Sensorimotor aspects of high-speed artificial gravity: III. Sensorimotor adaptation

2003 ◽  
Vol 12 (5-6) ◽  
pp. 291-299
Author(s):  
Paul DiZio ◽  
James R. Lackner
Keyword(s):  
Side Effects ◽  
Coriolis Force ◽  
High Speed ◽  
Motor Adaptation ◽  
Vestibular Stimulation ◽  
Head Movements ◽  
Artificial Gravity ◽  
Slow Rotation ◽  
Movement Trajectory ◽  
Rotation Rates

As a countermeasure to the debilitating physiological effects of weightlessness, astronauts could live continuously in an artificial gravity environment created by slow rotation of an entire spacecraft or be exposed to brief daily "doses" in a short radius centrifuge housed within a non-rotating spacecraft. A potential drawback to both approaches is that head movements made during rotation may be disorienting and nauseogenic. These side effects are more severe at higher rotation rates, especially upon first exposure. Head movements during rotation generate aberrant vestibular stimulation and Coriolis force perturbations of the head-neck motor system. This article reviews our progress toward distinguishing vestibular and motor factors in side effects of rotation, and presents new data concerning the rates of rotation up to which adaptation is possible. We have studied subjects pointing to targets during constant velocity rotation, because these movements generate Coriolis motor perturbations of the arm but do not involve unusual vestibular stimulation. Initially, reaching paths and endpoints are deviated in the direction of the transient lateral Coriolis forces generated. With practice, subjects soon move in straighter paths and land on target once more. If sight of the arm is permitted, adaptation is more rapid than in darkness. Initial arm movement trajectory and endpoint deviations are proportional to Coriolis force magnitude over a range of rotation speeds from 5 to 20 rpm, and there is rapid, complete motor adaptation at all speeds. These new results indicate that motor adaptation to high rotation rates is possible. Coriolis force perturbations of head movements also occur in a rotating environment but adaptation gradually develops over the course of many head movements.

Vestibular habituation during repetitive complex stimulation: a study of transfer effects

1964 ◽  
Vol 19 (5) ◽  
pp. 1005-1015 ◽  
Author(s):  
Fred E. Guedry ◽  
William E. Collins ◽  
Ashton Graybiel
Keyword(s):  
Vestibular Function ◽  
Frontal Plane ◽  
Vestibular Stimulation ◽  
Head Movements ◽  
Residual Effects ◽  
Slow Rotation ◽  
Transfer Effects ◽  
Center Of Rotation ◽  
Static Tests ◽  
Rotation Direction

Thirty-two men were rotated at 7.5 rev/min while facing the center of the Pensacola slow rotation room for several hours. The men were seated 4 ft from the center of rotation; direction of rotation was toward the subject's left. During rotation, subjects were immobile except for series of measured head movements restricted to the frontal plane and to a particular quadrant of that plane for each subject. Nystagmus, illusory phenomena, and nausea were reduced by this procedure, but this habituation did not transfer to other forms of vestibular stimulation including that induced by head movements in an “unpracticed” quadrant of the same plane. Residual effects exhibited in “static tests” after the habituation program were primarily restricted to the practiced quadrant. habituation; nystagmus; vestibular function Submitted on January 15, 1964

Threshold-based vestibular adaptation to cross-coupled canal stimulation

2008 ◽  
Vol 17 (4) ◽  
pp. 171-181
Author(s):  
Carol C. Cheung ◽  
Heiko Hecht ◽  
Thomas Jarchow ◽  
Laurence R. Young
Keyword(s):  
Eye Movements ◽  
Side Effects ◽  
Angular Velocity ◽  
Motion Sickness ◽  
Head Movements ◽  
Body Tilt ◽  
Rotation Rates ◽  
Vestibular Adaptation ◽  
Carry Over

Prior experiments have demonstrated that people are able to adapt to cross-coupled accelerations associated with head movements while spinning at high rotation rates (e.g., 23 rpm or 138°/s). However, while adapting, subjects commonly experience serious side effects, such as motion sickness, non-compensatory eye movements, and strong and potentially disorienting illusory body tilt or tumbling sensations. In the present study, we investigated the feasibility of adaptation using a threshold-based method, which ensured that the illusory tilt sensations remained imperceptible or just barely noticeable. This was achieved by incrementally increasing the angular velocity of the horizontal centrifuge while supine subjects made repeated consistent yaw head turns. Incremental adaptation phases started at centrifugation speeds of 3 rpm. Centrifuge speed was slowly increased in steps of 1.5 rpm until a light illusory tilt was experienced. At the end of the incremental procedure, subjects were able to make head turns while rotating 14 rpm without experiencing illusory tilt. Moreover, motion sickness symptoms could be avoided and a limited carry over of the adaptive state to stronger stimulation at 23 rpm was found. The results are compared to prior studies which adapted subjects to super-threshold stimuli.

