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PubMed2003

The use of sequential MR image sets for determining tibiofemoral motion: reliability of coordinate systems and accuracy of motion tracking algorithm.

The use of magnetic resonance imaging has been proposed by many investigators for establishment of joint reference systems and kinematic tracking of musculoskeletal joints. In this study, the intraobserver and interobserver reliability of a strategy to establish anatomic reference systems using manually selected fiducial points were quantified for seven sets of MR images of the human knee joint. The standard error of the measurement of the intraobserver and interobserver errors were less than 2.6 degrees, and 1.2 mm for relative tibiofemoral orientation and displacement, respectively. An automated motion tracking algorithm was also validated with a controlled motion experiment in a cadaveric knee joint. The controlled displacements and rotations prescribed in our motion tracking validation were highly correlated to those predicted (Pearson's correlation = 0.99, RMS errors = 0.39 mm, 0.38 degree). Finally, the system for anatomic reference system definition and motion tracking was demonstrated with a set of MR images of in vivo passive flexion in the human knee.

Adult↗
PubMed2005

Confirmation, refinement, and extension of a study in intrafraction motion interplay with sliding jaw motion.

The interplay between a constant scan speed and intrafraction oscillatory motion produces interesting fluence intensity modulations along the axis of motion that are sensitive to the motion function, as originally shown in a classic paper by Yu et al. [Phys. Med. Biol. 43, 91-104 (1998)]. The fluence intensity profiles are explored in this note for an intuitive understanding, then compared with Yu et al., and finally further explored for the effects of low scan speed and random components of both intrafraction and interfraction motion. At slow scan speeds typical of helical tomotherapy, these fluence intensity modulations are only a few percent. With the addition of only a small amount of cycle-to-cycle randomness in frequency and amplitude, the fluence intensity profiles change dramatically. It is further shown that after a typical 30-fraction treatment, the sensitivities displayed in the single fraction fluence intensity profiles greatly diminish.

Body Burden↗
PubMed2004

Attention to 3-D shape, 3-D motion, and texture in 3-D structure from motion displays.

We used fMRI to directly compare the neural substrates of three-dimensional (3-D) shape and motion processing for realistic textured objects rotating in depth. Subjects made judgments about several different attributes of these objects, including 3-D shape, the 3-D motion, and the scale of surface texture. For all of these tasks, we equated visual input, motor output, and task difficulty, and we controlled for differences in spatial attention. Judgments about 3-D shape from motion involve both parietal and occipito-temporal regions. The processing of 3-D shape is associated with the analysis of 3-D motion in parietal regions and the analysis of surface texture in occipito-temporal regions, which is consistent with the different behavioral roles that are typically attributed to the dorsal and ventral processing streams.

Adult↗
PubMed1993

Quantification of monocular optokinetic nystagmus asymmetries and motion perception with motion-nulling techniques.

When tested monocularly, strabismic and amblyopic subjects often show asymmetries of optokinetic nystagmus (OKN), with OKN being more readily elicited by temporal-to-nasal than by nasal-to-temporal stimulus motion. We tested five visually normal subjects and ten strabismic and/or amblyopic subjects by use of motion-nulling stimuli, which consisted of superimposed temporal-to-nasal and nasal-to-temporal sinusoidal-grating components with a summed contrast of 100%. Both the direction of OKN and the subject's perceived direction of motion (PDM) were tested. Most normal subjects showed symmetrical OKN and PDM, but a rightward OKN bias was observed in one of the visually normal subjects. Temporal-to-nasal eye-movement biases were seen in most strabismic and amblyopic subjects, whereas PDM biases were smaller and less frequent. The primary purpose of this study was to demonstrate the feasibility of quantifying OKN and PDM asymmetries in a diverse group of visually abnormal adults by use of the motion-nulling technique. Application of this technique to larger and more homogeneous clinical populations may contribute to the continued differentiation and characterization of variants of the visual disorders associated with strabismus and amblyopia and with other defects of binocular vision.

Adolescent↗
PubMed2004

[Active range of cervical motion in healthy subjects and in spinal disorders. DBC equipment validity in complex cervical motion evaluation].

