重心動揺検査の検討 検査条件について

This study examined the interrelationships between various parameters evaluating body sway from the center of foot pressure (CFP) during a static standing posture, and gender difference by domain. The subjects were 220 healthy young males and females. CFP was measured 3 times with a 1 min rest, and the mean of trials 2 and 3 was used for the analysis. The measurement device was Anima's stabilometer G-5500. Data sampling frequency was 20Hz. Sixty parameters with higher reliability were selected from the following 7 domains: distance, center average, distribution of amplitude, area, velocity, power spectrum, and body sway vector.Several parameters showed a significant gender difference, but the degree was not large. The correlation coefficients between parameters in each domain of distance, center average, distribution of amplitude, area, velocity, and body sway vector were very high, and they tended to relate closely to some parameters in the other domains. Gender difference in the correlation coefficient was insignificant. Therefore, the relationship between parameters in both genders was judged to be very similar.After examining the interrelationship between parameters, 36 parameters were selected. We judged that the body sway can be synthetically evaluated by these rather than 60 parameters.

With a micro-computer-gravicorder SG-1, the Length/Time (LNG/T), Root Mean Square (RMS) and Standard Deviation Area (SD-Area) of body sway were analyzed automatically in 14 kinds of visual and somatosensory condition. The test was done in 22 normal subjects (NS) and 55 patients with vertebrobasilar insuffiency who were classified into 6 groups by the results of caloric testing.Eighteen kinds of calculation and statistical analyses were done with a computer to compose NS and each patient group. All the groups showed different chara-cteristic body sways under different external condi-tions.1) In the NS group, body sway in the dark>body sway while looking at OKN>body sway while watching LED≅body sway in the light.2) In group A, the SD-Area of body sway while watching LED was larger than in the dark on the S-G board.3) In group B, the RMS and the SD-Area in the dark was smaller than while looking at OKN, while watching LED or in the light on the S-G board. The RMS while watching LED was larger than in the dark or while looking at OKN on the flat board.4) In group D, the LNG/T while watching LED was larger than while looking at OKN on both boards.5) In group E, there were no characteristic findings. With those tests, we could demonstrate the effects of visualvestibular-somatosensory interactions on body sway.

Viewing angle effects from wide field video projection images on the human equilibrium

The role of static and kinetic visual information in the regulation of the upright standing position was studied in 7 healthy subjects.The subject stood on a stabilometer with the feet close together and gazed at the visual pattern (11 vertical stripes drawn at intervals of 4 cm). The postural sway under normal illumination, stroboscopic illumination at a frequency of 10 Hz, 5 Hz, and 1.4 Hz, and in darkness was recorded for 30 seconds with an X-Y recorder and stored in the disk of a microcomputer. On the basis of the stored data, concerning the area, unit locus length, forward-backward and right-left diameters, standard deviation, skewness and kurtosis of amplitude, the probability density distribution and power spectrum were calculated by a specially designed program.1. The size of body sway under stroboscopic illumination at a frequency of 1.4 Hz was larger than in the dark. Examinations related to sway-area, for-ward-backward and right-left diameters, and standard deviation of amplitude probability density distribution showed similar results.2. Kurtosis tended to be small under stroboscopic illumination at a frequency of 1.4 Hz.3. The rate of low frequency (0.033-0.195 Hz) in the power spectra of body sway under stroboscopic illumination at a frequency of 1.4 Hz was larger than in the dark.Static visual information without kinetic visual information caused destabilization of posture regulation. Kinetic visual information plays a major role in visual control in the upright standing position, especially in the control of body sway at low frequency.

