• 대한의용생체공학회:의공학회지
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• 제38권1호
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• pp.16-24
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• 2017

For the development of feasible retinal prosthesis, one of the important elements is acquiring proper judging tool if electrical stimulus leads to patient's visual perception. If evoked potential to electrical stimulus is recorded in primary visual (V1) cortex, it means that the stimulus effectively evokes visual perception. Therefore, in this study, we established VEP recording system on V1 cortex using BioPAC modules as the judging tool. And the measuring system was evaluated by recording VEP of mice. After anesthesia, normal mice (C57BL/6J strain; n = 6) were secured to stereotaxic apparatus (Harvard Apparatus, USA). For the recording of VEP, the stainless steel needle electrode (impedance: $2-5k{\Omega}$) was positioned on the surface of the cortex through the burr hole at 2.5 mm lateral and 4.6 mm caudal to bregma. DA 100C and EEG 100C BioPAC modules were used for the trigger signal and VEP recording, respectively. When left eye was blocked by black cover and right eye was stimulated by flash light using HMsERG (RetVet Corp, USA), VEP response at left V1 cortex was detected, but there was no response at right V1 cortex. Amplitudes and latencies of P2, N3 peaks of VEP recording varied according to the depths of the electrodes on V1 cortex. From the surface upto $600{\mu}m$ depth, amplitudes of P2 and N3 increased, while deeper than $600{\mu}m$, those amplitudes decreased. The deeper the insertion depth of the electrode, the latency of N1 peaks tends to be delayed. However, there was no statistically significant difference among the latencies of P2 and N3 peaks (P > 0.05, ANOVA). Our VEP recording data such as the insertion depth and the latency and amplitudes of peaks might be used as guidelines for electrically-evoked potential (EEP) recording experiment in near future.

• The Korean Journal of Physiology and Pharmacology
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• 제19권2호
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• pp.167-175
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• 2015

A retinal prosthesis is being developed for the restoration of vision in patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Determining optimal electrical stimulation parameters for the prosthesis is one of the most important elements for the development of a viable retinal prosthesis. Here, we investigated the effects of different charge-balanced biphasic pulses with regard to their effectiveness in evoking retinal ganglion cell (RGC) responses. Retinal degeneration (rd1) mice were used (n=17). From the ex-vivo retinal preparation, retinal patches were placed ganglion cell layer down onto an $8{\times}8$ multielectrode array (MEA) and RGC responses were recorded while applying electrical stimuli. For asymmetric pulses, 1st phase of the pulse is the same with symmetric pulse but the amplitude of 2nd phase of the pulse is less than $10{\mu}A$ and charge balanced condition is satisfied by lengthening the duration of the pulse. For intensities (or duration) modulation, duration (or amplitude) of the pulse was fixed to $500{\mu}s$($30{\mu}A$), changing the intensities (or duration) from 2 to $60{\mu}A$(60 to $1000{\mu}s$). RGCs were classified as response-positive when PSTH showed multiple (3~4) peaks within 400 ms post stimulus and the number of spikes was at least 30% more than that for the immediate pre-stimulus 400 ms period. RGC responses were well modulated both with anodic and cathodic phase-1st biphasic pulses. Cathodic phase-1st pulses produced significantly better modulation of RGC activity than anodic phase-1st pulses regardless of symmetry of the pulse.

• 대한임상검사과학회지
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• 제45권4호
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• pp.170-179
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• 2013

There is a correct way to avoid any sequale in the central motor area during neurosurgery procedures. A clear way to find the circumference of the central sulcus, central motor, and sensory areas by giving cortical electrical stimulation to the central motor area immediate after surgery is proposed. Looking at patients who underwent brain surgery September 2009 to July 2013, the central sulcus and speech areas around the central area of the brain was investigated, using the practices of either a localized brain map check or a direct cortical electrical stimulation test. Brain maps localized around the surgical site through functional movement or speech areas were identified. Accurate tests done during surgery without damage to motor neurons or after surgery were conducted smoothly. Although successful brain map test localization can be accomplished, there are some factors that can interfere. The following phenomena can reverse the phase: (1) the first sensory / motor in the case of patients severe nerve damage; (2) placement of the electrode on top of the vessel; (3) presence of a brain tumor near the brain cortex; (4) use of anesthesia if patient cooperation is difficult; and (5) location of the electrode position and stimulus is inappropriate.