UNLABELLED: Active Range of motion (AROM) is one of the crucial parameters assessed in the cervical spine evaluation. Repeated standardized AROM evaluation enables objectified monitoring of disease progress or therapy related improvement. Active spine therapy according to DBC (Documentation Based Care) requirement is a contemporary therapeutic system with proven efficacy in spinal disorders. The therapeutic concept f DBC is mechanotherapy based and introduces special devices designed for active exercises in strictly defined range, rate and load. DBC-3CR device is constructed for active motion (composed of rotation, anteflexion and lateral flexion) exercise of the cervical spine with repeated dynamic load. Technical properties allow to avail the machine for diagnostic purposes as far complex range of motion is concerned. PURPOSE: Comparison of AROM between healthy volunteers and patients with cervical disorders. Evaluation of DBC-3CR validity in complex AROM measurement Patients: A--99 healthy volunteers; B--106 patients with chronic neck pain resulting from cervical spondylosis; C--36 patients with acute neck pain related to cervical disc disease or whiplash injury. METHODS: Complex AROM detection with DBC-3CR was compared with reference measurements (goniometric and inclinometric simple AROM detection). Age and sex dependence of AROM among healthy subjects was observed. AROM was compared between B, C and reference groups. DISCUSSION: AROM was significantly decreased in patients with chronic and acute neck pain. Motion limitation pattern was symmetric in both groups. The presence of linear dependency between complex AROM acquired with DBC-3CE and rotation acquired with goniometer was observed (Pearson coefficient 0.81 at p < 0.0001). CONCLUSIONS: I. DBC-3CR device is useful in AROM evaluation. 2. AROM in healthy subjects decreases with age, but is sex--independent parameter. 3. In cervical spondylosis AROM is symmetrically reduced as far as rotation and lateral flexion are concerned. 4. Acute cervical pain results in symmetric AROM limitation.

Adult↗
PubMed1987

Head movements in low and high gravitoinertial force environments elicit motion sickness: implications for space motion sickness.

Astronauts report that head movements in flight tend to bring on symptoms of space motion sickness (SMS). We evaluated how head movements in pitch, yaw, and roll--made both with normal vision and eyes-occluded--affect susceptibility to motion sickness in the zero G phase of parabolic flight maneuvers. The findings are clearcut: pitch head movements are most provocative, yaw least provocative, and roll intermediate. Susceptibility is greater with normal vision than with eyes occluded. The same susceptibility pattern emerged for head movements in the 1.8-2.0 G phase of parabolic flight. These experiments suggest that SMS is not a unique nosological entity but, rather, is the consequence of exposure to nonterrestrial force levels. Head movements during departures in either direction from 1 G elicit symptoms. This implies that, rather than speaking of "space motion sickness," it would be more appropriate to think in terms of "nonterrestrial motion sickness."

Gravitation↗
PubMed1987

Effects of proposed preflight adaptation training on eye movements, self-motion perception, and motion sickness: a progress report.

A program has been initiated to develop apparatus and procedures to preadapt astronauts to the sensory rearrangement associated with weightlessness in spaceflight. If space motion sickness is a consequence of adaptation to that sensory rearrangement, preflight training could afford astronauts significant relief from the motion sickness. The preflight adaptation trainer (PAT) was designed to produce rearranged relationships between visual and otolith signals analogous to those experienced in space. Investigations have been undertaken with three prototype trainers. The results indicated that exposure to the PAT sensory rearrangement altered self-motion perception, induced motion sickness, and changed the amplitude and phase of the horizontal eye movements evoked by roll stimulation. However, the changes were inconsistent. Appropriate measures of adaptation and protocols for producing the adaptation efficiently remain to be determined.

Adaptation, Physiological↗
PubMed1986

Head movements in non-terrestrial force environments elicit motion sickness: implications for the etiology of space motion sickness.

