Rhythmical eye-head-torso rotation alters fore-aft head stabilization during treadmill locomotion in humans*

2000 ◽  
Vol 10 (1) ◽  
pp. 41-49
Author(s):  
Nicole Paquet ◽  
Douglas G.D. Watt ◽  
Luc Lefebvre
Keyword(s):  
Drift Velocity ◽  
Time Course ◽  
Linear Acceleration ◽  
Head Rotation ◽  
Upper Body ◽  
Control Series ◽  
Eyes Closed ◽  
Start Up ◽  
Vestibulo Ocular Reflex ◽  
The Moment

A repetitive manoeuvre called torso rotation (TR) is known to temporarily reduce the gain of the horizontal vestibulo-ocular reflex by 10–15% consists of a series of rhythmical rotations of the eyes, head and upper body executed continuously for 30 minutes while standing. Our aim was to investigate whether TR affects the ability to hold the head in a fixed fore-aft position relative to space while walking on a treadmill with eyes closed. Ten healthy subjects stood in a carefully standardized position on a stationary treadmill. The treadmill started unexpectedly and ran for 4 s at 29 cm/s. The test stimulus was a linear acceleration in the fore-aft direction at the moment of treadmill start-up. Linear head position (i.e., ability to stabilize the head) was measured during and following the stimulus. A mechanical system prevented head rotation. Two series of 60 trials were performed before TR (control 1 and control 2 series) and one after TR. Before TR, subjects drifted rearward at an average drift velocity ± S.D. = 3.1 ± 0.9 cm / s. This drift was reasonably stable over time within and between the two control series. After TR, head holding ability was further impaired, with subjects having more difficulty to stabilize their head after treadmill start-up. In the first 10 trials after the arrest of TR, the average drift velocity was significantly larger than before TR ( 6.1 ± 1.5 cm / sec, p < 0.01). Recovery to control values followed a roughly exponential time course, with 67% impairs the ability to sense and/or respond to fore-aft linear accelerations of the head following treadmill start-up in the absence of vision.

Human Horizontal Vestibulo-Ocular Reflex Initiation: Effects of Acceleration, Target Distance, and Unilateral Deafferentation

1998 ◽  
Vol 80 (3) ◽  
pp. 1151-1166 ◽  
Author(s):  
Benjamin T. Crane ◽  
Joseph L. Demer
Keyword(s):  
Semicircular Canals ◽  
Linear Acceleration ◽  
Head Rotation ◽  
Target Distance ◽  
Whole Body ◽  
Viewing Distance ◽  
Gaze Stabilization ◽  
Ocular Reflex ◽  
Acceleration Period ◽  
Vestibulo Ocular Reflex

Crane, Benjamin T. and Joseph L. Demer. Human horizontal vestibulo-ocular reflex initiation: effects of acceleration, target distance, and unilateral deafferentation. J. Neurophysiol. 80: 1151–1166, 1998. The vestibulo-ocular reflex (VOR) generates compensatory eye movements in response to angular and linear acceleration sensed by semicircular canals and otoliths respectively. Gaze stabilization demands that responses to linear acceleration be adjusted for viewing distance. This study in humans determined the transient dynamics of VOR initiation during angular and linear acceleration, modification of the VOR by viewing distance, and the effect of unilateral deafferentation. Combinations of unpredictable transient angular and linear head rotation were created by whole body yaw rotation about eccentric axes: 10 cm anterior to eyes, centered between eyes, centered between otoliths, and 20 cm posterior to eyes. Subjects viewed a target 500, 30, or 15 cm away that was extinguished immediately before rotation. There were four stimulus intensities up to a maximum peak acceleration of 2,800°/s2. The normal initial VOR response began 7–10 ms after onset of head rotation. Response gain (eye velocity/head velocity) for near as compared with distant targets was increased as early as 1–11 ms after onset of eye movement; this initial effect was independent of linear acceleration. An otolith mediated effect modified VOR gain depending on both linear acceleration and target distance beginning 25–90 ms after onset of head rotation. For rotational axes anterior to the otoliths, VOR gain for the nearest target was initially higher but later became less than that for the far target. There was no gain correction for the physical separation between the eyes and otoliths. With lower acceleration, there was a nonlinear reduction in the early gain increase with close targets although later otolith-mediated effects were not affected. In subjects with unilateral vestibular deafferentation, the initial VOR was quantitatively normal for rotation toward the intact side. When rotating toward the deafferented side, VOR gain remained less than half of normal for at least the initial 55 ms when head acceleration was highest and was not modulated by target distance. After this initial high acceleration period, gain increased to a degree depending on target distance and axis eccentricity. This behavior suggests that the commissural VOR pathways are not modulated by target distance. These results suggest that the VOR is initially driven by short latency ipsilateral target distance dependent and bilateral target-distance independent canal pathways. After 25 ms, otolith inputs contribute to the target distance dependent pathway. The otolith input later grows to eventually dominate the target distance mediated effect. When otolith input is unavailable the target distance mediated canal component persists. Modulation of canal mediated responses by target distance is a nonlinear effect, most evident for high head accelerations.

