Sensation Of Rotation Research Articles

Reabilitação Vestibular: uma Análise de Artigos Científicos Publicados a Partir de 2003

Introduction: Vestibular dysfunction affects individuals of all ages indiscriminately, leading to symptoms such as imbalance, rotational sensation and falls. As a result, it may affect the individual’s daily life, as well as family, social and professional relationships. As rehabilitation (VR) has been used to treat patients with balance disorders, there has been an increasing effort of researchers towards the study of this procedure. Objective: To analyze the scientific articles on VR published between 2003 and 2012. Material and Methods: Articles searches were carried out in the databases Scielo, Medline and Lilacs using the term vestibular rehabilitation. A total of 2443 studies were retrieved, of which 68 met the inclusion criteria. Results: The majority of the articles analyzed had the following profile: published in 2010 (17.65%) by a medical professional (52.94%), with patients not presenting a specific disease (45.59%) and no defined age group (58.82%). Also, most articles did not use the dizziness handicap questionnaire (51.47%). The most used VR protocol was Cawthorne and Cooksey’s (69.56%). Among the studies performed in Brazil there was predominance of the Southeast region (63.89%) and among those produced abroad, the majority were from the United States (46.88%). Conclusions: VR has been consistently presented as an effective procedure for the improvement of activities of daily living and reducing the risk of falling. This procedure is considered a simple and appropriate treatment for dizziness, an extremely common symptom in the population. DESCRIPTORS Dizziness. Vestibular Diseases. Scientific Research and Technological Development.

Illusory self-motion perception evoked by caloric vestibular stimulation in sitting versus supine body positions

The purpose of this study was to determine (i) if a change in the body position that alters the somatosensory afferentation and thus the signal integrated by sensory interaction influences the illusory self-motion perception evoked by cold calorics. If yes, (ii) is the direction of the provoked nystagmus also changed?The vestibular system in 47 healthy subjects was stimulated calorically with 20°C water while in supine and sitting positions but with the head fixed. After each procedure the subjects were asked to describe their self-motion experience, and the provoked nystagmus was analyzed.In 45.7% of these subjects a sensation of yaw rotation was reported while in the sitting position, whereas only 9.6% had this sensation while in the supine position. However, when in the supine position the experience of roll rotation dominated, i.e., 52.1% compared to 5.3% while in the sitting position. Pitch rotation was felt only in the sitting position by 4.3%. There was no such sensation in the supine position. The perception of a full-cycle rotation dominates in the sitting position. In the sitting position 20% of the subjects reported eccentrical head rotation along the circumference of a cone—the top of the cone was located in the neck region. Linear self-motion sensations did not differ in the two positions. The evoked nystagmus in both positions was only horizontal.In conclusion, a change in body position with respect to the gravity vector, while head position is fixed, causes a change in the somatosensory afferentation and modifies the integrated sensory signal by sensory interaction. In turn it influences the self-motion perception evoked by calorics. A change in body position does not affect the direction of nystagmus.

Prism adaptation and neck muscle vibration in healthy individuals: Are two methods better than one?

Studies involving therapeutic combinations reveal an important benefit in the rehabilitation of neglect patients when compared to single therapies. In light of these observations our present work examines, in healthy individuals, sensorimotor and cognitive after-effects of prism adaptation and neck muscle vibration applied individually or simultaneously. We explored sensorimotor after-effects on visuo-manual open-loop pointing, visual and proprioceptive straight-ahead estimations. We assessed cognitive after-effects on the line bisection task. Fifty-four healthy participants were divided into six groups designated according to the exposure procedure used with each: ‘Prism’ (P) group; ‘Vibration with a sensation of body rotation’ (Vb) group; ‘Vibration with a move illusion of the LED’ (Vl) group; ‘Association with a sensation of body rotation’ (Ab) group; ‘Association with a move illusion of the LED’ (Al) group; and ‘Control’ (C) group. The main findings showed that prism adaptation applied alone or combined with vibration showed significant adaptation in visuo-manual open-loop pointing, visual straight-ahead and proprioceptive straight-ahead. Vibration alone produced significant after-effects on proprioceptive straight-ahead estimation in the Vl group. Furthermore all groups (except C group) showed a rightward neglect-like bias in line bisection following the training procedure. This is the first demonstration of cognitive after-effects following neck muscle vibration in healthy individuals. The simultaneous application of both methods did not produce significant greater after-effects than prism adaptation alone in both sensorimotor and cognitive tasks. These results are discussed in terms of transfer of sensorimotor plasticity to spatial cognition in healthy individuals.

