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https://www.readbyqxmd.com/read/27911755/transformation-of-vestibular-signals-for-the-control-of-standing-in-humans
#1
Patrick A Forbes, Billy L Luu, H F Machiel Van der Loos, Elizabeth A Croft, J Timothy Inglis, Jean-Sébastien Blouin
: During standing balance, vestibular signals encode head movement and are transformed into coordinates that are relevant to maintaining upright posture of the whole body. This transformation must account for head-on-body orientation as well as the muscle actions generating the postural response. Here, we investigate whether this transformation is dependent upon a muscle's ability to stabilize the body along the direction of a vestibular disturbance. Subjects were braced on top of a robotic balance system that simulated the mechanics of standing while being exposed to an electrical vestibular stimulus that evoked a craniocentric vestibular error of head roll...
November 9, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27814310/asymmetries-and-three-dimensional-features-of-vestibular-cross-coupled-stimuli-illuminated-through-modeling
#2
Jan E Holly, M Arjumand Masood, Chiran S Bhandari
Head movements during sustained rotation can cause angular cross-coupling which leads to tumbling illusions. Even though angular vectors predict equal magnitude illusions for head movements in opposite directions, the magnitudes of the illusions are often surprisingly asymmetric, such as during leftward versus rightward yaw while horizontal in a centrifuge. This paper presents a comprehensive investigation of the angular-linear stimulus combinations from eight different published papers in which asymmetries were found...
November 3, 2016: Journal of Vestibular Research: Equilibrium & Orientation
https://www.readbyqxmd.com/read/27741377/comparison-of-set-up-accuracy-among-three-common-immobilisation-systems-for-intensity-modulated-radiotherapy-of-nasopharyngeal-carcinoma-patients
#3
Cheng-Guang Lin, Sen-Kui Xu, Wen-Yan Yao, Yu-Qi Wu, Jian-Lan Fang, Vincent W C Wu
INTRODUCTION: In intensity modulated radiotherapy (IMRT) of nasopharyngeal carcinoma (NPC) patients, an effective immobilisation system is important to minimise set up deviation. This study evaluated the effectiveness of three immobilisation systems by assessing their set up deviations. METHODS: Patients were randomly assigned to one of the three immobilisation systems: (1) supine on head rest and base plate (HB); (2) supine with alpha cradle supporting the head and shoulder (AC); (3) supine with vacuum bag supporting the head and shoulder (VB)...
September 1, 2016: Journal of Medical Radiation Sciences
https://www.readbyqxmd.com/read/27586110/quantitative-evaluation-of-the-occupant-kinematic-response-of-the-thums-50th-percentile-male-model-relative-to-pmhs-laboratory-rollover-tests
#4
David Poulard, Qi Zhang, Jack Ryan Cochran, Bronislaw Gepner, Jason Kerrigan
OBJECTIVE: The objective of the current study was to evaluate the whole-body kinematic response of the Total Human Model for Safety (THUMS) occupant model in controlled laboratory rollover tests by comparing the model response to postmortem human surrogate (PMHS) kinematic response targets published in 2014. METHODS: A computational model of the parametric vehicle buck environment was developed and the AM50 THUMS occupant model (Ver 4.01) was subjected to a pure dynamic roll at 360°/s in trailing-side front-row seating position...
September 2016: Traffic Injury Prevention
https://www.readbyqxmd.com/read/27477714/an-evaluation-of-3d-head-pose-estimation-using-the-microsoft-kinect-v2
#5
John Darby, María B Sánchez, Penelope B Butler, Ian D Loram
The Kinect v2 sensor supports real-time non-invasive 3D head pose estimation. Because the sensor is small, widely available and relatively cheap it has great potential as a tool for groups interested in measuring head posture. In this paper we compare the Kinect's head pose estimates with a marker-based record of ground truth in order to establish its accuracy. During movement of the head and neck alone (with static torso), we find average errors in absolute yaw, pitch and roll angles of 2.0±1.2°, 7.3±3...
