• 대한의용생체공학회:의공학회지
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• 제30권4호
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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.

• 대한인간공학회지
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• 제31권6호
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• pp.785-791
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• 2012

Objective: The aim of this study was to investigate the correlation between 3D visual fatigue and physiological measures by canonical correlation analysis enabling to categorical correlation. Background: Few studies have been conducted to investigate the physiological mechanism underlying the visual fatigue caused by processing 3D information which may make the cognitive mechanism overloaded. However, even the previous studies lack validation in terms of the correlation between physiological variables and the visual fatigue. Method: 9 Female and 6 male subjects with a mean age of $22.53{\pm}2.55$ voluntarily participated in this experiment. All participants were asked to report how they felt about their health sate at after viewing 3D. In addition, Low & Hybrid measurement test(Event Related Potential, Steady-state Visual Evoked Potential) and for evaluating cognitive fatigue before and after viewing 3D were performed. The physiological signal were measured with subjective fatigue evaluation before and after in watching the 3D content. For this study suggesting categorical correlation, all measures were categorized into three sets such as included Visual Fatigue set(response time, subjective evaluation), Autonomic Nervous System set(PPG frequency, PPG amplitude, HF/LF ratio), Central Nervous System set(ERP amplitude P4, O1, O2, ERP latency P4, O1, O2, SSVEP S/N ratio P4, O1, O2). Then the correlation of three variables sets, canonical correlation analysis was conducted. Results: The results showed a significant correlation between visual fatigue and physiological measures. However, different variables of visual fatigue were highly correlated to respective HF/LF ratio and to ERP latency(O2). Conclusion: Response time was highly correlated to ERP latency(O2) while the subjective evaluation was to HF/LF ratio. Application: This study may provide the most significant variables for the quantitative evaluation of visual fatigue using HF/LF ratio and ERP latency based human performance and subjective fatigue.

• 대한의용생체공학회:의공학회지
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• 제22권3호
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• pp.259-267
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• 2001

The visual evoked potentials(VEPs) is used to assist in the diagnosis of specific disorders associated with involvement of the sensory visual pathways. The P100 latency is an important parameter which is diagnosis of optic nerve disorders. There are characteristics of latency delay, wave distortion, amplitude deduction in abnormal subjects. It is difficult to diagnose in the case of producing peak at the P100 latency. In this paper, difference of pattern between normal VEPs and abnormal VEPs using the Choi-Williams distribution method is studied. We observed the relationship about time and spectrum. The result shown that normal VEPs had maximum spectral value at 20Hz~26.7Hz and abnormal VEPs had maximum spectral value at 16.7Hz~20Hz. Also normal VEPs spectrum is higher than abnormal VEPs spectrum.

• Journal of Korean Neurosurgical Society
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• 제29권5호
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• pp.635-639
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• 2000

Objective : Surgery for the microvascular decompression is mostly concerned with injury to the cranial nerves or brain stem by cerebellar retraction. Intraopeartive brain stem auditory evoked potentials(BAEPs) has been continuously monitored on surgery to evaluate the extent of injury, recovery of the nerves and prognosis. Methods : Of the 161 cases of CP angle surgery from Feb. 1996 to Apr. 1998, 103 cases were monitored during operation. Thirty five patients who had undergone similar surgery were selected and evaluated ; 23 patients were monitored and 12 were not during surgery. If monitor showed more than 0.5 mSec delay of latency, surgeon was given a warning not to retract brain any more. If more than 1mSec delay, surgeon was informed to stop surgery and wait for the returning of evoked potentials. The level of amplitudes and delay of latencies during the initial stage of operation, opening the dura, insertion of teflon patches, and closing the dura and recovery were then compared. Resuls : Twenty patients were male and 15 were female. Their average age was 50.26 years. Mean amplitude during the initial stage of operation was $0.60{\pm}0.25mV$, at opening the dura $0.56{\pm}0.26$, after teflon patches insertion $0.49{\pm}0.20$, and after closure of dura $0.47{\pm}0.28mV$. Mean latency during the early stage of operation was $6.08{\pm}0.67mSec$, at opening of dura $6.38{\pm}0.55$, insertion of teflon $6.97{\pm}0.59$, and closing the dura $6.17{\pm}0.54$. There was statistical significance in the difference of amplitudes between each procedures, and in the difference of latencies. For the complete recovery of amplitude and latency, it usually took average 5.65 minutes(0-20 min). In monitored group, only one patient required more than 20 minutes to recover and suffered from hearing disturbance after surgery. Others were recovered within 10 minutes without complications. However, 4 out of 12 patients who were not monitored showed hearing disturbance, and 1 patient had temporary facial palsy and dizziness(p＝0.000). Conclusion : The results indicate that continuous intraoperative monitoring of BAEPs during CP angle surgery is seen mandatory procedure to prevent operative complications.

