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1
Shang, Lei, Wen Bo Wang, Ting Ting Liu, Lei Cai, Hao Wang, and Zhen Dong Dai. "An Equipment Used for Studying the Vestibular Perception of Gekko gecko." Applied Mechanics and Materials 461 (November 2013): 570–76. http://dx.doi.org/10.4028/www.scientific.net/amm.461.570.
Повний текст джерелаАнотація:
The study of vestibule neurons specific firing mode of Gekko gecko under stimulus of different angles and rotating speeds has an important theoretical significance to reveal the control mechanism of Gekko geckos vestibular position as well as to the development of gecko-robots. A vari-angle rotating equipment was made to give different stimulus in study of Gekko geckos vestibular electrophysiology. The equipment mainly consisted of four parts as follows: fastening panel for stereotaxic instrument, shaft locking device, counterweight, driving system. The shaft locking device and counterweight realized tight fixation and torque equilibrium at different angles respectively. Fastening panel matched the general stereotaxic instrument. A stepper motor driver controlled the velocity and acceleration of rotation. Initial experiment verified that the equipment had superiority of easy operation, reliable positioning and accurate control of angle and speed, which indicated that it could meet the demand of the Gekko geckos vestibule research.
2
Joung, Suckhwan. "Performance Analysis of Smoke Control Systems for Elevators based on Pressurization Method." Journal of the Korean Society of Hazard Mitigation 21, no. 3 (June 30, 2021): 105–13. http://dx.doi.org/10.9798/kosham.2021.21.3.105.
Повний текст джерелаАнотація:
The pressurization of emergency or evacuation elevator shafts or duct systems during installation is used for smoke control. In this study, the performance of smoke control systems applied to emergency and evacuation elevators were compared and analyzed using the airflow network analysis program CONTAM 3.2. Under the stack effect condition (temperature difference of 30 ℃), the differential pressure formed in the vestibule was analyzed by adjusting the air volume by changing the value of the loss coefficient factor of the automatic pressure smoke damper. In the case of the duct pressurization method, the air flow in the lower floor was introduced to the elevator shaft owing to the duct pressure and the airflow in the upper floors was from the elevator shaft out to the elevator lobby. In the case of the elevator shaft pressurization method, the pressurized air passing through vestibule from the elevator shaft created a differential pressure at the fire door of vestibule. To maintain the differential pressure in the lower floor, relatively more relief dampers should be installed in the upper floors as compared to those in the duct pressurization method.
3
UCHIBORI, Tomoe, Tetsuya AKIYAMA, Takayuki MATSUSHITA, Koji FUJITA, and Satoru TAKADA. "DESIGN OF CONGREGATED VERTICAL SHAFT EXHAUST SYSTEM WITH VESTIBULE PRESSURIZATION SMOKE CONTROL IN UNDERGROUND." Journal of Environmental Engineering (Transactions of AIJ) 74, no. 645 (2009): 1195–202. http://dx.doi.org/10.3130/aije.74.1195.
Повний текст джерела
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Mirzaie Fouladvand, Zeinab, Ebrahim Pourjam, Natsumi Kanzaki, Robin M. Giblin-Davis, and Majid Pedram. "Description of Basilaphelenchus brevicaudatus n. sp. (Aphelenchoidea: Tylaphelenchinae) from a dead forest tree in northern Iran." Nematology 21, no. 2 (2019): 147–58. http://dx.doi.org/10.1163/15685411-00003203.
Повний текст джерелаАнотація:
Summary Basilaphelenchus brevicaudatus n. sp., the third species of this apparently rare genus, is described and illustrated. It was recovered from wood and bark samples from a dead forest tree in the Golestan province of northern Iran. It is typologically characterised by female body length (448 (365-492) μm), three lines in the lateral fields, raised cephalic region having a sclerotised vestibule and cephalic framework, stylet thin with delicate conus and thicker shaft, both parts lacking a visible lumen, and with three elongate, backwardly directed knobs, small, spherical to spade-shaped metacorpus with small, posteriorly located valve (at 72 (58-74)% of metacorpus length), simple vulva without flap at 72.5 (69-78)% of body length, post-vulval uterine sac 32.4 (29.0-37.0) μm long, functional rectum and anus, female tail conical, short (c′ = 2.6 (1.9-3.3) in female, and 2.5 (2.3-2.8) in male), dorsally convex and ventrally concave with blunt end or having a small mucron, both forms with a hyaline-like tip. Males common, with well-curved 9.2 (9.0-10.5) μm long spicules measured along the mid-line, three pairs of small caudal papillae (lacking the single P1 ventral papilla) and no bursa at tail tip, but with hyaline region, similar to females. Basilaphelenchus brevicaudatus n. sp. is compared with the two currently known species of the genus, the type species, B. persicus, and B. grosmannae. Molecular phylogenetic inferences using partial sequences of small and large subunit ribosomal RNA genes (SSU and LSU) from different isolates of the new species revealed that it belongs to the Tylaphelenchinae clade.
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Appiah-Kubi, Kwadwo Osei, Anne Galgon, Ryan Tierney, Richard Lauer, and W. Geoffrey Wright. "Effects of Vestibular Training on Postural Control of Healthy Adults." CommonHealth 1, no. 1 (April 2, 2020): 31–36. http://dx.doi.org/10.15367/ch.v1i1.299.
Повний текст джерелаАнотація:
Background: Postural stability depends on the integration of multisensory inputs to drive motor outputs. When visual and somatosensory input is available and reliable, this reduces the postural control system’s reliance on the vestibular system. Despite this, vestibular loss can still cause severe postural dysfunction (1,2). Training one or more of the three sensory systems can alter sensory weighting and change postural behavior. Vestibular activation exercises, including horizontal and vertical headshaking, influence vestibular-ocular and -motor responses and have been showed to be effective in vestibular rehabilitation (3–8).
Purpose/Hypothesis: To assess sensory reweighting of postural control processing and vestibular-ocular and -motor responses after concurrent vestibular activation with postural training. It was hypothesized that the effect of this training would significantly alter the pattern of sensory weighting by changing the ratio of visual, somatosensory and vestibular dependence needed to maintain postural stability, and significantly decrease vestibular responses.
Methods: Forty-two young healthy individuals (22 females; 23.0+3.9 years; 1.6+0.1 meters) were randomly assigned into four groups: 1) visual feedback weight shift training (WST) coupled with an active horizontal headshake (HHS), 2) same WST with vertical headshake (VHS), 3) WST with no headshake (NHS) and 4) no training/headshake control (CTL) groups. The headshake groups performed an intensive body WST together with horizontal or vertical rhythmic headshake at 80 to 120 beats/minute. The NHS group performed the WST with no headshake while the controls did not perform any training. Five 15-minute training sessions were performed on consecutive days for one week with the weight shift exercises involving upright limits of stability activities on a flat surface, foam or rocker board (Fig. 1). All groups performed baseline- and post-assessments including sensory organization test (SOT) and force platform ramp perturbations, coupled with electromyographic (EMG) recordings. A video head impulse test was also used to record horizontal vestibulo-ocular reflex (VOR) gain. A between- and within-group repeated measures ANOVA was used to analyze five COP sway variables, the equilibrium and composite scores and sensory ratios of the SOT as well as EMG signals and horizontal VOR gain. Similarly, COP variables, EMG, as well as vestibular reflex data (vertical VOR, vestibulo-collic reflex [VCR] and vestibulo-spinal [VSR] gains) during ramp perturbations were analyzed. Alpha level was set at p<.05.
Results: The training showed a significant somatosensory downweighting (p=.050) in the headshake groups compared to the other groups. Training also showed significant decreased horizontal VOR gain (p=.040), faster automatic postural response (p=.003) (Figs. 2-4) with improved flexibility (p=.010) in the headshake groups. Muscle activation pattern in medial gastrocnemius (p=.033) was significantly decreased in the headshake.
Conclusion: The concurrent vestibular activation and weight shift training modifies vestibular-dependent responses after the training intervention as evidenced in somatosensory downweighting, decreased VOR gain, better postural flexibility and faster automatic postural response. Findings suggest this is predominantly due to vestibular adaptation and habituation of VOR, VCR and VSR which induced sensory reweighting.
Clinical relevance: Findings may be used to guide the development of a vestibular-postural rehabilitation intervention in impaired neurological populations, such as with vestibular disorders or sensory integration problems.
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Crawford, J. Douglas, Douglas B. Tweed, and Tutis Vilis. "Static Ocular Counterroll Is Implemented Through the 3-D Neural Integrator." Journal of Neurophysiology 90, no. 4 (October 2003): 2777–84. http://dx.doi.org/10.1152/jn.00231.2003.
Повний текст джерелаАнотація:
Static head roll about the naso-occipital axis is known to produce an opposite ocular counterroll with a gain of approximately 10%, but the purpose and neural mechanism of this response remain obscure. In theory counterroll could be maintained either by direct tonic vestibular inputs to motoneurons, or by a neurally integrated pulse, as observed in the saccade generator and vestibulo-ocular reflex. When simulated together with ocular drift related to torsional integrator failure, the direct tonic input model predicted that the pattern of drift would shift torsionally as in ordinary counterroll, but the integrated pulse model predicted that the equilibrium position of torsional drift would be unaffected by head roll. This was tested experimentally by measuring ocular counterroll in 2 monkeys after injection of muscimol into the mesencephalic interstitial nucleus of Cajal. Whereas 90° head roll produced a mean ocular counterroll of 8.5° (±0.7° SE) in control experiments, the torsional equilibrium position observed during integrator failure failed to counterroll, showing a torsional shift of only 0.3° (±0.6° SE). This result contradicted the direct tonic input model, but was consistent with models that implement counterroll by a neurally integrated pulse.
