[Ontogeny of the properties of the cells of the visual cortex of the kitten].
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Action Potentials↗
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Results for “Motion Perception”
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P6 acupressure reduces symptoms of vection-induced motion sickness.
PURPOSE: The purpose of the study was to examine the effectiveness of P6 acupressure on nausea associated with visually-induced motion sickness. METHOD: There were 64 subjects randomly divided into 4 groups: P6 acupressure, dummy-point acupressure, sham P6 acupressure, and control. Each subject sat in an optokinetic drum for a 12-min baseline and 12-min drum rotation period. Subjects' electrogastrograms (EGG's) and subjective symptoms of motion sickness were obtained. RESULTS: The results indicated that the subjects in the P6 acupressure group reported significantly less nausea [F(3,60) = 8.16, p < 0.0001] during drum rotation period than those in the dummy-point acupressure, sham acupressure, and control groups. The scores for symptoms of motion sickness of the P6 acupressure group were significantly lower than those in the sham acupressure and control groups [F(3,60) = 3.49, p < 0.02]. Also, the subjects in the P6 acupressure group showed significantly less abnormal gastric myoelectric activity, tachyarrhythmia, than those in the sham acupressure and control groups [F(3,60) = 2.78, p < 0.04]. However, the subjects in the dummy-point acupressure group did not report significantly fewer symptoms and show less tachyarrhythmia than those in the sham acupressure and control groups. CONCLUSION: We conclude that P6 acupressure reduces the severity of symptoms of visually-induced motion sickness and gastric tachyarrhythmia.
Acupuncture Points↗
Gastric emptying and the symptoms of vection-induced nausea.
OBJECTIVES: To examine the hypothesis that nausea during vection arises directly from an underlying alteration in gastric motility. DESIGN: The simultaneous application of vection and assessment of gastric emptying of a liquid, non-nutrient test meal allowed the examination of the interaction between changes in gastric motility and symptoms. METHODS: Studies were conducted in 14 volunteers. Vection was induced by seating the subject inside a rotating circular drum, which was painted with vertical black and white stripes. In the control study (n = 8) the drum was not rotated. Gastric emptying was measured by gamma scintigraphy of a radiolabelled isosmotic saline test meal. RESULTS: Vection induced upper abdominal sensations (epigastric awareness) in 10 subjects, eight of whom subsequently reported nausea; autonomic symptoms of sweating and pallor were experienced by 12 subjects. Two subjects remained completely asymptomatic during vection. None of the subjects experienced any sensations during the control study. Gastric emptying was significantly delayed during vection (P < 0.01). There was a highly significant correlation between gastric emptying and the intensity of nausea. However, examination of the gastric emptying profiles did not support any direct association between altered gastrointestinal motor activity and symptoms. Two subjects with slowing of gastric emptying exhibited no nausea or upper abdominal symptoms, while another two experienced nausea when the underlying rate of gastric emptying was similar to that of the control period. CONCLUSIONS: The delay in gastric emptying of a liquid test meal induced by vection appears to be a variable epiphenomenon of nausea. A cause and effect relationship between gastric emptying and nausea therefore appears unlikely.
Adult↗
[The effects of optokinetic stimulation on gastric motility in man].
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Adult↗
Somatosensory motion after-effect following earth-horizontal rotation about the Z-axis: a new illusion.
During rotation about the Z-axos while recumbent one is exposed to a changing pattern of pressure cues over the body surface. If the body is only loosely padded in the experimental apparatus, then apparent motion of part of the body surface may be experienced sometime after rotation has been terminated. This somatosensory motion aftereffect of opposite sign is temporarily abolished if one looks at the affected body area, but is again re-experienced when the gaze is shifted elswhere. The similarity of this motion aftereffect to those contingent on vestibular and visual stimulation is discussed.
Humans↗
[Automatic motion analysis of gait in patients with Parkinson disease: effects of levodopa and visual stimulations].
Gait analysis of 13 patients affected by Parkinson's disease (PD) and 7 healthy elderly volunteers was performed with a fully automatic motion analyser. The recording included stride parameters for walking velocity, stride length, stride duration and swing time. Maximal amplitudes of rotation of the hip, knee and ankle were also recorded. The analysis was performed for the PD's patients before and after L-Dopa intake. All the patients walked with and without transversal stripes on the floor. The contrasting white lines were 45 cm apart. After medication, the stride length, the velocity and the swing phase duration were significantly increased. The movements around the hip, knee and ankle joints that were initially reduced, poorly increased after L-Dopa intake. When stripes were placed on the floor, no significant changes occurred for the overall group of patients. Seven parkinsonian patients did improve with visual guidance, increasing their stride length and their speed. Some rotations of hip and knee were also influenced by stripes. This sub-group of patients was characterized by older age, a slower walking velocity, a smaller stride length and a shorter swing time. We correlated the sensitivity to visual cues to the defect of the visual contrast sensitivity that has been established in PD by several recent works. Locomotion on the transverse lines might have produced a motion perception at a rate determined by the speed of the patient. For appropriate intervals between stripes, one can hypothesise that the resulting visual stimuli belonged to a range of spatio-temporal frequencies that are decreased in patients with PD.