Space motion sickness has become an operational concern in manned space flight. Considerable evidence exists that head movements in free fall, especially pitch movements, are provocative until adaptation occurs (3,4,8,9,11,17,18,22,26). The question arises whether space motion sickness is an unique nosological entity or is due to body movements in a nonterrestrial force environment, a force environment for which the body's dynamic sensory-motor adaptions to 1 G are no longer appropriate (14,16,18-21). To evaluate this issue, we had subjects make controlled head movements during exposure to high gravitoinertial force levels, 1.8-2.0 G, in parabolic flight maneuvers. Head movements in pitch with eyes open were most evocative of motion sickness, yaw movements with eyes covered were least provocative. This pattern is identical to that which occurs when the same types of head movements are made in the free fall phase of parabolic maneuvers (17,18). It appears that space motion sickness is the consequence of prolonged exposure to a non-terrestrial force background rather than of exposure to free fall per se.

Adult↗
PubMed1994

Inter- and intraexaminer reliability of a single, digital inclinometric range of motion measurement technique in the assessment of lumbar range of motion.

OBJECTIVE: The between and within examiner reliability of a range of motion digital inclinometer was evaluated for lumbar flexion, extension and right and left lateral flexion. DESIGN: Blinded, lumbar range of motion instrumentation reliability. SETTING: Private college research and ambulatory patient care facility. PARTICIPANTS: Twenty-eight asymptomatic persons recruited from a private college. This included students, staff and faculty that ranged from 23-36 yr, with no history of back pain or surgery or back injury 6 wk prior to entry into the study. INTERVENTION: Lumbar range of motion examination, twice by each examiner, or four times in all per subject. MAIN OUTCOME MEASURE: Lumbar range of motion, measured in degrees. RESULTS: Intraclass correlation (ICC) revealed lack of reliability for this device except flexion, but intrinsic limitations of the instrument suggests that flexion as well may not be reliable. The p value of .05 was used for statistical significance and Burdock's recommended value of .75 represented the minimum R value for reliability. CONCLUSION: Most of the reliability values did not meet Burdock's recommended minimum R value, and the R values for flexion may have met minimum criteria due to intrinsic limitations of the instrument itself. Due to the findings of this study, we conclude that the Orthoranger II digital inclinometer is not reliable, between and/or within examiners, for measuring lumbar flexion, extension or lateral flexion. Because there was evidence to suggest other variables which were not accounted for, and which could have affected final results, the development of a streamlined protocol may result in more consistent findings. Further research is needed to either support or dispute these results before this instrument can be recommended as an assessment tool in clinical practice or in clinical trials.

Adult↗
PubMed1977

Optokinetic motion sickness: continuous head movements attenuate the visual induction of apparent self-rotation and symptoms of motion sickness.

Symptoms of motion sickness are sometimes experienced during exposure to optokinetic stimulation. Two experimetns were performed to compare the symptoms of motion sickness elicited when subjects were exposed to incremental changes in optokinetic stimulation while sitting passively and while continuously executing shoulder-to-shoulder head movements. In the first experiment, a fixed head-movement frequency (20 cpm) was used, wheras in the second the subjects varied the frequency of their head movements in order to maintain suppression of illusory self-rotation. In both experiments, subjects in the head-moving condition had fewer and less severe symptoms of motion sickness and experienced illusory self-rotation after longer exposure times and at higher optokinetic velocities than in the head-stationary condition. Subjects in th- head-movement condition of the second experiment increased the frequency of their head movements as the velocity of optokinetic stimulation increased. The symptoms of motion sickness elicited during optokinetic stimulation tended to be dizziness, headache, eye-strain, and stomach awareness appearing in no fixed order. The pattern and constellation of symptoms are unlike those elicited by vestibular stimulation.

Eye Movements↗
PubMed1996

Visual motion-detection circuits in flies: small-field retinotopic elements responding to motion are evolutionarily conserved across taxa.

The Hassenstein-Reichardt autocorrelation model for motion computation was derived originally from studies of optomotor turning reactions of beetles and further refined from studies of houseflies. Its applicaton for explaining a variety of optokinetic behaviors in other insects assumes that neural correlates to the model are principally similar across taxa. This account examines whether this assumption is warranted. The results demonstrate that an evolutionarily conserved subset of neurons corresponds to small retinotopic neurons implicated in motion-detecting circuits that link the retina to motion-sensitive neuropils of the lobula plate. The occurrence of these neurons in basal groups suggests that they must have evolved at least 240 million years before the present time. Functional contiguity among the neurons is suggested by their having layer relationships that are independent of taxon-specific neurons, or the absence of orientation-specific motion-sensitive levels in the lobula plate.