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Goldman, Mark S., Chris R. S. Kaneko, Guy Major, Emre Aksay, David W. Tank, and H. S. Seung. "Linear Regression of Eye Velocity on Eye Position and Head Velocity Suggests a Common Oculomotor Neural Integrator." Journal of Neurophysiology 88, no. 2 (August 1, 2002): 659–65. http://dx.doi.org/10.1152/jn.2002.88.2.659.
Повний текст джерелаАнотація:
The oculomotor system produces eye-position signals during fixations and head movements by integrating velocity-coded saccadic and vestibular inputs. A previous analysis of nucleus prepositus hypoglossi (nph) lesions in monkeys found that the integration time constant for maintaining fixations decreased, while that for the vestibulo-ocular reflex (VOR) did not. On this basis, it was concluded that saccadic inputs are integrated by the nph, but that the vestibular inputs are integrated elsewhere. We re-analyze the data from which this conclusion was drawn by performing a linear regression of eye velocity on eye position and head velocity to derive the time constant and velocity bias of an imperfect oculomotor neural integrator. The velocity-position regression procedure reveals that the integration time constants for both VOR and saccades decrease in tandem with consecutive nph lesions, consistent with the hypothesis of a single common integrator. The previous evaluation of the integrator time constant relied upon fitting methods that are prone to error in the presence of velocity bias and saccades. The algorithm used to evaluate imperfect fixations in the dark did not account for the nonzero null position of the eyes associated with velocity bias. The phase-shift analysis used in evaluating the response to sinusoidal vestibular input neglects the effect of saccadic resets of eye position on intersaccadic eye velocity, resulting in gross underestimates of the imperfections in integration during VOR. The linear regression method presented here is valid for both fixation and low head velocity VOR data and is easy to implement.
8
Shenoy, Krishna V., David C. Bradley, and Richard A. Andersen. "Influence of Gaze Rotation on the Visual Response of Primate MSTd Neurons." Journal of Neurophysiology 81, no. 6 (June 1, 1999): 2764–86. http://dx.doi.org/10.1152/jn.1999.81.6.2764.
Повний текст джерелаАнотація:
Influence of gaze rotation on the visual response of primate MSTd neurons. When we move forward, the visual image on our retina expands. Humans rely on the focus, or center, of this expansion to estimate their direction of heading and, as long as the eyes are still, the retinal focus corresponds to the heading. However, smooth rotation of the eyes adds nearly uniform visual motion to the expanding retinal image and causes a displacement of the retinal focus. In spite of this, humans accurately judge their heading during pursuit eye movements and during active, smooth head rotations even though the retinal focus no longer corresponds to the heading. Recent studies in macaque suggest that correction for pursuit may occur in the dorsal aspect of the medial superior temporal area (MSTd) because these neurons are tuned to the retinal position of the focus and they modify their tuning during pursuit to compensate partially for the focus shift. However, the question remains whether these neurons also shift focus tuning to compensate for smooth head rotations that commonly occur during gaze tracking. To investigate this question, we recorded from 80 MSTd neurons while monkeys tracked a visual target either by pursuing with their eyes or by vestibulo-ocular reflex cancellation (VORC; whole-body rotation with eyes fixed in head and head fixed on body). VORC is a passive, smooth head rotation condition that selectively activates the vestibular canals. We found that neurons shift their focus tuning in a similar way whether focus displacement is caused by pursuit or by VORC. Across the population, compensation averaged 88 and 77% during pursuit and VORC, respectively (tuning shift divided by the retinal focus to true heading difference). Moreover the degree of compensation during pursuit and VORC was correlated in individual cells ( P< 0.001). Finally neurons that did not compensate appreciably tended to be gain-modulated during pursuit and VORC and may constitute an intermediate stage in the compensation process. These results indicate that many MSTd cells compensate for general gaze rotation, whether produced by eye-in-head or head-in-world rotation, and further implicate MSTd as a critical stage in the computation of heading. Interestingly vestibular cues present during VORC allow many cells to compensate even though humans do not accurately judge their heading in this condition. This suggests that MSTd may use vestibular information to create a compensated heading representation within at least a subpopulation of cells, which is accessed perceptually only when additional cues related to active head rotations are also present.
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Clément, Gilles, Scott J. Wood, Corinna E. Lathan, Robert J. Peterka, and Millard F. Reschke. "Effects of body orientation and rotation axis on pitch visual-vestibular interaction." Journal of Vestibular Research 9, no. 1 (February 1, 1999): 1–11. http://dx.doi.org/10.3233/ves-1999-9101.
Повний текст джерелаАнотація:
Spatial transformations of the vestibular-optokinetic system must account for changes in head position with respect to gravity in order to produce compensatory oculomotor responses. The purpose of this experiment was to study the influence of gravity on the vestibulo-ocular reflex (VOR) in darkness and on visual-vestibular interaction in the pitch plane in human subjects using two different comparisons: (1) Earth-horizontal axis (EHA) rotation about an upright versus a supine body orientation, and (2) Earth-horizontal versus Earth-vertical (EVA) rotation axes. Visual-vestibular responses (VVR) were evaluated by measuring the slow phase velocity of nystagmus induced during sinusoidal motion of the body in the pitch plane (at 0.2 Hz and 0.8 Hz) combined with a constant-velocity vertical optokinetic stimulation (at ±36°/s). The results showed no significant effect on the gain or phase of the VOR in darkness or on the VVR responses at 0.8 Hz between EHA upright and EHA supine body orientations. However, there was a downward shift in the VOR bias in darkness in the supine orientation. There were systematic changes in VOR and VVR between EHA and EVA for 0.2 Hz, including a reduced modulation gain, increased phase lead, and decreased bias during EVA rotation. The same trend was also observed at 0.8 Hz, but at a lesser extent, presumably due to the effects of eccentric rotation in our EVA condition and/or to the different canal input across frequencies. The change in the bias at 0.2 Hz between rotation in darkness and rotation with an optokinetic stimulus was greater than the optokinetic responses without rotation. During EHA, changes in head position relative to gravity preserve graviceptor input to the VVR regardless of body orientation. However, the modifications in VVR gain and phase when the rotation axis is aligned with gravity indicate that this graviceptive information is important for providing compensatory eye movements during visual-vestibular interaction in the pitch plane.
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Haji-Abolhassani, Iman, Daniel Guitton, and Henrietta L. Galiana. "Modeling eye-head gaze shifts in multiple contexts without motor planning." Journal of Neurophysiology 116, no. 4 (October 1, 2016): 1956–85. http://dx.doi.org/10.1152/jn.00605.2015.
Повний текст джерелаАнотація:
During gaze shifts, the eyes and head collaborate to rapidly capture a target (saccade) and fixate it. Accordingly, models of gaze shift control should embed both saccadic and fixation modes and a mechanism for switching between them. We demonstrate a model in which the eye and head platforms are driven by a shared gaze error signal. To limit the number of free parameters, we implement a model reduction approach in which steady-state cerebellar effects at each of their projection sites are lumped with the parameter of that site. The model topology is consistent with anatomy and neurophysiology, and can replicate eye-head responses observed in multiple experimental contexts: 1) observed gaze characteristics across species and subjects can emerge from this structure with minor parametric changes; 2) gaze can move to a goal while in the fixation mode; 3) ocular compensation for head perturbations during saccades could rely on vestibular-only cells in the vestibular nuclei with postulated projections to burst neurons; 4) two nonlinearities suffice, i.e., the experimentally-determined mapping of tectoreticular cells onto brain stem targets and the increased recruitment of the head for larger target eccentricities; 5) the effects of initial conditions on eye/head trajectories are due to neural circuit dynamics, not planning; and 6) “compensatory” ocular slow phases exist even after semicircular canal plugging, because of interconnections linking eye-head circuits. Our model structure also simulates classical vestibulo-ocular reflex and pursuit nystagmus, and provides novel neural circuit and behavioral predictions, notably that both eye-head coordination and segmental limb coordination are possible without trajectory planning.
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Hullar, Timothy E., Charles C. Della Santina, Timo Hirvonen, David M. Lasker, John P. Carey, and Lloyd B. Minor. "Responses of Irregularly Discharging Chinchilla Semicircular Canal Vestibular-Nerve Afferents During High-Frequency Head Rotations." Journal of Neurophysiology 93, no. 5 (May 2005): 2777–86. http://dx.doi.org/10.1152/jn.01002.2004.
Повний текст джерелаАнотація:
Mammalian vestibular-nerve afferents innervating the semicircular canals have been divided into groups according to their discharge regularity, gain at 2-Hz rotational stimulation, and morphology. Low-gain irregular afferents terminate in calyx endings in the central crista, high-gain irregular afferents synapse more peripherally in dimorphic (bouton and calyx) endings, and regular afferents terminate in the peripheral zone as bouton-only and dimorphic endings. The response dynamics of these three groups have been described only up to 4 Hz in previous studies. Reported here are responses of chinchilla semicircular canal vestibular-nerve afferents to rotational stimuli at frequencies up to 16 Hz. The sensitivity of all afferents increased with increasing frequency with the sensitivity of low-gain irregular afferents increasing the most and matching the high-gain irregular afferents at 16 Hz. All afferents increased their phase lead with respect to stimulus velocity at higher frequencies with the highest leads in low-gain irregular afferents and the lowest in regular afferents. No attenuation of sensitivity or shift in phase consistent with the presence of a high-frequency pole over the range tested was noted. Responses were best fit with a torsion-pendulum model combined with a lead operator (τHF1s + 1)(τHF2s + 1). The discharge regularity of individual afferents was correlated to the value of each afferent's lead operator time constants. These findings suggest that low-gain irregular afferents are well suited for encoding the onset of rapid head movements, a property that would be advantageous for initiation of reflexes with short latency such as the vestibulo-ocular reflex.