Influence of stimulus interval on the habituation of vestibulo-ocular reflex and sensation of rotation in humans

Previous studies in cats revealed that vestibular habituation of the vestibulo-ocular reflex (VOR) only occurs when velocity steps are delivered during the secondary phase nystagmus, suggesting that the presence of anti-compensatory slow phases may trigger the habituation process. We verified this property in humans by comparing vestibular habituation of VOR and sensation of rotation when steps were delivered either immediately after the perception of self-rotation had stopped, which is shortly before the nystagmus reverses direction; or when steps were delivered 60s later, i.e. during the secondary phase. Vestibular habituation of the VOR occurred in both instances. However, the decrease in VOR peak slow phase velocity and time constant was larger when steps were delivered after nystagmus reversal compared to before nystagmus reversal. The duration of the perception of self-rotation habituated equally for both conditions. These results confirm that VOR habituation fully develops only when velocity steps are delivered after the primary phase nystagmus. This finding may be helpful for minimizing the impact of repetitive vestibular stimuli in protocols using crossover design for drug studies, testing recovery in vestibular patients, or training people for different gravitoinertial environments.

Multichannel Vestibular Prosthesis Employing Modulation of Pulse Rate and Current with Alignment Precompensation Elicits Improved VOR Performance in Monkeys

An implantable prosthesis that stimulates vestibular nerve branches to restore the sensation of head rotation and the three-dimensional (3D) vestibular ocular reflex (VOR) could benefit individuals disabled by bilateral loss of vestibular sensation. Our group has developed a vestibular prosthesis that partly restores normal function in animals by delivering biphasic current pulses via electrodes implanted in semicircular canals. Despite otherwise promising results, this approach has been limited by insufficient velocity of VOR response to head movements that should inhibit the implanted labyrinth and by misalignment between direction of head motion and prosthetically elicited VOR. We report that significantly larger VOR eye velocities in the inhibitory direction can be elicited by adapting a monkey to elevated baseline stimulation rate and current prior to stimulus modulation and then concurrently modulating ("co-modulating") both rate and current below baseline levels to encode inhibitory angular head velocity. Co-modulation of pulse rate and current amplitude above baseline can also elicit larger VOR eye responses in the excitatory direction than do either pulse rate modulation or current modulation alone. Combining these stimulation strategies with a precompensatory 3D coordinate transformation improves alignment and magnitude of evoked VOR eye responses. By demonstrating that a combination of co-modulation and precompensatory transformation strategies achieves a robust VOR response in all directions with significantly improved alignment in an animal model that closely resembles humans with vestibular loss, these findings provide a solid preclinical foundation for application of vestibular stimulation in humans.

Co-modulation of stimulus rate and current from elevated baselines expands head motion encoding range of the vestibular prosthesis

An implantable prosthesis that stimulates vestibular nerve branches to restore sensation of head rotation and vision-stabilizing reflexes could benefit individuals disabled by bilateral loss of vestibular sensation. The normal vestibular system encodes head movement by increasing or decreasing firing rate of the vestibular afferents about a baseline firing rate in proportion to head rotation velocity. Our multichannel vestibular prosthesis emulates this encoding scheme by modulating pulse rate and pulse current amplitude above and below a baseline stimulation rate (BSR) and a baseline stimulation current. Unilateral baseline prosthetic stimulation that mimics normal vestibular afferent baseline firing results in vestibulo-ocular reflex (VOR) eye responses with a wider range of eye velocity in response to stimuli modulated above baseline (excitatory) than below baseline (inhibitory). Stimulus modulation about higher than normal baselines resulted in increased range of inhibitory eye velocity, but decreased range of excitatory eye velocity. Simultaneous modulation of rate and current (co-modulation) above all tested baselines elicited a significantly wider range of excitatory eye velocity than rate or current modulation alone. Time constants associated with the recovery of VOR excitability following adaptation to elevated BSRs implicate synaptic vesicle depletion as a possible mechanism for the small range of excitatory eye velocity elicited by rate modulation alone. These findings can be used toward selecting optimal baseline levels for vestibular stimulation that would result in large inhibitory eye responses while maintaining a wide range of excitatory eye velocity via co-modulation.