July 2016: Gait & Posture
https://www.readbyqxmd.com/read/27339731/head-movement-during-walking-in-the-cat
#6
Humza N Zubair, Irina N Beloozerova, Hai Sun, Vladimir Marlinski
Knowledge of how the head moves during locomotion is essential for understanding how locomotion is controlled by sensory systems of the head. We have analyzed head movements of the cat walking along a straight flat pathway in the darkness and light. We found that cats' head left-right translations, and roll and yaw rotations oscillated once per stride, while fore-aft and vertical translations, and pitch rotations oscillated twice. The head reached its highest vertical positions during second half of each forelimb swing, following maxima of the shoulder/trunk by 20-90°...
September 22, 2016: Neuroscience
https://www.readbyqxmd.com/read/27167275/improved-setup-and-positioning-accuracy-using-a-three-point-customized-cushion-mask-bite-block-immobilization-system-for-stereotactic-reirradiation-of-head-and-neck-cancer
#7
He Wang, Congjun Wang, Samuel Tung, Andrew Wilson Dimmitt, Pei Fong Wong, Mark A Edson, Adam S Garden, David I Rosenthal, Clifton D Fuller, Gary B Gunn, Vinita Takiar, Xin A Wang, Dershan Luo, James N Yang, Jennifer Wong, Jack Phan
The purpose of this study was to investigate the setup and positioning uncertainty of a custom cushion/mask/bite-block (CMB) immobilization system and determine PTV margin for image-guided head and neck stereotactic ablative radiotherapy (HN-SABR). We analyzed 105 treatment sessions among 21 patients treated with HN-SABR for recurrent head and neck cancers using a custom CMB immobilization system. Initial patient setup was performed using the ExacTrac infrared (IR) tracking system and initial setup errors were based on comparison of ExacTrac IR tracking system to corrected online ExacTrac X-rays images registered to treatment plans...
2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/27167267/quantitative-evaluation-of-patient-setup-uncertainty-of-stereotactic-radiotherapy-with-the-frameless-6d-exactrac-system-using-statistical-modeling
#8
Vance Keeling, Sabbir Hossain, Hosang Jin, Ozer Algan, Salahuddin Ahmad, Imad Ali
The purpose of this study is to evaluate patient setup accuracy and quantify indi-vidual and cumulative positioning uncertainties associated with different hardware and software components of the stereotactic radiotherapy (SRS/SRT) with the frameless 6D ExacTrac system. A statistical model is used to evaluate positioning uncertainties of the different components of SRS/SRT treatment with the Brainlab 6D ExacTrac system using the positioning shifts of 35 patients having cranial lesions. All these patients are immobilized with rigid head-and-neck masks, simu-lated with Brainlab localizer and planned with iPlan treatment planning system...
2016: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/27019082/analysis-of-the-setup-uncertainty-and-margin-of-the-daily-exactrac-6d-image-guide-system-for-patients-with-brain-tumors
#9
Se An Oh, Ji Woon Yea, Min Kyu Kang, Jae Won Park, Sung Kyu Kim
This study evaluated the setup uncertainties for brain sites when using BrainLAB's ExacTrac X-ray 6D system for daily pretreatment to determine the optimal planning target volume (PTV) margin. Between August 2012 and April 2015, 28 patients with brain tumors were treated by daily image-guided radiotherapy using the BrainLAB ExacTrac 6D image guidance system of the Novalis-Tx linear accelerator. DUONTM (Orfit Industries, Wijnegem, Belgium) masks were used to fix the head. The radiotherapy was fractionated into 27-33 treatments...
2016: PloS One
https://www.readbyqxmd.com/read/26956976/abnormal-tilt-perception-during-centrifugation-in-patients-with-vestibular-migraine
#10
Joanne Wang, Richard F Lewis
Vestibular migraine (VM), defined as vestibular symptoms caused by migraine mechanisms, is very common but poorly understood. Because dizziness is often provoked in VM patients when the semicircular canals and otolith organs are stimulated concurrently (e.g., tilting the head relative to gravity), we measured tilt perception and eye movements in patients with VM and in migraine and normal control subjects during fixed-radius centrifugation, a paradigm that simultaneously modulates afferent signals from the semicircular canals and otoliths organs...
