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PubMed2000

Autogenic-feedback training exercise is superior to promethazine for control of motion sickness symptoms.

Motion sickness symptoms affect approximately 50% of the crew during space travel and are commonly treated with intramuscular injections of promethazine. The purpose of this paper is to compare the effectiveness of three treatments for motion sickness: intramuscular injections (i.m.) of promethazine, a physiological training method (autogenic-feedback training exercise [AFTE]), and a no-treatment control. An earlier study tested the effects of promethazine on cognitive and psychomotor performance and motion sickness tolerance in a rotating chair. For the present paper, motion sickness tolerance, symptom reports, and physiological responses of these subjects were compared to matched subjects selected from an existing database who received either AFTE or no treatment. Three groups of 11 men, between the ages of 33 and 40 years, were matched on the number of rotations tolerated during their initial rotating-chair motion sickness test. The motion sickness test procedures and the 7-day interval between tests were the same for all subjects. The drug group was tested under four treatment conditions: baseline (no injections), a 25 mg dose of promethazine, a 50 mg dose of promethazine, and a placebo of sterile saline. AFTE subjects were given four 30-minute AFTE sessions before their second, third, and fourth motion sickness tests (6 hours total). The no-treatment control subjects were only given the four rotating-chair tests. Motion sickness tolerance was significantly increased after 4 hours of AFTE when compared to either 25 mg (p < 0.00003) or 50 mg (p < 0.00001) of promethazine. The control and promethazine groups did not differ. AFTE subjects reported fewer or no symptoms at higher rotational velocities than subjects in the control or promethazine groups. The primary physiological effect of promethazine was an inhibition of skin conductance level. The AFTE group showed significantly less heart rate and skin conductance variability during motion sickness tests administered after training.

Adult↗
PubMed2001

The effects of age and sex on susceptibility to motion sickness.

BACKGROUND: The present investigation is concerned with the role of sex, age and experience in determining motion sickness susceptibility. HYPOTHESIS: Motion sickness susceptibility varies with sex and age, and may be related to the level of physical activity sustained by the individual. METHODS: Three surveys were conducted. The first included school age children (9-18 yr) and addressed motion experience and motion sickness on 13 forms of transport. The second questionnaire sought to determine whether these sex differences could be understood in terms of differential involvement in various forms of physical activity. The third survey addressed the role of age and sex effects in a college age population. RESULTS: The first study revealed significantly greater motion sickness for female as compared with male subjects on devices with which both groups were equivalent in terms of exposure history. The second study showed little relation between an individual's level of physical activity and susceptibility to motion sickness. The results of the third study were in essential agreement with the first survey and revealed no significant interactions between age and sex, suggesting that sex differences remain stable across this age range. CONCLUSION: Our conclusions regarding these surveys are that sex differences in motion sickness do not vary significantly with age and cannot be accounted for by differences in exposure to motion or physical activity. There was also little evidence for the notion that men are more reticent to report motion sickness.

Adolescent↗
PubMed2001

A motion sickness maximum around the 0.2 Hz frequency range of horizontal translational oscillation.

BACKGROUND: Low frequency translational oscillation can provoke motion sickness in land vehicles, ships and aircraft. Although controlled motion experiments indicate a progressive increase in nauseogenicity as frequency decreases toward 0.2 Hz, few data are available on the existence of a definite maximum nauseogenic potential of motion around 0.2 Hz, or decreased nauseogenicity below this frequency. HYPOTHESIS: Nauseogenicity should be maximal around 0.2 Hz. METHODS: We selected 12 subjects for high motion sickness susceptibility, and they were exposed to horizontal sinusoidal motion (1.0 m.s(-2) peak acceleration) at 3 different frequencies (0.1, 0.2 and 0.4 Hz), at 1-wk intervals at the same time of day, according to a factorial design. Subjects were seated comfortably in the upright position with head erect. Fore-aft motion was through the body and head X-axis. Motion was stopped (motion endpoint) at moderate nausea or after 30 min. RESULTS: The proportion of subjects experiencing moderate nausea was maximal at the intermediate frequency: 8/12 at 0.1 Hz, 12/12 at 0.2 Hz, 7/12 at 0.4 Hz. The mean time to motion endpoint was significantly (p < 0.01) shorter at the intermediate frequency: 18.0 min at 0.1 Hz; 11.2 min at 0.2 Hz; 20.2 min at 0.4 Hz. Similar frequency patterns emerged for other sickness ratings. The equivalent times to achieve moderate nausea using estimated values to correct for subjects who reached the 30 min time cut-off were: 22.7 min at 0.1 Hz; 11.2 min at 0.2 Hz; 28.1 min at 0.4 Hz. CONCLUSIONS: A maximum nauseogenic potential around 0.2 Hz was substantiated.