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Lewald, Jörg, and Hans-Otto Karnath. "Vestibular Influence on Human Auditory Space Perception." Journal of Neurophysiology 84, no. 2 (August 1, 2000): 1107–11. http://dx.doi.org/10.1152/jn.2000.84.2.1107.
Повний текст джерелаАнотація:
We investigated the effect of vestibular stimulation on the lateralization of dichotic sound by cold-water irrigation of the external auditory canal in human subjects. Subjects adjusted the interaural level difference of the auditory stimulus to the subjective median plane of the head. In those subjects in whom dizziness and nystagmus indicated sufficient vestibular stimulation, these adjustments were significantly shifted toward the cooled ear compared with the control condition (irrigation with water at body temperature); i.e., vestibular stimulation induced a shift of the sound image toward the nonstimulated side. The mean magnitude of the shift was 7.3 dB immediately after vestibular stimulation and decreased to 2.5 dB after 5 min. As shown by an additional control experiment, this effect cannot be attributed to a unilateral hearing loss induced by cooling of the auditory periphery. The results indicate the involvement of vestibular afferent information in the perception of sound location during movements of the head and/or the whole body. We thus hypothesize that vestibular information is used by central-nervous mechanisms generating a world-centered representation of auditory space.
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Tollin, Daniel J., Janet L. Ruhland, and Tom C. T. Yin. "The Vestibulo-Auricular Reflex." Journal of Neurophysiology 101, no. 3 (March 2009): 1258–66. http://dx.doi.org/10.1152/jn.90977.2008.
Повний текст джерелаАнотація:
The mammalian orienting response to sounds consists of a gaze shift that can be a combination of head and eye movements. In animals with mobile pinnae, the ears also move. During head movements, vision is stabilized by compensatory rotations of the eyeball within the head because of the vestibulo-ocular reflex (VOR). While studying the gaze shifts made by cats to sounds, a previously uncharacterized compensatory movement was discovered. The pinnae exhibited short-latency, goal-directed movements that reached their target while the head was still moving. The pinnae maintained a fixed position in space by counter-rotating on the head with an equal but opposite velocity to the head movement. We call these compensatory ear movements the vestibulo-auricular reflex (VAR) because they shared many kinematic characteristics with the VOR. Control experiments ruled out efference copy of head position signals and acoustic tracking (audiokinetic) of the source as the cause of the response. The VAR may serve to stabilize the auditory world during head movements.
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Zelenin, P. V., T. G. Deliagina, S. Grillner, and G. N. Orlovsky. "Postural Control in the Lamprey: A Study With a Neuro-Mechanical Model." Journal of Neurophysiology 84, no. 6 (December 1, 2000): 2880–87. http://dx.doi.org/10.1152/jn.2000.84.6.2880.
Повний текст джерелаАнотація:
The swimming lamprey normally maintains the dorsal-side-up orientation due to activity of the postural control system driven by vestibular organs. Commands for postural corrections are transmitted from the brain stem to the spinal cord mainly by the reticulospinal (RS) pathways. As shown in previous studies, RS neurons are activated by contralateral roll tilt, they exhibit a strong dynamic response, but much weaker static response. Here we test a hypothesis that decoding of these commands in the spinal cord is based on the subtraction of signals in the left and right RS pathways. In this study, we used a neuro-mechanical model. An intact lamprey was mounted on a platform that restrained its postural activity but allowed lateral locomotor undulations to occur. The activity in the left and right RS pathways was recorded by implanted electrodes. These natural biological signals were then used to control an electrical motor rotating the animal around its longitudinal axis toward the stronger signal. It was found that this “hybrid” system automatically stabilized a normal orientation of the lamprey in the gravitational field. The system compensated for large postural disturbances (lateral tilt up to ±180°) due to wide angular zones of the gravitational sensitivity of RS neurons. In the nonswimming lamprey, activity of RS neurons and their vestibular responses were considerably reduced, and the system was not able to stabilize the normal orientation. However, the balance could be restored by imposing small oscillations on the lamprey, which elicited additional activation of the vestibular organs. This finding indicates that head oscillations caused by locomotor movements may contribute to postural stabilization. In addition to postural stabilization, the neuro-mechanical model reproduced a number of postural effects characteristic of the lamprey: 1) unilateral eye illumination elicited a lateral tilt (“dorsal light response”) due to a shift of the equilibrium point in the vestibular-driven postural network; 2) removal of one labyrinth resulted in a loss of postural control due to an induced left-right asymmetry in the vestibulo-reticulospinal reflexes, which 3) could be compensated for by asymmetrical visual input. The main conclusion of the present study is that natural supraspinal commands for postural corrections in the roll plane can be effectively decoded on the basis of subtraction of the effects of signals delivered by the left and right RS pathways. Possible mechanisms for this transformation are discussed.
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Dai, Mingjia, Theodore Raphan, Inessa Kozlovskaya, and Bernard Cohen. "Vestibular adaptation to space in monkeys." Otolaryngology–Head and Neck Surgery 119, no. 1 (July 1998): 65–77. http://dx.doi.org/10.1016/s0194-5998(98)70175-5.
Повний текст джерелаАнотація:
Otolith-induced eye movements of rhesus monkeys were studied before and after the 1989 COSMOS 2044 and the 1992 to 1993 COSMOS 2229 flights. Two animals flew in each mission for approximately 2 weeks. After flight, spatial orientation of the angular vestibulo-ocular reflex was altered. In one animal the time constant of postrotatory nystagmus, which had been shortened by head tilts with regard to gravity before flight, was unaffected by the same head tilts after flight. In another animal, eye velocity, which tended to align with a gravitational axis before flight, moved toward a body axis after flight. This shift of orientation disappeared by 7 days after landing. After flight, the magnitude of compensatory ocular counter-rolling was reduced by about 70% in both dynamic and static tilts. Modulation in vergence in response to naso-occipital linear acceleration during off-vertical axis rotation was reduced by more than 50%. These changes persisted for 11 days after recovery. An up and down asymmetry of vertical nystagmus was diminished for 7 days. Gains of the semicircular canal-induced horizontal and vertical angular vestibuloocular reflexes were unaffected in both flights, but the gain of the roll angular vestibuloocular reflex was decreased. These data indicate that there are short- and long-term changes in otolith-induced eye movements after adaptation to microgravity. These experiments also demonstrate the unique value of the monkey as a model for studying effects of vestibular adaptation in space. Eye movements can be measured in three dimensions in response to controlled vestibular and visual stimulation, and the results are directly applicable to human beings. Studies in monkeys to determine how otolith afferent input and central processing is altered by adaptation to microgravity should be an essential component of future space-related research. (Otolaryngol Head Neck Surg 1998;119:65-77.)
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Anastasopoulos, Dimitri, Nausika Ziavra, and Adolfo M. Bronstein. "Large gaze shift generation while standing: the role of the vestibular system." Journal of Neurophysiology 122, no. 5 (November 1, 2019): 1928–36. http://dx.doi.org/10.1152/jn.00343.2019.
Повний текст джерелаАнотація:
The functional significance of vestibular information for the generation of gaze shifts is controversial and less well established than the vestibular contribution to gaze stability. In this study, we asked seven bilaterally avestibular patients to execute voluntary, whole body pivot turns to visual targets up to 180° while standing. In these conditions, not only are the demands imposed on gaze transfer mechanisms more challenging, but also neck proprioceptive input represents an inadequate source of head-in-space motion information. Patients’ body segment was slower and jerky. In the absence of visual feedback, gaze advanced in small steps, closely resembling normal multiple-step gaze-shift patterns, but as a consequence of the slow head motion, target acquisition was delayed. In ~25% of trials, however, patients moved faster but the velocity of prematurely emerging slow-phase compensatory eye movements remained lower than head-in-space velocity due to vestibuloocular failure. During these trials, therefore, gaze advanced toward the target without interruption but, again, taking longer than when normal controls use single-step gaze transfers. That is, even when patients attempted faster gaze shifts, exposing themselves to gaze instability, they acquired distant targets significantly later than controls. Thus, while patients are upright, loss of vestibular information disrupts not only gaze stability but also gaze transfers. The slow and ataxic head and trunk movements introduce significant foveation delays. These deficits explain patients’ symptoms during upright activities and show, for the first time, the clinical significance of losing the so-called “anticompensatory” (gaze shifting) function of the vestibuloocular reflex. NEW & NOTEWORTHY Previous studies in sitting avestibular patients concluded that gaze transfers are not substantially compromised. Still, clinicians know that patients are impeded (e.g., looking side to side before crossing a road). We show that during large gaze transfers while standing, vestibularly derived head velocity signals are critical for the mechanisms governing reorientation to distant targets and multisegmental coordination. Our findings go beyond the traditional role of the vestibular system in gaze stability, extending it to gaze transfers, as well.
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Serrador, J. M., S. J. Wood, P. A. Picot, F. Stein, M. S. Kassam, R. L. Bondar, A. H. Rupert, and T. T. Schlegel. "Effect of acute exposure to hypergravity (GX vs. GZ) on dynamic cerebral autoregulation." Journal of Applied Physiology 91, no. 5 (November 1, 2001): 1986–94. http://dx.doi.org/10.1152/jappl.2001.91.5.1986.
