for Entry, Descent and Landing (EDL)

    NASA Technical Reports Server (NTRS)

    Justus, Carl G.; Braun, Robert D.

    2007-01-01

    Scientific measurements of atmospheric properties have been made by a wide variety of planetary flyby missions, orbiters, and landers. Although landers can make in-situ observations of near-surface atmospheric conditions (and can collect atmospheric data during their entry phase), the vast majority of data on planetary atmospheres has been collected by remote sensing techniques from flyby and orbiter spacecraft (and to some extent by Earth-based remote sensing). Many of these remote sensing observations (made over a variety of spectral ranges), consist of vertical profiles of atmospheric temperature as a function of atmospheric pressure level. While these measurements are of great interest to atmospheric scientists and modelers of planetary atmospheres, the primary interest for engineers designing entry descent and landing (EDL) systems is information about atmospheric density as a function of geometric altitude. Fortunately, as described in in this paper, it is possible to use a combination of the gas-law relation and the hydrostatic balance relation to convert temperature-versus-pressure, scientific observations into density-versus-altitude data for use in engineering applications. The following section provides a brief introduction to atmospheric thermodynamics, as well as constituents, and winds for EDL. It also gives methodology for using atmospheric information to do "back-of-the-envelope" calculations of various EDL aeroheating parameters, including peak deceleration rate ("g-load"), peak convective heat rate. and total heat load on EDL spacecraft thermal protection systems. Brief information is also provided about atmospheric variations and perturbations for EDL guidance and control issues, and atmospheric issues for EDL parachute systems. Subsequent sections give details of the atmospheric environments for five destinations for possible EDL missions: Venus. Earth. Mars, Saturn, and Titan. Specific atmospheric information is provided for these destinations, and example results are presented for the "back-of-the-envelope" calculations mentioned above.

  12. Stochastic Differential Equation Model for Cerebellar Granule Cell Excitability

    PubMed Central

    Yli-Harja, Olli

    2008-01-01

    Neurons in the brain express intrinsic dynamic behavior which is known to be stochastic in nature. A crucial question in building models of neuronal excitability is how to be able to mimic the dynamic behavior of the biological counterpart accurately and how to perform simulations in the fastest possible way. The well-established Hodgkin-Huxley formalism has formed to a large extent the basis for building biophysically and anatomically detailed models of neurons. However, the deterministic Hodgkin-Huxley formalism does not take into account the stochastic behavior of voltage-dependent ion channels. Ion channel stochasticity is shown to be important in adjusting the transmembrane voltage dynamics at or close to the threshold of action potential firing, at the very least in small neurons. In order to achieve a better understanding of the dynamic behavior of a neuron, a new modeling and simulation approach based on stochastic differential equations and Brownian motion is developed. The basis of the work is a deterministic one-compartmental multi-conductance model of the cerebellar granule cell. This model includes six different types of voltage-dependent conductances described by Hodgkin-Huxley formalism and simple calcium dynamics. A new model for the granule cell is developed by incorporating stochasticity inherently present in the ion channel function into the gating variables of conductances. With the new stochastic model, the irregular electrophysiological activity of an in vitro granule cell is reproduced accurately, with the same parameter values for which the membrane potential of the original deterministic model exhibits regular behavior. The irregular electrophysiological activity includes experimentally observed random subthreshold oscillations, occasional spontaneous spikes, and clusters of action potentials. As a conclusion, the new stochastic differential equation model of the cerebellar granule cell excitability is found to expand the range of dynamics in comparison to the original deterministic model. Inclusion of stochastic elements in the operation of voltage-dependent conductances should thus be emphasized more in modeling the dynamic behavior of small neurons. Furthermore, the presented approach is valuable in providing faster computation times compared to the Markov chain type of modeling approaches and more sophisticated theoretical analysis tools compared to previously presented stochastic modeling approaches. PMID:18463700

  13. Bilateral disruption of conditioned responses after unilateral blockade of cerebellar output in the decerebrate ferret.

    PubMed Central

    Ivarsson, M; Svensson, P; Hesslow, G

    1997-01-01

    1. Lesions of the cerebellar cortex can abolish classically conditioned eyeblink responses, but some recovery with retraining has been observed. It has been suggested that the recovered responses are generated by the intact contralateral cerebellar hemisphere. In order to investigate this suggestion, bilaterally acquired conditioned responses were studied after the unilateral blockade of cerebellar output. 2. Decerebrate ferrets were trained with ipsilateral electrical forelimb stimulation (300 ms, 50 Hz, 1 mA) as the conditioned stimulus and bilaterally applied peri-orbital stimulation (40 ms, 50 Hz, 3 mA) as the unconditioned stimulus. The conditioned and unconditioned eyeblink responses were monitored by EMG recordings from the orbicularis oculi muscle. The output from one cerebellar hemisphere was blocked either by injecting small amounts of lignocaine (lidocaine; 0.5-1.0 microliter) into the brachium conjunctivum, or by a restricted mechanical lesion of the brainstem rostral to the cerebellum. 3. As described by previous investigators, the unilateral blockade of cerebellar output abolished ipsilateral conditioned responses. 4. More importantly, such blockade also abolished or strongly depressed contralateral conditioned responses. When mechanical lesions of the brachium conjunctivum were made, contralateral responses, in contrast to ipsilateral responses, recovered within 1-2.5 h. 5. When the unconditioned stimulus was removed on one side, causing extinction of conditioned responses on this side, conditioned responses were temporarily depressed on the trained side as well. 6. Unilateral interruption of cerebellar output had no clear effect on contralateral unconditioned reflex responses. 7. The results demonstrate that one cerebellar hemisphere in ferrets exerts a marked control of contralateral conditioned eyeblink responses, probably via premotor neurones involved specifically in conditioned, and not in unconditioned, responses. PMID:9234206

  14. 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

  15. Motor dysfunction in cerebellar Purkinje cell-specific vesicular GABA transporter knockout mice

    PubMed Central

    Kayakabe, Mikiko; Kakizaki, Toshikazu; Kaneko, Ryosuke; Sasaki, Atsushi; Nakazato, Yoichi; Shibasaki, Koji; Ishizaki, Yasuki; Saito, Hiromitsu; Suzuki, Noboru; Furuya, Nobuhiko; Yanagawa, Yuchio

    2014-01-01

    ?-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the adult mammalian central nervous system and plays modulatory roles in neural development. The vesicular GABA transporter (VGAT) is an essential molecule for GABAergic neurotransmission due to its role in vesicular GABA release. Cerebellar Purkinje cells (PCs) are GABAergic projection neurons that are indispensable for cerebellar function. To elucidate the significance of VGAT in cerebellar PCs, we generated and characterized PC-specific VGAT knockout (L7-VGAT) mice. VGAT mRNAs and proteins were specifically absent in the 40-week-old L7-VGAT PCs. The morphological characteristics, such as lamination and foliation of the cerebellar cortex, of the L7-VGAT mice were similar to those of the control littermate mice. Moreover, the protein expression levels and patterns of pre- (calbindin and parvalbumin) and postsynaptic (GABA-A receptor ?1 subunit and gephyrin) molecules between the L7-VGAT and control mice were similar in the deep cerebellar nuclei that receive PC projections. However, the L7-VGAT mice performed poorly in the accelerating rotarod test and displayed ataxic gait in the footprint test. The L7-VGAT mice also exhibited severer ataxia as VGAT deficits progressed. These results suggest that VGAT in cerebellar PCs is not essential for the rough maintenance of cerebellar structure, but does play an important role in motor coordination. The L7-VGAT mice are a novel model of ataxia without PC degeneration, and would also be useful for studying the role of PCs in cognition and emotion. PMID:24474904

  16. The Genesis of Cerebellar GABAergic Neurons: Fate Potential and Specification Mechanisms

    PubMed Central

    Leto, Ketty; Rolando, Chiara; Rossi, Ferdinando

    2012-01-01

    All cerebellar neurons derive from progenitors that proliferate in two germinal neuroepithelia: the ventricular zone (VZ) generates GABAergic neurons, whereas the rhombic lip is the origin of glutamatergic types. Among VZ-derivatives, GABAergic projection neurons, and interneurons are generated according to distinct strategies. Projection neurons (Purkinje cells and nucleo-olivary neurons) are produced at the onset of cerebellar neurogenesis by discrete progenitor pools located in distinct VZ microdomains. These cells are specified within the VZ and acquire mature phenotypes according to cell-autonomous developmental programs. On the other hand, the different categories of inhibitory interneurons derive from a single population of Pax-2-positive precursors that delaminate into the prospective white matter (PWM), where they continue to divide up to postnatal development. Heterotopic/heterochronic transplantation experiments indicate that interneuron progenitors maintain full developmental potentialities up to the end of cerebellar development and acquire mature phenotypes under the influence of environmental cues present in the PWM. Furthermore, the final fate choice occurs in postmitotic cells, rather than dividing progenitors. Extracerebellar cells grafted to the prospective cerebellar white matter are not responsive to local neurogenic cues and fail to adopt clear cerebellar identities. Conversely, cerebellar cells grafted to extracerebellar regions retain typical phenotypes of cerebellar GABAergic interneurons, but acquire type-specific traits under the influence of local cues. These findings indicate that interneuron progenitors are multipotent and sensitive to spatio-temporally patterned environmental signals that regulate the genesis of different categories of interneurons, in precise quantities and at defined times and places. PMID:22363268

  17. Tracer-Based Determination of Vortex Descent in the 1999-2000 Arctic Winter

    NASA Technical Reports Server (NTRS)

    Greenblatt, Jeffery B.; Jost, Hans-Juerg; Loewenstein, Max; Podolske, James R.; Hurst, Dale F.; Elkins, James W.; Schauffler, Sue M.; Atlas, Elliot L.; Herman, Robert L.; Webster, Christopher R.

    2001-01-01

    A detailed analysis of available in situ and remotely sensed N2O and CH4 data measured in the 1999-2000 winter Arctic vortex has been performed in order to quantify the temporal evolution of vortex descent. Differences in potential temperature (theta) among balloon and aircraft vertical profiles (an average of 19-23 K on a given N2O or CH4 isopleth) indicated significant vortex inhomogeneity in late fall as compared with late winter profiles. A composite fall vortex profile was constructed for November 26, 1999, whose error bars encompassed the observed variability. High-latitude, extravortex profiles measured in different years and seasons revealed substantial variability in N2O and CH4 on theta surfaces, but all were clearly distinguishable from the first vortex profiles measured in late fall 1999. From these extravortex-vortex differences, we inferred descent prior to November 26: 397+/-15 K (1sigma) at 30 ppbv N2O and 640 ppbv CH4, and 28+/-13 K above 200 ppbv N2O and 1280 ppbv CH4. Changes in theta were determined on five N2O and CH4 isopleths from November 26 through March 12, and descent rates were calculated on each N2O isopleth for several time intervals. The maximum descent rates were seen between November 26 and January 27: 0.82+/-0.20 K/day averaged over 50-250 ppbv N2O. By late winter (February 26-March 12), the average rate had decreased to 0.10+/-0.25 K/day. Descent rates also decreased with increasing N2O; the winter average (November 26-March 5) descent rate varied from 0.75+/-0.10 K/day at 50 ppbv to 0.40+/-0.11 K/day at 250 ppbv. Comparison of these results with observations and models of descent in prior years showed very good overall agreement. Two models of the 1999-2000 vortex descent, SLIMCAT and REPROBUS, despite theta offsets with respect to observed profiles of up to 20 K on most tracer isopleths, produced descent rates that agreed very favorably with the inferred rates from observation.