Acceleration↗
PubMed2002

Effect of magnitude and direction of horizontal oscillation on motion sickness.

BACKGROUND: Various types of motion and visual scene can cause motion sickness, but sickness in land transport seems to be often associated with variations in horizontal acceleration. If horizontal oscillation causes sickness, it seems reasonable to assume that greater amounts of motion (i.e., an increased magnitude of motion or an increased duration of motion) will increase the extent of the sickness. HYPOTHESIS: It was hypothesized that the magnitude, direction, and duration of horizontal oscillation would affect the sickness experienced by subjects. METHOD: The 144 subjects were exposed to horizontal sinusoidal oscillation at a frequency of 0.315 Hz while seated in a closed cabin with their eyes open for up to 30 min. Subjects were exposed to one of 12 conditions with either fore-and-aft or lateral oscillation at magnitudes of either: (i) 0.28 ms(-2) rms, (ii) 0.56 ms(-2) rms, (iii) 0.70 ms(-2) rms, (iv) 0.89 ms(-2) rms, (v) 1.11 ms(-2) rms, or (vi) a stationary control condition. Subjects provided ratings of their motion sickness symptoms at 1-min intervals during the 30-min exposures. RESULTS: At a frequency of 0.315 Hz, an increase in either the magnitude or the duration of horizontal oscillation resulted in increases in the incidence of motion sickness. There were significant positive correlations between self-ratings of motion sickness susceptibility provided by subjects before participating in the experiment and their illness ratings during the experiment. CONCLUSIONS: At a frequency of 0.315 Hz, motion sickness caused by horizontal oscillation increases with increases in the magnitude and duration of horizontal oscillation. For the conditions of this study, the sickness was similar with fore-and-aft and lateral oscillation.

Acceleration↗
PubMed2003

Input organization of multifunctional motion-sensitive neurons in the blowfly.

Flies rely heavily on visual motion cues for course control. This is mediated by a small set of motion-sensitive neurons called lobula plate tangential cells. A single class of these, the centrifugal horizontal (CH) neurons, play an important role in two pathways: figure-ground discrimination and flow-field selectivity. As was recently found, the dendrites of CH cells are electrically coupled with the dendritic tree of another class of neurons sensitive to horizontal image motion, the horizontal system (HS) cells. However, whether motion information arrives independently at both of these cells or is passed from one to the other is not known. Here, we examine the ipsilateral input circuitry to HS and CH neurons by selective laser ablation of individual interneurons. We find that the response of CH neurons to motion presented in front of the ipsilateral eye is entirely abolished after ablation of HS cells. In contrast, the motion response of HS cells persists after the ablation of CH cells. We conclude that HS cells receive direct motion input from local motion elements, whereas CH cells do not; their motion response is driven by HS cells. This connection scheme is discussed with reference to how the dendritic networks involved in figure-ground detection and flow-field selectivity might operate.

Animals↗
PubMed2004

Incidence and characterization of patient motion in myocardial perfusion SPECT: Part 1.

UNLABELLED: Despite advances in (99m)Tc-based radiopharmaceuticals and multiple-detector gantries, patient motion in myocardial perfusion SPECT acquisitions is still problematic and may produce artifacts that mimic coronary artery disease. METHODS: A prospective cross-sectional study of 800 myocardial perfusion SPECT studies performed with (99m)Tc-based radiopharmaceuticals at 3 private nuclear medicine sites was used to determine the incidence, type, and location of visually detectable motion. The rotating cinematic display and sinograms of the ungated datasets were visually assessed by 2 experienced technologists unaware of the other observer's responses and the clinical outcome. RESULTS: Among the 800 studies analyzed, 36% contained visually detectable motion. Motion was seen on 31.5% of rest studies, compared with 40.5% of stress studies (P = 0.004). The most common type of motion detected was multiple bounce, which represented 47.6% of motion. Left anterior oblique and anterior were the most common specific locations in which patient motion was detected in the raw data. CONCLUSION: This investigation established the significant incidence of patient motion during (99m)Tc-based myocardial perfusion SPECT studies that, fully realized, has the potential to introduce artifacts leading to false-positive findings. Further investigation of the impact of various types and degrees of patient motion is recommended.