Повний текст джерелаАнотація:
We examined the effects of 30 min of exposure to either +3GX(front-to-back) or +GZ (head-to-foot) centrifugation on cerebrovascular responses to 80° head-up tilt (HUT) in 14 healthy individuals. Both before and after +3 GX or +3 GZ centrifugation, eye-level blood pressure (BPeye), end tidal Pco 2(Pet CO2 ), mean cerebral flow velocity (CFV) in the middle cerebral artery (transcranial Doppler ultrasound), cerebral vascular resistance (CVR), and dynamic cerebral autoregulatory gain (GAIN) were measured with subjects in the supine position and during subsequent 80° HUT for 30 min. Mean BPeyedecreased with HUT in both the GX ( n = 7) and GZ ( n = 7) groups ( P < 0.001), with the decrease being greater after centrifugation only in the GZ group ( P < 0.05). Pet CO2 also decreased with HUT in both groups ( P < 0.01), but the absolute level of decrease was unaffected by centrifugation. CFV decreased during HUT more significantly after centrifugation than before centrifugation in both groups ( P < 0.02). However, these greater decreases were not associated with greater increases in CVR. In the supine position after centrifugation compared with before centrifugation, GAIN increased in both groups ( P < 0.05, suggesting an autoregulatory deficit), with the change being correlated to a measure of otolith function (the linear vestibulo-ocular reflex) in the GX group ( r = 0.76, P < 0.05) but not in the GZ group ( r = 0.24, P = 0.60). However, GAIN was subsequently restored to precentrifugation levels during postcentrifugation HUT (i.e., as BPeye decreased), suggesting that both types of centrifugation resulted in a leftward shift of the cerebral autoregulation curve. We speculate that this leftward shift may have been due to vestibular activation (especially during +GX) or potentially to an adaptation to reduced cerebral perfusion pressure during +GZ.
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Friedman, Rick A., Karen I. Berliner, Marc Bassim, Joseph Ursick, William H. Slattery, Marc S. Schwartz, and Derald E. Brackmann. "A Paradigm Shift in Salvage Surgery for Radiated Vestibular Schwannoma." Otology & Neurotology 32, no. 8 (October 2011): 1322–28. http://dx.doi.org/10.1097/mao.0b013e31822e5b76.
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Creath, Rob, Tim Kiemel, Fay Horak, and John J. Jeka. "The role of vestibular and somatosensory systems in intersegmental control of upright stance." Journal of Vestibular Research 18, no. 1 (July 1, 2008): 39–49. http://dx.doi.org/10.3233/ves-2008-18104.
Повний текст джерелаАнотація:
Upright stance was perturbed using sinusoidal platform rotations to see how vestibular and somatosensory information are used to control segment and intersegmental dynamics in subjects with bilateral vestibular loss (BVL) and healthy controls (C). Subjects stood with eyes closed on a rotating platform (±1.2° for frequencies ranging from 0.01–0.4 Hz in the presence and absence of light fingertip touch. Trunk movement relative to the platform of BVLs was higher than Cs at higher platform frequencies whereas leg movement relative to the platform was similar for both groups. With the addition of light touch, both groups showed similar trunk and leg segment movement relative to the platform. Trunk-leg coordination was in-phase for frequencies below 1 Hz and anti-phase above 1 Hz. Interestingly, BVLs showed evidence of a "legs-leading-trunk" relationship in the shift from in-phase to anti-phase around 1 Hz. Controls showed no preference for either segment to lead the coordinative shift from in- to anti-phase. The results suggest that the balance instability of BVL subjects stems from high variability of the trunk, rather than the legs. The high trunk variability may emerge from the "legs-leading" intersegmental relationship upon which BVLs rely. Because BVLs derive information about self-orientation primarily from the support surface when their eyes are closed, the legs initiate the shift to anti-phase trunk-leg coordination that is necessary for stable upright stance control. Higher trunk variability suggests that this strategy results in lower overall postural stability. Light touch substitutes for vestibular information, leading to lower trunk variability along with a trunk-leg phase shift similar to controls, without a preference for either segment to lead the shift. The results suggest that vestibulospinal control acts primarily to stabilize the trunk in space and to facilitate intersegmental dynamics.
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Alberts, Bart B. G. T., Luc P. J. Selen, and W. Pieter Medendorp. "Age-related reweighting of visual and vestibular cues for vertical perception." Journal of Neurophysiology 121, no. 4 (April 1, 2019): 1279–88. http://dx.doi.org/10.1152/jn.00481.2018.
Повний текст джерелаАнотація:
As we age, the acuity of our sensory organs declines, which may affect our lifestyle. Sensory deterioration in the vestibular system is typically bilateral and gradual, and could lead to problems with balance and spatial orientation. To compensate for the sensory deterioration, it has been suggested that the brain reweights the sensory information sources according to their relative noise characteristics. For rehabilitation and training programs, it is important to understand the consequences of this reweighting, preferably at the individual subject level. We psychometrically examined the age-dependent reweighting of visual and vestibular cues used in spatial orientation in a group of 32 subjects (age range: 19–76 yr). We asked subjects to indicate the orientation of a line (clockwise or counterclockwise relative to the gravitational vertical) presented within an oriented square visual frame when seated upright or with their head tilted 30° relative to the body. Results show that subjects’ vertical perception is biased by the orientation of the visual frame. Both the magnitude of this bias and response variability become larger with increasing age. Deducing the underlying sensory noise characteristics, using Bayesian inference, suggests an age-dependent reweighting of sensory information, with an increasing weight of the visual contextual information. Further scrutiny of the model suggests that this shift in sensory weights is the result of an increase in the noise of the vestibular signal. Our approach quantifies how noise properties of visual and vestibular systems change over the life span, which helps to understand the aging process at the neurocomputational level. NEW & NOTEWORTHY Perception of visual vertical involves a weighted fusion of visual and vestibular tilt cues. Using a Bayesian approach and experimental psychophysics, we quantify how this fusion process changes with age. We show that, with age, the vestibular information is down-weighted whereas the visual weight is increased. This shift in sensory reweighting is primarily due to an age-related increase of the noise of vestibular signals.
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Das, Vallabh E., Louis F. Dell’Osso, and R. John Leigh. "Enhancement of the Vestibulo-Ocular Reflex by Prior Eye Movements." Journal of Neurophysiology 81, no. 6 (June 1, 1999): 2884–92. http://dx.doi.org/10.1152/jn.1999.81.6.2884.
Повний текст джерелаАнотація:
Enhancement of the vestibulo-ocular reflex by prior eye movements. We investigated the effect of visually mediated eye movements made before velocity-step horizontal head rotations in eleven normal human subjects. When subjects viewed a stationary target before and during head rotation, gaze velocity was initially perturbed by ∼20% of head velocity; gaze velocity subsequently declined to zero within ∼300 ms of the stimulus onset. We used a curve-fitting procedure to estimate the dynamic course of the gain throughout the compensatory response to head rotation. This analysis indicated that the median initial gain of compensatory eye movements (mainly because of the vestibulo-ocular reflex, VOR) was 0.8 and subsequently increased to 1.0 after a median interval of 320 ms. When subjects attempted to fixate the remembered location of the target in darkness, the initial perturbation of gaze was similar to during fixation of a visible target (median initial VOR gain 0.8); however, the period during which the gain increased toward 1.0 was >10 times longer than that during visual fixation. When subjects performed horizontal smooth-pursuit eye movements that ended (i.e., 0 gaze velocity) just before the head rotation, the gaze velocity perturbation at the onset of head rotation was absent or small. The initial gain of the VOR had been significantly increased by the prior pursuit movements for all subjects ( P < 0.05; mean increase of 11%). In four subjects, we determined that horizontal saccades and smooth tracking of a head-fixed target (VOR cancellation with eye stationary in the orbit) also increased the initial VOR gain (by a mean of 13%) during subsequent head rotations. However, after vertical saccades or smooth pursuit, the initial gaze perturbation caused by a horizontal head rotation was similar to that which occurred after fixation of a stationary target. We conclude that the initial gain of the VOR during a sudden horizontal head rotation is increased by prior horizontal, but not vertical, visually mediated gaze shifts. We postulate that this “priming” effect of a prior gaze shift on the gain of the VOR occurs at the level of the velocity inputs to the neural integrator subserving horizontal eye movements, where gaze-shifting commands and vestibular signals converge.
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Maes, Leen, Ingeborg Dhooge, Eddy De Vel, Wendy D'haenens, Annelies Bockstael, Hannah Keppler, Birgit Philips, Freya Swinnen, and Bart M. Vinck. "Normative data and test-retest reliability of the sinusoidal harmonic acceleration test, pseudorandom rotation test and velocity step test." Journal of Vestibular Research 18, no. 4 (December 1, 2008): 197–208. http://dx.doi.org/10.3233/ves-2008-18403.
Повний текст джерелаАнотація:
Rotational testing has been used in clinical practice to explore vestibular function. Frequently used stimulus algorithms include: sinusoidal harmonic acceleration test (SHAT), pseudorandom rotation test (PRRT), and velocity step test (VST). The aim of this study was to construct normative data as well as to evaluate the test-retest reliability of those rotational paradigms. One hundred and fifty subjects without vestibular history participated in the normative study. The SHAT was presented at 5 frequencies (0.01, 0.02, 0.05, 0.1, 0.2 Hz), whereas for the PRRT those frequencies were summed. The VST consisted of a rotation to the right and left and was administered twice. Thirty-two volunteers were retested to assess the test-retest reliability. Separate normative data were needed according to sex, stimulus type, and frequency for the SHAT and PRRT, and according to stimulus and direction for the VST. High reliability by means of the intraclass correlation coefficient (ICC) and the method error (ME) was obtained for the SHAT, PRRT, and VST gain, SHAT phase and asymmetry, and VST time constant parameters. The availability of data on the minimal detectable test-retest differences supports the evaluation of rotational responses on a retest session.
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van Welie, Ingrid, and Sascha du Lac. "Bidirectional control of BK channel open probability by CAMKII and PKC in medial vestibular nucleus neurons." Journal of Neurophysiology 105, no. 4 (April 2011): 1651–59. http://dx.doi.org/10.1152/jn.00058.2011.
