• Journal of Biomedical Engineering Research
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• v.17 no.4
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• pp.417-426
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• 1996

In this paper, we report the effects of visual stimulation patterns in the postural balance control. We used the motor-driven cloth panel and HMD(Head Mounted Display) to evaluate the effect of visual stimulation patterns in the postural balance control. We also investigated the usefulness of HMD in the postural balance rehabilitation training system from the view of reducing the scale of experimental system. Our results showed that a vertical-strip visual pattern was more effective than the others in the postural balance control. It was also indicated that HMD might be applied to clinical use as a new postural balance training system.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.3
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• pp.221-227
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• 2009

For successful restoration of visual function by a visual neural prosthesis such as retinal implant, electrical stimulation should evoke neural responses so that the informat.ion on visual input is properly represented. A stimulation strategy, which means a method for generating stimulation waveforms based on visual input, should be developed for this purpose. We proposed to use the decoding of visual input from retinal ganglion cell (RGC) responses for the evaluation of stimulus encoding strategy. This is based on the assumption that reliable encoding of visual information in RGC responses is required to enable successful visual perception. The main purpose of this study was to determine the influence of inter-dependence among stimulated RGCs activities on decoding accuracy. Light intensity variations were decoded from multiunit RGC spike trains using an optimal linear filter. More accurate decoding was possible when different types of RGCs were used together as input. Decoding accuracy was enhanced with independently firing RGCs compared to synchronously firing RGCs. This implies that stimulation of independently-firing RGCs and RGCs of different types may be beneficial for visual function restoration by retinal prosthesis.

• Journal of Korean Academy of Nursing
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• v.30 no.1
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• pp.98-109
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• 2000

The purpose of this study was to identify the effect on improvement of the Activity of Daily Living (ADL) and decrease the cognitive function and agitation behaviors by reminiscence with audio-visual stimulation for senile dementia. The quasi-experimental design was used in this study. Subjects were 26 with mild senile dementia who were cared for at a Day Care Center for Dementia in Seoul. The data were collected from March to July, 1999. Subjects were divided into three groups : Control Igroup with 10 subjects, reminiscence group(Control II group with 8 subjects), and reminiscence with audio-visual stimulation group(experimental group with 8 subjects). The Control I group got routine care as usual. Control II group participated in reminiscence sessions for one hour a day, five times a week , for a period of 4 weeks. The experimental group participated in reminiscence with audio-visual stimulation sessions for one hour a day, five times a week, for a period of 4 weeks. Instruments of this study were color photography with sound that was developed through an open questionnaire about events, objects, humans in action and animals that 100 Korean elderly over 60 would like to memorize. This was referred from the Sensory Stimuli Package by Namazi and Haynes(1994). The effects of treatment was evaluated through MMSE-K by Kwon & Park(1989). Also the Brief Cognitive Rating Scale(BCRS) by Reisberg et al(1983) for the cognitive function, through Agitation Inventory by Cohen- Mansfield and Colleague(1989) for behavioral response and through the Rapid Disability Rating Scale-2(RDRS-2) by Linn & Linn(1982) for the activity of daily living respectively. Data analysis was done using SPSS for $\chi$2- test, ANOVA, repeated measures ANOVA. The results were as follows : 1. Reminiscence with audio-visual stimulation did not improve cognitive function for senile dementia, but significantly improved verbal expression, the subscale of cognitive function. 2. Reminiscence with audio-visual stimulation reduced agitation behavior of experimental group significantly, but there was no significant difference between groups. 3. Reminiscence with audio-visual stimulation did not significantly effect the activity of daily living after treatment. In conclusion, it was shown that the reminiscence with audio-visual stimulation was an effective therapy to improve verbal expression and to reduce agitation behaviors of senile dementia. Further research with more indepth approach is needed, considering characteristic and level individualized for each senile dementia.

• Journal of Biomedical Engineering Research
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• v.30 no.4
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• pp.347-354
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• 2009

For the reliable transmission of meaningful visual information using prosthetic electrical stimulation, it is required to develop an effective stimulation strategy for the generation of electrical pulse trains based on input visual information. The characteristics of neuronal activities of retinal ganglion cells (RGCs) evoked by electrical stimulation should be understood for this purpose. In this study, for the development of an optimal stimulation strategy for visual prosthesis, we analyzed the neuronal responses of RGCs in rd1 mouse, photoreceptor-degenerated retina of animal model of retinal diseases (retinitis pigmentosa). Based on the in-vitro model of epiretinal prosthesis which consists of planar multielectrode array (MEA) and retinal patch, we recorded and analyzed multiunit RGC activities evoked by amplitude-modulated electrical pulse trains. Two modes of responses were observed. Short-latency responses occurring at 3 ms after the stimulation were estimated to be from direct stimulation of RGCs. Long-latency responses were also observed mainly at 2 - 100 ms after stimulation and showed rhythmic firing with same frequency as the oscillatory background field potential. The long-latency responses could be modulated by pulse amplitude and duration. From the results, we expect that optimal stimulation conditions such as pulse amplitude and pulse duration can be determined for the successful transmission of visual information by electrical stimulation.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.6
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• pp.443-448
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• 2009

For successful visual perception by visual prosthesis using electrical stimulation, it is essential to develop an effective stimulation strategy based on understanding of retinal ganglion cell (RGC) responses to electrical stimulation. We studied RGC responses to repetitive electrical stimulation pulses to develop a stimulation strategy using stimulation pulse frequency modulation. Retinal patches of photoreceptor-degenerated retinas from rd1 mice were attached to a planar multi-electrode array (MEA) and RGC spike trains responding to electrical stimulation pulse trains with various pulse frequencies were observed. RGC responses were strongly dependent on inter-pulse interval when it was varied from 500 to 10 ms. Although the evoked spikes were suppressed with increasing pulse rate, the number of evoked spikes were >60% of the maximal responses when the inter-pulse intervals exceeded 100 ms. Based on this, we investigated the modulation of evoked RGC firing rates while increasing the pulse frequency from 1 to 10 pulses per second (or Hz) to deduce the optimal pulse frequency range for modulation of RGC response strength. RGC response strength monotonically and linearly increased within the stimulation frequency of 1~9 Hz. The results suggest that the evoked neural activities of RGCs in degenerated retina can be reliably controlled by pulse frequency modulation, and may be used as a stimulation strategy for visual neural prosthesis.