scholarly journals Effect of Resonant Frequency Vibration on Delayed Onset Muscle Soreness and Resulting Stiffness as Measured by Shear-Wave Elastography

2021 ◽  
Vol 18 (15) ◽  
pp. 7853
Author(s):  
Garrett C. Jones ◽  
Jonathan D. Blotter ◽  
Cameron D. Smallwood ◽  
Dennis L. Eggett ◽  
Darryl J. Cochrane ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Shear Wave ◽  
Time Course ◽  
Biceps Brachii ◽  
Shear Wave Elastography ◽  
Upper Body ◽  
Maximum Voluntary Isometric Contraction ◽  
Post Exercise ◽  
Significant Difference ◽  
Pain Ratings

This study utilized resonant frequency vibration to the upper body to determine changes in pain, stiffness and isometric strength of the biceps brachii after eccentric damage. Thirty-one participants without recent resistance training were randomized into three groups: a Control (C) group and two eccentric exercise groups (No vibration (NV) and Vibration (V)). After muscle damage, participants in the V group received upper body vibration (UBV) therapy for 5 min on days 1–4. All participants completed a visual analog scale (VAS), maximum voluntary isometric contraction (MVIC), and shear wave elastography (SWE) of the bicep at baseline (pre-exercise), 24 h, 48 h, and 1-week post exercise. There was a significant difference between V and NV at 24 h for VAS (p = 0.0051), at 24 h and 1-week for MVIC (p = 0.0017 and p = 0.0016, respectively). There was a significant decrease in SWE for the V group from 24–48 h (p = 0.0003), while there was no significant change in the NV group (p = 0.9341). The use of UBV resonant vibration decreased MVIC decrement and reduced VAS pain ratings at 24 h post eccentric damage. SWE was strongly negatively correlated with MVIC and may function as a predictor of intrinsic muscle state in the time course of recovery of the biceps brachii.

Oculomotor Control of Primary Eye Position Discriminates Between Translation and Tilt

1999 ◽  
Vol 81 (1) ◽  
pp. 394-398 ◽  
Author(s):  
Bernhard J. M. Hess ◽  
Dora E. Angelaki
Keyword(s):  
Dynamic Control ◽  
Linear Acceleration ◽  
Oculomotor System ◽  
Oculomotor Control ◽  
Eye Position ◽  
Axis Orientation ◽  
Fast Phase ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Head Rotations