Повний текст джерелаАнотація:
Large conductance K+ (BK) channels are a key determinant of neuronal excitability. Medial vestibular nucleus (MVN) neurons regulate eye movements to ensure image stabilization during head movement, and changes in their intrinsic excitability may play a critical role in plasticity of the vestibulo-ocular reflex. Plasticity of intrinsic excitability in MVN neurons is mediated by kinases, and BK channels influence excitability, but whether endogenous BK channels are directly modulated by kinases is unknown. Double somatic patch-clamp recordings from MVN neurons revealed large conductance potassium channel openings during spontaneous action potential firing. These channels displayed Ca2+ and voltage dependence in excised patches, identifying them as BK channels. Recording isolated single channel currents at physiological temperature revealed a novel kinase-mediated bidirectional control in the range of voltages over which BK channels are activated. Application of activated Ca2+/calmodulin-dependent kinase II (CAMKII) increased BK channel open probability by shifting the voltage activation range towards more hyperpolarized potentials. An opposite shift in BK channel open probability was revealed by inhibition of phosphatases and was occluded by blockade of protein kinase C (PKC), suggesting that active PKC associated with BK channel complexes in patches was responsible for this effect. Accordingly, direct activation of endogenous PKC by PMA induced a decrease in BK open probability. BK channel activity affects excitability in MVN neurons and bidirectional control of BK channels by CAMKII, and PKC suggests that cellular signaling cascades engaged during plasticity may dynamically control excitability by regulating BK channel open probability.
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Siegler, I., I. Israël, and A. Berthoz. "Shift of the beating field of vestibular nystagmus: an orientation strategy?" Neuroscience Letters 254, no. 2 (September 1998): 93–96. http://dx.doi.org/10.1016/s0304-3940(98)00671-5.
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Jeffries, David J., James O. Pickles, Michael P. Osborne, Peter H. Rhys-Evans, and Spiro D. Comis. "Crosslinks between stereocilia in hair cells of the human and guinea pig vestibular labyrinth." Journal of Laryngology & Otology 100, no. 12 (December 1986): 1367–74. http://dx.doi.org/10.1017/s002221510010115x.
Повний текст джерелаАнотація:
AbstractThe saccules and ampullae of the semicircular canals from human and guinea pig temporal bones were fixed in glutaraldehyde without osmium. Crosslinks were seen between stereocilia of the vestibular hair cells, similar to those previously demonstrated in the guinea pig, although an additional set of crosslinks was displayed: first, horizontal crosslinks were seen between adjacent stereocilia, occupying most of the length of the hair bundle; secondly, a single upward-pointing link ran from the apex of each shorter stereocilium into the shaft of the adjacent taller ster-eocilium; thirdly, an extensive array of horizontal links were demonstrated between stereocilia close to their insertion into the cuticular plate. We suggest that these basal crosslinks support the long vestibular stereocilia rendering them more rigid, and that the upwind pointing crosslinks are responsible for the initiation of sensory transduction.
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Grabherr, Luzia, Leslie N. Russek, Valeria Bellan, Mohammad Shohag, Danny Camfferman, and G. Lorimer Moseley. "The disappearing hand: vestibular stimulation does not improve hand localisation." PeerJ 7 (July 26, 2019): e7201. http://dx.doi.org/10.7717/peerj.7201.
Повний текст джерелаАнотація:
Background Bodily self-consciousness depends on the coherent integration of sensory information. In addition to visual and somatosensory information processing, vestibular contributions have been proposed and investigated. Vestibular information seems especially important for self-location, but remains difficult to study. Methods This randomised controlled experiment used the MIRAGE multisensory illusion box to induce a conflict between the visually- and proprioceptively-encoded position of one hand. Over time, the perceived location of the hand slowly shifts, due to the fact that proprioceptive input is progressively weighted more heavily than the visual input. We hypothesised that left cold caloric vestibular stimulation (CVS) augments this shift in hand localisation. Results The results from 24 healthy participants do not support our hypothesis: CVS had no effect on the estimations with which the perceived position of the hand shifted from the visually- to the proprioceptively-encoded position. Participants were more likely to report that their hand was ‘no longer there’ after CVS. Taken together, neither the physical nor the subjective data provide evidence for vestibular enhanced self-location.
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Medendorp, W. P., B. J. M. Melis, C. C. A. M. Gielen, and J. A. M. Van Gisbergen. "Off-Centric Rotation Axes in Natural Head Movements: Implications for Vestibular Reafference and Kinematic Redundancy." Journal of Neurophysiology 79, no. 4 (April 1, 1998): 2025–39. http://dx.doi.org/10.1152/jn.1998.79.4.2025.
Повний текст джерелаАнотація:
Medendorp, W. P., B.J.M. Melis, C.C.A.M. Gielen, and J.A.M. Van Gisbergen. Off-centric rotation axes in natural head movements: implications for vestibular reafference and kinematic redundancy. J. Neurophysiol. 79: 2025–2039, 1998. Until now, most studies concerning active head movements in three dimensions have used the classical rotation vector description. Although this description yields both the orientation of the head rotation axis and the amount of rotation, it is incomplete because it cannot specify the location of this rotation axis in space. The latter is of importance for a proper picture of the vestibular consequences of active head movements and has relevance for the problem of how the brain deals with the inherent kinematic redundancy of the multijoint head-neck system. With this in mind, we have extended the rotation vector description by applying the helical axes approach, which yields both the classical rotation vector as well as the location of the rotation axis in space. Subjects ( n = 7), whose head movements were recorded optically, were instructed to shift gaze naturally to targets in 12 different directions at an eccentricity of 40°. The results demonstrate that the axes for these head movements occupy consistently different spatial locations. For purely horizontal movements, the rotation axis is located near a point midway between the two ear canals. For gaze shifts in other directions, the rotation axes are located below the ear canals along two circles, one for movements with an upward component (up circle), the other (typically larger in size) for movements with a downward component (down circle). Purely vertical movement (up and down) axes were located on the lower pole of the up and down circles, respectively. It was found that both circles, the upper poles of which coincided, became larger in size as movement amplitude increased, which means that the axis location shifts to lower and more eccentric locations with respect to the skull for larger flexion and extension movements. Although this pattern could be recognized in most subjects, there were consistent intersubject differences in the absolute size of the circles, their increase with movement amplitude, and in the relative sizes of the up and down circles. Because multiple vertebrae are involved in head movements, there are theoretically many possibilities to execute a certain head movement. The differences in circle patterns among subjects indicate different strategies in resolving this kinematic redundancy problem, a fact that was not apparent from the classical rotation vector part of our description, which yielded a rather uniform picture. A simple model suggests that the downward shift of the location of the rotation axis requires a modulation in vestibulo-ocular reflex gain of ≤10% to maintain fixation of a near target during vertical head movement. The involvement of the otolith system in this process remains to be determined.
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Huwe, J. A., and E. H. Peterson. "Differences in the brain stem terminations of large- and small-diameter vestibular primary afferents." Journal of Neurophysiology 74, no. 3 (September 1, 1995): 1362–66. http://dx.doi.org/10.1152/jn.1995.74.3.1362.
Повний текст джерелаАнотація:
1. We visualized the central axons of 32 vestibular afferents from the posterior canal by extracellular application of horseradish peroxidase, reconstructed them in three dimensions, and quantified their morphology. Here we compare the descending limbs of central axons that differ in parent axon diameter. 2. The brain stem distribution of descending limb terminals (collaterals and associated varicosities) varies systematically with parent axon diameter. Large-diameter afferents concentrate their terminals in rostral regions of the medial/descending nuclei. As axon diameter decreases, there is a significant shift of terminal concentration toward the caudal vestibular complex and adjacent brain stem. 3. Rostral and caudal regions of the medial/descending nuclei have different labyrinthine, cerebellar, intrinsic, commissural, and spinal connections; they are believed to play different roles in head movement control. Our data help clarify the functions of large- and small-diameter afferents by showing that they contribute differentially to rostral and caudal vestibular complex.
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Nikolaev, Andrey V., Sergey A. Popov, Elena A. Satygo, and Mikhail A. Postnikov. "Comparison of the surgically assisted orthodontic rehabilitation techniques of patients with transversal maxillary defficiency." Aspirantskiy Vestnik Povolzhiya 19, no. 5-6 (May 28, 2020): 91–97. http://dx.doi.org/10.17816/2072-2354.2019.19.3.98-103.
Повний текст джерелаАнотація:
The article considers comparison of the outcomes of surgically assisted rapid palatal expansion with the use of tooth-borne and bone-borne expansion appliances in patients with transversal maxillary deficiency. 76 computed tomography scans of 38 patients (24 with bone-borne anchorage, 14 with tooth-borne ones) were studied. Examination of the expansion was performed before the treatment onset and after the activation of the screw of the distraction apparatus. Expansion was evaluated in the areas of canines, premolars and first molars. The maximal amount of the vestibular tooth crown inclination was revealed in premolars with tooth-borne appliances. The use of bone-borne appliances allows to achieve the greatest effect of tooth body shift in a vestibular direction.
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IKEDA, TAKUO, TORU SEKITANI, TOSHISHIGE KIDO, KOICHIRO KANAYA, TETSUYA TAHARA, and HIROTAKA HARA. "Equilibrium of Small Animals in "Drop Shaft" Experimentation. Preliminary Study on the Frog with Vestibular Neurectomy." Nippon Jibiinkoka Gakkai Kaiho 97, no. 4 (1994): 703–8. http://dx.doi.org/10.3950/jibiinkoka.97.703.
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Niehof, Nynke, Florian Perdreau, Mathieu Koppen, and W. Pieter Medendorp. "Contributions of optostatic and optokinetic cues to the perception of vertical." Journal of Neurophysiology 122, no. 2 (August 1, 2019): 480–89. http://dx.doi.org/10.1152/jn.00740.2018.