Adaptation to rotating artificial gravity environments

2003 ◽  
Vol 13 (4-6) ◽  
pp. 321-330
Author(s):  
James R. Lackner ◽  
Paul A. DiZio
Keyword(s):  
Motor Adaptation ◽  
Vestibular Function ◽  
Inertial Mass ◽  
Head Movements ◽  
Artificial Gravity ◽  
General Belief ◽  
Coriolis Forces ◽  
Long Time ◽  
Angular Velocities ◽  
The 1960S

A series of pioneering experiments on adaptation to rotating artificial gravity environments was conducted in the 1960s. The results of these experiments led to the general belief that humans with normal vestibular function would not be able to adapt to rotating environments with angular velocities above 3 or 4 rpm. By contrast, our recent work has shown that sensory-motor adaptation to 10~rpm can be achieved relatively easily and quickly if subjects make the same movement repeatedly. This repetition allows the nervous system to gauge how the Coriolis forces generated by movements in a rotating reference frame are deflecting movement paths and endpoints and to institute corrective adaptations. Independent mechanisms appear to underlie restoration of straight movement paths and of accurate movement endpoints. Control of head movements involves adaptation of vestibulo-collic and vestibulo-spinal mechanisms as well as adaptation to motor control of the head as an inertial mass. The vestibular adaptation has a long time constant and the motor adaptation a short one. Surprisingly, Coriolis forces generated by natural turning and reaching movements in our normal environment are typically larger than those elicited in rotating artificial gravity environments. They are not recognized as such because self-generated Coriolis forces during voluntary trunk rotation are perceptually transparent. After adaptation to a rotating environment is complete, the Coriolis forces generated by movements within it also become transparent and are not felt although they are still present.

Sensorimotor aspects of high-speed artificial gravity: I. Sensory conflict in vestibular adaptation

2003 ◽  
Vol 12 (5-6) ◽  
pp. 271-282 ◽  
Author(s):  
Erika L. Brown ◽  
Heiko Hecht ◽  
Laurence R. Young
Keyword(s):  
High Speed ◽  
Motor Coordination ◽  
Head Movements ◽  
Body Tilt ◽  
Sensory Conflict ◽  
Rotation Rates ◽  
Coriolis Effects ◽  
Gain Adaptation ◽  
Intersensory Conflict ◽  
Vertical Nystagmus

Short-radius centrifugation offers a promising and affordable countermeasure to the adverse effects of prolonged weightlessness. However, head movements made in a fast rotating environment elicit Coriolis effects, which seriously compromise sensory and motor processes. We found that participants can adapt to these Coriolis effects when exposed intermittently to high rotation rates and, at the same time, can maintain their perceptual-motor coordination in stationary environments. In this paper, we explore the role of inter-sensory conflict in this adaptation process. Different measures (vertical nystagmus, illusory body tilt, motion sickness) react differently to visual-vestibular conflict and adapt differently. In particular, proprioceptive-vestibular conflict sufficed to adapt subjective parameters and the time constant of nystagmus decay, while retinal slip was required for VOR gain adaptation. A simple correlation between the strength of intersensory conflict and the efficacy of adaptation fails to explain the data. Implications of these findings, which differ from existing data for low rotation rates, are discussed.

scholarly journals Neural Basis of Visually Guided Head Movements Studied With fMRI

2003 ◽  
Vol 89 (5) ◽  
pp. 2516-2527 ◽  
Author(s):  
Laurent Petit ◽  
Michael S. Beauchamp
Keyword(s):  
Eye Movements ◽  
Head Movement ◽  
Brain Activity ◽  
Posterior Part ◽  
Vestibular Stimulation ◽  
Head Movements ◽  
Oculomotor Control ◽  
Imaging Studies ◽  
Neural Basis ◽  
Temporoparietal Junction