Hess, Bernhard J. M. and Dora E. Angelaki. Oculomotor control of primary eye position discriminates between translation and tilt. J. Neurophysiol. 81: 394–398, 1999. We have previously shown that fast phase axis orientation and primary eye position in rhesus monkeys are dynamically controlled by otolith signals during head rotations that involve a reorientation of the head relative to gravity. Because of the inherent ambiguity associated with primary otolith afferent coding of linear accelerations during head translation and tilts, a similar organization might also underlie the vestibulo-ocular reflex (VOR) during translation. The ability of the oculomotor system to correctly distinguish translational accelerations from gravity in the dynamic control of primary eye position has been investigated here by comparing the eye movements elicited by sinusoidal lateral and fore-aft oscillations (0.5 Hz ± 40 cm, equivalent to ± 0.4 g) with those during yaw rotations (180°/s) about a vertically tilted axis (23.6°). We found a significant modulation of primary eye position as a function of linear acceleration (gravity) during rotation but not during lateral and fore-aft translation. This modulation was enhanced during the initial phase of rotation when there was concomitant semicircular canal input. These findings suggest that control of primary eye position and fast phase axis orientation in the VOR are based on central vestibular mechanisms that discriminate between gravity and translational head acceleration.

Distribution and metabolism of corticotropin-releasing factor in the rat

1986 ◽  
Vol 64 (6) ◽  
pp. 683-688 ◽  
Author(s):  
Bernard Candas ◽  
Josée Lalonde ◽  
Maurice Normand
Keyword(s):  
Time Course ◽  
Corticotropin Releasing Factor ◽  
Metabolic Clearance ◽  
Sprague Dawley ◽  
Rapid Injection ◽  
Sprague Dawley Rats ◽  
Significant Difference ◽  
The Mean ◽  
The Moment ◽  
The One

To develop a mathematical model of the distribution and metabolism of rat corticotropin-releasing factor (rCRF), the time course of 125I-labelled rCRF in plasma was measured in male Sprague–Dawley rats (i) following a rapid injection of 24 ng rCRF/100 g body weight (BW), or (ii) following a rapid injection of 424 ng rCRF/100 g BW, or (iii) during an infusion at a rate ranging from 0.28 to0.73 ng rCRF∙min−1∙100 g BW−1. The comparison of the one-, two-, and three-compartment models shows that the two-pool structure fits better to the dynamics of CRF in plasma as measured in each rat. Following a rapid injection the decay curve occurs in a biphasic manner; the early phase of disappearance is 25 times faster than the late one. There is no significant difference between the estimates of the metabolic clearance rate following both amplitudes of injection (0.40 ± 0.06 and 0.48 ± 0.05 mL∙min−1∙100 g BW−1). The volume of the first pool, 16.8 ± 1.1 mL/100 g BW, is four times larger than the plasma volume. It would thus appear that CRF is rapidly distributed from plasma into several tissues which are represented in the first pool of the model. The mean residence time of every CRF molecule in the second compartment, from the moment of secretion to its elimination, is from three to four times longer than in the first one. It stays, on average, between 140 min and 3 h in the system before an irreversible exit. At steady state, the disposal rate represents only 3% of the CRF mass of the first compartment every minute. These results could explain the prolonged effects of CRF on pituitary-adrenocortical secretion.

Eye-Head Movement Coordination: Vestibulo-Ocular Reflex Suppression with Head-Fixed Target Fixation1

1991 ◽  
Vol 1 (2) ◽  
pp. 161-170
Author(s):  
Jean-Louis Vercher ◽  
Gabriel M. Gauthier
Keyword(s):  
Eye Movements ◽  
Time Course ◽  
Mental Arithmetic ◽  
Visual Space ◽  
Head Movements ◽  
Total Darkness ◽  
Fixed Target ◽  
Ocular Reflex ◽  
Optokinetic Reflex ◽  
Vestibulo Ocular Reflex

