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PubMed2005

Ulnocarpal impaction syndrome restricts even midcarpal range of motion.

Ulnocarpal impaction syndrome is believed to be caused by abutment between the ulna and the ulnar carpus. We measured radiocarpal and midcarpal ranges of motion in 40 patients with ulnocarpal impaction syndrome by radiographic motion studies. The results showed that the radiocarpal and midcarpal ranges of motion were equally restricted in the affected wrist compared with the unaffected wrist. Therefore, motion of the radiocarpal joint and midcarpal joint contributed equally to total wrist motion bilaterally. No correlation between ulnar variance and the contribution of radiocarpal motion to overall wrist motion was found. Restriction of wrist motion in ulnocarpal impaction syndrome is not caused directly by abutment between the ulna and ulnar carpus, but a satisfactory explanation for restricted motion is still lacking.

Adult↗
PubMed1991

Effects of ginger on motion sickness susceptibility and gastric function.

This study was designed to evaluate the antimotion sickness activity of ginger root (Zingiber officinale) and to characterize the effects of ginger on gastric function. Twenty-eight human volunteers participated in the project. Subjects made timed head movements in a rotating chair until they reached an endpoint of motion sickness short of vomiting (malaise III or M-III). Each subject was tested with either ginger or scopolamine and a placebo. A substance was judged to possess antimotion sickness activity if it allowed a greater number of head movements compared to placebo control. Gastric emptying of a liquid was measured by nuclear medicine techniques in normal and motion sick subjects. Gastric electrical activity was monitored by cutaneous (surface) electrodes positioned over the abdominal area. Powder ginger (whole root, 500 or 1,000 mg) or fresh ginger root (1,000 mg) provided no protection against motion sickness. In contrast, subjects performed an average of 147.5 more head movements (p less than 0.01) after scopolamine (0.6 mg p.o.) than after placebo. The rate of gastric emptying was significantly (p less than 0.05) slowed when tested immediately after M-III but was inhibited less when tested 15 min after M-III. Powdered ginger (500 mg) had no effect on gastric emptying in normal or motion-sick subjects. Gastric motility was also changed during motion sickness. The frequency of the electrogastrogram (EGG) was increased after M-III (tachygastria) and the normal increase in EGG amplitude after liquid ingestion was reduced in motion sick subjects. Although powdered ginger (500 mg) partially inhibited tachygastria in motion sickness, it did not enhance the EGG amplitude in motion sick subjects. We conclude that ginger does not possess antimotion sickness activity, nor does it significantly alter gastric function during motion sickness.

Adolescent↗
PubMed1996

A theory of the visual motion coding in the primary visual cortex.

This paper demonstrates that much of visual motion coding in the primary visual cortex can be understood from a theory of efficient motion coding in a multiscale representation. The theory predicts that cortical cells can have a spectrum of directional indices, be tuned to different directions of motion, and have spatiotemporally separable or inseparable receptive fields (RF). The predictions also include the following correlations between motion coding and spatial, chromatic, and stereo codings: the preferred speed is greater when the cell receptive field size is larger, the color channel prefers lower speed than the luminance channel, and both the optimal speeds and the preferred directions of motion can be different for inputs from different eyes to the same neuron. These predictions agree with experimental observations. In addition, this theory makes predictions that have not been experimentally investigated systematically and provides a testing ground for an efficient multiscale coding framework. These predictions are as follows: (1) if nearby cortical cells of a given preferred orientation and scale prefer opposite directions of motion and have a quadrature RF phase relationship with each other, then they will have the same directional index, (2) a single neuron can have different optimal motion speeds for opposite motion directions of monocular stimuli, and (3) a neuron's ocular dominance may change with motion direction if the neuron prefers opposite directions for inputs from different eyes.

Color Perception↗
PubMed2002

Isotropic integration of binocular disparity and relative motion in the perception of three-dimensional shape.

Richards (1985) showed that veridical three-dimensional shape may be recovered from the integration of binocular disparity and retinal motion information, but proposed that this integration may only occur for horizontal retinal motion. Psychophysical evidence supporting the combination of stereo and motion information is limited to the case of horizontal motion (Johnston et al., 1994), and has been criticised on the grounds of potential object boundary cues to shape present in the stimuli. We investigated whether veridical shape can be recovered under more general conditions. Observers viewed cylinders that were defined by binocular disparity, two-frame motion or a combination of disparity and motion, presented at simulated distances of 30 cm, 90 cm or 150 cm. Horizontally and vertically oriented cylinders were rotated about vertical and horizontal axes. When rotation was about the cylinder's own axis, no boundary cues to shape were introduced. Settings were biased for the disparity and two-frame motion stimuli, while more veridical shape judgements were made under all conditions for combined cue stimuli. These results demonstrate that the improved perception of three-dimensional shape in these stimuli is not a consequence of the presence of object boundary cues, and that the combination of disparity and motion is not restricted to horizontal image motion.

