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1

Posterior fossa arachnoid cysts and cerebellar tonsillar descent: short review  

Microsoft Academic Search

The objective of this study was to analyze the association of cerebellar tonsillar descent and syringomyelia in patients with\\u000a posterior fossa arachnoid cysts. We reviewed the medical records of ten patients (mean, age 33; range, 24–49 years) diagnosed\\u000a with posterior fossa arachnoid cyst and tonsillar descent. Symptoms evolved over a mean of 12 months (range, 6 months to 3 years).\\u000a Syringomyelia was present in

Marcelo Galarza; Antonio López López-Guerrero; Juan F. Martínez-Lage

2010-01-01

2

Dimensions of the posterior fossa in patients symptomatic for Chiari I malformation but without cerebellar tonsillar descent  

PubMed Central

Background Chiari I malformation (CMI) is diagnosed by rigid radiographic criteria along with appropriate clinical symptomatology. The aim of this study was to investigate the dimensions of the posterior cranial fossa in patients without significant tonsillar descent but with symptoms comparable to CMI. Methods Twenty-two patients with signs and symptoms comparable to CMI but without accepted radiographic criteria of tonsillar descent > 3–5 mm were referred to our clinic for evaluation. A history and physical examination were performed on all patients. In reviewing their MRI scans, nine morphometric measurements were recorded. The measurements were compared to measurements from a cohort of twenty-five individuals with cranial neuralgias from our practice. Results For patients with Chiari-like symptomatology, the following statistically significant abnormalities were identified: reduced length of the clivus, reduced length of basisphenoid, reduced length of basiocciput, and increased angle of the tentorium. Multiple morphometric studies have demonstrated similar findings in CMI. Conclusion The current classification of CMI is likely too restrictive. Preliminary morphologic data suggests that a subgroup of patients exists with tonsillar descent less than 3 mm below the foramen magnum but with congenitally hypoplastic posterior fossa causing symptomatology consistent with CMI. PMID:16359556

Sekula, Raymond F; Jannetta, Peter J; Casey, Kenneth F; Marchan, Edward M; Sekula, L Kathleen; McCrady, Christine S

2005-01-01

3

Symptomatic tonsillar ectopia  

PubMed Central

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

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

1998-01-01

4

Flaccid quadriplegia from tonsillar herniation in pneumococcal meningitis  

Microsoft Academic Search

A young woman with fulminant pyogenic meningitis became quadriplegic, areflexic and flaccid due to herniation of the cerebellar tonsils and compression of the upper cervical cord. This state of spinal shock was associated with absent F-waves. Intracranial pressure was greatly elevated and there was an uncertain relationship of tonsillar descent to a preceding lumbar puncture. Partial recovery occurred over 2

A. H. Ropper; K. B. Kanis

2000-01-01

5

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

PubMed Central

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

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

6

Hypertrophy, Tonsillar (Enlarged Tonsils) (For Parents)  

MedlinePLUS

... Social Media: Connect With Us A to Z: Hypertrophy, Tonsillar (Enlarged Tonsils) KidsHealth > Parents > A to Z > ... to Know Keep in Mind A to Z: Hypertrophy, Tonsillar (Enlarged Tonsils) May also be called: Enlarged ...

7

Cerebellar Degeneration  

MedlinePLUS

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

8

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

PubMed Central

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

Rodriguez-Hernandez, Ana; Kim, Helen; Pourmohamad, Tony; Young, William L.; Lawton, Michael T.

2013-01-01

9

Cerebellar mutism.  

PubMed

Mutism of cerebellar origin is a well-described clinical entity that complicates operations for posterior fossa tumors, especially in children. This review focuses on the current understanding of principal pathophysiological aspects and risk factors, epidemiology, clinical characteristics, treatment strategies, and outcome considerations. The PubMed database was searched using the term cerebellar mutism and relevant definitions to identify publications in the English-language literature. Pertinent publications were selected from the reference lists of the previously identified articles. Over the last few years an increasing number of prospective studies and reviews have provided valuable information regarding the cerebellar mutism syndrome. Importantly, the clarification of principal terminology that surrounds the wide clinical spectrum of the syndrome results in more focused research and more effective identification of this entity. In children who undergo surgery for medulloblastoma the incidence of cerebellar mutism syndrome was reported to be 24%, and significant risk factors so far are brainstem involvement and midline location of the tumor. The dentate-thalamo-cortical tracts and lesions that affect their integrity are considered significant pathophysiological issues, especially the tract that originates in the right cerebellar hemisphere. Moderate and severe forms of the cerebellar mutism syndrome are the most frequent types during the initial presentation, and the overall neurocognitive outcome is not as favorable as thought in the earlier publications. Advanced neuroimaging techniques could contribute to identification of high-risk patients preoperatively and allow for more effective surgical planning that should focus on maximal tumor resection with minimal risk to important neural structures. Properly designed multicenter trials are needed to provide stronger evidence regarding effective prevention of cerebellar mutism and the best therapeutic approaches for such patients with a combination of pharmacological agents and multidisciplinary speech and behavior augmentation. PMID:24073751

Pitsika, Marina; Tsitouras, Vassilios

2013-12-01

10

Ultramicroscopic examination of the ovine tonsillar epithelia.  

PubMed

As solid morphological knowledge of ovine tonsillar epithelia might contribute to a better understanding of the pathogenesis of several diseases including prion diseases, the epithelia of all tonsils of 7 one-year-old Texel sheep were examined using scanning and transmission electron microscopy. Major parts of the pharyngeal and tubal tonsils were covered by pseudostratified columnar ciliated epithelia that were interrupted by patches of epithelium containing cells with densely packed microfolds or microvilli, and cells with both microvilli and cilia. Smaller parts were covered by either flattened polygonal cells with densely packed microvilli or microfolds, squamous epithelial cells, or patches of reticular epithelium. The palatine and paraepiglottic tonsils were mainly lined by squamous epithelial cells with apical microplicae or short knobs. Additionally, regions of reticular epithelium containing epithelial cells with apical microvilli were seen. The lingual tonsil was uniformly covered by a keratinized squamous epithelium and devoid of microvillous cells and patches of reticular epithelium. The rostral half of the tonsil of the soft palate was lined by a pseudostratified columnar ciliated epithelium with characteristics of the pharyngeal and tubal tonsils. The epithelium of the caudal part resembled the epithelia of the palatine and paraepiglottic tonsils. Putative M cells, mainly characterized by apical microvilli or microfolds and a close association with lymphoid cells, seem manifestly present on the nasopharyngeal tonsils. The reticular epithelium of the palatine and paraepiglottic tonsils also harbor cells with small apical microvilli. The exact nature of these presumptive M cells should, however, be elucidated in functional studies. PMID:20225209

Casteleyn, Christophe; Cornelissen, Maria; Simoens, Paul; Van den Broeck, Wim

2010-05-01

11

Cerebellar mutism.  

PubMed

Cerebellar mutism occurs in about 25% of children following posterior fossa tumor surgery. It is usually accompanied by other neurological and behavioral disturbances. Mutism is transient in nature lasting several days to months and is frequently followed by dysarthria. In addition, impairment of language and other neuropsychological functions can be found after long term follow up in the majority of patients. The pathophysiological background of mutism may be higher speech dysfunction mediated by crossed cerebello-cerebral diaschisis which is frequently found during the mute period. Foremost injury to the bilateral dentatothalamocortical tract appears to be critical for the development of cerebello-cerebral diaschisis and subsequent mutism. Direct cerebellar injury is the likely reason for persisting deficits after the mute period. Minimization of injury to the dentatothalamocortical tract during surgery may be promising in the prevention of mutism. While there is no established treatment of mutism, early speech and rehabilitation therapy is recommended. PMID:23398780

Küper, Michael; Timmann, Dagmar

2013-12-01

12

A study of greyhounds with tonsillar enlargement and a history of poor racing performance.  

PubMed

Fifteen greyhounds with tonsillar enlargement were subjected to detailed investigation. Affected greyhounds exhibited coughing, poor racing performance and tonsillar lymphoid hyperplasia over a period of months. Each of the 15 affected animals had evidence of respiratory tract disease. Twelve had non-specific respiratory tract disease, two had pneumonia and one had pulmonary infiltration with eosinophils (PIE). Histopathological examination of the tonsils from affected dogs revealed that greyhounds with tonsillar enlargement are more likely to have tonsillar lymphoid hyperplasia than tonsillitis. As a result, lymphoid hyperplasia would be a suitable term to describe this tonsillar condition. Respiratory tract diseases, rather than tonsillar hyperplasia, was the more likely cause of the poor racing performance of affected dogs. The aetiological relationship, if any, between respiratory disease and tonsillar enlargement is unclear from this study and requires further investigation. PMID:12359465

Montague, A L; Markey, B K; Bassett, H F; Jones, B R; Larkin, H; Mcallister, H; Quinn, P J

2002-09-01

13

Scar contracture of anterior tonsillar pillar leading to difficult intubation  

PubMed Central

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.

Kapoor, Hemlata; Mokashi, Suhas

2014-01-01

14

Ascent/Descent Software  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

15

Descent Into Darkness  

E-print Network

DESCENT INTO DARKNE BY JOAN MARIE VERBA. edited by Ruth Berman proofreading: Kay Brown cover calligraphy by Joan Marie Verba Copyright (c) 1988 by Joan Marie Verba. Only original material within is covered by this copyright. DESCENT..., and Scott is the captain of engineering. The ENTERPRISE has been refitted with a variant of the multitronic computer, called the multiplex, and a full automation system is in place. Captain Adele Smetana, a student of DayStrom's, installed the computer...

Vreba, Joan Marie

1988-01-01

16

Clinical manifestations and pathogenesis of tonsillar focal diseases: IgA nephropathy and palmoplantar pustulosis.  

PubMed

Tonsillar focal disease is defined as clinical disorders in the distant organ from the tonsil that are caused by the tonsils without any symptoms of the tonsil itself. Palmoplantar pustulosis and IgA nephropathy are known typical tonsillar focal diseases. In this paper, the clinical outcome of tonsillectomy and the etiological evidence of related diseases are reviewed. PMID:21865679

Harabuchi, Yasuaki

2011-01-01

17

Cerebellar calcification and lead  

Microsoft Academic Search

In elderly subjects who were brought up in a known high lead environment in Queensland, Australia, childhood residence and occupational status provide circumstantial evidence of a relationship between excessive lead intake and cerebellar calcification as seen on computed tomography. This supports experimental and neuropathological studies demonstrating an association between exposure to lead and perivascular cerebellar calcification.

M D Benson; J Price

1985-01-01

18

Asymptomatic tonsillar herniation in a neonate with cleidocranial dysplasia.  

PubMed

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

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

2014-02-01

19

HPV positive tonsillar cancer in two laser surgeons: case reports.  

PubMed

A 53 year-old male gynecologist presented with human papillomavirus (HPV) 16 positive tonsillar squamous cell carcinoma. He had no identifiable risk factors with the exception of long term occupational exposure to laser plumes, having performed laser ablations and loop electrosurgical excision procedures (LEEP) on greater than 3000 dysplastic cervical and vulvar lesions over 20 years of practice. The second patient is a 62 year old male gynecologist with a 30 year history of laser ablation and LEEP who subsequently developed HPV 16 positive base of tongue cancer. He also had very few other risk factors for oropharyngeal cancer or HPV infection. HPV is a probable causative agent for oropharyngeal squamous cell carcinoma and has been reported as being transmittable through laser plume. This paper suggests that HPV transmitted through laser plume can result in subsequent squamous cell carcinoma. PMID:24246045

Rioux, Margo; Garland, Andrea; Webster, Duncan; Reardon, Edward

2013-01-01

20

HPV positive tonsillar cancer in two laser surgeons: case reports  

PubMed Central

A 53 year-old male gynecologist presented with human papillomavirus (HPV) 16 positive tonsillar squamous cell carcinoma. He had no identifiable risk factors with the exception of long term occupational exposure to laser plumes, having performed laser ablations and loop electrosurgical excision procedures (LEEP) on greater than 3000 dysplastic cervical and vulvar lesions over 20 years of practice. The second patient is a 62 year old male gynecologist with a 30 year history of laser ablation and LEEP who subsequently developed HPV 16 positive base of tongue cancer. He also had very few other risk factors for oropharyngeal cancer or HPV infection. HPV is a probable causative agent for oropharyngeal squamous cell carcinoma and has been reported as being transmittable through laser plume. This paper suggests that HPV transmitted through laser plume can result in subsequent squamous cell carcinoma. PMID:24246045

2013-01-01

21

Terminal Descent Sensor Simulation  

NASA Technical Reports Server (NTRS)

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.

Chen, Curtis W.

2009-01-01

22

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

Microsoft Academic Search

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

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

23

Does cooling the tonsillar fossae during thermal welding tonsillectomy have an effect on postoperative pain and healing?  

PubMed

The objective of this study was to evaluate the effect of cooling the tonsillar fossa during thermal welding tonsillectomy on pain and wound healing. Prospective, blinded, clinical study was conducted. 30 patients who underwent tonsillectomy by thermal welding were evaluated. When one of the tonsillar fossa was cooled by isotonic fluid, the other has left untreated. Postoperative pain and mucosal healing pattern were assessed. Data were recorded and statistically analyzed. Healing process of the cooled down tonsillar fossae were significantly better on the 7th and 14th postoperative day (p < 0.01). Control tonsillar fossae had significantly higher pain scores on the 3rd, 7th and 14th postoperative day (p < 0.05). Administration of isotonic fluid, during thermal welding tonsillectomy for cooling tonsillar fossae, accelerates wound-healing process significantly and decreases tonsillectomy related pain complaints post-operatively. PMID:22843096

Tepe Karaca, Ci?dem; Celebi, Saban; Oysu, Ca?atay; Celik, Oner

2013-01-01

24

Descent and descent groups in lovedu social structure  

Microsoft Academic Search

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

Eileen Jensen Krige

1985-01-01

25

Metronidazole induced cerebellar ataxia  

PubMed Central

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

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

2013-01-01

26

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

E-print Network

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

Alfonseca, Manuel

27

Consert during the Philae Descent  

NASA Astrophysics Data System (ADS)

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.

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

28

Descent theory for semiorthogonal decompositions  

SciTech Connect

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.

Elagin, Alexei D

2012-05-31

29

Algorithm for Fuel-Conservative Airplane Descents  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

30

Efficacy of Penicillin versus Cefdinir in Eradication of Group A Streptococci and Tonsillar Flora  

Microsoft Academic Search

Core tonsillar cultures were obtained from 40 children with recurrent tonsillitis treated with either penicillin or cefdinir. Group A beta-hemolytic streptococci were isolated from 11 penicillin- and 3 cefdinir-treated (P < 0.001) patients. -Lactamase producers were recovered from 17 penicillin- and 3 cefdinir-treated (P < 0.01) patients. Inhibiting alpha-hemolytic streptococci were isolated less often from penicillin-treated patients than from cefdinir-treated

Itzhak Brook; Perry A. Foote

2005-01-01

31

Cerebellar pathology in tuberous sclerosis.  

PubMed

Cerebellar involvement in tuberous sclerosis is rare and generally nonsymptomatic. The authors describe a cerebellar tuber in a 5-year-old boy with tuberous sclerosis. A CT scan at age 2 years showed the characteristic cortical, white matter, and subependymal lesions of tuberous sclerosis. At 5 years, when the patient was symptomatic with ataxia, the CT and MRI scans revealed additionally the presence of a right cerebellar enhancing lesion with edema. A total surgical resection was undertaken. The cerebellar lesion was very firm and demonstrated marked disorganization of neuronal architecture in the cerebellar folia, with bizzare ectopic neurons in the molecular and granule cell layers and white matter, along with calcification, gliosis, and Rosenthal fiber deposition. Balloon cells with glassy, pale, eosinophilic cytoplasm were also present. There was a marked loss of myelin in the white matter, with significant vacuolation and gliosis. Electron microscopy documented abundant lysosomal inclusions, prominent rough endoplasmic reticulum and Golgi complexes, microtubules, intermediate filaments, and synaptic contacts. While there is much speculation as to the precise nature of cerebellar pathology in tuberous sclerosis, this case demonstrates conclusively that the cerebellar lesions reflect anomolous neuronal development and migration akin to supratentorial lesions and can rarely be symptomatic. PMID:9805358

Jay, V; Edwards, V; Musharbash, A; Rutka, J T

1998-01-01

32

Lymph drainage from the ovine tonsils: an anatomical study of the tonsillar lymph vessels.  

PubMed

Although the tonsils of sheep have gained much attention during the last decade, only few data are available on their lymph vessel architecture. Tonsillar lymph vessels are immunologically important as they form the efferent routes for locally activated immune cells to reach the draining lymph nodes. To gain insight into the tonsillar lymph drainage in the sheep, Indian ink and a casting polymer were injected into the interstitium of the five tonsils present in the heads of slaughtered sheep. This enabled us to determine the draining lymph node and to examine the microscopic organization of lymph vessels using light and scanning electron microscopy. No lymph vessels were observed within the tonsillar lymphoid follicles. The corrosion casts demonstrated that the lymphoid follicles are surrounded by numerous sacculated lymph sinuses that drain into a dense interfollicular lymph vessel network. From here, the lymph flows into single small lymph vessels that in turn drain into larger lymph vessels extending towards the medial retropharyngeal lymph node. The presented results can be valuable for immunological studies, for example during oral or intranasal vaccine development. PMID:24597835

Casteleyn, C; Cornillie, P; Van Ginneken, C; Simoens, P; Van Cruchten, S; Vandevelde, K; Van den Broeck, W

2014-12-01

33

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

NASA Technical Reports Server (NTRS)

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.

Stell, Laurel L.

2010-01-01

34

The mysterious microcircuitry of the cerebellar nuclei  

PubMed Central

Abstract The microcircuitry of cerebellar cortex and, in particular, the physiology of its main element, the Purkinje neuron, has been extensively investigated and described. However, activity in Purkinje neurons, either as single cells or populations, does not directly mediate the cerebellar effects on the motor effector systems. Rather, the result of the entire cerebellar cortical computation is passed to the relatively small cerebellar nuclei that act as the final, integrative processing unit in the cerebellar circuitry. The nuclei ultimately control the temporal and spatial features of the cerebellar output. Given this key role, it is striking that the internal organization and the connectivity with afferent and efferent pathways in the cerebellar nuclei are rather poorly known. In the present review, we discuss some of the many critical shortcomings in the understanding of cerebellar nuclei microcircuitry: the extent of convergence and divergence of the cerebellar cortical pathway to the various cerebellar nuclei neurons and subareas, the possible (lack of) conservation of the finely-divided topographical organization in the cerebellar cortex at the level of the nuclei, as well as the absence of knowledge of the synaptic circuitry within the cerebellar nuclei. All these issues are important for predicting the pattern-extraction and encoding capabilities of the cerebellar nuclei and, until resolved, theories and models of cerebellar motor control and learning may err considerably. PMID:21521761

Uusisaari, Marylka; De Schutter, Erik

2011-01-01

35

Tonsillar ectopia in idiopathic scoliosis: does it play a role in the pathogenesis and prognosis or is it only an incidental finding?  

Microsoft Academic Search

BACKGROUND: There is an ongoing controversy about the significance of tonsillar ectopia among patients with idiopathic scoliosis (IS). AIM: To find out if tonsillar ectopia occurs more frequently among patients with IS and if it plays any etiological or prognostic role in IS. STUDY DESIGN: Retrospective study. METHODS: Retrospective analysis of 155 consecutive spine MRIs (79 patients with IS and

Kasim Abul-Kasim; Angelica Overgaard; Magnus K Karlsson; Acke Ohlin

2009-01-01

36

Molecular Mapping to Species Level of the Tonsillar Crypt Microbiota Associated with Health and Recurrent Tonsillitis  

PubMed Central

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

Jensen, Anders; Fago-Olsen, Helena; S?rensen, Christian Hjort; Kilian, Mogens

2013-01-01

37

Palatine tonsillar metastasis of rectal adenocarcinoma: a case report and literature review  

PubMed Central

Cases of primary colorectal adenocarcinoma metastasized to the palatine tonsil are extremely rare. To the best of our knowledge, only 10 cases have thus far been previously documented in the English literature. A 37-year-old Chinese woman presented with a right palatine tonsil swelling and odynophagia 5 months after a surgical resection of rectal adenocarcinoma was performed. The patient underwent a tonsillectomy, and a metastatic poorly differentiated adenocarcinoma from a colorectal origin was revealed by immunohistochemical analysis. The manner in which tonsillar metastases are involved remains unknown and should be further studied. Here, we report a new case, briefly summarize these 10 cases and review the literature. PMID:23705669

2013-01-01

38

Genetics Home Reference: Lissencephaly with cerebellar hypoplasia  

MedlinePLUS

... cerebellar hypoplasia? Lissencephaly with cerebellar hypoplasia (LCH) affects brain development, resulting in the brain having a smooth appearance ( ... structures do not develop properly. This impairment of brain development leads to the neurological problems characteristic of LCH. ...

39

Feature Clustering for Accelerating Parallel Coordinate Descent  

SciTech Connect

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.

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

2012-12-06

40

Lunar descent using sequential engine shutdown  

E-print Network

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 ...

Springmann, Philip N

2006-01-01

41

Descent relations in cubic superstring field theory  

NASA Astrophysics Data System (ADS)

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.

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

2008-01-01

42

Human factors by descent energy management  

NASA Technical Reports Server (NTRS)

This paper describes some of the results of a human factors study of energy management during descent using standard aircraft displays. Discussions with pilots highlighted the practical constraints involved and the techniques (algorithms) used to accomplish the descent. The advantages and disadvantages of these algorithms are examined with respect to workload and their sensitivity to disturbances. Vertical navigation and flight performance computers are discussed in terms of the information needed for effective pilot monitoring and takeover

Curry, R. E.

1979-01-01

43

Typical features of cerebellar ataxic gait  

Microsoft Academic Search

Background: Although gait disturbance is one of the most pronounced and disabling symptoms in cerebellar disease (CD), quantitative studies on this topic are rare.Objectives: To characterise the typical clinical features of cerebellar gait and to analyse ataxia quantitatively.Methods: Twelve patients with various cerebellar disorders were compared with 12 age matched controls. Gait was analysed on a motor driven treadmill using

H Stolze; S Klebe; G Petersen; J Raethjen; R Wenzelburger; K Witt; G Deuschl

2002-01-01

44

Cerebellar Function, Dyslexia and Articulation Speed  

Microsoft Academic Search

The main aims of this study were a) to assess the cerebellar deficit hypothesis examining children's performance in cerebellar and cognitive tasks associated with the dyslexic syndrome and b) to investigate if there is a differentiation in articulation speed in children with dyslexia. A battery consisted of five cerebellar tests, five cognitive tests, and an articulation speed test was administered

D. S. Kasselimis; M. Margarity; F. Vlachos

2008-01-01

45

A theory of cerebellar function  

Microsoft Academic Search

A comprehensive theory of cerebellar function is presented, which ties together the known anatomy and physiology of the cerebellum into a pattern -recognition data processing system. The cerebellum is postulated to be functionally and structurally equivalent to a modification of the classical Perceptron pattern -classification device. It is suggested that the mossy fiber -+ granule cell -+ Golgicell input network

JAMES S. ALBUS

1971-01-01

46

Brain death due to fat embolism -- could moderate hypercapnia and prone position be blamed for the tonsillar herniation?  

PubMed Central

Fat embolism to the systemic circulation in polytrauma patients is very common. The fat embolism syndrome (FES), however, is a rare condition. We describe a case of traumatic femur fracture with FES that was presented as acute tonsillar herniation (coning) and brain death postoperatively. We believe that in this case the prone position and moderate hypercapnia contributed to the acute coning. PMID:23977867

Larsson, Anders

2013-01-01

47

Surgical treatment of cerebellar metastases  

PubMed Central

Background: Cerebral metastases are a common neurosurgical finding. Surgery confers several advantages to other therapies, including immediate symptomatic improvement, diagnosis, and relief from corticosteroid dependence. Here we evaluate patients with cerebellar metastases who underwent surgery and compare their findings to those in the literature, and address the benefit of avoiding ventriculo-peritoneal shunting in patients undergoing surgery. Methods: We performed a retrospective analysis involving 50 patients with cerebellar metastases who underwent surgical resection. Ventriculo-peritoneal shunts were placed in patients necessitating permanent CSF drainage. We evaluated presentation, diagnosis, complications, and outcome. Results: Our review included 21 males and 29 females, 29 to 82 years of age. Primary tumors included lung (48%), breast (14%), GI (14%), endometrial/ovarian (6%), melanoma (6%), sarcoma (4%), lymphoma (4%), laryngeal (2%), and other (2%). Clinical symptoms at presentation commonly were those secondary to elevated intracranial pressure and were the initial complaint in 34% of patients. Preoperatively, 29 patients were noted to have hydrocephalus. Importantly, 76% of these patients were able to avoid placement of a ventriculo-peritoneal shunt following surgery. Only two complications were noted in our series of 50 patients, including a symptomatic pseudomeningocele and a wound infection. No symptomatic postoperative hematoma developed in any surgical case. Conclusion: A review of the literature has shown a high complication rate in patients undergoing surgical resection of cerebellar metastases. We have shown that surgical resection of cerebellar metastases is a safe procedure and is effective in the treatment of hydrocephalus in the majority of patients harboring cerebellar lesions. PMID:22140644

Ghods, Ali J.; Munoz, Lorenzo; Byrne, Richard

2011-01-01

48

Mars Science Laboratory Rover and Descent Stage  

NASA Technical Reports Server (NTRS)

In this February 17, 2009, image, NASA's Mars Science Laboratory rover is attached to the spacecraft's descent stage. The image was taken inside the Spacecraft Assembly Facility at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

This is the way the spacecraft will look after it comes out of its protective aeroshell and is descending to the Martian surface in 2012. Here, the descent stage sits on top of the rover, with its eight main engines straddling the rover structure. The rover is the big white box below the descent stage. At this point, the rover lacks its appendages (robotic arm, mast and most wheels), as these elements are still being assembled and were not needed for space-simulation testing of the spacecraft in late 2008.

2009-01-01

49

Entry, Descent, and Landing With Propulsive Deceleration  

NASA Technical Reports Server (NTRS)

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

Palaszewski, Bryan

2012-01-01

50

Expression and function of IL-12 and IL-18 receptors on human tonsillar B cells.  

PubMed

IL-12 activates murine and human B cells, but little information is available as to the expression and function of IL-12R on human B lymphocytes. Here we show that the latter cells, freshly isolated from human tonsils, expressed the transcripts of both beta1 and beta2 chains of IL-12R and that beta2 chain mRNA was selectively increased (4- to 5-fold) by incubation with Staphylococcus aureus Cowan I bacteria or IL-12. B cell stimulation with IL-12 induced de novo expression of the transcripts of the two chains of IL-18R, i.e., IL-1 receptor-related protein and accessory protein-like. Functional studies showed that both IL-12 and IL-18 signaled to B cells through the NF-kappaB pathway. In the case of IL-12, no involvement of STAT transcription factors, and in particular of STAT-4, was detected. c-rel and p50 were identified as the members of NF-kappaB family involved in IL-12-mediated signal transduction to B cells. IL-12 and IL-18 synergized in the induction of IFN-gamma production by tonsillar B cells, but not in the stimulation of B cell differentiation, although either cytokine promoted IgM secretion in culture supernatants. Finally, naive but not germinal center or memory, tonsillar B cells were identified as the exclusive IL-12 targets in terms of induction of NF-kappaB activation and of IFN-gamma production. PMID:11120812

Airoldi, I; Gri, G; Marshall, J D; Corcione, A; Facchetti, P; Guglielmino, R; Trinchieri, G; Pistoia, V

2000-12-15

51

Cerebellar arteriovenous malformations in children  

Microsoft Academic Search

We review the presentation, imaging findings and outcome in 18 children with cerebellar arteriovenous malformations (AVM).\\u000a This group is of particular interest because of the reported poor outcome despite modern imaging and neurosurgical techniques.\\u000a All children had CT and 15 underwent catheter angiography at presentation. Several of the children in the latter part of the\\u000a study had MRI. Of the

P. D. Griffiths; S. Blaser; D. Armstrong; S. Chuang; R. P. Humphreys; D. Harwood-Nash

1998-01-01

52

Cerebellar agenesis and diabetes insipidus.  

PubMed

We report on a 7-year-old female, born after a normal pregnancy at term, previously referred because of delayed psychomotor development. MRI revealed isolated cerebellar agenesis (CA) with only minute tissue remnants of the anterior vermis/paravermian anterior quadrangular lobes and pontine hypoplasia. The patient demonstrated truncal ataxia, saccadic ocular pursuit and mild gaze evoked nystagmus. At the age of 2.5 years, the girl achieved independent walking, though with a markedly ataxic gait; at the same age diabetes insipidus was recognized and appropriately treated. This association has not been reported before. At the ages of 3.5 and 6.5 years, her developmental quotient (DQ) was 65 and 60, respectively, with a very poor vocabulary and cerebellar dysarthria. The term "agenesis" is problematic as several reports describe considerable cerebellar tissue remnants and may include pontocerebellar hypoplasia. A literature review disclosed only a few patients with CA (defined in a strict sense) diagnosed in vivo by MRI. It is questionable whether asymptomatic CA occurs. PMID:15627945

Zafeiriou, D I; Vargiami, E; Boltshauser, E

2004-12-01

53

a perry descent conjugate gradient method with restricted spectrum ...  

E-print Network

liminary numerical results for a set of 720 unconstrained optimization ... Key words and phrases. large scale optimization, conjugate gradient method, descent property ...... and H. Zhang for CG DESCENT code and J. J. Moré for Matlab code

2011-05-09

54

Recursive descent parsing for Boolean grammars  

Microsoft Academic Search

The recursive descent parsing method for the context-free grammars is extended for their generalization, Boolean grammars, which include explicit set-theoretic operations in the formalism of rules and which are formally defined by language equations. The algorithm is applicable to a subset of Boolean grammars. The complexity of a direct implementation varies between linear and exponential, while memoization keeps it down

Alexander Okhotin

2007-01-01

55

Research study: STS-1 Orbiter Descent  

NASA Technical Reports Server (NTRS)

The conversion of STS-1 orbiter descent data from AVE-SESAME contact programs to the REEDA system and the reduction of raw radiosonde data is summarized. A first difference program, contact data program, plot data program, and 30 second data program were developed. Six radiosonde soundings were taken. An example of the outputs of each of the programs is presented.

Hickey, J. S.

1981-01-01

56

[Cerebellar infarction: analysis of 151 patients].  

PubMed

This report presents the treatment of 151 patients with cerebellar infarction, 98 men (65%) and 53 women (35%), mean age 62.4 years old. Occlusive hydrocephalus was diagnosed in 7.9% of the patients associated with an extensive cerebellar infarction and in all 11 surgical patients (7.2%). Four patients underwent an external ventricular drainage with 3 deaths (75%) and 7 underwent a decompressive suboccipital craniectomy with 2 deaths (28.5%). Mortality of the clinical group was 15 patients (10.7%). Vertigo, vomiting, Romberg sign and dysmetria were the signs and symptoms of cerebellar involvement that were most frequently observed. Cerebellar infarction from embolism after cardiovascular surgery occurred in 57 patients (37.7%). Cerebellar infarction, as an isolated fact, occurred in 59 patients (39%) and cerebellar plus infarction in other regions occurred in 92 patients (61%). Magnetic resonance image was the best diagnostic form for cerebellar lesions, however computerized tomography could show cerebellar infarction in 68 patients (78%). PMID:16917619

Rosi, Jefferson; de Oliveira, Paulo Geraldo Dorsa; Montanaro, Antônio Carlos; Gomes, Sidney; Godoy, Roberto

2006-06-01

57

Cerebellar Stroke-manifesting as Mania  

PubMed Central

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

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

2014-01-01

58

Flat descent for Artin n-stacks  

Microsoft Academic Search

We prove two flat descent statements for Artin n-stacks. We first show that an n-stack for the etale topology which is an Artin n-stack in the sense of HAGII, is also an n-stack for the fppf topology. Moreover, an n-stack for the fppf topology which possess a fppf n-atlas is an Artin n-stack (i.e. possesses a smooth n-atlas). We deduce

Bertrand Toen; Case Courrier; Eugene Bataillon

2009-01-01

59

Stochastic Gradient Descent Tricks Leon Bottou  

E-print Network

answer is y, and we choose a family F of functions fw(x) parametrized by a weight vector w. We seek the function f F that minimizes the loss Q(z, w) = (fw(x), y) averaged on the examples. Although we would like the empirical risk En(fw) using gradient descent (GD). Each iteration updates the weights w on the basis

Bottou, Léon

60

On Early Stopping in Gradient Descent Learning  

Microsoft Academic Search

In this paper we study a family of gradient descent algorithms to approximate the regression function from reproducing kernel\\u000a Hilbert spaces (RKHSs), the family being characterized by a polynomial decreasing rate of step sizes (or learning rate). By\\u000a solving a bias-variance trade-off we obtain an early stopping rule and some\\u000a probabilistic upper bounds for the convergence of the algorithms. We

Yuan Yao; Lorenzo Rosasco; Andrea Caponnetto

2007-01-01

61

Frequency and Clinical Significance of Acute Bilateral Cerebellar Infarcts  

Microsoft Academic Search

Background: Unlike acute unilateral cerebellar infarct (UCI), acute bilateral cerebellar infarcts (BCI) have attracted little attention. To evaluate the clinical significance of BCI, we compared UCI and BCI and analyzed potentially prognostic factors. Methods: Patients who were consecutively admitted at a university hospital over a 4-year period with acute cerebellar infarcts, proven by diffusion-weighted imaging, were studied. Cerebellar infarcts were

Ji Man Hong; Oh Young Bang; Chin-Sang Chung; In Soo Joo; Kyoon Huh

2008-01-01

62

Time Estimation Deficits in Developmental Dyslexia: Evidence of Cerebellar Involvement  

Microsoft Academic Search

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

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

1995-01-01

63

Heterozygous Alterations of TNFRSF13B/TACI in Tonsillar Hypertrophy and Sarcoidosis  

PubMed Central

TNFRSF13B/TACI defects have been associated with CVID pathogenesis and/or phenotype, especially the development of benign lymphoproliferation and autoimmunity. Our purpose was to investigate the role of TNFRSF13B/TACI defects in the pathogenesis of two common lymphoproliferative disorders, namely, sarcoidosis and tonsillar hypertrophy (TH). 105 patients (71 with sarcoidosis and 34 with TH, including 19 without infectious causative and 15 due to Haemophilus influenzae) were analyzed for TNFRSF13B/TACI defects. Two out of 19 TH patients without infectious cause (10.5%) and 2 patients with sarcoidosis (2.8%) displayed rare TNFRSF13B/TACI defects (I87N, L69TfsX12, E36L, and R202H, resp.). Both mutations identified in TH patients have been assessed as deleterious for protein function, while the patient with the R202H mutation and sarcoidosis exhibited also sIgG4D. Our study further supports the notion that TNFRSF13B/TACI defects alone do not result in CVID but may be also found frequently in distinct clinical phenotypes, including benign lymphoproliferation and IgG subclass deficiencies. PMID:23956760

Florou, Zoe; Petinaki, Efthimia; Daniil, Zoe; Bardaka, Fotini; Gourgoulianis, Konstantinos I.; Skoulakis, Charalampos; Germenis, Anastasios E.