Повний текст джерелаАнотація:
While it has been well established that optostatic and optokinetic cues contribute to the perception of vertical, it is unclear how the brain processes their combined presence with the nonvisual vestibular cues. Using a psychometric approach, we examined the percept of vertical in human participants ( n = 17) with their body and head upright, presented with a visual frame tilted at one of eight orientations (between ±45°, steps of 11.25°) or no frame, surrounded by an optokinetic roll-stimulus (velocity = ±30°/s or stationary). Both cues demonstrate relatively independent biases on vertical perception, with a sinusoidal modulation by frame orientation of ~4° and a general shift of ~1–2° in the rotation direction of the optic flow. Variability was unaffected by frame orientation but was higher with than without optokinetic rotation. An optimal-observer model in which vestibular, optostatic, and optokinetic cues provide independent sources to vertical perception was unable to explain these data. In contrast, a model in which the optokinetic signal biases the internal representation of gravity, which is then optimally integrated with the optostatic cue, provided a good account, at the individual participant level. We conclude that optostatic and optokinetic cues interact differently with vestibular cues in the neural computations for vertical perception. NEW & NOTEWORTHY Static and dynamic visual cues are known to bias the percept of vertical, but how they interact with vestibular cues remains to be established. Guided by an optimal-observer model, the present results suggest that optokinetic information is combined with vestibular information into a single, vestibular-optokinetic estimate, which is integrated with an optostatically derived estimate of vertical.
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Nam, J. H., J. R. Cotton, and J. W. Grant. "Effect of fluid forcing on vestibular hair bundles." Journal of Vestibular Research 15, no. 5-6 (November 1, 2005): 263–78. http://dx.doi.org/10.3233/ves-2005-155-604.
Повний текст джерелаАнотація:
A dynamic 3-D hair bundle model including inertia and viscous fluid drag effects based on the finite element method is presented. Six structural components are used to construct the hair bundle – kinocilium, stereocilia, upper lateral links, shaft links, tip links, and kinocilial links. Fluid drag is distributed on the surface of cilia columns. Bundle mechanics are analyzed under two distinct loading conditions: (1) drag caused by the shear flow of the surrounding endolymph fluid (fluid-forced), (2) a single force applied to the tip of the kinocilium (point-forced). A striolar and a medial extrastriolar vestibular hair cell from the utricle of a turtle are simulated. The striolar cell bundle shows a clear difference in tip link tension profile between fluid-forced and point-forced cases. When the striolar cell is fluid forced, it shows more evenly distributed tip link tensions and is far more sensitive, responding like an on/off switch. The extrastriolar cell does not show noticeable differences between the forcing types. For both forcing conditions, the extrastriolar cell responds serially – the nearest tip links to the kinocilium get tensed first, then the tension propagates to the farther tip links.
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Blouin, J., J. L. Vercher, G. M. Gauthier, J. Paillard, C. Bard, and Y. Lamarre. "Perception of passive whole-body rotations in the absence of neck and body proprioception." Journal of Neurophysiology 74, no. 5 (November 1, 1995): 2216–19. http://dx.doi.org/10.1152/jn.1995.74.5.2216.
Повний текст джерелаАнотація:
1. This study investigated whether accurate perception of body rotation after passive horizontal whole-body rotations in the dark requires the integration of both vestibular and neck-body proprioceptive signals. 2. In the first experiment, the gain of the vestibuloocular reflex (VOR) of normal subjects ("controls") and of a patient without proprioception of the neck and body muscles was assessed by the use of pulse and sinusoidal stimulation. In the second experiment, the subjects reported verbally the magnitude of the body rotations. Finally, in the third experiment, they shifted gaze to the position fixated before the rotation ("vestibular memory-contingent saccades" paradigm). 3. The VOR gain of the patient was similar to that of controls, although the body rotations of the patient were largely overestimated, regardless of whether the patient reported the perceived magnitude verbally or through a gaze shift toward the position gazed at before the rotation. 4. These results suggest that neck muscle proprioception contributes to the vestibular signal calibration at the perceptual level necessary for determining body orientation accurately after rotations in the dark.
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Node, Michiko, Toru Seo, Atsushi Miyamoto, Akiko Adachi, Misako Hashimoto, and Masafumi Sakagami. "Frequency Dynamics Shift of Vestibular Evoked Myogenic Potentials in Patients with Endolymphatic Hydrops." Otology & Neurotology 26, no. 6 (November 2005): 1208–13. http://dx.doi.org/10.1097/01.mao.0000176172.87141.5d.
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Borden, Jonathan A., Jen-san Tsai, and Anita Mahajan. "Effect of subpixel magnetic resonance imaging shifts on radiosurgical dosimetry for vestibular schwannoma." Journal of Neurosurgery 97 (December 2002): 445–49. http://dx.doi.org/10.3171/jns.2002.97.supplement_5.0445.
Повний текст джерелаАнотація:
Object. The purpose of this study was to evaluate subpixel magnetic resonance (MR) imaging shifts of intracanalicular vestibular schwannomas (VSs) with respect to the internal auditory canal (IAC) as documented on computerized tomography (CT) scanning and to investigate the source of imaging-related localization errors in radiosurgery as well as the effect of such shifts on the dosimetry for small targets. Methods. A shift of the stereotactic coordinates of intracanalicular VSs between those determined on MR imaging and those on CT scanning represents an error in localization. A shift vector places the tumor within the IAC and measures the CT scan/MR image discrepancy. The shift vectors were measured in a series of 15 largely intracanalicular VSs (all < 1.5 cm3 in volume). Using dose volume histogram measurements, the overlap between shifted and unshifted tumors and radiosurgical treatment plans were measured. Using plastic and bone phantoms and thermoluminescent dosimetry measurements, the correspondence between CT and MR imaging targets and treatments delivered using the Leksell gamma knife were measured. Combining these measurements, the correspondence between intended and actual treatments was measured. Conclusions. The delivery of radiation to CT-imaged targets was accurate to the limits of measurement (∼ 0.1 mm). The MR imaging shifts seen in the y axis averaged 0.9 mm and in the z axis 0.8 mm. The corresponding percentage of tumor coverage with respect to apparent target shift decreased from 98 to 77%. This represents a significant potential error when targets are defined solely by MR imaging.
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Kleine, J. F., Y. Guan, E. Kipiani, L. Glonti, M. Hoshi, and U. Büttner. "Trunk Position Influences Vestibular Responses of Fastigial Nucleus Neurons in the Alert Monkey." Journal of Neurophysiology 91, no. 5 (May 2004): 2090–100. http://dx.doi.org/10.1152/jn.00849.2003.
Повний текст джерелаАнотація:
Vestibulospinal reflexes play an important role for body stabilization during locomotion and for postural control. For an appropriate distribution of vestibular signals to spinal motoneurons, the orientation of the body relative to the head needs to be taken into account. For different trunk positions, identical vestibular stimuli must activate different sets of muscles to ensure body stabilization. Because the cerebellar vermis and the underlying fastigial nucleus (FN) might be involved in this task, vestibular neurons in the rostral FN of alert rhesus monkeys were recorded during sinusoidal vestibular stimulation (0.1–1.0 Hz) in the roll and pitch planes at different trunk-re-head positions (center and ±45°). From the sensitivity and phase values measured in these planes, the response properties in the intermediate planes and the stimulus orientation eliciting the optimal response [response vector orientation (RVO)] were calculated. In most neurons, the RVOs rotated systematically with respect to the head, when trunk-re-head position was altered, so that they tended to maintain their orientation with respect to the trunk. Sensitivity and phase at the RVO were not affected. This pattern was the same for neurons in the right and left FN and independent of stimulus frequency. The average sensitivity of this partially compensatory RVO shift in response to trunk-re-head displacements, evaluated by linear regression analyses, was 0.59°/° ( n = 73 neurons). These data show that FN neurons may encode vestibular information in a coordinate system that is closer to a trunk-centered than to a head-centered reference frame. They indicate an important role of this nucleus in motor programs related to posture and gait control.
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Abe, Chikara, Toru Kawada, Masaru Sugimachi, and Hironobu Morita. "Interaction between vestibulo-cardiovascular reflex and arterial baroreflex during postural change in rats." Journal of Applied Physiology 111, no. 6 (December 2011): 1614–21. http://dx.doi.org/10.1152/japplphysiol.00501.2011.
Повний текст джерелаАнотація:
To examine a cooperative role for the baroreflex and the vestibular system in controlling arterial pressure (AP) during voluntary postural change, AP was measured in freely moving conscious rats, with or without sinoaortic baroreceptor denervation (SAD) and/or peripheral vestibular lesion (VL). Voluntary rear-up induced a slight decrease in AP (−5.6 ± 0.8 mmHg), which was significantly augmented by SAD (−14.7 ± 1.0 mmHg) and further augmented by a combination of VL and SAD (−21 ± 1.0 mmHg). Thus we hypothesized that the vestibular system sensitizes the baroreflex during postural change. To test this hypothesis, open-loop baroreflex analysis was conducted on anesthetized sham-treated and VL rats. The isolated carotid sinus pressure was increased stepwise from 60 to 180 mmHg while rats were placed horizontal prone or in a 60° head-up tilt (HUT) position. HUT shifted the carotid sinus pressure-sympathetic nerve activity (SNA) relationship (neural arc) to a higher SNA, shifted the SNA-AP relationship (peripheral arc) to a lower AP, and, consequently, moved the operating point to a higher SNA while maintaining AP (from 113 ± 5 to 114 ± 5 mmHg). The HUT-induced neural arc shift was completely abolished in VL rats, whereas the peripheral arc shifted to a lower AP and the operating point moved to a lower AP (from 116 ± 3 to 84 ± 5 mmHg). These results indicate that the vestibular system elicits sympathoexcitation, shifting the baroreflex neural arc to a higher SNA and maintaining AP during HUT.