To maintain clear vision, the images on the retina must remain reasonably stable. Head movements are generally dealt with successfully by counter-rotation of the eyes induced by the combined actions of the vestibulo-ocular reflex (VOR) and the optokinetic reflex. A problem of importance relates to the value of the so-called intrinsic gain of the VOR (VORG) in man, and how this gain is modulated to provide appropriate eye movements. We have studied these problems in two situations: 1. fixation of a stationary object of the visual space while the head moves; 2. fixation of an object moving with the head. These two situations were compared to a basic condition in which no visual target was allowed in order to induce “pure” VOR. Eye movements were recorded in seated subjects during stationary sinusoidal and transient rotations around the vertical axis. Subjects were in total darkness (DARK condition) and involved in mental arithmetic. Alternatively, they were provided with a small foveal target, either fixed with respect to earth (earth-fixed target: EFT condition), or moving with them (chair-fixed-target: CFT condition). The stationary rotation experiment was used as baseline for the ensuing experiment and yielded control data in agreement with the literature. In all 3 visual conditions, typical responses to transient rotations were rigorously identical during the first 200 ms. They showed, sequentially, a 16-ms delay of the eye behind the head and a rapid increase in eye velocity during 75 to 80 ms, after which the average VORG was 0.9 ± 0.15. During the following 50 to 100 ms, the gain remained around 0.9 in all three conditions. Beyond 200 ms, the VORG remained around 0.9 in DARK and increased slowly towards 1 or decreased towards zero in the EFT and CFT conditions, respectively. The time-course of the later events suggests that visual tracking mechanisms came into play to reduce retinal slip through smooth pursuit, and position error through saccades. Our data also show that in total darkness VORG is set to 0.9 in man. Lower values reported in the literature essentially reflect predictive properties of the vestibulo-ocular mechanism, particularly evident when the input signal is a sinewave.

Modification of compensatory saccades after aVOR gain recovery

2007 ◽  
Vol 16 (6) ◽  
pp. 285-291
Author(s):  
Michael C. Schubert ◽  
Americo A. Migliaccio ◽  
Charles C. Della Santina
Keyword(s):  
Head Rotation ◽  
Rehabilitation Program ◽  
Inverse Dynamic ◽  
Gaze Stabilization ◽  
Ocular Reflex ◽  
Dynamic Relationship ◽  
Vestibulo Ocular Reflex ◽  
Functional Relevance ◽  
Vestibular Neuronitis ◽  
Eye Velocity

The recruitment of extra-vestibular mechanisms to assist a deficient angular vestibulo-ocular reflex (aVOR) during ipsilesional head rotations is well established and includes saccades of reduced latency that occur in the direction of the lesioned aVOR, termed compensatory saccades (CS). Less well known is the functional relevance of these unique saccades. Here we report a 42 y.o. male diagnosed with right unilateral vestibular hypofunction due to vestibular neuronitis who underwent a vestibular rehabilitation program including gaze stabilization exercises. After three weeks, he had a significant improvement in his ability to see clearly during head rotation. Our data show a reduction in the recruitment and magnitude of CS as well as improved peripheral aVOR gain (eye velocity/head velocity) and retinal eye velocity. Our data suggest an inverse, dynamic relationship between the recruitment of CS and the gain of the aVOR.

Neural Processing of Gravito-Inertial Cues in Humans. II. Influence of the Semicircular Canals During Eccentric Rotation

2001 ◽  
Vol 85 (4) ◽  
pp. 1648-1660 ◽  
Author(s):  
D. M. Merfeld ◽  
L. H. Zupan ◽  
C. A. Gifford
Keyword(s):  
Nervous System ◽  
Time Course ◽  
Rotation Speed ◽  
Linear Acceleration ◽  
Otolith Organs ◽  
Centripetal Acceleration ◽  
Variable Radius ◽  
Fixed Radius ◽  
The Subject ◽  
Roll Tilt