Aged↗
Fast and slow feedback loops for the visual correction of spatial errors in a pointing task: a reappraisal.
Experimental evidence supporting the idea that central and peripheral vision play a distinctive role in the on-line visual guidance of reaching movements is reappraised. The central retina, highly sensitive for the discrimination of relative position cues, subserves the error-detecting mechanisms that encode the discrete rate of change of location of the moving hand relative to the stationary target, feeding the slow corrective feedback loops that allow the accurate homing in of the hand on the target. The peripheral retina, mainly sensitive for the detection of continuous motion cues, is swept by the image of the hand moving towards the fovea, which is itself strongly anchored to the target during the whole course of the movement, thus providing a directional error signal used for fast correction of the movement trajectory. This interpretation fits a two-system model of motion perception derived from psychophysical data. It also fits anatomical and physiological data concerning the central distribution of static and kinetic cues through two separate visual channels. However, the way in which reafferent visual information involved in both feedback loops is further conveyed to the control system of arm-hand movement remains largely unknown.
Animals↗
Motion sickness susceptibility to optokinetic rotation correlates to past history of motion sickness.
PURPOSE: This study investigated correlations between motion sickness susceptibility to a rotating optokinetic drum and past history of motion sickness. METHOD: There were 49 subjects who filled out a questionnaire on motion sickness history (MSH) who participated in the experiment. Each subject sat in an optokinetic drum for a 12-min baseline and a 12-min drum rotation period. Subjects' motion sickness symptoms (MSS) and electrogastrograms (EGG's) were measured. RESULTS: There were significant correlations between MSH scores and MSS scores during drum rotation (r = 0.5392, p < 0.001), and between MSH scores and EGG 4-9 cycles per minute (cpm) spectral intensity ratios between drum rotation and baseline periods (r = 0.5320, p < 0.001). Further analysis indicated that the mean MSS scores during the drum rotation period were 11.50 for the top 33% MSH scorers, 4.18 for the middle 34% MSH scorers, and 3.63 for the bottom 33% MSH scorers. The mean EGG 4-9 cpm spectral intensity ratios between drum rotation and baseline periods were 2.62 for the top 33% MSH scorers, 1.44 for the middle 34% MSH scorers, and 1.21 for the bottom 33% MSH scorers. CONCLUSION: These results indicated that past history of motion sickness correlates with severity of motion sickness provoked by optokinetic rotation.
Adult↗
The severity of nauseogenic effect of cross-coupled rotation is proportional to gyroscopic angular acceleration.
METHOD AND RESULTS: Subjects underwent cross-coupled rotation of the head (i.e., Coriolis stimuli) during which the upper body was tilted from side to side during horizontal rotation of the whole body about the Earth-vertical axis. In Experiment 1, the angle between the two axes of cross-coupled rotation was changed to vary the magnitude of gyroscopic angular acceleration without wide variations in Coriolis linear acceleration. The severity of nausea evoked by cross-coupled rotation stimuli varied relative to the magnitude of gyroscopic angular acceleration. It is noteworthy that nausea was not evoked unless gyroscopic angular acceleration was generated, even though Coriolis linear acceleration was equally induced. In Experiment 2, subjects tilted the upper body with or without restriction of head movement to a vertical plane during Earth-vertical axis rotation of the body at various angular velocities. The severity of evoked nausea was in direct proportion to angular velocity of body rotation irrespective of the restriction. CONCLUSION: These results indicated that the severity of nauseogenic effect of cross-coupled rotation is directly proportional to gyroscopic angular acceleration.
Acceleration↗
Effects of spatial frequency of a vertically striped rotating drum on vection-induced motion sickness.
PURPOSE: The present study investigated the effects of differential spatial frequencies of a vertically striped, horizontally rotating drum on the observer's frequency of eye nystagmus, perceived velocity of self-motion, and symptoms of motion sickness. METHODS AND RESULTS: Two experiments were conducted. In Experiment 1, each of 10 subjects viewed 1 min of an optokinetic rotating drum at the speed of 10 rpm covered with 6, 12, 24, 48, and 96 pairs of black and white stripes, presented in counterbalanced order. The results indicated that subjects perceived significantly stronger circular vection (p < 0.05) and generated significantly higher frequencies of eye nystagmus (p < 0.05) when they were viewing 24 pairs of black and white stripes than when they were viewing any of the other combinations of 6, 12, 48, or 96 black and white stripes. In Experiment 2, 100 highly susceptible subjects viewed 16 min of an optokinetic rotating drum covered with one of the five different numbers of black and white stripe pairs: 6, 12, 24, 48, and 96. The results indicated that subjects in the group viewing 24 moving contrasts perceived significantly stronger circular vection (p < 0.001), reported significantly more severe symptoms of motion sickness (p < 0.001), and showed significantly greater ratios of EGG 4-9 cycles per minute spectral intensity between drum rotation and baseline periods (p < 0.004) than those in the groups of viewing 6, or 96 moving contrasts. CONCLUSION: These results demonstrated that the severity of vection-induced motion sickness is affected by differential spatial frequencies of the stripes of the rotating drum and may be affected by number of horizontal eye movements.