2013-01-01

64

Cerebellar motor function in spina bifida meningomyelocele.  

PubMed

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

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

2010-12-01

65

X-linked disorders with cerebellar dysgenesis  

PubMed Central

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

2011-01-01

66

Origin, lineage and function of cerebellar glia.  

PubMed

The glial cells of the cerebellum, and particularly astrocytes and oligodendrocytes, are characterized by a remarkable phenotypic variety, in which highly peculiar morphological features are associated with specific functional features, unique among the glial cells of the entire CNS. Here, we provide a critical report about the present knowledge of the development of cerebellar glia, including lineage relationships between cerebellar neurons, astrocytes and oligodendrocytes, the origins and the genesis of the repertoire of glial types, and the processes underlying their acquisition of mature morphological and functional traits. In parallel, we describe and discuss some fundamental roles played by specific categories of glial cells during cerebellar development. In particular, we propose that Bergmann glia exerts a crucial scaffolding activity that, together with the organizing function of Purkinje cells, is necessary to achieve the normal pattern of foliation and layering of the cerebellar cortex. Moreover, we discuss some of the functional tasks of cerebellar astrocytes and oligodendrocytes that are distinctive of cerebellar glia throughout the CNS. Notably, we report about the regulation of synaptic signalling in the molecular and granular layer mediated by Bergmann glia and parenchymal astrocytes, and the functional interaction between oligodendrocyte precursor cells and neurons. On the whole, this review provides an extensive overview of the available literature and some novel insights about the origin and differentiation of the variety of cerebellar glial cells and their function in the developing and mature cerebellum. PMID:23981535

Buffo, Annalisa; Rossi, Ferdinando

2013-10-01

67

Cerebellar Motor Function in Spina Bifida Meningomyelocele  

PubMed Central

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

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

2010-01-01

68

Clinical characteristics and pathogenesis of cerebellar glioblastoma.  

PubMed

Cerebellar glioblastomas (GBMs) are rare, with neither their pathogenesis nor prognosis being completely understood. The present study aimed to clarify the clinical characteristics of cerebellar GBMs by comparison with supratentorial GBMs, focusing particularly on the pathogenesis. The clinical factors between cerebellar (n=10) and supratentorial (n=216) GBMs were compared. Additionally, p53 and epidermal growth factor receptor (EGFR) levels were investigated in six patients by immunostaining as well as the isocitrate dehydrogenase 1 (IDH1) status of five patients by direct sequencing. Eight males and two females participated in the present study, the mean age at diagnosis was 56.6 years and the range 37-75 years. Four patients presented with hydrocephalus and one with brainstem involvement, and two patients were diagnosed with neurofibromatosis type 1. Two patients had previously received radiotherapy, eight patients received postoperative radiotherapy and seven chemotherapy. The mean Karnofsky performance status (KPS) score was lower in patients with cerebellar GBMs compared to those with supratentorial GBM; however, the survival times did not differ between the two groups. All of the cases of six cerebellar GBMs were p53?positive and EGFR?negative, as detected by immunostaining, consistent with secondary GBM. However, no IDH1 mutations were detected in any of the five cases of cerebellar GBMs analyzed, indicating that these tumors were not of the secondary type. The KPS score with cerebellar GBMs may be lower due to hydrocephalus, which was ameliorated by surgery but may have impacted the survival rate. It was confirmed that cerebellar GBMs were identical to supratentorial GBMs with respect to its clinical features, with the possible exception of the KPS score. The present study's genetic analyses indicated that cerebellar GBMs may develop via a pathway different from that of either primary or secondary GBM. PMID:25199771

Takahashi, Yoshinobu; Makino, Keishi; Nakamura, Hideo; Hide, Takuichiro; Yano, Shigetoshi; Kamada, Hajime; Kuratsu, Jun-Ichi

2014-11-01

69

Cerebellar involvement in metabolic disorders: a pattern-recognition approach  

Microsoft Academic Search

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

M. Steinlin; S. Blaser; E. Boltshauser

1998-01-01

70

System for Estimating Horizontal Velocity During Descent  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

71

Unusual cerebellar ganglioglioma with marked cytologic atypia.  

PubMed

Neuronal differentiation is well documented in cerebellar primitive neuroectodermal tumors but is uncommon in other cerebellar neoplasms. Although rare, gangliogliomas and gangliocytomas have been previously described in the cerebellum. We report a cerebellar ganglioglioma in a 14-year-old boy, which revealed bizzare markedly pleomorphic cells with extremely pronounced nuclear atypia but less than one mitosis per 50 high-power fields and no necrosis. The tumor showed glial as well as neuronal differentiation, with abundant bi- and multinucleated ganglion cells. There were abundant Rosenthal fibers, eosinophilic granular bodies, focal calcification, and perivascular lymphocytic infiltrates. There has been no evidence of tumor recurrence or neurological deterioration 21 years after surgery, although the marked nuclear atypia led to an initial diagnosis of an anaplastic glioma. We stress the need for careful evaluation of cerebellar gliomas in children that show only nuclear atypia or endothelial hyperplasia in the absence of other features of malignancy. PMID:9050064

Jay, V; Greenberg, M

1997-01-01

72

Cognition and Emotion in Cerebellar Disorders  

MedlinePLUS

... uncommon in cerebellar disease, but can be a problem in those ataxic disorders that affect widespread areas of the cerebral cortex. The role of the cerebellum in dyslexia, attention deficit hyperactivity disorder, autism spectrum disorders, schizophrenia, ...

73

Cerebellar control of the inferior olive  

Microsoft Academic Search

A subpopulation of neurones in the cerebellar nuclei projects to the inferior olive, the source of the climbing fibre input\\u000a to the cerebellum. This nucleo-olivary projection follows the zonal and, probably also, the microzonal arrangement of the\\u000a cerebellum so that closed loops are formed between the neurones in the olive, the cerebellar cortex and the nuclei. The nucleo-olivary\\u000a pathway is

Fredrik Bengtsson; Germund Hesslow

2006-01-01

74

Hemorrhagic Transformation in Acute Cerebellar Infarction  

Microsoft Academic Search

Background: Hemorrhagic transformation (HT) is a well-known consequence of acute ischemic stroke, but little is known about HT in cerebellar infarction. Methods: Patients with acute cerebellar infarction within 48 h of onset were retrospectively recruited. MRI, including diffusion-weighted imaging (DWI) and T2*-gradient echo imaging (T2*), was performed twice (upon admission and 2 weeks after stroke onset). Infarct diameter and volume

Yuki Sakamoto; Kazumi Kimura; Yasuyuki Iguchi; Kensaku Shibazaki; Junya Aoki

2011-01-01

75

Cerebellar involvement of Griscelli syndrome type 2.  

PubMed

Griscelli syndrome type 2 is characterised by partial albinism and primary immunodeficiency. We present a case of a 3-year-old girl diagnosed with cerebellar involvement of Griscelli syndrome type 2. Neurological complications may accompany Griscelli syndrome, however, to the best of my knowledge there are only a few case reports of cerebellar involvement of Griscelli syndrome type 2 in the literature. PMID:25315806

I?ikay, Sedat

2014-01-01

76

Eyeblink conditioning indicates cerebellar abnormality in dyslexia  

Microsoft Academic Search

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

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

2002-01-01

77

African Descent and Glaucoma Evaluation Study (ADAGES)  

PubMed Central

Objective To define differences in optic disc, retinal nerve fiber layer, and macular structure between healthy participants of African (AD) and European descent (ED) using quantitative imaging techniques in the African Descent and Glaucoma Evaluation Study (ADAGES). Methods Reliable images were obtained using stereoscopic photography, confocal scanning laser ophthalmoscopy (Heidelberg retina tomography [HRT]), and optical coherence tomography (OCT) for 648 healthy subjects in ADAGES. Findings were compared and adjusted for age, optic disc area, and reference plane height where appropriate. Results The AD participants had significantly greater optic disc area on HRT (2.06 mm2; P<.001) and OCT (2.47 mm2; P<.001) and a deeper HRT cup depth than the ED group (P<.001). Retinal nerve fiber layer thickness was greater in the AD group except within the temporal region, where it was significantly thinner. Central macular thickness and volume were less in the AD group. Conclusions Most of the variations in optic nerve morphologic characteristics between the AD and ED groups are due to differences in disc area. However, differences remain in HRT cup depth, OCT macular thickness and volume, and OCT retinal nerve fiber layer thickness independent of these variables. These differences should be considered in the determination of disease status. PMID:20457974

Girkin, Christopher A.; Sample, Pamela A.; Liebmann, Jeffrey M.; Jain, Sonia; Bowd, Christopher; Becerra, Lida M.; Medeiros, Felipe A.; Racette, Lyne; Dirkes, Keri A.; Weinreb, Robert N.; Zangwill, Linda M.

2010-01-01

78

Krylov Subspace Descent for Deep Learning  

E-print Network

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 ...

Vinyals, Oriol

2011-01-01

79

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

Microsoft Academic Search

It has been suggested that interconnected brain areas evolve in tandem because evolutionary pressures act on complete functional systems rather than on individual brain areas. The cerebellar cortex has reciprocal connections with both the prefrontal cortex and motor cortex, forming independent loops with each. Specifically, in capuchin monkeys cerebellar cortical lobules Crus I and Crus II connect with prefrontal cortex,

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

2010-01-01

80

Teleconnection Mechanisms for Tropical Pacific Descent Anomalies during El Nino  

Microsoft Academic Search

Teleconnection mechanisms in relative descent zones are examined using the quasi-equilibrium tropical cir- culation model (QTCM). The regions of anomalous descent neighboring the warm sea surface temperature (SST) anomalies in the eastern and central Pacific Ocean during the 1997\\/98 El Nino are used as an example, and results are verified for three other El Nino warm events (1982, 1987, and

HUI S UA; NDJ. DAVID NEELIN

2002-01-01

81

RECURSIVE ASCENT-DESCENT PARSING R. Nigel Horspool  

E-print Network

RECURSIVE ASCENT-DESCENT PARSING R. Nigel Horspool Department of Computer Science, University-corner parsing was originally presented as a technique for generating a parser for the SLR1 class of grammars that subsumes the parsing methods known as recursive descent and recursive ascent hence the name recursive

Horspool, R. Nigel

82

Acculturation and Planning for College among Youth of Mexican Descent  

Microsoft Academic Search

This research examined associations between acculturation, college planning, and college attendance in 410junior and senior high school students. Participants, of which three quarters were of Mexican descent and one quarter was of European descent, completed Cuellar; Harris, and Jasso's acculturation scale and a college-planning survey. Ten months later; 116 of the 148 participating seniors were interviewed to determine if they

Maria T. Hurtado; Mary Gauvain

1997-01-01

83

Expression of CC chemokine receptor 7 in tonsillar cancer predicts cervical nodal metastasis, systemic relapse and survival  

PubMed Central

The aim of this study was to evaluate the expression of CC chemokine receptor 7 (CCR7) in squamous cell cancer of the tonsil with respect to patterns of spread, relapse-free, overall and disease-specific survival. Eighty-four patients with squamous cell cancer of the tonsil were identified. There was a male predominance of 3?:?1 and the median age at diagnosis was 53 (range 35–86) years. The median duration of follow-up was 33 (range 2–124) months. There was a significant association between CCR7 immunopositivity and synchronous cervical nodal metastasis in patients with tonsillar cancer (Spearman's correlation coefficient 0.564; P<0.001). Relapse-free (P=0.0175), overall (P=0.0136) and disease-specific (P=0.0062) survival rates were significantly lower in patients whose tumours expressed high levels of CCR7. On multivariate analysis, high-level CCR7 staining predicted relapse-free (hazard ratio 3.0, 95% confidence intervals 1.1–8.0, P=0.026) and disease-specific (hazard ratio 10.2, 95% confidence intervals 2.1–48.6, P=0.004) survival. Fifteen percent of patients with the highest level of tumour CCR7 immunopositivity relapsed with systemic metastases. These data demonstrated that CCR7 expression was associated with cervical nodal and systemic metastases from tonsillar cancers. High levels of CCR7 expression predicted a poor prognosis. PMID:17687340

Pitkin, L; Luangdilok, S; Corbishley, C; Wilson, P O G; Dalton, P; Bray, D; Mady, S; Williamson, P; Odutoye, T; Rhys Evans, P; Syrigos, K N; Nutting, C M; Barbachano, Y; Eccles, S; Harrington, K J

2007-01-01

84

Vision Based Approach for Entry Descent Landing  

NASA Astrophysics Data System (ADS)

The state of art of the Entry Descent Landing Vision Based algorithms is summarized in this article. A common request for the future scientific missions is the exploitation of a precise landing approach and the EDL Vision based technique is a key method to reach this goal. The three general typologies of EDL Vision Based approach are described. On the basis of these techniques Thales Alenia Space Italy has developed an EDL Vision Based architecture. A detailed description of the architecture is given and, for each main task introduced, the selected algorithm, or the ones under evaluation are described and the obtained preliminary results are shown. A last paragraph briefly describes the EDL laboratory in Thales Alenia Space Turin premises.

Lanza, P.; Cometto, F.; Martelli, A.

2009-05-01

85

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.

86

Distributed Control by Lagrangian Steepest Descent  

NASA Technical Reports Server (NTRS)

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.

Wolpert, David H.; Bieniawski, Stefan

2004-01-01

87

Planetary entry, descent, and landing technologies  

NASA Astrophysics Data System (ADS)

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.

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

2003-04-01

88

Metabolic anatomy of paraneoplastic cerebellar degeneration  

SciTech Connect

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

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

1988-06-01

89

Cerebellar modules operate at different frequencies  

PubMed Central

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

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

2014-01-01

90

21 CFR 882.5820 - Implanted cerebellar stimulator.  

Code of Federal Regulations, 2010 CFR

...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...

2010-04-01

91

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 ...

92

21 CFR 882.5820 - Implanted cerebellar stimulator.  

Code of Federal Regulations, 2012 CFR

...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...

2012-04-01

93

21 CFR 882.5820 - Implanted cerebellar stimulator.  

...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...

2014-04-01

94

Cerebellar contribution to feedforward control of locomotion  

PubMed Central

The cerebellum is an important contributor to feedforward control mechanisms of the central nervous system, and sequencing—the process that allows spatial and temporal relationships between events to be recognized—has been implicated as the fundamental cerebellar mode of operation. By adopting such a mode and because cerebellar activity patterns are sensitive to a variety of sensorimotor-related tasks, the cerebellum is believed to support motor and cognitive functions that are encoded in the frontal and parietal lobes of the cerebral cortex. In this model, the cerebellum is hypothesized to make predictions about the consequences of a motor or cognitive command that originates from the cortex to prepare the entire system to cope with ongoing changes. In this framework, cerebellar predictive mechanisms for locomotion are addressed, focusing on sensorial and motoric sequencing. The hypothesis that sequence recognition is the mechanism by which the cerebellum functions in gait control is presented and discussed. PMID:25009490

Pisotta, Iolanda; Molinari, Marco

2014-01-01

95

The anatomical substrate of cerebellar mutism.  

PubMed

Up to 39% of children operated for a posterior fossa tumor develop the cerebellar mutism syndrome. Although they are alert and cooperative, with normal language comprehension, they are unable to speak. In addition, patients may demonstrate apathy, bladder and bowel incontinence and long-term language and cognitive disturbances. This devastating syndrome is at the same time intriguing, because it confirms a role for the cerebellum in language and cognitive functions. Recent investigations have led to new insights regarding the cerebellar mutism syndrome. The commonly accepted hypothesis states that the mutism is caused by a hypofunction of cerebral hemispheres, due to damage to the superior cerebellar peduncle and functional disruption of the cerebello-cerebral circuitry. This article focuses on the evidence for and against this hypothesis and its clinical consequences. PMID:24735842

van Baarsen, Kirsten Margaretha; Grotenhuis, Joachim André

2014-06-01

96

CASE REPORT Open Access Autosomal recessive cerebellar ataxia caused  

E-print Network

CASE REPORT Open Access Autosomal recessive cerebellar ataxia caused by mutations in the PEX2 gene Objective: To expand the spectrum of genetic causes of autosomal recessive cerebellar ataxia (ARCA). Case is warranted in children and adults with ARCA. Background Main causes of autosomal recessive cerebellar ataxia

Paris-Sud XI, Université de

97

Cerebellar autoregulation dynamics in humans Matthias Reinhard1  

E-print Network

Cerebellar autoregulation dynamics in humans Matthias Reinhard1 , Zora Waldkircher1 , Jens Timmer2 Knowledge on autoregulation of cerebellar blood flow in humans is scarce. This study investigated whether cerebellar autoregulation dynamics and CO2 reactivity differ from those of the supratentorial circulation

Timmer, Jens

98

Cerebellar hypoperfusion in infantile neuroaxonal dystrophy.  

PubMed

An identical abnormal pattern was detected by means of (99m)Tc-hexamethyl-propyleneamine-oxime single-photon emission computed tomography in two siblings with infantile neuroaxonal dystrophy. The markedly decreased cerebellar perfusion, along with the early motor symptoms, characteristic magnetic resonance imaging and pathologic findings, points to a preferential cerebellar involvement in this disease. A relative increase in the perfusion to the basal ganglia correlated with the magnetic resonance imaging abnormalities, highly resembling that of Hallervorden-Spatz disease in one of the males, at this site. PMID:15664778

Kóbor, Jeno; Javaid, Ahmad; Omojola, Matthew F

2005-02-01

99

Normative values for testicular descent from infancy to adulthood.  

PubMed

Measurements of testicular descent and volume were performed on 100 newborns and 144 older children and adults. Mean values of testicular descent were determined for age as well as for Tanner pubertal stage, establishing normative values. We later used these normative values for testicular descent to evaluate subjects who had undergone treatment for cryptorchidism many years previously. These normative values are useful both for the evaluation and follow-up of cryptorchid, suboptimally descended, and retractile testes, as well as for the evaluation and follow-up of therapy, and may prove especially useful in the decision for therapeutic intervention with suboptimally descended testes. PMID:7903267

Sack, J; Reichman, B; Fix, A

1993-01-01

100

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

ERIC Educational Resources Information Center

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…

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

2008-01-01

101

Orion Entry, Descent, and Landing Simulation  

NASA Technical Reports Server (NTRS)

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.

Hoelscher, Brian R.

2007-01-01

102

Distributed Method to Optimal Profile Descent  

NASA Astrophysics Data System (ADS)

Current ground automation tools for Optimal Profile Descent (OPD) procedures utilize path stretching and speed profile change to maintain proper merging and spacing requirements at high traffic terminal area. However, low predictability of aircraft's vertical profile and path deviation during decent add uncertainty to computing estimated time of arrival, a key information that enables the ground control center to manage airspace traffic effectively. This paper uses an OPD procedure that is based on a constant flight path angle to increase the predictability of the vertical profile and defines an OPD optimization problem that uses both path stretching and speed profile change while largely maintaining the original OPD procedure. This problem minimizes the cumulative cost of performing OPD procedures for a group of aircraft by assigning a time cost function to each aircraft and a separation cost function to a pair of aircraft. The OPD optimization problem is then solved in a decentralized manner using dual decomposition techniques under inter-aircraft ADS-B mechanism. This method divides the optimization problem into more manageable sub-problems which are then distributed to the group of aircraft. Each aircraft solves its assigned sub-problem and communicate the solutions to other aircraft in an iterative process until an optimal solution is achieved thus decentralizing the computation of the optimization problem.

Kim, Geun I.

103

Automation for Accommodating Fuel-Efficient Descents in Constrained Airspace  

NASA Technical Reports Server (NTRS)

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.

Coopenbarger, Richard A.

2010-01-01

104

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

National Technical Information Service (NTIS)

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 m...

R. Sostaric

2010-01-01

105

Ascent/descent ancillary data production user's guide  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

106

Active force perception depends on cerebellar function  

PubMed Central

Damage to the cerebellum causes characteristic movement abnormalities but is thought to have minimal impact on somatosensory perception. Traditional clinical assessments of patients with cerebellar lesions reveal no perceptual deficits despite the fact that the cerebellum receives substantial somatosensory information. Given that abnormalities have been reported in predicting the visual consequences of movement, we suspect that the cerebellum broadly participates in perception when motor output is required (i.e., active perception). Thus we hypothesize that cerebellar integrity is essential for somatosensory perception that requires motor activity, but not passive somatosensory perception. We compared the perceptual acuity of human cerebellar patients to that of healthy control subjects in several different somatosensory perception tasks with minimal visual information. We found that patients were worse at active force and stiffness discrimination but similar to control subjects with regard to passive cutaneous force detection, passive proprioceptive detection, and passive proprioceptive discrimination. Furthermore, the severity of movement symptoms as assessed by a clinical exam was positively correlated with impairment of active force perception. Notably, within the context of these perceptual tasks, control subjects and cerebellar patients displayed similar movement characteristics, and hence differing movement strategies are unlikely to underlie the differences in perception. Our results are consistent with the hypothesis that the cerebellum is vital to sensory prediction of self-generated movement and suggest a general role for the cerebellum in multiple forms of active perception. PMID:22190620

Bhanpuri, Nasir H.; Okamura, Allison M.

2012-01-01

107

Developmental dyslexia: the cerebellar deficit hypothesis  

Microsoft Academic Search

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

Roderick I Nicolson; Angela J Fawcett; Paul Dean

2001-01-01

108

Cerebellar contribution to mental rotation: a cTBS study.  

PubMed

A cerebellar role in spatial information processing has been advanced even in the absence of physical manipulation, as occurring in mental rotation. The present study was aimed at investigating the specific involvement of left and right cerebellar hemispheres in two tasks of mental rotation. We used continuous theta burst stimulation to downregulate cerebellar hemisphere excitability in healthy adult subjects performing two mental rotation tasks: an Embodied Mental Rotation (EMR) task, entailing an egocentric strategy, and an Abstract Mental Rotation (AMR) task entailing an allocentric strategy. Following downregulation of left cerebellar hemisphere, reaction times were slower in comparison to sham stimulation in both EMR and AMR tasks. Conversely, identical reaction times were obtained in both tasks following right cerebellar hemisphere and sham stimulations. No effect of cerebellar stimulation side was found on response accuracy. The present findings document a specialization of the left cerebellar hemisphere in mental rotation regardless of the kind of stimulus to be rotated. PMID:23771602

Picazio, Silvia; Oliveri, Massimiliano; Koch, Giacomo; Caltagirone, Carlo; Petrosini, Laura

2013-12-01

109

Optimization of aerobrake assisted descent trajectories at Mars  

Microsoft Academic Search

This paper examines considerations pertinent to the use and design of Martian aerobraking descent vehicles having lifting characteristics. It focuses on optimizing descent trajectories to maximize the cross range of an aerobrake vehicle which has a maximum lift-to-drag ratio of 1.2 and ballistic coefficient of 28 lb\\/sq ft. Cross range translates into the capability of the vehicle to reach desired

Michael Cupples; Jill Nordwall; Stephen Ledoux; Theron Ruff; Gordon Woodcock

1991-01-01

110

Significance testing for direct identity-by-descent mapping  

Microsoft Academic Search

summary Direct identity-by-descent mapping is a technique for narrowing down the location of the gene or genes responsible for a given genetic disease to small segments of the genome. The technique involves DNA comparisons between pairs of affected individuals. The data generated are in the form of matching segments of the genome, representing regions likely to be identical-by-descent (IBD). Regions

G. R. GRANT; E. MANDUCHI; V. G. CHEUNG; W. J. EWENS

1999-01-01

111

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

Microsoft Academic Search

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

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

2011-01-01

112

Asymptotic Analysis of Numerical Steepest Descent with Path Approximations  

Microsoft Academic Search

We propose a variant of the numerical method of steepest descent for oscillatory integrals by using a low-cost explicit polynomial\\u000a approximation of the paths of steepest descent. A loss of asymptotic order is observed, but in the most relevant cases the\\u000a overall asymptotic order remains higher than a truncated asymptotic expansion at similar computational effort. Theoretical\\u000a results based on number

Andreas Asheim; Daan Huybrechs

2010-01-01

113

Cerebellar atrophy without cerebellar cortex hyperintensity in infantile neuroaxonal dystrophy (INAD) due to PLA2G6 mutation.  

PubMed

Infantile neuroaxonal dystrophy (INAD) is a rare neurodegenerative disorder characterized by infantile onset and rapid progression of psychomotor regression and hypotonia evolving into spasticity. The neuroradiologic hallmark of the disease is represented by cerebellar atrophy and signal hyperintensity in the cerebellar cortex on MR T2-weighted images. We report a 2-year-old boy with psychomotor regression and hypotonia carrying a homozygous 5' splice site mutation in PLA2G6 gene, whose brain MRI revealed cerebellar atrophy with normal cerebellar cortex signal intensity. The absence of the signal hyperintensity of the cerebellar cortex does not rule out the diagnosis of INAD. PMID:17254819

Biancheri, Roberta; Rossi, Andrea; Alpigiani, Giannina; Filocamo, Mirella; Gandolfo, Carlo; Lorini, Renata; Minetti, Carlo

2007-05-01

114

Entry descent and landing systems for future missions  

NASA Astrophysics Data System (ADS)

In 2005, the Huygens probe, designed by Thales Alenia Space, France, successfully completed its entry and descent in Titan's atmosphere. In the frame of the Aurora Exploration Program, ESA has initiated industrial studies for the ExoMars mission. The Thales Alenia Space France-led consortium was awarded the contract for the design, development and manufacturing of the Entry and Descent System under Thales Alenia Space—Italy mission prime. Huygens and ExoMars constitute major European milestones in the field of atmospheric entry and descent. Eight out of the ten bodies larger than Mercury in the Solar System have a significant atmosphere to descent in, either to reach a solid surface, or to explore the atmosphere itself. The gained experience in Entry Descent and Landing design will enhance European industry capability to contribute to future planetary exploration missions. This paper assesses the different environments and conditions that Entry Descent and Landing Systems will meet. It discusses how Europe's Huygens and ExoMars experience will apply in such environments and identifies the critical technologies needed to complement it. It concludes on the elements of a roadmap for the related technological development.

Poncy, J.; Lebleu, D.; Arfi, P.; Schipper, A. M.

2010-07-01

115

Cerebellar zones: history, development, and function.  

PubMed

The longitudinal and transverse zonal arrangement of axonal projections to and from the cerebellum, even more than the well-known laminar cytoarchitecture, is the hallmark of cerebellar anatomy. No model of cerebellar function, whether in motor control, cognition, or emotion, will be complete without understanding the development and function of zones. To this end, a special issue of this journal is dedicated to zones, and the purpose of this article is to summarize the research and review articles that are contained within. The special issue begins by considering some of the very first studies in the 1960s and 1970s that led to our modern understanding of this unique and defining anatomical substructure. Then, it considers the molecular analogs of longitudinal zones in the form of stripes in the cerebellar cortex and related sub-areas in the deep cerebellar nuclei, and it includes studies on the genetic underpinnings of stripes and zones. Several articles address the evolution of both embryonic clusters and adult zones across vertebrate species, and others discuss the functional and clinical relevance of zones. While we do not yet fully understand the role of zones with respect to motor behavior in all of its complexities, cerebellar function is clearly modular, and combinatorial models of complex motor movements based on multi-purpose modules are beginning to emerge. This special issue, by refocusing attention on this fundamental organization of the cerebellum, sets the stage for future studies that will more fully reveal the cellular, developmental, behavioral, and clinical relevance of zones. PMID:21822545

Oberdick, John; Sillitoe, Roy V

2011-09-01

116

Posterior fossa syndrome after cerebellar stroke.  

PubMed

Posterior fossa syndrome (PFS) due to vascular etiology is rare in children and adults. To the best of our knowledge, PFS due to cerebellar stroke has only been reported in patients who also underwent surgical treatment of the underlying vascular cause. We report longitudinal clinical, neurocognitive and neuroradiological findings in a 71-year-old right-handed patient who developed PFS following a right cerebellar haemorrhage that was not surgically evacuated. During follow-up, functional neuroimaging was conducted by means of quantified Tc-99m-ECD SPECT studies. After a 10-day period of akinetic mutism, the clinical picture developed into cerebellar cognitive affective syndrome (CCAS) with reversion to a previously learnt accent, consistent with neurogenic foreign accent syndrome (FAS). No psychometric evidence for dementia was found. Quantified Tc-99m-ECD SPECT studies consistently disclosed perfusional deficits in the anatomoclinically suspected but structurally intact bilateral prefrontal brain regions. Since no surgical treatment of the cerebellar haematoma was performed, this case report is presumably the first description of pure, "non-surgical vascular PFS". In addition, reversion to a previously learnt accent which represents a subtype of FAS has never been reported after cerebellar damage. The combination of this unique constellation of poststroke neurobehavioural changes reflected on SPECT shows that the cerebellum is crucially implicated in the modulation of neurocognitive and affective processes. A decrease of excitatory impulses from the lesioned cerebellum to the structurally intact supratentorial network subserving cognitive, behavioural and affective processes constitutes the likely pathophysiological mechanism underlying PFS and CCAS in this patient. PMID:23575947

Mariën, Peter; Verslegers, Lieven; Moens, Maarten; Dua, Guido; Herregods, Piet; Verhoeven, Jo

2013-10-01

117

A descent of the aurora over Lapland  

NASA Astrophysics Data System (ADS)

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

Whiter, Daniel; Partamies, Noora

2014-05-01

118

Mars Descent Imager (MARDI) on the Mars Polar Lander  

NASA Astrophysics Data System (ADS)

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

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

2001-08-01

119

Design of automation tools for management of descent traffic  

NASA Technical Reports Server (NTRS)

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

Erzberger, Heinz; Nedell, William

1988-01-01

120

Isolated rhomboencephalosynapsis - a rare cerebellar anomaly  

PubMed Central

Summary Background: Rhomboencephalosynapsis (RES, RS) is a unique entity usually recognized in infancy based on neuroimaging. Cerebellar fusion and absence of cerebellar vermis is often associated with supratentorial findings. Since now there are about 50 cases described worldwide, with approximately 36 patients diagnosed by MRI. The authors present the first in Poland case of this uncommon malformation and review the literature. Case Report: The authors describe a 28-month-old-girl with microcephaly and proper psychomotor development. The family history was unrelevant. Based on MRI the congenital malformation of posterior fossa-rhombencephalosynapsis was confirmed Conclusions: Presented patient is a typical example of MRI usefulness especially in patients with RES. RES symptoms are mild and that is why the diagnosis is usually made only in adulthood. PMID:22802865

Paprocka, Justyna; Jamroz, Ewa; Scieszka, Ewa; Kluczewska, Ewa

2012-01-01

121

Cerebellar Dysfunction in a Patient with HIV  

PubMed Central

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

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

2014-01-01

122

Cerebellar secretin modulates eyeblink classical conditioning.  

PubMed

We have previously shown that intracerebellar infusion of the neuropeptide secretin enhances the acquisition phase of eyeblink conditioning (EBC). Here, we sought to test whether endogenous secretin also regulates EBC and to test whether the effect of exogenous and endogenous secretin is specific to acquisition. In Experiment 1, rats received intracerebellar infusions of the secretin receptor antagonist 5-27 secretin or vehicle into the lobulus simplex of cerebellar cortex immediately prior to sessions 1-3 of acquisition. Antagonist-infused rats showed a reduction in the percentage of eyeblink CRs compared with vehicle-infused rats. In Experiment 2, rats received intracerebellar infusions of secretin or vehicle immediately prior to sessions 1-2 of extinction. Secretin did not significantly affect extinction performance. In Experiment 3, rats received intracerebellar infusions of 5-27 secretin or vehicle immediately prior to sessions 1-2 of extinction. The secretin antagonist did not significantly affect extinction performance. Together, our current and previous results indicate that both exogenous and endogenous cerebellar secretin modulate acquisition, but not extinction, of EBC. We have previously shown that (1) secretin reduces surface expression of the voltage-gated potassium channel ?-subunit Kv1.2 in cerebellar cortex and (2) intracerebellar infusions of a Kv1.2 blocker enhance EBC acquisition, much like secretin. Kv1.2 is almost exclusively expressed in cerebellar cortex at basket cell-Purkinje cell pinceaus and Purkinje cell dendrites; we propose that EBC-induced secretin release from PCs modulates EBC acquisition by reducing surface expression of Kv1.2 at one or both of these sites. PMID:25403455

Fuchs, Jason R; Robinson, Gain M; Dean, Aaron M; Schoenberg, Heidi E; Williams, Michael R; Morielli, Anthony D; Green, John T

2014-12-01

123

Topography of Cerebellar Deficits in Humans  

Microsoft Academic Search

The cerebellum is a key-piece for information processing and is involved in numerous motor and nonmotor activities, thanks\\u000a to the anatomical characteristics of the circuitry, the enormous computational capabilities and the high connectivity to other\\u000a brain areas. Despite its uniform cytoarchitecture, cerebellar circuitry is segregated into functional zones. This functional\\u000a parcellation is driven by the connectivity and the anatomo-functional heterogeneity

Giuliana Grimaldi; Mario Manto

124

Cerebellar and thalamic stimulation treatment for epilepsy  

Microsoft Academic Search

The present chapter describes the most important available experimental and clinical evidence on the role of electrical stimulation\\u000a of the cerebellum or the thalamus in the control of epilepsy. Cerebellum serves as an integrator of sensory information and\\u000a regulator of motor coordinating and training. The sole output of the cerebellum is inhibitory Purkinje cell projections to\\u000a deep cerebellar nuclei in

Gregory L. Krauss; M. Z. Koubeissi

125

Cerebellar-parietal connections underpin phonological storage.  

PubMed

Previous research has accumulated convincing evidence to show that the human cerebellum contributes to the short-term storage of verbal information, but its specific role in brain networks involved in phonological storage remains uncertain. In a randomized, crossover and sham-controlled design, we here combined transcranial direct current stimulation (tDCS), applied to the right cerebellum, with fMRI to investigate systematically the contribution of the human cerebellum to encoding, maintenance, and retrieval of verbal information. After anodal, but not cathodal, tDCS, we found a reduced item recognition capacity together with an attenuated neural signal from the right cerebellar lobule VIIb, specifically during the late encoding phase. Within this phase, tDCS furthermore affected task-associated functional connections between right cerebellar lobule VIIb and the posterior parietal cortex. These findings suggest that the right cerebellar lobule VIIb interacts with the posterior parietal cortex, specifically during the late stages of verbal encoding, when verbal information enters phonological storage. PMID:24695720

Macher, Katja; Böhringer, Andreas; Villringer, Arno; Pleger, Burkhard

2014-04-01

126

Midbrain infarction causing oculomotor nerve palsy and ipsilateral cerebellar ataxia.  

PubMed

We herein report the case of an 81-year-old woman with midbrain infarction causing pupil-sparing oculomotor nerve palsy with ipsilateral cerebellar ataxia. The lesion was located at the rostral end of the decussation of the superior cerebellar peduncle touching the dorsal side, further caudal and dorsal to causal lesions of Claude's syndrome, which presented as oculomotor palsy and contralateral cerebellar ataxia. This is the third report of midbrain infarction causing partial oculomotor nerve palsy with ipsilateral cerebellar ataxia. It may be possible to establish this entity as a new syndrome following the accumulation of more cases. PMID:25224204

Tokunaga, Makoto; Fukunaga, Kimiko; Nakanishi, Ryoji; Watanabe, Susumu; Yamanaga, Hiroaki

2014-01-01

127

Crew Procedures for Continuous Descent Arrivals Using Conventional Guidance  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

128

Mars Smart Lander Simulations for Entry, Descent, and Landing  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

129

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

NASA Technical Reports Server (NTRS)

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.

