• Physical Therapy Korea
• /
• v.5 no.3
• /
• pp.42-47
• /
• 1998

Patients with hemiplegia usually show different body weight distribution as compared with normal subjects. Asymmetrical posture during static stance has been identified as a common problem in patients with hemiplegia. The purpose of this study was to identify the effects of vision and visual feedback on body weight distribution while standing under three conditions: eyes-closed, eyes-open and visual feedback condition. Fourteen patients with hemiplegia participated in the study. Their body weight distribution during standing for 20 seconds was measured by Limloader. The data were analysed by repeated measure of one-way ANOVA. The weight bearing on the paretic limb in the eyes-open condition was significantly higher than that of the eyes-closed condition. The weight bearing on the parietic limb in the visual feedback condition was significantly higher than that of the eyes-open condition. These results suggest that patients with hemiplegia can improve their symmetrical stance ability using visual feedback.

• The Journal of Korean Physical Therapy
• /
• v.33 no.3
• /
• pp.162-167
• /
• 2021

Purpose: A hyperextended knee is described as knee pain associated with an impaired knee extensor mechanism. Additionally, a hyperextended knee may involve reduced position sense of the knee joint that decreases the individual's ability to control end-range knee extension movement. The purpose of this study was to investigate the effects of visual biofeedback information for plantar pressure distribution on knee joint angle and lower extremity muscle activities in participants with hyperextended knees. Methods: Twenty-three participants with hyperextended knees were recruited for the study. Surface electromyography signals were recorded for the biceps femoris, rectus femoris, gastrocnemius, and tibialis anterior muscle activities. The plantar pressure distribution was displayed and measured using a pressure distribution measuring plate. Knee joint angle kinematic parameters were recorded using a motion analysis system. The visual biofeedback condition was the point at which the difference between the forefoot and backfoot plantar foot pressure on the monitor was minimized. The Wilcoxon signed-rank test was used to determine the significance between the visual biofeedback condition and the preferred condition. Results: The knee joint angle was significantly decreased in the visual biofeedback condition compared to that in the preferred condition (p<0.05). The rectus femoris and gastrocnemius muscle activities were significantly different between the visual biofeedback and preferred conditions (p<0.05). Conclusion: The results of this study showed that visual biofeedback of information about plantar pressure distribution is effective for correcting hyperextended knees.

• Physical Therapy Korea
• /
• v.19 no.3
• /
• pp.40-50
• /
• 2012

The purpose of this study was to investigate the effect of visual feedback on the postural control of stroke patients, by systematically varying conditions of visual feedback [eye-open condition (EO) vs. eye-closed condition (EC)], and base-support (both-side support, affected-side support, and unaffected-side support). In this study, we allocated 41 stroke patients with no damage in the cerebellum and visual cortex who can walk at least 10 meters independently, and 35 normal adults who have no experience of stroke to the control group. Both groups were asked to perform a "sit-to-stand" task three to five times, and their postural control ability was measured and compared in terms of asymmetric dependence (AD) instead of the traditional symmetric index (SI) in the literature. The results showed that although both subject groups maintained better postural control in the EO condition than in the EC condition, the patient group appeared to be more stable in EC than in EO when they were required to perform the task of the support condition given on the affected side. These results implied that visual feedback can impair stroke patients' postural control when it is combined with a specific support condition.

• Physical Therapy Rehabilitation Science
• /
• v.11 no.3
• /
• pp.296-303
• /
• 2022

Objective: In general, macular degeneration, cataracts and glaucoma generally cause visual injury in clinical settings. This study aimed to examine the effects of low visual acuity simulations on hand manual dexterity function and brainwaves in healthy young adults. Design: Cross-sectional study design Methods: This study was an observational, cross-sectional study. Seventy healthy young adults participated in this study. To evaluate the effects of low visual acuity simulations on hand function and brain waves, this study involved four different visual conditions including (1) normal vision, (2) simulated cataracts, (3) simulated glaucoma, and (4) simulated macular degeneration. The hand function was measured to use the Minnesota manual dexterity test (MMDT), and the brainwaves was also measured to use the electroencephalography. Results: In hand function, placing and turning performance on the MMDT in the normal visual condition was significantly different than that in the cataract and macular degeneration conditions (p<0.05), and the placing performance was significantly differred in the normal condition than that in the simulated glaucoma. However, turning was not significantly different in the normal condition than that in the simulated glaucoma. The alpha, beta, and gamma waves did not significantly differ among the four visual conditions (p>0.05). Conclusions: The results suggest that limited visual information negatively affects the ability to perform tasks requiring arm-hand dexterity and eye-hand coordination. However, the effectiveness of low visual acuity on the brainwaves should be further studied for rehabilitative evidence of visual impairment.

• Journal of the Korean Society of Physical Medicine
• /
• v.18 no.3
• /
• pp.47-53
• /
• 2023

PURPOSE: A visual feedback method was proposed to induce brain stimulation in a stroke patient, and among them, there was a treatment using a mirror. On the other hand, mirror therapy focuses only on the functional changes in body movements, and analysis of neurophysiological mechanisms of brain activity is lacking. In addition, studies on evaluating the activity and response generated in specific brain regions during visual feedback training using mirrors are insufficient. METHODS: Fifteen healthy adults (male: 10, female: 5, Years: 23.33 ± 1.23), who were right-handed were recruited. By attaching the C3, Cz, and C4 channels in the sensorimotor cortex using an electroencephalogram, training was performed under the conditions without mirror-based visual feedback (No-condition) and with visual feedback (Tasks-condition). At this time, the immediate activity of the mu-rhythm in response to training was separated and evaluated. RESULTS: The tasks-condition of C3, Cz, and C4 channels activated the relative mu-rhythm rather than the no-condition, and all showed significant differences (p < .05). In addition, in all channels at the start time, the tasks-condition was more active than the no-condition (p < .05). The activity of the cortical response was higher in the tasks-condition than in the no-condition (p < .05). CONCLUSION: The mu-rhythm activity can be evaluated objectively when visual feedback using a mirror is applied to healthy subjects, and a basic analysis protocol is proposed.

