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Results 251 - 300 of 1325
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Ambadar Zara - - 2009
We investigated the correspondence between perceived meanings of smiles and their morphological and dynamic characteristics. Morphological characteristics included co-activation of Orbicularis oculi (AU 6), smile controls, mouth opening, amplitude, and asymmetry of amplitude. Dynamic characteristics included duration, onset and offset velocity, asymmetry of velocity, and head movements. Smile characteristics were ...
Jahnke Claudia - - 2009
OBJECTIVE: To determine the diagnostic accuracy of visual inspection and wet combing in pediculosis capitis (head lice infestation). Visual inspection of 5 predilection sites (temples, behind the ears, and neck) was performed first, followed by wet combing of hair moistened with conditioner. Presence of mobile stages was defined as active ...
Aoki Sachiko - - 2009
Conclusions: The caloric test with head-tilt can be used as a tool for assessing vertical canal function as an office procedure. Objective: Evaluation of vertical canal function. Patients and methods: We provoked caloric response by cold water in the vertiginous patients in supine position. During the culmination of the response ...
Tollin Daniel J - - 2009
Although there have been many anatomical, physiological, and psychophysical studies of auditory development in cat, there have been no comparable studies of the development of the sound pressured transformations by the cat head and pinnae. Because the physical dimensions of the head and pinnae determine the spectral and temporal transformations ...
Ozdek Ali - - 2009
OBJECTIVES: To compare vestibular evoked myogenic potentials (VEMP) between two different methods, head rotation (HR) with unilateral recording and head elevation (HE) with bilateral simultaneous recording. SUBJECTS AND METHODS: Twenty-eight healthy children (56 ears) were involved in the study. The subjects were tested in two different positions: head rotation (HR) ...
Stolbkov Yu K - - 2009
Subjects standing in the dark on a rigid immobile support maintained a vertical posture, which was destabilized by vibrostimulation of both Achilles tendons. Feedback was created via the vestibular pathway using transmastoid galvanic stimulation. Changes in the current in the feedback envelope were made using a linear function based on ...
Minor Lloyd B - - 2009
Processes of vestibular compensation mediate recovery of many aspects of vestibular dysfunction following unilateral vestibular injury. The VOR in response to high-frequency, high-acceleration head movements, however, retains an enduring asymmetry. Head movements that are inhibitory with respect to semicircular canals on the intact side lead to a diminished VOR whereas ...
Lychakov D V - - 2009
Susceptibility to motion sickness was tested by exposing free moving toads to rotation of a stimulator modeled after an amusement park Ferris Wheel. The stimulator provided a gentle stimulation of frequency 0.25 Hz and centrifugal acceleration 0.143 g during 120 min or more without external visual cues. No emetic or ...
Fujimoto Chisato - - 2009
The purpose of this study was to determine the effects of stimulation of the vertical semicircular canals on vestibular evoked myogenic potentials (VEMPs). VEMPs were recorded in 14 subjects seated with their heads and necks tilted 120 degrees forward on the interaural axis. The head was rotated 45 degrees to ...
Bringoux Lionel - - 2009
Numerous studies highlighted the influence of a tilted visual frame on the perception of the visual vertical ('rod-and-frame effect' or RFE). Here, we investigated whether this influence can be modified in a virtual immersive environment (CAVE-like) by the structure of the visual scene and by the adjustment mode allowing visual ...
Sonenblum Sharon Eve - - 2009
PURPOSE: The goal of this study was to monitor and describe the use of power tilt systems in everyday life. Additionally, tilt measurements were used to determine if participants performed regular pressure relieves. METHODS: Wheelchair occupancy and seat position of 16 fulltime power wheelchair users were monitored regularly for 1-2 ...
Olson Kenneth A - - 2009
OBJECTIVES: Limited lower trunk rotation, which includes rotation of the lumbar spine, may hinder or even prevent functional activities. Currently, due to the lack of reliable, valid, and clinically useful tests, there is no standard objective measure of lower trunk rotation that can be easily performed in the clinic. The ...
Higashiyama Atsuki - - 2009
Perception of self-tilt is affected by shearing force acting on the otolith organs in the ears, by pressure acting on the tactile receptors in the skin, and by visual pattern falling on the retinae. We examined how the vestibular, somatosensory, and visual inputs interact in judging self-tilt in roll. Each ...