Martinez, Elmain M.; Winterhalter, Daniel

2012-01-01

130

Thermoelastic model for the descent of avalanches and landslides  

NASA Astrophysics Data System (ADS)

A wedge-shaped mass of snow or soil on a flat mountain slope is simulated in a connected formulation by a thermoelastic medium acted upon by gravity, a uniform surface load, and a heat flux. An exact solution of the problem of equilibrium of the mass is obtained. Two criteria for the descent of an avalanche or a landslide are derived from the conditions of impossibility of equilibrium. This result can be used to predict soil landslides and the descent of avalanches in the mountains.

Chernyshov, A. D.

2012-11-01

131

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

132

A taxonomy of descent algorithms for nonlinear programs and variational inequalities  

E-print Network

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

Patriksson, Michael

133

Simulation Results for Airborne Precision Spacing along Continuous Descent Arrivals  

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

134

LANDER program manual: A lunar ascent and descent simulation  

NASA Technical Reports Server (NTRS)

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.

1988-01-01

135

A mathematical model and descent algorithm for bilevel traffic management  

E-print Network

A mathematical model and descent algorithm for bilevel traffic management Michael Patriksson for strategic traffic management, formulated and analyzed as a mathematical program with equilibrium constraints such traffic management actions as traffic signal setting, network design, and congestion pricing. The lower

Patriksson, Michael

136

A mathematical model and descent algorithm for bilevel traffic management  

E-print Network

A mathematical model and descent algorithm for bilevel traffic management Michael Patriksson and R management actions as traffic signal setting, network design, and congestion pricing. The lower-level problem, and representations of traffic flows and management actions in both link­route and link­node space. For this model, we

Patriksson, Michael

137

A Mathematical Model and Descent Algorithm for Bilevel Traffic Management  

E-print Network

A Mathematical Model and Descent Algorithm for Bilevel Traffic Management Michael Patriksson · R@math.chalmers.se · rtr@math.washington.edu We provide a new mathematical model for strategic traffic management types of control (upper-level) variables, which may be used to describe such traffic management actions

Patriksson, Michael

138

A random coordinate descent algorithm for optimization problems ...  

E-print Network

physical memory and enormous complexity of the gradient update can also be an obstacle for full ... main differences between all variants of coordinate descent methods consist of the criterion of ... We work in the space Rn composed of column vectors. For x, y ..... Based on Exercise 10.6 in [25] we state the following lemma:.

2013-02-06

139

Operation of CONSERT aboard Rosetta during the descent of Philae  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

140

Reference Airspeed Setting For Time Constrained Descent at Idle Thrust  

E-print Network

. CDO is defined as 'an aircraft operating technique aided by appropriate airspace and procedure design trajectory application where the air traffic controller will ask an aircraft to overfly a meter fix, this clearance is assumed to be given after the Top Of Descent (TOD) of the aircraft. The aircraft is assumed

Boyer, Edmond

141

Unsupervised Change Detection of Satellite Images Using Local Gradual Descent  

Microsoft Academic Search

In this paper, we propose a novel technique for unsupervised change detection of multitemporal satellite images using Gaussian mixture model (GMM), local gradual descent, and $k$ -means clustering. Data distribution of the difference image is first modeled by bimodal GMM with “changed” and “unchanged” components. The neighborhood data around each pixel form a sample and are modified by the so-called

Zeki Yetgin

2012-01-01

142

Self-Hatred in Americans of African Descent.  

ERIC Educational Resources Information Center

In spite of attempts to destigmatize themselves with the "black is beautiful" rhetoric, efforts by Americans of African descent to disavow their imputed inferiority have not been successful. The black is reacted to as a handicapped person by the white American. Whites look with disdain on black-white sexual relationships, black language, and…

Vontress, Clemmont E.

143

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

NASA Technical Reports Server (NTRS)

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.

Sostaric, Ronald

2010-01-01

144

Optical diffusion tomography by iterative-coordinate-descent  

E-print Network

- netic resonance imaging (MRI) systems. Furthermore, in an optical imaging application a hostOptical diffusion tomography by iterative- coordinate-descent optimization in a Bayesian framework. © 1999 Optical Society of America [S0740-3232(99)01410-6] OCIS codes: 100.3010, 100.3190, 100.6950, 170

145

Pregnant Women of Mexican Descent: Constructions of Motherhood  

Microsoft Academic Search

Past research related to pregnancy outcomes has tended to have a bio-medical focus. More recent research has begun to explore possible social and cultural influences on birth outcomes. Qualitative interviews were conducted with 28 pregnant women of Mexican descent in the Texas\\/Mexico border region to begin to describe the social and cultural contexts of pregnancy of women of Mexican ancestry.

Faith W. Lucas

2010-01-01

146

Origin of INSL3-mediated testicular descent in therian mammals.  

PubMed

Testicular descent is a unique physiological adaptation found in therian mammals allowing optimal spermatogenesis below core body temperature. Recent studies show that INSL3, produced by Leydig cells, and its receptor LGR8 (RXFP2) are essential for mediating the transabdominal phase of testicular descent during early development. However, the origin and genetic basis for this physiological adaptation is not clear. Using syntenic mapping and the functional characterization of contemporary and resurrected relaxin family hormones, we show that derivation of INSL3-mediated testicular descent involved the duplication of an ancestral RLN3-like gene that encodes an indiscriminate ligand for LGR7 (RXFP1) and LGR8. This event was followed by acquisition of the LGR7-selective characteristics by a daughter gene (RLN3) prior to the evolution of the common ancestor of monotremes, marsupials, and placentals. A subsequent mutation of the other daughter gene (INSL3) occurred before the emergence of therian mammals, which then led to the derivation of the reciprocal LGR8-specific characteristics of INSL3. The stepwise evolution of these independent signaling pathways through gene duplication and subsequent divergence is consistent with Darwinian theory of selection and adaptation, and the temporal proximity suggests an association between these genetic events and the concurrent evolution of testicular descent in ancestral therian mammals. PMID:18463305

Park, Jae-Il; Semyonov, Jenia; Chang, Chia Lin; Yi, Wei; Warren, Wesley; Hsu, Sheau Yu Teddy

2008-06-01

147

Abuse against Women with Disabilities of Mexican Descent: Cultural Considerations  

ERIC Educational Resources Information Center

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

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

2008-01-01

148

Cerebellar theta burst stimulation in stroke patients with ataxia  

PubMed Central

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

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

2014-01-01

149

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

PubMed

Inborn errors of metabolism can affect the cerebellum during development, maturation and later during life. We have established criteria for pattern recognition of cerebellar abnormalities in metabolic disorders. The abnormalities can be divided into four major groups: cerebellar hypoplasia (CH), hyperplasia, cerebellar atrophy (CA), cerebellar white matter abnormalities (WMA) or swelling, and involvement of the dentate nuclei (DN) or cerebellar cortex. CH can be an isolated typical finding, as in adenylsuccinase deficiency, but is also occasionally seen in many other disorders. Differentiation from CH and CA is often difficult, as in carbohydrate deficient glycoprotein syndrome or 2-L-hydroxyglutaric acidaemia. In cases of atrophy the relationship of cerebellar to cerebral atrophy is important. WMA may be diffuse or patchy, frequently predominantly around the DN. Severe swelling of white matter is present during metabolic crisis in maple syrup urine disease. The DN can be affected by metabolite deposition, necrosis, calcification or demyelination. Involvement of cerebellar cortex is seen in infantile neuroaxonal dystrophy. Changes in DN and cerebellar cortex are rather typical and therefore most helpful; additional features should be sought as they are useful in narrowing down the differential diagnosis. PMID:9689620

Steinlin, M; Blaser, S; Boltshauser, E

1998-06-01

150

Cerebellar dysplasia and unilateral cataract in Marinesco-Sjörgen syndrome  

Microsoft Academic Search

The classic features of Marinesco-Sjögren syndrome include bilateral cataracts, cerebellar ataxia, and mental deficiency with an autosomal recessive inheritance pattern. Weakness and a variety of other characteristics are present inconsistently. A limited number of neuroimaging studies have indicated that cerebellar hypoplasia is the most common finding. We report a patient with near normal intelligence, unilateral cataract, and the previously unreported

Tracy E. Williams; Jeffrey R. Buchhalter; Michael D. Sussman

1996-01-01

151

The Cerebellum and Language: Evidence from Patients with Cerebellar Degeneration  

ERIC Educational Resources Information Center

Clinical and imaging studies suggest that the cerebellum is involved in language tasks, but the extent to which slowed language production in cerebellar patients contributes to their poor performance on these tasks is not clear. We explored this relationship in 18 patients with cerebellar degeneration and 16 healthy controls who completed measures…

Stoodley, Catherine J.; Schmahmann, Jeremy D.

2009-01-01

152

Isolated cerebellar dysarthria associated with a heat stroke  

Microsoft Academic Search

Patients presenting with heat stroke may develop an acute pancerebellar syndrome. A patient presenting with an isolated cerebellar dysarthria after a heat stroke is reported. The dysarthria lasted two weeks. An isolated cerebellar dysarthria has been previously described in lesions of the paravermal zone of the rostral cerebellum. It is suggested that this region of the cerebellum is particularly vulnerable

Mario-Ubaldo Manto

1996-01-01

153

A Speaking Task Analysis of the Dysarthria in Cerebellar Disease  

Microsoft Academic Search

Cerebellar disease affects a number of skilled movements, including those in speech. Ataxic dysarthria, the speech disorder that typically accompanies cerebellar disease, was studied by acoustic methods. Control subjects and subjects with ataxic dysarthria were recorded while performing a number of speaking tasks, including sustained vowel phonation, syllable repetition, monosyllabic word production (intelligibility test), sentence recitation, and conversation. Acoustic data

R. D. Kent; J. F. Kent; J. C. Rosenbek; H. K. Vorperian; G. Weismer

1997-01-01

154

Increased cerebellar volume and BDNF level following quadrato motor training.  

PubMed

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

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

2015-01-01

155

An integrator circuit in cerebellar cortex.  

PubMed

The brain builds dynamic models of the body and the outside world to predict the consequences of actions and stimuli. A well-known example is the oculomotor integrator, which anticipates the position-dependent elasticity forces acting on the eye ball by mathematically integrating over time oculomotor velocity commands. Many models of neural integration have been proposed, based on feedback excitation, lateral inhibition or intrinsic neuronal nonlinearities. We report here that a computational model of the cerebellar cortex, a structure thought to implement dynamic models, reveals a hitherto unrecognized integrator circuit. In this model, comprising Purkinje cells, molecular layer interneurons and parallel fibres, Purkinje cells were able to generate responses lasting more than 10 s, to which both neuronal and network mechanisms contributed. Activation of the somatic fast sodium current by subthreshold voltage fluctuations was able to maintain pulse-evoked graded persistent activity, whereas lateral inhibition among Purkinje cells via recurrent axon collaterals further prolonged the responses to step and sine wave stimulation. The responses of Purkinje cells decayed with a time-constant whose value depended on their baseline spike rate, with integration vanishing at low (< 1 per s) and high rates (> 30 per s). The model predicts that the apparently fast circuit of the cerebellar cortex may control the timing of slow processes without having to rely on sensory feedback. Thus, the cerebellar cortex may contain an adaptive temporal integrator, with the sensitivity of integration to the baseline spike rate offering a potential mechanism of plasticity of the response time-constant. PMID:23731348

Maex, Reinoud; Steuber, Volker

2013-09-01

156

Measurement of CPAS Main Parachute Rate of Descent  

NASA Technical Reports Server (NTRS)

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.

Ray, Eric S.

2011-01-01

157

Computations of diabatic descent in the stratospheric polar vortex  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

158

Nicotine Increases Cerebellar Activity during Finger Tapping  

PubMed Central

Nicotine improves performance on several cognitive and sensorimotor tasks. The neuronal mechanisms associated with these changes in performance are, however, largely unknown. Functional magnetic resonance imaging (fMRI) was used to examine the effect of nicotine on neuronal response in nineteen healthy subjects while they performed an auditory-paced finger tapping task. Subjects performed the task, after receiving either a nicotine patch or placebo treatment, in a single blind, crossover design. Compared to placebo, nicotine treatment increased response in the cerebellar vermis. Increased vermal activity, in the absence of changes in other task-related regions suggests specificity in nicotine’s effects. PMID:24358367

Wylie, Korey P.; Tanabe, Jody; Martin, Laura F.; Wongngamnit, Narin; Tregellas, Jason R.

2013-01-01

159

New evidence for the cerebellar involvement in personality traits  

PubMed Central

Following the recognition of its role in sensory-motor coordination and learning, the cerebellum has been involved in cognitive, emotional, and even personality domains. This study investigated the relationships between cerebellar macro- and micro-structural variations and temperamental traits measured by Temperament and Character Inventory (TCI). High resolution T1-weighted, and Diffusion Tensor Images of 100 healthy subjects aged 18–59 years were acquired by 3 Tesla Magnetic Resonance scanner. In multiple regression analyses, cerebellar Gray Matter (GM) or White Matter (WM) volumes, GM Mean Diffusivity (MD), and WM Fractional Anisotropy (FA) were used as dependent variables, TCI scores as regressors, gender, age, and education years as covariates. Novelty Seeking scores were associated positively with the cerebellar GM volumes and FA, and negatively with MD. No significant association between Harm Avoidance, Reward Dependence or Persistence scores and cerebellar structural measures was found. The present data put toward a cerebellar involvement in the management of novelty. PMID:24106465

Picerni, Eleonora; Petrosini, Laura; Piras, Fabrizio; Laricchiuta, Daniela; Cutuli, Debora; Chiapponi, Chiara; Fagioli, Sabrina; Girardi, Paolo; Caltagirone, Carlo; Spalletta, Gianfranco

2013-01-01

160

Age-associated changes of cytoplasmic calcium homeostasis in cerebellar granule neurons in situ: Investigation on thin cerebellar slices  

Microsoft Academic Search

Mechanisms of cytoplasmic calcium homeostasis were investigated in adult and old CBA mice. The cytoplasmic calcium concentration ([Ca2+]) was measured on fura-2\\/AM loaded granule neurons in acutely isolated cerebellar slices. The resting [Ca2+], was significantly higher in senile cerebellar granule neurons, being on average 60 ± 15 nM (n = 163) in adult and 107 ± 12 nM (n =

Sergej Kirischuk; Nana Voitenko; Platon Kostyuk; Alexej Verkhratsky

1996-01-01

161

Method for securing titanium cerebellar retractors  

PubMed Central

Background: Traditional stainless steel retractors can interfere with electromagnetic neuronavigation and intraoperative magnetic resonance imaging (ioMRI). In such cases, titanium instruments are frequently used; however, they often shift during the procedure. The authors describe a simple technique, illustrated with intraoperative photographs, for securing titanium cerebellar retractors into place to keep both the retractors and tissues in their desired locations throughout a craniotomy. Methods: Titanium retractors were used by our institute's neurosurgical service during operations utilizing electromagnetic neuronavigation or ioMRI. Once the retractor was in the desired position, a 2-0 silk suture was placed around a retractor tong and tied outside the skin. Two sutures were placed on either side of the titanium retractor in the same fashion. Results: Retractors were subsequently noted to remain in their desired position throughout the operative procedure. Conclusions: The authors describe a technique for securing titanium cerebellar retractors into their desired position during a craniotomy to minimize their movement during the procedure. This simple technique can help to eliminate a potential frequent source of surgeon frustration, and has proven to be quick to perform, safe, and practicable. PMID:24340228

Lipinski, Lindsay J.; Hoppenot, Regis G.; Fenstermaker, Robert A.; Fabiano, Andrew J.

2013-01-01

162

Increase in tonsillar germinal centre B-1 cell numbers in IgA nephropathy (IgAN) patients and reduced susceptibility to Fas-mediated apoptosis  

PubMed Central

IgAN is a common form of primary glomerulonephritis and also a disease of tonsillar focal infection. The comprehensive mechanism underlying this disease remains to be defined. To better understand its pathogenesis, we investigated tonsillar CD5+ B cells (B-1 cells) with respect to IgA synthesis. Germinal centre (GC) B cells were isolated from the tonsils of IgAN patients and the number of B-1 cells in the GC determined by flow cytometry. GC B-1 and B-2 (CD5? B) cells were purified by cell sorter, the cells were incubated with agonist anti-CD40 MoAb and the ability for antibody production by B-1 and B-2 cells determined by ELISPOT assay. GC B-1 cells and B-2 cells were incubated with agonist anti-Fas MoAb, and apoptosis in GC B-1 cells and B-2 cells was analysed by flow cytometry. Although B-1 cells do not usually take part in the GC reaction, an increase in B-1 cell numbers was observed in the GC of tonsils from IgAN patients. These B-1 cells were likely IgA1 antibody-producing cells, since the prominent IgA subclass in IgAN is generally considered to be IgA1. Although Fas-dependent apoptosis is essential for the elimination of activated B cells, these B-1 cells showed a reduced susceptibility to Fas-mediated apoptosis. It is conceivable that activated B-1 cells may survive in the GC due to impaired apoptosis and thus produce abnormal antibodies. These findings suggest that the immune responses of B-1 cells in the tonsillar GC could thus have an impact on the pathogenesis of IgAN. PMID:11207662

Kodama, S; Suzuki, M; Arita, M; Mogi, G

2001-01-01

163

Efficient sensor placement optimization using gradient descent and probabilistic coverage.  

PubMed

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

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

2014-01-01

164

Efficient Sensor Placement Optimization Using Gradient Descent and Probabilistic Coverage  

PubMed Central

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

Akbarzadeh, Vahab; Levesque, Julien-Charles; Gagne, Christian; Parizeau, Marc

2014-01-01

165

Cerebellar dysplasia and unilateral cataract in Marinesco-Sjögren syndrome.  

PubMed

The classic features of Marinesco-Sjögren syndrome include bilateral cataracts, cerebellar ataxia, and mental deficiency with an autosomal recessive inheritance pattern. Weakness and a variety of other characteristics are present inconsistently. A limited number of neuroimaging studies have indicated that cerebellar hypoplasia is the most common finding. We report a patient with near normal intelligence, unilateral cataract, and the previously unreported magnetic resonance imaging findings of cerebellar dysplasia, arachnoid cyst, and absent septum pellucidum. A review of the literature suggests significant heterogeneity in the Marinesco-Sjögren syndrome. PMID:8703231

Williams, T E; Buchhalter, J R; Sussman, M D

1996-02-01

166

Flight-Management Algorithm for Fuel-Conservative Descents  

NASA Technical Reports Server (NTRS)

Federal Aviation Administration has developed an automated time-based metering form of air traffic control for arrivals into terminal area called local flow management/profile descent (LFM/PD). LFM/PD saves fuel by matching airplane arrival flow to airport acceptance rate through time-control computations and by allowing pilot to descend at his discretion from cruise altitude to metering fix in an idle-thrust, clean configuration (landing gear up, flaps zero, speed brakes retracted).

Knox, C. E.; Cannon, D. G.

1982-01-01

167

A Variable Neighbourhood Descent Algorithm for the Redundancy Allocation Problem  

Microsoft Academic Search

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

Yun-Chia Liang; Chia-Chuan Wu

168

A coordinate gradient descent method for ? 1 -regularized convex minimization  

Microsoft Academic Search

In applications such as signal processing and statistics, many problems involve finding sparse solutions to under-determined\\u000a linear systems of equations. These problems can be formulated as a structured nonsmooth optimization problems, i.e., the problem\\u000a of minimizing ?\\u000a 1-regularized linear least squares problems. In this paper, we propose a block coordinate gradient descent method (abbreviated\\u000a as CGD) to solve the more

Sangwoon Yun; Kim-Chuan Toh

2011-01-01

169

Directed Aerial Descent Behavior in African Canopy Ants (Hymenoptera: Formicidae)  

Microsoft Academic Search

Several species of neotropical ants direct their aerial descent toward tree trunks during a fall from the forest canopy. The\\u000a primary goal of this study was to determine if afrotropical arboreal ants exhibit similar gliding behavior. Ants were collected\\u000a from nine tree crowns in late secondary forest at a hydrocarbon extraction site near Gamba, Gabon. Of the 32 species tested,

S. P. Yanoviak; B. L. Fisher; A. Alonso

2008-01-01

170

Scaling Up Coordinate Descent Algorithms for Large ?1 Regularization Problems  

SciTech Connect

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.

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

2012-07-03

171

Direct IBD mapping: identical-by-descent mapping without genotyping  

Microsoft Academic Search

Direct identical-by-descent (IBD) mapping is a technique, that combines genomic mismatch scanning (GMS) and DNA microarray technology, for mapping regions shared IBD between two individuals without locus-by-locus genotyping or sequencing. The lack of reagents has limited its widespread application. In particular, two key reagents have been limiting, 1) mismatch repair proteins MutS, L and H, and 2) genomic microarrays for

Denis Smirnov; Alan Bruzel; Michael Morley; Vivian G. Cheunga

2004-01-01

172

Free-falls and parachute descents in the standard atmosphere  

NASA Technical Reports Server (NTRS)

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

Webster, A P

1947-01-01

173

Data-Analysis System for Entry, Descent, and Landing  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

174

Factors Associated with Sleep Disturbance in Women of Mexican Descent  

PubMed Central

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

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

2014-01-01

175

Inflammatory Bowel Disease in Children of Middle Eastern Descent  

PubMed Central

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

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

2014-01-01

176

Airborne Management of Traffic Conflicts in Descent With Arrival Constraints  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

177

Anatomical and physiological evidence for a cerebellar nucleo-cortical projection in the cat.  

PubMed

Combined neuroanatomical and electrophysiological experiments were performed to test the hypothesis that axon collaterals of neurons in the cerebellar nuclei project to the cerebellar cortex in cats. The anatomical studies demonstrated that (a) following the injection of tritiated leucine into the deep cerebellar nuclei, labeled fibers could be traced into the granular layer of the cerebellar cortex, and (b) following the injection of horseradish peroxidase into the cerebellar cortex, retrogradely labeled horseradish peroxidase-positive neurons were identified in the deep nuclei. The electrophysiological experiments confirmed the anatomical findings. Neurons in the dentate and interposed nuclei, identified by their antidromic activation from the brachium conjunctivum, could also be activated antidromically from the cerebellar surface. Collision experiments demonstrated that projections from the deep cerebellar nuclei to the cerebellar cortex are in part collaterals of efferent neurons projecting through the brachium conjunctivum. Care was taken to ensure that all recordings were obtained from the region of cell somata in order to minimize the likelihood of recording from neuronal elements passing through the cerebellar nuclei. These combined neuroanatomical and electrophysiological studies provide strong evidence supporting the existence of a collateral system from cerebellar output neurons to the cerebellar cortex. The existence of this collateral system emphasizes that the cerebellar cortex and cerebellar nuclei may comprise a functional unit in which these collaterals may serve as a substrate for feedback control of the cerebellar cortex by the cerebellar output. PMID:11370232

Tolbert, D L; Bantli, H; Bloedel, J R

1976-06-01

178

Executive functions and cerebellar development in children.  

PubMed

This article examines the role of the cerebellum in processing executive functions in developmental age. The areas implicated in its elaboration are interconnected in a network that includes the prefrontal cortex, the basal ganglia, and the cerebellum. Implementation of the capacities to plan and to control corresponds to the development of the network and its structures. The development, from an evolutionary point of view, of the most recent parts of the cerebellum and of its connections with the prefrontal cortex is tied to the crucial role that it plays in an inexorable way in action execution with implicit mechanisms of anticipation and control. Deficits in executive functions are present in many cerebellar pathologies and there is also an important link between motor development and the development of many higher-order cognitive and functional domains. Further studies are needed to clarify the role of the cerebellum in executive functions both in pathological or normal conditions in the developmental age. PMID:23745837

Riva, Daria; Cazzaniga, Fabiana; Esposito, Silvia; Bulgheroni, Sara

2013-01-01

179

On-Line Learning Theory of Soft Committee Machines with Correlated Hidden Units —Steepest Gradient Descent and Natural Gradient Descent  

NASA Astrophysics Data System (ADS)

The permutation symmetry of the hidden units in multilayer perceptrons causes the saddle structure and plateaus of the learning dynamics in gradient learning methods. The correlation of the weight vectors of hidden units in a teacher network is thought to affect this saddle structure, resulting in a prolonged learning time, but this mechanism is still unclear. In this paper, we discuss it with regard to soft committee machines and on-line learning using statistical mechanics. Conventional gradient descent needs more time to break the symmetry as the correlation of the teacher weight vectors rises. On the other hand, no plateaus occur with natural gradient descent regardless of the correlation for the limit of a low learning rate. Analytical results support these dynamics around the saddle point.

Inoue, Masato; Park, Hyeyoung; Okada, Masato

2003-04-01

180

Novel Approaches to Studying the Genetic Basis of Cerebellar Development  

PubMed Central

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

Sajan, Samin A.; Waimey, Kathryn E.

2010-01-01

181

Past, Present and Future Therapeutics for Cerebellar Ataxias  

PubMed Central

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

Marmolino, D; Manto, M

2010-01-01

182

Genetics Home Reference: VLDLR-associated cerebellar hypoplasia  

MedlinePLUS

... cerebellar hypoplasia? This condition is inherited in an autosomal recessive pattern, which means both copies of the gene ... mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated ...

183

Takotsubo-Like Myocardial Dysfunction Accompanied with Cerebellar Hemorrhage  

PubMed Central

We report a 71-year-old woman with takotsubo-like myocardial dysfunction accompanied with cerebellar hemorrhage. On admission time, although she was unconscious by cerebellar hemorrhage, no obvious heart failure and serological disorder were observed. Three days later, operation for extraventricular drainage was performed. However, conscious level did not change. Four days after admission, the change of electrocardiogram wave pattern and the decrement of heart wall motion were detected. These findings revealed takotsubo-like myocardial dysfunction had occurred. Physical stresses by cerebellar hemorrhage and cranial operation might cause cardiac disorder. This is a remarkable case of takotsubo-like myocardial dysfunction, which is brought about cerebellar hemorrhage against subarachnoid hemorrhage. PMID:22953089

Tempaku, Akira; Kanda, Tsugiyasu

2012-01-01

184

Original Research Cerebellar Transcranial Magnetic Stimulation: The Role of Coil  

E-print Network

: Received 2 March 2014 Received in revised form 26 April 2014 Accepted 29 April 2014 Available online xxx Keywords: Cerebellum TMS Cerebello brain inhibition Cerebellar brain inhibition TMS coil geometry Deep TMS

Miall, Chris

185

A Case of Cerebellar Ataxia Associated with HIV Infection.  

PubMed

Cerebellar complications of HIV infection primarily manifested in ataxia, usually arise as the result of cerebellar lesions due to opportunistic infections, vasculitis or neoplastic processes. A 28 year old female known to have HIV infection for last four years, presented to our hospital with progressive unsteadiness in walking, slurring of speech and intention tremors for the last two months. There was no family history of similar complaints, and she was on Anti retroviral treatment for last one and a half years. The results of examination were notable for severe dysarthria, slow saccades, a conspicuous dysmetria and dysdiadokokinesia. She had no cognitive, sensory or motor deficits. MRI revealed diffuse cerebellar atrophy. Extensive laboratory work up failed to disclose a cause for subacute ataxia. Isolated cerebellar degeneration in an HIV patient is rare and should prompt a diagnostic work up. PMID:24759449

Anand, Kuljeet Singh; Wadhwa, Ankur; Garg, Jyoti

2014-09-01

186

Biliary atresia and cerebellar hypoplasia in polysplenia syndrome  

Microsoft Academic Search

We report a 3.5-month-old boy with polysplenia syndrome who demonstrated hemiazygos continuation of the inferior vena cava, extrahepatic biliary atresia, multiple splenunculi, bowel malrotation, and the rare finding of brainstem and cerebellar hypoplasia. A possible pathogenesis for cerebellar hypoplasia in this syndrome is suggested after review of the literature. The importance of seeking associated anomalies in biliary atresia, which may

Kurt Vanderdood; Bart Op de Beeck; Brigitte Desprechins; Michel Osteaux

2003-01-01

187

Systems Biology Perspectives on Cerebellar Long-Term Depression  

Microsoft Academic Search

Long-term depression (LTD) at parallel fiber-Purkinje cell (PF-PC) synapses is thought to be the cellular correlate of cerebellar associative learning. The molecular processes are, in brief, phosphorylation of AMPA-type glutamate receptors (AMPARs) and their subsequent removal from the surface of the PF-PC synapse. In order to elucidate the fundamental mechanisms for cerebellar LTD and further the understanding of its computational

Hideaki Ogasawara; Tomokazu Doi; Mitsuo Kawato

2008-01-01

188

Cerebellar contributions to verbal working memory: beyond cognitive theory  

Microsoft Academic Search

Neuropsychological findings together with recent advances in neuroanatomical and neuroimaging techniques have spurred the\\u000a investigation of cerebellar contributions to cognition. One cognitive process that has been the focus of much research is\\u000a working memory, in particular its verbal component. Influenced by Baddeley’s cognitive theory of working memory, cerebellar\\u000a activation during verbal working memory tasks has been predominantly attributed to the

Gal Ben-Yehudah; Sara Guediche; Julie A. Fiez

2007-01-01

189

Cerebellar atrophy without cerebellar cortex hyperintensity in infantile neuroaxonal dystrophy (INAD) due to PLA2G6 mutation  

Microsoft Academic Search

Infantile neuroaxonal dystrophy (INAD) is a rare neurodegenerative disorder characterized by infantile onset and rapid progression of psychomotor regression and hypotonia evolving into spasticity. The neuroradiologic hallmark of the disease is represented by cerebellar atrophy and signal hyperintensity in the cerebellar cortex on MR T2-weighted images. We report a 2-year-old boy with psychomotor regression and hypotonia carrying a homozygous 5?

Roberta Biancheri; Andrea Rossi; Giannina Alpigiani; Mirella Filocamo; Carlo Gandolfo; Renata Lorini; Carlo Minetti

2007-01-01

190

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

NASA Technical Reports Server (NTRS)

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

1980-01-01

191

Entry, Descent, and Landing for Human Mars Missions  

NASA Technical Reports Server (NTRS)

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.

Munk, Michelle M.; DwyerCianciolo, Alicia M.

2012-01-01

192

Powered Descent Guidance with General Thrust-Pointing Constraints  

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

193

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

194

Graham Greene's use of the christian concept of descent  

E-print Network

of wood in fi. re ('~, 'orl&s, I, 402-406) and to the diet of a sick person who must eat "fooa that is nourishing rather than delectable" (Works, I, 425). This concept of descent that z. esults in ascent to God involves paradoxes. The dazk night... "according to Saint Bernard and Saint Thomas" (Works& I, 435). The first step causes the soul to become sick; "?just as a sick man first of all loses his appetite and t. ste for all food, and nis colour changes, so li. kewise in this degree of love...

Love, Frances Ann C

2012-06-07

195

Guidance and Control During Direct-Descent Parabolic Reentry  

NASA Technical Reports Server (NTRS)

The results of studies of four reentry guidance and control techniques for the energy management of vehicles returning to the earth at escape speeds are compared in this paper. The reentry trajectories are constrained to those of direct descent, that is, where the vehicle does not leave that portion of the atmosphere where useful aerodynamic forces are available after its initial entry. The guidance techniques compared are: (1) a piloted simulator study reference trajectory techniques; 2) An automatic controller using reference trajectory techniques; 3) A predictor system employing linear prediction (perturbation) techniques; and 4) A repetitive prediction system employing rapid-time computer techniques.

Foudriat, Edwin C.; Wingrove, Rodney C.

1961-01-01

196

Regularization Paths for Generalized Linear Models via Coordinate Descent.  

PubMed

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

Friedman, Jerome; Hastie, Trevor; Tibshirani, Rob

2010-01-01

197

Regularization Paths for Generalized Linear Models via Coordinate Descent  

PubMed Central

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

Friedman, Jerome; Hastie, Trevor; Tibshirani, Rob

2010-01-01

198

The design and reconstruction of the Viking Lander descent trajectories  

NASA Technical Reports Server (NTRS)

The success of the Viking Mission is truly a major milestone in this country's planetary exploration program. This paper deals with the trajectory characteristics of the Viking Lander descent trajectories, beginning with the imposed requirements and constraints, the final preflight design based on the final hardware and operational capability, and ending with the actual performance achieved. A comparison between the predicted and actual trajectory characteristics is made to indicate the achieved accuracy and modeling fidelity. Also, estimates of the Martian environment derived from the entry-trajectory reconstruction process are presented.

Euler, E. A.; Adams, G. L.; Hopper, F. W.

1977-01-01

199

Developmental origins of diversity in cerebellar output nuclei  

PubMed Central

Background The functional integration of the cerebellum into a number of different neural systems is governed by the connection of its output axons. In amniotes, the majority of this output is mediated by an evolutionarily diverse array of cerebellar nuclei that, in mice, are derived from the embryonic rhombic lip. To understand the origins of cerebellar nucleus diversity, we have explored how nucleus development is patterned in birds, which notably lack a dentate-like nucleus output to the dorsal thalamus. Results Using targeted in ovo electoroporation of green fluorescent protein (GFP) and red fluorescent protein (RFP) in a variety of combinations and with different conditional enhancers, we show that cerebellar nuclei in chicks are produced, as in the mouse, at the rhombic lip. Furthermore, the comparison of fate-mapped neurons with molecular markers reveals a strict temporal sequence of cell fate allocation in establishing the avian lateral and medial cerebellar nuclei. In contrast to the mouse cerebellum, Lhx9 expression is confined to extracerebellar thalamic afferent nuclei corresponding to the absence, in chicks, of a dentate nucleus. Spatiotemporally targeted over-expression of Lhx9 in chick cerebellar nuclei (recapitulating in part the mammalian expression pattern) results in a loss of distinct nuclear boundaries and a change in axon initial trajectories consistent with a role for Lhx9 specifying targeting. Conclusions Our results confirm the relationship between cell fate and a fine grain temporal patterning at the rhombic lip. This suggests that the lack of a cerebellar output to the dorsal thalamus of birds corresponds with a restricted expression of the LIM-homeodomain gene Lhx9 to earlier born rhombic lip cohorts when compared to mice. The evolution of cerebellar nucleus diversity in amniotes may hence reflect a heterochronic adaptation of gene expression with respect to the sequential production of rhombic lip derivatives resulting in altered axonal targeting. PMID:24405572

2014-01-01

200

Cerebellar hypoplasia: differential diagnosis and diagnostic approach.  