Adolescent↗
Frequency effect of 0.35-1.0 Hz horizontal translational oscillation on motion sickness and the somatogravic illusion.
BACKGROUND: Low frequency translational oscillation can provoke motion sickness in land vehicles, ships and aircraft. HYPOTHESIS: Nauseogenicity should decrease towards the higher frequencies. METHODS: Some 12 subjects were exposed to horizontal sinusoidal motion (3.6 m.s-2 peak) at four different frequencies 0.35, 0.50, 0.70, and 1.00 Hz, at 1-week intervals, latin square order. Subjects were seated in the upright position; motion was through the head-body X-axis. Motion was stopped (motion endpoint) at moderate nausea or after 30 min. RESULTS: The proportion of subjects experiencing moderate nausea decreased towards the higher frequency: 9/12 at 0.35 Hz, 3/12 at 0.50 Hz, 0/12 at 0.70 Hz, and 2/12 at 1.00 Hz. The mean time to motion endpoint increased significantly (p < 0.001) towards the higher frequency: 17.4 min 0.35 Hz; 26.0 min 0.50 Hz; 30 min 0.70 Hz; 28.3 min 1.00 Hz. Differences between frequencies were significant (0.001 < p < 0.05) except for 0.70 Hz to 1.00 Hz. At all frequencies tested, horizontal stimuli were more nauseogenic than predicted by mathematical models based on the frequency and intensity of vertical oscillation. Somatogravic illusion (SGI) was reported by 9/12 subjects (mean illusory tilt angles 15.6 degrees forward, 14.1 degrees back). SGI tended to diminish at the higher frequencies, but there was no relationship between SGI and motion sickness. CONCLUSIONS: These results confirm previous findings (9), and furthermore indicate that horizontal X-axis translational oscillation has greatly reduced nauseogenic potential at frequencies greater than 0.5 Hz. A mathematical model is proposed to predict motion sickness intensity and incidence due to this stimulus, which may also be applicable to equivalent Y-axis motion.
Adult↗
The effect of optokinetic stimulation on daytime sleepiness.
This study examined the effect of optokinetic stimulation on objective sleepiness, as measured by the Multiple Sleep Latency Test (MSLT). The Nightcap, a portable sleep monitor, was used in a novel way to perform MSLTs, as well as record sleep in the home. Subjects wore the Nightcap for seven consecutive nights. On days 3 and 5 of the protocol, subjects came into the lab for an MSLT. On the experimental day, subjects underwent 10 minutes optokinetic stimulation (OKS), resulting in moderate motion sickness prior to each MSLT trial. Although subjects in the OKS condition reported significantly more drowsiness than controls, this did not result in significantly reduced sleep latencies.
Analysis of Variance↗
Unusual vestibular and visual input in human dynamic balance as a motion sickness susceptibility test.
BACKGROUND: Motion sickness (MS) is commonly thought to arise from a sensory conflict. However, few quantitative methods based on this theory are available to detect MS susceptibility. HYPOTHESIS: It was asked whether the standardized unusual stimulation of a single sensory channel under quantified dynamic balance conditions in man could elicit a sensory conflict and therefore trigger motion sickness (MS) METHODS: Vestibular and visual channels were stimulated by galvanic current and rotating prismatic glasses, respectively. The moving platform used to create the requirements for dynamic balance conditions was chosen not only to worsen the malaise but also to obtain an objective measurement of the balance consequences of the stimulations. RESULTS: Both vestibular and visual stimulation, applied separately, elicited MS-like symptoms (in 56% and 73% of subjects, respectively) and stereotyped balance reactions. A relationship was found between subjective MS-like symptoms and objective measurements of dynamic balance performance. Subjects sensitive to unusual vestibular messages differed from the others by a greater increase in the parameters indicating a difficulty of balance whereas subjects sensitive to unusual visual messages were recognized by the strategy they used to balance themselves. CONCLUSIONS: These results demonstrated that a sensory conflict can trigger MS-like symptoms. We conclude that the measured parameters of a global somatomotor activity, such as the dynamic balance task proposed here, could be useful for objectively detecting subjects predisposed to MS, for training them and testing the efficiency of anti-MS drugs.
