scholarly journals Development of a conversion model between mechanical and electrical vestibular stimuli

2020 ◽  
Vol 123 (2) ◽  
pp. 548-559
Author(s):  
A. Chen ◽  
N. Khosravi-Hashemi ◽  
C. Kuo ◽  
J. K. Kramer ◽  
J.-S. Blouin
Keyword(s):  
Angular Velocity ◽  
Internal Representation ◽  
Step Change ◽  
Whole Body ◽  
Slow Phase ◽  
Bootstrap Analysis ◽  
Conversion Model ◽  
Vestibular Stimulus ◽  
Vestibular Afferents ◽  
Electrical Stimuli

The vestibular end-organs encode for linear and angular head accelerations in space contributing to our internal representation of self-motion. Activation of the vestibular system with transmastoid electrical current has recently grown in popularity; however, a direct relationship between electrically evoked and mechanically evoked vestibular responses remains elusive in humans. We have developed and tested a mechanical-to-electrical vestibular stimulus conversion model incorporating physiological activation of primary vestibular afferents identified in nonhuman primates. We compared ocular torsional responses between mechanical (chair rotation) and model-derived electrical (binaural-bipolar) stimuli in separate experiments for an angular velocity step change (±10 deg/s over 1 s, ±4-mA peak amplitude; n = 10) and multisine angular velocities (±10 deg/s, 9.7 mA peak to peak, 0.05–1 Hz; n = 5), respectively. Perception of whole body rotation ( n = 18) to our step-change stimuli was also evaluated. Ocular torsional slow-phase velocity responses between stimulation types were similar (paired two one-sided tests of equivalence: multiple P < 0.002; one-sample t test: P = 0.178) and correlated (Pearson’s coefficient: multiple P < 0.001). Bootstrap analysis of perceived angular velocity likewise showed similarity in perceptual decay dynamics. These data suggest that central processing between stimuli was similar, and our vestibular stimulus conversion model with a conversion factor of ∼0.4 mA per deg/s for an angular velocity step change can generate electrical stimuli that replicates dynamic vestibular activation elicited by mechanical whole body rotations. This proposed vestibular conversion model represents an initial framework for using electrical stimuli to generate mechanically equivalent activation of primary vestibular afferents for use in biomedical applications and immersive reality technologies. NEW & NOTEWORTHY With the growing popularity of electrical vestibular stimulation in biomedical and immersive reality applications, a direct conversion model between electrical and mechanical vestibular stimuli is needed. We developed a model to generate electrical stimuli mimicking the physiological activation of vestibular afferents evoked by mechanical rotations. Ocular and perceptual responses evoked by mechanical and model-derived electrical stimuli were similar, thus providing a critical first step toward generation of electrically induced vestibular responses that have a realistic mechanical equivalent.

Electrically evoked isokinetic plantar flexor torque in males

1987 ◽  
Vol 63 (4) ◽  
pp. 1499-1503 ◽  
Author(s):  
D. O. Thomas ◽  
M. J. White ◽  
G. Sagar ◽  
C. T. Davies
Keyword(s):  
Angular Velocity ◽  
Muscle Activation ◽  
Triceps Surae ◽  
Plantar Flexor ◽  
Velocity Data ◽  
Exponential Equation ◽  
Isometric Torque ◽  
The Mean ◽  
Electrical Stimuli ◽  
Male Subjects

The involuntary angle-specific isokinetic plantar flexor torques of seven male subjects aged 18–21 yr were measured using a Cybex II dynamometer (Lumex) modified by the addition of a strain-gauge load cell to improve the dynamic response of the instrument. Supramaximal electrical stimuli were used to evoke a maximal tetanic response from the triceps surae and ensure constant muscle activation at each angular velocity studied. Angle-specific torques were measured over a range (0.5–5.0 rad/s) of preset velocities, torque decreasing in a nonlinear manner with increasing angular velocity. The torque-velocity data was adequately described by an exponential equation of the form: V = a(e-1/b - e-Po/b) where V = velocity (rad/s), P = torque (N.m), Po = isometric torque (N.m), and a and b are constants. The mean intrasubject coefficient of variation of torque over the range of velocities studies was 7.9 +/- 1.88% (SD).

scholarly journals Responses of Primate Caudal Parabrachial Nucleus and Kölliker-Fuse Nucleus Neurons to Whole Body Rotation