PubMed

Cerebellar hypoplasia (CH) refers to a cerebellum with a reduced volume, and is a common, but non-specific neuroimaging finding. The etiological spectrum of CH is wide and includes both primary (malformative) and secondary (disruptive) conditions. Primary conditions include chromosomal aberrations (e.g., trisomy 13 and 18), metabolic disorders (e.g., molybdenum cofactor deficiency, Smith-Lemli-Opitz syndrome, and adenylosuccinase deficiency), genetic syndromes (e.g., Ritscher-Schinzel, Joubert, and CHARGE syndromes), and brain malformations (primary posterior fossa malformations e.g., Dandy-Walker malformation, pontine tegmental cap dysplasia and rhombencephalosynapsis, or global brain malformations such as tubulinopathies and ?-dystroglycanopathies). Secondary (disruptive) conditions include prenatal infections (e.g., cytomegalovirus), exposure to teratogens, and extreme prematurity. The distinction between malformations and disruptions is important for pathogenesis and genetic counseling. Neuroimaging provides key information to categorize CH based on the pattern of involvement: unilateral CH, CH with mainly vermis involvement, global CH with involvement of both vermis and hemispheres, and pontocerebellar hypoplasia. The category of CH, associated neuroimaging findings and clinical features may suggest a specific disorder or help plan further investigations and interpret their results. Over the past decade, advances in neuroimaging and genetic testing have greatly improved clinical diagnosis, diagnostic testing, recurrence risk counseling, and information about prognosis for patients and their families. In the next decade, these advances will be translated into deeper understanding of these disorders and more specific treatments. PMID:24839100

Poretti, Andrea; Boltshauser, Eugen; Doherty, Dan

2014-06-01

201

Aprosencephaly and cerebellar dysgenesis in SIBS  

SciTech Connect

Aprosencephaly is a rare, lethal malformation sequence of the central nervous system that has been attributed to a postneuralation encephaloclastic process. We describe autopsy findings consistent with aprosencephaly in 2 fetuses conceived from a consanguineous mating (first cousins). Both showed anecephalic manifestations; however, the crania were intact, with fused sutures. The neuropathologic findings were essentially identical. Each fetus had complete absence of the telecephalon and pyramidal tracts, rudimentary diencephalic and mesencephalic structures, primitive cerebellar hemispheres, posterolateral clusters of primitive neural cells in the medullas suggesting an abnormality of neural migration, a normally-formed spinal cord, and retinal dysplasia within normally-formed globes. In addition, both fetuses manifested a peculiar perivascular mesenchymal proliferation seen only within the central nervous system. The similarity of these cases, coupled with parental consanguinity, suggests a primary malformation in brain development due to the homozygous representation of a mutant allele. We hypothesize that these patients may represent a defect in a gene important in brain development, the nature of which has yet to be elucidated. 26 refs., 4 figs., 4 tabs.

Florell, S.R.; Townsend, J.J.; Klatt, E.C. [Univ. of Utah Health Sciences Center, Salt Lake City, UT (United States)] [and others] [Univ. of Utah Health Sciences Center, Salt Lake City, UT (United States); and others

1996-06-28

202

Striatal influences on paravermal cerebellar activity.  

PubMed

Units were recorded extracellularly in paravermal cortex (lobule VI) of the cerebellum of chloralose anesthetized cats. Electrical stimulation of the striatum evoked excitation followed by inhibition in these neurons. In addition, the somatosensory properties of these cells were also affected by the striatum. A conditioning-test paradigm (C-T) was used in which conditioning stimulation was applied to the striatum. Test responses were evoked in cerebellar neurons by facial stimulation. As a function of the C-T interval, striatal stimulation could either enhance or suppress the test facial responses. In another procedure, a moveable electrode was used to map the thresholds for affecting the cerebellum from different points in the striatum. The lowest mean threshold was in the putamen followed respectively by the internal capsule and caudate nucleus. Control experiments suggested that striatal effects on the cerebellum were due neither to extra-striatal current spread nor antidromic activation of corticostriatal fibers. These data were discussed with regard to models of striatal motor functioning that indicate a role in postural control and sensory gating. PMID:3208861

Manetto, C; Lidsky, T I

1988-01-01

203

Mars Exploration Rover Terminal Descent Mission Modeling and Simulation  

NASA Technical Reports Server (NTRS)

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.

Raiszadeh, Behzad; Queen, Eric M.

2004-01-01

204

Thalamic, brainstem, and cerebellar glucose metabolism in the hemiplegic monkey  

SciTech Connect

Unilateral ablation of cerebral cortical areas 4 and 6 of Brodmann in the macaque monkey results in a contralateral hemiplegia that resolves partially with time. During the phase of dense hemiplegia, local cerebral metabolic rate for glucose (1CMRG1c) is decreased significantly in most of the thalamic nuclei ipsilateral to the ablation, and there are slight contralateral decreases. The lCMRGlc is reduced bilaterally in most of the brainstem nuclei and bilaterally in the deep cerebellar nuclei, but only in the contralateral cerebellar cortex. During the phase of partial motor recovery, lCMRGlc is incompletely restored in many of the thalamic nuclei ipsilateral to the ablation and completely restored in the contralateral nuclei. In the brainstem and deep cerebellar nuclei, poor to moderate recovery occurs bilaterally. Moderate recovery occurs in the contralateral cerebellar cortex. The findings demonstrate that a unilateral cerebral cortical lesion strongly affects lCMRGlc in the thalamus ipsilaterally and in the cerebellar cortex contralaterally, but in the brainstem bilaterally. Partial recovery of lCMRGlc accompanies the progressive motor recovery. The structures affected include those with direct, and also those with indirect, connections to the areas ablated.

Shimoyama, I.; Dauth, G.W.; Gilman, S.; Frey, K.A.; Penney, J.B. Jr.

1988-12-01

205

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

PubMed

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

Bolduc, Marie-Eve; Limperopoulos, Catherine

2009-04-01

206

Recurrent cerebellar architecture solves the motor-error problem.  

PubMed Central

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 structures to estimate unobservable motor error from its observed sensory consequences. We have proposed elsewhere a recurrent decorrelation control architecture in which Marr-Albus models learn without requiring motor error. Here, we prove convergence for this architecture and demonstrate important advantages for the modular control of systems with multiple degrees of freedom. These results are illustrated by modelling adaptive plant compensation for the three-dimensional vestibular ocular reflex. This provides a functional role for recurrent cerebellar connectivity, which may be a generic anatomical feature of projections between regions of cerebral and cerebellar cortex. PMID:15255096

Porrill, John; Dean, Paul; Stone, James V.

2004-01-01

207

Paraneoplastic cerebellar degeneration associated with serous adenocarcinoma of the ovary.  

PubMed

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

Saeed, Duaa B; Gupta, Limci

2014-01-01

208

Cerebellar activity and disturbed time sense after THC.  

PubMed

Because marijuana continues to be the most commonly used illicit drug, its effects on the brain function are of major interest. We utilized positron emission tomography (PET) and magnetic resonance imaging (MRI) to study the effects of delta-9-tetrahydrocannabinol (THC) infusion on brain blood flow and its behavioral correlates in 46 volunteers. Consistent with previous reports, there was a significant increase in cortical and cerebellar blood flow following THC, but not all subjects showed this effect. Those who showed a decrease in cerebellar CBF also had a significant alteration in time sense. The relationship between decreased cerebellar flow and impaired time sense is of interest because the cerebellum has been linked to an internal timing system. PMID:9666122

Mathew, R J; Wilson, W H; Turkington, T G; Coleman, R E

1998-06-29

209

Cerebellar Hypoplasia, Continuous Spike-waves During Sleep, and Neuropsychological and Behavioral Disorders  

Microsoft Academic Search

We describe 3 patients with different degrees of cerebellar hypoplasia and continuous spike-waves during sleep: the more extensive the cerebellar hypoplasia, the more compromised the neuropsychological abilities and behavior. Cerebellar hypoplasia is a risk factor for epilepsy and\\/or neuropsychological and psychiatric disorders. Epilepsy is also strongly associated with familial antecedents for seizures, as previously reported. The cerebellum is implicated in

Antonia Parmeggiani; Annio Posar; Maria Cristina Scaduto

2008-01-01

210

Recurrent Cerebellar Loops Simplify Adaptive Control of Redundant and Nonlinear Motor Systems  

Microsoft Academic Search

We have described elsewhere an adaptivefilter model of cerebellar learn- ing in which the cerebellar microcircuit acts to decorrelate motor com- mands from their sensory consequences (Dean, Porrill, & Stone, 2002). Learning stability required the cerebellar microcircuit to be embedded in a recurrent loop, and this has been shown to lead to a simple and modular adaptive control architecture when

John Porrill; Paul Dean

2007-01-01

211

International Cooperative Ataxia Rating Scale for pharmacological assessment of the cerebellar syndrome  

Microsoft Academic Search

Despite the involvement of cerebellar ataxia in a large variety of conditions and its frequent association with other neurological symptoms, the quantification of the specific core of the cerebellar syndrome is possible and useful in Neurology. Recent studies have shown that cerebellar ataxia might be sensitive to various types of pharmacological agents, but the scales used for assessment were all

P. Trouillas; T. Takayanagi; M. Hallett; R. D. Currier; S. H. Subramony; K. Wessel; A. Bryer; H. C. Diener; S. Massaquoi; C. M. Gomez; P. Coutinho; M. Ben Hamida; G. Campanella; A. Filla; L. Schut; D. Timann; J. Honnorat; N. Nighoghossian; B. Manyam

1997-01-01

212

Incidence of dysarthria in children with cerebellar tumors: A prospective study  

Microsoft Academic Search

The present study investigated dysarthric symptoms in children with cerebellar tumors. Ten children with cerebellar tumors and 10 orthopedic control children were tested prior and one week after surgery. Clinical dysarthric symptoms were quantified in spontaneous speech. Syllable durations were analyzed in syllable repetition and sentence production tasks. Localization of the cerebellar lesions were defined after manual transfer from individual

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

2005-01-01

213

Cerebellar learning of accurate predictive control for fast-reaching movements  

Microsoft Academic Search

Long conduction delays in the nervous system prevent the accurate control of movements by feedback control alone. We present a new, biologically plausible cerebellar model to study how fast arm movements can be executed in spite of these delays. To provide a realistic test-bed of the cerebellar neural model, we embed the cerebellar network in a simulated biological motor system

Jacob Spoelstra; Nicolas Schweighofer; Michael A. Arbib

2000-01-01

214

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

NASA Technical Reports Server (NTRS)

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.

1989-01-01

215

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

Microsoft Academic Search

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,

E S Kiff; P R Barnes; M Swash

1984-01-01

216

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

E-print Network

an air-bag system or a powered-descent system (throttleable rockets that descend the lander). Landing with onboard guidance algo- rithms. Current guidance methods ensure a safe landing that avoids impact- efficient algorithms. The descent thrusters typically cannot Authors are with the Jet Propulsion Laboratory

Williams, Brian C.

217

Classifying Facial Expression with Radial Basis Function Netowrks, using Gradient Descent and K-means  

Microsoft Academic Search

This paper compares methods of training radial basis function networks. We found RBF networks initialized by supervised clustering perform bet- ter than networks initialized by unsupervised clustering and improved with gradient descent. Gradient descent did not significantly improve the networks initialized by supervised clustering.

Neil Alldrin; Andrew Smith; Doug Turnbull

218

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

219

Mitral annular descent velocity by tissue Doppler echocardiography as an index of global left ventricular function  

Microsoft Academic Search

Mitral annular descent has been described as an index of left ventricular (LV) systolic function, which is independent of endocardial definition. Echocardiographic tissue Doppler imaging is a new technique that calculates and displays color-coded cardiac tissue velocities on-line. To evaluate mitral annular descent velocity as a rapid index of global LV function, we performed tissue Doppler imaging studies in 55

Vijay K. Gulati; William E. Katz; William P. Follansbee; John Gorcsan

1996-01-01

220

Descent of the hyoid in chimpanzees: evolution of face flattening and speech  

Microsoft Academic Search

The human supralaryngeal vocal tract develops to form a unique two-tube configuration with equally long horizontal and vertical cavities. This anatomy contributes greatly to the morphological foundations of human speech. It is believed to depend on the reduced growth of the palate and on the developmental descent of the larynx relative to the palate. Anatomically, the descent of the larynx

Takeshi Nishimura; Akichika Mikami; Juri Suzuki; Tetsuro Matsuzawa

2006-01-01

221

Evaluation of vertical profiles to design continuous descent approach procedure  

NASA Astrophysics Data System (ADS)

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.

Pradeep, Priyank

222

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

PubMed

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

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

2014-06-01

223

Sudden Onset of Oromandibular Dystonia after Cerebellar Stroke  

PubMed Central

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

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

2014-01-01

224

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

NASA Astrophysics Data System (ADS)

A new generation of inflatable Entry, Descent and Landing System (EDLS) for Mars has been developed. It is used in both the initial atmospheric entry and atmospheric descent before the semi-hard impact of the penetrator into Martian surface. The EDLS applicability to Earth's atmosphere is studied by the EU/RITD [1] project. Project focuses to the analysis and tests of the transonic behaviour of this compact and light weight payload entry system at the Earth re-entry. 1. EDLS for Earth The dynamical stability of the craft is analysed, concentrating on the most critical part of the atmospheric re-entry, the transonic phase. In Martian atmosphere the MetNet vehicle stability during the transonic phase is understood. However, in the more dense Earth's atmosphere, the transonic phase is shorter and turbulence more violent. Therefore, the EDLS has to be sufficiently dynamically stable to overcome the forces tending to deflect the craft from its nominal trajectory and attitude. The preliminary design of the inflatable EDLS for Earth will be commenced once the scaling of the re-entry system and the dynamical stability analysis have been performed. The RITD-project concentrates on mission and applications achievable with the current MetNet-type (i.e. 'Mini-1' category) of lander, and on requirements posed by other type Earth re-entry concepts. 2. Entry Angle Determination for Mini-1 - lander For successful Earth landing, the suitable re-entry angle and velocity with specific descent vehicle (DV) mass and heat flux parameters need to be determined. These key parameters in determining the Earth re-entry for DV are: qmax (kW/m2): maximal specific heat flux, Q (MJ/m2): specific integral heat flux to DV front shield, m (kg): descent vehicle (DV) mass, V (m/s): re-entry velocity and ? (deg.): flight-path angle at Earth re-entry For Earth re-entry, the calculation results in the optimal value of entry velocity for MetNet ('Mini-1' category) -type lander, with mass of 22kg, being VSOL = 5268 m/s. Using the basic pre-defined parameters for MetNet-type of lander in Earth atmosphere, we get the optimal angle of ? = -3.06 degrees for Earth re-entry. 3. Payload Mass for Earth Entry DV One of the key elements in Earth entry lander is the amount of available payload mass. The payload mass depends on, e.g., the lander size, landing type (soil or water), heat shield durability and additional landing gear. The payload mass will have an impact to the center of gravity of the lander. The payload with a 'low' CoG (compared the the lander structure) has a larger tolerance than the payload with 'high' CoG. In cases where payload CoG causes instability, the extra balance mass can be used to adjust CoG. This balance mass will reduce the available payload mass. A major limitation for payload mass is the heat shielding. Acknowledgements The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 263255. References [1] http://ritd.fmi.fi

Heilimo, Jyri; Harri, Ari-Matti; Aleksashkin, Sergey; Koryanov, Vsevolod; Arruego, Ignacio; Schmidt, Walter; Haukka, Harri; Finchenko, Valery; Martynov, Maxim; Ostresko, Boris; Ponomarenko, Andrey; Kazakovtsev, Viktor; Martin, Susanna; Siili, Tero

2014-05-01

225

Overview of the Phoenix Entry, Descent and Landing System Architecture  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

226

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

NASA Astrophysics Data System (ADS)

Abstract A new generation of in?atable Entry, Descent and Landing System (EDLS) or Mars has been developed. It is used in both the initial atmospheric entry and atmospheric descent before the semi-hard impact of the penetrator into Martian surface. The EDLS applicability to Earth’s atmosphere is studied by the EU/RITD [1] project. Project focuses to the analysis and tests of the transonic behaviour of this compact and light weight payload entry system at the Earth re-entry 1. EDLS for Earth The dynamical stability of the craft is analysed, concentrating on the most critical part of the atmospheric re-entry, the transonic phase. In Martian atmosphere the MetNet vehicle stability during the transonic phase is understood. However, in the more dense Earth’s atmosphere, the transonic phase is shorter and turbulence more violent. Therefore, the EDLS has to be sufficiently dynamically stable to overcome the forces tending to deflect the craft from its nominal trajectory and attitude. The preliminary design of the inflatable EDLS for Earth will be commenced once the scaling of the re-entry system and the dynamical stability analysis have been performed. The RITD-project concentrates on mission and applications achievable with the current MetNet-type (i.e. “Mini-1” category) of lander, and on requirements posed by other type Earth re-entry concepts. 2. Entry Angle Determination for Mini-1 - lander For successful Earth landing, the suitable re-entry angle and velocity with specific descent vehicle (DV) mass and heat flux parameters need to be determined. These key parameters in determining the Earth re-entry for DV are: - qmax (kW/m2): maximal specific heat flux, - Q (MJ/m2): specific integral heat flux to DV front shield, - m (kg): descent vehicle (DV) mass, - V (m/s): re-entry velocity and - theta(deg.): flight-path angle at Earth re-entry For Earth re-entry, the calculation results in the optimal value of entry velocity for MetNet (“Mini-1” category) -type lander, with mass of 22kg, being VSOL = 5268 m/s. Using the basic pre-defined parameters for MetNet-type of lander in Earth atmosphere, we get the optimal angle of = -3.06 degrees for Earth re-entry. 3. Payload Mass for Earth Entry DV One of the key elements in Earth entry lander is the amount of available payload mass. The payload mass depends on, e.g., the lander size, landing type (soil or water), heat shield durability and additional landing gear. The payload mass will have an impact to the center of gravity of the lander. The payload with a “low” CoG (compared the the lander structure) has a larger tolerance than the payload with “high” CoG. In cases where payload CoG causes instability, the extra balance mass can be used to adjust CoG. This balance mass will reduce the available payload mass. A major limitation for payload mass is the heat shielding. Acknowledgements The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 263255. References [1] http://ritd.fmi.fi

Heilimo, Jyri; Aleksashkin, Sergey; Martynov, Maxim; Schmidt, Walter; Harri, Ari-Matti; Vsevolod Koryanov, D.; Kazakovtcev, Victor; Haukka, Harri; Arruego, Ignacio; Finchenko, Valery; Ostresko, Boris; Ponomarenko, Andrei; Martin, Susanna; Siili, Tero

227

Gradient descent learning in and out of equilibrium  

SciTech Connect

Relations between the off thermal equilibrium dynamical process of on-line learning and the thermally equilibrated off-line learning are studied for potential gradient descent learning. The approach of Opper to study on-line Bayesian algorithms is used for potential based or maximum likelihood learning. We look at the on-line learning algorithm that best approximates the off-line algorithm in the sense of least Kullback-Leibler information loss. The closest on-line algorithm works by updating the weights along the gradient of an effective potential, which is different from the parent off-line potential. A few examples are analyzed and the origin of the potential annealing is discussed.

Caticha, Nestor; Araujo de Oliveira, Evaldo

2001-06-01

228

Scientific basis of testicular descent and management implications for cryptorchidism.  

PubMed

Cryptorchidism occurs in about 1% of boys, but has a raised incidence in those with deficiencies of androgen function. Greater knowledge of fetal-maternal endocrinology and related experimental work has provided evidence that fetal testicular endocrine function is vital in descent of the gonad. The therapeutic use of hCG has, however, been disappointing, and its role is confined to helping to distinguish the retractile from the undescended testis. Cryptorchidism is commonly associated with congenital pathological defects such as ductal abnormalities, and others (including interstitial fibrosis and a reduction in germ cells) develop after 1-2 years, while later these patients are at greater risk of carcinoma in situ and germ cell cancer. The demonstration of the early pathological changes has recently dictated much earlier surgical correction, but long-term follow-up is needed to prove clinical benefit from this practice. PMID:7910032

Kiely, E A

1994-01-01

229

Mars Science Laboratory Entry, Descent, and Landing System Overview  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

230

Mars Exploration Rovers Entry, Descent, and Landing Trajectory Analysis  

NASA Technical Reports Server (NTRS)

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.

Desai, Prasun N.; Knocke, Philip C.

2004-01-01

231

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

232

Trigeminal neuralgia caused by nerve compression by dilated superior cerebellar artery associated with cerebellar arteriovenous malformation: case report.  

PubMed

Intracranial arteriovenous malformation (AVM) is a rare cause of trigeminal neuralgia (TGN). In this presented case, successful resolution of AVM-related TGN following embolization and gamma knife stereotactic radiosurgery (GKRS) was obtained. A patient suffered from TGN on the left side, which was thought to be caused by root entry zone compression by dilated superior cerebellar artery (SCA) associated with cerebellar AVM. The cerebellar vermis AVM was embolized in endovascular surgery. The AVM was reduced in size and TGN was partially relieved. The patient subsequently underwent GKRS for the residual nidus. TGN was completely resolved within one year and a half. GKRS following embolization of the nidus improved the flow-related dilation of the SCA and completely relieved TGN. PMID:24257486

Mori, Yoshimasa; Kobayashi, Tatsuya; Miyachi, Shigeru; Hashizume, Chisa; Tsugawa, Takahiko; Shibamoto, Yuta

2014-01-01

233

Tumour type and size are high risk factors for the syndrome of “cerebellar” mutism and subsequent dysarthria  

Microsoft Academic Search

OBJECTIVE“Cerebellar mutis” and subsequent dysarthria (MSD) is a documented complication of posterior fossa surgery in children. In this prospective study the following risk factors for MSD were assessed: type, size and site of the tumour; hydrocephalus at presentation and after surgery, cerebellar incision site, postoperative infection, and cerebellar swelling.METHODSIn a consecutive series of 42 children with a cerebellar tumour, speech

Coriene E Catsman-Berrevoets; Hugo R Van Dongen; Paul G H Mulder; Daniel Paz y Geuze; Philippe F Paquier; Maarten H Lequin

1999-01-01

234

Late effects of radiotherapy on patients with cerebellar medulloblastoma  

Microsoft Academic Search

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

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

1984-01-01

235

Cerebellar Morphology in Tourette Syndrome and Obsessive-Compulsive  

E-print Network

Cerebellar Morphology in Tourette Syndrome and Obsessive-Compulsive Disorder Russell H. Tobe, MD morphology and under- lying volumes for the main diagnosis effects of TS as well as comorbid obsessive-compulsive and attenuates during adolescence. TS is 3­4 more com- mon in males.1,2 Obsessive-compulsive disorder (OCD

236

A New Functional Role for Cerebellar Long Term Depression  

E-print Network

A New Functional Role for Cerebellar Long Term Depression PROGRESS IN BRAIN RESEARCH 114: 529 of Antwerp - UIA, B2610 Antwerp, Belgium Abstract Long-term depression (LTD) of excitatory synaptic-Albus-Ito theories (Schreurs and Alkon, 1993). I will first review and criticize the Marr-Albus-Ito theories

De Schutter, Erik

237

Basal ganglia and cerebellar loops: motor and cognitive circuits  

Microsoft Academic Search

The traditional view that the basal ganglia and cerebellum are simply involved in the control of movement has been challenged in recent years. One of the pivotal reasons for this reappraisal has been new information about basal ganglia and cerebellar connections with the cerebral cortex. In essence, recent anatomical studies have revealed that these connections are organized into discrete circuits

Frank A Middleton; Peter L Strick

2000-01-01

238

Predicting and correcting ataxia using a model of cerebellar function.  

PubMed

Cerebellar damage results in uncoordinated, variable and dysmetric movements known as ataxia. Here we show that we can reliably model single-joint reaching trajectories of patients (n = 10), reproduce patient-like deficits in the behaviour of controls (n = 11), and apply patient-specific compensations that improve reaching accuracy (P < 0.02). Our approach was motivated by the theory that the cerebellum is essential for updating and/or storing an internal dynamic model that relates motor commands to changes in body state (e.g. arm position and velocity). We hypothesized that cerebellar damage causes a mismatch between the brain's modelled dynamics and the actual body dynamics, resulting in ataxia. We used both behavioural and computational approaches to demonstrate that specific cerebellar patient deficits result from biased internal models. Our results strongly support the idea that an intact cerebellum is critical for maintaining accurate internal models of dynamics. Importantly, we demonstrate how subject-specific compensation can improve movement in cerebellar patients, who are notoriously unresponsive to treatment. PMID:24812203

Bhanpuri, Nasir H; Okamura, Allison M; Bastian, Amy J

2014-07-01

239

Speech and Language Findings Associated with Paraneoplastic Cerebellar Degeneration  

ERIC Educational Resources Information Center

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…

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

2005-01-01

240

Verb Generation in Children and Adolescents with Acute Cerebellar Lesions  

ERIC Educational Resources Information Center

The aim of the present study was to examine verb generation in a larger group of children and adolescents with acute focal lesions of the cerebellum. Nine children and adolescents with cerebellar tumours participated. Subjects were tested a few days after tumour surgery. For comparison, a subgroup was tested also 1 or 2 days before surgery. None…

Frank, B.; Schoch, B.; Hein-Kropp, C.; Dimitrova, A.; Hovel, M.; Ziegler, W.; Gizewski, E. R.; Timmann, D.

2007-01-01

241

The myelination of the cerebellar cortex in the cat  

Microsoft Academic Search

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

W. Lange; Hochschule Aachen

1978-01-01

242

Skull malformation and cerebellar herniation in captive African lions  

Microsoft Academic Search

Thickening of the cranial vault with a resulting cerebellar herniation is described in a series of litters of lion cubs, all with the same parents, one of whom was also very mildly affected. This animal, when mated to his daughter, also produced affected cubs. The aetiology of the condition is discussed and it is considered that vitamin A deficiency may

JR Baker; DG Lyon

1977-01-01

243

Mechanisms of synchronous activity in cerebellar Purkinje cells  

PubMed Central

Complex spike synchrony is thought to be a key feature of how inferior olive climbing fibre afferents make their vital contribution to cerebellar function. However, little is known about whether the other major cerebellar input, the mossy fibres (which generate simple spikes within Purkinje cells, PCs), exhibit a similar synchrony in impulse timing. We have used a multi-microelectrode system to record simultaneously from two or more PCs in the posterior lobe of the ketamine/xylazine-anaesthetized rat to examine the relationship between complex spike and simple spike synchrony in PC pairs located mainly in the A2 and C1 zones in crus II and the paramedian lobule. PC pairs displaying correlations in the occurrence of their complex spikes (coupled PCs) were usually located in the same zone and were also more likely to exhibit correlations in the timing of their spontaneous simple spikes and associated pauses in activity. In coupled PCs, synchrony in both complex spike and simple spike activity was enhanced and the relative timing in the occurrence of complex spikes could be altered by peripheral stimulation. We conclude that the functional coupling between PC pairs in their complex spike and simple spike activity can be significantly modified by sensory inputs, and that mechanisms besides electrotonic coupling are involved in generating PC synchrony. Synchronous activity in multiple PCs converging onto the same cerebellar nuclear cells is likely to have a significant impact on cerebellar output that could form important timing signals to orchestrate coordinated movements. PMID:20442262

Wise, Andrew K; Cerminara, Nadia L; Marple-Horvat, Dilwyn E; Apps, Richard

2010-01-01

244

Cerebellar Involvement in Response Reassignment Rather Than Attention  

E-print Network

studies suggest the cerebellum is involved in switching attentional set. We present evidence that fails by infantile autism or neurological damage (Ak- shoomoff and Courchesne, 1992), Courchesne et al. (1994) ob dimensions. Imaging data in normal subjects revealed enhanced activity in lateral cerebellar cortex when

Ivry, Rich

245

Translational Approach to Behavioral Learning: Lessons from Cerebellar Plasticity  

PubMed Central

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

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

2013-01-01

246

Eyeblink Conditioning Deficits Indicate Timing and Cerebellar Abnormalities in Schizophrenia  

ERIC Educational Resources Information Center

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

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

247

Manual and Semiautomated Measurement of Cerebellar Subregions on MR Images  

Microsoft Academic Search

Previous structural and functional imaging studies suggest that the corticocerebellar–thalamic–cortical circuit is dysfunctional in schizophrenia. Accurate identification and volumetric measurement of cerebellar subregions are essential to the assessment of the cerebellum's role in healthy and disease states. Manual parcellation of the cerebellum on MR images was performed with the use of guide traces. Guide traces identified relevant fissures and borders

Ronald Pierson; Patricia Westmoreland Corson; Lonnie L. Sears; Daniel Alicata; Vincent Magnotta; Daniel O'Leary; Nancy C. Andreasen

2002-01-01

248

Recurrent cerebellar architecture solves the motor-error problem  

Microsoft Academic Search

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

John Porrill; Paul Dean; James V. Stone

2004-01-01

249

Ascending Granule Cell Axon: An Important Component of Cerebellar  

E-print Network

GUNDAPPA-SULUR,1 ERIK DE SCHUTTER,2 AND JAMES M. BOWER3* 1Department of Pathology, University of California. 1999 Wiley-Liss, Inc. Indexing terms: cerebellum; Purkinje cells; synapses; electron microscopy influence on theories and models of cerebellar function (Eccles et al., 1967; Marr, 1969; Albus, 1971

De Schutter, Erik

250

Cerebellar Purkinje cell p75 neurotrophin receptor and autistic behavior.  

PubMed

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

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

2014-01-01

251

Cerebellar inhibition of inferior olivary transmission in the decerebrate ferret.  

PubMed

Stimulation around the superior cerebellar peduncle or within the deep cerebellar nuclei is known to inhibit the inferior olive with a very long latency. It has been suggested that this inhibition is mediated by the GABA-ergic nucleo-olivary pathway, but alternative explanations such as activation of an indirect excitatory pathway or a pathway via the red nucleus are possible. A long-latency inhibition via the nucleo-olivary pathway would have profound implications for cerebellar function and the present study was performed to test alternative explanations and to characterize the nucleo-olivary inhibition. Climbing fibre responses (CFRs), evoked by periorbital stimulation and recorded from the cerebellar cortex, could be inhibited by stimulation of two distinct mesencephalic areas. One was located within the superior cerebellar peduncle and the other about 1 mm further ventrally. Inhibition evoked from either area occurred in the inferior olive and was independent of a red nucleus relay. Single Purkinje cell recordings revealed that inhibition from the ventral area was not secondary to olivary activation. It is concluded that stimulation of the ventral area activated nucleo-olivary fibres. The inhibition elicited by stimulation within the peduncle probably resulted from indirect activation on the nucleo-olivary fibres via antidromic activation of the interpositus nucleus. The time courses of the inhibition from the two areas were indistinguishable. The duration of the strongest inhibition was short and had a sharp peak at about 30 ms. It is suggested that the time course of the inhibition is important for temporal regulation of learned responses. PMID:16132968

Svensson, P; Bengtsson, F; Hesslow, G

2006-01-01

252

Physiological and morphological development of the rat cerebellar Purkinje cell.  

PubMed

Cerebellar Purkinje cells integrate multimodal afferent inputs and, as the only projection neurones of the cerebellar cortex, are key to the coordination of a variety of motor- and learning-related behaviours. In the neonatal rat the cerebellum is undeveloped, but over the first few postnatal weeks both the structure of the cerebellum and cerebellar-dependent behaviours mature rapidly. Maturation of Purkinje cell physiology is expected to contribute significantly to the development of cerebellar output. However, the ontogeny of the electrophysiological properties of the Purkinje cell and its relationship to maturation of cell morphology is incompletely understood. To address this problem we performed a detailed in vitro electrophysiological analysis of the spontaneous and intracellularly evoked intrinsic properties of Purkinje cells obtained from postnatal rats (P0 to P90) using whole-cell patch clamp recordings. Cells were filled with neurobiotin to enable subsequent morphological comparisons. Three stages of physiological and structural development were identified. During the early postnatal period (P0 to approximately P9) Purkinje cells were characterized by an immature pattern of Na(+)-spike discharge, and possessed only short multipolar dendrites. This was followed by a period of rapid maturation (from approximately P12 to approximately P18), consisting of changes in Na(+)-spike discharge, emergence of repetitive bursts of Na(+) spikes terminated by Ca(2+) spikes (Ca(2+)-Na(+) bursts), generation of the trimodal pattern, and a significant expansion of the dendritic tree. During the final stage (> P18 to P90) there were minor refinements of cell output and a plateau in dendritic area. Our results reveal a rapid transition of the Purkinje cell from morphological and physiological immaturity to adult characteristics over a short developmental window, with a close correspondence between changes in cell output and dendritic growth. The development of Purkinje cell intrinsic electrophysiological properties further matches the time course of other measures of cerebellar structural and functional maturation. PMID:16002452

McKay, Bruce E; Turner, Ray W

2005-09-15

253

Adaptive robotic control driven by a versatile spiking cerebellar network.  

PubMed

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

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

2014-01-01

254

Neuroimaging Evidence of Cerebellar Involvement in Premenstrual Dysphoric Disorder  

PubMed Central

Background Premenstrual dysphoric disorder (PMDD) is a debilitating cyclic disorder that is characterized by affective symptoms, including irritability, depression, and anxiety which arise in the luteal phase of the menstrual cycle and resolve soon after the onset of menses. Despite a prevalence of up to 8% in women of reproductive age, few studies have investigated the brain mechanisms that underlie this disorder. Methods We used positron emission tomography with [18F] fluorodeoxyglucose and self-report questionnaires to assess cerebral glucose metabolism and mood in 12 women with PMDD and 12 healthy comparison subjects in the follicular and late luteal phases of the menstrual cycle. The primary biological endpoint was incorporated regional cerebral radioactivity (scaled to the global mean) as an index of glucose metabolism. Relationships between regional brain activity and mood ratings were assessed. Blood samples were taken before each session for assay of plasma estradiol and progesterone concentrations. Results There were no group differences in hormone levels in either the follicular or late luteal phase, but the groups differed in the effect of menstrual phase on cerebellar activity. Women with PMDD, but not comparison subjects, showed an increase in cerebellar activity (particularly in the right cerebellar vermis) from the follicular phase to the late luteal phase (p = 0.003). In the PMDD group, this increase in cerebellar activity was correlated with worsening of mood (p = 0.018). Conclusions These findings suggest that the midline cerebellar nuclei, which have been implicated in other mood disorders, also contribute to negative mood in PMDD. PMID:21092938

Rapkin, Andrea J.; Berman, Steven M.; Mandelkern, Mark A.; Silverman, Daniel H. S.; Morgan, Melinda; London, Edythe D.

2010-01-01

255

Adaptive Robotic Control Driven by a Versatile Spiking Cerebellar Network  

PubMed Central

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

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

2014-01-01

256

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

PubMed Central

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

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

2013-01-01

257

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

PubMed Central

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

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

2013-01-01

258

Preliminary Study of a Model Rotor in Descent  

NASA Technical Reports Server (NTRS)

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.

McAlister, K. W.; Tung, C.; Sharpe, D. L.; Huang, S.; Hendley, E. M.

2000-01-01

259

Engineering description of the ascent/descent bet product  

NASA Technical Reports Server (NTRS)

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.

Seacord, A. W., II

1986-01-01

260

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

NASA Technical Reports Server (NTRS)

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.

Murray, James E.; Tartabini, Paul V.

2001-01-01

261

Cortical network functional connectivity in the descent to sleep.  