June 2016: Journal of the Association for Research in Otolaryngology: JARO
https://www.readbyqxmd.com/read/26925031/the-effect-of-age-on-improvements-in-vestibulo-ocular-reflexes-and-balance-control-after-acute-unilateral-peripheral-vestibular-loss
#11
Alja Scheltinga, Flurin Honegger, Dionne P H Timmermans, John H J Allum
BACKGROUND: An acute unilateral peripheral vestibular loss (aUVL) initially causes severe gaze and balance control problems. However, vestibulo-ocular reflexes (VOR) and balance control are nearly normal 3 months later as a result of peripheral recovery and/or central compensation. As pre-existing vestibular sensory loss is assumed to be greater in the healthy elderly, this study investigated whether improvements in VOR and balance function over time after aUVL are different for the elderly than for the young...
2016: Frontiers in Neurology
https://www.readbyqxmd.com/read/26730687/microinstability-of-the-hip-and-the-splits-radiograph
#12
Joshua D Harris, Brayden J Gerrie, David M Lintner, Kevin E Varner, Patrick C McCulloch
A normal hip has a natural tendency toward stability because of both osseous and soft tissue structures. Hip motion is primarily rotational around a center of rotation. When the femoral head and its center of rotation translate, with or without rotation, the inherent stability of the femoroacetabular articulation may be lost. The spectrum of hip instability ranges from subtle microinstability to traumatic dislocation. Microinstability may be the cause or the effect of several other hip pathologies. Soft tissue contributions to stability include the static capsule, dynamic musculotendinous units, and underlying generalized connective tissue (eg, Ehlers-Danlos)...
January 2016: Orthopedics
https://www.readbyqxmd.com/read/26699301/utilization-of-optical-tracking-to-assess-efficacy-of-intracranial-immobilization-techniques-in-proton-therapy
#13
Wen C Hsi, Andries N Schreuder, Omar Zeidan
We present a quantitative methodology to measure head interfraction movements within intracranial masks of commercial immobilization devices used for proton radiotherapy. A three-points tracking (3PtTrack) method was developed to measure the mask location for each treatment field over an average of 10 fractions for seven patients. Five patients were treated in supine with the Qfix Base-of-Skull (BoS) headframe, and two patients were treated in prone with the CIVCO Uni-frame baseplate. Patients were first localized by an in-room, image-guidance (IG) system, and then the mask location was measured using the 3PtTrack method...
2015: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/26614577/effect-of-head-pitch-and-roll-orientations-on-magnetically-induced-vertigo
#14
Omar S Mian, Yan Li, Andre Antunes, Paul M Glover, Brian L Day
KEY POINTS: Lying supine in a strong magnetic field, such as in magnetic resonance imaging scanners, can induce a perception of whole-body rotation. The leading hypothesis to explain this invokes a Lorentz force mechanism acting on vestibular endolymph that acts to stimulate semicircular canals. The hypothesis predicts that the perception of whole-body rotation will depend on head orientation in the field. Results showed that the direction and magnitude of apparent whole-body rotation while stationary in a 7 T magnetic field is influenced by head orientation...
February 15, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/26607469/comparative-analysis-of-pharmacological-treatments-with-n-acetyl-dl-leucine-tanganil-and-its-two-isomers-n-acetyl-l-leucine-and-n-acetyl-d-leucine-on-vestibular-compensation-behavioral-investigation-in-the-cat
#15
Brahim Tighilet, Jacques Leonard, Laurence Bernard-Demanze, Michel Lacour
Head roll tilt, postural imbalance and spontaneous nystagmus are the main static vestibular deficits observed after an acute unilateral vestibular loss (UVL). In the UVL cat model, these deficits are fully compensated over 6 weeks as the result of central vestibular compensation. N-Acetyl-dl-leucine is a drug prescribed in clinical practice for the symptomatic treatment of acute UVL patients. The present study investigated the effects of N-acetyl-dl-leucine on the behavioral recovery after unilateral vestibular neurectomy (UVN) in the cat, and compared the effects of each of its two isomers N-acetyl-L-leucine and N-acetyl-D-leucine...