Knapp Christopher M - - 2009
Previous reports suggest that distance influences horizontal stare OKN gains; however, the effect of distance on vertical OKN and look OKN is unknown. Horizontal and vertical look and stare OKN gains were recorded in 16 healthy volunteers (velocity 38.4 degrees /s) at three distances (0.3 m, 1 m, and 2.5 ...
Brown E T ET Dept. Biomed. Eng., Univ. Rochester, Rochester, NY 14642, USA. - - 2009
Passive translation of the body in space elicits a complex combination of directionally-specific torques that are exerted on the neck. The inertial torques that are produced by linear translation are counteracted by linear vestibular and proprioceptive reflexes that maintain head stability. A novel experimental apparatus was used in this study ...
Byrne Roger A - - 2009
Responses of freshwater organisms to environmental oxygen tensions (PO(2)) have focused on adult (i.e. late developmental) stages, yet responses of embryonic stages to changes in environmental PO(2) must also have implications for organismal biology. Here we assess how the rotational behaviour of the freshwater snail Lymnaea stagnalis changes during development ...
Higashiyama Atsuki - - 2009
We investigated perceived range, perceived velocity, and perceived duration of the body rotating in the frontal plane (in roll). Specifically, to examine how shear to the otoliths in the inner ears and tactile pressure to the trunk affect judgments of range and velocity, in two experiments, we manipulated rotating range ...
Jia HongBo - - 2009
BACKGROUND: Effects of high Gz acceleration can threaten flight safety through loss of consciousness or a lesser-known phenomenon, G-induced vestibular dysfunction (GIVD). There are reports of GIVD following high-G flight or centrifuge exposure. The aim of this study was to explore this problem under controlled conditions using a human centrifuge. ...
Kim Juno - - 2008
Recent studies have shown that the vection in depth experienced by stationary observers viewing constant velocity radial flow can be enhanced by adding simulated viewpoint jitter/oscillation. This study examined the effect of manipulating visual-vestibular conflict on the perceived strength and speed of vection in depth. Four conditions were examined: (i) ...
Zupan Lionel H LH Department of Otology and Laryngology, Harvard Medical School, Boston, MA, - - 2008
The otolith organs respond equivalently to changes in gravitational force due to head tilt and to changes in inertial force due to linear acceleration. It has been shown that the central nervous system (CNS) uses internal models of the laws of physics to distinguish tilt from translation. Models with these ...
Wright W Geoffrey WG Department of Physical Therapy, Temple University, Philadelphia, USA. - - 2009
Dynamic signals from multiple sensory channels must be integrated by the central nervous system to create a unified perception of self-motion and spatial orientation. Using immersive virtual environments, we altered the relative contribution of visual and inertial inputs and evaluated the effects on perceptuomotor outputs. Subjects seated in a tilting ...
Yakusheva Tatyana T Department of Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, - - 2008
Spatial orientation depends critically on the brain's ability to segregate linear acceleration signals arising from otolith afferents into estimates of self-motion and orientation relative to gravity. In the absence of visual information, this ability is known to deteriorate at low frequencies. The cerebellar nodulus/uvula (NU) has been shown to participate ...
Bockisch Christopher J - - 2008
According to Alexander's law (AL), the slow phase velocity of nystagmus of vestibular origin is dependent on horizontal position, with lower velocity when gaze is directed in the slow compared with the fast phase direction. Adaptive changes in the velocity-to-position neural integrator are thought to cause AL. Although these changes ...
Youm Thomas - - 2009
The long head of the biceps has been described as a stabilizing force in the setting of glenohumeral instability. However, data are lacking on the effect of loading the long head of the biceps on glenohumeral kinematics. Six cadaveric shoulders were tested for glenohumeral rotational range of motion and translation ...
Eriksson Lars - - 2008
INTRODUCTION: The somatogravic illusion (SGI) is easily broken when the pilot looks out the aircraft window during daylight flight, but it has proven difficult to break or even reduce the SGI in non-pilots in simulators using synthetic visual scenes. Could visual-flow scenes that accommodate compensatory head movement reduce the SGI ...
Salman Michael S - - 2008
Chiari type II malformation (CII) is a developmental anomaly of the cerebellum and brainstem, which are important structures for processing the vestibulo-ocular reflex (VOR). We investigated the effects of the deformity of CII on the angular VOR during active head motion. Eye and head movements were recorded using an infrared ...