PubMed

Descent into sleep is accompanied by disengagement of the conscious brain from the external world. It follows that this process should be associated with reduced neural activity in regions of the brain known to mediate interaction with the environment. We examined blood oxygen dependent (BOLD) signal functional connectivity using conventional seed-based analyses in 3 primary sensory and 3 association networks as normal young adults transitioned from wakefulness to light sleep while lying immobile in the bore of a magnetic resonance imaging scanner. Functional connectivity was maintained in each network throughout all examined states of arousal. Indeed, correlations within the dorsal attention network modestly but significantly increased during light sleep compared to wakefulness. Moreover, our data suggest that neuronally mediated BOLD signal variance generally increases in light sleep. These results do not support the view that ongoing BOLD fluctuations primarily reflect unconstrained cognition. Rather, accumulating evidence supports the hypothesis that spontaneous BOLD fluctuations reflect processes that maintain the integrity of functional systems in the brain. PMID:19255447

Larson-Prior, Linda J; Zempel, John M; Nolan, Tracy S; Prior, Fred W; Snyder, Abraham Z; Raichle, Marcus E

2009-03-17

262

Mars Science Laboratory Entry, Descent, and Landing System Overview  

NASA Technical Reports Server (NTRS)

In 2012, the Mars Science Laboratory (MSL) mission will pioneer the next generation of robotic Entry, Descent, and Landing (EDL) systems by delivering the largest and most capable rover to date to the surface of Mars. In addition to landing more mass than prior missions to Mars, MSL will offer access to regions of Mars that have been previously unreachable. The MSL EDL sequence is a result of a more stringent requirement set than any of its predecessors. Notable among these requirements is landing a 900 kg rover in a landing ellipse much smaller than that of any previous Mars lander. In meeting these requirements, MSL is extending the limits of the EDL technologies qualified by the Mars Viking, Mars Pathfinder, and Mars Exploration Rover missions. Thus, there are many design challenges that must be solved for the mission to be successful. Several pieces of the EDL design are technological firsts, such as guided entry and precision landing on another planet, as well as the entire Sky Crane maneuver. This paper discusses the MSL EDL architecture and discusses some of the challenges faced in delivering an unprecedented rover payload to the surface of Mars.

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

2010-01-01

263

Direct Temperature Measurements during Netlander Descent on Mars  

NASA Astrophysics Data System (ADS)

A new design for a platinum thermoresistance temperature sensor has been developed and tested in Earth's atmosphere and stratosphere. It will be one of the sensors equipping the scientific package ATMIS (Atmospheric and Meteorology Instrument System), which will be devoted to the measurement of the meteorological parameters during both the entry/descent phase and the surface phase, aboard the Netlanders. In particular vertical profiles of temperature, density and pressure will allow the resolution of vertical gradients to investigate the atmospheric structure and dynamics. In view of the future missions to Mars, Netlander represents a unique chance to increase significantly the climate record both in time and in space, doubling the current knowledge of the atmospheric parameters. Furthermore is the only opportunity to conduct direct measurement of temperature and pressure (outside the boundary layer of the airbags used for the landing). The temperature sensor proposed is a platinum thermoresistance, enhancement of HASI TEM (Cassini/Huygens Mission); a substantial improvement of the performances, i.e. a faster dynamic response, has been obtained. Two different prototypes of new design sensor have been built, laboratory test are proceeding and the second one has been already flown aboard a stratospheric balloon.

Colombatti, G.; Angrilli, F.; Ferri, F.; Francesconi, A.; Fulchignoni, M.; Lion Stoppato, P. F.; Saggi, B.

1999-09-01

264

Physics-based Entry, Descent and Landing Risk Model  

NASA Technical Reports Server (NTRS)

A physics-based risk model was developed to assess the risk associated with thermal protection system failures during the entry, descent and landing phase of a manned spacecraft mission. In the model, entry trajectories were computed using a three-degree-of-freedom trajectory tool, the aerothermodynamic heating environment was computed using an engineering-level computational tool and the thermal response of the TPS material was modeled using a one-dimensional thermal response tool. The model was capable of modeling the effect of micrometeoroid and orbital debris impact damage on the TPS thermal response. A Monte Carlo analysis was used to determine the effects of uncertainties in the vehicle state at Entry Interface, aerothermodynamic heating and material properties on the performance of the TPS design. The failure criterion was set as a temperature limit at the bondline between the TPS and the underlying structure. Both direct computation and response surface approaches were used to compute the risk. The model was applied to a generic manned space capsule design. The effect of material property uncertainty and MMOD damage on risk of failure were analyzed. A comparison of the direct computation and response surface approach was undertaken.

Gee, Ken; Huynh, Loc C.; Manning, Ted

2014-01-01

265

Evolution and ecology of directed aerial descent in arboreal ants.  

PubMed

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

Yanoviak, Stephen P; Munk, Yonatan; Dudley, Robert

2011-12-01

266

HLA Type Inference via Haplotypes Identical by Descent  

NASA Astrophysics Data System (ADS)

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.

Setty, Manu N.; Gusev, Alexander; Pe'Er, Itsik

267

User's manual for a fuel-conservative descent planning algorithm implemented on a small programmable calculator  

NASA Technical Reports Server (NTRS)

A simplified flight management descent algorithm was developed and programmed on a small programmable calculator. It was designed to aid the pilot in planning and executing a fuel conservative descent to arrive at a metering fix at a time designated by the air traffic control system. The algorithm may also be used for planning fuel conservative descents when time is not a consideration. The descent path was calculated for a constant Mach/airspeed schedule from linear approximations of airplane performance with considerations given for gross weight, wind, and nonstandard temperature effects. An explanation and examples of how the algorithm is used, as well as a detailed flow chart and listing of the algorithm are contained.

Vicroy, D. D.

1984-01-01

268

A taxonomy of descent algorithms for nonlinear programs and variational inequalities  

E-print Network

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

Patriksson, Michael

269

Entry, Descent and Landing (EDL) Technology Investments Within NASA's Space Technology Mission Directorate (STMD)  

NASA Astrophysics Data System (ADS)

NASA’s Space Technology Mission Directorate has several investments in entry, descent and landing technologies, across its nine programs. This presentation will give a top-level view of the various investments.

Munk, M. M.

2014-06-01

270

Atmospheric Properties Reconstruction from the Mars Science Laboratory Entry, Descent and Landing  

NASA Astrophysics Data System (ADS)

Data acquired during the entry, descent and landing of the Mars Science Laboratory were used to reconstruct the atmospheric profiles for density, pressure and temperature with excellent vertical resolution and extent.

Holstein-Rathlou, C.; Withers, P.

2014-07-01

271

A conflict analysis of 4D descent strategies in a metered, multiple-arrival route environment  

NASA Technical Reports Server (NTRS)

A conflict analysis was performed on multiple arrival traffic at a typical metered airport. The Flow Management Evaluation Model (FMEM) was used to simulate arrival operations using Denver Stapleton's arrival route structure. Sensitivities of conflict performance to three different 4-D descent strategies (clear-idle Mach/Constant AirSpeed (CAS), constant descent angle Mach/CAS and energy optimal) were examined for three traffic mixes represented by those found at Denver Stapleton, John F. Kennedy and typical en route metering (ERM) airports. The Monte Carlo technique was used to generate simulation entry point times. Analysis results indicate that the clean-idle descent strategy offers the best compromise in overall performance. Performance measures primarily include susceptibility to conflict and conflict severity. Fuel usage performance is extrapolated from previous descent strategy studies.

Izumi, K. H.; Harris, C. S.

1990-01-01

272

Vision-Aided Inertial Navigation for Spacecraft Entry, Descent, and Landing  

Microsoft Academic Search

In this paper, we present the vision-aided inertial navigation (VISINAV) algorithm that enables precision planetary landing. The vision front-end of the VISINAV system extracts 2-D-to-3-D correspondences between descent images and a surface map (mapped landmarks), as well as 2-D-to-2-D feature tracks through a sequence of descent images (opportunistic features). An extended Kalman filter (EKF) tightly integrates both types of visual

Anastasios I. Mourikis; Nikolas Trawny; Stergios I. Roumeliotis; Andrew Edie Johnson; Adnan Ansar; Larry Matthies

2009-01-01

273

Analysis of Flight Management System Predictions of Idle-Thrust Descents  

NASA Technical Reports Server (NTRS)

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.

Stell, Laurel

2010-01-01

274

Ovarian cancer revealed by paraneoplastic cerebellar degeneration: a case report  

PubMed Central

The prevalence of paraneoplastic cerebellar degeneration (PCD) associated with gynecological cancer is rare. Here, we reported the first case of ovarian cancer revealed by PCD in our institute. we describe a 80- year –old Moroccan female presented with subacute vestibular and cerebellar syndromes, she had an inguinal lymphadenopathy,with high levels of Anti-YO. Rapid progression and absence of known etiologies point towards a probable paraneoplastic origin of the syndrome in this patient. The exact incidence of PNS among those diagnosed with cancer remains uncertain, it is important to report this cases in the literature to help early diagnosis and appropriate treatment, which are able to stabilize the neurological symptoms. PMID:25360186

Elomrani, Fadwa; Ouziane, Imane; Boutayeb, Saber; Bensouda, Youssef; Mrabti, Hind; Errihani, Hassan

2014-01-01

275

Cerebellar Cognitive Affective Syndrome Presented as Severe Borderline Personality Disorder  

PubMed Central

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

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

2014-01-01

276

Cerebellar networks with the cerebral cortex and basal ganglia  

PubMed Central

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

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

2013-01-01

277

Short latency cerebellar modulation of the basal ganglia.  

PubMed

The graceful, purposeful motion of our body is an engineering feat that 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. We found that the cerebellum rapidly modulates the activity of the striatum via a disynaptic pathway in mice. Under physiological conditions, this short latency pathway was 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 relayed aberrant cerebellar activity to the basal ganglia to cause dystonia. PMID:25402853

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

2014-12-01

278

[Atypical cerebellar neurocytoma resembling a hemangioblastoma. A case report].  

PubMed

Through August 2013, 105 cases of intracranial extraventricular neurocytoma (EVN) had been described; 6% were located in cerebellum and 22% were atypical EVN. A rare morphologic form of neurocytoma, atypical EVN has had only 24 cases reported to date. Its prognosis is poorer than the typical central neurocytoma. This case report describes an atypical cerebellar EVN, a form that has not been reported yet, hence the interest of this article. We emphasise its cystic nature and mural nodule, in an infrequent presentation. EVN are low-incidence tumours that we need to take into consideration when making the differential diagnosis of cystic cerebellar lesions with mural nodule. Given that the prognosis of atypical EVNs depends on the atypical nature and on the grade of resection, medical follow up has to be more constant, due to the greater degree of recurrence. PMID:24837842

Lista Martínez, Olalla; Rivas López, Luis Alfredo; Pombo Otero, Jorge Francisco; Amaro Cendón, Santiago; Bravo García, Christian; Villa Fernández, Juan Manuel

2014-01-01

279

Calcium signalling in granule neurones studied in cerebellar slices  

Microsoft Academic Search

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

Sergej Kirischuk; Nana Voitenko; Platon Kostyuk; Alexej Verkhratsky

1996-01-01

280

Acquisition of simple auditory and visual sequences in cerebellar patients  

Microsoft Academic Search

Previous studies suggest a role of the cerebellum in detecting and recognizing event sequences. In the present study sequences\\u000a of two acoustic tones of different frequencies and sequences of two visual stimuli with different colours were presented with\\u000a short, long and very long durations. Thirteen cerebellar patients and 13 controls were required to indicate whether the order\\u000a of stimuli was

Markus Frings; Matthias Maschke; Marcus Gerwig; Dagmar Timmann

2006-01-01

281

Functional Imaging of the Deep Cerebellar Nuclei: A Review  

Microsoft Academic Search

The present mini-review focused on functional imaging of human deep cerebellar nuclei, mainly the dentate nucleus. Although\\u000a these nuclei represent the unique output channel of the cerebellum, few data are available concerning their functional role.\\u000a However, the dentate nucleus has been shown to participate in a widespread functional network including sensorimotor and associative\\u000a cortices, striatum, hypothalamus, and thalamus, and plays

Christophe Habas

2010-01-01

282

Recurrent Cerebellar Hemorrhage: Case Report and Review of the Literature  

Microsoft Academic Search

We report a case of cerebellar hemorrhage (CH) that recurred in other hemisphere after 4 months of the first attack. A 58-year-old\\u000a man presented with general weakness and computerized tomography (CT) of the brain showed a 41 mm hematoma in the right cerebellum\\u000a with intraventricular extension. The satisfactory outcome was obtained after emergency surgical intervention and intensive\\u000a rehabilitation. However, the patient irregularly

Yung-Tsan Wu; Ming-Fu Hsieh; Heng-Yi Chu; Shao-Chi Lu; Shin-Tsu Chang; Tsung-Ying Li

2010-01-01

283

Asymptomatic remote cerebellar hemorrhage: CT and MRI findings.  

PubMed

The aim of this study was to evaluate the computed tomography (CT) and magnetic resonance imaging findings (MRI) of asymptomatic remote cerebellar hemorrhage (RCH) at the preoperative, early postoperative, and postoperative period. A total of 983 consecutive adult patients who underwent supratentorial craniotomies were included in the study. The ethics committee approved the study. The patient's clinical records and radiological examinations were retrospectively analyzed. All patients had preoperative CT and MRI examinations, immediate postoperative CT, and postoperative MRI within 24 h. The patients with the radiological diagnosis of RCH were followed up to 5 years. Eight asymptomatic RCH cases were recruited. The prevalence of asymptomatic RCH was 0.8% in our series. RCH was unilateral in two patients and bilateral in six patients. The postoperative CT was positive in two cases. The hemorrhage presented on MRI as folial linear hypointensities in six cases. In three cases (including one mixed case), punctate hypointense spots were identified at the superior cerebellar folia. Diffuse hemorrhage in the cerebellar tonsil, subarachnoid hemorrhage, and hemorrhage in the cerebellar vermis and the ventricles were also seen. The MRI findings were stable up to 5 years. The prevalence of asymptomatic RCH is higher than previously reported. Immediate postoperative CT is usually unremarkable; however, MRI demonstrates various hemorrhagic patterns at the cerebellum other than classical "zebra sign". This condition is self-limiting and no further investigation or follow-up study is required. In the proper clinical setting, the awareness of different hemorrhagic patterns in patients with RCH would prevent unnecessary investigations. PMID:22249914

Dincer, Alp; Özcan, Ümit; Kaya, Dilaver; Usseli, M Imre; Erzen, Canan; Pamir, M Necmettin

2012-12-01

284

Electrophysiological monitoring of injury progression in the rat cerebellar cortex  

PubMed Central

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.

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

2014-01-01

285

Atmospheric Environments for Entry, Descent and Landing (EDL)  

NASA Technical Reports Server (NTRS)

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.

Justus, Carl G.; Braun, Robert D.

2007-01-01

286

Pharmacogenomics of warfarin in populations of African descent  

PubMed Central

Warfarin is the most commonly prescribed oral anticoagulant worldwide despite its narrow therapeutic index and the notorious inter- and intra-individual variability in dose required for the target clinical effect. Pharmacogenetic polymorphisms are major determinants of warfarin pharmacokinetic and dynamics and included in several warfarin dosing algorithms. This review focuses on warfarin pharmacogenomics in sub-Saharan peoples, African Americans and admixed Brazilians. These ‘Black’ populations differ in several aspects, notably their extent of recent admixture with Europeans, a factor which impacts on the frequency distribution of pharmacogenomic polymorphisms relevant to warfarin dose requirement for the target clinical effect. Whereas a small number of polymorphisms in VKORC1 (3673G > A, rs9923231), CYP2C9 (alleles *2 and *3, rs1799853 and rs1057910, respectively) and arguably CYP4F2 (rs2108622), may capture most of the pharmacogenomic influence on warfarin dose variance in White populations, additional polymorphisms in these, and in other, genes (e.g. CALU rs339097) increase the predictive power of pharmacogenetic warfarin dosing algorithms in the Black populations examined. A personalized strategy for initiation of warfarin therapy, allowing for improved safety and cost-effectiveness for populations of African descent must take into account their pharmacogenomic diversity, as well as socio-economical, cultural and medical factors. Accounting for this heterogeneity in algorithms that are ‘friendly’ enough to be adopted by warfarin prescribers worldwide requires gathering information from trials at different population levels, but demands also a critical appraisal of racial/ethnic labels that are commonly used in the clinical pharmacology literature but do not accurately reflect genetic ancestry and population diversity. PMID:22676711

Suarez-Kurtz, Guilherme; Botton, Mariana R

2013-01-01

287

Cyclic coordinate descent: A robotics algorithm for protein loop closure  

PubMed Central

In protein structure prediction, it is often the case that a protein segment must be adjusted to connect two fixed segments. This occurs during loop structure prediction in homology modeling as well as in ab initio structure prediction. Several algorithms for this purpose are based on the inverse Jacobian of the distance constraints with respect to dihedral angle degrees of freedom. These algorithms are sometimes unstable and fail to converge. We present an algorithm developed originally for inverse kinematics applications in robotics. In robotics, an end effector in the form of a robot hand must reach for an object in space by altering adjustable joint angles and arm lengths. In loop prediction, dihedral angles must be adjusted to move the C-terminal residue of a segment to superimpose on a fixed anchor residue in the protein structure. The algorithm, referred to as cyclic coordinate descent or CCD, involves adjusting one dihedral angle at a time to minimize the sum of the squared distances between three backbone atoms of the moving C-terminal anchor and the corresponding atoms in the fixed C-terminal anchor. The result is an equation in one variable for the proposed change in each dihedral. The algorithm proceeds iteratively through all of the adjustable dihedral angles from the N-terminal to the C-terminal end of the loop. CCD is suitable as a component of loop prediction methods that generate large numbers of trial structures. It succeeds in closing loops in a large test set 99.79% of the time, and fails occasionally only for short, highly extended loops. It is very fast, closing loops of length 8 in 0.037 sec on average. PMID:12717019

Canutescu, Adrian A.; Dunbrack, Roland L.

2003-01-01

288

A Cerebellar Deficit in Sensorimotor Prediction Explains Movement Timing Variability  

PubMed Central

A popular theory is that the cerebellum functions as a timer for clocking motor events (e.g., initiation, termination). Consistent with this idea, cerebellar patients have been reported to show greater deficits during hand movements that repeatedly start and stop (i.e., discontinuous movements) compared with continuous hand movements. Yet, this finding could potentially be explained by an alternate theory in which the cerebellum acts as an internal model of limb mechanics. We tested whether a timing or internal model hypothesis best explains results from a circle-drawing task, where individuals trace a circle with the hand at a desired tempo. We first attempted to replicate prior results showing greater impairment for discontinuous versus continuous circling movements, and then asked whether we could improve patient performance by reducing demands in each domain. First, we slowed the movement down to reduce the need to predict and compensate for limb dynamics. Second, we supplied external timing information to reduce the need for an internal event timer. Results showed that we did not replicate the previous findings—cerebellar patients were impaired in both discontinuous and continuous movements. Slowing the movement improved cerebellar performance to near control values. The addition of an external visual timing signal paradoxically worsened timing deficits rather than mitigating them. One interpretation of these combined results is that the cerebellum is indeed functioning as an internal model and is needed to make appropriate predictions for movement initiation and termination. PMID:18815350

Bo, Jin; Block, Hannah J.; Clark, Jane E.; Bastian, Amy J.

2008-01-01

289

Laminar fate and phenotype specification of cerebellar GABAergic interneurons.  

PubMed

In most CNS regions, the variety of inhibitory interneurons originates from separate pools of progenitors residing in discrete germinal domains, where they become committed to specific phenotypes and positions during their last mitosis. We show here that GABAergic interneurons of the rodent cerebellum are generated through a different mechanism. Progenitors for these interneurons delaminate from the ventricular neuroepithelium of the embryonic cerebellar primordium and continue to proliferate in the prospective white matter during late embryonic and postnatal development. Young postmitotic interneurons do not migrate immediately to their final destination, but remain in the prospective white matter for several days. The different interneuron categories are produced according to a continuous inside-out positional sequence, and cell identity and laminar placement in the cerebellar cortex are temporally related to birth date. However, terminal commitment does not occur while precursors are still proliferating, and postmitotic cells heterochronically transplanted to developing cerebella consistently adopt host-specific phenotypes and positions. However, solid grafts of prospective white matter implanted into the adult cerebellum, when interneuron genesis has ceased, produce interneuron types characteristic of the donor age. Therefore, specification of cerebellar GABAergic interneurons occurs through a hitherto unknown process, in which postmitotic neurons maintain broad developmental potentialities and their phenotypic choices are dictated by instructive cues provided by the microenvironment of the prospective white matter. Whereas in most CNS regions the repertoire of inhibitory interneurons is produced by recruiting precursors from different origins, in the cerebellum it is achieved by creating phenotypic diversity from a single source. PMID:19474334

Leto, Ketty; Bartolini, Alice; Yanagawa, Yukio; Obata, Kunihiko; Magrassi, Lorenzo; Schilling, Karl; Rossi, Ferdinando

2009-05-27

290

?-Catenin Is Critical for Cerebellar Foliation and Lamination  

PubMed Central

The cerebellum has a conserved foliation pattern and a well-organized layered structure. The process of foliation and lamination begins around birth. ?-catenin is a downstream molecule of Wnt signaling pathway, which plays a critical role in tissue organization. Lack of ?-catenin at early embryonic stages leads to either prenatal or neonatal death, therefore it has been difficult to resolve its role in cerebellar foliation and lamination. Here we used GFAP-Cre to ablate ?-catenin in neuronal cells of the cerebellum after embryonic day 12.5, and found an unexpected role of ?-catenin in determination of the foliation pattern. In the mutant mice, the positions of fissure formation were changed, and the meninges were improperly incorporated into fissures. At later stages, some lobules were formed by Purkinje cells remaining in deep regions of the cerebellum and the laminar structure was dramatically altered. Our results suggest that ?-catenin is critical for cerebellar foliation and lamination. We also found a non cell-autonomous role of ?-catenin in some developmental properties of major cerebellar cell types during specific stages. PMID:23691221

Wen, Jing; Yang, Hong-Bin; Zhou, Bing; Lou, Hui-Fang; Duan, Shumin

2013-01-01

291

Hippocampal and cerebellar mossy fibre boutons – same name, different function  

PubMed Central

Over a century ago, the Spanish anatomist Ramón y Cajal described ‘mossy fibres’ in the hippocampus and the cerebellum, which contain several presynaptic boutons. Technical improvements in recent decades have allowed direct patch-clamp recordings from both hippocampal and cerebellar mossy fibre boutons (hMFBs and cMFBs, respectively), making them ideal models to study fundamental properties of synaptic transmission. hMFBs and cMFBs have similar size and shape, but each hMFB contacts one postsynaptic hippocampal CA3 pyramidal neuron, while each cMFB contacts ?50 cerebellar granule cells. Furthermore, hMFBs and cMFBs differ in terms of their functional specialization. At hMFBs, a large number of release-ready vesicles and low release probability (<0.1) contribute to marked synaptic facilitation. At cMFBs, a small number of release-ready vesicles, high release probability (?0.5) and rapid vesicle reloading result in moderate frequency-dependent synaptic depression. These presynaptic mechanisms, in combination with faster postsynaptic currents of cerebellar granule cells compared with hippocampal CA3 pyramidal neurons, enable much higher transmission frequencies at cMFB compared with hMFB synapses. Analysing the underling mechanisms of synaptic transmission and information processing represents a fascinating challenge and may reveal insights into the structure–function relationship of the human brain. PMID:23297303

Delvendahl, Igor; Weyhersmüller, Annika; Ritzau-Jost, Andreas; Hallermann, Stefan

2013-01-01

292

Cerebellar cortical lamination and foliation require cyclin A2.  

PubMed

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

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; Schüller, Ulrich; Sicinski, Piotr; Rowitch, David

2014-01-15

293

Preferential destruction of cerebellar Purkinje cells by OX7-saporin.  

PubMed

Saporin, a plant toxin derived from Saponaria officinalis, disrupts protein synthesis by inactivating the 60S portion of the ribosomal complex. OX7 is a mouse monoclonal antibody directed against the Thy-1.1 receptor that is differentially expressed on subpopulations of central nervous system neurons. Disulfide conjugation of OX7 to saporin permits delivery of saporin to target neurons. OX7-saporin was used to study the behavioral and morphological consequences of selective destruction of cerebellar Purkinje cells which abundantly express the Thy-1.1 antigen. Male Sprague-Dawley rats received bilateral intraventricular injections of 1- or 2 microg OX7-saporin or 8 microl artificial CSF. Rats were tested for behavioral changes 1 week before and 1, 2, and 8 weeks post-treatment. OX7-saporin treatment resulted in dose- and time-dependent changes in motor performance, activity, and negative geotaxis, but did not affect foot splay. Following behavioral testing, cerebellar sections were prepared for microscopic examination and the pattern of Purkinje cell loss was determined in anatomically matched sections. OX7-saporin induced dose-dependent death of Purkinje cells, particularly in the anterior and superior portions of cerebellar folia 1-6 and folium 9. Other brain regions appeared largely unaffected. Data suggest that intraventricular injection of rats with OX7-saporin is an effective model with which to examine the consequences of Purkinje cell destruction. PMID:10894129

Angner, R T; Kelly, R M; Wiley, R G; Walsh, T J; Reuhl, K R

2000-06-01

294

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

Microsoft Academic Search

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

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

2010-01-01

295

Adams Oliver syndrome: Description of a new phenotype with cerebellar abnormalities in a family  

PubMed Central

Summary Background To describe cerebellar abnormalities in a family composed by a father and two affected sibs with Adams Oliver syndrome (AOS) (OMIM 100300). Material/Methods Brain MRI and MR angiography were performed at 1.5T. Results The siblings presented cerebellar cortex dysplasia characterized by the presence of cysts. Conclusions Abnormalities of CNS are an unusual manifestation of AOS. To our knowledge, this is the first report of cerebellar cortical dysplasia in a family with AOS. PMID:24505229

D'Amico, Alessandra; Melis, Daniela; D'Arco, Felice; Di Paolo, Nilde; Carotenuto, Barbara; D'Anna, Gennaro; Russo, Carmela; Boemio, Pasquale; Brunetti, Arturo

2013-01-01

296

Functional organization of the vestibular afferents to the cerebellar cortex of frog and cat  

Microsoft Academic Search

1.Field and unitary potentials evoked in the vestibulo-cerebellum of frog and cat following vestibular nerve stimulation were recorded with microelectrodes and correlated with their site of origin in the various layers of the cerebellar cortex.2.In the frog, primary vestibular fibers project both as mossy and as climbing fibers onto the cerebellar auricular lobe. Secondary vestibulo-cerebellar fibers seem to end exclusively

W. PtCECHT; R. Llinás

1969-01-01

297

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

PubMed Central

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

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

2013-01-01

298

Cerebellar influence on olivary excitability in the cat.  

PubMed

This study examines the influence of the cerebellum on the excitability of inferior olivary neurons in the cat. Two major pathways from the cerebellar nuclei to the inferior olive have been investigated by electrophysiological and anatomical techniques. The first, excitatory pathway connects the cerebellar nuclei through nuclei at the mesodiencephalic junction with the inferior olive. The second is the direct, GABAergic, nucleo-olivary pathway. Intra- as well as extracellular recordings obtained in the rostral part of the medial accessory and principal olives revealed that electrical stimulation with a short burst of three pulses delivered at the mesodiencephalic junction results in short-latency activation (4-8 ms) of most olivary neurons. More than half of the units showed, in addition to the short-latency activation, a consistent response with a much longer latency (approximately 180 ms). Many units (66%) that responded to mesodiencephalic stimulation could also be activated by superior cerebellar peduncle stimulation with a similar stimulation paradigm (latency 9-15 ms). However, in such cases consistent long-latency responses were only rarely recorded (7%). To distinguish between the effect of the two pathways, both of which are activated by superior cerebellar peduncle stimulation, an electrolytic lesion of the nucleo-olivary fibres was made in the brainstem in six experiments. The effect of this lesion was verified in three cases by retrograde horseradish peroxidase tracing from the rostral inferior olive at the end of the experiment. This time only extracellular recordings were made. Stimulation of the mesodiencephalic junction still resulted in easily activated olivary units which showed an increased probability of firing a long-latency action potential. Stimulation of the superior cerebellar peduncle now resulted in a 50% decrease in probability of activating olivary units in the short-latency range. However, a five-fold increase in the chance of triggering action potentials in the long-latency interval was noted, implying that many units reacted only with a long-latency action potential. The results obtained with our experimental paradigm appear enigmatic since it is well established that the nucleo-olivary pathway is GABAergic and thus, by convention, should be inhibitory to the olivary neurons. However, it is possible to explain these results in terms of dynamic coupling of olivary neurons. This concept ascribes an important role to the nucleo-olivary pathway in regulating the degree of electrotonic coupling between olivary neurons (probably by a shunting mechanism) and as such may be an important instrument in the regulation of synchronous and rhythmic olivary discharges.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7542527

Ruigrok, T J; Voogd, J

1995-04-01

299

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

PubMed

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

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

2011-12-01

300

Aerodynamics of Reentry Vehicle Clipper at Descent Phase  

NASA Astrophysics Data System (ADS)

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.

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

2005-02-01

301

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

NASA Technical Reports Server (NTRS)

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.

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

302

Correlation of LMP10 Expression and Clinical Outcome in Human Papillomavirus (HPV) Positive and HPV-Negative Tonsillar and Base of Tongue Cancer  

PubMed Central

Aim To examine LMP10 expression and its possible impact on clinical outcome in human papillomavirus (HPV) positive and HPV-negative tonsillar and base of tongue squamous cell carcinoma (TSCC and BOTSCC). Background Outcome is better in HPV-positive TSCC and BOTSCC compared to matching HPV-negative tumours, with roughly 80% vs. 40% 5-year disease free survival (DFS) with less aggressive treatment than today’s chemoradiotherapy. Since current treatment often results in harmful side effects, less intensive therapy, with sustained patient survival would be an attractive alternative. However, other markers together with HPV status are necessary to select patients and for this purpose LMP10 expression is investigated here in parallel to HPV status and clinical outcome. Materials and Methods From 385 patients diagnosed between 2000 and 2007 at the Karolinska University Hospital, 278 formalin fixed paraffin embedded TSCC and BOTSCC biopsies, with known HPV DNA status, were tested for LMP10 nuclear and cytoplasmic expression (fraction of positive cells and staining intensity). The data was then correlated to clinical outcome. Results An absent/low compared to a moderate/high LMP10 nuclear fraction of positive cells was correlated to a better 3-year DFS in the HPV-positive group of patients (log-rank p?=?0.005), but not in the HPV-negative group. In the HPV-negative group of patients, in contrast to the HPV-positive group, moderate/high LMP10 cytoplasmic fraction and weak/moderate/high LMP10 cytoplasmic intensity correlated to a better 3-year DFS (p?=?0.003 and p?=?0.001) and 3-year overall survival (p?=?0.001 and 0.009). Conclusion LMP10 nuclear expression in the HPV-positive group and LMP10 cytoplasmic expression in the HPV-negative group of patients correlated to better clinical outcome. PMID:24752327

Tertipis, Nikolaos; Haeggblom, Linnea; Nordfors, Cecilia; Grun, Nathalie; Nasman, Anders; Vlastos, Andrea

2014-01-01

303

Robotic radiosurgery vs. brachytherapy as a boost to intensity modulated radiotherapy for tonsillar fossa and soft palate tumors: the clinical and economic impact of an emerging technology.  

PubMed

As a basis for making decisions regarding optimal treatment for patients with tonsillar fossa and soft palate tumors, we conducted a preliminary investigation of costs and quality of life (QoL) for two modalities [brachytherapy (BT) and robotic radiosurgery] used to boost radiation to the primary tumors following external beam radiotherapy. BT was well established in our center; a boost by robotic radiosurgery was begun more recently in patients for whom BT was not technically feasible. Robotic radiosurgery boost treatment has the advantage of being non-invasive and is able to reach tumors in cases where there is deep parapharyngeal tumor extension. A neck dissection was performed for patients with nodal-positive disease. Quality of life (pain and difficulty swallowing) was established in long-term follow-up for patients undergoing BT and over a one-year follow-up in robotic radiosurgery patients. Total hospital costs for both groups were computed. Our results show that efficacy and quality of life at one year are comparable for BT and robotic radiosurgery. Total cost for robotic radiosurgery was found to be less than BT primarily due to the elimination of hospital admission and operating room expenses. Confirmation of robotic radiosurgery treatment efficacy and reduced morbidity in the long term requires further study. Quality of life and cost analyses are critical to Health Technology Assessments (HTA). The present study shows how a preliminary HTA of a new medical technology such as robotic radiosurgery with its typical hypofractionation characteristics might be based on short-term clinical outcomes and assumptions of equivalence. PMID:17994791

Nijdam, W; Levendag, P; Fuller, D; Schulz, R; Prevost, J-B; Noever, I; Uyl-de Groot, C

2007-12-01

304

Intraparenchymal grafting of cerebellar cell suspensions to the deep cerebellar nuclei of pcd mutant mice, with particular emphasis on re-establishment of a Purkinje cell cortico-nuclear projection  

Microsoft Academic Search

In transplanting embryonic cerebellar grafts to the cerebellar cortex of “Purkinje cell degeneration” (pcd) mutant mice to replace missing Purkinje cells (PC), donor PC leave the graft and migrate to the molecular layer of the host. However, PC axons do not always reach the deep cerebellar nuclei of the host, which would be a key element in restoring much of

Lazaros C. Triarhou; Walter C. Low; Bernardino Ghetti I

1992-01-01

305

Deficits in phasic muscle force generation explain insufficient compensation for interaction torque in cerebellar patients  

Microsoft Academic Search

A simple paradigm was used to investigate how patients with cerebellar lesions cope with the need to correct for joint interactions during a multi-joint movement. Normal subjects and patients with cerebellar degeneration performed fast unconstrained elbow flexions with the instruction to voluntarily fixate the shoulder joint. Angular kinematics and inverse dynamics analyses were performed. A susceptibility index quantified how strong-concomitant

A. Boose; J. Dichgans; H. Topka

1999-01-01

306

Load compensation tasks evoke tremor in cerebellar patients: the possible role of long latency stretch reflexes  

Microsoft Academic Search

`Tremor' is one of the clinical signs of cerebellar dysfunction. Its nature remains subject to debate, one hypothesis being that of a predominant role of peripheral afferences in its genesis. This study was designed to study whether load compensating tasks, evoking sudden stretch, and thus stimulation of peripheral afferences induced tremor in cerebellar patients. We study the kinematics and EMG

Isabelle Richard; Michel Guglielmi; Robert Boisliveau; Brigitte Perrouin-Verbe; Isabelle Mauduyt de la Grève; Bernard Bioulac; Pierre Guiheneuc; Jean-François Mathé

1997-01-01

307

Overarm throwing speed in cerebellar subjects: effect of timing of ball release  

Microsoft Academic Search

Cerebellar subjects cannot throw fast and show variability in ball speed from throw to throw. One possible reason is that they release the ball at times when arm speed is not at its maximal value. Therefore, we investigated the hypothesis that the slow and variable speeds of throws made by cerebellar subjects are caused by their known large variability in

S. McNaughton; D. Timmann; S. Watts; J. Hore

2004-01-01

308

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

ERIC Educational Resources Information Center

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…

Brookes, Rebecca L.; Stirling, John

2005-01-01

309

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

ERIC Educational Resources Information Center

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

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

2005-01-01

310

Experience-dependent changes in cerebellar contributions to motor sequence learning  

E-print Network

of the cerebellum in motor skill learning. Yet, the relative impor- tance of the cerebellar cortex and deep nucleiExperience-dependent changes in cerebellar contributions to motor sequence learning Julien Doyon-related structures during learning, remains in dispute. Using functional magnetic resonance imaging and a motor se

Baker, Chris I.