Galvanic Vestibular Stimulation Produces Sensations of Rotation Consistent with Activation of Semicircular Canal Afferents

Galvanic Vestibular Stimulation Produces Sensations of Rotation Consistent with Activation of Semicircular Canal Afferents

What Does Galvanic Vestibular Stimulation Actually Activate?

What Does Galvanic Vestibular Stimulation Actually Activate?

Anatomofunctional organization of the insular cortex: A study using intracerebral electrical stimulation in epileptic patients

Different lines of evidence suggest that the insular cortex has many important functional roles. Direct electrical stimulation (ES) of the human insular cortex during surgical procedures for epilepsy, functional imaging techniques, and lesion studies also occasionally induces clinical responses. In this study, we evaluated 25 patients with drug-refractory focal epilepsy by stereotactically implanting at least one electrode into the insular cortex using an oblique approach (transfrontal or transparietal). One hundred twenty-eight insular sites (each situated between two contiguous contacts within the same electrode) were examined within the gyral substructures. We located each stimulation site by fusing preimplantation three-dimensional (3D) magnetic resonance imaging (MRI) images with the postimplantation 3D computed tomography (CT) scans that revealed the electrode contacts. Sixty-seven stimulations induced at least one clinical response. Stimulation from within the insular cortex evoked 83 responses, without evidence of afterdischarge in the insular or extrainsular regions. We classified the principal responses as sensory (paresthesias and localized warm sensations), motor, pain, auditory, oropharyngeal, speech disturbances (including speech arrest and reduced voice intensity) and neurovegetative phenomena, such as facial reddening, generalized sensations of warmth or cold, hypogastric sensations, anxiety attacks, respiratory accelerations, sensations of rotation, and nausea. These findings may indicate a functional specificity for the insular gyri and show the need for exploring this structure during invasive presurgical evaluation of epileptic patients according to seizure manifestations.

Effects of biphasic current pulse frequency, amplitude, duration, and interphase gap on eye movement responses to prosthetic electrical stimulation of the vestibular nerve.

An implantable prosthesis that stimulates vestibular nerve branches to restore sensation of head rotation and vision-stabilizing reflexes could benefit individuals disabled by bilateral loss of vestibular (inner ear balance) function. We developed a prosthesis that partly restores normal function in animals by delivering pulse frequency modulated (PFM) biphasic current pulses via electrodes implanted in semicircular canals. Because the optimal stimulus encoding strategy is not yet known, we investigated effects of varying biphasic current pulse frequency, amplitude, duration, and interphase gap on vestibulo-ocular reflex (VOR) eye movements in chinchillas. Increasing pulse frequency increased response amplitude while maintaining a relatively constant axis of rotation. Increasing pulse amplitude (range 0- 325 μA) also increased response amplitude but spuriously shifted eye movement axis, probably due to current spread beyond the target nerve. Shorter pulse durations (range 28- 340 μs) required less charge to elicit a given response amplitude and caused less axis shift than longer durations. Varying interphase gap (range 25- 175 μs) had no significant effect. While specific values reported herein depend on microanatomy and electrode location in each case, we conclude that PFM with short duration biphasic pulses should form the foundation for further optimization of stimulus encoding strategies for vestibular prostheses intended to restore sensation of head rotation.