Schubert Michael C MC Department of Otolaryngology Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, MD 21287-0910, USA. - - 2008
Studies on motor learning typically present a constant adaptation stimulus, corresponding to the desired final adaptive state. Studies of the auditory and optokinetic systems provide compelling evidence that neural plasticity is enhanced when the error signal driving adaptation is instead adjusted gradually throughout training. We sought to determine whether the ...
Eckmeier Dennis - - 2008
Optic flow is a main source of information about self movement and the three-dimensional composition of the environment during locomotion. It is processed by the accessory optic system in all vertebrates. The optokinetic response is elicited by rotational optic flow, e.g. in a rotating drum lined with vertical stripes. We ...
Sreenivasa Manish N MN Max Planck Institute for Biological Cybernetics, Spemannstrasse 41, 72076 Tübingen, - - 2008
Walking along a curved path requires coordinated motor actions of the entire body. Here, we investigate the relationship between head and trunk movements during walking. Previous studies have found that the head systematically turns into turns before the trunk does. This has been found to occur at a constant distance ...
Lambert François M FM Laboratoire de Neurobiologie des Réseaux Sensorimoteurs, Centre National de Recherche Scientifique, Unité Mixte de Recherche 7060, Université Paris Descartes, 75270 Paris Cedex 06, - - 2008
Semicircular canals have been sensors of angular acceleration for 450 million years. This vertebrate adaptation enhances survival by implementing postural and visual stabilization during motion in a three-dimensional environment. We used an integrated neuroethological approach in larval Xenopus to demonstrate that semicircular canal dimensions, and not the function of other ...
Chow Dawnis M - - 2008
Sensing and following the chemical plume of food odors is a fundamental challenge faced by many organisms. For flying insects, the task is complicated by wind that distorts the plume and buffets the fly. To maintain an upwind heading, and thus stabilize their orientation in a plume, insects such as ...
McArthur Kimberly L - - 2008
Gaze-stabilizing eye and head responses compensate more effectively for low-frequency rotational motion when such motion stimulates the otolith organs, as during earth-horizontal axis rotations. However, the nature of the otolith signal responsible for this improvement in performance has not been previously determined. In this study, we used combinations of earth-horizontal ...
Hida Kazue - - 2008
CONCLUSIONS: A lengthy alteration of gravity direction produced different effects on the intrinsic horizontal and vertical optokinetic oculomotor systems. OBJECTIVE: To examine both optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN) in a 6 h 6 degrees head-down bedrest study, in which the subjects were kept lying under simulated micro-gravity conditions. ...
Nooij Suzanne A E SA TNO Human Factors, Kampweg 5, 3769 DE, Soesterberg, The Netherlands. - - 2008
Prolonged exposure to hypergravity in a human centrifuge can lead to post-rotary spatial disorientation and motion sickness. These symptoms are mainly provoked by tilting head movements and resemble the Space Adaptation Syndrome. We hypothesized that the occurrence of these post-rotary effects might be related to changes in the velocity storage ...
Simoneau Martin - - 2008
This experiment tests the hypothesis that loading the head would increase head stability. In particular, we hypothesized that an arrangement of the head so that muscle activation is required to counteract a load would significantly increase effective neck stiffness and viscosity, which would be associated with lower peak head angular ...
Xiang Yongqing - - 2008
Little is known about the three-dimensional characteristics of vestibulocollic reflexes during natural locomotion. Here we determined how well head stability is maintained by the angular and linear vestibulocollic reflexes (aVCR, lVCR) during quadrupedal locomotion in rhesus and cynomolgus monkeys. Animals walked on a treadmill at velocities of 0.4-1.25 m/s. Head ...
Marlinski Vladimir V Department of Neurobiology, Pharmacology and Physiology, University of Chicago, 947 E. 58th Street, MC0926, Chicago, IL 60637, USA. - - 2008
The firing behavior of 47 ventro-posterior thalamus neurons was studied in two alert squirrel monkeys during rotations of whole body, head and trunk. A total of 27 of these neurons (57%) were sensitive to spatial motion of the head irrespective of the mode of motion. These neurons responded similarly when ...