311

Cerebellar dentate nuclei lesions reduce motivation in appetitive operant conditioning and open field exploration  

Microsoft Academic Search

Recently identified pathways from the dentate nuclei of the cerebellum to the rostral cerebral cortex via the thalamus suggest a cerebellar role in frontal and prefrontal non-motor functioning. Disturbance of cerebellar morphology and connectivity, particularly involving these cerebellothalamocortical (CTC) projections, has been implicated in motivational and cognitive deficits. The current study explored the effects of CTC disruption on motivation in

David J. Bauer; Abigail L. Kerr; Rodney A. Swain

2011-01-01

312

Speech Rate and Rhythm in Cerebellar Dysarthria: An Acoustic Analysis of Syllabic Timing  

Microsoft Academic Search

Auditory-perceptual studies reported inconsistent data with respect to syllabic timing in cerebellar dysarthria, i.e. both reduced and increased variability of syllable durations. The present study performed a comprehensive analysis of syllabic timing during sentence utterances in 14 subjects with a pure cerebellar syndrome (CA). First, the CA patients presented with reduced speech tempo in terms of syllable and utterance durations.

Hermann Ackermann; Ingo Hertrich

1994-01-01

313

Purkinje cell and cerebellar effects following developmental exposure to PCBs and\\/or MeHg  

Microsoft Academic Search

We recently reported that rats exposed to PCBs and MeHg during development were impaired on the rotating rod, a test of balance and coordination that is often indicative of cerebellar damage. In addition, developmental PCB exposure is known to dramatically reduce circulating thyroid hormone concentrations, which may have a negative impact on cerebellar development. Therefore, we investigated the effects of

Cindy S. Roegge; John R. Morris; Sherilyn Villareal; Victor C. Wang; Brian E. Powers; Anna Y. Klintsova; William T. Greenough; Isaac N. Pessah; Susan L. Schantz

2006-01-01

314

Synaptic Inhibition, Excitation, and Plasticity in Neurons of the Cerebellar Nuclei  

E-print Network

of activity predicted to occur during eyelid conditioning, suggesting that this form long-term potentiation cerebellar learning. Keywords Purkinje . Deep cerebellar nuclei . Rebound . Delay eyeblink . Long-term potentiation (LTP) . Long-term depression (LTD) Introduction The output of the cerebellum, with the exception

Raman, Indira M.

315

Epidemiology of Cerebellar Ataxia on the Etiological Basis: A Cross Sectional Study  

Microsoft Academic Search

Cerebellar ataxias are a heterogenous group of disorders, clinically and etiologically, that result in considerable health burden. Finding out about the various etiologies, and their relative prevalences in the population suffering from cerebellar ataxia helps the clinician to perform a better management, in treatment process. This is a cross sectional study designed to estimate the relative prevalence of each etiologic

Shahriar Nafissi; Ahmad Maghdouri; Hajir Sikaroodi; Simindokht Hosseini

316

Cerebellar Tasks do not Distinguish Between Children with Developmental Dyslexia and Children with Intellectual Disability  

Microsoft Academic Search

This paper explored the claim that only children with developmental dyslexia, whose reading ability is discrepant from their average general reasoning ability show specific deficits in motor tasks assessing cerebellar functioning (Fawcett et al., 2001, Cerebellar tests differentiate between groups of poor readers with and without IQ discrepancy. J. Learning Disabilities, 34, 119) and rapid serial naming (RAN, Wolf &

Robert Savage

2007-01-01

317

Intact Ability to Learn Internal Models of Arm Dynamics in Huntington's Disease But Not Cerebellar Degeneration  

E-print Network

Intact Ability to Learn Internal Models of Arm Dynamics in Huntington's Disease But Not Cerebellar internal models of arm dynamics in Huntington's disease but not cerebellar degeneration. J Neurophysiol 93 reported that while on-line error correction was disturbed in patients with Huntington's disease (HD

Smith, Maurice

318

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

PubMed Central

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

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

1996-01-01

319

Regular Patterns in Cerebellar Purkinje Cell Simple Spike Trains  

PubMed Central

Background Cerebellar Purkinje cells (PC) in vivo are commonly reported to generate irregular spike trains, documented by high coefficients of variation of interspike-intervals (ISI). In strong contrast, they fire very regularly in the in vitro slice preparation. We studied the nature of this difference in firing properties by focusing on short-term variability and its dependence on behavioral state. Methodology/Principal Findings Using an analysis based on CV2 values, we could isolate precise regular spiking patterns, lasting up to hundreds of milliseconds, in PC simple spike trains recorded in both anesthetized and awake rodents. Regular spike patterns, defined by low variability of successive ISIs, comprised over half of the spikes, showed a wide range of mean ISIs, and were affected by behavioral state and tactile stimulation. Interestingly, regular patterns often coincided in nearby Purkinje cells without precise synchronization of individual spikes. Regular patterns exclusively appeared during the up state of the PC membrane potential, while single ISIs occurred both during up and down states. Possible functional consequences of regular spike patterns were investigated by modeling the synaptic conductance in neurons of the deep cerebellar nuclei (DCN). Simulations showed that these regular patterns caused epochs of relatively constant synaptic conductance in DCN neurons. Conclusions/Significance Our findings indicate that the apparent irregularity in cerebellar PC simple spike trains in vivo is most likely caused by mixing of different regular spike patterns, separated by single long intervals, over time. We propose that PCs may signal information, at least in part, in regular spike patterns to downstream DCN neurons. PMID:17534435

Shin, Soon-Lim; Hoebeek, Freek E.; Schonewille, Martijn; De Zeeuw, Chris I.; Aertsen, Ad; De Schutter, Erik

2007-01-01

320

Properties of bilateral spinocerebellar activation of cerebellar cortical neurons  

PubMed Central

We aimed to explore the cerebellar cortical inputs from two spinocerebellar pathways, the spinal border cell-component of the ventral spinocerebellar tract (SBC-VSCT) and the dorsal spinocerebellar tract (DSCT), respectively, in the sublobule C1 of the cerebellar posterior lobe. The two pathways were activated by electrical stimulation of the contralateral lateral funiculus (coLF) and the ipsilateral LF (iLF) at lower thoracic levels. Most granule cells in sublobule C1 did not respond at all but part of the granule cell population displayed high-intensity responses to either coLF or iLF stimulation. As a rule, Golgi cells and Purkinje cell simple spikes responded to input from both LFs, although Golgi cells could be more selective. In addition, a small population of granule cells responded to input from both the coLF and the iLF. However, in these cases, similarities in the temporal topography and magnitude of the responses suggested that the same axons were stimulated from the two LFs, i.e., that the axons of individual spinocerebellar neurons could be present in both funiculi. This was also confirmed for a population of spinal neurons located within known locations of SBC-VSCT neurons and dorsal horn (dh) DSCT neurons. We conclude that bilateral spinocerebellar responses can occur in cerebellar granule cells, but the VSCT and DSCT systems that provide the input can also be organized bilaterally. The implications for the traditional functional separation of VSCT and DSCT systems and the issue whether granule cells primarily integrate functionally similar information or not are discussed. PMID:25386122

Geborek, Pontus; Bengtsson, Fredrik; Jörntell, Henrik

2014-01-01

321

Computation of egomotion in the macaque cerebellar vermis.  

PubMed

The nodulus and uvula (lobules X and IX of the vermis) receive mossy fibers from both vestibular afferents and vestibular nuclei neurons and are thought to play a role in spatial orientation. Their properties relate to a sensory ambiguity of the vestibular periphery: otolith afferents respond identically to translational (inertial) accelerations and changes in orientation relative to gravity. Based on theoretical and behavioral evidence, this sensory ambiguity is resolved using rotational cues from the semicircular canals. Recordings from the cerebellar cortex have identified a neural correlate of the brain's ability to resolve this ambiguity in the simple spike activities of nodulus/uvula Purkinje cells. This computation, which likely involves the cerebellar circuitry and its reciprocal connections with the vestibular nuclei, results from a remarkable convergence of spatially- and temporally-aligned otolith-driven and semicircular canal-driven signals. Such convergence requires a spatio-temporal transformation of head-centered canal-driven signals into an estimate of head reorientation relative to gravity. This signal must then be subtracted from the otolith-driven estimate of net acceleration to compute inertial motion. At present, Purkinje cells in the nodulus/uvula appear to encode the output of this computation. However, how the required spatio-temporal matching takes place within the cerebellar circuitry and what role complex spikes play in spatial orientation and disorientation remains unknown. In addition, the role of visual cues in driving and/or modifying simple and complex spike activity, a process potentially critical for long-term adaptation, constitutes another important direction for future studies. PMID:20012388

Angelaki, Dora E; Yakusheva, Tatyana A; Green, Andrea M; Dickman, J David; Blazquez, Pablo M

2010-06-01

322

Descent and Landing Triggers for the Orion Multi-Purpose Crew Vehicle Exploration Flight Test-1  

NASA Technical Reports Server (NTRS)

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.

Bihari, Brian D.; Semrau, Jeffrey D.; Duke, Charity J.

2013-01-01

323

Preliminary assessment of the Mars Science Laboratory entry, descent, and landing simulation  

NASA Astrophysics Data System (ADS)

On August 5, 2012, the Mars Science Laboratory rover, Curiosity, successfully landed inside Gale Crater. This landing was the seventh successful landing and fourth rover to be delivered to Mars. Weighing nearly one metric ton, Curiosity is the largest and most complex rover ever sent to investigate another planet. Safely landing such a large payload required an innovative Entry, Descent, and Landing system, which included the first guided entry at Mars, the largest supersonic parachute ever flown at Mars, and the novel Sky Crane landing system. A complete, end-to-end, six degree-of-freedom, multi-body computer simulation of the Mars Science Laboratory Entry, Descent, and Landing sequence was developed at the NASA Langley Research Center. In-flight data gathered during the successful landing is compared to pre-flight statistical distributions, predicted by the simulation. These comparisons provide insight into both the accuracy of the simulation and the overall performance of the Entry, Descent, and Landing system.

Way, David W.

324

Early cerebellar degeneration in twins with infantile neuroaxonal dystrophy.  

PubMed

Dizygotic twin girls with typical infantile neuroaxonal dystrophy (INAD) were studied at age 19 months with computed tomography and magnetic resonance imaging (MRI). Both methods showed distinct atrophy confined to the cerebellum and MRI revealed diffuse signal abnormality of the cerebellar parenchyma. This neuro-imaging evidence for selective early involvement of the cerebellum is consistent with both the typical presenting symptoms and the gross pathological findings in the disorder. Neuroimaging may aid in differentiation of INAD from other neurodegenerative disorders with onset in late infancy, providing impetus for diagnostic biopsy and early genetic counseling. PMID:2540694

Barlow, J K; Sims, K B; Kolodny, E H

1989-04-01

325

Fingolimod Attenuates Splenocyte-Induced Demyelination in Cerebellar Slice Cultures  

PubMed Central

The family of sphingosine-1-phosphate receptors (S1PRs) is G-protein-coupled, comprised of subtypes S1PR1-S1PR5 and activated by the endogenous ligand S1P. The phosphorylated version of Fingolimod (pFTY720), an oral therapy for multiple sclerosis (MS), induces S1PR1 internalisation in T cells, subsequent insensitivity to S1P gradients and sequestering of these cells within lymphoid organs, thus limiting immune response. S1PRs are also expressed in neuronal and glial cells where pFTY720 is suggested to directly protect against lysolecithin-induced deficits in myelination state in organotypic cerebellar slices. Of note, the effect of pFTY720 on immune cells already migrated into the CNS, prior to treatment, has not been well established. We have previously found that organotypic slice cultures do contain immune cells, which, in principle, could also be regulated by pFTY720 to maintain levels of myelin. Here, a mouse organotypic cerebellar slice and splenocyte co-culture model was thus used to investigate the effects of pFTY720 on splenocyte-induced demyelination. Spleen cells isolated from myelin oligodendrocyte glycoprotein immunised mice (MOG-splenocytes) or from 2D2 transgenic mice (2D2-splenocytes) both induced demyelination when co-cultured with mouse organotypic cerebellar slices, to a similar extent as lysolecithin. As expected, in vivo treatment of MOG-immunised mice with FTY720 inhibited demyelination induced by MOG-splenocytes. Importantly, in vitro treatment of MOG- and 2D2-splenocytes with pFTY720 also attenuated demyelination caused by these cells. In addition, while in vitro treatment of 2D2-splenocytes with pFTY720 did not alter cell phenotype, pFTY720 inhibited the release of the pro-inflammatory cytokines such as interferon gamma (IFN?) and interleukin 6 (IL6) from these cells. This work suggests that treatment of splenocytes by pFTY720 attenuates demyelination and reduces pro-inflammatory cytokine release, which likely contributes to enhanced myelination state induced by pFTY720 in organotypic cerebellar slices. PMID:24911000

Pritchard, Adam J.; Mir, Anis K.; Dev, Kumlesh K.

2014-01-01

326

Ionic mechanisms of autorhythmic firing in rat cerebellar Golgi cells.  

PubMed

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

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

2006-08-01

327

Application of a simple cerebellar model to geologic surface mapping  

USGS Publications Warehouse

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.

Hagens, A.; Doveton, J.H.

1991-01-01

328

Immunological reactivity against neuronal and non-neuronal antigens in sporadic adult-onset cerebellar ataxia.  

PubMed

In recent years, the involvement of the immune system in acquired forms of cerebellar ataxia has been frequently demonstrated. In this study, we describe 6 out of 49 patients with subacute or chronic progressive cerebellar ataxia in whom antibodies against neuronal and non-neuronal antigens were identified. Two women had anti-Yo antibodies; two patients had anti-gliadin antibodies in the presence of celiac disease; one patient had a complex autoimmune disorder associated with anti-Ro-52/SS-A and anti-muscle-specific kinase antibodies, and a patient developed subacute cerebellar syndrome associated with the presence of a prostatic adenocarcinoma and atypical antibodies reacting both with cerebellar tissue and with the prostatic tumor. Our study confirms previous findings in paraneoplastic syndromes, and indicates that at least 10% of sporadic cerebellar ataxia may be related to immune-mediated mechanisms. PMID:19786780

Fancellu, Roberto; Pareyson, Davide; Corsini, Elena; Salsano, Ettore; Laurà, Matilde; Bernardi, Gaetano; Antozzi, Carlo; Andreetta, Francesca; Colecchia, Maurizio; Di Donato, Stefano; Mariotti, Caterina

2009-01-01

329

Bilateral Superior Cerebellar Artery Infarction after Stent-Angioplasty for Internal Carotid Artery Stenosis  

PubMed Central

Spontaneous bilateral cerebellar infarction in the territory of the superior cerebellar arteries is extremely rare. Occasionally there have been reports of bilateral cerebellar infarction due to vertebrobasilar atherosclerotic occlusion or stenosis, whereas no report of bilateral cerebellar infarction due to complicated hemodynamic changes. In this report, we present a patient with bilateral cerebral infarctions related to stenoses of bilateral internal carotid arteries, in whom vertebrobasilar system was supplied by multiple collaterals from both posterior communicating arteries and right external carotid artery. We performed stent-angioplasty of bilateral internal cerebral arterial stenosis, and then acute infarction developed on bilateral superior cerebellar artery territories. The authors assumed that the infarction occurred due to hemodynamic change between internal carotid artery and external carotid artery after stent-angioplasty for stenosis of right internal carotid artery. PMID:24278655

Kim, Jung-Hwan; Lee, Jong-Hyeog; Jo, Kwang-Deog

2013-01-01

330

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

PubMed Central

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

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

2013-01-01

331

Entry, Descent and Landing Systems Analysis: Exploration Class Simulation Overview and Results  

NASA Technical Reports Server (NTRS)

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.

DwyerCianciolo, Alicia M.; Davis, Jody L.; Shidner, Jeremy D.; Powell, Richard W.

2010-01-01

332

Overview of the NASA Entry, Descent and Landing Systems Analysis Study  

NASA Technical Reports Server (NTRS)

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

Zang, Thomas A.; Dwyer-Cianciolo, Alicia M.; Kinney, David J.; Howard, Austin R.; Chen, George T.; Ivanov, Mark C.; Sostaric, Ronald R.; Westhelle, Carlos H.

2010-01-01

333

Cerebellar abnormalities in Huntington's disease: A role in motor and psychiatric impairment?  

PubMed

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. © 2014 International Parkinson and Movement Disorder Society. PMID:25123926

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

334

Compensation of oculomotor deficits in monkeys with neonatal cerebellar ablations.  

PubMed

The oculomotor performance of 11 monkeys, who had various degrees of cerebellar ablation shortly after birth, is described in this study. Detailed numerical results were obtained on three of these adult macaques after extensive training of specific pursuit eye movements and fixation. The vestibular nuclei were kept intact. In the presence of the intracerebellar nuclei, quite extensive neonatal ablations of the cerebellar cortex leave the adult monkey without any discernible oculomotor deficits. If ablation also includes the nuclei on one side, compensation is never complete even several years later: while vestibulo-ocular and saccadic responses seem normal, there are deficits in pursuit and gaze holding performance. The residual deficits vary with the extent of the ablation and are comparable with the pattern exhibited by acute hemicerebellar ablations. Monkeys who had their cerebellum including the nuclei essentially completely removed just after birth, could pursue, albeit with limited velocity, and hold gaze, albeit in a limited zone. Their vestibulo-ocular responses seemed unaffected. PMID:6641830

Eckmiller, R; Westheimer, G

1983-01-01

335

Cortico-cerebellar abnormalities in adolescents with heavy marijuana use.  

PubMed

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

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

2012-06-30

336

Influence of thyroid hormones on maturation of rat cerebellar astrocytes.  

PubMed

Thyroid hormone influences brain maturation through interaction with nuclear receptors and regulation of gene expression. Their role on astrocyte maturation remains unclear. We have analyzed the role of thyroid hormone in rat cerebellar astrocyte maturation by comparing the sequential patterns of intermediate filament expression in normal and hypothyroid animals. During normal development astroglial cells sequentially express nestin, vimentin, and glial fibrillary acidic protein. Differentiated astrocytes appeared in the superior medullary vellum by postnatal day 2 and reached the white mater and internal granular layer by postnatal day 4. Intermediate filament marker expression was transiently lost from postnatal days 6 to 8 in anterior lobes, without an increased apoptosis. Vimentin expression was replaced by glial fibrillary acidic protein between postnatal days 10 and 32. The differentiated astrocytes were evenly distributed throughout the cerebellar slices, including the internal granular layer. Differences between normal and hypothyroid rats were observed starting from postnatal day 4, with lack of differentiated astrocytes in the internal granular layer. The transient decrease of astrocyte markers immunoreactivity in the anterior lobe did not take place in hypothyroid rats. The vimentin-glial fibrillary acidic protein transition was delayed and most differentiated astrocytes remained confined to the white matter. The results indicate that thyroid hormone deficiency induces a delay and a partial arrest of astrocyte differentiation. Astrocytes express thyroid hormone receptor alpha and beta subtypes suggesting that astrocytes are direct target cells of thyroid hormones. PMID:17408906

Manzano, Jimena; Bernal, Juan; Morte, Beatriz

2007-05-01

337

Cerebellar inactivation impairs cross modal savings of eyeblink conditioning.  

PubMed

Eyeblink conditioning using a conditioned stimulus (CS) from one sensory modality (e.g., an auditory CS) is greatly enhanced when the subject is previously trained with a CS from a different sensory modality (e.g., a visual CS). The enhanced acquisition to the second modality CS results from cross modal savings. The current study was designed to examine the role of the cerebellum in establishing cross modal savings in eyeblink conditioning with rats. In the first experiment rats were given paired or unpaired presentations with a CS (tone or light) and an unconditioned stimulus. All rats were then given paired training with a different modality CS. Only rats given paired training showed cross modal savings to the second modality CS. Experiment 2 showed that cerebellar inactivation during initial acquisition to the first modality CS completely prevented savings when training was switched to the second modality CS. Experiment 3 showed that cerebellar inactivation during initial cross modal training also prevented savings to the second modality stimulus. These results indicate that the cerebellum plays an essential role in establishing cross modal savings of eyeblink conditioning. PMID:19331453

Campolattaro, Matthew M; Freeman, John H

2009-04-01

338

Excitation of cerebellar interneurons by group I metabotropic glutamate receptors.  

PubMed

Cerebellar basket and stellate neurons (BSNs) provide feed-forward inhibition to Purkinje neurons (PNs) and thereby play a principal role in determining the output of the cerebellar cortex. During low-frequency transmission, glutamate released at parallel fiber synapses excites BSNs by binding to AMPA receptors; high-frequency transmission also recruits N-methyl-d-aspartate (NMDA) receptors. We find that, in addition to these ligand-gated receptors, a G-protein-coupled glutamate receptor subtype participates in exciting BSNs. Stimulation of metabotropic glutamate receptor 1alpha (mGluR1alpha) with the mGluR agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) leads to an increase in spontaneous firing of BSNs and indirectly to an increase in the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) recorded in PNs. Under conditions in which ligand-gated glutamate receptors are blocked, parallel fiber stimulation generates a slow excitatory postsynaptic current (EPSC) in BSNs that is inhibited by mGluR1alpha-selective antagonists. This slow EPSC is capable of increasing BSN spiking and indirectly increasing sIPSCs frequency in PNs. Our findings reinforce the idea that distinct subtypes of glutamate receptors are activated in response to different patterns of activity at excitatory synapses. The results also raise the possibility that mGluR1alpha-dependent forms of synaptic plasticity may occur at excitatory inputs to BSNs. PMID:15152021

Karakossian, Movses H; Otis, Thomas S

2004-09-01

339

A new Kv1.2 channelopathy underlying cerebellar ataxia.  

PubMed

A forward genetic screen of mice treated with the mutagen ENU identified a mutant mouse with chronic motor incoordination. This mutant, named Pingu (Pgu), carries a missense mutation, an I402T substitution in the S6 segment of the voltage-gated potassium channel Kcna2. The gene Kcna2 encodes the voltage-gated potassium channel ?-subunit Kv1.2, which is abundantly expressed in the large axon terminals of basket cells that make powerful axo-somatic synapses onto Purkinje cells. Patch clamp recordings from cerebellar slices revealed an increased frequency and amplitude of spontaneous GABAergic inhibitory postsynaptic currents and reduced action potential firing frequency in Purkinje cells, suggesting that an increase in GABA release from basket cells is involved in the motor incoordination in Pgu mice. In line with immunochemical analyses showing a significant reduction in the expression of Kv1 channels in the basket cell terminals of Pgu mice, expression of homomeric and heteromeric channels containing the Kv1.2(I402T) ?-subunit in cultured CHO cells revealed subtle changes in biophysical properties but a dramatic decrease in the amount of functional Kv1 channels. Pharmacological treatment with acetazolamide or transgenic complementation with wild-type Kcna2 cDNA partially rescued the motor incoordination in Pgu mice. These results suggest that independent of known mutations in Kcna1 encoding Kv1.1, Kcna2 mutations may be important molecular correlates underlying human cerebellar ataxic disease. PMID:20696761

Xie, Gang; Harrison, John; Clapcote, Steven J; Huang, Yun; Zhang, Jin-Yi; Wang, Lu-Yang; Roder, John C

2010-10-15

340

Laminin ?1 is essential for mouse cerebellar development  

PubMed Central

Laminin ?1 (Lama1), which is a subunit of laminin-1 (laminin-111), a heterotrimeric ECM protein, is essential for embryonic development and promotes neurite outgrowth in culture. Because the deletion of Lama1 causes lethality at early embryonic stages in mice, the in vivo role of Lama1 in neural development and functions has not yet been possible to determine. In this study, we generated conditional Lama1 knockout (Lama1CKO) mice in the epiblast lineage using Sox2-Cre mice. These Lama1CKO mice survived, but displayed behavioral disorders and impaired formation of the cerebellum. Deficiency of Lama1 in the pial basement membrane of the meninges resulted in defects in the conformation of the meninges. During cerebellar development, Lama1 deficiency also caused a decrease in the proliferation and migration of granule cell precursors, disorganization of Bergmann glial fibers and endfeet, and a transient reduction in the activity of Akt. A marked reduction in numbers of dendritic processes in Purkinje cells was observed in Lama1CKO mice. Together, these results indicate that Lama1 is required for cerebellar development and functions. PMID:21983115

Ichikawa-Tomikawa, Naoki; Ogawa, Junko; Douet, Vanessa; Xu, Zhuo; Kamikubo, Yuji; Sakurai, Takashi; Kohsaka, Shinichi; Chiba, Hideki; Hattori, Nobutaka; Yamada, Yoshihiko; Arikawa-Hirasawa, Eri

2011-01-01

341

Bistability in Purkinje neurons: ups and downs in cerebellar research.  

PubMed

The output of cerebellar Purkinje cells has been characterized extensively and theories regarding the role of simple spike (SS) and complex spike (CS) patterns have evolved through many different studies. A bistable pattern of SS output can be observed in vitro; however, differing views exist regarding the occurrence of bistable SS output in vivo. Bistability in Purkinje cell output is characterized by abrupt transitions between tonic firing and quiescence, usually evoked by synaptic inputs to the neuron. This is in contrast to the trimodal pattern of activity which has been found in vitro and in vivo when climbing fiber input to Purkinje cells is removed. The mechanisms underlying bistable membrane properties in Purkinje cells have been determined through in vitro studies and computational analysis. In vitro studies have further established that Purkinje cells possess the ability to toggle between firing states, but in vivo studies in both awake and anesthetized animals have found conflicting results as to the presence of toggling in the intact circuit. Here, we provide an overview of the current state of research on bistability, examining the mechanisms underlying bistability and current findings from in vivo studies. We also suggest possible reasons for discrepancies between in vivo studies and propose future studies which would aid in clarifying the role of bistability in the cerebellar circuit. PMID:23041207

Engbers, Jordan D T; Fernandez, Fernando R; Turner, Ray W

2013-11-01

342

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

...oxygen for emergency descent and for first aid; turbine engine powered airplanes with...oxygen for emergency descent and for first aid; turbine engine powered airplanes with...passenger cabin occupants. (3) For first-aid treatment of occupants who for...

2014-01-01

343

A molecular signature of an arrest of descent in human parturition  

PubMed Central

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

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

344

Access to Health Care Among Latinos of Mexican Descent in "Colonias" in Two Texas Counties  

ERIC Educational Resources Information Center

Critical to resolving the problem of health disparities among Latinos is examining the needs within ethnic subpopulations. This paper focused on the unique challenges encountered by one ethnic subpopulation -- Latinos of Mexican descent living in colonias. Findings reaffirm the importance of looking within ethnic subpopulations to understand the…

Ortiz, Larry; Arizmendi, Lydia; Cornelius, Llewellyn J.

2004-01-01

345

Model reference adaptive control of a maglev system with stable maximum descent criterion  

Microsoft Academic Search

This paper develops a model-reference adaptive controller (MRC) design framework for magnetically suspended vehicles (maglev) using the criterion of stable maximum descent. The adaptation algorithm is constrained to reduce the airgap error between the reference model and the actual system. The explicit relationship between the parameters of the performance criterion (function of the airgap error and its derivative) and the

P. K. Sinha; Alexandre N. Pechev

1999-01-01

346

Sexual Health Discussions between African-American Mothers and Mothers of Latino Descent and Their Children  

ERIC Educational Resources Information Center

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.…

Murray, Ashley; Ellis, Monica U.; Castellanos, Ted; Gaul, Zaneta; Sutton, Madeline Y.; Sneed, Carl D.

2014-01-01

347

Education by Any Means Necessary: Peoples of African Descent and Community-Based Pedagogical Spaces  

ERIC Educational Resources Information Center

This study examines how and why peoples of African descent access and utilize community-based pedagogical spaces that exist outside schools. Employing a theoretical framework that fuses historical methodology and border-crossing theory, the researchers review existing scholarship and primary documents to present an historical examination of how…

Douglas, Ty-Ron Michael; Peck, Craig

2013-01-01

348

Localization of Mars rovers using descent and surface-based image data  

E-print Network

image data. The Mars Pathfinder Mission in 1997 clearly demonstrated the importance of mobility systems and Golombek, 1998; Golombek et al., 1997]. In the planned 2003 Mars Exploration Rover (MER) Mission two roversLocalization of Mars rovers using descent and surface-based image data Rongxing Li, Fei Ma

Olson, Clark F.

349

P-packSVM: Parallel Primal grAdient desCent Kernel SVM  

Microsoft Academic Search

It is an extreme challenge to produce a nonlinear SVM classifier on very large scale data. In this paper we describe a novel P-packSVM algorithm that can solve the support vector machine (SVM) optimization problem with an arbitrary kernel. This algorithm embraces the best known stochastic gradient descent method to optimize the primal objective, and has 1\\/¿ dependency in complexity

Zeyuan Allen Zhu; Weizhu Chen; Gang Wang; Chenguang Zhu; Zheng Chen

2009-01-01

350

Flight test and ISS application of the Inflatable Reentry and Descent Technology (IRDT)  

Microsoft Academic Search

The Inflatable Reentry and Descent Technology (IRDT) is an innovative light weight entry technology using an inflatable heatshield. The technology was originally developed by Lavochkin \\/ Babakin Space Center for the Mars-96 mission. Together with the European Space Agency, Astrium and the International Science and Technology Center the technology was further developed and tested in a first Earth renetry test

D. Vennemann; L. Marraffa; K. Pitchadze; S. Alexsaschkin

2002-01-01

351

Iron deficiency anaemia in women of south Asian descent: A qualitative study  

Microsoft Academic Search

Objective. Menorrhagia is thought to be the commonest cause of iron deficiency anaemia in women of reproductive age living in Britain. However, it has been suggested that the high prevalence of iron deficiency anaemia in women of South Asian descent living in Britain is due to religious and cultural restrictions on certain foods. While lack of iron in the diet,

Alison Chapple

1998-01-01

352

National Aeronautics and Space Administration Entry, DEscEnt, anD LanDing  

E-print Network

National Aeronautics and Space Administration Entry, DEscEnt, anD LanDing roaDmap Technology Area of fourteen technology area roadmaps, recommending the overall technology investment strategy of future advances possible in these areas, NASA plans updates to its integrated technology roadmap

Waliser, Duane E.

353

The Gods Must Be Crazy: The Denial of Descent in Academic Scholarship.  

ERIC Educational Resources Information Center

Expands the literature of discontent with academic scholarship by showing how malaise is grounded metaphorically in the uncritical celebration of "up" and the vilification of "down." Historicizes these metaphors through classical Greek poetry and philosophy to rediscover how flowing back and forth between Apollonian upness and Dionysian descent

Hocker Rushing, Janice; Frentz, Thomas S.

1999-01-01

354

A Fast Active Set Block Coordinate Descent Algorithm for l1 ...  

E-print Network

real-world problems (e.g. signal and image processing, compressive sensing, ... In [23], some ideas on how to speed up their Block Coordinate Descent .... Let xk ? IRn and i ? {1,...,n} be an index estimated active by our estimate, that is,.

2014-03-11

355

Impact of multiple submarine channels on the descent of dense water at high latitudes  

Microsoft Academic Search

A three-dimensional numerical hydrodynamic model is applied to examine the impact of multiple submarine channels (<10 km across, <100 m deep), common to most continental margins of the ocean, on the descent of dense water at high latitudes. The model consists of an ocean bottom layer of constant height that follows variable bottom topography under constant vertical grid spacing. An

Jochen Kämpf

2000-01-01

356

The Role of Educational Background, Activity, and Past Experiences in Mexican-Descent Families' Science Conversations.  

ERIC Educational Resources Information Center

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.)…

Tenenbaum, Harriet R.; Callanan, Maureen A.; Alba-Speyer, Consuelo; Sandoval, Leticia

2002-01-01

357

Identity by Descent Genome Segmentation Based on Single Nucleotide Polymorphism Distributions  

E-print Network

are made for the mutation rate in the human genome. Introduction High throughput genome sequence analysis-uniform. This finding is striking because SNPs are thought to arise by a mutation process that occurs with approximately to be identical by descent (IBD). The age of the last common ancestor for a segment is Copyright © 1999, American

Rouchka, Eric

358

Bulk chemical trends at arc volcanoes are not liquid lines of descent  

Microsoft Academic Search

Although the magmatic output of arc volcanoes defines clear chemical trends, the compositional sequence of eruption is often chaotic. At best, support for the concept of progressive evolution by fractionation\\/assimilation in a central chamber is ambiguous. Rather than defining a liquid line of descent, we suggest that chemical trends in arc systems are populated by discrete magma batches. These have

John C. Eichelberger; Pavel E. Izbekov; Brandon L. Browne

2006-01-01

359

The behavior of epididymis, processus vaginalis and testicular descent in cryptorchid boys treated with buserelin.  

PubMed

This randomized double-blind, placebo-controlled study was initiated to analyze the behavior of epididymis, processus vaginalis and testicular descent in cryptorchid boys treated with a low dose (20 micrograms) of a luteinizing hormone-releasing hormone analogue (Buserelin), administered daily, as a nasal spray, for a short period (28 days). Fifty-nine true cryptorchid boys were randomly assigned to 3 groups: buserelin treatment [22], surgical treatment [18] or placebo control group [19]. The 3 groups of patients were similar before treatment in regard to testicular position, chronological and bone age, height and weight, luteinizing hormone, follicle-stimulating hormone, testosterone, penile size and the volume of the contralateral descended testis. None of the patients had retractile testes. Buserelin significantly induced testicular descent compared to the boys treated with a placebo (P < 0.01). A normal epididymis was found more often in boys with successful descent (P < 0.003). A closed processus vaginalis was also more frequently observed in the group treated with buserelin than in surgically treated one (P < 0.05). In conclusion, buserelin was capable of inducing testicular descent besides provoking further development of the epididymis and closing the processus vaginalis. PMID:8101813

Bica, D T; Hadziselimovic, F

1993-01-01

360

A concept for the entry, descent, and landing of high-mass payloads at Mars  

Microsoft Academic Search

The architecture concepts and aggressive science objectives for the next phases of Mars exploration will require landed masses an order of magnitude or greater than any Mars mission previously planned or flown. Additional studies have shown the requirements for missions more ambitious than the 2009 Mars Science Laboratory (?900kg payload mass) to extend beyond the capabilities of Viking-heritage entry, descent,

Ashley M. Korzun; Gregory F. Dubos; Curtis K. Iwata; Benjamin A. Stahl; John J. Quicksall

2010-01-01

361

TITAN WIND EFFECTS ON THE DESCENT TRAJECTORY OF THE ESA HUYGENS PROBE B. Kazeminejad1  

E-print Network

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

Atkinson, David H.

362

Artist concept titled 'STS-30 Descent over California' produced by Rockwell  

NASA Technical Reports Server (NTRS)

Rockwell International (RI) supplied artist concept titled 'STS-30 Descent over California' shows Atlantis, Orbiter Vehicle (OV) 104, approach to Edwards Air Force Base (EAFB), California. Annotated ground track map identifies major events in landing sequence starting at the initiation of tactical air navigation (TACAN) updating and touch down minus (-) 10 minutes.