Animals↗
PubMed1982

The multicentric character of normal left ventricular wall motion. Implications for the evaluation of regional wall motion abnormalities by contrast angiography.

Current radiologic approaches to evaluation of regional ventricular wall motion generally employ rectilinear hemichords ("hemiaxes") or radial hemichords ("chords"), defined by the presumptions that wall segments move either perpendicularly toward the ventricular long axis, or toward some common center, respectively. In order to test these presumptions, the end-systolic and end-diastolic frames of 17 normal right anterior oblique (left) ventriculograms were analyzed, using a digitizer and a computer. The motion vectors of 47 points on each ventriculographic perimeter were defined by centers (located along the ventricular long axis). Twenty average centers were found which could be represented by three centers, for six regions of the normal angiographic silhouette. Computer models of abnormal regional wall motion, using three centers, disclosed appreciable discrepancies among the chord, hemiaxis and rectilinear area methods, particularly for the apical and basal wall regions. The model data suggest that the wall region, itself, dictates the center which should be used for measuring an abnormality of regional wall motion.

Cardiac Catheterization↗
PubMed2006

Global motion mechanisms compensate local motion deficits in a patient with a bilateral occipital lobe lesion.

Successive stages of cortical processing encode increasingly more complex types of information. In the visual motion system this increasing complexity, complemented by an increase in spatial summation, has proven effective in characterizing the mechanisms mediating visual perception. Here we report psychophysical results from a motion-impaired stroke patient, WB, whose pattern of deficits over time reveals a systematic shift in spatial scale for processing speed. We show that following loss in sensitivity to low-level motion direction WB's representation of speed shifts to larger spatial scales, consistent with recruitment of intact high-level mechanisms. With the recovery of low-level motion processing WB's representation of speed shifts back to small spatial scales. These results support the recruitment of high-level visual mechanisms in cases where lower-level function is impaired and suggest that, as an experimental paradigm, spatial summation may provide an important avenue for investigating functional recovery in patients following damage to visually responsive cortex.

Aged↗
PubMed2000

A model of motion adaptation and motion after-effects based upon principal component regression.

A computational model to help explain effects of adaptation to moving signals is compared with established energy (linear regression) models of motion detection. The proposed model assumes that processed image signals are subject to error in both dimensions of space and time. This assumption constrains models of motion perception to be based upon principal component regression rather than linear regression. It is shown that response suppression of model complex cell neurons that input into the model may account for (1) increases in perceived speed after adaptation to static patterns and testing with slowly moving patterns, (2) significant increases in perceived speed after adaptation to patterns moving at a medium speed and testing at high speed, and (3) decreases in perceived speed in the opponent direction to a quickly moving adapting signal. Neither of predictions (2) or (3) are general features of established accounts of motion detection by visual processes based upon linear regression. Comparisons of the proposed model's speed transfer function with existing psychophysical data suggests that the visual system processes motion signals with the tacit assumption that image measurements are subject to error in both space and time.

Animals↗
PubMed1991

Time-motion reconstruction of mitral leaflet motion from two-dimensional echocardiography in mitral valve prolapse.

To assess the contributions of mitral leaflet billowing and exaggerated systolic mitral anular expansion to posterior motion of mitral leaflets recognized as mitral valve prolapse (MVP) by M-mode echocardiography, time-motion reconstructions of the anteroposterior displacement of points equally spaced along the anterior and posterior mitral leaflets were derived by computer-assisted analysis of 2-dimensional echocardiograms. Late or holosystolic posterior displacement of mitral leaflets, greater than or equal to 2 mm, occurred in the reconstructions from 24 of 24 (100%) patients with MVP with leaflet billowing and in 20 of 24 (83%) patients with MVP without leaflet billowing compared with 4 of 35 (11%) age-sex matched normal adults (both p less than 0.0000002). Posterior motion of the posterior mitral leaflet in time-motion reconstruction was significantly less with respect to the posterior end of the mitral anulus than with respect to the chest wall in patients with nonbillowing MVP (1.6 +/- 1.9 vs 2.7 +/- 1.6, p less than 0.02), but not in those with leaflet billowing (3.6 +/- 1.8 vs 3.9 +/- 1.8, p = not significant), because anular expansion contributed importantly to MVP in the former but not in the latter group. Thus, M-mode echocardiographic patterns of MVP reflect the separate but interacting effects of distinct abnormalities of mitral anular and leaflet dynamics.

