[Phase correlation of cupular and otolithic reactions and their interrelation with the development of motion sickness].
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Coriolis Force↗
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Some contributions of I.E. Purkynĕ to the visual physiology.
In the research of binocular vision J. E. Purkynĕ pointed out the role of retinal corresponding areas. He observed binocular interaction of pressure phosphenes elicited in them and the fusion of images projected on the corresponding foveal areas even in eyes with artificial divergency. For the first time he proposed the examination of visual fields (perimetry) in several planes and he also introduced the colour perimetry. Purkynĕ analyzed profoundly the different functions of direct (foveal) and indirect (peripheral) vision. In indirect vision he anticipated the modern concept of the useful field of view. Of fundamental importance was Purkynĕ's research of the strategy and different types of ocular movements. In analysis of motion perception, he evolved the hypothesis of "general sense of space" which is very close to modern feed-back conception of "corollary discharge".
Czechoslovakia↗
[Effects of visual field stabilization on the behavior of automobile drivers: visuo-vestibular model trials].
Postural changes of body equilibrium on a moving force plate were examined for sinusoidal movements, saccades and frequency whilst different stimuli were applied under various visual conditions. If a dynamic stimulus was used, the stabilization of vision shows a distinct visual-vestibular conflict which provokes postural disequilibrium. This is the cause of motion sickness during car driving. This disequilibrium is also the cause of the motor insecurity experienced during walking and reading at the same time.
Adult↗
Vision therapy as a treatment for motion sickness.
A case of visually-induced motion sickness (VIMS) is presented. The patient underwent a program of dynamic adaptive vision therapy which relieved her symptoms of motion sickness. Symptoms of VIMS may include photophobia, an inability to read in a moving auto, and nausea, dizziness, headache, eye strain and anxiety following provocative visual stimuli. The neural mismatch theory is discussed.
Adult↗
The central vestibular system.
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Abducens Nerve↗
Otolith tilt-translation reinterpretation following prolonged weightlessness: implications for preflight training.
Observations with three astronauts yielded two major findings. First, perceived self-motion during sinusoidal roll differed immediately postflight from preflight. Between 70 and 150 min after landing, roll was perceived primarily as linear translation. Secondly, more horizontal eye movement was elicited by roll stimulation immediately postflight relative to both preflight and later postflight observations. These results support an "otolith tilt-translation reinterpretation" hypothesis, which has clear implications for understanding astronaut reports of space motion sickness during the early period of orbital flight. A proposal for "prophylactic adaptation training" which may provide preflight adaptation to weightlessness, derives from this research.
Adaptation, Physiological↗
[Motion sickness (author's transl)].
A short introduction to motion sickness is followed by a historical survey of the various theories, with special reference to those concerning the inner ear. The symptomatology and the consequences of the disease are discussed. Prevention and therapy are considered.
Adaptation, Physiological↗
[Color properties of the receptive fields of visual cortex neurons in the squirrel].
The colour-sensitive properties of the visual cortex neurons were studied in the squirrel. All the neurons responded to achromatic, green and blue visual stimuli; responses to red stimuli were slight or absent. According to responses to patterned visual stimuli the neurons were classified as non-selective, directionally-selective and orientation-selective (simple and complex). No colour-opponent properties were revealed in any of these neuronal groups: neuronal responses were qualitatively the same to achromatic, green and blue stimuli, and the receptive fields organization was independent of the stimulus colour. These data are discussed with respect to the fact of presence of colour-opponent cells in the retina and lateral geniculate nucleus of squirrel.
Animals↗
Motion sickness--key to neurobiologic variation.
Individual variation in motion sickness susceptibility correlates with a wide variety of perceptual, cognitive, and personality variables suggesting that it may be a unique index of individual difference in fundamental mechanisms of the orientation process. Data from a large ongoing clinical study involving over 1,500 psychiatric inpatients indicate a clear-cut association between a number of the MMPI scales (including Social Isolation, Ego Strength and Schizophrenia) and motion sickness susceptibility. Marked difference across the motion sickness susceptibility spectrum in the condition on discharge of lithium and antidepressant treated patients was also found, when compared to other drug therapies, suggesting specific drug responses by the motion sick group.
Ego↗
Self-motion magnitude estimation during linear oscillation: changes with head orientation and following fatigue.
Two types of experiments concerning estimated magnitude of self-motion during exposure to linear oscillation on a parallel swing are described in this paper. Experiment I examined changes in magnitude estimation as a function of variation of the subject's head orientation, and Experiments II a, II b, and II c assessed changes in magnitude estimation performance following exposure to sustained, "intense" linear oscillation (fatigue-inducing stimulation). The subjects' performance was summarized employing Stevens' power law (R = k . Sn, where R is perceived self-motion magnitude, k is a constant, S is amplitude of linear oscillation, and n is an exponent). The results of Experiment I indicated that the exponents, n, for the magnitude estimation functions varied with head orientation and were greatest when the head was oriented 135 degrees off the vertical. In Experiments II a-c, the magnitude estimation function exponents were increased following fatigue. Both types of experiments suggest ways in which the vestibular system's contribution to a spatial orientation perceptual system may vary. This variability may be a contributing factor to the development of pilot/astronaut disorientation and may also be implicated in the occurrence of motion sickness.