Adolescent↗
PubMed2006

Motion sickness: advances in pathogenesis, prediction, prevention, and treatment.

Motion sickness has a major influence on modern traveling activities and the rapidly spreading engagement in virtual reality immersion. Recent evidence emphasizes the role of the otoliths in the pathogenesis of motion sickness, and several new theories may help explain its occurrence beyond the traditional sensory conflict theory. A promising new direction is the recently reported association of genetic polymorphism of the alpha2-adrenergic receptor with increased autonomic response to stress and motion sickness. Various physiological measures for the evaluation and prediction of motion sickness have been tested. However, no single parameter has yet been found to be of high enough sensitivity and specificity for the diagnosis or prediction of individual motion sickness susceptibility. A number of pharmacological and non-pharmacological countermeasures are used for the prevention and treatment of motion sickness. The non-pharmacological options include all procedures that reduce conflicting sensory input, accelerate the process of multi-sensory adaptation, and promote psychological factors which enable the subject to cope with his/her condition. The most effective anti-motion sickness drugs are central acting anticholinergics and H1 antihistamines; however, adverse effects on psychomotor performance may limit their use in drivers, pilots, and naval crewmembers. Recent studies may be relevant to our understanding of the link between motion sickness, migraine, vertigo, and anxiety. Based on these findings and on recent neurochemical data, the development of new anti-motion sickness agents is a promising field of investigation.

Adaptation, Physiological↗
PubMed1989

Cord/spine motion in experimental spinal cord injury.

We examined cord motion and cord-spine coupling associated with the axial tension and dorsal impact models of spinal cord injury. In 20 cats, distraction forces up to 15 kg were applied. Five microliters of radiopaque agent was injected into the central cord at C4-C7 (14 cats) and T6-L1 (6 cats) at 2-mm intervals. In 20 cats, 300 g/cm impacts were delivered after injection of contrast at 2-mm intervals from the impact point. Trials were conducted under fluoroscopy. At 5-kg distraction, vertebral motion averaged 2.12 mm and cord motion averaged 1.03 mm (coupling ratio = .49). At 10-kg coupling increased to .75. Between 10 and 15-kg distraction, the amount of increase in cord length slowed, as did the ratio (.59). Differences in length between load groups were significant at most levels, and motion corresponded with histologic injury reported previously. In the thoracolumbar region, minimal spine motion and no cord motion occurred. Spine motion was not seen with dorsal impact although cord motion at 2 mm from impact averaged 1.3 mm/300 g/cm, which decreased away from the impact point. The spinal cord has limited elasticity, which may be related to injury. Because spine and cord motion occur in clinical injury, experimental models need to incorporate this element.

Animals↗
PubMed1989

The "motion-blind" patient: low-level spatial and temporal filters.

The "motion-blind" patient previously described by Zihl et al. (1983) was investigated using standard psychophysical procedures with stimuli whose spatial and temporal properties could be separately manipulated. Detection experiments for sinewave grating stimuli of varying spatial and temporal frequency showed sensitivity in this patient to be only slightly impaired. Temporal integration for stimuli of varying spatiotemporal frequency exhibited the expected space-time covariation seen in normal vision. An examination of the suprathreshold discriminative capacity of this patient was undertaken for spatial frequency, contrast, and temporal frequency. Although all of these discriminative functions were impaired, those concerning temporal frequency or velocity were dramatically reduced. No similar loss was seen for spatial frequency discrimination for moving or temporally varying stimuli. No measurable temporal frequency discrimination was present above 6 Hz and no velocity discrimination above 6 degrees/sec. Experiments involving the direction discrimination of suprathreshold drifting gratings of arrays of random dots revealed an inability to perceive direction of movement above a velocity of about 6 degrees/sec. Contrast thresholds contingent on direction of motion of a drifting grating also showed a much greater deficit than simple detection. Apparent motion using 2-flash random dot kinematograms revealed that the residual motion vision of this patient corresponded to the "short-range" motion process of normal vision. This process originally defined by Braddick (1974) operates over restricted space and time intervals. Apparent motion could only be supported by a narrow range of intermediate spatial displacements. These results suggest that this patient does exhibit some residual motion perception, probably corresponding to a severely impaired "short-range" mechanism. The patient's relatively intact ability to perform simple types of discrimination but severe impairment of performance at making judgments relevant to the nature of motion of the same stimuli suggests that while the components necessary for the analysis of motion are intact their more global associations have been disrupted. This implicates an extrastriate locus of the brain damage. Alternative explanations for the nature of the deficit are discussed.