Adult↗
Functional magnetic resonance imaging of early visual pathways in dyslexia.
We measured brain activity, perceptual thresholds, and reading performance in a group of dyslexic and normal readers to test the hypothesis that dyslexia is associated with an abnormality in the magnocellular (M) pathway of the early visual system. Functional magnetic resonance imaging (fMRI) was used to measure brain activity in conditions designed to preferentially stimulate the M pathway. Speed discrimination thresholds, which measure the minimal increase in stimulus speed that is just noticeable, were acquired in a paradigm modeled after a previous study of M pathway-lesioned monkeys. Dyslexics showed reduced brain activity compared with controls both in primary visual cortex (V1) and in several extrastriate areas, including area MT and adjacent motion-sensitive areas (MT+) that are believed to receive a predominant M pathway input. There was a strong three-way correlation between brain activity, speed discrimination thresholds, and reading speed. Subjects with higher V1 and MT+ responses had lower perceptual thresholds (better performance) and were faster readers. These results support the hypothesis for an M pathway abnormality in dyslexia and imply strong relationships between the integrity of the M pathway, visual motion perception, and reading ability.
Adult↗
Primary visual cortex activity along the apparent-motion trace reflects illusory perception.
The illusion of apparent motion can be induced when visual stimuli are successively presented at different locations. It has been shown in previous studies that motion-sensitive regions in extrastriate cortex are relevant for the processing of apparent motion, but it is unclear whether primary visual cortex (V1) is also involved in the representation of the illusory motion path. We investigated, in human subjects, apparent-motion-related activity in patches of V1 representing locations along the path of illusory stimulus motion using functional magnetic resonance imaging. Here we show that apparent motion caused a blood-oxygenation-level-dependent response along the V1 representations of the apparent-motion path, including regions that were not directly activated by the apparent-motion-inducing stimuli. This response was unaltered when participants had to perform an attention-demanding task that diverted their attention away from the stimulus. With a bistable motion quartet, we confirmed that the activity was related to the conscious perception of movement. Our data suggest that V1 is part of the network that represents the illusory path of apparent motion. The activation in V1 can be explained either by lateral interactions within V1 or by feedback mechanisms from higher visual areas, especially the motion-sensitive human MT/V5 complex.
Adult↗
Perception of rigid motion in depth from the optical deformations of shadows and occlusion boundaries.
Three experiments were designed to examine the abilities of observers to determine an object's 3-dimensional structure and motion from various types of optical deformations. Observers were required to discriminate whether pairs of moving ellipsoids were rotating rigidly about a single axis or nonrigidly about different axes that varied in slant. Discrimination thresholds were significantly influenced by whether the ellipsoids were intersecting or nonintersecting and whether they contained identifiable texture elements. Performance was unaffected by precession movements of the axis of rotation, by increasing the number of intersecting ellipsoids beyond 2, or by replacing the deforming silhouettes with the projected motions of cast shadows presented in isolation against a planar background. These findings indicate that observers can perceive structure from motion based on several different types of optical deformation, including the deformations of shadows and silhouettes that do not contain identifiable features on which most existing theoretical analyses are designed to operate.
Adult↗
The use of different features by the matching process in short-range motion.
The perception of the direction of motion in luminance kinematograms breaks down when the displacement exceeds a few element widths (this limit is called Dmax). When kinematograms whose elements differ only, in hue are used, motion can be seen but performance declines at smaller displacements. The short-range process, once thought to be only a luminance correlator, is thus able to use hue. If the size of Dmax indicates how well a feature stimulates the motion sensors, hue might be said to have an especially weak input to motion sensors. In order to find the relative potency of luminance and hue as bases of the short-range matching process, Dmax for these features was compared to those obtained for kinematograms whose elements differed in phase (T-phase or L-phase) or orientation (/or/). The matching process could use all the features tested. Luminance seems to be the preferred basis for motion matching, with hue and phase (a tie) yielding smaller Dmax and orientation the smallest.
Color Perception↗
Interactions between self-motion and depth perception in the processing of optic flow.
Moving and acting in a 3D environment requires the perception of its 3D structure. Vision is known to play a crucial role in the control of self-motion, particularly through the changes in the retinal image subsequent to movements of the observer. Reciprocally, signals related to self-motion can also influence our visual perception of 3D space. These interactions between 3D visual perception and self-motion, as demonstrated behaviourally, are now better understood thanks to the development of computational models for processing moving images. They also bear a particular interest in the context of the recent intensive exploration of the inferior parietal lobe (IPL) by neurophysiologists. The IPL is now firmly established as one site of interaction between 3D visual perception and motor control. The parallel between behaviour and neurophysiology leads to a set of crucial, yet unanswered, questions.
Humans↗