All linear accelerometers, including the otolith organs, respond equivalently to gravity and linear acceleration. To investigate how the nervous system resolves this ambiguity, we measured perceived roll tilt and reflexive eye movements in humans in the dark using two different centrifugation motion paradigms (fixed radius and variable radius) combined with two different subject orientations (facing-motion and back-to-motion). In the fixed radius trials, the radius at which the subject was seated was held constant while the rotation speed was changed to yield changes in the centrifugal force. In variable radius trials, the rotation speed was held constant while the radius was varied to yield a centrifugal force that nearly duplicated that measured during the fixed radius condition. The total gravito-inertial force (GIF) measured by the otolith organs was nearly identical in the two paradigms; the primary difference was the presence (fixed radius) or absence (variable radius) of yaw rotational cues. We found that the yaw rotational cues had a large statistically significant effect on the time course of perceived tilt, demonstrating that yaw rotational cues contribute substantially to the neural processing of roll tilt. We also found that the orientation of the subject relative to the centripetal acceleration had a dramatic influence on the eye movements measured during fixed radius centrifugation. Specifically, the horizontal vestibuloocular reflex (VOR) measured in our human subjects was always greater when the subject faced the direction of motion than when the subjects had their backs toward the motion during fixed radius rotation. This difference was consistent with the presence of a horizontal translational VOR response induced by the centripetal acceleration. Most importantly, by comparing the perceptual tilt responses to the eye movement responses, we found that the translational VOR component decayed as the subjective tilt indication aligned with the tilt of the GIF. This was true for both the fixed radius and variable radius conditions even though the time course of the responses was significantly different for these two conditions. These findings are consistent with the hypothesis that the nervous system resolves the ambiguous measurements of GIF into neural estimates of gravity and linear acceleration. More generally, these findings are consistent with the hypothesis that the nervous system uses internal models to process and interpret sensory motor cues.

State of the Art Solutions in Enterprise Interoperability

2010 ◽  
pp. 201-229 ◽  
Author(s):  
Silke Balzert ◽  
Thomas Burkhart ◽  
Dirk Werth ◽  
Michal Laclavík ◽  
Martin Šeleng ◽  
...  
Keyword(s):  
European Union ◽  
Business Performance ◽  
Electronic Communication ◽  
State Of The Art ◽  
Research Field ◽  
The European Union ◽  
Start Up ◽  
Enterprise Interoperability ◽  
The Moment ◽  
Strategic Motives

More than 99% of European enterprises are SMEs. While collaboration with other enterprises provides potential for improving business performance, enterprise interoperability research has yet to produce results which can be used by SMEs without the need for high start-up costs (e.g. learning, infrastructure and installation costs). Therefore the Commius project (funded by the European Union) aims towards the development of such a “zero costs of entry” interoperability solution for SMEs, allowing them to reuse existing and familiar applications for electronic communication. This chapter provides an overview of the research field “Enterprise Interoperability.” Based on a four layer interoperability framework, this chapter will examine which technical, process-based and semantic solutions for enterprise interoperability are available at the moment and which strategic motives drive or prevail SMEs to engage in E-business activities.

Velocity-length-time relations in canine tracheal smooth muscle

1988 ◽  
Vol 64 (5) ◽  
pp. 2053-2057 ◽  
Author(s):  
C. Y. Seow ◽  
N. L. Stephens
Keyword(s):  
Smooth Muscle ◽  
Goodness Of Fit ◽  
Time Course ◽  
Muscle Length ◽  
Tracheal Smooth Muscle ◽  
Minimum Length ◽  
Shortening Velocity ◽  
Contracting Muscle ◽  
Parabolic Function ◽  
The Moment

Zero-load velocity (V0) as a function of the length of canine tracheal smooth muscle was obtained by applying zero-load clamps to isotonically contracting muscle under various loads. The load clamps were applied at a specific time after onset of contraction. The magnitude of the isotonic load therefore determines the length of the muscle at the moment of release or at the moment the unloaded shortening velocity was measured. A family of such V0-muscle length (L) curves was obtained at 1-s intervals in the time course of contraction. The V0-L curve was fitted by a parabolic function with satisfactory goodness of fit. The maximum shortening velocity at optimum muscle length varied with time, but the minimum length at which V0 diminished to zero was time independent.

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