Recordings were made from striate cortex in five groups of cats that had been raised with strabismus produced by sectioning the extraocular muscles. These groups included animals reared with exotropia, unilateral or bilateral esotropia, and esotropia combined with lid suture of the unoperated eye. In addition, a group of esotropes was studied in which the unoperated eye was removed a few hours prior to recording. For comparison, five normal adult cats were also studied. In each of the above groups, cells were sampled in the representations of the central and peripheral visual fields in area 17 ipsilateral and contralateral to the deviated eye. We mapped the receptive field of each responsive cell, determined its ocularity, and tested it for selectivity. Confirming previous work, we found a marked loss of cortical binocularity in cats raised with strabismus. On average only 7% of the neurons that we recorded could be driven by both eyes. This percentage was relatively constant at all cortical locations that were studied and was not influenced by whether cats had been reared with exotropia, unilateral esotropia, or bilateral esotropia. The percentage of selective cells driven by the deviated eye in exotropes or esotropes did not appear to be different from normal at most cortical locations (but see 5, below). In addition, we did not observe any bias in the axial preference of selective cells in strabismic cats when compared with normal adult cats. In both exotropes and esotropes the deviated eye drove fewer cells when compared with the proportion that are driven by one eye in normal cats. In exotropes this deficit did not vary at different cortical representations of the visual field. In esotropes, however, this deficit was graded, being least in the representation of the peripheral visual field in area 17 contralateral to the deviated eye, intermediate in the representations of the central visual field in the contralateral and ipsilateral hemispheres, and greatest in the representation of the peripheral visual field in ipsilateral area 17. Furthermore, only when recording from the peripheral field representation in the ipsilateral hemisphere did we encounter significant numbers of cells driven by the deviated eye that lacked normal selectivity. Since it is possible that deprivation of the converged eye during development might account for the deficits noted above, we attempted to evaluate this factor using several independent lines of evidence. First, we could find no correlation between the angle of esotropia and the ability of the deviated eye to drive ipsilateral cortical cells representing the peripheral visual field.(ABSTRACT TRUNCATED AT 400 WORDS)

Task-determined strategies of visual process

Body sway in patients standing with eyes closed was observed by tilting the plate toward the front, back, left, and right. Patients with equilibrium dysfunction produced a specific body sway under these conditions. It is shown that merely standing on the flat plate does not always show a specific pattern even in patients with equilibrium dysfunction. However, for subjects standing on the tilting plate, it is possible to discriminate equilibrium disorders from normals. Eight directional display and a power spectrum of body sway are useful for the diagnosis of equilibrium dysfunction. Abnormal subjects show a peculiar pattern in the radar chart display of displacement, and the power spectrum of body movement does not obey the rule of 1/f fluctuation. >

A feedback control process based on self-motion perception contributes to postural stability; however, little is known about the visual modulation of postural muscles. The aim of this study was to investigate the effect of optic flow stimuli, presented full field, in the peripheral and foveal visual field, on muscular activation. Then, we assessed the correlation between optic flow, muscle activity and body sway in male and female subjects. We used surface electromyography (EMG) and stabilometry on 24 right-handed young adults. We recorded the bilateral activation of tibialis anterior, gastrocnemius medialis, biceps femoris and vastus medialis. EMG and center of pressure (COP) signals were acquired simultaneously. EMG signal amplitude was computed as root mean square normalized by baseline. We found a significant effect for muscles, gender and an interaction effect of muscle by gender (ANOVA, p < 0.001). Results showed different postural alignments in males and females. The COP spatial variability during peripheral stimuli was generally reduced. The prevalent direction of oscillation evoked by peripheral stimuli was clustered, while foveal and random stimuli induced distributed and randomized directions. Also for muscle activity, we found gender differences in the prevalent oscillation distributions evoked by optic flow. Visual stimuli always evoke an excitatory input on postural muscles, but the stimulus structure produces different postural effects. Peripheral optic flow stimuli stabilize postural sway, while random and foveal optic flow provoke larger sway variability similar to those evoked in the absence of visual stimulation.

Adequate cerebral perfusion is necessary to maintain consciousness in the upright human. Following maximal anaerobic exercise, cerebral perfusion can become compromised as evident by post‐exercise syncope. It is unknown whether post‐exercise reductions in cerebral perfusion after exercise lead to cognitive deficits prior to the onset of syncope, which would be of utmost concern in populations such as emergency workers and soldiers. Therefore, the purpose of this experiment was to determine if reductions in cerebral blood flow velocity induced by maximal anaerobic exercise and head up tilt lead to visual/cognitive deficits prior to the onset of syncope. We hypothesized that a modified Wingate test followed by a head‐up tilt would reduce cerebral blood flow velocity and result in visual/cognitive deficits prior to the onset of syncope. Ten recreationally active volunteers were subjected to a symptom‐limited 60° head‐up tilt for up to 16 min before and after a 60‐s Wingate test. Blood flow velocity of the middle cerebral artery was measured via transcranial Doppler ultrasound and a visual decision‐reaction time test was assessed in the peripheral visual field. Cerebral blood flow velocity decreased as tilt progressed from 49.6 ± 3.2 to 46.2 ± 2.4 cm/s (mean ± SE; p &lt; 0.05). Also, peripheral decision‐reaction time increased as tilt progressed from 363.7 ± 12.7 to 385.3 ± 18.4 ms (p &lt; 0.05). These data suggest that the reduction in cerebral blood flow velocity following maximal anaerobic exercise contributes to cognitive deficits as evidenced by the concurrent increase in peripheral field decision‐reaction time prior to syncope.Support provided by NIH grant HL115027