• 대한의용생체공학회:의공학회지
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• 제36권5호
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• pp.221-227
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• 2015

In this study, Multi-Array Electrodes (MAE) and Programmable Multi-channel Electrical Stimulator (PMES) were implemented for firing Trigger Points (TPs) of the patient with Myofascial Pain Syndrome (MPS). MAE has 25 Ag/AgCl electrodes arranged in the form of array ($5{\times}5$) fabricated with flexible pad, which are applicable to be easy-attached to curved specific region of the human body. PMES consisted of 25 channels. Each channel was to generate various electric stimulus patterns (ESPs) by changing the mono-phasic or bi-phasic of ESP, On/Off duration of ESP, the interval between ESP, and amplitude of ESP. PMES hardware was composed of Host PC, Stimulation Pattern Editing Program (SPEP), and Multi-channel Electrical Stimulator (MES). Experiments were performed using MAE and PMES as the following. First experiment was performed to evaluate the function for each channel of Sub- Micro Controller Unit (SMCU) in MES. Second experiment was conducted on whether ESP applied from each channel of SMCU in PMES was focused to the electrode set to the ground, after applying ESP being output from each channel of SMCU in PMES to MAE.

• Restorative Dentistry and Endodontics
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• 제16권2호
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• pp.85-98
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• 1991

The aim of this study was to investigate the effect of low - power laser used in the medical field for various purposes to suppress pain responses evoked by noxious electrical or mechanical stimuli. After both inferior alveolar nerves and the left anterior digastric muscle of cats under general anesthesia were exposed, a recording electrode for the jaw opening reflex was inserted into the anterior digastric muscle. The right inferior alveolar nerve was dissected under a surgical microscope until the response of the functional single nerve could be evoked by the electrical stimulation of the dental pulp or oral mucosa. The electrical stimulus was applied with a rectangular pulse of 10 ms duration for measuring the threshold intensity of a single nerve fiber in the inferior alveolar nerve which responds to stimulation of dental pulp and oral mucosa. Then a pulse of 1 ms duration was applied for determination of conduction velocity. A noxious mechanical stimulus to the oral mucosa was applied by clamping the receptive field with an arterial clamp. The Ga-As diodide laser(wave length, 904 nm ; frequency, 1,000 Hz) was irradiated to the prepared tooth cavity, inferior alveolar nerve and oral mucosa as a pulse wave of 2 mW for 6 minutes. This was followed by a continuous wave of 15 mW for 3 minutes. The action potential of the nerve and EMG of the digastric muscle evoked by the noxious electrical stimulus and nerve response to noxious mechanical stimulus were compared at intervals of before, immediately after, and at 5, 10, 20, 40, 60 minutes after laser irradiation. The results were as follows: The conduction velocity of the intrapulpal $A{\delta}$- nerve fiber recorded from the inferior alveolar nerve before irradiation had a mean value of $6.68{\pm}2.07m/sec$. The laser irradiation did not affect the conduction velocity of the AS - nerve fiber and did not change the threshold intensity or amplitude of the action potential either. The EMG of the digastric muscle evoked by noxious electrical stimulation to the tooth was not changed by the laser irradiation, whether in latency, threshold intensity or amplitude. The laser irradiated to the receptive field of the oral mucosa which was subjected to noxious stimuli did not affect the amplitude of the action potential or the frequency either.