1989-01-01

363

DEVELOPMENT AND INITIAL FIELD EVALUATION OF FLIGHT DECK PROCEDURES FOR FLYING CTAS DESCENT CLEARANCES  

Microsoft Academic Search

The Center TRACON Automation System (CTAS) is a new computer-based system that will assist air traffic controllers in the management of arrival traffic. The Descent Advisor (DA), a major component of CTAS, uses an algorithm to predict flight trajectories and arrival times based on an aircraft's cruise airspeed, current air traffic, current atmospheric conditions, type-specific aircraft performance data and airline

Patricia Cashion; Michael Feary; Tsuyoshi Goka; Holly Graham; Everett Palmer; Nancy Smith

1995-01-01

364

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

E-print Network

+1 (818) 354-6770 balaram@jpl.nasa.gov 1 0-7803-7231-X/01/$10.00/© 2002 IEEE 2 IEEEAC paper #302, Updated October 1, 2001 Abstract--The Jet Propulsion Laboratory (JPL) is developing a high, DSENDS (Dynamics Simulator for Entry, Descent and Surface landing), is an EDL-specific extension of a JPL

365

Stochastic parallel gradient descent based adaptive optics used for a high contrast imaging coronagraph  

Microsoft Academic Search

An adaptive optics (AO) system based on a stochastic parallel gradient descent (SPGD) algorithm is proposed to reduce the speckle noises in the optical system of a stellar coronagraph in order to further improve the contrast. The principle of the SPGD algorithm is described briefly and a metric suitable for point source imaging optimization is given. The feasibility and good

Bing Dong; De-Qing Ren; Xi Zhang

2011-01-01

366

Qualitative Research with an Understudied Population: In-Depth Interviews with Women of Mexican Descent  

Microsoft Academic Search

Community-based qualitative research offers advantages for study of populations that are understudied and not well understood, but qualitative methodology presents major challenges. This article examines some of these challenges, illustrated by a study of pregnancy and childbearing among women of Mexican descent. Issues addressed in this article include culture and gender relevance, access to the population, representativeness, skilled interviewers, trust

Margaret Sherrard Sherraden; Rossana E. Barrera

1995-01-01

367

CS 3EA3: Example Haskell Code for Recursive Descent Parsing Wolfram Kahl  

E-print Network

CS 3EA3: Example Haskell Code for Recursive Descent Parsing Wolfram Kahl September 17, 2009 The module Data.Char provides us with the functions isDigit, isLetter, and ord :: Char Int. module ExprParse parsing: Expr ::= Term + Expr | Term Term ::= Factor * Term | Factor Factor ::= Number | Identifier

Carette, Jacques

368

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

NASA Technical Reports Server (NTRS)

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.

Dunn, Catherine; Prakash, Ravi

2008-01-01

369

Inference of Identity-by-Descent in Sib Pairs: Analysis with and without Linkage Disequilibrium  

E-print Network

Inference of Identity-by-Descent in Sib Pairs: Analysis with and without Linkage Disequilibrium Report Number 519 September, 2007. 1 #12;Abstract In gene mapping, after an initial genome-wide linkage genotyping, however, introduces linkage disequilibrium (LD). Traditional linkage analysis assuming no LD

Washington at Seattle, University of

370

Immune response to dietary proteins, gliadin and cerebellar peptides in children with autism.  

PubMed

The mechanisms behind autoimmune reaction to nervous system antigens in autism are not understood. We assessed the reactivity of sera from 50 autism patients and 50 healthy controls to specific peptides from gliadin and the cerebellum. A significant percentage of autism patients showed elevations in antibodies against gliadin and cerebellar peptides simultaneously. For examining cross-reaction between dietary proteins and cerebellar antigens, antibodies were prepared in rabbits, and binding of rabbit anti-gliadin, anti-cerebellar peptides, anti-MBP, anti-milk, anti-egg, anti-soy and anti-corn to either gliadin- or cerebellar-antigen-coated wells was measured. In comparison to anti-gliadin peptide binding to gliadin peptide at 100%, the reaction of anti-cerebellar peptide to gliadin peptide was 22%, whereas the binding of anti-myelin basic protein (MBP), anti-milk, anti-egg and anti-soy to gliadin was less than 10%. Further examination of rabbit anti-gliadin (EQVPLVQQ) and anti-cerebellar (EDVPLLED) 8 amino acid (AA) peptides with human serum albumin (HSA) and an unrelated peptide showed no binding, but the reaction of these antibodies with both the cerebellar and gliadin peptides was greater than 60%. This cross-reaction was further confirmed by DOT-immunoblot and inhibition studies. We conclude that a subgroup of patients with autism produce antibodies against Purkinje cells and gliadin peptides, which may be responsible for some of the neurological symptoms in autism. PMID:15526989

Vojdani, A; O'Bryan, T; Green, J A; Mccandless, J; Woeller, K N; Vojdani, E; Nourian, A A; Cooper, E L

2004-06-01

371

Relationships between regional cerebellar volume and sensorimotor and cognitive function in young and older adults  

PubMed Central

The cerebellum has been implicated in both sensorimotor and cognitive function, but is known to undergo volumetric declines with advanced age. Individual differences in regional cerebellar volume may therefore provide insight into performance variability across the lifespan, as has been shown with other brain structures and behaviors. Here, we investigated whether there are regional age differences in cerebellar volume in young and older adults, and whether these volumes explain, in part, individual differences in sensorimotor and cognitive task performance. We found that older adults had smaller cerebellar volume than young adults; specifically, lobules in the anterior cerebellum were more impacted by age. Multiple regression analyses for both age groups revealed associations between sensorimotor task performance in several domains (balance, choice reaction time, and timing) and regional cerebellar volume. There were also relationships with working memory, but none with measures of general cognitive or executive function. Follow-up analyses revealed several differential relationships with age between regional volume and sensorimotor performance. These relationships were predominantly selective to cerebellar regions that have been implicated in cognitive functions. Therefore, it may be the cognitive aspects of sensorimotor task performance that are best explained by individual differences in regional cerebellar volumes. In sum, our results demonstrate the importance of regional cerebellar volume with respect to both sensorimotor and cognitive performance, and we provide additional insight into the role of the cerebellum in age-related performance declines. PMID:23625382

Bernard, Jessica A.; Seidler, Rachael D.

2013-01-01

372

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

PubMed

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

Ferrucci, Roberta; Priori, Alberto

2014-01-15

373

Linking novelty seeking and harm avoidance personality traits to cerebellar volumes.  

PubMed

Personality traits are multidimensional traits comprising cognitive, emotional, and behavioral characteristics, and a wide array of cerebral structures mediate individual variability. Differences in personality traits covary with brain morphometry in specific brain regions, and neuroimaging studies showed structural or functional abnormalities of cerebellum in subjects with personality disorders, suggesting a cerebellar role in affective processing and an effect on personality characteristics. To test the hypothesis that cerebellar [white matter (WM) and cortex] volumes are correlated with scores obtained in the four temperamental scales of the Temperament and Character Inventory (TCI) by Cloninger, a total of 125 healthy participants aged 18-67 years of both genders (males = 52) completed the TCI and underwent magnetic resonance imaging. The scores obtained in each temperamental scale were associated with the volumes of cerebellar WM and cortex of right and left hemispheres separately by using linear regression analyses. In line with our hypothesis, novelty seeking (NS) scores were positively associated with WM and cortex cerebellar volumes. Harm avoidance (HA) scores were negatively associated with WM and cortex cerebellar volumes. The range of individual differences in NS and HA scores reflects the range of variances of cerebellar volumes. The present data indicating a cerebellar substrate for some personality traits extend the relationship between personality and brain areas to a structure up to now thought to be involved mainly in motor and cognitive functions, much less in emotional processes and even less in personality individual differences. PMID:22965823

Laricchiuta, Daniela; Petrosini, Laura; Piras, Fabrizio; Macci, Enrica; Cutuli, Debora; Chiapponi, Chiara; Cerasa, Antonio; Picerni, Eleonora; Caltagirone, Carlo; Girardi, Paolo; Tamorri, Stefano Maria; Spalletta, Gianfranco

2014-01-01

374

Qualitative and quantitative aspects of the microanatomy of the African elephant cerebellar cortex.  

PubMed

The current study provides a number of novel observations on the organization and structure of the cerebellar cortex of the African elephant by using a combination of basic neuroanatomical and immunohistochemical stains with Golgi and stereologic analysis. While the majority of our observations indicate that the cerebellar cortex of the African elephant is comparable to other mammalian species, several features were unique to the elephant. The three-layered organization of the cerebellar cortex, the neuronal types and some aspects of the expression of calcium-binding proteins were common to a broad range of mammalian species. The Lugaro neurons observed in the elephant were greatly enlarged in comparison to those of other large-brained mammals, suggesting a possible alteration in the processing of neural information in the elephant cerebellar cortex. Analysis of Golgi impregnations indicated that the dendritic complexity of the different interneuron types was higher in elephants than other mammals. Expression of parvalbumin in the parallel fibers and calbindin expressed in the stellate and basket cells also suggested changes in the elephant cerebellar neuronal circuitry. The stereologic analysis confirmed and extended previous observations by demonstrating that neuronal density is low in the elephant cerebellar cortex, providing for a larger volume fraction of the neuropil. With previous results indicating that the elephants have the largest relative cerebellar size amongst mammals, and one of the absolutely largest mammalian cerebella, the current observations suggest that the elephants have a greater volume of a potentially more complexly organized cerebellar cortex compared to other mammals. This quantitatively larger and more complex cerebellar cortex likely represents part of the neural machinery required to control the complex motor patterns involved in movement of the trunk and the production of infrasonic vocalizations. PMID:23296570

Maseko, Busisiwe C; Jacobs, Bob; Spocter, Muhammad A; Sherwood, Chet C; Hof, Patrick R; Manger, Paul R

2013-01-01

375

Cerebellar Transcranial Magnetic Stimulation: The Role of Coil Geometry and Tissue Depth?  

PubMed Central

Background While transcranial magnetic stimulation (TMS) coil geometry has important effects on the evoked magnetic field, no study has systematically examined how different coil designs affect the effectiveness of cerebellar stimulation. Hypothesis The depth of the cerebellar targets will limit efficiency. Angled coils designed to stimulate deeper tissue are more effective in eliciting cerebellar stimulation. Methods Experiment 1 examined basic input–output properties of the figure-of-eight, batwing and double-cone coils, assessed with stimulation of motor cortex. Experiment 2 assessed the ability of each coil to activate cerebellum, using cerebellar-brain inhibition (CBI). Experiment 3 mapped distances from the scalp to cerebellar and motor cortical targets in a sample of 100 subjects' structural magnetic resonance images. Results Experiment 1 showed batwing and double-cone coils have significantly lower resting motor thresholds, and recruitment curves with steeper slopes than the figure-of-eight coil. Experiment 2 showed the double-cone coil was the most efficient for eliciting CBI. The batwing coil induced CBI only at higher stimulus intensities. The figure-of-eight coil did not elicit reliable CBI. Experiment 3 confirmed that cerebellar tissue is significantly deeper than primary motor cortex tissue, and we provide a map of scalp-to-target distances. Conclusions The double-cone and batwing coils designed to stimulate deeper tissue can effectively stimulate cerebellar targets. The double-cone coil was found to be most effective. The depth map provides a guide to the accessible regions of the cerebellar volume. These results can guide coil selection and stimulation parameters when designing cerebellar TMS studies. PMID:24924734

Hardwick, Robert M.; Lesage, Elise; Miall, R. Chris

2014-01-01

376

Androgen Receptor and Calcitonin Gene-Related Peptide in Neurons of the Genitofemoral Nerve During Testicular Descent Induced with Human Chorionic Gonadotropin  

Microsoft Academic Search

Background. Low levels of circulating testosterone during testis descent cause cryptorchidism in humans and rats. Treatment with human chorionic gonadotrophin (hCG) induces testis descent by stimulating production of testosterone (T). Neurons of genitofemoral nerve (GFN), which innervate testicular gubernaculum, may play a role in testis descent.Methods. In the current study, putative correlations were made between T and GFN motor and

Rosa Mar??a Vigueras; Norma Moreno-Mendoza; Gabriela Reyes; Horacio Merchant-Larios

2003-01-01

377

Evidence against neurotransmitter mediation of sprouting in granuloprival cerebellar cultures.  

PubMed

Cerebellar cultures derived from neonatal mice undergo a remarkable sprouting of Purkinje cell recurrent axon collaterals after exposure for the 1st 5 days in vitro to cytosine arabinoside to destroy granule cells. Such cultures were simultaneously exposed to large concentrations of the putative neurotransmitters glutamate and GABA, with subsequent continued exposure to the amino acids until the time of fixation at 15 or 16 days in vitro. Axon collateral sprouting was not prevented by glutamate or GABA, suggesting the sprouting is not mediated by the relevant neurotransmitters, but is more likely due to an alteration or lack of development of some trophic interaction between granule cells and their target Purkinje cells. PMID:2857127

Seil, F J; Leiman, A L

1985-02-01

378

Memory trace and timing mechanism localized to cerebellar Purkinje cells.  

PubMed

The standard view of the mechanisms underlying learning is that they involve strengthening or weakening synaptic connections. Learned response timing is thought to combine such plasticity with temporally patterned inputs to the neuron. We show here that a cerebellar Purkinje cell in a ferret can learn to respond to a specific input with a temporal pattern of activity consisting of temporally specific increases and decreases in firing over hundreds of milliseconds without a temporally patterned input. Training Purkinje cells with direct stimulation of immediate afferents, the parallel fibers, and pharmacological blocking of interneurons shows that the timing mechanism is intrinsic to the cell itself. Purkinje cells can learn to respond not only with increased or decreased firing but also with an adaptively timed activity pattern. PMID:25267641

Johansson, Fredrik; Jirenhed, Dan-Anders; Rasmussen, Anders; Zucca, Riccardo; Hesslow, Germund

2014-10-14

379

Large cerebellar mass lesion: A rare intracranial manifestation of blastomycosis  

PubMed Central

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

Munich, Stephan A.; Johnson, Andrew K.; Ahuja, Sumeet K.; Venizelos, Alexander; Byrne, Richard W.

2013-01-01

380

Cerebellar contribution to linguistic processing efficiency revealed by focal damage.  

PubMed

The cerebellum's role in cognitive skills was examined in a child (L.C.) with focal injury to the left cerebellum. Initial symptoms included aphasia and dysarthria. At 3 and 9 months post-injury, clinical neuropsychological tests revealed persistent psychomotor slowing as well as deficits in executive functions. Further cognitive testing at 13 and 16 months post-injury demonstrated that L.C. processed information from both the linguistic and nonlinguistic domains more slowly than age-, grade- and sex-matched controls. Notably, her linguistic processing was more than twice as slow as that of her peers, whereas her nonlinguistic processing was only approximately 20% slower. Within each domain the degree of cognitive slowing was approximately the same across diverse tasks. These results are consistent with the hypothesis of a cerebellar contribution to cognitive processing, particularly the processing of linguistic information. PMID:9745238

Schatz, J; Hale, S; Myerson, J

1998-09-01

381

Upper limb cerebellar motor function in children with spina bifida  

PubMed Central

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

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

2011-01-01

382

Autosomal dominant cerebellar ataxias: clinical features, genetics, and pathogenesis.  

PubMed

Autosomal dominant cerebellar ataxias are hereditary neurodegenerative disorders that are known as spinocerebellar ataxias (SCA) in genetic nomenclature. In the pregenomic era, ataxias were some of the most poorly understood neurological disorders; the unravelling of their molecular basis enabled precise diagnosis in vivo and explained many clinical phenomena such as anticipation and variable phenotypes even within one family. However, the discovery of many ataxia genes and loci in the past decade threatens to cause more confusion than optimism among clinicians. Therefore, the provision of guidance for genetic testing according to clinical findings and frequencies of SCA subtypes in different ethnic groups is a major challenge. The identification of ataxia genes raises hope that essential pathogenetic mechanisms causing SCA will become more and more apparent. Elucidation of the pathogenesis of SCA hopefully will enable the development of rational therapies for this group of disorders, which currently can only be treated symptomatically. PMID:15099544

Schöls, Ludger; Bauer, Peter; Schmidt, Thorsten; Schulte, Thorsten; Riess, Olaf

2004-05-01

383

Hypothalamo-cerebellar and cerebello-hypothalamic pathways: a review and hypothesis concerning cerebellar circuits which may influence autonomic centers affective behavior.  

PubMed

Experimental data which have suggested the probability of connections between the cerebellum and hypothalamus are reviewed. Early studies relied mainly on physiological methods and, in general, concluded that such connections were multisynaptic being relayed via an undetermined number of synapses in the bulbar reticular formation. Recent studies, using horseradish peroxidase techniques, have identified direct connections between cerebellar nuclei and the hypothalamus and between several regions of hypothalamus and the cerebellar cortex. It is proposed that the cerebellum, by way of direct nucleo-hypothalamic projections and the resultant descending hypothalamic projections to visceral centers, has a variety of specific circuits through which it can directly influence autonomic centers. It is further noted that autonomic centers, as exemplified by hypothalamo-cerebellar projections, may have equally specific feedback loops to cerebellar cortex. Direct cerebello-hypothalamic projections and the subsequent diffuse pathways from hypothalamus into a number of forebrain areas may represent circuits responsible for the affective responses seen as a result of cerebellar ablation and/or stimulation. PMID:6093922

Haines, D E; Dietrichs, E; Sowa, T E

1984-01-01

384

Clinical and neuroanatomical predictors of cerebellar mutism syndrome.  

PubMed

Cerebellar mutism syndrome (CMS) is an important medical challenge in the management of pediatric posterior fossa brain tumors, because it occurs in a subset of children following tumor resection. A definitive clinical profile and neuroanatomical substrate associated with CMS remains unclear. We investigated the relationship between presurgical and clinical variables and the incidence of CMS, along with diffusion tensor imaging, to characterize the integrity of cerebello-thalamo-cerebral white matter pathways. Seventeen children with posterior fossa tumors and CMS, 34 children with posterior fossa tumors without CMS, and 28 healthy children were enrolled in this study. Bilateral cerebello-thalamo-cerebral pathways were delineated and segmented into anatomical regions. Mean integrity measures for each region were compared among children with CMS, children without CMS, and healthy children. Left-handedness, medulloblastoma histology, and larger tumor size distinguished between patients with CMS and patients without CMS (P < .04). Right cerebellar white matter within the cerebello-thalamo-cerebral pathway was compromised in children with CMS relative to children without CMS and healthy children (P < .02). We provide a potential schema for CMS risk among children treated for posterior fossa tumors. Left-handed children treated for medulloblastoma may be the most at risk for CMS, and unilateral, localized damage within the cerebello-thalamo-cerebral pathway at the level of the right cerebellum is implicated in the presentation of CMS. This disruption in communication between the right cerebellum and left frontal cortex may contribute to speech-language problems observed in children with CMS. Our findings may be relevant for surgical planning and speech-language therapy to mitigate symptoms of CMS. PMID:22952198

Law, Nicole; Greenberg, Mark; Bouffet, Eric; Taylor, Michael D; Laughlin, Suzanne; Strother, Douglas; Fryer, Christopher; McConnell, Dina; Hukin, Juliette; Kaise, Caelyn; Wang, Frank; Mabbott, Donald J

2012-10-01

385

Selective changes in cerebellar-cortical processing following motor training.  

PubMed

The aim of this study was to investigate the effect of varying stimulation rate and the effects of a repetitive typing task on the amplitude of somatosensory evoked potential (SEP) peaks thought to relate to cerebellar processing. SEPs (2,000 sweep averages) were recorded following median nerve stimulation at the wrist at frequencies of 2.47, 4.98, and 9.90 Hz from 12 subjects before and after a 20-min repetitive typing task. Typing and error rate were recorded 2-min pre- and post-typing task. Effect of stimulation rate was analysed with ANOVA followed by pairwise comparisons (paired t tests). Typing effects were analysed by performing two-tailed paired t tests. Increasing stimulation frequency significantly decreased the N30 SEP peak amplitude (p < 0.02). Both the 4.98 and 9.90 Hz rates lead to significantly smaller N30 peak amplitudes compared to the 2.47 Hz (p ? 0.01). The N24 amplitude significantly increased following the typing task for both 4.98 and 2.47 Hz (p ? 0.025). In contrast, there was a highly significant decrease (p < 0.001) in the N18 peak amplitude post-typing at all frequencies. Typing rate increased (p < 0.001) and error rate decreased (p < 0.05) following the typing task. The results suggest that the N24 SEP peak amplitude is best recorded at 4.98 Hz since the N30 amplitude decreases and no longer contaminates the N24 peak, making the N24 visible and easier to measure, while still enabling changes due to repetitive activity to be measured. The decrease in N18 amplitude along with an increase in N24 amplitude with no change in N20 amplitude may be explained by the intervention reducing inhibition at the level of the cuneate nucleus and/or interior olives leading to alterations in cerebellar-cortical processing. PMID:24065291

Haavik, H; Murphy, B A

2013-12-01

386

Encoding of whisker input by cerebellar Purkinje cells  

PubMed Central

The cerebellar cortex is crucial for sensorimotor integration. Sensorimotor inputs converge on cerebellar Purkinje cells via two afferent pathways: the climbing fibre pathway triggering complex spikes, and the mossy fibre–parallel fibre pathway, modulating the simple spike activities of Purkinje cells. We used, for the first time, the mouse whisker system as a model system to study the encoding of somatosensory input by Purkinje cells. We show that most Purkinje cells in ipsilateral crus 1 and crus 2 of awake mice respond to whisker stimulation with complex spike and/or simple spike responses. Single-whisker stimulation in anaesthetised mice revealed that the receptive fields of complex spike and simple spike responses were strikingly different. Complex spike responses, which proved to be sensitive to the amplitude, speed and direction of whisker movement, were evoked by only one or a few whiskers. Simple spike responses, which were not affected by the direction of movement, could be evoked by many individual whiskers. The receptive fields of Purkinje cells were largely intermingled, and we suggest that this facilitates the rapid integration of sensory inputs from different sources. Furthermore, we describe that individual Purkinje cells, at least under anaesthesia, may be bound in two functional ensembles based on the receptive fields and the synchrony of the complex spike and simple spike responses. The ‘complex spike ensembles’ were oriented in the sagittal plane, following the anatomical organization of the climbing fibres, while the ‘simple spike ensembles’ were oriented in the transversal plane, as are the beams of parallel fibres. PMID:20724365

Bosman, Laurens W J; Koekkoek, Sebastiaan K E; Shapiro, Joel; Rijken, Bianca F M; Zandstra, Froukje; van der Ende, Barry; Owens, Cullen B; Potters, Jan-Willem; de Gruijl, Jornt R; Ruigrok, Tom J H; De Zeeuw, Chris I

2010-01-01

387

A PET study of cerebellar metabolism in normal and abnormal states  

SciTech Connect

The authors studied cerebellar metabolism under varying conditions of sensory stimulation. Cerebellar glucose consumption was measured by positron emission scanning and 18F-fluorodeoxyglucose in 64 subjects. Cerebellar metabolism relative to the whole brain (CM), and the asymmetry of metabolism between the cerebellar hemispheres (CA) was determined. The lowest CM occurred with maximal sensory deprivation, eyes and ears closed, (CM=96%, n=6). CM increased nonsignificantly with visual stimulation (CM=99%,n=17) and was highest for auditory stimulation (CM=104%,n=10,p<.05). CA was unaffected by sensory input. Under ambient conditions the CM values were 101%, 113% and 135% respectively for young controls (n=9, age=22), old controls (n=8, age=61) and Alzheimer patients (SDAT, n=14, age=69). This difference was significant for SDAT vs young and old controls and was nearly significant for young vs old controls.

Kushner, M.; Alavi, A.; Chawluk, J.; Silver, F.; Dann, R.; Rosen, M.; Reivich, M.

1985-05-01

388

Hochreiter, Sepp Copy Number Aberrations Affecting the Developing Cerebellar Vermis are Associated  

E-print Network

Cerebellar Vermis are Associated with Autism Spectrum Disorders Sepp Hochreiter, Djork-Arné Clevert Motivation: We investigated neurodevelopmental dysfunctions in autism spectrum disorders (ASD histochemistry data from the developing mouse brain. In contrast to the original association studies, we

Hochreiter, Sepp

389

Local flow management/profile descent algorithm. Fuel-efficient, time-controlled profiles for the NASA TSRV airplane  

NASA Technical Reports Server (NTRS)

The Local Flow Management/Profile Descent (LFM/PD) algorithm designed for the NASA Transport System Research Vehicle program is described. The algorithm provides fuel-efficient altitude and airspeed profiles consistent with ATC restrictions in a time-based metering environment over a fixed ground track. The model design constraints include accommodation of both published profile descent procedures and unpublished profile descents, incorporation of fuel efficiency as a flight profile criterion, operation within the performance capabilities of the Boeing 737-100 airplane with JT8D-7 engines, and conformity to standard air traffic navigation and control procedures. Holding and path stretching capabilities are included for long delay situations.

Groce, J. L.; Izumi, K. H.; Markham, C. H.; Schwab, R. W.; Thompson, J. L.

1986-01-01

390

Cerebellar patients demonstrate preserved implicit knowledge of association strengths in musical sequences  

Microsoft Academic Search

Recent findings suggest the involvement of the cerebellum in perceptual and cognitive tasks. Our study investigated whether cerebellar patients show musical priming based on implicit knowledge of tonal-harmonic music. Participants performed speeded phoneme identification on sung target chords, which were either related or less-related to prime contexts in terms of the tonal-harmonic system. As groups, both cerebellar patients and age-matched

Barbara Tillmann; Timothy Justus; Emmanuel Bigand

2008-01-01

391

Evidence for a GABA-mediated cerebellar inhibition of the inferior olive in the cat  

Microsoft Academic Search

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

G. Andersson; M. Garwicz; G. Hesslow

1988-01-01

392

Treatment of Ataxia in Cortical Cerebellar Atrophy with the GABAergic Drug Gabapentin  

Microsoft Academic Search

The aim of this work was to investigate the efficacy of the GABAergic drug gabapentin in the treatment of the cerebellar signs caused by cortical cerebellar atrophy (CCA). Ten patients with CCA received gabapentin in single doses of 400 mg in an open-label study; thereafter, daily administration of 900–1,600 mg of gabapentin was continued during at least 4 weeks. An

José Gazulla; José M. Errea; Isabel Benavente; Carlos J. Tordesillas

2004-01-01

393

Structural and Functional Magnetic Resonance Imaging of the Human Cerebellar Nuclei  

Microsoft Academic Search

The present review focuses on recent developments in structural and functional magnetic resonance imaging (MRI) of the deep\\u000a cerebellar nuclei (DCN), the main output structure of the cerebellum. The high iron content in the DCN allows for their visibility\\u000a in T2*-weighted images. Spatial resolution has improved allowing the identification of DCN in individual cerebellar patients\\u000a and healthy subjects. Based on

Michael Küper; Markus Thürling; Stefan Maderwald; Mark E. Ladd; Dagmar Timmann

394

Anterior cingulate and cerebellar GABA and Glu correlations measured by 1H J-difference spectroscopy  

Microsoft Academic Search

Gamma-aminobutyric acid (GABA) and glutamate (Glu) levels, normalized to total creatine (tCr), were measured in the anterior cingulate and cerebellar vermis in healthy adults (n=19, age=24.6±6.4 years) using 1H MRS at 3 T, and metabolite correlations across regions and subjects were determined. Mean anterior cingulate and cerebellar GABA\\/tCr ratios were 0.31 (0.08) and 0.23 (0.06), respectively, while corresponding Glu levels

Kevin W. Waddell; Parham Zanjanipour; Subechhya Pradhan; Lei Xu; Edward B. Welch; James M. Joers; Peter R. Martin; Malcolm J. Avison; John C. Gore

2011-01-01

395

Cilia proteins control cerebellar morphogenesis by promoting expansion of the granule progenitor pool.  

PubMed

Although human congenital cerebellar malformations are common, their molecular and developmental basis is still poorly understood. Recently, cilia-related gene deficiencies have been implicated in several congenital disorders that exhibit cerebellar abnormalities such as Joubert syndrome, Meckel-Gruber syndrome, Bardet-Biedl syndrome, and Orofaciodigital syndrome. The association of cilia gene mutations with these syndromes suggests that cilia may be important for cerebellar development, but the nature of cilia involvement has not been elucidated. To assess the importance of cilia-related proteins during cerebellar development, we studied the effects of CNS-specific inactivation of two mouse genes whose protein products are critical for cilia formation and maintenance, IFT88, (also known as polaris or Tg737), which encodes intraflagellar transport 88 homolog, and Kif3a, which encodes kinesin family member 3a. We showed that loss of either of these genes caused severe cerebellar hypoplasia and foliation abnormalities, primarily attributable to a failure of expansion of the neonatal granule cell progenitor population. In addition, granule cell progenitor proliferation was sensitive to partial loss of IFT function in a hypomorphic mutant of IFT88 (IFT88(orpk)), an effect that was modified by genetic background. IFT88 and Kif3a were not required for the specification and differentiation of most other cerebellar cell types, including Purkinje cells. Together, our observations constitute the first demonstration that cilia proteins are essential for normal cerebellar development and suggest that granule cell proliferation defects may be central to the cerebellar pathology in human cilia-related disorders. PMID:17804638

Chizhikov, Victor V; Davenport, James; Zhang, Qihong; Shih, Evelyn Kim; Cabello, Olga A; Fuchs, Jannon L; Yoder, Bradley K; Millen, Kathleen J

2007-09-01

396

Cerebellar Transcranial Direct Current Stimulation Impairs the Practice-dependent Proficiency Increase in Working Memory  

Microsoft Academic Search

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

R. Ferrucci; S. Marceglia; M. Vergari; F. Cogiamanian; S. Mrakic-sposta; F. Mameli; S. Zago; S. Barbieri; A. Priori

2008-01-01

397

Spontaneous poisoning by Solanum subinerme Jack as a cause of cerebellar cortical degeneration in cattle.  

PubMed

The present work reports cerebellar degeneration in cattle associated with the ingestion of Solanum subinerme in northern Brazil. The main clinical signs were periodic crises with loss of balance, falls, opisthotonus, and nystagmus. The histological lesions consisted of diffuse vacuolation of the perikaryon of the Purkinje neurons, followed by the loss of these cells and their substitution by Bergman glia. It is concluded that S. subinerme is another species of Solanum that causes cerebellar degeneration in cattle. PMID:24561122

Lima, Everton Ferreira; Riet-Correa, Franklin; de Medeiros, Rosane Maria Trindade

2014-05-01

398

Deregulated FGF and homeotic gene expression underlies cerebellar vermis hypoplasia in CHARGE syndrome  

PubMed Central

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

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

399

Cerebellar sensory processing alterations impact motor cortical plasticity in Parkinson's disease: clues from dyskinetic patients.  

PubMed

The plasticity of primary motor cortex (M1) in patients with Parkinson's disease (PD) and levodopa-induced dyskinesias (LIDs) is severely impaired. We recently reported in young healthy subjects that inhibitory cerebellar stimulation enhanced the sensorimotor plasticity of M1 that was induced by paired associative stimulation (PAS). This study demonstrates that the deficient sensorimotor M1 plasticity in 16 patients with LIDs could be reinstated by a single session of real inhibitory cerebellar stimulation but not sham stimulation. This was evident only when a sensory component was involved in the induction of plasticity, indicating that cerebellar sensory processing function is involved in the resurgence of M1 plasticity. The benefit of inhibitory cerebellar stimulation on LIDs is known. To explore whether this benefit is linked to the restoration of sensorimotor plasticity of M1, we conducted an additional study looking at changes in LIDs and PAS-induced plasticity after 10 sessions of either bilateral, real inhibitory cerebellar stimulation or sham stimulation. Only real and not sham stimulation had an antidyskinetic effect and it was paralleled by a resurgence in the sensorimotor plasticity of M1. These results suggest that alterations in cerebellar sensory processing function, occurring secondary to abnormal basal ganglia signals reaching it, may be an important element contributing to the maladaptive sensorimotor plasticity of M1 and the emergence of abnormal involuntary movements. PMID:23535177

Kishore, Asha; Popa, Traian; Balachandran, Ammu; Chandran, Shyambabu; Pradeep, Salini; Backer, Febina; Krishnan, Syam; Meunier, Sabine

2014-08-01

400

Minimum-fuel turning climbout and descent guidance of transport jets  

NASA Technical Reports Server (NTRS)

The complete flightpath optimization problem for minimum fuel consumption from takeoff to landing including the initial and final turns from and to the runway heading is solved. However, only the initial and final segments which contain the turns are treated, since the straight-line climbout, cruise, and descent problems have already been solved. The paths are derived by generating fields of extremals, using the necessary conditions of optimal control together with singular arcs and state constraints. Results show that the speed profiles for straight flight and turning flight are essentially identical except for the final horizontal accelerating or decelerating turns. The optimal turns require no abrupt maneuvers, and an approximation of the optimal turns could be easily integrated with present straight-line climb-cruise-descent fuel-optimization algorithms. Climbout at the optimal IAS rather than the 250-knot terminal-area speed limit would save 36 lb of fuel for the 727-100 aircraft.

Neuman, F.; Kreindler, E.

1983-01-01

401

Assessment of the Mars Science Laboratory Entry, Descent, and Landing Simulation  

NASA Technical Reports Server (NTRS)

On August 5, 2012, the Mars Science Laboratory rover, Curiosity, successfully landed inside Gale Crater. This landing was only the seventh successful landing and fourth rover to be delivered to Mars. Weighing nearly one metric ton, Curiosity is the largest and most complex rover ever sent to investigate another planet. Safely landing such a large payload required an innovative Entry, Descent, and Landing system, which included the first guided entry at Mars, the largest supersonic parachute ever flown at Mars, and a novel and untested Sky Crane landing system. A complete, end-to-end, six degree-of-freedom, multi-body computer simulation of the Mars Science Laboratory Entry, Descent, and Landing sequence was developed at the NASA Langley Research Center. In-flight data gathered during the successful landing is compared to pre-flight statistical distributions, predicted by the simulation. These comparisons provide insight into both the accuracy of the simulation and the overall performance of the vehicle.

Way, David W.; Davis, J. L.; Shidner, Jeremy D.

2013-01-01

402

Preliminary Assessment of the Mars Science Laboratory Entry, Descent, and Landing Simulation  

NASA Technical Reports Server (NTRS)

On August 5, 2012, the Mars Science Laboratory rover, Curiosity, successfully landed inside Gale Crater. This landing was only the seventh successful landing and fourth rover to be delivered to Mars. Weighing nearly one metric ton, Curiosity is the largest and most complex rover ever sent to investigate another planet. Safely landing such a large payload required an innovative Entry, Descent, and Landing system, which included the first guided entry at Mars, the largest supersonic parachute ever flown at Mars, and a novel and untested Sky Crane landing system. A complete, end-to-end, six degree-of-freedom, multibody computer simulation of the Mars Science Laboratory Entry, Descent, and Landing sequence was developed at the NASA Langley Research Center. In-flight data gathered during the successful landing is compared to pre-flight statistical distributions, predicted by the simulation. These comparisons provide insight into both the accuracy of the simulation and the overall performance of the vehicle.

Way, David W.