The visual navigation system in this paper models the human visual system and utilizes the well-known physiological concepts of peripheral vision and central vision fields to conduct image processing separately and to integrate the results from these processes. With this system, we attempt to realize an efficient image processing method. The peripheral vision field, which has a low resolution, rapidly detects the presence of the object of interest from the scene, and is able to deal with differences in the size and shape of the object brought about by a change in the viewpoint. Because of its speed and its capability in dealing with ambiguities, such as analogy and association, a three-layer neural network is utilized here to realize this function. On the other hand, the central vision field focuses on the object detected by the peripheral vision field and zooms in on the candidate to check it further. If the object detected is adjudged to be the object of interest, the robot's visual navigation system computes the direction and the distance towards the object using the algorithm to be introduced here that extracts three-dimensional (3D) vectors from 2D coordinates. Great demand is seen for such machines in the near future.

In previous studies, many evaluation parameters for the center of foot pressure (CFP) in a static standing posture have been proposed, but their reliability and inter-relationships have not been sufficiently examined.The purposes of this study were to examine trial-to-trial reliability and the inter-relationships of various evaluation parameters and to propose useful ones. Thirty healthy young adults were selected as subjects. The measurement of CFP for 1 minute was carried out 10 times with 1 minute rest for each subject. The measurement device was an Anima's stabilometer G5500. The data was recorded every 20 msec. Seventy-six evaluation parameters, excepting composite parameters from 114 parameters proposed in previous studies, were selected from the following domains: distance, center of pres-sure, distribution of amplitude, area, velocity, power spectrum, and vector for body sway. The intraclass correlation coefficients (ICC) for 10 trials were 0.7 or over for all parameters excepting for the X-axis and the Y-axis distribution for body sway, and skewness and kurtosis for body sway speed, but a significant difference between the first trial and the other trials was found in many parameters. Therefore, the ICC was recal-culated by excluding the first trial. As a result, no significant difference was found other than that of the distance of the root of the mean square and the area of the root of the mean square. The ICC was 0.7 or over, excepting for the following parameters: the X-axis and the Y-axis distribution for body sway and skewness and kurtosis for body sway speed, the cross correlations for body sway and body sway speed, the C ratio of the power spectrum area on the X-axis, the A ratio of the power spectrum area on the Y-axis and the root of the mean square-axis. Inter-correlation coefficients between parameters in each domain of distance, center of pressure, distribution of amplitude, area, velocity, power spectrum, and vector for body sway were mostly high values of 0.9 or over. Thus, it was considered that there is a close relationship between theoretically similar parameters and any of them could be selected as useful parameters.Based on the above-stated examination, 60 evaluation parameters shown in Table 5 were finally selected.

Stereoscopic imaging techniques have also become used for not only amusement but also in the industrial, medical care, and educational fields, however, symptoms due to the stereopsis have been reported. In this study, we especially focus on the effect of background motions on the equilibrium function. The body sway was recorded while/after viewing a sphere as a visual target synchronized/unsynchronized with periodic motion of the view point. Statistical analysis was conducted for the stabilograms.

Postural stability is an important measure for many medical diseases such as Parkinson. In the last years, research focused on using inexpensive and portable devices to measure postural stability, while the visual targets were physical objects in the environment. Sensing balancing boards were used to measure stance forces, while movements of the upper body were not taken into account. Within this paper, postural stability was measured using the HTC Vive. A variation of a virtual fixation point's distance was analyzed and compared to a reference condition with closed eyes. It is shown that body sway in the VR conditions is increased in the anterior-posterior and decreased in the medial-lateral direction.

This study was done to examine age-stage (preschool children, young adults, and elderly people) differences in the center-of-pressure sway using body-sway factors (unit-time sway, front-back sway, left-right sway, and high frequency-band power), power-spectrum distribution, and relative accumulation of power frequency (25%, 50%, and 75% RAPF) of the center-of-pressure spectrum. The center-of-pressure movement for 1 min. was measured twice using Anima's stabilometer. Data-sampling frequency was set at 20 Hz. Significant age-stage differences were found for 3 factors except for left-right sway, which was larger for preschool children and elderly than for young adults. The power spectrum of body sway in any age-stage was noted mainly in low frequency bands. A marked age-stage difference was found at 75% RAPF. Body-sway characteristics in each age-stage differ, and differences of postural-sway frequency are marked in the low frequency bands.

Topiramate associated non-glaucomatous visual field defects