• International Journal of Internet, Broadcasting and Communication
• /
• v.12 no.3
• /
• pp.226-232
• /
• 2020

Repetition of landing with visual control in sports and training is common, yet it remains unknown how landing with visual control affects postural stability and lower limb kinetics. The purpose of this study was to test the hypothesis that landing with visual control will influence on lower limb control for intrinsic dynamic postural stability. Kinematics and kinetics variables were recorded automatically when all participants (n=10, mean age: 22.00±1.63 years, mean heights: 177.27±5.45 cm, mean mass: 73.36±2.80 kg) performed drop landings from 30 cm platform. Visual control showed higher medial-lateral force, peak vertical force, loading rate than visual information condition. This was resulted from more stiff leg and less time to peak vertical force in visual control condition. Leg stiffness may decrease due to increase of perturbation of vertical center of gravity, but landing strategy that decreases impulse force was shifted in visual control condition during drop landing. These mechanism explains why rate of injury increase.

• Physical Therapy Rehabilitation Science
• /
• v.6 no.3
• /
• pp.140-145
• /
• 2017

Objective: The purpose of this study was to investigate the effect of visual block with ankle joint fatigue on gait and dynamic balance ability. Design: Cross-sectional study. Methods: Thirty healthy young adults (men=15, women=15) between 22 to 25 years of age voluntarily participated in this study. All subjects performed the gait and dynamic balance test successively in two conditions: the visual block and the open eyes condition. Before the gait and dynamic balance test, muscle fatigue on the ankle joint was induced to all subjects by doing ankle dorsiflexion and plantarflexion alternately, and then gait parameters (step length, stride length, cadence, velocity, single limb support, and double limb support) were assessed by walking on the GAITRite system (CIR Systems Inc., USA). Subjects also performed the functional reach test (FRT) for assessment of dynamic balance. This study examined gait parameters and FRT scores in each visual block and open eyes condition. Results: The results showed that FRT scores with the visual block condition significantly decreased compared to without visual blocking (p<0.01). Step length, stride length, cadence, and velocity of gait parameters decreased significantly in the visual block condition (p<0.01) while there was no significant difference for single limb support. However, double limb support increased significantly in the visual block system (p<0.01). Conclusions: Therefore, blocking of visual information with muscle fatigue of the ankle joint can affect gait and balance ability of young adults and increase the risk of falls.

• Korean Journal of Cognitive Science
• /
• v.16 no.1
• /
• pp.1-15
• /
• 2005

Since human visual system has limited capacity for visual information processing, it should select goal-relevant information for further processing. There have been several studies that emphasized the possible involvement of memory in spatial shift of selective attention (Chun & Jiang, 1998, 1999; Klein, 1988; Klein & MacInnes, 1999). However, other studies suggested the inferiority of human visual memory in change detection(Rensink, O'Regan, & Clark, 1997; Simons & Levin, 1997) and in visual search(Hotowitz & Wolfe, 1998). The present study examined the involvement of memory in visual search; whether memory for the previously searched items guides selective attentional shift or not. We investigated how search works by comparing visual search performances in three different conditions; full exposure condition, partial exposure condition, and partial-to-full exposure condition. Revisiting searched items was allowed only in full exposure condition and not in either partial or partial-to-full exposure condition. The results showed that the efficiencies of attentional shift were nearly identical for all conditions. This finding implies that even in full exposure condition the participants scarcely re-examined the previously searched items. The results suggest that instant memory can be formed and used in visual search process. These results disagree with the earlier studies claiming thar visual search has no memory. We discussed the problems of the previous research paradigms and suggested some alternative accounts.

• Journal of Korean Institute of Industrial Engineers
• /
• v.23 no.3
• /
• pp.533-544
• /
• 1997

Among numerous factors that have an effect on visual field, the effects of background condition on the size of the visual field were investigated to obtain more practical visual field that can be readily applicable to industrial settings. A visual experiment was conducted, in which the subject was instructed to search a target with distinct orientations. Size contrast, meridian, nontarget density, and subject's gender showed a significant effect on the size of the visual field at $\alpha=0.01$. The size of the visual field was linearly proportional to size contrast, and inversely proportional to density. Female's visual fields were found to be significantly larger than male subjects', The size of the visual field on horizontal axis was larger than that on vertical axis, and the size of the head & eye field on right meridian was also larger than that on left meridian. The shape was found to be horizontally oriented oval and statistically asymmetric with respect to horizontal and vertical axes. The regression equations to predict the visual fields on the given background condition were suggested. The visual fields suggested in this study would be valuable to the design of visual displays and the panel layout of various displays and controls.

• Journal of Broadcast Engineering
• /
• v.18 no.4
• /
• pp.589-598
• /
• 2013

In order to understand 3D visual fatigue, it is necessary to examine the visual fatigue induced by camera parameters as well as that induced by a pre-existing 3D content. In the present study, we examined the effects of camera parameters, such as roll misalignment error, shooting distance and vergence condition on 3D visual fatigue and we modelled it. The results indicate that roll misalignment error, shooting distance and vergence condition affect 3D visual fatigue and the effect of roll misalignment error on 3D visual fatigue is evident specifically when screen disparity is relatively small.