2002 ◽  
Vol 88 (6) ◽  
pp. 3175-3193 ◽  
Author(s):  
Carey D. Balaban ◽  
David M. McGee ◽  
Jianxun Zhou ◽  
Charles A. Scudder
Keyword(s):  
Angular Velocity ◽  
Vertical Plane ◽  
Affective Responses ◽  
Macaca Nemestrina ◽  
Whole Body ◽  
Vertical Position ◽  
Limbic Cortex ◽  
Body Rotation ◽  
Spatial Tuning ◽  
Position Sensitive

The caudal aspect of the parabrachial (PBN) and Kölliker-Fuse (KF) nuclei receive vestibular nuclear and visceral afferent information and are connected reciprocally with the spinal cord, hypothalamus, amygdala, and limbic cortex. Hence, they may be important sites of vestibulo-visceral integration, particularly for the development of affective responses to gravitoinertial challenges. Extracellular recordings were made from caudal PBN cells in three alert, adult female Macaca nemestrina through an implanted chamber. Sinusoidal and position trapezoid angular whole body rotation was delivered in yaw, roll, pitch, and vertical semicircular canal planes. Sites were confirmed histologically. Units that responded during rotation were located in lateral and medial PBN and KF caudal to the trochlear nerve at sites that were confirmed anatomically to receive superior vestibular nucleus afferents. Responses to whole-body angular rotation were modeled as a sum of three signals: angular velocity, a leaky integration of angular velocity, and vertical position. All neurons displayed angular velocity and integrated angular velocity sensitivity, but only 60% of the neurons were position-sensitive. These responses to vertical rotation could display symmetric, asymmetric, or fully rectified cosinusoidal spatial tuning about a best orientation in different cells. The spatial properties of velocity and integrated velocity and position responses were independent for all position-sensitive neurons; the angular velocity and integrated angular velocity signals showed independent spatial tuning in the position-insensitive neurons. Individual units showed one of three different orientations of their excitatory axis of velocity rotation sensitivity: vertical-plane-only responses, positive elevation responses (vertical plane plus ipsilateral yaw), and negative elevation axis responses (vertical plane plus negative yaw). The interactions between the velocity and integrated velocity components also produced variations in the temporal pattern of responses as a function of rotation direction. These findings are consistent with the hypothesis that a vestibulorecipient region of the PBN and KF integrates signals from the vestibular nuclei and relay information about changes in whole-body orientation to pathways that produce homeostatic and affective responses.

scholarly journals Perceptual precision of passive body tilt is consistent with statistically optimal cue integration

2017 ◽  
Vol 117 (5) ◽  
pp. 2037-2052 ◽  
Author(s):  
Koeun Lim ◽  
Faisal Karmali ◽  
Keyvan Nicoucar ◽  
Daniel M. Merfeld
Keyword(s):  
Kalman Filter ◽  
Maximum Likelihood ◽  
Internal Representation ◽  
Body Tilt ◽  
Whole Body ◽  
Potential Contribution ◽  
Motion Direction ◽  
Filter Model ◽  
Ml Estimator ◽  
Roll Tilt

When making perceptual decisions, humans have been shown to optimally integrate independent noisy multisensory information, matching maximum-likelihood (ML) limits. Such ML estimators provide a theoretic limit to perceptual precision (i.e., minimal thresholds). However, how the brain combines two interacting (i.e., not independent) sensory cues remains an open question. To study the precision achieved when combining interacting sensory signals, we measured perceptual roll tilt and roll rotation thresholds between 0 and 5 Hz in six normal human subjects. Primary results show that roll tilt thresholds between 0.2 and 0.5 Hz were significantly lower than predicted by a ML estimator that includes only vestibular contributions that do not interact. In this paper, we show how other cues (e.g., somatosensation) and an internal representation of sensory and body dynamics might independently contribute to the observed performance enhancement. In short, a Kalman filter was combined with an ML estimator to match human performance, whereas the potential contribution of nonvestibular cues was assessed using published bilateral loss patient data. Our results show that a Kalman filter model including previously proven canal-otolith interactions alone (without nonvestibular cues) can explain the observed performance enhancements as can a model that includes nonvestibular contributions. NEW & NOTEWORTHY We found that human whole body self-motion direction-recognition thresholds measured during dynamic roll tilts were significantly lower than those predicted by a conventional maximum-likelihood weighting of the roll angular velocity and quasistatic roll tilt cues. Here, we show that two models can each match this “apparent” better-than-optimal performance: 1) inclusion of a somatosensory contribution and 2) inclusion of a dynamic sensory interaction between canal and otolith cues via a Kalman filter model.