Acceleration↗
[Detector neurons of the visual cortex of the chipmunk].
Three functional classes of neurons are described in the Siberian chipmunk visual cortex: neurons nonselective to movement direction, movement-direction-selective neurons and orientation-selective neurons. Nonselective and direction-selective neurons showed maximum adaptiveness at high speeds of movement: 100-500 degrees/s and more. Most of orientation-selective neurons were maximally activated at speeds 10-50 degrees/s. For all neuronal classes a clear-cut correlation between selectivity and movement speed as well as pattern of responses to stationary stimuli in the receptive field were found. The data obtained allowed a division of the neurons into two groups: phasically-fast and tonically-slow with predominance of the first group.
Animals↗
[Functional organization of the receptive fields of frog retina class I ganglion cells].
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Adaptation, Physiological↗
[Space-time organization of neuronal activity in the frog tectum and its transformation in response to different visual stimuli].
The space and time organization of neuronal activity was studied in the frog tectum opticum under the action of different visual stimuli. It is shown that inhibition plays an important role in neuronal reactions. It is suggested that differences in the space time parameters of neuronal activity reflect differences in visual signals which bring optic information from the retina.
Animals↗
[Squirrel visual cortex detector neurons discriminating the contours and rapid movements of visual stimuli].
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Animals↗
Vision and sports: a review of the literature.
The basis for training visual abilities to enhance sports performance is explored. Optometric intervention in sports assumes the following statements to be true: 1. Athletes have better visual abilities than non-athletes and better athletes have better visual abilities than the poorer athletes, 2. Visual abilities are trainable, and 3. Visual training is transferable to the performance of the athlete. The literature demonstrates that athletes have better visual abilities than non-athletes. Studies have shown this to be true in the following areas of vision: Larger extent of visual fields, larger fields of recognition (peripheral acuity), larger motion perception fields, lower amounts of heterophoria at near and far, more consistent simultaneous vision, more accurate depth perception, better dynamic visual acuity, and better ocular motilities. The literature also shows that all of the above skills are trainable. Two studies are cited that support the belief that visual training is transferable to athletic performance but they suffer from inadequate experimental design.
Adolescent↗
A comparison of some effects of three antimotion sickness drugs on nystagmic responses to angular accelerations and to optokinetic stimuli.
While the basic efficacy of antimotion sickness drugs is rooted in the reduction of motion sickness symptoms, adverse side effects are important practical considerations of their usage in aviation. This study examined the influence of three established antimotion sickness drugs on nystagmic eye movement responses to angular acceleration (whole-body movement) with vision either permitted or denied, and to optokinetic stimulation (visual field movement). Dimenhydrinate and promethazine hydrochloride, particularly at higher dose levels, reduced optokinetic nystagmus, thereby making less accurate the following ability of the eye. During whole-body motion in darkness, there was little placebo-drug difference in the vestibular response under alert conditions; under relaxed conditions, dimenhydrinate and promethazine hydrochloride produced significant declines in the vestibular eye movements. These same drugs also interfered with the ability of the individual to fixate adequately on a visual task during motion. Subjects who received a combination of promethazine plus d-amphetamine were able to suppress vestibular eye movements and maintain good visual fixation under the task condition. Thus, the effect of a drug on nystagmus may be a poor indicator of its value in preventing motion sickness. Moreover, assessments of antimotion sickness drugs for many practical situations should include, as a possible adverse side effect, the inability to maintain visual fixation during motion.
Acceleration↗
[Functional characteristics of visual cortex neurons in the squirrel].
The main functional classes of neurons in the squirrel visual cortex are described. The following classes were revealed on the basis of the receptive field organization and the pattern of response to visual stimuli: direction-non-selective neurons (14%), direction-selective neurons (30%), orientation-selective neurons (49%); 7% of neurons were unclassified. Direction-selective neurons and some non-selective ones were specifically sensitive to high speed of the stimulus movement (hundreds deg/s). Orientation-selective neurons differed in the degree of on- and off-zones overlapping; they may include analogues of simple and complex neurons.
Animals↗
Does image movement have a special nature for neurons in the cat's striate cortex?
The question of whether a moving image is especially effective for stimulating visual neurons was studied in the striate cortex of the cat. Receptive fields (RFs) of simple and complex neurons were stimulated with optimally oriented bright and dark bars that either moved smoothly or were presented statically at an array of positions across the RF. A linear prediction of responses to the smooth movement was calculated by superposition of the responses to stationary presentation of these bar stimuli. A comparison between responses to actual movement and their prediction showed that the relative effectiveness of a moving stimulus decreases with speed. Effects of "conditioning" stimuli and nitrous oxide anesthesia were also studied. Both simple and complex units exhibited on average slightly lower than predicted responses for both bright and dark bars, even when they moved in the preferred direction of the unit. Movement in the opposite direction usually elicited even lower response levels, suggesting nonlinear suppression. These results imply that a moving image has no special efficacy for visual neurons but rather that it has a special propensity to elicit suppression when it moves in the nonpreferred (null) direction of a neuron.
Animals↗