Current and Future Management of Bilateral Loss of Vestibular Sensation — An Update on the Johns Hopkins Multichannel Vestibular Prosthesis Project

Bilateral loss of vestibular sensation can disable individuals whose vestibular hair cells are injured by ototoxic medications, infection, Ménière's disease or other insults to the labyrinth including surgical trauma during cochlear implantation. Without input to vestibulo-ocular and vestibulo-spinal reflexes that normally stabilize the eyes and body, affected patients suffer blurred vision during head movement, postural instability, and chronic disequilibrium. While individuals with some residual sensation often compensate for their loss through rehabilitation exercises, those who fail to do so are left with no adequate treatment options. An implantable neuroelectronic vestibular prosthesis that emulates the normal labyrinth by sensing head movement and modulating activity on appropriate branches of the vestibular nerve could significantly improve quality of life for these otherwise chronically dizzy patients.This brief review describes the impact and current management of bilateral loss of vestibular sensation, animal studies supporting the feasibility of prosthetic vestibular stimulation, and a vestibular prosthesis designed to restore sensation of head rotation in all directions. Similar to a cochlear implant in concept and size, the Johns Hopkins Multichannel Vestibular Prosthesis (MVP) includes miniature gyroscopes to sense head rotation, a microcontroller to process inputs and control stimulus timing, and current sources switched between pairs of electrodes implanted within the vestibular labyrinth. In rodents and rhesus monkeys rendered bilaterally vestibulardeficient via treatment with gentamicin and/or plugging of semicircular canals, the MVP partially restores the vestibulo-ocular reflex for head rotations about any axis of rotation in 3-dimensional space. Our efforts now focus on addressing issues prerequisite to human implantation, including refinement of electrode designs and surgical technique to enhance stimulus selectivity and preserve cochlear function, optimization of stimulus protocols, and reduction of device size and power consumption.

Galvanic Vestibular Stimulation Combines with Earth-Horizontal Rotation in Roll to Induce the Illusion of Translation

Human head rotation in roll around an earth-horizontal axis constitutes a vestibular stimulus that, by its rotational component, acts on the semicircular canals (SCC) and that, by its tilt of the gravity vector, also acts on the otoliths. Galvanic vestibular stimulation (GVS) is thought to resemble mainly a rotation in roll. A superposition of sinusoidal GVS with a natural earth-horizontal roll movement was therefore applied in order to cancel the rotation effects and to isolate the otolith activation. By self-adjusting the amplitude and phase of GVS, subjects were able to minimize their sensation of rotation and to generate the perception of a linear translation. The final adjustments are in the range of a model that predicts SCC activation during natural rotations and GVS. This indicates that the tilt-translation ambiguity of the otoliths is resolved by SCC-otolith interaction. It is concluded that GVS might be able to cancel rotations in roll and that the residual tilt of the gravitoinertial force is possibly interpreted as a linear translation.

Retention of habituation of vestibulo-ocular reflex and sensation of rotation in humans

In humans, habituation of vestibulo-ocular reflex (VOR) by repeated caloric or rotational stimulation has been well documented. However, less attention has been directed to the effect of habituation on the sensation of self-rotation and little is known about the retention duration of vestibular habituation. To investigate these characteristics, subjects were exposed to ten sessions of angular velocity steps in yaw, with a chair rotating either alternatively in both CW and CCW directions (bidirectional protocol) or always in the same direction (unidirectional protocol), i.e., CW or CCW. The retention of habituation of VOR and sensation of rotation induced by both protocols was studied for a period up to 8 months following the end of the habituation protocols. There was a progressive decline in the VOR peak slow phase velocity and time constant throughout the sessions during both protocols. These parameters then followed an exponential recovery with a time constant of about 1 month. The duration of the sensation of rotation also habituated during repeated angular velocity steps, but it was shorter for both directions of stimulation, including after the unidirectional protocol. Sinusoidal VOR gain was not affected by vestibular habituation to velocity steps, but sinusoidal VOR phase showed an increase in phase lead at 0.02 and 0.04 Hz, which also returned to baseline values within about 1 month. We conclude that vestibular habituation is a long-lasting phenomenon. These results may be helpful for designing and scheduling the protocols for drug studies using crossover design, rehabilitation of balance disorder patients, and for the application of intermittent artificial gravity during space missions.