Eron Julia N - - 2008
Behavioral experiments indicate that central pathways that process otolith-ocular and perceptual information have adaptive capabilities. Because polarization vectors of otolith afferents are directly related to the electro-mechanical properties of the hair cell bundle, it is unlikely that they change their direction of excitation. This indicates that the adaptation must take ...
Lorincz Erika N - - 2008
We investigated in normal human subjects how semicircular canal and otolith signals interact in the estimation of the subjective visual vertical after constant velocity or constant acceleration roll tilt. In the constant velocity paradigm, subjects were rotated in darkness at +/-60 degrees/s for five complete cycles before being stopped in ...
Tribukait Arne - - 2008
BACKGROUND: In aviation, vestibular-induced spatial disorientation is a significant cause of accidents. Recreating flight-like vestibular stimuli in simulators might be a means for training pilots to respond adequately in disorienting situations. Due to the physical constraints of land-based simulators, the question arises whether a given illusion may be created in ...
Jaffe Jules S - - 2008
Improved knowledge about target tilt can be used to improve acoustic estimates of abundance and to gain insights into the behavioural patterns of exploited marine species. This is because tilt angle strongly affects backscatter, especially at high frequencies. In order to estimate tilt, a dual-transducer system for synchronous observation of ...
Reynolds J S - - 2008
A major goal of this study was to characterize the cervicocollic reflexes (CCRs) in awake squirrel monkeys and compare it to observations in cat. This was carried out by stabilizing the head in space while rotating the lower body. The magnitude and phase of the torque produced between the head ...
Lewis Richard F RF Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts, USA. - - 2008
How does the brain calculate the spatial orientation of the head relative to gravity? Psychophysical measurements are critical to investigate this question, but such measurements have been limited to humans. In non-human primates, behavioral measures have focused on vestibular-mediated eye movements, which do not reflect percepts of head orientation. We ...
Bronstein Adolfo M AM Division of Neuroscience and Mental Health, Imperial College London, UK. - - 2008
Vestibular input to the cerebellum mediates balance and eye movement control. Recent functional MRI studies, however, show midline cerebellar activation during visually induced illusions of self-rotation, thus suggesting that the cerebellum may also contribute to self-motion perception. Here, we investigate self-motion perception directly in patients with vermal (or midline) cerebellar ...
Ohyama Seizo - - 2008
Conclusions. Exposure to a virtual environment for 20 min was sufficient to cause adaptive changes in locomotion in healthy subjects, suggesting that virtual environments might improve locomotor deviation in patients with unilateral labyrinthine defects. Objective. Postural and locomotor control in patients with unilateral labyrinthine defects deviates towards the lesion side. ...
Ceyte Hadrien - - 2008
INTRODUCTION: Neck proprioceptors are essential for orienting the head relative to the trunk. However, it has been shown that the available information about the relationship of gravity to different body parts would augment the clues about their relative orientation. In weightlessness, the absence of relevant body position signals from the ...
Hwang Sungmok - - 2008
A principal components analysis of the median-plane head-related impulse responses (HRIRs) in the CIPIC HRTF database reveals that the individual HRIRs can be reconstructed by a linear combination of 12 principal components (PCs) within 5% of error in the least-squares sense. The PCs include the intersubject and interelevation variations in ...
Seemungal Barry M BM Division of Neurosciences and Mental Health, Imperial College, Charing Cross Hospital Campus, London W6 8RF, United Kingdom. - - 2008
In contrast to vision, the neuro-anatomical substrates of vestibular perception are obscure. The vestibular apparati provide a head angular velocity signal allowing perception of self-motion velocity. Perceived change of angular position-in-space can also be obtained from the vestibular head velocity signal via a process called Path Integration (so-called since displacement ...
Vingerhoets R A A - - 2008
To assess the effects of degrading canal cues for dynamic spatial orientation in human observers, we tested how judgments about visual-line orientation in space (subjective visual vertical task, SVV) and estimates of instantaneous body tilt (subjective body-tilt task, SBT) develop in the course of three cycles of constant-velocity roll rotation. ...
Sarre Guillaume - - 2008
Optic flow is a typical pattern of visual motion that can be used to control locomotion. While the ability to discriminate translational or rotational optic flows have been extensively studied, how these flows control steering during locomotion is not known. The goal of this study was to compare the steering ...
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