Biomechanical Phenomena↗
PubMed1996

Visual motion-detection circuits in flies: parallel direction- and non-direction-sensitive pathways between the medulla and lobula plate.

The neural circuitry of motion processing in insects, as in primates, involves the segregation of different types of visual information into parallel retinotopic pathways that subsequently are reunited at higher levels. In insects, achromatic, motion-sensitive pathways to the lobula plate are separated from color-processing pathways to the lobula. Further parallel subdivisions of the retinotopic pathways to the lobula plate have been suggested from anatomical observations. Here, we provide direct physiological evidence that the two most prominent of these latter pathways are, indeed, functionally distinct: recordings from the retinotopic pathway defined by small-field bushy T-cells (T4) demonstrate only weak directional selectivity to motion, in striking contrast with previously demonstrated strong directional selectivity in the second, T5-cell, pathway. Additional intracellular recordings and anatomical descriptions have been obtained from other identified neurons that may be crucial in early motion detection and processing: a deep medulla amacrine cell that seems well suited to provide the lateral interactions among retinotopic elements required for motion detection; a unique class of Y-cells that provide small-field, directionally selective feedback from the lobula plate to the medulla; and a new heterolateral lobula plate tangential cell that collates directional, motion-sensitive inputs. These results add important new elements to the set of identified neurons that process motion information. The results suggest specific hypotheses regarding the neuronal substrates for motion-processing circuitry and corroborate behavioral studies in bees that predict distinct pathways for directional and nondirectional motion.

Animals↗
PubMed1996

Visibility of motion in infant vernier displays, using adult subjects.

Motion is frequently incorporated in stimuli used for psychophysical testing of vernier acuity in infants and young children. In such stimuli, detection of the vernier offset is necessary in order to perceive the motion. Research described in this report tested whether the perception of a vernier offset is sufficient to signal the stimulus motion in adults. We measured how motion detectability changed as a function of vernier offset for two adult subjects, using a stimulus similar to that employed by other authors to measure vernier acuity in infants and children. Motion visibility varied with offset size, achieving a detectability of motion (d') of 0.95 (comparable to two-alternative forced-choice thresholds) at stimulus offsets of 16-19 s arc. In comparison to the motion, the stimulus offset itself was much easier to see, being detectable on 95-100% of trials with the smallest offset, 6.6 s arc. This distinction, between the visibility of motion and the visibility of the vernier offset itself, should be considered when interpreting vernier results using such displays, especially in infants and children for whom motion may be the attractive cue.

Adult↗
PubMed1991

Chromatin motion in neuronal interphase nuclei: changes induced by disruption of intermediate filaments.