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Grassi, Silvarosa, Ermelinda Francescangeli, Gianfrancesco Goracci, and Vito E. Pettorossi. "Role of Platelet-Activating Factor in Long-Term Potentiation of the Rat Medial Vestibular Nuclei." Journal of Neurophysiology 79, no. 6 (June 1, 1998): 3266–71. http://dx.doi.org/10.1152/jn.1998.79.6.3266.
Повний текст джерелаАнотація:
Grassi, Silvarosa, Ermelinda Francescangeli, Gianfrancesco Goracci, and Vito E. Pettorossi. Role of platelet-activating factor in long-term potentiation of the rat medial vestibular nuclei. J. Neurophysiol. 79: 3266–3271, 1998. In rat brain stem slices, we investigated the role of platelet activating factor (PAF) in long-term potentiation (LTP) induced in the ventral part of the medial vestibular nuclei (MVN) by high-frequency stimulation (HFS) of the primary vestibular afferent. The synaptosomal PAF receptor antagonist, BN-52021 was administered before and after HFS. BN-52021 did not modify the vestibular potentials under basal conditions, but it reduced the magnitude of potentiation induced by HFS, which completely developed after the drug wash-out. The same effect was obtained by using CV-62091, a more potent PAF antagonist at microsomal binding sites, but with concentrations higher than those of BN-52021. By contrast both BN-52021 and CV-6209 had no effect on the potentiation once induced. This demonstrates that PAF is involved in the induction but not in the maintenance of vestibular long-term effect through activation of synaptosomal PAF receptors. In addition, we analyzed the effect of the PAFanalogue, 1 - O - hexadecyl - 2 - O - (methylcarbamyl) - sn - glycero - 3phosphocoline (MC-PAF) and the inactive PAF metabolite, 1- O-hexadecyl- sn-glycero-3-phosphocoline (Lyso-PAF) on vestibular responses. Our results show that MC-PAF, but not Lyso-PAF induced potentiation. This potentiation was prevented by d,l-2-amino 5-phosphonopentanoic acid, suggesting an involvement of N-methyl-d-aspartate receptors. Furthermore, under BN-52021 and CV-6209, the MC-PAF potentiation was reduced or abolished. The dose-effect curve of MC-PAF showed a shift to the right greater under BN-52021 than under CV-6209, confirming the main dependence of MC-PAF potentiation on the activation of synaptosomal PAF receptors. Our results suggest that PAF can be released in the MVN after the activation of postsynaptic mechanisms triggering LTP, and it may act as a retrograde messenger which activates the presynaptic mechanisms facilitating synaptic plasticity.
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Scinicariello, Anthony P., J. Timothy Inglis, and J. J. Collins. "The effects of stochastic monopolar galvanic vestibular stimulation on human postural sway." Journal of Vestibular Research 12, no. 2-3 (June 27, 2003): 77–85. http://dx.doi.org/10.3233/ves-2003-122-303.
Повний текст джерелаАнотація:
Galvanic vestibular stimulation (GVS) is a technique in which small currents are delivered transcutaneously to the afferent nerve endings of the vestibular system through electrodes placed over the mastoid bones. The applied current alters the firing rates of the peripheral vestibular afferents, causing a shift in a standing subject's vestibular perception and a corresponding postural sway. Previously, we showed that in subjects who are facing forward, stochastic bipolar binaural GVS leads to coherent stochastic mediolateral postural sway. The goal of this pilot study was to extend that work and to test the hypothesis that in subjects who are facing forward, stochastic monopolar binaural GVS leads to coherent stochastic anteroposterior postural sway. Stochastic monopolar binaural GVS was applied to ten healthy young subjects. Twenty-four trials, each containing a different galvanic input stimulus from among eight different frequency ranges, were conducted on each subject. Postural sway was evaluated through analysis of the center-of-pressure (COP) displacements under each subject's feet. Spectral analysis was performed on the galvanic stimuli and the COP displacement time series to calculate the coherence spectra. Significant coherence was found between the galvanic input signal and the anteroposterior COP displacement in some of the trials (i.e., at least one) in nine of the ten subjects. In general, the coherence values were highest for the mid-range frequencies that were tested, and lowest for the low- and high-range frequencies. However, the coherence values we obtained were lower than those we previously reported for stochastic bipolar binaural GVS and mediolateral sway. These differences may be due to fundamental characteristics of the vestibular system such as lower sensitivity to symmetric changes in afferent firing dynamics, and/or differences between the biomechanics of anteroposterior and mediolateral sway.
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Thompson, Jill, and Ted Begenisich. "External TEA Block of Shaker K+ Channels Is Coupled to the Movement of K+ Ions within the Selectivity Filter." Journal of General Physiology 122, no. 2 (July 28, 2003): 239–46. http://dx.doi.org/10.1085/jgp.200308848.
Повний текст джерелаАнотація:
Recent molecular dynamic simulations and electrostatic calculations suggested that the external TEA binding site in K+ channels is outside the membrane electric field. However, it has been known for some time that external TEA block of Shaker K+ channels is voltage dependent. To reconcile these two results, we reexamined the voltage dependence of block of Shaker K+ channels by external TEA. We found that the voltage dependence of TEA block all but disappeared in solutions in which K+ ions were replaced by Rb+. These and other results with various concentrations of internal K+ and Rb+ ions suggest that the external TEA binding site is not within the membrane electric field and that the voltage dependence of TEA block in K+ solutions arises through a coupling with the movement of K+ ions through part of the membrane electric field. Our results suggest that external TEA block is coupled to two opposing voltage-dependent movements of K+ ions in the pore: (a) an inward shift of the average position of ions in the selectivity filter equivalent to a single ion moving ∼37% into the pore from the external surface; and (b) a movement of internal K+ ions into a vestibule binding site located ∼13% into the membrane electric field measured from the internal surface. The minimal voltage dependence of external TEA block in Rb+ solutions results from a minimal occupancy of the vestibule site by Rb+ ions and because the energy profile of the selectivity filter favors a more inward distribution of Rb+ occupancy.
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Stewart, Courtney E., Ariane C. Kanicki, David S. Bauer, Richard A. Altschuler, and W. Michael King. "Exposure to Intense Noise Causes Vestibular Loss." Military Medicine 185, Supplement_1 (January 2020): 454–61. http://dx.doi.org/10.1093/milmed/usz206.
Повний текст джерелаАнотація:
ABSTRACT Introduction The vestibular system is essential for normal postural control and balance. Because of their proximity to the cochlea, the otolith organs are vulnerable to noise. We previously showed that head jerks that evoke vestibular nerve activity were no longer capable of inducing a response after noise overstimulation. The present study adds a greater range of jerk intensities to determine if the response was abolished or required more intense stimulation (threshold shift). Materials and Methods Vestibular short-latency evoked potential (VsEP) measurements were taken before noise exposure and compared to repeated measurements taken at specific time points for 28 days after noise exposure. Calretinin was used to identify changes in calyx-only afferents in the sacculus. Results Results showed that more intense jerk stimuli could generate a VsEP, although it was severely attenuated relative to prenoise values. When the VsEP was evaluated 4 weeks after noise exposure, partial recovery was observed. Conclusion These data suggest that noise overstimulation, such as can occur in the military, could introduce an increased risk of imbalance that should be evaluated before returning a subject to situations that require normal agility and motion. Moreover, although there is recovery with time, some dysfunction persists for extended periods.
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Paulin, Michael G., Mark E. Nelson, and James M. Bower. "DYNAMICS OF COMPENSATORY EYE MOVEMENT CONTROL: AN OPTIMAL ESTIMATION ANALYSIS OF THE VESTIBULO-OCULAR REFLEX." International Journal of Neural Systems 01, no. 01 (January 1989): 23–29. http://dx.doi.org/10.1142/s0129065789000426.
Повний текст джерелаАнотація:
Head movements in vertebrates give rise to involuntary eye movements that stabilize visual images on the retina. Previous models of the vestibulo-ocular reflex (VOR), one of the neural mechanisms responsible for stabilizing the eyes during head movements, have assumed that the VOR transfer function should have unity gain and 180° phase shift. Experimental measurements of VOR gain and phase, however, exhibit frequency dependencies that are not easily interpreted within the framework of existing models. We reanalyze the problem of VOR control using stochastic optimal estimation theory and show that VOR dynamics, in general, should differ from the "ideal" unity-gain, 180° phase shift transfer function. We illustrate this approach by computing the optimal VOR transfer function for a simple, second-order dynamical model of a head–neck system. Despite its simplicity, this model is able to give some insight into the dynamical properties of the VOR. In particular, it qualitatively reproduces an experimentally observed gain peak in monkey VOR at high frequencies. The model also predicts that the gain and phase characteristics of the optimal VOR transfer function should depend on the spectrum of natural head movements, possibly giving rise to species-dependent and gait-dependent differences in the VOR transfer function. We suggest that the applicability of optimal estimation extends beyond the control of compensatory eye movements and that it is probably a universal component of movement control in the nervous system.
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Koh, Doo-Yeol, Young-Kook Kim, Kyung-Soo Kim, and Soohyun Kim. "Note: High frequency vibration rejection using a linear shaft actuator-based image stabilizing device via vestibulo-ocular reflex adaptation control method." Review of Scientific Instruments 84, no. 8 (August 2013): 086105. http://dx.doi.org/10.1063/1.4812638.
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Stewart, C. E., D. S. Bauer, A. C. Kanicki, R. A. Altschuler, and W. M. King. "Intense noise exposure alters peripheral vestibular structures and physiology." Journal of Neurophysiology 123, no. 2 (February 1, 2020): 658–69. http://dx.doi.org/10.1152/jn.00642.2019.