  18. Global patterns of prostate cancer incidence, aggressiveness, and mortality in men of african descent.

    PubMed

    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

  19. 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

  20. Tissue printed cells from teleost electrosensory and cerebellar structures.

    PubMed

    Kotecha, S A; Eley, D W; Turner, R W

    1997-09-22

    A modification of the tissue printing technique was used to acutely isolate and culture cells from the electrosensory lateral line lobe (ELL), corpus cerebelli (CCb), and eminentia granularis pars posterior (EGp) of the adult weakly electric fish, Apteronotus leptorhynchus. Cells were isolated without the use of proteolytic enzymes and tissue printed as a monolayer onto glass coverslips through centrifugation in the presence of a medium designed to preserve cell structure. Tissue printed cells were reliably distributed in an organotypic fashion that allowed for the identification of anatomical boundaries between the ELL and cerebellar regions, distinct sensory maps in the ELL, and specific cell laminae. Many cells were isolated with an excellent preservation of soma-dendritic structure, permitting direct identification of all electrosensory cell classes according to morphological or immunocytochemical criteria. Several classes of glial cells were isolated, including small diameter microglia and the complex arborizations of oligodendrocytes. A plexus of fine processes were often isolated in conjunction with cell somata and dendrites, potentially preserving synaptic contacts in vitro. In particular, immunolabel for gamma-aminobutyric acid (GABA) revealed a previously unrecognized network of GABAergic axonal processes in the CCb and EGp granule cell body and molecular layers. Tissue printed cells were readily maintained with an organotypic distribution of glial and neuronal elements for up to 27 days in culture. This procedure will allow for the isolation of electrosensory cells from adult central nervous system for electrophysiological analyses of membrane properties or synaptic interactions between identified cells. PMID:9295152

  1. Endovascular treatment for ruptured distal anterior inferior cerebellar artery aneurysm.

    PubMed

    Oh, Jae-Sang; Yoon, Seok-Mann; Shim, Jai-Joon; Bae, Hack-Gun; Yoon, Il-Gyu

    2014-03-01

    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

  2. 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

  3. Laterality Differences in Cerebellar-Motor Cortex Connectivity.

    PubMed

    Schlerf, John E; Galea, Joseph M; Spampinato, Danny; Celnik, Pablo A

    2015-07-01

    Lateralization of function is an important organizational feature of the motor system. Each effector is predominantly controlled by the contralateral cerebral cortex and the ipsilateral cerebellum. Transcranial magnetic stimulation studies have revealed hemispheric differences in the stimulation strength required to evoke a muscle response from the primary motor cortex (M1), with the dominant hemisphere typically requiring less stimulation than the nondominant. The current study assessed whether the strength of the connection between the cerebellum and M1 (CB-M1), known to change in association with motor learning, have hemispheric differences and whether these differences have any behavioral correlate. We observed, in right-handed individuals, that the connection between the right cerebellum and left M1 is typically stronger than the contralateral network. Behaviorally, we detected no lateralized learning processes, though we did find a significant effect on the amplitude of reaching movements across hands. Furthermore, we observed that the strength of the CB-M1 connection is correlated with the amplitude variability of reaching movements, a measure of movement precision, where stronger connectivity was associated with better precision. These findings indicate that lateralization in the motor system is present beyond the primary motor cortex, and points to an association between cerebellar M1 connectivity and movement execution. PMID:24436320

  4. Glial activation modulates glutamate neurotoxicity in cerebellar granule cell cultures.

    PubMed

    Pérez-Capote, Kamil; Serratosa, Joan; Solà, Carme

    2004-02-01

    We studied the influence of glial cells on the neuronal response to glutamate toxicity in cerebellar granule cell cultures. We compared the effect of glutamate on neuronal viability in neuronal vs. neuronal-glial cultures and determined this effect after pretreating the cultures with the lipopolysaccharide (LPS) of Escherichia coli, agent widely used to induce glial activation. Morphological changes in glial cells and nitric oxide (NO) production were evaluated as indicators of glial activation. We observed that glutamate neurotoxicity in neuronal-glial cultures was attenuated in a certain range of glutamate concentration when compared to neuronal cultures, but it was enhanced at higher glutamate concentrations. This enhanced neurotoxicity was associated with morphological changes in astrocytes and microglial cells in the absence of NO production. LPS treatment induced morphological changes in glial cells in neuronal-glial cultures as well as NO production. These effects occurred in the absence of significant neuronal death. However, when LPS-pretreated cultures were treated with glutamate, the sensitivity of neuronal-glial cultures to glutamate neurotoxicity was increased. This was accompanied by additional morphological changes in glial cells in the absence of a further increase in NO production. These results suggest that quiescent glial cells protect neuronal cells from glutamate neurotoxicity, but reactive glial cells increase glutamate neurotoxicity. Therefore, glial cells play a key role in the neuronal response to a negative stimulus, suggesting that this response can be modified through an action on glial cells. PMID:14730699

  5. Cerebro-cerebellar connectivity is increased in primary lateral sclerosis.

    PubMed

    Meoded, Avner; Morrissette, Arthur E; Katipally, Rohan; Schanz, Olivia; Gotts, Stephen J; Floeter, Mary Kay

    2015-01-01

    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

  6. Aerodynamics of Reentry Vehicle Clipper at Descent Phase

    NASA Astrophysics Data System (ADS)

    Semenov, Yu. P.; Reshetin, A. G.; Dyadkin, A. A.; Petrov, N. K.; Simakova, T. V.; Tokarev, V. A.

    2005-02-01

    From Gagarin spacecraft to reusable orbiter Buran, RSC Energia has traveled a long way in the search for the most optimal and, which is no less important, the most reliable spacecraft for manned space flight. During the forty years of space exploration, in cooperation with a broad base of subcontractors, a number of problems have been solved which assure a safe long stay in space. Vostok and Voskhod spacecraft were replaced with Soyuz supporting a crew of three. During missions to a space station, it provides crew rescue capability in case of a space station emergency at all times (the spacecraft life is 200 days).The latest modification of Soyuz spacecraft -Soyuz TMA -in contrast to its predecessors, allows to become a space flight participant to a person of virtually any anthropometric parameters with a mass of 50 to 95 kg capable of withstanding up to 6 g load during descent. At present, Soyuz TMA spacecraft are the state-of-the-art, reliable and only means of the ISS crew delivery, in-flight support and return. Introduced on the basis of many years of experience in operation of manned spacecraft were not only the principles of deep redundancy of on-board systems and equipment, but, to assure the main task of the spacecraft -the crew return to Earth -the principles of functional redundancy. That is, vital operations can be performed by different systems based on different physical principles. The emergency escape system that was developed is the only one in the world that provides crew rescue in case of LV failure at any phase in its flight. Several generations of space stations that have been developed have broadened, virtually beyond all limits, capabilities of man in space. The docking system developed at RSC Energia allowed not only to dock spacecraft in space, but also to construct in orbit various complex space systems. These include large space stations, and may include in the future the in-orbit construction of systems for the exploration of the Moon and Mars.. Logistics spacecraft Progress have been flying regularly since 1978. The tasks of these unmanned spacecraft include supplying the space station with all the necessities for long-duration missions, such as propellant for the space station propulsion system, crew life support consumables, scientific equipment for conducting experiments. Various modifications of the spacecraft have expanded the space station capabilities. 1988 saw the first, and, much to our regret, the last flight of the reusable orbiter Buran.. Buran could deliver to orbit up to 30 tons of cargo, return 20 tons to Earth and have a crew of up to 10. However, due to our country's economic situation the project was suspended.

  7. 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

  8. 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

  9. [Cerebellar abscess due to infection with the anaerobic bacteria fusobacterium nucleatum: a case report].

    PubMed

    Shimogawa, Takafumi; Sayama, Tetsuro; Haga, Sei; Akiyama, Tomoaki; Morioka, Takato

    2015-02-01

    We report a rare case of cerebellar abscess produced by anaerobic bacteria. A 76-year-old man was admitted to our hospital with a history of fever, vomiting, and dizziness lasting 14 days. Computed tomography(CT)scan and magnetic resonance images showed the presence of a multiloculated cerebellar abscess with a right subdural abscess. The patient underwent aspiration of the abscess through a suboccipital craniotomy. Fusobacterium nucleatum, which is an anaerobic bacteria naturally present in the human oral cavity, was detected in cultures of the aspirated abscess. The patient was administered antibiotic treatment combined with hyperbaric oxygen therapy(HBO). The symptoms were briefly relieved but the cerebellar abscess recurred, which required a second aspiration. The combined treatment with antibiotics and HBO was maintained after the second operation. After 6 weeks of treatment, the cerebellar abscess was completely controlled. We conclude that antibiotic treatment combined with HBO is useful for treatment of cerebellar abscesses caused by infection with anaerobic bacteria. PMID:25672555

  10. Cerebellar hemorrhage on MRI in preterm newborns associated with abnormal neurological outcome

    PubMed Central

    Tam, Emily W.Y.; Rosenbluth, Glenn; Rogers, Elizabeth E.; Ferriero, Donna M.; Glidden, David; Goldstein, Ruth B.; Glass, Hannah C.; Piecuch, Robert E.; Barkovich, A. James

    2010-01-01

    Objective To investigate the relationship between cerebellar hemorrhage in preterm infants seen on MRI but not ultrasound and neurodevelopmental outcome. Study design MR images from a cohort study of MRI in preterm newborns were reviewed for cerebellar hemorrhage. Children were assessed at mean 4.8 years with neurological examination and developmental testing using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III). Results Of 131 preterm newborns, cerebellar hemorrhage was seen on both ultrasound and MRI in 3 newborns; smaller hemorrhages seen only on MRI in 10 (total of incidence of 10%). Adjusting for gestational age at birth, intraventricular hemorrhage, and white matter injury, cerebellar hemorrhage detectable only by MRI was associated with 5.0-fold increased odds of abnormal neurological examination compared with those without hemorrhage (outcome data in 74%). No association was found with scores on WPPSI-III testing. Conclusions Cerebellar hemorrhage is not uncommon in preterm newborns. Although associated with neurologic abnormalities, hemorrhage seen only on MRI is associated with much more optimistic outcomes than that visible by ultrasound. PMID:20833401

  11. Huygens’ entry and descent through Titan's atmosphere—Methodology and results of the trajectory reconstruction

    NASA Astrophysics Data System (ADS)

    Kazeminejad, Bobby; Atkinson, David H.; Pérez-Ayúcar, Miguel; Lebreton, Jean-Pierre; Sollazzo, Claudio

    2007-11-01

    The European Space Agency's Huygens probe separated from the NASA Cassini spacecraft on 25 December 2004, after having been attached for a 7-year interplanetary journey and three orbits around Saturn. The probe reached the predefined NASA/ESA interface point on 14 January 2005 at 09:05:52.523 (UTC) and performed a successful entry and descent sequence. The probe softly impacted on Titan's surface on the same day at 11:38:10.77 (UTC) with a speed of about 4.54 m/s. The probe entry and descent trajectory was reconstructed from the estimated initial state vector provided by the Cassini Navigation team, the probe housekeeping data, and measurements from the scientific payload. This paper presents the methodology and discuss the results of the reconstruction effort. Furthermore the probe roll rate was reconstructed prior to the main entry phase deceleration pulse and throughout the entire descent phase under the main and drogue parachute.