• 대한의용생체공학회:의공학회지
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• 제20권2호
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• pp.183-190
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• 1999

본 논문은 족하수 환자를 대강으로 휴대가 간편하고 사용이 편리한 피드백 제어형 전기자극기를 제안하는 데 그 목적이 있다. 이 시스템은 교통사고, 산업재해, 뇌졸중 등으로 인하여 하지마비를 동반한 환자에서 마비된 하지근의 위축 및 괴사를 방지하고 혈액순환을 증가시킬 뿐만아니라 보행을 보조하여 안정된 활동을 가능케 한다 피드백 제어형 전기자극기는 환자가 오랜 시간 보행시 전극의 임피던스 변화나 근피로에 의해 족하수증이 다시 발생하게 되면 관절각의 변화가 관절각 센서에 의해 검출되고 이때의 오차는 PID 제어에 의한 자극전압의 변화를 가져와 설정된 위치에 발목이 도달하도륵 자극레벨이 자동 조절된다. 자극조건은 자극주파수 40 Hz, 자극펄스 0.2 ms, 30∼80 V이다. 족하수 환자 5명을 대상으로 42일 동안 첫째 1주일 동안에는 하루에 15분을 자극하고, 다음 주기는 1주일 단위로 하루에 30분, 60분, 70분, 120분씩 점차적으로 시간을 증가하면서 자극하였다. 이때 근력은 27.7%가 향상되었고, 근 피로도는 22.9%가 감소되었다. 이런 결과를 종합할 때 피드백 제어형 전기자극기는 족하수 환자의 보행기능 및 운동기능을 회복하는 데 효과적이라 하겠다.

• 대한의용생체공학회:의공학회지
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• 제22권6호
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• pp.487-496
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• 2001

본 연구에서는 PIC(마이크로 컨트롤러)를 이용하여 전정계 기능 검사를 할 수 있도록 앙극 (bipolar) 자극이 가능한 정전류 자극기를 제작하였다. 정전류원이 구동할 수 있는 최대 부하와 최대 전류는 각각 3$k\Omega$. 5mA로 하였다. 그리고 자극 패턴은 직류. 정현파, 혹은 펄스파가 가능하도록 제작하였다. 정상인 20명을 대상으로 전기 자극 방법에 따른 안구 운동을 영상 안구운동 검사기(videooculograph; VOG)를 이용하여 분석하였다. 자극 패턴은 직류. 자극 시간은 30초로 하여. 전류의 세기에 대한 안진 반응을 살펴보기 위해 각 피검자마다 자극 전류가 0.75. 1, 2. 3mA인 경우에 대하여 실험하였다 자극 전류의 세기가 2mA 이상일 때는 검사 대상자 모두에게서 안진이 발생하였다 전류의 세기를 0.75에서 3mA로 증가시켰을 때. 느린 성분의 안구운동 속도의 평균은 1.1에서 4.8 deg/sec로 증가하였고. 안진의 평균 횟수 또한 17회에서 48회로 증가하였다. 전기 자극으로 인한 빠른 성분의 안구운동은 일관되게 음 자극을 가하는 전극이 있는 방향으로 나타났으며 좌우 반응의 타이를 나타내는 비대칭도는 전류가 증가할수록 감소하였다. 본 연구는 전기 자극을 이용한 전정 기능 평가와 전정 안반사의 생리기전 연구의 기초 자료로 활용할 수 있을 것으로 사료된다.

• 전기학회논문지
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• 제63권7호
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• pp.968-975
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• 2014