2013-01-01

403

Capture Conditions for Merging Trajectory Segments to Model Realistic Aircraft Descents  

NASA Technical Reports Server (NTRS)

A typical commercial aircraft trajectory consists of a series of flight segments. An aircraft switches from one segment to another when certain specified variables reach their desired values. Trajectory synthesis for air traffic control automation must be consistent with practical pilot procedures. We examine capture conditions for merging trajectory segments to model commercial aircraft descent in trajectory synthesis. These conditions translate into bounds on measurements of atmospheric wind, pressure, and temperature. They also define ranges of thrust and drag feasible for a descent trajectory. Capture conditions are derived for the Center-TRACON Automation System developed at NASA Ames Research Center for automated air traffic control. Various uses of capture conditions are discussed. A Boeing 727-200 aircraft is used to provide numerical examples of capture conditions.

Zhao, Yiyuan; Slattery, Rhonda A.

1996-01-01

404

Post2 End-to-End Descent and Landing Simulation for ALHAT Design Analysis Cycle 2  

NASA Technical Reports Server (NTRS)

The ALHAT project is an agency-level program involving NASA centers, academia, and industry, with a primary goal to develop a safe, autonomous, precision-landing system for robotic and crew-piloted lunar and planetary descent vehicles. POST2 is used as the 6DOF descent and landing trajectory simulation for determining integrated system performance of ALHAT landing-system models and lunar environment models. This paper presents updates in the development of the ALHAT POST2 simulation, as well as preliminary system performance analysis for ALDAC-2 used for the testing and assessment of ALHAT system models. The ALDAC-2 POST2 Monte Carlo simulation results have been generated and focus on HRN model performance with the fully integrated system, as well performance improvements of AGNC and TSAR model since the previous design analysis cycle

Davis, Jody L.; Striepe, Scott A.; Maddock, Robert W.; Johnson, Andrew E.; Paschall, Stephen C., II

2010-01-01

405

Multibody Modeling and Simulation for the Mars Phoenix Lander Entry, Descent and Landing  

NASA Technical Reports Server (NTRS)

A multi-body flight simulation for the Phoenix Mars Lander has been developed that includes high fidelity six degree-of-freedom rigid-body models for the parachute and lander system. The simulation provides attitude and rate history predictions of all bodies throughout the flight, as well as loads on each of the connecting lines. In so doing, a realistic behavior of the descending parachute/lander system dynamics can be simulated that allows assessment of the Phoenix descent performance and identification of potential sensitivities for landing. This simulation provides a complete end-to-end capability of modeling the entire entry, descent, and landing sequence for the mission. Time histories of the parachute and lander aerodynamic angles are presented. The response of the lander system to various wind models and wind shears is shown to be acceptable. Monte Carlo simulation results are also presented.

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

2008-01-01

406

Natural Gradient Descent for Training Stochastic Complex-Valued Neural Networks  

Microsoft Academic Search

In this paper, the natural gradient descent method for the multilayer stochastic complex-valued neural networks is considered, and the natural gradient is given for a single stochastic complex-valued neuron as an example. Since the space of the learnable parameters of stochastic complex-valued neural networks is not the Euclidean space but a curved manifold, the complex-valued natural gradient method is expected

Tohru Nitta

2014-01-01

407

Entry, Descent, and Landing Aerothermodynamics: NASA Langley Experimental Capabilities and Contributions  

NASA Technical Reports Server (NTRS)

A review is presented of recent research, development, testing and evaluation activities related to entry, descent and landing that have been conducted at the NASA Langley Research Center. An overview of the test facilities, model development and fabrication capabilities, and instrumentation and measurement techniques employed in this work is provided. Contributions to hypersonic/supersonic flight and planetary exploration programs are detailed, as are fundamental research and development activities.

Hollis, Brian R.; Berger, Karen T.; Berry, Scott A.; Bruckmann, Gregory J.; Buck, Gregory M.; DiFulvio, Michael; Horvath, Thomas J.; Liechty, Derek S.; Merski, N. Ronald; Murphy, Kelly J.; Rufer, Shann J.; Schoenenberger, Mark

2014-01-01

408

Aerodynamic design of a descent vehicle in the Martian atmosphere under the exomars project  

NASA Astrophysics Data System (ADS)

The paper considers mathematical support for calculation of the aerodynamics and flight trajectory of descent vehicles (DV) during entry into the Martian atmosphere. The study of aerodynamics of a segmental and conical DV is given under various reentry conditions. The paper presents comparison of computational results of the aerodynamic properties of the DV of the ExoMars project with wind tunnel test data of DV models.

Golomazov, M. M.; Finchenko, V. S.

2014-12-01

409

STS-35 Pilot Gardner with descent checklist on OV-102's forward flight deck  

NASA Technical Reports Server (NTRS)

STS-35 Pilot Guy S. Gardner, wearing his launch and entry suit (LES), reviews descent checklist while at the pilots station on the forward flight deck of Columbia, Orbiter Vehicle (OV) 102. Crewmembers are conducting procedures related to the final stages of the mission and the landing sequence. Silhouetted in forward windows W4 and W5 are the head up display (HUD), flight mirror assembly, and a drinking water bag with straw.

1990-01-01

410

Chang’E-2 satellite asymmetric-descent orbit control technology  

Microsoft Academic Search

To accomplish high-resolution imaging of the preselected landing area, it was necessary for the Chang’E-2 mission to perform\\u000a orbital maneuvering on the far side of the moon to meet the conditional height requirement of the imaging area. Engine shutdown\\u000a would be executed invisibly on the back side of the moon if the descent maneuver mode opposite to the target perilune

JianLiang Zhou; Yong Liu; DeYun Peng; FengCai Zhao

2011-01-01

411

Strong refraction near the Venus surface - Effects observed by descent probes  

NASA Technical Reports Server (NTRS)

The telemetry signals from Pioneer Venus probes indicated the strong downward refraction of radio waves. As the probes descended, the strength of the direct signal decreased because of absorption and refractive defocusing. During the last 30 km of descent there was a second measured component in addition to the direct signal. Strong atmospheric reaction is important in strengthening echoes that are scattered toward the earth. Such surface-reflected signals are good indicators of horizontal winds.

Croft, T. A.

1982-01-01

412

Factors Associated with Overweight and Obesity among Children of Mexican Descent: Results of a Binational Study  

Microsoft Academic Search

The prevalence of childhood obesity is high among young children of Mexican origin in the United States, however, the determinants\\u000a are poorly understood. We conducted a binational study with a sample from California (CA) and Mexico (MX), to identify and\\u000a compare the most important factors associated with overweight and obesity among children of Mexican descent. Significantly\\u000a more children were classified

Lisa G. Rosas; Sylvia Guendelman; Kim Harley; Lia C. H. Fernald; Lynnette Neufeld; Fabiola Mejia; Brenda Eskenazi

2011-01-01

413

Segmented assimilation theory and perinatal health disparities among women of Mexican descent  

Microsoft Academic Search

A higher prevalence of infant low birth weight (<2500g) has been observed among more acculturated mothers of Mexican descent living in the U.S. when compared to their less acculturated counterparts. Tests of the “acculturation hypothesis” have established that disparities in certain risks for low birth weight exist between subgroups of women of Mexican-origin. However, disparities observed by neighborhood of residence

Michelle A. Johnson; Kristen S. Marchi

2009-01-01

414

Biological effects of fuel and exhaust components from spacecraft descent engines employing hydrazine  

NASA Technical Reports Server (NTRS)

The effect of the products of the Viking terminal descent engine fuel upon possible extraterrestrial life at the Martian landing site is examined. The effects of the engine exhaust, the hydrazine fuel, and the breakdown products of the latter on terrestrial microorganisms have been studied. The results indicate that the gaseous exhaust products would probably not be hazardous to microorganisms, but that liquid hydrazine would be lethal.

Lehwalt, M. E.; Woeller, F. H.; Oyama, V. I.

1973-01-01

415

Aerosol and Cloud Properties at the Huygens Entry Site as Derived from the Descent Imager/Spectral  

NASA Technical Reports Server (NTRS)

The Huygens Probe descended through Titan s atmosphere on January 14, 2005. The Descent Imager/Spectral Radiometer (DISR) instrument made optical measurements which constrain the nature and vertical distribution and of the aerosols in the atmosphere.

Doose, L. R.; Engel, S.; Tomasko, M. G.; Dafoe, L. E.; West, R.; Lemmon, M.

2005-01-01

416

25 CFR 18.104 - May a tribe include provisions in its tribal probate code regarding the distribution and descent...  

...a tribe include provisions in its tribal probate code regarding the distribution and descent of trust...DEPARTMENT OF THE INTERIOR PROBATE TRIBAL PROBATE CODES Approval of Tribal Probate Codes § 18.104 May a tribe include provisions...

2014-04-01

417

25 CFR 18.104 - May a tribe include provisions in its tribal probate code regarding the distribution and descent...  

Code of Federal Regulations, 2012 CFR

...a tribe include provisions in its tribal probate code regarding the distribution and descent of trust...DEPARTMENT OF THE INTERIOR PROBATE TRIBAL PROBATE CODES Approval of Tribal Probate Codes § 18.104 May a tribe include provisions...

2012-04-01

418

25 CFR 18.104 - May a tribe include provisions in its tribal probate code regarding the distribution and descent...  

Code of Federal Regulations, 2013 CFR

...a tribe include provisions in its tribal probate code regarding the distribution and descent of trust...DEPARTMENT OF THE INTERIOR PROBATE TRIBAL PROBATE CODES Approval of Tribal Probate Codes § 18.104 May a tribe include provisions...

2013-04-01

419

25 CFR 18.104 - May a tribe include provisions in its tribal probate code regarding the distribution and descent...  

Code of Federal Regulations, 2011 CFR

...a tribe include provisions in its tribal probate code regarding the distribution and descent of trust...DEPARTMENT OF THE INTERIOR PROBATE TRIBAL PROBATE CODES Approval of Tribal Probate Codes § 18.104 May a tribe include provisions...

2011-04-01

420

25 CFR 18.104 - May a tribe include provisions in its tribal probate code regarding the distribution and descent...  

Code of Federal Regulations, 2010 CFR

...a tribe include provisions in its tribal probate code regarding the distribution and descent of trust...DEPARTMENT OF THE INTERIOR PROBATE TRIBAL PROBATE CODES Approval of Tribal Probate Codes § 18.104 May a tribe include provisions...

2010-04-01

421

A Tribute to Italian Physiologists of Jewish Descent Evicted During the Persecution Ordered by the Fascist Regime in 1938  

NSDL National Science Digital Library

The present report commemorates the persecution of five renown Italian physiologists of Jewish descent that lost their chairs in medical schools because of the anti-semitic policies of the fascist regime.

Ermanno Manni (Catholic University Institute of Human Physiology, School of Medicine)

2007-06-01

422

Review of studies on metabolic genes and cancer in populations of African descent  

PubMed Central

Genetic polymorphisms described for a number of enzymes involved in the metabolism of tobacco carcinogens and alcohol have been linked to increase cancer risk. Racial disparities in cancer between Whites and populations of African descent are well documented. In addition to differences in access to health care, both environment and genetic factors and their interaction may contribute to the increased cancer risk in minority populations. We reviewed the literature to identify case-control studies that included subjects of African descent. Meta analyses investigating the association of genetic polymorphisms in tobacco metabolic genes and cancer were performed. While several genes and cancers have been studied, only one or two studies per gene for each cancer site have been published, with the exception of breast (CYP1A1 and CYP1B1), lung (GSTM1, CYP1A1, and NQO1) and prostate (CYP3A4 A293G and CYP17). Marginal statistically significant associations were observed for CYP3A4 A293G and CYP17 5'UTR polymorphisms and prostate cancer. Our findings support the need for additional genetic association studies of breast, prostate and lung cancers that include a larger number of minority participants. Since incidence and mortality rates for these cancers rank highest among populations of African descent concentrated research in these areas are warranted. PMID:20027111

Ragin, Camille C.; Langevin, Scott; Rubin, Scott; Taioli, Emanuela

2010-01-01

423

Content validation of a clinical assessment instrument for stair ascent and descent in individuals with hemiparesis  

PubMed Central

Background: Among the current instruments used to assess stair ambulation, none were observed that specifically evaluated the quality of movement or biomechanical strategies adopted by stroke patients. Objective: To evaluate the content validity of a clinical instrument designed to identify the qualitative and kinematic characteristics and strategies adopted by stroke patients during stair ascent and descent. Method: The first developed version, which comprised 80 items, had its content evaluated by an expert panel, which was composed of 9 well-known national and international professionals who are involved in stroke rehabilitation. The content validity index (CVI) and modified Kappa coefficients were employed for the statistical analyses. The items that demonstrated a CVI?0.80 and Kappa?0.75 were considered valid. Results: The content validation was performed in three stages. The final version of the instrument consisted of 38 items, which were divided into descriptive (8 items), a General Characteristics Domain (16 items) and adopted strategies (14 items) during stair ascent and descent. The total scores ranged from zero to 70 and zero to 74 for ascent and descent, respectively. Lower scores corresponded with better performance. Conclusion: Despite the satisfactory results obtained during the process of content validation, other psychometric properties of the instrument are necessary and must be evaluated. PMID:25054384

Natalio, Mavie A.; Faria, Christina D. C. M.; Teixeira-Salmela, Luci F.; Michaelsen, Stella M.

2014-01-01

424

Additive genetic variation in schizophrenia risk is shared by populations of African and European descent.  

PubMed

To investigate the extent to which the proportion of schizophrenia's additive genetic variation tagged by SNPs is shared by populations of European and African descent, we analyzed the largest combined African descent (AD [n = 2,142]) and European descent (ED [n = 4,990]) schizophrenia case-control genome-wide association study (GWAS) data set available, the Molecular Genetics of Schizophrenia (MGS) data set. We show how a method that uses genomic similarities at measured SNPs to estimate the additive genetic correlation (SNP correlation [SNP-rg]) between traits can be extended to estimate SNP-rg for the same trait between ethnicities. We estimated SNP-rg for schizophrenia between the MGS ED and MGS AD samples to be 0.66 (SE = 0.23), which is significantly different from 0 (p(SNP-rg = 0) = 0.0003), but not 1 (p(SNP-rg = 1) = 0.26). We re-estimated SNP-rg between an independent ED data set (n = 6,665) and the MGS AD sample to be 0.61 (SE = 0.21, p(SNP-rg = 0) = 0.0003, p(SNP-rg = 1) = 0.16). These results suggest that many schizophrenia risk alleles are shared across ethnic groups and predate African-European divergence. PMID:23954163

de Candia, Teresa R; Lee, S Hong; Yang, Jian; Browning, Brian L; Gejman, Pablo V; Levinson, Douglas F; Mowry, Bryan J; Hewitt, John K; Goddard, Michael E; O'Donovan, Michael C; Purcell, Shaun M; Posthuma, Danielle; Visscher, Peter M; Wray, Naomi R; Keller, Matthew C

2013-09-01

425

Mars Science Laboratory Entry, Descent, and Landing Trajectory and Atmosphere Reconstruction  

NASA Technical Reports Server (NTRS)

On August 5th 2012, The Mars Science Laboratory entry vehicle successfully entered Mars atmosphere and landed the Curiosity rover on its surface. A Kalman filter approach has been implemented to reconstruct the entry, descent, and landing trajectory based on all available data. The data sources considered in the Kalman filtering approach include the inertial measurement unit accelerations and angular rates, the terrain descent sensor, the measured landing site, orbit determination solutions for the initial conditions, and a new set of instrumentation for planetary entry reconstruction consisting of forebody pressure sensors, known as the Mars Entry Atmospheric Data System. These pressure measurements are unique for planetary entry, descent, and landing reconstruction as they enable a reconstruction of the freestream atmospheric conditions without any prior assumptions being made on the vehicle aerodynamics. Moreover, the processing of these pressure measurements in the Kalman filter approach enables the identification of atmospheric winds, which has not been accomplished in past planetary entry reconstructions. This separation of atmosphere and aerodynamics allows for aerodynamic model reconciliation and uncertainty quantification, which directly impacts future missions. This paper describes the mathematical formulation of the Kalman filtering approach, a summary of data sources and preprocessing activities, and results of the reconstruction.

Karlgaard, Christopher D.; Kutty, Prasad; Schoenenberer, Mark; Shidner, Jeremy D.

2013-01-01

426

Additive Genetic Variation in Schizophrenia Risk Is Shared by Populations of African and European Descent  

PubMed Central

To investigate the extent to which the proportion of schizophrenia’s additive genetic variation tagged by SNPs is shared by populations of European and African descent, we analyzed the largest combined African descent (AD [n = 2,142]) and European descent (ED [n = 4,990]) schizophrenia case-control genome-wide association study (GWAS) data set available, the Molecular Genetics of Schizophrenia (MGS) data set. We show how a method that uses genomic similarities at measured SNPs to estimate the additive genetic correlation (SNP correlation [SNP-rg]) between traits can be extended to estimate SNP-rg for the same trait between ethnicities. We estimated SNP-rg for schizophrenia between the MGS ED and MGS AD samples to be 0.66 (SE = 0.23), which is significantly different from 0 (p(SNP-rg = 0) = 0.0003), but not 1 (p(SNP-rg = 1) = 0.26). We re-estimated SNP-rg between an independent ED data set (n = 6,665) and the MGS AD sample to be 0.61 (SE = 0.21, p(SNP-rg = 0) = 0.0003, p(SNP-rg = 1) = 0.16). These results suggest that many schizophrenia risk alleles are shared across ethnic groups and predate African-European divergence. PMID:23954163

de Candia, Teresa R.; Lee, S. Hong; Yang, Jian; Browning, Brian L.; Gejman, Pablo V.; Levinson, Douglas F.; Mowry, Bryan J.; Hewitt, John K.; Goddard, Michael E.; O'Donovan, Michael C.; Purcell, Shaun M.; Posthuma, Danielle; Visscher, Peter M.; Wray, Naomi R.; Keller, Matthew C.

2013-01-01

427

Flight-Deck Strategies and Outcomes When Flying Schedule-Matching Descents  

NASA Technical Reports Server (NTRS)

Recent studies at NASA Ames Research Center have investigated the development and use of ground-based (air traffic controller) tools to manage and schedule air traffic in future terminal airspace. An exploratory study was undertaken to investigate the impacts that such tools (and concepts) could have on the flight-deck. Ten Boeing 747-400 crews flew eight optimized profile descents in the Los Angeles terminal airspace, while receiving scripted current day and futuristic speed clearances, to ascertain their ability to fly schedulematching descents without prior training. Although the study was exploratory in nature, four variables were manipulated: route constraints, winds, speed changes, and clearance phraseology. Despite flying the same scenarios with the same events and timing, there were significant differences in the time it took crews to fly the approaches. This variation is the product of a number of factors but highlights potential difficulties for scheduling tools that would have to accommodate this amount of natural variation in descent times. The focus of this paper is the examination of the crews' aircraft management strategies and outcomes. This includes potentially problematic human-automation interaction issues that may negatively impact arrival times, speed and altitude constraint compliance, and energy management efficiency.

Kaneshige, John T.; Sharma, Shivanjli; Martin Lynne; Lozito, Sandra; Dulchinos, Victoria

2013-01-01

428

First Results from the Descent Imager/Spectral Radiometer (DISR) Experiment on the Huygens Entry Probe of Titan  

NASA Technical Reports Server (NTRS)

The Cassini-Huygens mission was launched on October 15, 1997, and arrived in Orbit around Saturn in July, 2004. The Huygens Probe was released from the Cassini Orbiter on December 24, 2004 and entered Titan s atmosphere on January 14, 2005. Here we give the first results from the Descent Imager/Spectral Radiometer (DISR) instrument aboard the Huygens Probe during its descent into the atmosphere of Titan. Measurements were made by several different optical systems and sensors.

Tomasko, M. G.; Doose, L. R.; Rizk, B.; Smith, P.; See, C.; Bushroe, M.; McFarlane, L.; Engel, S.; Eibl, A.; Karkoschka, E.

2005-01-01

429

Gubernacular fibroblasts express the androgen receptor during testis descent in cryptorchid rats treated with human chorionic gonadotrophin  

Microsoft Academic Search

Cryptorchidism was provoked in 3 day old rats treated with 17-?-estradiol over 30 days to identify the cells that express the androgen receptor (AR) during experimental testis descent in the gubernaculum. In one group of animals, testis descent was induced with human chorionic gonadotrophin (hCG) applied daily for 5 or 10 days. A correlative study using a testosterone radioimmunoassay with electron microscopy and

Rosa Maria Vigueras; Gabriela Reyes; Norma Moreno-Mendoza; Horacio Merchant-Larios

2004-01-01

430

Calcium clearance and its energy requirements in cerebellar neurons  

PubMed Central

Quick cytosolic calcium clearance is essential for the effective modulation of various cellular functions. An excess of cytosolic calcium after influx is largely removed via ATP-dependent mechanisms located in the plasma membrane and the endoplasmic reticulum. Therefore, calcium clearance depends critically on the adequate supply of ATP, which may come from either glycolysis or mitochondria, or both. However, it presently remains unknown the degree to which individual ATP generating pathways - glycolysis and mitochondria power ATP-dependent calcium as well as other vital ion clearance mechanisms in neurons. In this study, we explored the relationship between the energy generating pathways and ion clearance mechanisms in neurons by characterizing the effects of glycolytic and mitochondrial inhibitors of ATP synthesis on calcium clearance kinetics in the soma, dendrites and spines. Stimulation of cultured cerebellar granule cells by brief pulses of 60 mM potassium ACSF, and electrical stimulation of purkinje cells in acutely prepared slices led to a transient calcium influx, whose clearance was largely mediated by the plasma membrane Ca2+-ATPase pump. Inhibition of glycolysis by deoxyglucose or iodoacetic acid resulted in a marked slowing in calcium clearance in the soma, dendrites, and spines with the spines affected the most. However, inhibition of the mitochondrial citric acid cycle with fluoroacetate and arsenite, or mitochondrial ATP-synthase with oligomycin did not produce any immediate effects on calcium clearance kinetics in any of those neuronal regions. Although cytosolic calcium clearance was not affected by the inhibition of mitochondria, the magnitude of the calcium clearance delay induced by glycolytic inhibitors in different neuronal compartments was related to their mitochondrial density. Conversely, the endoplasmic reticulum Ca2+-ATPase pump activity is fuelled by both glycolytic and mitochondrial ATP, as evidenced by a minimal change in the endoplasmic reticulum calcium contents in cells treated with either deoxyglucose supplemented with lactate or arsenite. Taken together, these data suggest that calcium clearance in cerebellar granule and purkinje cells relies on the plasma membrane Ca2+-ATPase, and is powered by glycolysis. PMID:20510449

Sugimori, Mutsuyuki; Llinas, Rodolfo R.

2010-01-01

431

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

PubMed Central

?-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

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

432

Comparative neuronal morphology of the cerebellar cortex in afrotherians, carnivores, cetartiodactyls, and primates  

PubMed Central

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

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

433

Cerebellar contributions to visuomotor adaptation and motor sequence learning: an ALE meta-analysis  

PubMed Central

Cerebellar contributions to motor learning are well-documented. For example, under some conditions, patients with cerebellar damage are impaired at visuomotor adaptation and at acquiring new action sequences. Moreover, cerebellar activation has been observed in functional MRI (fMRI) investigations of various motor learning tasks. The early phases of motor learning are cognitively demanding, relying on processes such as working memory, which have been linked to the cerebellum as well. Here, we investigated cerebellar contributions to motor learning using activation likelihood estimation (ALE) meta-analysis. This allowed us to determine, across studies and tasks, whether or not the location of cerebellar activation is constant across differing motor learning tasks, and whether or not cerebellar activation in early learning overlaps with that observed for working memory. We found that different regions of the anterior cerebellum are engaged for implicit and explicit sequence learning and visuomotor adaptation, providing additional evidence for the modularity of cerebellar function. Furthermore, we found that lobule VI of the cerebellum, which has been implicated in working memory, is activated during the early stages of explicit motor sequence learning. This provides evidence for a potential role for the cerebellum in the cognitive processing associated with motor learning. However, though lobule VI was activated across both early explicit sequence learning and working memory studies, there was no spatial overlap between these two regions. Together, our results support the idea of modularity in the formation of internal representations of new motor tasks in the cerebellum, and highlight the cognitive processing relied upon during the early phases of motor skill learning. PMID:23403800

Bernard, Jessica A.; Seidler, Rachael D.

2013-01-01

434

Comparative neuronal morphology of the cerebellar cortex in afrotherians, carnivores, cetartiodactyls, and primates.  

PubMed

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

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

435

Postsynaptic glutamate uptake in rat cerebellar Purkinje cells.  

PubMed Central

1. Whole-cell clamp experiments on Purkinje neurons in rat cerebellar slices were used to test whether glutamate transporters, detected immunocytochemically in the somata and dendrites of the cells, are functional in the cell surface membrane, and to investigate their role in terminating synaptic transmission. 2. A membrane current was detected with the pharmacology, voltage and ion dependence of a glutamate uptake current. Part of the current was generated by an anion conductance activated when uptake occurs. 3. With sodium and glutamate inside the cell, raising the external potassium concentration generated an outward current attributable to reversed operation of glutamate transporters. 4. The magnitude of the uptake current suggested that Purkinje cell transporters could help to terminate transmission at the climbing and parallel fibre to Purkinje cell synapses. Reducing postsynaptic glutamate uptake with intracellular D-aspartate prolonged the climbing fibre EPSC. 5. These data establish the existence of functional postsynaptic glutamate transporters, show that they contribute to terminating synaptic transmission, and suggest that they may play a role in the preferential death of Purkinje cells in ischaemia. PMID:8961192

Takahashi, M; Sarantis, M; Attwell, D

1996-01-01

436

Occipital diploic cranial fasciitis after radiotherapy for a cerebellar medulloblastoma.  

PubMed

Radiation-induced cranial fasciitis is a rare complication of radiotherapy, especially in an intradiploic location. The authors report such a case of cranial fasciitis in a 13-year-old girl previously subjected to cranial radiotherapy for a recurrent cerebellar medulloblastoma. The patient had undergone a gross-total removal of a medulloblastoma followed by no radiation therapy at the age of 10 years. The tumor recurred at the original site 2 years later, warranting a repeat operation with a gross-total tumor removal and subsequent radiation therapy. The follow-up MRI sequence demonstrated no abnormal appearance for 1 year, until a new enhancing mass was found within the occipital bone adjacent to the prior bone window. Following its resection, the new lesion was histologically identified as cranial fasciitis. Differential diagnosis of a well-circumscribed bone lesion should include cranial fasciitis, especially in young children with radiotherapy for a previous intracranial malignancy. Radiotherapy should be considered among the inciting factors in the development of cranial fasciitis. The osteolytic lesions of cranial fasciitis, although nontumoral and self-limited in duration, should be eligible candidates for early, total resection to avoid potential intracranial expansion. PMID:24116980

Wu, Bo; Zhu, Hong; Liu, Weidong; Chen, Longyi

2013-12-01

437

False-Positive Head-Impulse Test in Cerebellar Ataxia  

PubMed Central

The objective of this study was to compare the findings of the bedside head-impulse test (HIT), passive head rotation gain, and caloric irrigation in patients with cerebellar ataxia (CA). In 16 patients with CA and bilaterally pathological bedside HIT, vestibuloocular reflex (VOR) gains were measured during HIT and passive head rotation by scleral search coil technique. Eight of the patients had pathologically reduced caloric responsiveness, while the other eight had normal caloric responses. Those with normal calorics showed a slightly reduced HIT gain (mean?±?SD: 0.73?±?0.15). In those with pathological calorics, gains 80 and 100?ms after the HIT as well as the passive rotation VOR gains were significantly lower. The corrective saccade after head turn occurred earlier in patients with pathological calorics (111?±?62?ms after onset of the HIT) than in those with normal calorics (191?±?17?ms, p?=?0.0064). We identified two groups of patients with CA: those with an isolated moderate HIT deficit only, probably due to floccular dysfunction, and those with combined HIT, passive rotation, and caloric deficit, probably due to a peripheral vestibular deficit. From a clinical point of view, these results show that the bedside HIT alone can be false-positive for establishing a diagnosis of a bilateral peripheral vestibular deficit in patients with CA. PMID:23162531

Kremmyda, Olympia; Kirchner, Hanni; Glasauer, Stefan; Brandt, Thomas; Jahn, Klaus; Strupp, Michael

2012-01-01

438

Genetic effects on the cerebellar role in working memory: same brain, different genes?  

PubMed

Over the past several years, evidence has accumulated showing that the cerebellum plays a significant role in cognitive function. Here we show, in a large genetically informative twin sample (n=430; aged 16-30years), that the cerebellum is strongly, and reliably (n=30 rescans), activated during an n-back working memory task, particularly lobules I-IV, VIIa Crus I and II, IX and the vermis. Monozygotic twin correlations for cerebellar activation were generally much larger than dizygotic twin correlations, consistent with genetic influences. Structural equation models showed that up to 65% of the variance in cerebellar activation during working memory is genetic (averaging 34% across significant voxels), most prominently in the lobules VI, and VIIa Crus I, with the remaining variance explained by unique/unshared environmental factors. Heritability estimates for brain activation in the cerebellum agree with those found for working memory activation in the cerebral cortex, even though cerebellar cyto-architecture differs substantially. Phenotypic correlations between BOLD percent signal change in cerebrum and cerebellum were low, and bivariate modeling indicated that genetic influences on the cerebellum are at least partly specific to the cerebellum. Activation on the voxel-level correlated very weakly with cerebellar gray matter volume, suggesting specific genetic influences on the BOLD signal. Heritable signals identified here should facilitate discovery of genetic polymorphisms influencing cerebellar function through genome-wide association studies, to elucidate the genetic liability to brain disorders affecting the cerebellum. PMID:24128737

Blokland, Gabriëlla A M; McMahon, Katie L; Thompson, Paul M; Hickie, Ian B; Martin, Nicholas G; de Zubicaray, Greig I; Wright, Margaret J

2014-02-01

439

Cerebellar hemorrhage after spinal surgery: case report and review of the literature.  

PubMed

Recent reports indicate that cerebellar hemorrhage after spinal surgery is infrequent, but it is an important and preventable problem. This type of bleeding is thought to occur secondary to venous infarction, but the exact pathogenetic mechanisms are unknown. This report details the case of a 48-year-old woman who developed remote cerebellar hemorrhage after spinal surgery. The patient presented with a herniated lumbar disc, spinal stenosis, and spondylolisthesis, and underwent multiple-level laminectomy, discectomy, and transpedicular fixation. The dura mater was opened accidentally during the operation. There were no neurologic deficits in the early postoperative period; however, 12 h postsurgery the patient complained of headache. This became more severe, and developed progressive dysarthria and vomiting as well. Computed tomography demonstrated small sites of remote cerebellar hemorrhage in both cerebellar hemispheres. The patient was treated medically, and was discharged in good condition. At 6 months after surgery, she was neurologically normal. The case is discussed in relation to the ten previous cases of remote cerebellar hemorrhage documented in the literature. The only possible etiological factors identified in the reported case were opening of the dura and large-volume cerebrospinal fluid loss. PMID:16007466

Konya, Deniz; Ozgen, Serdar; Pamir, M Necmettin

2006-01-01

440

Genetic effects on the cerebellar role in working memory: Same brain, different genes?  

PubMed Central

Over the past several years, evidence has accumulated showing that the cerebellum plays a significant role in cognitive function. Here we show, in a large genetically informative twin sample (n = 430; aged 16–30 years), that the cerebellum is strongly, and reliably (n = 30 rescans), activated during an n-back working memory task, particularly lobules I–IV, VIIa Crus I and II, IX and the vermis. Monozygotic twin correlations for cerebellar activation were generally much larger than dizygotic twin correlations, consistent with genetic influences. Structural equation models showed that up to 65% of the variance in cerebellar activation during working memory is genetic (averaging 34% across significant voxels), most prominently in the lobules VI, and VIIa Crus I, with the remaining variance explained by unique/unshared environmental factors. Heritability estimates for brain activation in the cerebellum agree with those found for working memory activation in the cerebral cortex, even though cerebellar cyto-architecture differs substantially. Phenotypic correlations between BOLD percent signal change in cerebrum and cerebellum were low, and bivariate modeling indicated that genetic influences on the cerebellum are at least partly specific to the cerebellum. Activation on the voxel-level correlated very weakly with cerebellar gray matter volume, suggesting specific genetic influences on the BOLD signal. Heritable signals identified here should facilitate discovery of genetic polymorphisms influencing cerebellar function through genome-wide association studies, to elucidate the genetic liability to brain disorders affecting the cerebellum. PMID:24128737

Blokland, Gabriella A.M.; McMahon, Katie L.; Thompson, Paul M.; Hickie, Ian B.; Martin, Nicholas G.; de Zubicaray, Greig I.; Wright, Margaret J.

2013-01-01

441

The Functional Equivalence of Ascending and Parallel Fiber Inputs in Cerebellar Computation  

PubMed Central

At the center of the computational cerebellar circuitry are Purkinje cells, which integrate synaptic inputs from >150,000 granule cell inputs. Traditional theories of cerebellar function assume that all granule cell inputs are comparable. However, it has recently been suggested that the two anatomically distinct granule cell inputs, ascending and parallel fiber, have different functional roles. By systematically examining the efficacy of patches of granule cells with photostimulation, we found no differences in the efficacy of the two inputs in driving the activity of, or in producing postsynaptic currents in, Purkinje cells in cerebellar slices in vitro. We also found that the activity of Purkinje cells was significantly increased upon stimulation of lateral granule cells in vivo. Moreover, when we estimated parallel fiber and ascending apparent unitary EPSC amplitudes using photostimulation in cerebellar slices in vitro, we found them to be indistinguishable. These results are inconsistent with differential functional roles for these two inputs. Instead, our data support theories of cerebellar computation that consider granule cell inputs to be functionally comparable. PMID:19571137

Walter, Joy T.; Dizon, Maria-Johanna; Khodakhah, Kamran

2014-01-01

442

Large Eddy Simulation of Aircraft Wake Vortices in a Homogeneous Atmospheric Turbulence: Vortex Decay and Descent  

NASA Technical Reports Server (NTRS)

The effects of ambient turbulence on decay and descent of aircraft wake vortices are studied using a validated, three-dimensional: large-eddy simulation model. Numerical simulations are performed in order to isolate the effect of ambient turbulence on the wake vortex decay rate within a neutrally-stratified atmosphere. Simulations are conducted for a range of turbulence intensities, by injecting wake vortex pairs into an approximately homogeneous and isotropic turbulence field. The decay rate of the vortex circulation increases clearly with increasing ambient turbulence level, which is consistent with field observations. Based on the results from the numerical simulations, simple decay models are proposed as functions of dimensionless ambient turbulence intensity (eta) and dimensionless time (T) for the circulation averaged over a range of radial distances. With good agreement with the numerical results, a Gaussian type of vortex decay model is proposed for weak turbulence: while an exponential type of Tortex decay model can be applied for strong turbulence. A relationship for the vortex descent based on above vortex decay model is also proposed. Although the proposed models are based on simulations assuming neutral stratification, the model predictions are compared to Lidar vortex measurements observed during stable, neutral, and unstable atmospheric conditions. In the neutral and unstable atmosphere, the model predictions appear to be in reasonable agreement with the observational data, while in the stably-stratified atmosphere, they largely underestimate the observed circulation decay with consistent overestimation of the observed vortex descent. The underestimation of vortex decay during stably-stratified conditions suggests that stratification has an important influence on vortex decay when ambient levels of turbulence are weak.

Han, Jongil; Lin, Yuh-Lang; Arya, S. Pal; Proctor, Fred H.

1999-01-01