Visual Sensations of Roll Rotation During Complex Vestibular Stimulation

In aviation, vestibular-induced spatial disorientation is a significant cause of accidents. Recreating flight-like vestibular stimuli in simulators might be a means for training pilots to respond adequately in disorienting situations. Due to the physical constraints of land-based simulators, the question arises whether a given illusion may be created in different ways. For instance, is it possible to induce sensations of tilt by rotary stimuli? The present study concerns the relationship between sensations of rotation and tilt during complex vestibular stimulation. The visual sensation of roll rotation was quantified by means of a velocity-matching procedure. In a large gondola centrifuge eight subjects underwent four runs (2 G, 2 min) with different heading positions (forward, backward, centripetally, and centrifugally). The inclination of the gondola persistently corresponded with the vector sum of the Earth gravity force and the centrifugal force (60 degrees at 2 G). Thus, the semicircular canal stimulus in roll was combined in different ways with stimuli in yaw and pitch, as well as with an increasing or decreasing G vector. The magnitude of the responses was only dependent on the roll component of the stimulus. The gain, defined as the ratio between the response and the roll stimulus, was 7-10%. The responses decayed with a time constant ranging from 4 to 5.5 s. The visual sensation of roll rotation reflects the roll plane canal velocity stimulus independently of other stimulus components. This is in contrast to earlier findings on the sensation of changes in position (roll tilt).

Changes in the perceived head transversal plane and the subjective visual horizontal induced by Coriolis stimulation during gondola centrifugation

For studying the influence of the vertical semicircular canals on spatial orientation in roll, the subjective visual horizontal (SVH) and the subjective transversal plane of the head (STP) were measured in a situation where the vertical canals sense a roll-velocity stimulus while the otolith organs persistently signal that the head is upright in roll. During gondola centrifugation (resultant gravitoinertial force vector 2.5 G, gondola inclination 66 degrees) subjects were exposed to controlled rotational head movements (angular speed 27 degrees/s, magnitude 40 degrees) about the yaw (body z-) axis, produced by means of a motor-driven helmet. This causes a roll-plane Coriolis stimulus to the canals, while the otoliths persistently sense upright head position in roll. The subjects reported intense sensations of rotation and tilt in the roll plane. This was reflected in tilts of both the SVH and STP. The initial tilt of the SVH was 13.0 +/- 9.7 degrees (mean +/- S.D., n=10). The STP was changed in the opposite direction. The initial tilt was 23.8 +/- 12.2 degrees (mean +/- S.D., n=5). The changes in the SVH and STP were not of equal magnitude. A few subjects who had almost no deviations in the SVH showed pronounced tilts of the STP. The time constant for exponential decay of the tilts of the SVH and STP was on average approximately 1 minute. These findings indicate that a difference in activity of the vertical canals in the right versus left ear may cause substantial tilts of the SVH even if there is no asymmetry in the activity of the otolith system. Further, the canal stimulus may induce a tilt of the fundamental egocentric frame of reference.

Benign paroxysmal vertigo and migraine in children: epidemiological evidence

Background: Benign Paroxysmal Vertigo (BPV) is the unreal sensation of rotation of the individual or the environment. The cause of BPV of childhood is not known, but it may represent an early manifestation of migraine and is often regarded as a migraine equivalent.

Assessment of Vertigo

Vertigo is defined as a subjective sense of imbalance and includes unsteadiness as well as a sensation of rotation. Vertiginous symptoms may arise from defects in the labyrinth, the visual system, or the central nervous system, although in most patients presenting with balance problems, the lesion lies within the labyrinth or its central connections. The most important step in the diagnosis is an unhurried and detailed history, bearing in mind that many patients will have difficulty in describing their symptoms. A detailed neurological examination is usually unnecessary but one must examine the ears, cranial nerves, cerebellum, and balance function, and look for the presence of nystagmus. The common error of carrying out investigations in place of a detailed history is to be avoided. In many cases, investigations are not required at all, although it is the author’s practice to do a routine pure tone audiogram with basic assessment of speech discrimination. There is no indication for routine caloric testing, imaging or blood analysis, each of which should be carried out only when there are specific indications. In the routine clinical care of patients, it is only in exceptional situations that specialised vestibular testing is required, although these are often necessary in research projects.