Adolescent↗
PubMed1994

The visual perception of three-dimensional shape from self-motion and object-motion.

To evaluate the influence of egomotion on the three-dimensional visual processing of structure-from-motion (SFM), we compared the visual discrimination between planar and spherical surfaces during subject-translation, object-translation, or rotation of the object in depth. Performance was the best for object-rotation, intermediate for subject-translation, and the poorest for object-translation--and thus increased with the quality of retinal image stabilization achieved in the different conditions. This suggests that the major role of self-motion information was to stabilize retinal images. In view of previous results, we propose that the interactions between self-motion information and SFM are reduced to functional complementarity, in the sense that self-motion can lift visual ambiguities but does not improve the sensitivity of SFM processes.

Adult↗
PubMed1990

Segmental motion of the proximal carpal row: their global effect on the wrist motion.

The contribution of the scapho-lunate and luno-triquetral joints to global wrist motion was studied in 11 fresh-frozen cadaver specimens. The carpus were labeled with metallic markers and the joints were selectively transfixed with wires. The wrist was allowed to follow its natural radial and ulnar deviation during flexion and extension, extension and flexion during radial and ulnar deviation, respectively. The data was collected by means of radiography, goniometric measurement, and computer analysis. The proximal carpal row (the intercalated segment) although anatomically represented as a row, presented through its two intersegmental joints, a definite segmental behavior. Each intersegmental joint of the proximal carpal row influenced global wrist motion in all directions but to a different degree for each plane of motion. The segmental joints within the intercalated segment collectively govern 40% of the wrist flexion, 33% of extension, and 10% of ulnar deviation. The scaphoid through its scapho-lunate link exerts a governing effect on total intersegmental proximal carpal row contribution to the global wrist motion.

Adult↗
PubMed2006

Three-dimensional quantification of cardiac surface motion: a newly developed three-dimensional digital motion-capture and reconstruction system for beating heart surgery.

OBJECTIVE: This study aimed to evaluate our newly developed 3-dimensional digital motion-capture and reconstruction system in an animal experiment setting and to characterize quantitatively the three regional cardiac surface motions, in the left anterior descending artery, right coronary artery, and left circumflex artery, before and after stabilization using a stabilizer. METHODS: Six pigs underwent a full sternotomy. Three tiny metallic markers (diameter 2 mm) coated with a reflective material were attached on three regional cardiac surfaces (left anterior descending, right coronary, and left circumflex coronary artery regions). These markers were captured by two high-speed digital video cameras (955 frames per second) as 2-dimensional coordinates and reconstructed to 3-dimensional data points (about 480 xyz-position data per second) by a newly developed computer program. RESULTS: The remaining motion after stabilization ranged from 0.4 to 1.01 mm at the left anterior descending, 0.91 to 1.52 mm at the right coronary artery, and 0.53 to 1.14 mm at the left circumflex regions. Significant differences before and after stabilization were evaluated in maximum moving velocity (left anterior descending 456.7 +/- 178.7 vs 306.5 +/- 207.4 mm/s; right coronary artery 574.9 +/- 161.7 vs 446.9 +/- 170.7 mm/s; left circumflex 578.7 +/- 226.7 vs 398.9 +/- 192.6 mm/s; P < .0001) and maximum acceleration (left anterior descending 238.8 +/- 137.4 vs 169.4 +/- 132.7 m/s2; right coronary artery 315.0 +/- 123.9 vs 242.9 +/- 120.6 m/s2; left circumflex 307.9 +/- 151.0 vs 217.2 +/- 132.3 m/s2; P < .0001). CONCLUSIONS: This system is useful for a precise quantification of the heart surface movement. This helps us better understand the complexity of the heart, its motion, and the need for developing a better stabilizer for beating heart surgery.

Animals↗