Motion of nucleoli within interphase nuclei, known as nuclear rotation, may be used as a measure of motion of chromatin domains within the global confines of the nucleus. Mechanisms by which chromatin domains are transposed remain enigmatic. It has been established that nuclei are anchored by a network of intermediate filaments, structural proteins which share epitopes with nuclear lamins and possibly representing a constraint on nuclear rotation. It is postulated that selective removal of this constraint, by acrylamide, would result in increased chromatin motion. Mean rates of nucleolar displacement were quantified in neurons, in vitro. Nuclear rotation increased from a mean control rate of 0.102 +/- 0.002 micron/min (n = 52) to a maximum mean rate of 0.207 +/- 0.026 micron/min (n = 11), after 23 hr of exposure to 4 mM acrylamide. Despite this significant increase in motion of intranuclear domains, cytoplasmic structures in the immediate juxtanuclear area did not exhibit increases in rates of motion. Immunocytochemistry was used to visualize cytoskeletal structures and to assay selective disruption of neurofilaments by acrylamide. Increased rates of chromatin motion coincided with breakdown of the intermediate filament network. Ultrastructural analyses showed that the increase in chromatin motion induced by acrylamide was also associated with a significant (P less than 0.005) change in the thickness of the nuclear lamina, decreasing from 20.9 +/- 5.10 nm (n = 159) in controls to 18.9 +/- 3.1 nm (n = 148), to 19.5 +/- 3.6 nm (n = 240) and to 16.1 +/- 4.4 nm (n = 103) at 4, 8 and 22 hr exposure, respectively. Moreover, the number of mitochondria per unit area changed significantly (P less than 0.0001) with exposure to acrylamide, increasing from 9.1 +/- 2.2 mitochondrial profiles in controls to 16.5 +/- 5.3 profiles after 22 hr exposure to acrylamide. Distribution of other cytoskeletal components, actin and microtubules, was not altered and does not appear to play a significant role in the observed increase in rates of nuclear rotation. We conclude that the removal of the damping effects on chromatin motion normally imposed by the nuclear lamina and by intermediate filaments results in increased chromatin motion.

Acrylamide↗
PubMed2001

PROPELLER MRI: clinical testing of a novel technique for quantification and compensation of head motion.

While head motion is considered a significant problem in magnetic resonance imaging (MRI), there is no data to quantify its extent, severity, or effect on image quality. PROPELLER (Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction) MRI offers a novel means of quantifying and compensating for head motion. We performed axial T2-weighted PROPELLER (motion corrected: P-CR; uncorrected: P-UNCR) and conventional MRI (CONV), with equal scan times, in five normal volunteers and 35 clinical subjects. Volunteers were examined lying still and performing two separate head movements (shake "no" and nod "yes") to assess detection and compensation of in-plane motion by PROPELLER MRI. Images were examined by three radiologists for motion artifact and for overall image quality. Head rotation and translation was detected in all subjects during each slice acquisition, with expected changes occurring with volunteer head motion. Motion artifact was less commonly seen on PROPELLER than CONV MR (chi(2) test P < 0.001). PROPELLER was preferred over CONV in all subjects (P < 0.05) and P-CR was judged superior to P-UNCR (P = 0.02). Intracranial pathology was equally or better demonstrated with PROPELLER. PROPELLER MRI offers a means of quantifying head motion, reducing motion artifact, and improving image quality.

Brain↗
PubMed2006

Analysis of residual coronary artery motion for breath hold and navigator approaches using real-time coronary MRI.

Coronary artery MRI methods utilize breath holds, or diaphragmatic navigators, to compensate for respiratory motion. To increase image quality and navigator (NAV) gating efficiency, slice tracking is used, with more sophisticated affine motion models recently introduced. This study assesses the extent of remaining coronary artery motion in free breathing NAV and single and multi breath hold coronary artery MRI. Additionally, the effect of the NAV gating window size was examined. To visualize and measure the respiratory induced motion, an image containing a coronary artery cross section was acquired at each heartbeat. The amount of residual coronary artery displacement was used as a direct measure for the performance of the respiratory motion correction method. Free breathing studies with motion compensation (slice tracking with 5 mm gating window) had a similar amount of residual motion (0.76+/-0.17 mm) as a single breath hold (0.52+/-0.20 mm) and were superior to multiple breath holds (1.22+/-0.60 mm). Affine NAV methods allowed for larger gating windows ( approximately 10 mm windows) with similar residual motion (0.74+/-0.17 mm). In this healthy adult cohort (N=10), free-breathing NAV methods offered respiratory motion suppression similar to a single breath hold.

Adolescent↗
PubMed1996

Detection of motion during tomographic acquisition by an optical flow algorithm.