  12. 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

  13. 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.

  14. 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

  15. Eye Movement Patterns of the Elderly during Stair Descent:Effect of Illumination

    NASA Astrophysics Data System (ADS)

    Kasahara, Satoko; Okabe, Sonoko; Nakazato, Naoko; Ohno, Yuko

    The relationship between the eye movement pattern during stair descent and illumination was studied in 4 elderly people in comparison with that in 5 young people. The illumination condition was light (85.0±30.9 lx) or dark (0.7±0.3 lx), and data of eye movements were obtained using an eye mark recorder. A flight of 15 steps was used for the experiment, and data on 3 steps in the middle, on which the descent movements were stabilized, were analyzed. The elderly subjects pointed their eyes mostly directly in front in the facial direction regardless of the illumination condition, but the young subjects tended to look down under the light condition. The young subjects are considered to have confirmed the safety of the front by peripheral vision, checked the stepping surface by central vision, and still maintained the upright position without leaning forward during stair descent. The elderly subjects, in contrast, always looked at the visual target by central vision even under the light condition and leaned forward. The range of eye movements was larger vertically than horizontally in both groups, and a characteristic eye movement pattern of repeating a vertical shuttle movement synchronous with descent of each step was observed. Under the dark condition, the young subjects widened the range of vertical eye movements and reduced duration of fixation. The elderly subjects showed no change in the range of eye movements but increased duration of fixation during stair descent. These differences in the eye movements are considered to be compensatory reactions to narrowing of the vertical visual field, reduced dark adaptation, and reduced dynamic visual acuity due to aging. These characteristics of eye movements of the elderly lead to an anteriorly leaned posture and lack of attention to the front during stair descent.

  16. 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.

  17. 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

  18. Agenesis of the vermis with fusion of the cerebellar hemispheres, septo-optic dysplasia and associated anomalies

    Microsoft Academic Search

    J. Michaud; E. M. Mizrahi; H. Urich

    1982-01-01

    Agenesis of the cerebellar vermis with fusion of the dentate nuclei and cerebellar hemispheres (rhombencephalosynapsis) is a rare cerebral malformation. We report the case of a 7-h-old girl whose mother had taken the drug phencyclidine during the first 6 weeks of pregnancy. Absence of the septum pellucidum, hypoplasia of the commissural system, optic nerves, chiasm and tracts, moderate hydrocephalus, and

  19. Topographical organization of pathways from somatosensory cortex through the pontine nuclei to tactile regions of the rat cerebellar hemispheres

    Microsoft Academic Search

    Trygve B. Leergaard; Sveinung Lillehaug; Erik De Schutter; James M. Bower; Jan G. Bjaalie

    2006-01-01

    The granule cell layer of the cerebellar hemispheres contains a patchy and noncontinuous map of the body surface, consisting of a complex mosaic of multiple perioral tactile representations. Previous physiological studies have shown that cerebrocerebellar mossy fibre projections, conveyed through the pontine nuclei, are mapped in registration with peripheral tactile projections to the cerebellum. In contrast to the fractured cerebellar

  20. Cerebellar Norepinephrine Modulates Learning of Delay Classical Eyeblink Conditioning: Evidence for Post-Synaptic Signaling via PKA

    ERIC Educational Resources Information Center

    Fister, Mathew; Bickford, Paula C.; Cartford, M. Claire; Samec, Amy

    2004-01-01

    The neurotransmitter norepinephrine (NE) has been shown to modulate cerebellar-dependent learning and memory. Lesions of the nucleus locus coeruleus or systemic blockade of noradrenergic receptors has been shown to delay the acquisition of several cerebellar-dependent learning tasks. To date, no studies have shown a direct involvement of…

  1. 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.

  2. Minimum-Cost Aircraft Descent Trajectories with a Constrained Altitude Profile

    NASA Technical Reports Server (NTRS)

    Wu, Minghong G.; Sadovsky, Alexander V.

    2015-01-01

    An analytical formula for solving the speed profile that accrues minimum cost during an aircraft descent with a constrained altitude profile is derived. The optimal speed profile first reaches a certain speed, called the minimum-cost speed, as quickly as possible using an appropriate extreme value of thrust. The speed profile then stays on the minimum-cost speed as long as possible, before switching to an extreme value of thrust for the rest of the descent. The formula is applied to an actual arrival route and its sensitivity to winds and airlines' business objectives is analyzed.

  3. 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.

  4. Relationship between fuel consumption and altitude for commercial aircraft during descent: Preliminary assessment with a genetic algorithm

    Microsoft Academic Search

    Enis T. Turgut; Marc A. Rosen

    Despite fuel flow rates being low during descent compared to climb and cruise, the potential exists for significant fuel savings during that phase of flight. Increased fuel use, costs and related environmental impacts are associated with stepped descents leading to low level flights and holding in the air due to delays or slot conflicts. Except for the Base of Aircraft

  5. Nothing can be coincidence: synaptic inhibition and plasticity in the cerebellar nuclei

    PubMed Central

    Pugh, Jason R.; Raman, Indira M.

    2009-01-01

    Many cerebellar neurons fire spontaneously, generating 10–100 action potentials per second even without synaptic input. This high basal activity correlates with information-coding mechanisms that differ from those of cells that are quiescent until excited synaptically. For example, in the deep cerebellar nuclei, Hebbian patterns of coincident synaptic excitation and postsynaptic firing fail to induce long-term increases in the strength of excitatory inputs. Instead, excitatory synaptic currents are potentiated by combinations of inhibition and excitation that resemble the activity of Purkinje and mossy fiber afferents that is predicted to occur during cerebellar associative learning tasks. Such results indicate that circuits with intrinsically active neurons have rules for information transfer and storage that distinguish them from other brain regions. PMID:19178955

  6. JC virus granule cell neuronopathy: A cause of infectious cerebellar degeneration.

    PubMed

    Henry, Carole; Jouan, Fanny; De Broucker, Thomas

    2015-07-15

    JC virus (JCV) infection of glial cells can lead to progressive multifocal leukoencephalopathy (PML) in immunocompromised patients. A newly described phenotype of the infection is infection of neurons. This distinct clinical and radiological syndrome is named JCV granule cell neuronopathy, characterized by exclusive or predominant cerebellar atrophy. We report the clinical and radiological longitudinal findings of 5 HIV-infected patients referred to us between September 2004 and November 2011 who exhibited JCV granule cell neuronopathy (4 probable cases and 1 possible). The association of immunocompromised status, progressive cerebellar syndrome, MRI abnormalities with cortical cerebellar atrophy and cerebrospinal fluid positive for JCV on PCR allowed for a highly probable diagnosis. The reversal of the immunocompromised status is the only way to stop the disease evolution. Motor functioning can remain impaired, but the illness itself, unlike progressive multifocal leukoencephalopathy, does not seem to threaten life. PMID:26003226

  7. Late-onset obsessive-compulsive disorder associated with left cerebellar lesion.

    PubMed

    Tonna, Matteo; Ottoni, Rebecca; Ossola, Paolo; De Panfilis, Chiara; Marchesi, Carlo

    2014-08-01

    The onset of obsessive-compulsive disorder (OCD) after age 50 is rare and generally related to an organic etiology. An involvement of fronto-striatal circuits has been strongly suggested, whereas cerebellum remains so far scarcely explored. We present here the description of a "pure" late-onset OCD associated with a cerebellar lesion, neither comorbid with other mental disorders nor with neurological syndromes. To our knowledge, this condition was not previously described in literature. The patient is a 62-year-old woman who developed a late-onset OCD associated with a left cerebellar lesion due to an arachnoid cyst in the left posterior fossa. We debate the possible role of the cerebellar lesion in favoring a transition from a predisposing liability (namely an obsessive-compulsive personality disorder and a depressive status) to the onset of OCD in this woman. PMID:24771488

  8. Acute behavioural change in a young woman evolving towards cerebellar syndrome.

    PubMed

    Naeije, G; de Hemptinne, Q; Depondt, C; Pandolfo, M; Legros, B

    2010-07-01

    Symptomatic paraneoplastic neurological syndromes are rare manifestations of cancers. Recently, a new type of encephalitis associated with antibodies against NMDA-glutamate receptors (A-NMDAR) was defined. The patients, usually young women, present with acute onset of psychiatric symptoms and decreased consciousness. We describe the case of a patient who presented with acute onset of delirium alternating with sub-comatose state. Blood analyses were within normal range. Lumbar puncture showed lymphocytic pleiocytosis. Brain gadolinium injected MRI, brain and full body PET scans were normal. Investigations led to suspect a paraneoplastic syndrome and a right ovarian teratoma and A-NMDAR were found and the teratoma removed. The remaining sequellae included a cerebellar syndrome seldom described before. As cerebellar and cortical neurons share the same excitatory pathway through NMDA-glutamate receptors, the cerebellar function impairment observed in our patient could be explained by a disabling action on glutamate NMDAR by the A-NMDAR. PMID:20347215

  9. Contactin-associated protein-2 antibodies in non-paraneoplastic cerebellar ataxia

    PubMed Central

    Becker, Esther B E; Zuliani, Luigi; Pettingill, Rosemary; Lang, Bethan; Waters, Patrick; Dulneva, Anna; Sobott, Frank; Wardle, Mark; Graus, Francesc; Bataller, Luis; Robertson, Neil P

    2012-01-01

    Background Relatively few studies have searched for potentially pathogenic antibodies in non-paraneoplastic patients with cerebellar ataxia. Methods and Results We first screened sera from 52 idiopathic ataxia patients for binding of serum IgG antibodies to cerebellar neurons. One strong-binding serum was selected for immunoprecipitation and mass spectrometry, which resulted in the identification of contactin-associated protein 2 (CASPR2) as a major antigen. CASPR2 antibodies were then found by a cell-based assay in 9/88 (10%) ataxia patients, compared to 3/144 (2%) multiple sclerosis or dementia controls (p=0.011). CASPR2 is strongly expressed in the cerebellum, only partly in association with voltage-gated potassium channels. Conclusions Prospective studies are now needed to see whether identification of CASPR2 antibodies has relevance for the diagnosis and treatment of idiopathic cerebellar ataxia. PMID:22338029

  10. Cerebellar inhibitory input to the inferior olive decreases electrical coupling and blocks subthreshold oscillations.