Cues↗
PubMed1986

Form from motion parallax and form from luminance contrast: vernier discrimination.

UNLABELLED: Some objects are perfectly camouflaged when stationary, but are clearly visible when moving; the boundaries of such an object are defined entirely by motion parallax. Little is known about the eye's ability to make spatial discriminations between motion-defined objects. In this study, subjects viewed a pseudo-random pattern of dots within which a camouflaged bar was made visible by relative motion of dots. Vernier acuity for the motion-defined bar was 27-45 sec arc for three subjects, much less than the interdot separation of 360 sec arc, much less than the 2 deg receptive field size for motion, and comparable with the foveal intercone separation of 30 sec arc. It is proposed that an opponent-orientation process and an opponent-position process can both contribute to vernier judgements for motion-defined objects. Real-world motion contrast commonly confounds the following cues for figure-ground segregation: (1) different texture velocities on either side of the figure's boundary; (2) in any given time interval, texture in figure and ground moves different distances; and (3) texture continually appears and disappears along the figure's boundary. When cues (2) and (3) were eliminated, thus ensuring figure-ground segregation was achieved entirely by motion-sensitive neural elements, vernier acuity was 44 +/- 5 sec arc compared with 36 +/- 8 sec arc for a dotted bar defined by luminance contrast. CONCLUSION: Vernier acuity for a dotted bar whose boundary was defined entirely by motion-sensitive neural elements was similar to vernier acuity for a dotted bar whose boundary was defined by luminance contrast.

Contrast Sensitivity↗
PubMed1989

Motion: the long and short of it.

Several authors have proposed that motion is analyzed by two separate processes: short-range and long-range. We claim that the differences between short-range and long-range motion phenomena are a direct consequence of the stimuli used in the two paradigms and are not evidence for the existence of two qualitatively different motion processes. We propose that a single style of motion analysis, similar to the well known Reichardt and Marr-Ullman motion detectors, underlies all motion phenomena. Although there are different detectors of this type specialized for different visual attributes (namely first-order and second-order stimuli), they all share the same mode of operation. We review the studies of second-order motion stimuli to show that they share the basic phenomena observed for first-order stimuli. The similarity across stimulus types suggests, not parallel streams of motion extraction, one short-range and passive and the other long-range and intelligent, but a concatenation of a common mode of initial motion extraction followed by a general inference process.

Adaptation, Ocular↗
PubMed2002

Decomposing biological motion: a framework for analysis and synthesis of human gait patterns.

Biological motion contains information about the identity of an agent as well as about his or her actions, intentions, and emotions. The human visual system is highly sensitive to biological motion and capable of extracting socially relevant information from it. Here we investigate the question of how such information is encoded in biological motion patterns and how such information can be retrieved. A framework is developed that transforms biological motion into a representation allowing for analysis using linear methods from statistics and pattern recognition. Using gender classification as an example, simple classifiers are constructed and compared to psychophysical data from human observers. The analysis reveals that the dynamic part of the motion contains more information about gender than motion-mediated structural cues. The proposed framework can be used not only for analysis of biological motion but also to synthesize new motion patterns. A simple motion modeler is presented that can be used to visualize and exaggerate the differences in male and female walking patterns.

Adult↗
PubMed2006

The interaction of eye movements and retinal signals during the perception of 3-D motion direction.

When an object is tracked with the eyes, veridical perception of the motion of that object and other objects requires the brain to take account of and compensate for the eye movement. Here, I explore the effects of version and vergence eye movements on three-dimensional (3-D) motion perception. After demonstrating that eye movement compensation can be poor for detecting small objects moving in depth, I develop two models for how eye movement and visual signals may interact during the perception of 3-D motion direction. The first model assumes that the visual system is aiming to form an explicit representation of 3-D motion. From the results of a second experiment, on 3-D motion direction judgements, I show that this model could only hold with almost perfect 3-D motion compensation, contradicting the results from the first experiment. A second model assumes a much simpler strategy for estimating 3-D motion direction, based on recent experimental work. It predicts that compensation for vergence is not required because the Z-component of 3-D motion is not needed for direction judgements, consistent with the experimental results. This suggests that, for 3-D motion direction discrimination and angle judgements, extraretinal signals from vergence are not used.