• Journal of information and communication convergence engineering
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• 제8권2호
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• pp.234-237
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• 2010

P300 component of the event-related potential(ERP) has been studied for theoretical, empirical, and clinical applications. Nowadays the 1-, 2-, and 3-stimulus oddball paradigms are used for eliciting P300 component of EEG in the auditory stimulus experiments. In this paper, we used a method to add one more stimulus to the 3-stimulus auditory paradigm. The adding stimulus has not the same volume but the same tone of the target stimulus. The 4-stimulus oddball paradigm to use two targets is used to elicit the P300 event-related potentials. In 4-stimulus oddball paradigm, an infrequent non-target (p=0.10) is presented in addition to two infrequent targets (p=0.10) and a frequent standard (p=0.70). Two target stimuli elicited a P300 component with a parietal maximum distribution. The amplitude of the P300 in target 2 was larger than that in target 1 and the latency of the P300 in target 2 was longer than that in target 1. The P300 component due to target 2 stimuli was larger than that due to target 1 stimuli. The experimental results approve that the 4-stimulus oddball paradigm can elicit P300 component clearly. The results are compared with the results of the traditional oddball paradigm.

• Journal of Magnetics
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• 제20권4호
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• pp.427-431
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• 2015

The aim of this study was to investigate whether repetitive transcranial magnetic stimulation (rTMS) can improve motor recovery in the lower extremities of the patients with subacute stage spinal cord injury (SCI). This study was conducted with 19 subjects diagnosed with paraplegia because of SCI. The experimental group included 10 subjects who underwent active rTMS, and the control group included 9 subjects who underwent sham rTMS. The SCI patients in the experimental group underwent conventional rehabilitation therapy, and active rTMS was applied daily to the hotspot of the lesional hemisphere. The SCI patients in the control group underwent sham rTMS and conventional rehabilitation therapy. The participants in both the groups received therapy five days per week for six weeks. Latency, amplitude, and velocity were assessed before and after the six-week therapy period. A significant difference in post-treatment gains for the latency and velocity was observed between the experimental and control groups (p < 0.05). However, no significant differences in the amplitude were observed between the two groups (p > 0.05). The results of this study indicate that rTMS may be beneficial in improving motor recovery in the lower extremities of subacute stage SCI patients.

• 대한임상검사과학회지
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• 제39권2호
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• pp.136-140
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• 2007

The aim of this study was to examine the effect of differences in age and sex on vestibular evoked myogenic potentials (VEMP), particularly in normal participants. Briefly, the VEMP is a response elicited by loud clicks or tone bursts recorded from the tonically contracted sternocleidomastoid muscle. A total of 72 participants were divided into 6 groups according to their age and sex (20~30/F, 20~30/M, 40~50/F, 40~50/M, ${\geq}60/F$, ${\geq}60/M$). We got the data of latency, amplitude, and asymmetry index of the amplitude(ASI) from them. As a result of this study, there are variations in VEMP amplitudes and ASI depending on the muscle tension and the intensity of stimuli. In contrast, the latency of the response is usually less varied and does not differ significantly.