    PubMed

    Lefler, Yaara; Yarom, Yosef; Uusisaari, Marylka Yoe

    2014-03-19

    GABAergic projection neurons in the cerebellar nuclei (CN) innervate the inferior olive (IO) that in turn is the source of climbing fibers targeting Purkinje neurons in the cerebellar cortex. Anatomical evidence suggests that CN synapses modulate electrical coupling between IO neurons. In vivo studies indicate that they are also involved in controlling synchrony and rhythmicity of IO neurons. Here, we demonstrate using virally targeted channelrhodopsin in the cerebellar nucleo-olivary neurons that synaptic input can indeed modulate both the strength and symmetry of electrical coupling between IO neurons and alter network activity. Similar synaptic modifications of electrical coupling are likely to occur in other brain regions, where rapid modification of the spatiotemporal features of the coupled networks is needed to adequately respond to behavioral demands. PMID:24656256

  11. Cerebellar atrophy and monoclonal gammopathy of undetermined significance: a possible correlation?

    PubMed

    Galiè, E; Maschio, M; Jandolo, B

    2005-09-01

    Central Nervous System involvement in Monoclonal gammopathies of undetermined significance has seldomly been reported and in all the cases a demyelinating disease was found. We report the case of a young man who had been suffering for five years of progressive cerebellar syndrome. MRI showed marked cerebellar vermis atrophy. An IgG lambda monoclonal gammopathy was revealed in the serum. Cerebrospinal fluid examination showed oligoclonal bands and elevated Link-Index. Serologic research for HBV, HCV, HIV, Lues, Rubella, Measles was negative, as also genetic analysis for SCA1, SCA2, SCA3, SCA7 and Friederich's ataxia. Nerve conduction studies were normal. Plasmatic vit.E was low, but treatment with high doses of tocopherol was ineffective. i.v. immunoglobulins and steroids obtained only transient clinical benefits. In conclusion, we hypothesize a pathogenetic role of the IgG in this cerebellar atrophy. PMID:16270536

  12. Acquired pendular nystagmus with oscillopsia in multiple sclerosis: a sign of cerebellar nuclei disease

    PubMed Central

    Aschoff, Jürgen C.; Conrad, B.; Kornhuber, H. H.

    1974-01-01

    In an unselected series of 644 cases of multiple sclerosis, 25 cases with acquired pendular nystagmus were found. Ten additional cases of pendular nystagmus in multiple sclerosis were investigated, and four cases from the literature are analysed. Acquired pendular nystagmus is purely sinusoidal in form, ceases with eye closure, is accompanied by oscillopsia, often monocular and vertical in direction, and never accompanied by optokinetic inversion. This is different from congenital nystagmus. Acquired pendular nystagmus in multiple sclerosis shows a high correlation with holding tremor of head and arm and with trunk ataxia, and must therefore be viewed as a result of lesions of cerebellar nuclei or their fibre connections with the brain-stem. Supporting evidence is discussed. The results fit into a theory of cerebellar function according to which the cerebellar nuclei are involved in the maintenance of positions. PMID:4836752

  13. Epistatic interactions between Chd7 and Fgf8 during cerebellar development

    PubMed Central

    Basson, M Albert

    2014-01-01

    CHARGE syndrome is a rare, autosomal dominant condition caused by mutations in the CHD7 gene. Although central nervous system defects have been reported, the detailed description and analysis of these anomalies in CHARGE syndrome patients lag far behind the description of other, more easily observed defects. We recently described cerebellar abnormalities in CHARGE syndrome patients and used mouse models to identify the underlying causes. Our studies identified altered expression of the homeobox genes Otx2 and Gbx2 in the developing neural tube of Chd7?/? embryos. Furthermore, we showed that the expression of Fgf8 is sensitive to Chd7 gene dosage and demonstrated an epistatic relationship between these genes during cerebellar vermis development. These findings provided, for the first time, an example of cerebellar vermis hypoplasia in a human syndrome that can be linked to deregulated FGF signaling. I discuss some of these observations and their implications for CHARGE syndrome. PMID:25054096

  14. Biosonar signals and cerebellar auditory neurons of the mustached bat.

    PubMed

    Horikawa, J; Suga, N

    1986-06-01

    In the vermis (VIp, VIIa, VIIp, and VIII), crus, and paraflocculus of unanesthetized mustached bats Pteronotus parnellii parnellii, responses of single neurons to acoustic stimuli were studied. The stimuli delivered were constant-frequency (CF) tones, frequency-modulated (FM) sounds, noise bursts (NBs), and sounds similar to the orientation sounds (pulses) of the species and echoes. The effect of ablation of the cerebellar cortex on vocalization was also investigated to explore whether the cerebellum was involved in sound emission. In the cerebellum of the mustached bat, auditory neurons are predominantly tuned to frequencies within the bands between 23 and 30, 55 and 63, or 85 and 94 kHz, which are found in the first, second, and third harmonics of bat's biosonar signals, respectively. The first harmonic is represented in the paraflocculus. The second harmonic is represented in vermis VIp and VIIa and crus I and IIa. The third harmonic is mainly represented in vermis VIIp and crus IIp. Different lobules represent different frequencies, but there is no systematic tonotopic representation in each lobule. The resting frequency of the CF component of the second harmonic (CF2) of the pulse differs among bats. The majority of auditory neurons in vermis VIp and VIIa and crus IIa are tuned to the CF2 frequency of the bat's own pulse. The frequency-tuning curves of cerebellar neurons are broader than those of peripheral neurons, reflected in significantly lower quality factors of Q-10, -30, and -50 dBs. In vermis VIp and VIIa, there are tiny clusters of FM-FM and CF/CF combination-sensitive neurons. They show strong facilitation of responses when two FM or CF sounds are delivered with particular relationships in the frequency, amplitude, and time domains. Because the clusters of these combination-sensitive neurons in the cerebellum are so small, we found no sign of a systematic representation of certain acoustic parameters, unlike that found in the auditory cortex. In vermis VIp and VIIa, there is a large cluster of NB-sensitive neurons that are more sensitive to NBs than to CF tones. The wider the bandwidth of the NBs, the better are the responses of these NB-sensitive neurons. The ablation of the vermis (VIp, VIIa, and VIIp), crus, and paraflocculus increases the variation of the CF frequency of the pulse. The ablation of the crus and paraflocculus causes a clear increase in the variation of CF frequency. The ablation of vermis (VIp, VIIa, and VIIp) has only a small effect on the variation. Any of the above ablations has little effect on the repetition rate of the pulse emission and the duration of pulses.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3734857

  15. Direction discrimination thresholds of vestibular and cerebellar nuclei neurons.

    PubMed

    Liu, Sheng; Yakusheva, Tatyana; Deangelis, Gregory C; Angelaki, Dora E

    2010-01-13

    To understand the roles of the vestibular system in perceptual detection and discrimination of self-motion, it is critical to account for response variability in computing the sensitivity of vestibular neurons. Here we study responses of neurons with no eye movement sensitivity in the vestibular (VN) and rostral fastigial nuclei (FN) using high-frequency (2 Hz) oscillatory translational motion stimuli. The axis of translation (i.e., heading) varied slowly (1 degrees /s) in the horizontal plane as the animal was translated back and forth. Signal detection theory was used to compute the threshold sensitivity of VN/FN neurons for discriminating small variations in heading around all possible directions of translation. Across the population, minimum heading discrimination thresholds averaged 16.6 degrees +/- 1 degrees SE for FN neurons and 15.3 degrees +/- 2.2 degrees SE for VN neurons, severalfold larger than perceptual thresholds for heading discrimination. In line with previous studies and theoretical predictions, maximum discriminability was observed for directions where firing rate changed steeply as a function of heading, which occurs at headings approximately perpendicular to the maximum response direction. Forward/backward heading thresholds tended to be lower than lateral motion thresholds, and the ratio of lateral over forward heading thresholds averaged 2.2 +/- 6.1 (geometric mean +/- SD) for FN neurons and 1.1 +/- 4.4 for VN neurons. Our findings suggest that substantial pooling and/or selective decoding of vestibular signals from the vestibular and deep cerebellar nuclei may be important components of further processing. Such a characterization of neural sensitivity is critical for understanding how early stages of vestibular processing limit behavioral performance. PMID:20071508

  16. Developmental tightening of cerebellar cortical synaptic influx-release coupling.

    PubMed

    Baur, David; Bornschein, Grit; Althof, Daniel; Watanabe, Masahiko; Kulik, Akos; Eilers, Jens; Schmidt, Hartmut

    2015-02-01

    Tight coupling between Ca(2+) channels and the sensor for vesicular transmitter release at the presynaptic active zone (AZ) is crucial for high-fidelity synaptic transmission. It has been hypothesized that a switch from a loosely coupled to a tightly coupled transmission mode is a common step in the maturation of CNS synapses. However, this hypothesis has never been tested at cortical synapses. We addressed this hypothesis at a representative small cortical synapse: the synapse connecting mouse cerebellar cortical parallel fibers to Purkinje neurons. We found that the slow Ca(2+) chelator EGTA affected release significantly stronger at immature than at mature synapses, while the fast chelator BAPTA was similarly effective in both groups. Analysis of paired-pulse ratios and quantification of release probability (pr) with multiple-probability fluctuation analysis revealed increased facilitation at immature synapses accompanied by reduced pr. Cav2.1 Ca(2+) channel immunoreactivity, assessed by quantitative high-resolution immuno-electron microscopy, was scattered over immature boutons but confined to putative AZs at mature boutons. Presynaptic Ca(2+) signals were quantified with two-photon microscopy and found to be similar between maturation stages. Models adjusted to fit EGTA dose-response curves as well as differential effects of the Ca(2+) channel blocker Cd(2+) indicate looser and less homogenous coupling at immature terminals compared with mature ones. These results demonstrate functionally relevant developmental tightening of influx-release coupling at a single AZ cortical synapse and corroborate developmental tightening of coupling as a prevalent phenomenon in the mammalian brain. PMID:25653347

  17. Impaired modulation of the otolithic function in acute unilateral cerebellar infarction.

    PubMed

    Choi, Seo Young; Lee, Seung-Han; Kim, Hyo Jung; Kim, Ji-Soo

    2014-06-01

    To define the cerebellar contribution in modulating the otolithic signals, we investigated the otolithic function in 27 patients with acute unilateral cerebellar infarctions in the territory of the posterior inferior cerebellar artery (PICA, n?=?17, 63%), combined PICA and superior cerebellar artery (SCA) (n?=?7, 30%), SCA (n?=?2, 7%), and anterior inferior cerebellar artery (n?=?1, 4%) from 2010 to 2012. The patients had evaluation of the ocular tilt reaction [head tilt, ocular torsion (OT), and skew deviation], tilt of the subjective visual vertical (SVV), cervical vestibular evoked myogenic potentials (VEMPs) in response to air conducted tone bursts, and ocular VEMPs induced by tapping the head at AFz. The evaluation was completed within 2 weeks after symptom onset. Patients often showed OT or SVV tilt (15/27, 55.6%) that was either ipsi- (n?=?6) or contraversive (n?=?9). Overall, there were no differences in the amplitudes and latencies of cervical and ocular VEMPs between the ipsi- and contralesional sides. However, individual analyses revealed frequent abnormalities of cervical (11/27, 41%) and/or ocular (9/27, 33%) VEMPs. While 11 (73%) of the 15 patients with the OTR/SVV tilt showed abnormalities of cervical (n?=?9) and/or ocular (n?=?7) VEMP responses, only three (25%) of the 12 patients without the OTR/SVV tilt had abnormal cervical (n?=?2) and/or ocular (n?=?2) VEMPs (73% vs. 25%, Fisher's exact test, p?=?0.021). The concordance rate in the results of cervical and ocular VEMPs was marginally significant (19/27, 70%, p?=?0.052, binominal). Unilateral cerebellar lesions may generate otolithic imbalances, as evidenced by the OTR/SVV tilt and asymmetric ocular or cervical VEMP responses, but without directionality according to the lesion side. Patients with the OTR/SVV tilt had abnormal VEMPs more often than those without. PMID:24390864

  18. Automated cerebellar segmentation: Validation and application to detect smaller volumes in children prenatally exposed to alcohol?