Adaptation, Physiological↗
PubMed2006

Vernier acuity is normal in migraine, whereas global form and global motion perception are not.

PURPOSE: A recent study has demonstrated that some people with migraine display impairments of intermediate stages of motion and form processing. Deficits were identified by using tasks that required that local stimulus attributes be integrated into global percepts. Neurons capable of global processing of form and motion are known to be present in extrastriate cortical areas V4 and V5, respectively. It is not clear from the literature whether deficits of global processing in migraineurs are likely to arise from reduced input to extrastriate cortex from primary visual cortex (V1). The purpose of the study was to compare presumed measures of V1 performance (vernier acuity) to measures of global form and motion perception in migraineurs. METHODS: Thirty migraineurs (17 with aura, and 13 without) and 20 age-matched nonheadache control subjects participated. Intermediate level motion and form perceptions were measured using global dot motion stimuli and Glass patterns, respectively. Vernier stimuli were broad vertical bars composed of small dot elements. Both a static luminance stimulus and a motion defined form vernier stimulus were used. RESULTS: Mean migraine and control group performance were not significantly different for either vernier task (static: t(48)=0.39, P=0.70; motion: t(48)=0.29, P=0.77). Mean migraine group performance was significantly worse than in control subjects for both the global form (t(48)=2.06, P=0.04) and global motion (t(48)=2.87, P<0.01) tasks. CONCLUSIONS: On average, migraineurs demonstrate abnormalities of intermediate stages of both motion and form processing. These abnormalities do not appear to arise from dropout of performance at V1, as vernier acuity was normal in the same individuals.

Adolescent↗
PubMed2000

Hindfoot motion after isolated and combined arthrodeses: measurements in anatomic specimens.

Passive motions at the subtalar joint, talonavicular joint and calcaneocuboid joint were measured in eight ankle specimens, using an ultrasonic motion analysis system. Arthrodeses of the three joints were performed in all feasible combinations and the resulting motion change at the unfused joints was determined. Motion at the subtalar joint was not significantly affected by fusion of the calcaneocuboid joint, reduced to one quarter by fusion of the talonavicular and calcaneocuboid joints (double arthrodesis) and almost completely eliminated with all other fusions. Motion at the talonavicular joint was not significantly affected by calcaneocuboid fusion and reduced to approximately one third with the subtalar and the double arthrodesis. Motion at the calcaneocuboid joint was not significantly reduced by subtalar fusion but almost completely eliminated in all fusions involving the talonavicular joint. It is concluded that the talonavicular joint is the key articulation for hindfoot motion. Double arthrodesis preserved significant motion at the subtalar joint. Fusion of the calcaneocuboid joint had no significant influence on remaining hindfoot motion.

Adult↗
PubMed2004

The association between subtalar joint motion and outcome satisfaction in patients with displaced intraarticular calcaneal fractures.

BACKGROUND: There is a paucity of literature on the effect of calcaneal fractures on subtalar joint motion and patient satisfaction. The objective of this study was to determine the relationship between subtalar joint motion and outcome satisfaction in patients who had displaced intraarticular calcaneal fractures. The design of this study was a retrospective analysis from a randomized, controlled clinical trial. The setting was a Level I trauma center. METHODS: Of the 332 displaced intraarticular calcaneal fractures entered into the clinical trial and managed by the senior author, 244 fractures had subtalar joint motion measurements taken at least 12 weeks after fracture, and patient-oriented outcomes were reviewed at 2 years. Nonoperative treatment consisted of ice, elevation, and rest without closed reduction. In the operative group, an extended lateral approach was used with subchondral fixation, plating, and bone grafting when necessary. The Short Form 36 (SF-36), a validated visual analogue scale (VAS), and a gait analogue score measured patient satisfaction. Subtalar joint motion was recorded as percentages of the uninjured limb and grouped into quartiles. RESULTS: The VAS, SF-36 (p <.0001), and the gait satisfaction score (p <.05) all increased significantly with increasing subtalar joint motion. Satisfaction on the VAS and SF-36 was significantly related to subtalar joint motion for men (p <.0001) and in the age groups 30 to 39 (p <.001) and 40 to 49 years (p <0.05). In non-Workman Compensation Board (WCB) clients, higher subtalar joint motion was significantly related to improved satisfaction on VAS and SF-36 (p <.005). Patient satisfaction was significantly related to subtalar joint motion as measured by the VAS when patients reported pre-injury workloads of moderate (p <.05) or heavy (p <.01) regardless of whether they were treated operatively (p <.05) or nonoperatively (p <.0005). CONCLUSIONS: The amount of subtalar joint motion at least 12 weeks after displaced intraarticular calcaneal fracture is significantly related to patient satisfaction at 2 years regardless of the method of treatment.