• 한국심리학회지:법
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• 제12권2호
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• pp.151-169
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• 2021

P300 숨긴정보검사에서 거짓말 여부를 판단하기 위하여 가장 많이 사용되는 기법은 부트스트랩 진폭차이(BAD) 방법과 부트스트랩 상관차이(BCD) 방법이다. 두 방법의 정확판단율을 비교한 선행연구들은 일관되지 않은 결과를 보고하였다. 일부의 연구들에서 BAD 방법이 BCD 방법보다 더 정확하다고 보고되고 있지만, 다른 연구에서는 BCD 방법이 BAD 방법보다 더 정확한 것으로 나타났다. 본 연구의 목적은 BAD 방법의 정확도가 더 높은 조건과 BCD 방법의 정확도가 더 높은 조건을 확인하는 것이다. 몬테 카를로 연구결과, 전반적으로 BAD 방법의 오경보율이 BCD 방법의 오경보율보다 더 높았으며, BAD 방법의 적중률이 BCD 방법의 적중률보다 더 높았다. 관련자극과 무관련자극의 P300 잠재시간이 비슷한 경우에 비교하여 관련자극의 P300 잠재시간이 약 100ms 빠른 경우에는 BCD 방법의 적중률이 크게 감소하였으며, 약 100ms 느린 경우에는 BCD 방법의 적중률이 증가하였다. 관련자극의 P300 진폭이 무관련자극의 P300 진폭보다 약간 더 크면서 관련자극의 P300 잠재시간이 목표자극의 P300 잠재시간보다 긴 경우에는 BCD 방법의 적중률이 BAD 방법의 적중률보다 더 높았다. BAD 방법의 오경보율이 높은 이유와 BCD 방법의 적중률이 관련자극의 P300 잠재시간에 영향을 받는 이유에 대해서 논의하였다.

• 대한임상전기생리학회지
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• 제2권3호
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• pp.37-49
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• 2004

The purpose of this study was to determine the effect of spinal motor neuron excitability by cranial electrostimulation(CES). The fifteen Sparague-Dawley adult male rats were assigned to the three groups; GroupI(control), GroupII(low rate CES), GroupIII(high rate CES). Spinal motor neuron excitability was measured to use a computerized H reflex. The results of this study was as follows; M latency, M amplitude and H latency were no significant difference in all groups on repeated measured ANOVA(p>.05) but low rate CES and high rate CES groups were lower than ether group in comparative measurement of H amplitude and Hmax/Mmax ratio(p<.05). These results lead to the conclusion that spinal neuron excitability was influenced by CES. These results suggest that CES had the capability to lower spinal motor neuron excitability used synaptic blockade in spinal segment.

• Korean Journal of Acupuncture
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• 제23권4호
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• pp.135-145
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• 2006

Objectives and Methods : Using the 2-channel DROS SQUID (Korea Research Institute of Standards of Science, 1999), the present study was carried out to record changes elicited in the auditory cortex by acupuncture stimulus on right TE5 (Waiguan) and GB43 (Xiaxi). Needle-retention stimulation of TE5 and GB43 were done for acquiring the brain activities changed by acupuncture. Acupoint TE5 and GB43 is known to be effective for the treatment of ear-related disease, such as deafness and tinnitus, and to be suspected to be related to the auditory cortex. Auditory evoked magnetic fields were recorded hem the left hemisphere of five subjects, in response to contralateral ear stimulation by irregularly spaced 170 msec long 1kHz tone busts (Korea Research Institute of Standards of Science) Results and Conclusions : The result as follows. The latency and amplitude of SQUID MEG responses at the human auditory cortex changed by needle-retention condition on TE5 were 4msec and 9.2 fT, respectively, which were slower and smaller than those of no-acupuncture condition. The latency and amplitude of SQUID MEG responses at the human auditory cortex changed by needle-retention condition on GB43 were 7.2 msec and 1.6 fT, respectively, which were slower and larger than those of no-acupuncture condition. The latency of SQUID MEG responses at the human auditory cortex changed by needle-retention condition on GB43 condition was slower than that of TE5 acupuncture condition.