    PubMed Central

    Cardenas, Valerie A.; Price, Mathew; Infante, M. Alejandra; Moore, Eileen M.; Mattson, Sarah N.; Riley, Edward P.; Fein, George

    2014-01-01

    Objective To validate an automated cerebellar segmentation method based on active shape and appearance modeling and then segment the cerebellum on images acquired from adolescents with histories of prenatal alcohol exposure (PAE) and non-exposed controls (NC). Methods Automated segmentations of the total cerebellum, right and left cerebellar hemispheres, and three vermal lobes (anterior, lobules I–V; superior posterior, lobules VI–VII; inferior posterior, lobules VIII–X) were compared to expert manual labelings on 20 subjects, studied twice, that were not used for model training. The method was also used to segment the cerebellum on 11 PAE and 9 NC adolescents. Results The test–retest intraclass correlation coefficients (ICCs) of the automated method were greater than 0.94 for all cerebellar volume and mid-sagittal vermal area measures, comparable or better than the test–retest ICCs for manual measurement (all ICCs > 0.92). The ICCs computed on all four cerebellar measurements (manual and automated measures on the repeat scans) to compare comparability were above 0.97 for non-vermis parcels, and above 0.89 for vermis parcels. When applied to patients, the automated method detected smaller cerebellar volumes and mid-sagittal areas in the PAE group compared to controls (p < 0.05 for all regions except the superior posterior lobe, consistent with prior studies). Discussion These results demonstrate excellent reliability and validity of automated cerebellar volume and mid-sagittal area measurements, compared to manual measurements. These data also illustrate that this new technology for automatically delineating the cerebellum leads to conclusions regarding the effects of prenatal alcohol exposure on the cerebellum consistent with prior studies that used labor intensive manual delineation, even with a very small sample. PMID:25061566

  19. Crossed Cerebellar Diaschisis in Acute Stroke Detected by Dynamic Susceptibility Contrast MR Perfusion Imaging

    PubMed Central

    Lin, D.D.M.; Kleinman, J.T.; Wityk, R.J.; Gottesman, R.F.; Hillis, A.E.; Lee, A.W.; Barker, P.B.

    2010-01-01

    BACKGROUND AND PURPOSE Crossed cerebellar diaschisis (CCD), the decrease in blood flow and metabolism in the cerebellar hemisphere contralateral to a supratentorial stroke, is frequently reported on positron-emission tomography (PET) and single-photon emission CT (SPECT) but is rarely described with MR perfusion techniques. This study was undertaken to determine the frequency of CCD observed in acute stroke by retrospective review of a research data base of patients with acute stroke evaluated by diffusion-weighted (DWI) and dynamic contrast susceptibility perfusion MR imaging (PWI). MATERIALS AND METHODS PWI scans of 301 consecutive patients with acute stroke and positive DWI abnormality from a research data base were reviewed. Contralateral cerebellar hypoperfusion was identified by inspection of time-to-peak (TTP) maps for asymmetry with an absence of cerebellar abnormalities on T2-weighted scans, DWI, or disease of the vertebrobasilar system on MR angiography. In a subset of the cases, quantitative analysis of perfusion scans was performed using an arterial input function and singular value decomposition (SVD) to generate cerebral blood flow (CBF) maps. RESULTS A total of 47 of 301 cases (15.61%) met the criteria of CCD by asymmetry of cerebellar perfusion on TTP maps. On quantitative analysis, there was corresponding reduction of CBF by 22.75 ± 10.94% (range, 7.45% to 52.13%) of the unaffected cerebellar hemisphere). CONCLUSION MR perfusion techniques can be used to detect CCD, though the frequency presented in this series is lower than that commonly reported in the PET/SPECT literature. Nevertheless, with its role in acute stroke and noninvasive nature, MR perfusion may be a viable alternative to PET or SPECT to study the phenomenon and clinical consequences of supratentorial stroke with CCD. PMID:19193758

  20. Cerebellar long-term depression requires dephosphorylation of TARP in Purkinje cells.

    PubMed

    Nomura, Toshihiro; Kakegawa, Wataru; Matsuda, Shinji; Kohda, Kazuhisa; Nishiyama, Jun; Takahashi, Takao; Yuzaki, Michisuke

    2012-02-01

    Cerebellar long-term depression (LTD) at parallel fiber (PF)-Purkinje cell synapses is thought to play an essential role in certain forms of motor learning. Like hippocampal LTD, cerebellar LTD is mediated by the endocytosis of AMPA (?-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate) receptors at postsynaptic sites. However, similar sets of kinases and phosphatases have opposite regulatory effects on hippocampal and cerebellar LTD, although the mechanisms responsible for this difference remain largely unclear. Activity-dependent dephosphorylation of stargazin (an AMPA receptor auxiliary protein) by calcineurin regulates hippocampal LTD, but whether and how stargazin is involved in cerebellar LTD is unknown. In this study, we showed that stargazin is highly phosphorylated at basal states and is dephosphorylated by the application of high KCl plus glutamate (K-glu) or of a metabotropic glutamate receptor agonist, (S)-3,5-dihydroxyphenylglycine (DHPG), both of which chemically induced LTD in cerebellar slices. This chemically induced dephosphorylation of stargazin was specifically blocked by a calcineurin inhibitor. Indeed, inclusion of the calcineurin auto-inhibitory peptide in the patch pipette solution completely inhibited the LTD induced by the conjunctive stimulation of PFs and Purkinje cells. Furthermore, in Purkinje cells expressing stargazin-9D, in which all nine serine residues are mutated to aspartate, neither conjunctive stimulus nor DHPG treatment induced LTD. Finally, immunohistochemical analyses revealed that neither K-glu nor DHPG induced the endocytosis of AMPA receptors in Purkinje cells expressing stargazin-9D. Together, these results indicate that hippocampal and cerebellar LTD share a common pathway, namely dephosphorylation of stargazin by calcineurin. PMID:22239345

  1. Acute neuronal and vascular changes following unilateral cerebellar pedunculotomy in the neonatal rat

    PubMed Central

    SHERRARD, RACHEL M.; BOWER, ADRIAN J.

    1997-01-01

    During development of the central nervous system (CNS) both deafferentation and axotomy induce increased neuronal death and result in a smaller brain with diminished function at maturity. Unilateral cerebellar pedunculotomy has been used as a model to study the relative importance of these 2 types of lesion on the survival of developing CNS neurons. Within the cerebellum, unilateral pedunculotomy causes deafferentation of the hemicerebellum and axotomy in the efferent pathway from the ipsilateral deep cerebellar nuclei. This results in a smaller hemicerebellum with normal cortical laminae but no extracerebellar outflow. In order to identify the sequence of events which leads to this altered structure and therefore to understand the relative importance of afferent versus target-derived trophic support, unilateral cerebellar pedunculotomy was performed on neonatal rat pups, aged between 1 and 3 days. The cerebella were analysed for histological and vascular changes after survival times of 0, 3, 6, 9, 12, 18, 21, 24 and 48 h. The results show that the effects of axotomy on the deep cerebellar nuclear neurons begin within 3 h of the lesion and apoptotic neuronal degeneration occurs within 48 h. However, the cerebellar cortical neurons continue to undergo normal histological development for at least 48 h after deafferentation. In addition, since ischaemia induces similar effects, a study of the vascular tree was made. The results indicate that the pedunculotomy does not alter the blood supply to the cerebellum, nor induce ischaemia of the cerebellar neurons. From this it may be hypothesised that target-derived trophic support is more crucial for the survival of immature neurons than is the trophic effect of afferent input. PMID:9306195

  2. Huge arachnoid cyst of the posterior fossa with cerebellar tentorium dysplasia associated with juvenile polyposis.

    PubMed

    Sugata, Sei; Niiro, Masaki; Tanioka, Kouji; Yano, Tsunehiro; Kuratsu, Jun-Ichi

    2003-05-01

    We report an infant with a huge arachnoid cyst of the posterior fossa with dysplasia of the cerebellar tentorium and meningeal sinus and associated juvenile polyposis. Neuroimaging studies disclosed a huge median cystic lesion extending posterosuperiorly over the cerebellum. The cerebellar tentorium was raised to the parietal area; the vermis was normoplastic. Cystography showed no direct communication with the 4th ventricle or subarachnoid space. We discuss the differential diagnosis of median cysts of the posterior fossa and the association of juvenile polyposis. PMID:12686769

  3. Preoperative embolization of a cerebellar haemangioblastoma using Onyx: case report and literature review.

    PubMed

    Seong Eom, Ki; Won Kim, Dae; Sung Choi, See; Ha Choi, Keum; Young Kim, Tae

    2011-01-01

    Haemangioblastoma is a slow-growing, highly vascular tumour and typically occurs in the cerebellum but can also occur in the brainstem and spinal cord. Because of their hypervascularity and location, cerebellar haemangioblastomas can be difficult to remove. The purpose of preoperative embolization of haemangioblastomas is to decrease the intraoperative blood loss and to facilitate excision. However, the safety and efficacy of this procedure remain controversial. Here, we report the case of a man with cerebellar haemangioblastoma who underwent preoperative embolization with Onyx. The tumour was completely removed with minimal tumour bleeding. There was no complication related to embolization. PMID:21866486

  4. Bihemispheric Posterior Inferior Cerebellar Artery Occurring with an Azygos Anterior Cerebral Artery: Case Study

    PubMed Central

    Wadhwa, Rishi

    2014-01-01

    Variations in intracranial vasculature are well known. We report a rare anatomic variation in a patient who underwent cerebral angiography for suspected intracranial aneurysm. Digital subtraction angiography revealed a bihemispheric posterior inferior cerebellar artery (PICA) and an azygous anterior cerebral artery (ACA). There was no evidence of any aneurysm or vascular abnormality. To our knowledge, this is the first reported case of a patient with a common PICA supplying both the cerebellar hemispheres and a common ACA supplying ACA territory bilaterally. It is important for the physician to be aware of these anatomical variations in order to differentiate a normal variant from a pathological condition. PMID:24955276

  5. Hemifacial Spasm Caused by Fusiform Aneurysm at Vertebral Artery-Posterior Inferior Cerebellar Artery Junction

    PubMed Central

    Choi, Seok-Keun; Park, Bong-Jin; Lim, Young-Jin

    2008-01-01

    Hemifacial spasm induced by intracranial aneurysm is a rare clinical condition. A 45-year-old male patient presented with a 3-year history of progressive involuntary twitching movement on right face. On radiological study, a dilated vascular lesion compressing the brain stem was found at the junction of vertebral artery and posterior inferior cerebellar artery. On operative field, we found the posterior inferior cerebellar artery and the fusiform aneurysm compressing root exit zone of facial nerve. Microvascular decompression was performed and the facial symptom was relieved without complications. PMID:19137088

  6. [The tumoral form of cerebellar schistosomiasis: case report and measure of granulomas].