Adolescent↗
PubMed2005

First metatarsophalangeal joint motion after hallux valgus correction: a cadaver study.

BACKGROUND: Surgical correction of hallux valgus deformities often results in decreased first metatarsophalangeal joint (MTPJ) range of motion. Loss of motion has been shown to affect patient satisfaction. The purpose of this study was to evaluate the immediate change in MTPJ range of motion that occurs after a distal soft-tissue reconstruction (DSTR) and proximal metatarsal osteotomy (PMO). METHODS: DSTR and PMO were done on 16 below-knee cadaver specimens with clinically apparent hallux valgus deformities. Two examiners assessed preoperative and postoperative dorsiflexion (DF), plantarflexion (PF), and the total range of motion of the first MTPJ. The hallux valgus angle (HVA) and 1-2 intermetatarsal angle (1-2 IMA) were measured on simulated weightbearing radiographs before and after operative correction. Changes in motion were analyzed and correlated with the angular measurements. RESULTS: The mean total range of motion preoperatively was 85.4 degrees (DF 70.5 degrees, PF 14.9 degrees) and significantly decreased (p < 0.005) 23.2 degrees to a postoperative value of 62.2 degrees (DF 47.9 degrees, PF 14.3 degrees). There was a significant (p < 0.005) decrease in DF (22.6 degrees) with the operative correction, but the loss of PF (0.6 degrees) was not significant (p = 0.7). There was no correlation between the magnitude of correction (HVA, 1-2 IMA) and the change in PF, DF, or total motion. CONCLUSIONS: Correction of a hallux valgus deformity with a DSTR and PMO is associated with an immediate loss of range of motion that primarily affects the DF arc of the first MTPJ. The selective loss of DF may be related to a nonisometric capsular repair or tight intrinsic musculature, although there was no correlation with the magnitude of angular correction. The immediate decrease in motion observed in this cadaver study underscores the importance of early postoperative joint mobilization to prevent long-term stiffness after bunion surgery.

Aged↗
PubMed2005

Visual motion perception at the time of saccadic eye movements and its relation to spatial mislocalization.

The same retinal image motion can be produced by a variety of combinations of eye and target motion. In natural conditions, extraretinal information disambiguates retinal information for motion perception. By controlling the timing of visual motion with respect to saccades, it was possible to appraise the roles for motion perception of the signal related to saccades occurring in the vicinity of visual motion. When a visual motion was seen before or after a saccade, its perceived direction was biased in the direction opposite to the saccade. The magnitude of the bias depended on the timing of the visual motion with respect to the saccade and the meridian of the visual motion. The bias appears to be independent of the deformation of visual space reported to occur before and after saccades.

Humans↗
PubMed1995

Using motion perimetry to detect visual field defects in patients with idiopathic intracranial hypertension: a comparison with conventional automated perimetry.

Motion perimetry, a method of visual field testing that uses computer graphics to measure motion perception, quantitates a subject's ability to detect a coherent shift in position of dots in a defined circular area against a background of fixed dots. Motion size threshold is defined as the smallest detectable circular target in which dot motion is detected. Subjects respond by touching a computer monitor screen with a light pen, first when they see a target (reaction time) and a second time where motion targets are detected (localization). Reaction time (msec) to the stimulus and localization error (number of pixels from target center) are then calculated and stored. We tested on eye in each of 20 idiopathic intracranial hypertension (IIH) patients and 40 age-matched normal subjects by conventional automated perimetry (Humphrey visual field analyzer, program 24-2) and motion perimetry. Pointwise probability plots of individual abnormal test points for size threshold responses were generated for the IIH patients based on the 95% confidence limits of the normal subject responses. An analysis of the subjects' visual field pairs (motion versus conventional automated perimetry) was performed based on these probability plots. The IIH patients had an elevated mean motion threshold (p < 0.001) and reaction time (p < 0.001) compared with the normal subjects. There were no significant differences for the localization errors. Based on the probability plot analysis, there was good correlation of the visual field defects between the two perimetry tests. In addition, motion perimetry identified nerve fiber bundle-shaped defects in nine patients in whom they were not detected with conventional automated perimetry.