Asymmetry of Vestibulo-Ocular Reflex in the Cat

1985 ◽  
Vol 93 (5) ◽  
pp. 597-600 ◽  
Author(s):  
John H. Anderson ◽  
Stephen L. Liston
Keyword(s):  
Eye Movements ◽  
Semicircular Canals ◽  
Whole Body ◽  
Slow Phase ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Vertical Semicircular Canals

Vertical eye movements were recorded in alert, restrained cats that were subjected to whole-body rotations which stimulated the vertical semicircular canals. The results showed a significant asymmetry between the upward and downward slow-phase eye movements, which suggests differences in the CNS processing of vertical canal inputs vis-à-vis the vestibulo-ocular reflex.

Adaptation of the vestibulo-ocular reflex, subjective tilt, and motion sickness to head movements during short-radius centrifugation

2003 ◽  
Vol 13 (2-3) ◽  
pp. 65-77
Author(s):  
Laurence R. Young ◽  
Kathleen H. Sienko ◽  
Lisette E. Lyne ◽  
Heiko Hecht ◽  
Alan Natapoff
Keyword(s):  
Motion Sickness ◽  
Body Position ◽  
Rest Period ◽  
Vertical Axis ◽  
Head Movements ◽  
Whole Body ◽  
Slow Phase ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex ◽  
Angular Velocities

Head movements made while the whole body is rotating at unusually high angular velocities (here with supine body position about an earth-vertical axis) result in inappropriate eye movements, sensory illusions, disorientation, and frequently motion sickness. We investigated the acquisition and retention of sensory adaptation to cross-coupled components of the vestibulo-ocular reflex (VOR) by asking eight subjects to make headturns while being rotated at 23 rpm on two consecutive days, and again a week later. The dependent measures were inappropriate vertical VOR, subjective tilt, and motion sickness in response to 90° yaw out-of-plane head movements. Motion sickness was evaluated during and following exposure to rotation. Significant adaptation effects were found for the slow phase velocity of vertical nystagmus, the reported magnitude of the subjective tilt experienced during head turns, and motion-sickness scores. Retention of adaptation over a six-day rest period without rotation occurred, but was not complete for all measures. Adaptation of VOR was fully maintained while subjective tilt was only partially maintained and motion-sickness scores continued to decrease. Practical implications of these findings are discussed with particular emphasis on artificial gravity, which could be produced in weightlessness by means of a short-radius (2 m) rotator.

Anterior canal neurons in cat vestibular nuclei have large phase leads during low frequency vertical axis pitch

2007 ◽  
Vol 16 (6) ◽  
pp. 245-256
Author(s):  
Sandra C. Brettler ◽  
James F. Baker
Keyword(s):  
Low Frequency ◽  
Vertical Axis ◽  
Vestibular Nuclei ◽  
Whole Body ◽  
Posterior Canal ◽  
Spatial Sensitivity ◽  
Ocular Reflex ◽  
Vestibular Afferents ◽  
Vestibulo Ocular Reflex ◽  
Anterior Canal

Vestibulo-ocular and second-order neurons in medial and superior vestibular nuclei of alert cats were identified by antidromic and orthodromic electrical stimulation, and their responses to whole body rotations were recorded in the dark. Neurons that had spatial sensitivity most closely aligned with the anterior canal (anterior canal neurons) were compared with neurons that had spatial sensitivity most closely aligned with the posterior canal (posterior canal neurons). Responses were recorded during low frequency earth-horizontal axis pitch rotations in the normal upright posture, and during earth-vertical axis pitch with the head and body lying on the left side. During upright pitch, response phases of anterior canal neurons slightly lagged those of posterior canal neurons or primary vestibular afferents, as previously reported. During on-side pitch, anterior canal neurons showed far greater phase leads with respect to head velocity than posterior canal neurons, primary vestibular afferents, or previously reported vestibulo-ocular reflex eye movements. These results provide challenges for vestibulo-ocular reflex models to incorporate central mechanisms for phase leads among the inputs to anterior canal neurons and to explain how the anterior canal neuron signals reported here combine with other signals to produce observed vestibulo-ocular reflex behavior.