We used event-related fMRI to measure brain activity while subjects performed saccadic eye, head, and gaze movements to visually presented targets. Two distinct patterns of response were observed. One set of areas was equally active during eye, head, and gaze movements and consisted of the superior and inferior subdivisions of the frontal eye fields, the supplementary eye field, the intraparietal sulcus, the precuneus, area MT in the lateral occipital sulcus and subcortically in basal ganglia, thalamus, and the superior colliculus. These areas have been previously observed in functional imaging studies of human eye movements, suggesting that a common set of brain areas subserves both oculomotor and head movement control in humans, consistent with data from single-unit recording and microstimulation studies in nonhuman primates that have described overlapping eye- and head-movement representations in oculomotor control areas. A second set of areas was active during head and gaze movements but not during eye movements. This set of areas included the posterior part of the planum temporale and the cortex at the temporoparietal junction, known as the parieto-insular vestibular cortex (PIVC). Activity in PIVC has been observed during imaging studies of invasive vestibular stimulation, and we confirm its role in processing the vestibular cues accompanying natural head movements. Our findings demonstrate that fMRI can be used to study the neural basis of head movements and show that areas that control eye movements also control head movements. In addition, we provide the first evidence for brain activity associated with vestibular input produced by natural head movements as opposed to invasive caloric or galvanic vestibular stimulation.

Kinematics of Tongue Projection in Chamaeleo Oustaleti

1991 ◽  
Vol 159 (1) ◽  
pp. 109-133 ◽  
Author(s):  
PETER C. WAINWRIGHT ◽  
DAVID M. KRAKLAU ◽  
ALBERT F. BENNETT
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Maximum Velocity ◽  
Head Movements ◽  
Florida State University ◽  
State University ◽  
Maximum Acceleration ◽  
Related Family ◽  
High Speed Cinematography ◽  
Tongue Movements

The kinematics of prey capture by the chamaeleonid lizard Chamaeleo oustaleti were studied using high-speed cinematography. Three feeding sequences from each of two individuals were analyzed for strike distances of 20 and 35 cm, at 30°C. Ten distances and angles were measured from sequential frames beginning approximately 0.5 s prior to tongue projection and continuing for about 1.0 s. Sixteen additional variables, documenting maximum excursions and the timing of events, were calculated from the kinematic profiles. Quantified descriptions of head, hyoid and tongue movements are presented. Previously unrecognized rapid protraction of the hyobranchial skeleton simultaneously with the onset of tongue projection was documented and it is proposed that this assists the accelerator muscle in powering tongue projection. Acceleration of the tongue occurred in about 20ms, reaching a maximum acceleration of 486 m s−2 and maximum velocity of 5.8m s−1 in 35 cm strikes. Deceleration of the tongue usually began within 5 ms before prey contract and the direction of tongue movement was reversed within 10 ms of prey contact. Retraction of the tongue, caused by shortening of the retractor muscles, reached a maximum velocity of 2.99 ms−1 and was complete 330 ms after prey contact. Projection distance influences many aspects of prey capture kinematics, particularly projection time, tongue retraction time and the extent of gape and head movements during tongue retraction, all of which are smaller in shorter feedings. Though several features of the chameleon strike have apparently been retained from lizards not capable of ballistic tongue projection, key differences are documented. Unlike members of a related family, the Agamidae, C. oustaleti uses no body lunge during prey capture, exhibits gape reduction during tongue projection and strongly depresses the head and jaws during tongue retraction. Note: Present address: Department of Biological Sciences, Florida State University, Tallahassee, FL 32306, USA.

scholarly journals The vestibular-related frontal cortex and its role in smooth-pursuit eye movements and vestibular-pursuit interactions

2006 ◽  
Vol 16 (1-2) ◽  
pp. 1-22 ◽  
Author(s):  
Junko Fukushima ◽  
Teppei Akao ◽  
Sergei Kurkin ◽  
Chris R.S. Kaneko ◽  
Kikuro Fukushima
Keyword(s):  
Eye Movements ◽  
Frontal Cortex ◽  
Smooth Pursuit ◽  
Vestibular Stimulation ◽  
Target Motion ◽  
Head Movements ◽  
Image Motion ◽  
Target Velocity ◽  
Eye Velocity ◽  
Pursuit Neurons