Adult↗
PubMed1999

Is motion processing unitary?

Motion discrimination space is conventionally categorized into motion detection, speed discrimination, and direction discrimination tasks. But an ideal observer uses a unitary motion mechanism that is affected only by the noise level and the difference in speed (or displacement) between two stimuli. We tested whether human performance in the various motion tasks showed the working of a unitary mechanism or the combined outputs of more than one mechanism. We examined the whole motion discrimination space, using random dots that underwent a sudden jump or displacement. The discriminability was measured as a function of the standard and comparison displacements. Both the ideal observer model and a nonideal observer model that contains additive internal noise predict a planar response surface. When the dot motion was noiseless, the planar surface fitted well except for much higher than expected sensitivity for motion detection. This is consistent with a purely temporal mechanism that uses flicker or a purely spatial mechanism that uses the length of time-averaged streaks. It is also consistent with a Weber's law device. When motion noise was added to the displays, the planar response surface again fitted well, although the residuals showed the presence of a speed energy mechanism. We conclude that a unitary motion mechanism exists (nonideal observer model), although its performance may be supplemented by other mechanisms whose main impact is on discrimination of speeds near zero.

Artifacts↗
PubMed2001

Processing of second-order motion stimuli in primate middle temporal area and medial superior temporal area.

Two rhesus monkeys were subjects in a direction-discrimination task involving moving stimuli defined by either first- or second-order motion. Two different second-order motion stimuli were used: drift-balanced motion consisting of a rectangular field of stationary dots and theta motion consisting of the same rectangular field with dots moving in the direction opposite to that of the object. The two types of stimuli involved different segmentation cues between the moving object and the background: temporal structure of the luminance (flicker) in the case of drift-balanced motion and opposed motion in the case of the theta-motion stimulus. Our monkeys were able to correctly report the direction of each stimulus. Single-unit recordings from the middle temporal (MT) and medial superior temporal (MST) areas revealed that 16 out of 38 neurons (41%) from area MT and 34 out of 68 neurons (50%) from area MST responded in a directionally selective manner to the drift-balanced stimulus. The movement of an object defined by theta motion is not explicitly encoded in the neuronal activity in areas MT or MST. Our results do not support the hypothesis that the neuronal activity in these areas codes for the direction of stimulus movement independent of specific stimulus parameters. Furthermore, our results emphasize the relevance of different segmentation cues between figure and background. Therefore the notion that there are multiple sites responsible for the processing of second-order motion is strongly supported.

Animals↗
PubMed1989

Motion processing by chromatic and achromatic visual pathways.

We describe a family of stimuli consisting of colored bars of different orientations, which, when presented in rapid succession, may elicit unambiguous motion perception. These stimuli permitted the isolation of directional spatiotemporal information extracted from oriented luminance clues, from nonoriented chromatic-plus-luminance clues, or, when the stimuli were presented under equiluminant conditions, from pure chromatic clues. As a general rule, matching of orientation induces weaker motion-detection performances than does matching of color. When the orientation clues are in competition with the chromatic ones, motion perception based on the former is always overridden by motion perception based on the latter. We indirectly isolated an oriented chromatic mechanism that also contributes to motion perception. We finally showed that, under equiluminant conditions, matching of orientation across different colors is inefficient in eliciting motion perception, either because motion information is extracted poorly across different chromatic channels or because such channels show little orientational selectivity. Because motion strength determined by each of the manipulated attributes follows different functions with the displacement (or velocity) of the stimuli, we propose the existence of three underlying mechanisms, a luminance mechanism, a chromatic-plus-luminance mechanism, and a pure chromatic mechanism, each of which provides motion information.

Attention↗
PubMed2005

Motion sickness in migraine sufferers.

Motion sickness commonly occurs after exposure to actual motion, such as car or amusement park rides, or virtual motion, such as panoramic movies. Motion sickness symptoms may be disabling, significantly limiting business, travel and leisure activities. Motion sickness occurs in approximately 50% of migraine sufferers. Understanding motion sickness in migraine patients may improve understanding of the physiology of both conditions. Recent literature suggests important relationships between the trigeminal system and vestibular nuclei that may have implications for both motion sickness and migraine. Studies demonstrating an important relationship between serotonin receptors and motion sickness susceptibility in both rodents and humans suggest possible new motion sickness prevention therapies.

Humans↗