This paper proposed a evaluation method for individual's subjective preferred location using EEG and emotional assessment. Visual stimulus were sequentially presented a total six points(the top and the bottom of the left, the top and the bottom of the center and the top and the bottom of the right on the screen). EEG were measured from twenty subjects according to each six points. At the same time, we were executed evaluation of subjects preferred location from emotional assessment. Alpha and beta wave were measured in Fp1, Fp2, F7 and F8 location, followed by ten to twenty electrode system. Correlations and variations of alpha and beta wave from each channel were calculated and analyzed. Because of the number of subjects population under 30, we used Speareman test for a correlation analysis between alpha and beta wave. Also, emotional assessments which compose of visual sense harmony, visual sense stability, stability of position and the visibility were performed and were analyzed by average and frequency. After visual stimulus, emotional assessments were performed. From the variance analysis of EEG, beta wave from F7 was appeared statistically significant as significance probability of 0.006. Also, between alpha wave and beta wave appeared a negative correlation(r=-0.190). From the post-hoc test of F7 beta wave, location 1, 5 and 6 appeared to difference statistically significant. Emotional assessment result according to six positions showed 0.00 significance probability. Thus, location and emotional assessment appeared to influence on each other. From the average and frequency analysis of emotional assessment, location 2 showed obtained of best emotional assessment score and appeared lower beta wave than other locations. Finally, most subjects showed a preference for location 2. Through obtained results in this paper, will be helpful to about human emotional assessment and EEG research.

• 대한소아치과학회지
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• 제27권1호
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• pp.7-14
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• 2000

가바성 억제 신경세포는 해마의 정상적인 기능을 조절하는데 중요한 역할을 하며 해마 병변을 유발하는 중요한 요소이다. 본 연구는 in vivo 실험법을 사용하여 해마 CA1 영역에서의 전기 생리학적 반응을 측정함으로써 가바성 신경세포의 기능을 분석하고 이를 슬라이스 실험법과 비교하고자 하였다. Fimbria-fonix 전기자극시 전형적인 population spike가 나타났고 $10{\sim}M$ bicuculline 존재하에서는 전기자극에 의해 burst 형태의 population spike가 나타났다. Population spike의 크기는 자극 강도에 비례하였으며 그 숫자도 bicuculline 전극사용시와 같이 동일한 양상을 보였다. CA1 영역의 흥분성 수준을 측정하기 위해 paired-pulse 자극을 하였는데 짧은 자극 간격에서 억제성 반응을 보였고 burst형태의 afterdischarge를 나타내었다. CA1 영역에서 in vivo실험법을 사용한 가바성 신경세포반응의 결과는 추체세포의 흥분성 조절을 효과적으로 분석할 수 있으며 in vitro 실험법에 비해 기능적 평가가 더욱 이상적임을 알 수 있다.

• 대한의용생체공학회:의공학회지
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• 제25권2호
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• pp.151-156
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• 2004

편마비 환자에서 상지 기능을 효과적으로 회복시키기 위하여 근전도 유발 기능적 전기자극기 개발과 편마비 환자를 대상으로 손목, 수지신전 운동 시 가장 효과적으로 근수축을 감지 할 수 있는 위치와 전기 자극 시 가장 이상적인 손목, 수지 신전 운동이 일어나는 부위를 탐색하여 두 부과가 일치하는 이상적인 전극부착 위치를 설정하였다. 1) 전기자극 시스템으로 EMC 계측부, 정전류 회로부를 개발하고 프로그램으로는 근전도 유발 전기자극기와 Passive FES의 동작이 가능한 형태로 개발하였다 자극조건은 주파수 35 Hz, 펄스폭 150 ${\mu}\textrm{s}$, 비대칭적 이상성 파형을 선택하였다. 2) 상지 편마비 환자 15명을 대상으로 전완의 근위부 1/2부위를 12개의 영역으로 나눈 후 근위부의 외측으로부터 영역의 순서를 정하였다. 각 영역에서 환자의 손목을 신전 하였을 때 근전도 유발 자극기가 감지하는 활동전위의 진폭을 측정하였으며 가장 크게 감지된 영역은 4, 5 영역이었고, 전기자극을 시행하였을 때 손목과 수지부위가 신전 되는 모양이 이상적인 영역은 4, 5, 7, 8 영역이었다. 근전도 유발 전기자극을 시행하였을 때 근 수축을 감지하여 근전도 유발 전기자극이 일어나는 일련의 과정이 이상적인 영역은 해부학적으로 4, 5 영역이었다.