In order to see clearly when a target is moving slowly, primates with high acuity foveae use smooth-pursuit and vergence eye movements. The former rotates both eyes in the same direction to track target motion in frontal planes, while the latter rotates left and right eyes in opposite directions to track target motion in depth. Together, these two systems pursue targets precisely and maintain their images on the foveae of both eyes. During head movements, both systems must interact with the vestibular system to minimize slip of the retinal images. The primate frontal cortex contains two pursuit-related areas; the caudal part of the frontal eye fields (FEF) and supplementary eye fields (SEF). Evoked potential studies have demonstrated vestibular projections to both areas and pursuit neurons in both areas respond to vestibular stimulation. The majority of FEF pursuit neurons code parameters of pursuit such as pursuit and vergence eye velocity, gaze velocity, and retinal image motion for target velocity in frontal and depth planes. Moreover, vestibular inputs contribute to the predictive pursuit responses of FEF neurons. In contrast, the majority of SEF pursuit neurons do not code pursuit metrics and many SEF neurons are reported to be active in more complex tasks. These results suggest that FEF- and SEF-pursuit neurons are involved in different aspects of vestibular-pursuit interactions and that eye velocity coding of SEF pursuit neurons is specialized for the task condition.

Sensorimotor aspects of high-speed artificial gravity: II. The effect of head position on illusory self motion

2003 ◽  
Vol 12 (5-6) ◽  
pp. 283-289
Author(s):  
Fred W. Mast ◽  
Nathaniel J. Newby ◽  
Laurence R. Young
Keyword(s):  
Healthy Subjects ◽  
Horizontal Plane ◽  
High Speed ◽  
Semicircular Canals ◽  
Vertical Axis ◽  
Head Position ◽  
Artificial Gravity ◽  
Axis Of Rotation ◽  
Self Motion

The effects of cross-coupled stimuli on the semicircular canals are shown to be influenced by the position of the subject's head with respect to gravity and the axis of rotation, but not by the subject's head position relative to the trunk. Seventeen healthy subjects made head yaw movements out of the horizontal plane while lying on a horizontal platform (MIT short radius centrifuge) rotating at 23 rpm about an earth-vertical axis. The subjects reported the magnitude and duration of the illusory pitch or roll sensations elicited by the cross-coupled rotational stimuli acting on the semicircular canals. The results suggest an influence of head position relative to gravity. The magnitude estimation is higher and the sensation decays more slowly when the head's final position is toward nose-up (gravity in the subject's head x-z-plane) compared to when the head is turned toward the side (gravity in the subject's head y-z-plane). The results are discussed with respect to artificial gravity in space and the possible role of pre-adaptation to cross-coupled angular accelerations on earth.

scholarly journals Angular momentum transport in massive stars and natal neutron star rotation rates

2019 ◽  
Vol 488 (3) ◽  
pp. 4338-4355 ◽  
Author(s):  
Linhao Ma ◽  
Jim Fuller
Keyword(s):  
Angular Momentum ◽  
Massive Stars ◽  
Baroclinic Instability ◽  
Core Collapse ◽  
Slow Rotation ◽  
Low Mass Stars ◽  
Rotation Rates ◽  
Rotation Periods ◽  
Low Mass ◽  
Binary Evolution

Abstract The internal rotational dynamics of massive stars are poorly understood. If angular momentum (AM) transport between the core and the envelope is inefficient, the large core AM upon core-collapse will produce rapidly rotating neutron stars (NSs). However, observations of low-mass stars suggest an efficient AM transport mechanism is at work, which could drastically reduce NS spin rates. Here, we study the effects of the baroclinic instability and the magnetic Tayler instability in differentially rotating radiative zones. Although the baroclinic instability may occur, the Tayler instability is likely to be more effective for AM transport. We implement Tayler torques as prescribed by Fuller, Piro, and Jermyn into models of massive stars, finding they remove the vast majority of the core’s AM as it contracts between the main-sequence and helium-burning phases of evolution. If core AM is conserved during core-collapse, we predict natal NS rotation periods of $P_{\rm NS} \approx 50\!-\!200 \, {\rm ms}$, suggesting these torques help explain the relatively slow rotation rates of most young NSs, and the rarity of rapidly rotating engine-driven supernovae. Stochastic spin-up via waves just before core-collapse, asymmetric explosions, and various binary evolution scenarios may increase the initial rotation rates of many NSs.

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