Повний текст джерелаАнотація:
The otolith organs play a critical role in detecting linear acceleration and gravity to control posture and balance. Some afferents that innervate these structures can be activated by sound and are at risk for noise overstimulation. A previous report demonstrated that noise exposure can abolish vestibular short-latency evoked potential (VsEP) responses and damage calyceal terminals. However, the stimuli that were used to elicit responses were weaker than those established in previous studies and may have been insufficient to elicit VsEP responses in noise-exposed animals. The goal of this study was to determine the effect of an established noise exposure paradigm on VsEP responses using large head-jerk stimuli to determine if noise induces a stimulus threshold shift and/or if large head-jerks are capable of evoking VsEP responses in noise-exposed rats. An additional goal is to relate these measurements to the number of calyceal terminals and hair cells present in noise-exposed vs. non-noise-exposed tissue. Exposure to intense continuous noise significantly reduced VsEP responses to large stimuli and abolished VsEP responses to small stimuli. This finding confirms that while measurable VsEP responses can be elicited from noise-lesioned rat sacculi, larger head-jerk stimuli are required, suggesting a shift in the minimum stimulus necessary to evoke the VsEP. Additionally, a reduction in labeled calyx-only afferent terminals was observed without a concomitant reduction in the overall number of calyces or hair cells. This finding supports a critical role of calretinin-expressing calyceal-only afferents in the generation of a VsEP response. NEW & NOTEWORTHY This study identifies a change in the minimum stimulus necessary to evoke vestibular short-latency evoked potential (VsEP) responses after noise-induced damage to the vestibular periphery and reduced numbers of calretinin-labeled calyx-only afferent terminals in the striolar region of the sacculus. These data suggest that a single intense noise exposure may impact synaptic function in calyx-only terminals in the striolar region of the sacculus. Reduced calretinin immunolabeling may provide insight into the mechanism underlying noise-induced changes in VsEP responses.
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Sulzman, F. M. "Life sciences space missions. Overview." Journal of Applied Physiology 81, no. 1 (July 1, 1996): 3–6. http://dx.doi.org/10.1152/jappl.1996.81.1.3.
Повний текст джерелаАнотація:
It has been known for many years that weightlessness induces changes in numerous physiological systems: the cardiovascular system declines in both aerobic capacity and orthostatic tolerance; there is a reduction in fluid and electrolyte balance, hematocrit, and certain immune parameters; bone and muscle mass and strength are reduced; various neurological responses include space motion sickness and posture and gate alterations. These responses are caused by the hypokinesia of weightlessness, the cephalic fluid shift, the unloading of the vestibular system, stress, and the altered temporal environment.
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Carlson, Matthew L., Elizabeth B. Habermann, Amy E. Wagie, Colin L. Driscoll, Jamie J. Van Gompel, Jeffrey T. Jacob, and Michael J. Link. "The Changing Landscape of Vestibular Schwannoma Management in the United States—A Shift Toward Conservatism." Otolaryngology–Head and Neck Surgery 153, no. 3 (June 30, 2015): 440–46. http://dx.doi.org/10.1177/0194599815590105.
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Dordevic, Milos, Marco Taubert, Patrick Müller, Martin Riemer, Jörn Kaufmann, Anita Hökelmann, and Notger G. Müller. "Which Effects on Neuroanatomy and Path-Integration Survive? Results of a Randomized Controlled Study on Intensive Balance Training." Brain Sciences 10, no. 4 (April 3, 2020): 210. http://dx.doi.org/10.3390/brainsci10040210.
Повний текст джерелаАнотація:
Balancing is a complex task requiring the integration of visual, somatosensory and vestibular inputs. The vestibular system is linked to the hippocampus, a brain structure crucial for spatial orientation. Here we tested the immediate and sustained effects of a one-month-long slackline training program on balancing and orientation abilities as well as on brain volumes in young adults without any prior experience in that skill. On the corrected level, we could not find any interaction effects for brain volumes, but the effect sizes were small to medium. A subsequent within-training-group analysis revealed volumetric increments within the somatosensory cortex and decrements within posterior insula, cerebellum and putamen remained stable over time. No significant interaction effects were observed on the clinical balance and the spatial orientation task two months after the training period (follow-up). We interpret these findings as a shift away from processes crucial for automatized motor output towards processes related to voluntarily controlled movements. The decrease in insular volume in the training group we propose to result from multisensory interaction of the vestibular with the visual and somatosensory systems. The discrepancy between sustained effects in the brain of the training group on the one hand and transient benefits in function on the other may indicate that for the latter to be retained a longer-term practice is required.
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Bao, Tian, Fatemeh Noohi, Catherine Kinnaird, Wendy J. Carender, Vincent J. Barone, Geeta Peethambaran, Susan L. Whitney, Rachael D. Seidler, and Kathleen H. Sienko. "Retention Effects of Long-Term Balance Training with Vibrotactile Sensory Augmentation in Healthy Older Adults." Sensors 22, no. 8 (April 14, 2022): 3014. http://dx.doi.org/10.3390/s22083014.
Повний текст джерелаАнотація:
Vibrotactile sensory augmentation (SA) decreases postural sway during real-time use; however, limited studies have investigated the long-term effects of training with SA. This study assessed the retention effects of long-term balance training with and without vibrotactile SA among community-dwelling healthy older adults, and explored brain-related changes due to training with SA. Sixteen participants were randomly assigned to the experimental group (EG) or control group (CG), and trained in their homes for eight weeks using smart-phone balance trainers. The EG received vibrotactile SA. Balance performance was assessed before, and one week, one month, and six months after training. Functional MRI (fMRI) was recorded before and one week after training for four participants who received vestibular stimulation. Both groups demonstrated significant improvement of SOT composite and MiniBESTest scores, and increased vestibular reliance. Only the EG maintained a minimal detectable change of 8 points in SOT scores six months post-training and greater improvements than the CG in MiniBESTest scores one month post-training. The fMRI results revealed a shift from activation in the vestibular cortex pre-training to increased activity in the brainstem and cerebellum post-training. These findings showed that additional balance improvements were maintained for up to six months post-training with vibrotactile SA for community-dwelling healthy older adults.
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Ramachandran, Ramnarayan, and Stephen G. Lisberger. "Normal Performance and Expression of Learning in the Vestibulo-Ocular Reflex (VOR) at High Frequencies." Journal of Neurophysiology 93, no. 4 (April 2005): 2028–38. http://dx.doi.org/10.1152/jn.00832.2004.
Повний текст джерелаАнотація:
The rotatory vestibulo-ocular reflex (VOR) keeps the visual world stable during head movements by causing eye velocity that is equal in amplitude and opposite in direction to angular head velocity. We have studied the performance of the VOR in darkness for sinusoidal angular head oscillation at frequencies ranging from 0.5 to 50 Hz. At frequencies of ≥25 Hz, the harmonic distortion of the stimulus and response were estimated to be <14 and 22%, respectively. We measured the gain of the VOR (eye velocity divided by head velocity) and the phase shift between eye and head velocity before and after adaptation with altered vision. Before adaptation, VOR gains were close to unity for frequencies ≤20 Hz and increased as a function of frequency reaching values of 3 or 4 at 50 Hz. Eye velocity was almost perfectly out of phase with head velocity for frequencies ≤12.5 Hz, and lagged perfect compensation increasingly as a function of frequency. After adaptive modification of the VOR with magnifying or miniaturizing optics, gain showed maximal changes at frequencies <12.5 Hz, smaller changes at higher frequencies, and no change at frequencies larger than 25 Hz. Between 15 and 25 Hz, the phase of eye velocity led the unmodified VOR by as much as 50° when the gain of the VOR had been decreased, and lagged when the gain of the VOR had been increased. We were able to reproduce the main features of our data with a two-pathway model of the VOR, where the two pathways had different relationships between phase shift and frequency.
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Pomante, A., L. P. J. Selen, and W. P. Medendorp. "Perception of the dynamic visual vertical during sinusoidal linear motion." Journal of Neurophysiology 118, no. 4 (October 1, 2017): 2499–506. http://dx.doi.org/10.1152/jn.00439.2017.
Повний текст джерелаАнотація:
The vestibular system provides information for spatial orientation. However, this information is ambiguous: because the otoliths sense the gravitoinertial force, they cannot distinguish gravitational and inertial components. As a consequence, prolonged linear acceleration of the head can be interpreted as tilt, referred to as the somatogravic effect. Previous modeling work suggests that the brain disambiguates the otolith signal according to the rules of Bayesian inference, combining noisy canal cues with the a priori assumption that prolonged linear accelerations are unlikely. Within this modeling framework the noise of the vestibular signals affects the dynamic characteristics of the tilt percept during linear whole-body motion. To test this prediction, we devised a novel paradigm to psychometrically characterize the dynamic visual vertical—as a proxy for the tilt percept—during passive sinusoidal linear motion along the interaural axis (0.33 Hz motion frequency, 1.75 m/s2peak acceleration, 80 cm displacement). While subjects ( n=10) kept fixation on a central body-fixed light, a line was briefly flashed (5 ms) at different phases of the motion, the orientation of which had to be judged relative to gravity. Consistent with the model’s prediction, subjects showed a phase-dependent modulation of the dynamic visual vertical, with a subject-specific phase shift with respect to the imposed acceleration signal. The magnitude of this modulation was smaller than predicted, suggesting a contribution of nonvestibular signals to the dynamic visual vertical. Despite their dampening effect, our findings may point to a link between the noise components in the vestibular system and the characteristics of dynamic visual vertical.NEW & NOTEWORTHY A fundamental question in neuroscience is how the brain processes vestibular signals to infer the orientation of the body and objects in space. We show that, under sinusoidal linear motion, systematic error patterns appear in the disambiguation of linear acceleration and spatial orientation. We discuss the dynamics of these illusory percepts in terms of a dynamic Bayesian model that combines uncertainty in the vestibular signals with priors based on the natural statistics of head motion.