視覚系と前庭系の相互作用による水平回転感覚の基礎特性

We investigated visual-vestibular interaction when a body that was passively rotated about its vertical axis while rotating vertical gratings were visually presented. A turntable, which generated a constant angular acceleration stimulated the semicircular canals and a head mounted display, provided an independent visual input. Vestibular stimulation ranged between 0.02 deg/s2 and 2.0 deg/s2. We found that visual image information was predominat when the visual image was presented and the body acceleration was less than 0.1 deg/s2. We also found that in the case of opposite direction between body rotation and visual image rotation, the estimated magnitude of a body rotation increased with the acceleration of visual image when the vestibular acceleration was between 0.1 deg/s2 and 1.0 deg/s2. These experimental findings can be used to develop a simulator or a display which can effectively produce a rotational sensation of the body.

空間識・シリーズ教育講座 １７．コリオリ刺激が誘起する回転感覚と錯覚

The sensation of rotation derived from the semicircular canal system during a Coriolis stimulus, or cross-coupled rotation, was estimated by an mechanical approach by giving some hypotheses and simplifications on the semicircular canal system. By solving an equation of motion of the endolymph during a Coriolis stimulus with a moderate time course, the rotating angle of the endolymph was obtained, and the sensation of rotation derived from each semicircular canal was estimated. Then, the sensation was integrated in the whole semicircular canal system, which was considered to be composed of three orthogonal semicircular canals. The sensation of rotation derived from the semicircular canal system comes into conflict with those from the otolithic and somatosensory system. The conflict causes an illusion such that the head rotates vertically while keeping inclination at a constant tilt angle. The nauseogenic severity of motion sickness caused by a Coriolis stimulus is enhanced in accordance with the integrated angle of rotation perceived by the illusion.

Dominance for vestibular cortical function in the non-dominant hemisphere.

The aim of this (15)O-labelled H(2)O bolus positron emission tomography (PET) study was to analyse the hemispheric dominance of the vestibular cortical system. Therefore, the differential effects of caloric vestibular stimulation (right or left ear irrigation with warm water at 44 degrees C) on cortical and subcortical activation were studied in 12 right-handed and 12 left-handed healthy volunteers. Caloric irrigation induces a direction-specific sensation of rotation and nystagmus. Significant regional cerebral blood flow increases were found in a network within both hemispheres, including the superior frontal gyrus/sulcus, the precentral gyrus and the inferior parietal lobule with the supramarginal gyrus. These areas correspond best to the cortical ocular motor centres, namely the prefrontal cortex, the frontal eye field and the parietal eye field, known to be involved in the processing of caloric nystagmus. Furthermore, distinct temporo-parietal activations could be separated in the posterior part of the insula with the adjacent superior temporal gyrus, the inferior parietal lobule and precuneus. These areas fit best to the human homologues of multisensory vestibular cortex areas identified in the monkey and correspond to the parieto-insular vestibular cortex (PIVC), the visual temporal sylvian area (VTS) and areas 7 and 6. Further cortical activations were seen in the anterior insula, the inferior frontal gyrus and anterior cingulum. The subcortical activation pattern in the putamen, thalamus and midbrain is consistent with the organization of efferent ocular motor pathways. Cortical and subcortical activation of the described areas was bilateral during monaural stimulation, but predominant in the hemisphere ipsilateral to the stimulated ear and exhibited a significant right hemispheric dominance for vestibular and ocular motor structures in right-handed volunteers. Similarly, a significant left hemispheric dominance was found in the 12 left-handed volunteers. Thus, this PET study showed for the first time that cortical and subcortical activation by vestibular caloric stimulation depends (i) on the handedness of the subjects and (ii) on the side of the stimulated ear. Maximum activation was therefore found when the non-dominant hemisphere was ipsilateral to the stimulated ear, i.e. in the right hemisphere of right-handed subjects during caloric irrigation of the right ear and in the left hemisphere of left-handed subjects during caloric irrigation of the left ear. The localization of handedness and vestibular dominance in opposite hemispheres might conceivably indicate that the vestibular system and its hemispheric dominance, which matures earlier during ontogenesis, determine right- or left-handedness.