THE DIURNAL VARIATION IN RENAL IODIDE EXCRETION RATE IN RABBITS

1976 ◽  
Vol 81 (3) ◽  
pp. 716-722 ◽  
Author(s):  
Steen Vadstrup ◽  
Jørgen Bojsen
Keyword(s):  
Diurnal Variation ◽  
Diurnal Rhythm ◽  
Continuous Monitoring ◽  
Excretion Rate ◽  
Whole Body ◽  
Slow Phase ◽  
Disappearance Rate ◽  
Rapid Phase ◽  
Excretion Rates ◽  
Clearance Technique

ABSTRACT The diurnal variation in renal iodide excretion rate was determined in unrestrained female rabbits by means of either a conventional clearance technique or a continuous monitoring of the whole body disappearance of iv injected 125I-iodide using an implanted Geiger-Müller detector. A distinct diurnal rhythm was detected in the disappearance rate of 125I-iodide. A slow disappearance rate occurred from 12 p. m. to 6 a. m. (darkness from 5 p. m. to 5 a. m.). The values of iodide excretion rate obtained by both methods were consistent like in humans with an excretion fraction of 0.3 for iodide in rabbits. In rabbits weighing 3-4 kg the renal iodide excretion rates were 5-7 ml/min during the rapid phase and 3-4 ml/min during the slow phase.

Behavioural and Mechanosensory Neurone Responses to Skin Stimulation in Leeches

1982 ◽  
Vol 96 (1) ◽  
pp. 143-160
Author(s):  
WILLIAM B. KRISTAN ◽  
STEPHEN J. McGIRR ◽  
GREGORY V. SIMPSON
Keyword(s):  
Sensory Input ◽  
The Body ◽  
Whole Body ◽  
Sensory Cells ◽  
Voltage Range ◽  
Behavioural Responses ◽  
Body Regions ◽  
Macrobdella Decora ◽  
Electrical Stimuli ◽  
P Cells

1. Behavioural responses to electrical stimulation of mechanosensory neurones were characterized in two species of leeches, Hirudo medicinalis and Macrobdella decora. 2. Depending upon the site and intensity of stimulation, the stimuli elicited one or a combination of five different responses: local bending, curling, shortening, whole-body bending or swimming. 3. The electrical threshold for activating identified mechanosensory neurones, T (touch) cells and P (pressure) cells, was the same in all regions of the body. 4. The voltage range over which the electrical stimuli produced progressively more mechanosensory impulses was the same as the range that produced different behavioural responses. 5. These results suggest that the T and P mechanosensory neurones provide the entire sensory input for all the behavioural responses. The production of different behavioural responses to stimuli of different intensities at the same location are attributable to different firing rates of the same sensory cells, and different responses to the same stimulus at different locations suggest different interneuronal targets for the T and P cells in different body regions.

Human ocular counter-rolling and roll tilt perception during off-vertical axis rotation after spaceflight

2008 ◽  
Vol 17 (5-6) ◽  
pp. 209-215
Author(s):  
Gilles Clément ◽  
Pierre Denise ◽  
Millard F. Reschke ◽  
Scott J. Wood
Keyword(s):  
Head Tilt ◽  
Internal Representation ◽  
Vertical Axis ◽  
Body Tilt ◽  
Whole Body ◽  
Otolith Organs ◽  
Otolith Function ◽  
Significant Difference ◽  
Axis Rotation ◽  
Roll Tilt

Ocular counter-rolling (OCR) induced by whole body tilt in roll has been explored after spaceflight as an indicator of the adaptation of the otolith function to microgravity. It has been claimed that the overall pattern of OCR responses during static body tilt after spaceflight is indicative of a decreased role of the otolith function, but the results of these studies have not been consistent, mostly due to large variations in the OCR within and across individuals. By contrast with static head tilt, off-vertical axis rotation (OVAR) presents the advantage of generating a sinusoidal modulation of OCR, allowing averaged measurements over several cycles, thus improving measurement accuracy. Accordingly, OCR and the sense of roll tilt were evaluated in seven astronauts before and after spaceflight during OVAR at 45°/s in darkness at two angles of tilt (10° and 20°). There was no significant difference in OCR during OVAR immediately after landing compared to preflight. However, the amplitude of the perceived roll tilt during OVAR was significantly larger immediately postflight, and then returned to control values in the following days. Since the OCR response is predominantly attributed to the shearing force exerted on the utricular macula, the absence of change in OCR postflight suggests that the peripheral otolith organs function normally after short-term spaceflight. However, the increased sense of roll tilt indicates an adaptation in the central processing of gravitational input, presumably related to a re-weighting of the internal representation of gravitational vertical as a result of adaptation to microgravity.

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