    PubMed

    Raso, Pedro; Tafuri, Alexandre; Lopes, Ney da Fonseca; Monteiro, Eduardo Rossi; Tafuri, Wagner Luiz

    2006-01-01

    An unusual case of the tumoral form of cerebellar Schistosomiasis mansoni, in a 15 year-old male diagnosed by biopsy, with neurological signs and symptoms 60 days prior to surgery. Computerized tomography show a hyperdense expanding lesion located in cerebellum, suggesting glioma. Histopathological examination showed numerous S. mansoni ova involved by granulomatous inflammation in necrotic-exudative phase, located mainly in the internal, granular layer of the cerebellum, creating a pseudotumor in the cerebellar vermis and a recent hemorrhage in the trunk. The areas of granulomas were measured. PMID:16906255

  7. Neuropsychological evaluation in an adolescent with cerebellar hypoplasia diagnosed with Asperger's Syndrome.

    PubMed

    Moss, Robert A

    2013-01-01

    There is a growing body of literature describing cases of cognitive impairment associated with both acquired and developmental damage to the cerebellum. The current case study describes such a case involving a 17-year-old male with cerebellar hypoplasia, having incomplete formation of the vermis and atrophy of the interior cerebellar hemispheres. He had previously been diagnosed as having Asperger's Syndrome. A full neuropsychological evaluation was performed, including effort testing. This is followed by a comparison of the current results to previously reported cases, with a discussion of the heterogeneity of deficits associated with developmental cerebellum malformation. PMID:22506855

  8. Dysplastic cerebellar gangliocytoma lhermitte-duclos disease imaging and magnetic resonance spectroscopy.

    PubMed

    Fauria-Robinson, Christian; Nguyen, Jeremy; Palacios, Enrique; Castillo-Jorge, Sarah

    2014-01-01

    Lhermitte-Duclos disease (LDD) is a rare, benign, slow-growing, unilateral mass of the cerebellar cortex. Our case is that of a 71-year-old male with a superior cerebellar lesion consistent with LDD on imaging and Magnetic Resonance Spectroscopy (MRS). It has been reported that MRS can be a valuable diagnostic addition, as it allows for a non-invasive diagnosis and analysis to distinguish a benign lesion, such as an intraparenchymal lesion, and in our case, from a true neoplastic lesion. PMID:25369219

  9. Assessing a dysplastic cerebellar gangliocytoma (Lhermitte-Duclos disease) with 7T MR imaging.

    PubMed

    Moenninghoff, Christoph; Kraff, Oliver; Schlamann, Marc; Ladd, Mark E; Katsarava, Zaza; Gizewski, Elke R

    2010-01-01

    Lhermitte-Duclos disease (LDD; dysplastic cerebellar gangliocytoma) is a rare hamartomatous lesion of the cerebellar cortex and this was first described in 1920. LDD is considered to be part of the autosomal-dominant phacomatosis and cancer syndrome Cowden disease (CS). We examined the brain of a 46-year-old man, who displayed the manifestations of CS, with 7 Tesla (T) and 1.5 T MRI and 1.5 T MR spectroscopy (1H-MRS). We discuss the possible benefits of employing ultrahigh-field MRI for making the diagnosis of this rare lesion. PMID:20191074

  10. The effect of cyclic phosphatidic acid on the proliferation and differentiation of mouse cerebellar granule precursor cells during cerebellar development.

    PubMed

    Konakazawa, Misa; Gotoh, Mari; Murakami-Murofushi, Kimiko; Hamano, Ayana; Miyamoto, Yasunori

    2015-07-21

    The proliferation and differentiation of cerebellar granule cell precursors (GCPs) are highly regulated spatiotemporally during development. We focused on cyclic phosphatidic acid (cPA) as a lipid mediator with a cyclic phosphate group as a regulatory factor of GCPs. While its structure is similar to that of lysophosphatidic acid (LPA), its function is very unique. cPA is known to be present in the cerebellum at high levels, but its function has not been fully elucidated. In this study, we examined the role of cPA on the proliferation and differentiation of GCPs. A cell cycle analysis of GCPs revealed that cPA reduced the number of phospho-histone H3 (Phh3)-positive cells and bromodeoxy uridine (BrdU)-incorporated cells and increased an index of the cell cycle exit. We next analyzed the effect of cPA on GCP differentiation using Tuj1 as a neuronal marker of final differentiation. The results show that cPA increased the number of Tuj1-positive cells. Further analysis of the proliferation of GCPs showed that cPA suppressed Sonic hedgehog (Shh)-dependent proliferation, but did not suppress insulin-like growth factor-1 (IGF-1)-dependent proliferation. P2Y5 (LPA6), an LPA receptor, is highly expressed in GCPs. The knockdown of P2Y5 suppressed the inhibitory effect of cPA on the proliferation of GCPs, suggesting that P2Y5 is a candidate receptor for cPA. Thus, cPA suppresses the Shh-dependent proliferation of GCPs and promotes the differentiation of GCPs through P2Y5. These results demonstrate that cPA plays a critical role in the development of GCPs. PMID:25896936

  11. 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…

  12. 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.…

  13. Fast Descent Methods for LPs With Minimal or No Matrix Katta G. Murty

    E-print Network

    Murty, Katta G.

    Fast Descent Methods for LPs With Minimal or No Matrix Inversions Katta G. Murty Department Programming (LP), Interior point methods (IPMs) , ball centers of a polytope, solving LPs using matrix inversions sparingly, Sphere methods-1, 2, 2.1, 3, 4 for large scale LPs. 1 Introduction For modeling

  14. 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

  15. Job Satisfaction of Librarians of African Descent Employed in ARL Academic Libraries.

    ERIC Educational Resources Information Center

    Thornton, Joyce K.

    2000-01-01

    Examines job satisfaction of librarians of African descent employed at academic libraries who are members of the Association of Research Libraries (ARL). Presents results of a three-part job satisfaction survey that identifies areas of satisfaction and dissatisfaction and discusses the need to recruit and retain a diverse workforce. (Contains 38…

  16. 3D HAND TRACKING BY RAPID STOCHASTIC GRADIENT DESCENT USING A SKINNING MODEL

    Microsoft Academic Search

    Matthieu Bray; Esther Koller-Meier; Pascal M; Luc Van Gool; Nicol N. Schraudolph

    The main challenge of tracking articulated structures like hands is their large number of degrees of freedom (DOFs). A realistic 3D model of the human hand has at least 26 DOFs. The arsenal of tracking approaches that can track such structures fast and re- liably is still very small. This paper proposes a tracker based on 'Stochastic Meta-Descent' (SMD) for

  17. DESCENT FOR NON-ARCHIMEDEAN ANALYTIC SPACES BRIAN CONRAD AND MICHAEL TEMKIN

    E-print Network

    Conrad, Brian

    .5.7]). In the case of quasi-finite morphisms [Ber2, §3.1], which are maps that are finite locally on the source the definitions since the target of a finite surjective morphism with affinoid source can be non-affinoid [Liu algebraic geometry [CT, §2.1]). Similarly, faithfully flat descent for morphisms, admissible open sets

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

    E-print Network

    of Technology Abstract Previous missions to Mars have landed masses of approximately 1 metric ton on the surface. Vehicles large enough to support humans on the flight to Mars and land them safely on the surface presents the development of a simulation of the descent phase of a manned landing at Mars, an overview

  19. Minimum-Landing-Error Powered-Descent Guidance for Mars Landing Using Convex Optimization

    E-print Network

    Williams, Brian C.

    Minimum-Landing-Error Powered-Descent Guidance for Mars Landing Using Convex Optimization Lars Rovers [2]. The 2009 Mars Science Laboratory mission aims to achieve a landing ellipse of around 10 km [3 to Mars and to enable sample return missions, the accuracy with which a lander can be delivered

  20. The Ordered Subsets Mirror Descent Optimization Method with Applications to Tomography

    E-print Network

    Nemirovski, Arkadi

    of organs and tissues, while other imaging techniques - such as X-ray, computerized tomography (CTThe Ordered Subsets Mirror Descent Optimization Method with Applications to Tomography by Aharon Emission Tomography (PET). A mathematical model of the problem, based on the Maximum Likelihood principle

  1. 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.

  2. Association of polymorphisms of circadian gene, Clock and Clif, withhyperlipidemia in Chinese Han descent

    Microsoft Academic Search

    Yan Zou; Fang Lu; Chen Chen; Zhou Jiang; Suting Cheng; Yanyou Liu; Yuhui Wang; Jing Xiao; Huiling Guo; Zhengrong Wang

    2011-01-01

    Circadian gene, Clock and Clif, not only maintain the circadian rhythm of cells but also regulate lipid and glucose metabolism in peripheral organs. The purpose of this study was to determine whether genetic variations (single nucleotide polymorphisms – SNPs) in the Clock and\\/or Clif genes were associated with hyperlipidemia in Chinese Han descent. The Clock variants (rs3840267, rs3749474, rs1052925) and

  3. Association of polymorphisms of circadian gene, Clock and Clif, with hyperlipidemia in Chinese Han descent

    Microsoft Academic Search

    Yan Zou; Fang Lu; Chen Chen; Zhou Jiang; Suting Cheng; Yanyou Liu; Yuhui Wang; Jing Xiao; Huiling Guo; Zhengrong Wang

    2012-01-01

    Circadian gene, Clock and Clif, not only maintain the circadian rhythm of cells but also regulate lipid and glucose metabolism in peripheral organs. The purpose of this study was to determine whether genetic variations (single nucleotide polymorphisms – SNPs) in the Clock and\\/or Clif genes were associated with hyperlipidemia in Chinese Han descent. The Clock variants (rs3840267, rs3749474, rs1052925) and

  4. A Terminal Descent Sensor Trade Study Overview for the Orion Landing and Recovery System

    NASA Technical Reports Server (NTRS)

    Dunn, Catherine; Prakash, Ravi

    2008-01-01

    This trade study was conducted as a part of the Orion Landing System Advanced Development Project to determine possible Terminal Descent Sensor (TDS) architectures that could be used for a rocket assisted landing system. Several technologies were considered for the Orion TDS including radar, lidar, GPS applications, mechanical sensors, and gamma ray altimetry.