• Journal of the Ergonomics Society of Korea
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• v.18 no.3
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• pp.27-39
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• 1999

The purpose of this study was to approve the capability of human sensibility evaluation based on physiological responses and real-time subjective assessments. Three well-trained healthy human subjects were participated in the experiments. We measured physiological responses such as Heart Rate Variability(HRV), Galvanic Skin Response(GSR) and skin temperature under rest and visual stimulation conditions, respectively. Off-time subjective assessments were recorded before and after visual stimulations. Real-time subjective assessments were recorded during visual stimulations. The results of physiological responses and off-time and real-time subjective assessments were quantified and compared. The results showed that the correlation between physiological responses and real-time subjective assessments was high (83%) for both the positive and negative visual stimulation. The correlation between the physiological responses and off-time subjective assessments was high (83%) for the negative visual stimulation but was low (15%) for the positive visual stimulation. Although the current observation is preliminary and requires more careful experimental study, it appears that the correlation between real-time subjective assessment and physiological responses is higher than that of the off-time subjective assessment and physiological responses.

• The Journal of Korean society of community based occupational therapy
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• v.7 no.1
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• pp.1-8
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• 2017

Objective : The purpose of this study was to identify the effect of vestibular stimulation activity on visual perception. Methods : A total of 58 healthy adults in chungnam was participated in this study. I divided into the total 3 groups and studied. Group A was no vestibular stimulation, they sat on general chair and performed the visual perception task. Group B and C sat on general chair and ball chair respectively, after vestibular stimulation activity and they performed visual perception task. I measured the visual perception task with the time. Results : There was a significant difference between Group A and B and C. There was no significant difference between group B and C. Conclusion : The result shows that the vestibular stimulation activity is effective for an improvement in visual perception.

• Investigative Magnetic Resonance Imaging
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• v.3 no.1
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• pp.41-46
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• 1999

Purpose : To investigate the difference of total activation in visual area, motor area, and cerebellum according to the stimulation paradigm. Materials and Methods : Functional MR imaging was performed in 5 healthy volunteers with visual and motor activity using EPI technique. LED and Checker-Board stimulation were performed for visual activity. Thumb motion and Finger Tapping were performed for motor and cerebellum activity. Stimulus timing was 60sec. off, 120sec. on, 60sec. off. Data processing was carried out by using the cross-correlation method for each pixel. Each pixel was then selected and assumed activated if the correlation coefficient was equal or larger than a threshold value. Time course data was obtained by calculating the total activation which was defined as the number of activated pixel x averaged pixel intensity. Results : In the case of visual activity with LED stimulation, we found increased total activity of more than 100% compared with Checker-Board stimulation. In the case of motor area and cerebellum with Finger tapping stimulation, we found increased total activity of more than 10% and 150%, respectively compared with Thumb motion stimulation.

• Ocean Systems Engineering
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• v.7 no.1
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• pp.39-51
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• 2017

Fishes detect various sensory stimuli, which may be used to direct their behavior. Especially, the visual and water flow detection information are critical for locating prey, predators, and school formation. In this study, we examined the specific role of these two different type of stimulation (vision and vibration) during the obstacle avoidance behavior of carp, Cyprinus carpio. When a visual obstacle was presented, the carp efficiently turned and swam away in the opposite direction. In contrast, vibration stimulation of the left or right side with a vibrator did not induce strong turning behavior. The vibrator only regulated the direction of turning when presented in combination with the visual obstacle. Our results provide first evidence on the innate capacity that dynamically coordinates visual and vibration signals in fish and give insights on the novel modulation method of fish behavior without training.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1999.03a
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• pp.237-242
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• 1999

The nature of the interactions between the vestibular and autonomic systems is complex and has not been fully defined. Vestibuloocular reflex induced by sinusoidal rotation and activity of the autonomic nerves in the heart were measured to investigate the interactions between the vestibular system and the autonomic nervous system in healthy adults. Eye movement induced by sinusoidal rotation of the whole body or optokinetic stimulation at 0.04 Hz was analyzed in gain, phase, and symmetry. EKG was measured during vestibular stimulation and analyzed in heart rate variability including mean R-R interval, standard deviation (SD) and coefficient of variance (CV) of R-R interval, and power spectrum of low frequency region (LF) and high frequency region (HF). Gain of eye movement was 0.65${\pm}$0.03 by ratatory stimulation, 0.70${\pm}$0.02 in optokinetic stimulation, 0.08${\pm}$0.02 in visual suppression, and 0.84${\pm}$0.04 in visual enhancement. In R-R interval, resting condition (control) was 0.82${\pm}$0.03 sec, and visual suppression showed significant increase and visual enhancement did significant decrease compared with control (p<0.01).CV was 0.06${\pm}$0.02 in control and visual enhancement increased significantly (p<0.05). In LF/HF control was 1.40${\pm}$0.23, which was not different from rotatory or optokinetic stimulation. But visual suppression decreased LF/HF significantly and visual enhancement increased significantly compared with control (p<0.01). These results suggest that degree of gain corresponds with LF/HF and increased gain in visual enhancement is deeply related to the activity of sympathetic nerves.