An automatic procedure to detect and quantify patient motion during the acquisition of the tomographic views in single photon emission computerized tomography (SPECT) is proposed. This method first computes the optical flow vector field which assigns to each pixel of a tomographic view the two-dimensional displacement vector that describes its motion between two successive views. The average optical flow in a region of interest is then computed to measure its inter-view global motion. This algorithm is tested on a point source, on a cardiac phantom (with and without induced motion), and on a patient. The proposed method can accurately detect the presence of motion, localize the camera angle at which motion occurred, and measure the distance of motion. The optical flow method can be used to control the quality of the tomographic acquisition and to alert the user to the potential of reconstruction artifacts due to patient motion. It can also be used to correct for the translational motion in the direction of the axis of rotation of the camera.

Algorithms↗
PubMed2006

The impact of motion artifacts on the reproducibility of repeated coronary artery calcium measurements.

The purpose of this study is, using a 16-section multidetector-row helical computed tomography (MDCT) scanner with retrospective reconstruction, to compare variability in repeated coronary calcium scoring and qualitative scores of the motion artifacts. One hundred forty-four patients underwent two subsequent scans using MDCT. According to Agatston and volume algorithms, the coronary calcium scores during mid-diastole (the center corresponding to 70% of the R-R cycle) were calculated and the inter-scan variability was obtained. Motion artifacts from coronary artery calcium were subjectively evaluated and classified using a 5-point scale: 1, excellent; no motion artifacts; 2, fine, minor motion artifacts; 3, moderate, mild motion artifacts; 4, bad, severe motion artifacts; 5, poor, doubling or discontinuity. Each reading was done by vessels (left main, left descending, left circumflex and right coronary arteries) and the motion artifact score (mean of the scales) was determined per patient. The variability in the low (1.2+/-0.2) and high (2.4+/-0.6) motion artifact score groups was 7+/-6 (median, 6)% and 19+/-15 (16)% on the Agatston score (P<0.01) and 7+/-7 (6)% and 16+/-13 (14)% on the volume score (P<0.01), respectively. In conclusion, motion has a significant impact on the reproducibility of coronary calcium scoring.

Adult↗
PubMed1999

Identification of head motions by central vestibular neurons receiving linear and angular input.

Most naturally occurring displacements of the head in space, due to either an external perturbation of the body or a self-generated, volitional head movement, apply both linear and angular forces to the head. The vestibular system detects linear and angular accelerations of the head separately, but the succeeding control of gaze and posture often relies upon the combined processing of linear and angular motion information. Thus, the output of a secondary neuron may reflect the linear, the angular, or both components of the head motion. Although the vestibular system is typically studied in terms of separate responses to linear and angular acceleration of the head, many secondary and higher-order neurons in the vestibular system do, in fact, receive information from both sets of motion sensors. The present paper develops methods to analyze responses of neurons that receive both types of information, and focuses on responses to sinusoidal motions composed of a linear and an angular component. We show that each neuron has a preferred motion, but a single neuron cannot code for a single motion. However, a pair of neurons can code for a motion by the relative phases of firing-rate modulation. In this way, information about motion is enhanced by neurons combining information about linear and angular motion.

Animals↗
PubMed1976

Interventricular septal motion during preexcitation and normal conduction in Wolff-Parkinson-White syndrome: echocardiographic and electrophysiologic correlation.

Interventricular septal motion was studied by echocardiogram in 20 consecutive patients with documented Wolff-Parkinson-White (WPW) syndrome before and during electrophysiologic evaluation using His bundle recordings and pacing techniques. Characteristic abnormal interventricular septal motion was seen in 8 of 11 patients with type B WPW syndrome (groups I and II). All eight patients had electrocardiographic patterns consistent with an anomalous pathway located in the anterior right ventricular wall (group I). In five of these eight patients normalization of the QRS complex for one or more beats was accomplished and produced normalization of the septal motion in four; whereas in the fifth patient, who had an underlying atrial septal defect, the abnormal septal motion remained abnormal. All nine patients with type A WPW syndrome (groups III to V) had normal septal motion both during total preexcitation and during normalization of the QRS complex. The normalization of the abnormal interventricular septal motion with normalization of the QRS complex in type B WPW syndrome strongly suggests that the abnormal motion is related to an abnormal sequence of ventricular depolarization during preexcitation. Furthermore, persistent abnormal septal motion after normalization of the QRS complex suggests that other factors such as right ventricular volume overload may be responsible. Likewise, when abnormal septal motion occurs in the presence of type A WPW syndrome, an explanation other than preexcitation must be sought.

Adolescent↗