  5. Accelerated Haptic Rendering of Polygonal Models through Local Descent David E. Johnson and Peter Willemsen

    E-print Network

    Utah, University of

    Accelerated Haptic Rendering of Polygonal Models through Local Descent David E. Johnson and Peter Willemsen School of Computing, University of Utah Abstract In a prior paper, we described a haptic rendering algorithm for arbitrary polygonal models using a six degree-of-freedom haptic interface. In that paper

  6. 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…

  7. ECE 174 Lecture Supplement SPRING 2009 Gradient-Descent GPS Algorithms

    E-print Network

    Wang, Deli

    . The (constant) systematic clock bias error b is caused by an inaccurate clock in the GPS receiver. The sameECE 174 ­ Lecture Supplement ­ SPRING 2009 Gradient-Descent GPS Algorithms Kenneth Kreutz ECE174LS-GPS-S09v1.0 Copyright c 2002-09, All Rights Reserved May 20, 2009 Linearization of the True

  8. Meteorological Predictions in Support of the Mars Science Laboratory Entry, Descent and Landing

    Microsoft Academic Search

    A. Rothchild; S. C. Rafkin; R. A. Pielke Sr.

    2010-01-01

    The Mars Science Laboratory (MSL) entry, descent, and landing (EDL) system employs a standard parachute strategy followed by a new sky crane concept where the rover is lowered to the ground via a tether from a hovering entry vehicle. As with previous missions, EDL system performance is sensitive to atmospheric conditions. While some observations characterizing the mean, large-scale atmospheric temperature

  9. Space-Based Nonlinear Dynamic Inversion Control for Aircraft Continuous Descent Approach

    E-print Network

    Paris-Sud XI, Université de

    Space-Based Nonlinear Dynamic Inversion Control for Aircraft Continuous Descent Approach Hakim and safety in flight operations. This communi- cation proposes a new representation of aircraft flight aircraft. The main novelty is that the adopted independent variable is the distance to land. This new

  10. 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.

  11. Understanding Language Socialization and Learning in Mexican-Descent Families: Conclusions and New Directions.

    ERIC Educational Resources Information Center

    Moreno, Robert P.; Perez-Granados, Deanne R.

    2002-01-01

    Compares findings from the six studies in this special journal issue, focusing on the role of Mexican-descent family conversations in young children's social, emotional, and conceptual development and on patterns of maternal teaching behaviors across socioeconomic backgrounds. Discusses the need for further research that represents the diversity…

  12. Parents and Siblings As Early Resources for Young Children's Learning in Mexican-Descent Families.

    ERIC Educational Resources Information Center

    Perez-Granados, Deanne R.; Callanan, Maureen A.

    1997-01-01

    Interviews with parents from 50 Mexican-descent families revealed that parents encouraged their preschool children to ask questions about science and causal relationships; older and younger siblings learned different skills from one another; and children learned through observation and imitation. Discusses issues of "match" between home and school…

  13. Links to the Past Genealogy is the study of the descent of families and persons

    E-print Network

    Thompson, Michael

    Genealogy: Links to the Past #12;Genealogy is the study of the descent of families and persons fromWhy do people become involved in genealogy?in genealogy? Interested in where they come from Health issues for beginners. Many of the large genealogy websites provide advice, tutorials and record forms for those just

  14. 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

  15. 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.)…

  16. Parents' Science Talk to Their Children in Mexican-Descent Families Residing in the USA

    ERIC Educational Resources Information Center

    Tenenbaum, Harriet R.; Callanan, Maureen A.

    2008-01-01

    Everyday parent-child conversations may support children's scientific understanding. The types and frequency of parent-child science talk may vary with the cultural and schooling background of the participants, and yet most research in the USA focuses on highly schooled European-American families. This study investigated 40 Mexican-descent

  17. Use of steepest descent and various approximations for efficient computation of minimum noise aircraft landing trajectories

    NASA Technical Reports Server (NTRS)

    Cook, G.; Witt, R. M.

    1976-01-01

    The following areas related to landing trajectory optimization research were discussed: (1) programming and modifying the steepest descent optimization procedure, (2) successfully iterating toward the optimum for a four-mile trajectory, (3) beginning optimization runs for a twenty-mile trajectory, and (4) adapt wind tunnel data for computer usage. Other related areas were discussed in detail in the two previous annual reports.

  18. Fast Bounded Online Gradient Descent Algorithms for Scalable Kernel-Based Online Learning

    E-print Network

    Jin, Rong

    Fast Bounded Online Gradient Descent Algorithms for Scalable Kernel-Based Online Learning Peilin University, USA Abstract Kernel-based online learning has often shown state-of-the-art performance for many online learning tasks. It, however, suffers from a major shortcoming, that is, the unbounded number

  19. Hybrid Entry Ship: A Conceptual Entry-Descent and Surveillance Platform for Venus Atmosphere

    NASA Astrophysics Data System (ADS)

    Alam, Mr.; Saroha, Mr.; Priyadarshi, Mr.; Limaye, Mr.

    2015-04-01

    A hybrid entry ship concept which will enter from low Venus orbit. It will undergo series of changes in its configuration to meet an optimal entry-descent and surveillance sequence. It houses payloads upto 300 kg. Available power to payload is 250W.

  20. A Survey of Supersonic Retropropulsion Technology for Mars Entry, Descent, and Landing

    Microsoft Academic Search

    Ashley M. Korzun; Juan R. Cruz; Robert D. Braun

    2008-01-01

    This paper presents a literature survey on supersonic retropropulsion technology as it applies to Mars entry, descent, and landing (EDL). The relevance of this technology to the feasibility of Mars EDL is shown to increase with ballistic coefficient to the point that it is likely required for human Mars exploration. The use of retropropulsion to decelerate an entry vehicle from

  1. Efficient neuro-fuzzy rule generation by parametrized gradient descent for seismic event discrimination

    Microsoft Academic Search

    F. Gravot; J. D. Muller; S. Muller

    1999-01-01

    We show that parametrized gradient descent is very efficient to train fuzzy expert systems with examples. We first present how fuzzy expert systems work and explain their relevance compared to neural classifiers. Then, we describe the proposed learning algorithm. We further explain in more detail its application in each parameter of the fuzzy expert system: the position and the width

  2. Mathematical relationships between uterine contractions, cervical dilatation, descent and rotation in spontaneous vertex deliveries

    Microsoft Academic Search

    H. N Sallam; A Abdel-Dayem; R. A Sakr; A Sallam; I Loutfy

    1999-01-01

    Objective: To determine the mathematical relationships between the strength and duration of the uterine contractions, the descent and rotation of the fetal head and the degree of cervical dilatation in 50 multiparous women with spontaneous vaginal deliveries using a simple device applied to the fetal vertex. Method: A simple device for monitoring the progress of labor was applied to the

  3. Full convergence of the steepest descent method with inexact line searches

    Microsoft Academic Search

    Regina Burachik; Luis Mauricio; Grana Drummond; Alfredo N. Iusem

    1996-01-01

    Several finite procedures for determining the step size of the steepest descent method for uncon- strained optimization, without performing exact onedimensional minimizations, have been consid- ered in the literature. The convergence analysis of these methods requires that the objective function have bounded level sets and that its gradient satisfy a Lipschitz condition, in order to establish just stationarity of all

  4. A Numerical Descent Method for an Inverse Problem of a Scalar Conservation Law

    E-print Network

    Sepúlveda, Mauricio

    A Numerical Descent Method for an Inverse Problem of a Scalar Conservation Law Modelling and numerical methods for inverse problems in nonlinear hyperbolic PDEs; see for instance [11, 12, 15 conservation law when the solution at a fixed time is known. This problem occurs in a model of batch

  5. Joint inference of identity by descent along multiple chromosomes from population samples

    E-print Network

    Washington at Seattle, University of

    words: Latent identity by descent; shared genome segments; linkage disequilibrium; hidden Markov model among sets of four haplotypes. Our new IBD detection method focuses on the scale between genome-wide methods using simple IBD models and complex coalescent-based methods which are limited to short genome

  6. A study on the optimal double parameters for steepest descent with momentum.

    PubMed

    Zhang, Naimin

    2015-04-01

    This letter presents the stability analysis for two steepest descent algorithms with momentum for quadratic functions. The corresponding local optimal parameters in Torii and Hagan ( 2002 ) and Zhang ( 2013 ) are extended to the global optimal parameters, that is, both the optimal learning rates and the optimal momentum factors are obtained simultaneously which make for the fastest convergence. PMID:25602771

  7. Transformation of the cerebellum into more ventral brainstem fates causes cerebellar agenesis in the absence of Ptf1a function.

    PubMed

    Millen, Kathleen J; Steshina, Ekaterina Y; Iskusnykh, Igor Y; Chizhikov, Victor V

    2014-04-29

    Model organism studies have demonstrated that cell fate specification decisions play an important role in normal brain development. Their role in human neurodevelopmental disorders, however, is poorly understood, with very few examples described. The cerebellum is an excellent system to study mechanisms of cell fate specification. Although signals from the isthmic organizer are known to specify cerebellar territory along the anterior-posterior axis of the neural tube, the mechanisms establishing the cerebellar anlage along the dorsal-ventral axis are unknown. Here we show that the gene encoding pancreatic transcription factor PTF1A, which is inactivated in human patients with cerebellar agenesis, is required to segregate the cerebellum from more ventral extracerebellar fates. Using genetic fate mapping in mice, we show that in the absence of Ptf1a, cells originating in the cerebellar ventricular zone initiate a more ventral brainstem expression program, including LIM homeobox transcription factor 1 beta and T-cell leukemia homeobox 3. Misspecified cells exit the cerebellar anlage and contribute to the adjacent brainstem or die, leading to cerebellar agenesis in Ptf1a mutants. Our data identify Ptf1a as the first gene involved in the segregation of the cerebellum from the more ventral brainstem. Further, we propose that cerebellar agenesis represents a new, dorsal-to-ventral, cell fate misspecification phenotype in humans. PMID:24733890

  8. Detection of sequences in the cerebellar cortex: numerical estimate of the possible number of tidal-wave inducing sequences represented.

    PubMed

    Sultan, Fahad; Heck, Detlef

    2003-01-01

    The two major cortices of the brain--the cerebral and cerebellar cortex--are massively connected through intercalated nuclei (pontine, cerebellar and thalamic nuclei). We suggest that the two cortices co-operate by generating precise temporal patterns in the cerebral cortex that are detected in the cerebellar cortex as temporal patterns assembled spatially in the mossy fibers. We will begin by showing that the tidal-wave mechanism works in the cerebellar cortex as a read-out mechanism for such spatio-temporal patterns due to the synchronous activity they generate in the parallel fiber system which drives the Purkinje cells--the output neurons of the cerebellar cortex--to fire action potentials. We will review the anatomy of the mossy fibers and show that within a "beam", or "row" of cerebellar cortex the mossy fibers in principle could embed a vast number of tidal-wave generating sequences. Based on anatomical data we will argue that the cerebellar mossy fiber-granule cell-Purkinje cell system can potentially detect and--through learning--select from an enormous number of spatio-temporal patterns. PMID:15242668

  9. Transformation of the cerebellum into more ventral brainstem fates causes cerebellar agenesis in the absence of Ptf1a function

    PubMed Central

    Millen, Kathleen J.; Steshina, Ekaterina Y.; Iskusnykh, Igor Y.; Chizhikov, Victor V.