December 15, 2015: European Journal of Pharmacology
https://www.readbyqxmd.com/read/26454323/predictability-in-orbital-reconstruction-a-human-cadaver-study-part-ii-navigation-assisted-orbital-reconstruction
#16
Leander Dubois, Ruud Schreurs, Jesper Jansen, Thomas J J Maal, Harald Essig, Peter J J Gooris, Alfred G Becking
Preformed orbital reconstruction plates are useful for treating orbital defects. However, intraoperative errors can lead to misplaced implants and poor outcomes. Navigation-assisted surgery may help optimize orbital reconstruction. We aimed to explore whether navigation-assisted surgery is more predictable than traditional orbital reconstruction for optimal implant placement. Pre-injury computed tomography scans were obtained for 10 cadaver heads (20 orbits). Complex orbital fractures (Class III-IV) were created in all orbits, which were reconstructed using a transconjunctival approach with and without navigation...
December 2015: Journal of Cranio-maxillo-facial Surgery
https://www.readbyqxmd.com/read/26436248/the-influence-of-enhanced-side-impact-protection-on-kinematics-and-injury-measures-of-far-or-center-seated-children-in-forward-facing-child-restraints
#17
Hans W Hauschild, John R Humm, Frank A Pintar, Narayan Yoganandan, Bruce Kaufman, Matthew R Maltese, Kristy B Arbogast
OBJECTIVE: To evaluate the influence of forward-facing child restraint systems' (FFCRSs) side impact structure, such as side wings, on the head kinematics and response of a restrained, far- or center-seated 3-year-old anthropomorphic test device (ATD) in oblique sled tests. METHODS: Sled tests were conducted utilizing an FFCRS with large side wings and with the side wings removed. The CRS were attached via LATCH on 2 different vehicle seat fixtures-a small SUV rear bench seat and minivan rear bucket seat-secured to the sled carriage at 20° from lateral...
2015: Traffic Injury Prevention
https://www.readbyqxmd.com/read/26415781/thresholds-for-self-motion-perception-in-roll-without-and-with-visual-fixation-target-the-visualvestibular-interaction-effect
#18
Ognyan I Kolev
The purpose of this study was to establish the selfmotion perception threshold, in roll, in the visualvestibular interaction (VVI) state, creating an oculogyral illusion, and to compare this threshold to the self-motion perception threshold in darkness. A further aim was to investigate the dynamics of the threshold at a low frequency range (0.1-1 Hz) of sinusoidal rotation. Seven healthy subjects were tested. A motion platform was used to generate motion. Single cycles of sinusoidal acceleration at four frequencies (0...
April 2015: Functional Neurology
https://www.readbyqxmd.com/read/26352836/bumblebee-homing-the-fine-structure-of-head-turning-movements
#19
Norbert Boeddeker, Marcel Mertes, Laura Dittmar, Martin Egelhaaf
Changes in flight direction in flying insects are largely due to roll, yaw and pitch rotations of their body. Head orientation is stabilized for most of the time by counter rotation. Here, we use high-speed video to analyse head- and body-movements of the bumblebee Bombus terrestris while approaching and departing from a food source located between three landmarks in an indoor flight-arena. The flight paths consist of almost straight flight segments that are interspersed with rapid turns. These short and fast yaw turns ("saccades") are usually accompanied by even faster head yaw turns that change gaze direction...
2015: PloS One
https://www.readbyqxmd.com/read/26313751/opioid-induced-nausea-involves-a-vestibular-problem-preventable-by-head-rest
#20
Nadine Lehnen, Fabian Heuser, Murat Sağlam, Christian M Schulz, Klaus J Wagner, Masakatsu Taki, Eberhard F Kochs, Klaus Jahn, Thomas Brandt, Stefan Glasauer, Erich Schneider
BACKGROUND AND AIMS: Opioids are indispensable for pain treatment but may cause serious nausea and vomiting. The mechanism leading to these complications is not clear. We investigated whether an opioid effect on the vestibular system resulting in corrupt head motion sensation is causative and, consequently, whether head-rest prevents nausea. METHODS: Thirty-six healthy men (26.6 ± 4.3 years) received an opioid remifentanil infusion (45 min, 0.15 μg/kg/min). Outcome measures were the vestibulo-ocular reflex (VOR) gain determined by video-head-impulse-testing, and nausea...
2015: PloS One
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