    2014-01-01

    Model organism studies have demonstrated that cell fate specification decisions play an important role in normal brain development. Their role in human neurodevelopmental disorders, however, is poorly understood, with very few examples described. The cerebellum is an excellent system to study mechanisms of cell fate specification. Although signals from the isthmic organizer are known to specify cerebellar territory along the anterior–posterior axis of the neural tube, the mechanisms establishing the cerebellar anlage along the dorsal–ventral axis are unknown. Here we show that the gene encoding pancreatic transcription factor PTF1A, which is inactivated in human patients with cerebellar agenesis, is required to segregate the cerebellum from more ventral extracerebellar fates. Using genetic fate mapping in mice, we show that in the absence of Ptf1a, cells originating in the cerebellar ventricular zone initiate a more ventral brainstem expression program, including LIM homeobox transcription factor 1 beta and T-cell leukemia homeobox 3. Misspecified cells exit the cerebellar anlage and contribute to the adjacent brainstem or die, leading to cerebellar agenesis in Ptf1a mutants. Our data identify Ptf1a as the first gene involved in the segregation of the cerebellum from the more ventral brainstem. Further, we propose that cerebellar agenesis represents a new, dorsal-to-ventral, cell fate misspecification phenotype in humans. PMID:24733890

  10. Spatial navigation impairment in mice lacking cerebellar LTD: a motor adaptation deficit?

    E-print Network

    Paris-Sud XI, Université de

    1 Spatial navigation impairment in mice lacking cerebellar LTD: a motor adaptation deficit? Eric University of Medical Sciences, IRAN & Current address: Neuroscience Group, Sony Computer Science Laboratory and procedural components of spatial navigation. Our data bring evidence for a deficit of L7-PKCI mice

  11. Severe alterations of cerebellar cortical development after constitutive activation of Wnt signaling in granule neuron precursors.

    PubMed

    Lorenz, Andreas; Deutschmann, Markus; Ahlfeld, Julia; Prix, Catharina; Koch, Arend; Smits, Ron; Fodde, Riccardo; Kretzschmar, Hans A; Schüller, Ulrich

    2011-08-01

    The Wnt/?-catenin signaling pathway plays crucial roles in early hindbrain formation, and its constitutive activity is associated with a subset of human medulloblastoma, a malignant childhood tumor of the posterior fossa. However, the precise function of Wnt/?-catenin signaling during cerebellar development is still elusive. We generated Math1-cre::Apc(Fl/Fl) mice with a conditional knockout for the Adenomatosis polyposis coli (Apc) gene that displayed a constitutive activity of Wnt/?-catenin signaling in cerebellar granule neuron precursors. Such mice showed normal survival without any tumor formation but had a significantly smaller cerebellum with a complete disruption of its cortical histoarchitecture. The activation of the Wnt/?-catenin signaling pathway resulted in a severely inhibited proliferation and premature differentiation of cerebellar granule neuron precursors in vitro and in vivo. Mutant mice hardly developed an internal granular layer, and layering of Purkinje neurons was disorganized. Clinically, these mice presented with significantly impaired motor coordination and ataxia. In summary, we conclude that cerebellar granule neurons essentially require appropriate levels of Wnt signaling to balance their proliferation and differentiation. PMID:21690300

  12. Sequence Learning is Preserved in Individuals with Cerebellar Degeneration when the Movements are Directly Cued

    Microsoft Academic Search

    Rebecca M. C. Spencer; Richard B. Ivry

    2009-01-01

    Cerebellar pathology is associated with impairments on a range of motor learning tasks including sequence learning. However, various lines of evidence are at odds with the idea that the cerebellum plays a central role in the associative processes underlying sequence learning. Behavioral studies indicate that sequence learning, at least with short periods of practice, involves the establishment of effector-independent, spatial

  13. Cerebellar Volume and Cognitive Functioning in Children Who Experienced Early Deprivation

    E-print Network

    Wisconsin at Madison, University of

    of the cerebellum have a significant role in cognition and learning (1­7). Still, relatively little is known aboutCerebellar Volume and Cognitive Functioning in Children Who Experienced Early Deprivation Patrick M: The cerebellum is a brain region recognized primarily in the coordination of movement and related accessory motor

  14. CEREBELLAR HYPOPLASIA IN THE GUNN RAT IS ASSOCIATED WITH QUANTITATIVE CHANGES IN NEUROTYPIC AND GLIOTYPIC PROTEINS

    EPA Science Inventory

    The authors are characterizing toxicant-induced injury to the nervous system by measuring nervous system cell-type specific proteins together with accompanying changes in morphology and behavior. In the present study, cerebellar neurotoxicity was assessed in the Gunn rat an autos...

  15. Sporadic Creutzfeldt–Jakob disease with cerebellar ataxia at onset in the UK

    PubMed Central

    Cooper, S A; Murray, K L; Heath, C A; Will, R G; Knight, R S G

    2006-01-01

    Objective To determine the frequency, in the UK, of sporadic Creutzfeldt–Jakob Disease (sCJD) with a cerebellar ataxic onset, and to describe the clinical features of the syndrome. Methods A retrospective review of autopsy?proved cases of sCJD cases in the UK, 1990–2005, identifying those presenting with cerebellar features without early cognitive decline. Results 29 of 618 (5%) patients with sCJD had an isolated cerebellar onset. Mean illness duration was 9?months. Subsequently, 21 (72%) developed myoclonus and 23 (79%) developed pyramidal features. Magnetic resonance imaging showed high signal in the basal ganglia in 11 of 14 (79%) patients. 7 of 15 (47%) patients were valine homozygotic at prion protein gene (PRNP)?129. Only 8 (28%) cases were referred to the surveillance unit after death. Conclusion A better definition of sCJD presenting with an isolated cerebellar syndrome might improve future case recognition and contribute to the determination of its cause. PMID:16835290

  16. MRI evidence of cerebellar and hippocampal involvement in Creutzfeldt-Jakob disease

    Microsoft Academic Search

    M. A. Poon; S. Stuckey; E. Storey

    2001-01-01

    We report a 51-year-old woman with the Brownell-Oppenheimer (cerebellar) variant of Creutzfeldt-Jakob disease (CJD). She\\u000a had the typical findings of bilateral basal ganglion changes on MRI, as well as changes in the cerebellum and hippocampus.\\u000a This case adds further information to the known imaging characteristics of CJD.

  17. MRI evidence of cerebellar and hippocampal involvement in Creutzfeldt-Jakob disease.

    PubMed

    Poon, M A; Stuckey, S; Storey, E

    2001-09-01

    We report a 51-year-old woman with the Brownell-Oppenheimer (cerebellar) variant of Creutzfeldt-Jakob disease (CJD). She had the typical findings of bilateral basal ganglion changes on MRI, as well as changes in the cerebellum and hippocampus. This case adds further information to the known imaging characteristics of CJD. PMID:11594424

  18. Cerebellar Alterations and Gait Defects as Therapeutic Outcome Measures for Enzyme Replacement Therapy in ?-Mannosidosis

    PubMed Central

    Damme, Markus; Stroobants, Stijn; Walkley, Steven U.; Lüllmann-Rauch, Renate; D`Hooge, Rudi; Fogh, Jens; Saftig, Paul; Lübke, Torben; Blanz, Judith

    2011-01-01

    ?-Mannosidosis is a rare lysosomal storage disease with accumulation of undegraded mannosyl-linked oligosaccharides in cells throughout the body, most notably in the CNS. This leads to a broad spectrum of neurological manifestations, including progressive intellectual impairment, disturbed motor functions and cerebellar atrophy. To develop therapeutic outcome measures for enzyme replacement therapy (ERT) that could be used for human patients, a gene knockout model of ?-mannosidosis in mice was analyzed for CNS pathology and motor deficits. In the cerebellar molecular layer, ?-mannosidosis mice display clusters of activated Bergman glia, infiltration of phagocytic macrophages and accumulation of free cholesterol and gangliosides (GM1), notably in regions lacking Purkinje cells. ?-mannosidosis brain lysates also displayed increased expression of Lamp1 and hyperglycosylation of the cholesterol binding protein NPC2. Detailed assessment of motor function revealed age-dependent gait defects in the mice that resemble the disturbed motor function in human patients. Short-term ERT partially reversed the observed cerebellar pathology with fewer activated macrophages and astrocytes but unchanged levels of hyperglycosylated NPC2, gangliosides and cholesterol. The present study demonstrates cerebellar alterations in ?-mannosidosis mice that relate to the motor deficits and pathological changes seen in human patients and can be used as therapeutic outcome measures. PMID:21157375

  19. Mitochondrial Membrane Potential and Glutamate Excitotoxicity in Cultured Cerebellar Granule Cells

    Microsoft Academic Search

    Manus W. Ward; A. Cristina Rego; Bruno G. Frenguelli; David G. Nicholls

    2000-01-01

    The relationship between changes in mitochondrial membrane potential (Dcm) and the failure of cytoplasmic Ca 21 homeostasis, delayed Ca 21deregulation (DCD), is investigated for cultured rat cerebellar granule cells exposed to glutamate. To interpret the single-cell fluorescence response of cells loaded with tetrameth- ylrhodamine methyl ester (TMRM 1) or rhodamine-123, we de- vised and validated a mathematical simulation with well

  20. PMPCA mutations cause abnormal mitochondrial protein processing in patients with non-progressive cerebellar ataxia.

    PubMed

    Jobling, Rebekah K; Assoum, Mirna; Gakh, Oleksandr; Blaser, Susan; Raiman, Julian A; Mignot, Cyril; Roze, Emmanuel; Dürr, Alexandra; Brice, Alexis; Lévy, Nicolas; Prasad, Chitra; Paton, Tara; Paterson, Andrew D; Roslin, Nicole M; Marshall, Christian R; Desvignes, Jean-Pierre; Roëckel-Trevisiol, Nathalie; Scherer, Stephen W; Rouleau, Guy A; Mégarbané, André; Isaya, Grazia; Delague, Valérie; Yoon, Grace

    2015-06-01

    Non-progressive cerebellar ataxias are a rare group of disorders that comprise approximately 10% of static infantile encephalopathies. We report the identification of mutations in PMPCA in 17 patients from four families affected with cerebellar ataxia, including the large Lebanese family previously described with autosomal recessive cerebellar ataxia and short stature of Norman type and localized to chromosome 9q34 (OMIM #213200). All patients present with non-progressive cerebellar ataxia, and the majority have intellectual disability of variable severity. PMPCA encodes ?-MPP, the alpha subunit of mitochondrial processing peptidase, the primary enzyme responsible for the maturation of the vast majority of nuclear-encoded mitochondrial proteins, which is necessary for life at the cellular level. Analysis of lymphoblastoid cells and fibroblasts from patients homozygous for the PMPCA p.Ala377Thr mutation and carriers demonstrate that the mutation impacts both the level of the alpha subunit encoded by PMPCA and the function of mitochondrial processing peptidase. In particular, this mutation impacts the maturation process of frataxin, the protein which is depleted in Friedreich ataxia. This study represents the first time that defects in PMPCA and mitochondrial processing peptidase have been described in association with a disease phenotype in humans. PMID:25808372