• Journal of Biomedical Engineering Research
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• v.21 no.5
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• pp.477-485
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• 2000

본 논문에서는 신경신호기록을 위한 반도체 미세전극용 전치증폭기의 잡음특성을 설계하기 위한 체계적인 방법을 제시한다. 세포외기록(extracellular recording)에 의하여 측정된 신경신호와 전형적인 CMOS소자의 저주파 잡음특성을 함계 고려하여 전체 신호대잡음비를 계산하였다. 2단 CMOS 차동증폭기에 대한 해석과 함께 신호대잡음비에 중요한 영향을 끼치는 요소들에 대하여 설명하였다. 출력잡음전력에 대한 해석적인식을 유도하였으며 이로부터 회로설계자가 조절할 수 있는 주파수응답과 소자 파라미터들을 결정하였다. 입력소자의 크기와 트랜스컨덕턴스의 비가 최적영역으로부터 약간 벗어날 경우에 신호대잡음비가 크게 저하됨을 보였다. 이와 함께 만족스런 잡음특성을 위한 증폭이의 설계 변수 값들도 제시하였다.

• The Korean Journal of Physiology and Pharmacology
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• v.10 no.6
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• pp.303-307
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• 2006

The effects of ethanol on corticostriatal synaptic transmission were examined, using extracellular recording and analysis of population spike amplitudes in rat brain slices, to study how acute ethanol intoxication impairs striatal function. Ethanol caused a decrease in population spike amplitudes in a dose dependent manner ($50{\sim}200mM$). Pretreatment with picrotoxin, a ${\gamma}-amino$ butyric acid $(GABA)_{A}$ receptor antagonist, increased the population spikes but ethanol (100 mM) was still effective in decreasing the population spikes under this condition. In the presence of $_{(DL)}-2-amino-5-phosphonovaleric$ acid (APV), N-methyl-D-aspartate (NMDA) receptor antagonist, the inhibitory action of ethanol on population spikes was not shown. These results suggest that ethanol inhibits the glutamatergic corticostriatal synaptic transmission through blockade of NMDA receptors.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.4
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• pp.193-197
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• 2002

In spite of abundant anatomical evidences for the fiber connection between vestibular nuclei and inferior olivary (IO) complex, the transmission of vestibular information through the vestibulo- olivo-cerebellar climbing fiber pathway has not been physiologically established. The aims of the present study were to investigate whether there are IO neurons specifically responding to horizontal rotation and also in which subregions of IO complex these vestibularly-activated neurons are located. The extracellular recording was made in 68 IO neurons and responses of 46 vestibularly-activated cells were analyzed. Most of the vestibularly-activated IO neurons responded to signals of vertical rotation (roll), while a small number (13/46) of recorded cells were activated by horizontal canal signal (yaw). Regardless of yaw-sensitive or roll-sensitive, vestibular IO neurons were excited, when the animal was rotated to the side contralateral to the recording side. The gain and excitation phase were very similar to otolithic or vertical-canal responses. Histologic identification of recording sites showed that most of vestibular IO neurons were located in ${\beta}$ subnucleus. Electrical stimulation of a HSC evoked an inhibitory effect on the excitability of the ipsilateral IO neurons. These results suggest that IO neurons mainly in the ${\beta}$ subnucleus receive vestibular signals from semicircular canals and otolithic organs, encode them, and transmit vestibular information to the cerebellum.

• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.857-859
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• 2000

A planar MEA(Multi-channel Electrode Array) has been developed for monitoring the electrical activity of electrogenic cells in a cell culture by an extracellular recording. The material, fabrication process, characterization of the array, cleaning effect and impedance according to opening size by impedance measurement are described.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.9
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• pp.423-430
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• 2002

The fabrication and experimentation of multi-channel electrodes which enable detecting and recording of multi-site neuronal signals have been investigated. A multi-channel electrode array was fabricated by depositing 2000${\AA}$ thick Au layer on the 1000${\AA}$ thick Ti adhesion layer on a glass wafer. The metal paths were patterned by wet etching and passivated by depositing a PECVD silicon nitride insulation layer to prevent signals from intermixing or cross-talking. After placing a thin slice of rat cerebellar granule cell in the culture ring located in central portion of the multi-channel electrode plate, a neuronal signal from an electrode which is in contact with the cerebellar granule cell has been detected. It was found that the electrode impedance ranges 200㏀∼1㏁ and the impedance is not changed by cleaning with nitric acid. Also, the impedance is inversely proportion to the exposed electrode area and the cross-talk is negligible when the electrode spacing is bigger than 600$\mu\textrm{m}$. The amplitude and frequency of the measured action potential were 38㎷ and 2㎑, which are typical values. From the experimental results, the fabricated multi-channel electrode array proved to be suitable for multi-site neuronal signal detection for the analysis of a complicated cell network.

• Journal of Korean Society on Water Environment
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• v.39 no.3
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• pp.223-230
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• 2023

Harmful algae blooms have become a serious environmental problem in major river basins in Korea. They are known to produce various algal organic matters (AOMs) including intracellular organic matters (IOMs) and extracellular organic matters (EOMs). Generally AOMs cannot be easily removed by coagulation/flocculation process in conventional drinking water plants. AOMs produced by blue-green algae also include various toxins such as Microcystins, Anatoxin-a, and Saxitoxin known to have harmful effects on living organisms in aquatic environment. In this study, toxic effects of EOMs produced by three different algae species (Microcystis sp., Anabaena sp., and Oscillatoria sp.) on zebrafish were investigated using electroencephalography (EEG) recording method, a technology for recording brain activity. Electroencephalographic changes in zebrafish revealed that a low EOM had a negative effect on zebrafish compared to both Anabaena sp. and Oscillatoria sp. at 30 ppm EOM exposures. This result might be due to Microcystins present in EOMs produced by Microcystis sp. As a result of power spectrum density anallysis, exposure to EOMs produced by Microcystis sp. caused a state of vigilance in zebrafish. This EEG based toxicity test can be used to examine effects of harmful materials at low levels on living organisms in an aquatic system.

• The Korean Journal of Physiology
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• v.28 no.2
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• pp.151-157
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• 1994

Intracellular free $Ca^{2+}$ contributes to regulation of various events occurring in vascular smooth muscle cells. One of these events is modulating the membrane iou currents. Single smooth muscle cells were isolated from rabbit mesenteric artery. Three kinds of $Ca^{2+}-activated\;current$ were studied with the patch clamp method. $Ca^{2+}-activated\;K^+\;current$ with a large oscillation was recorded in the depolarized potential range. The single channel conductance of this current was about 250 pS. It was abolished by replacing intracellular $K^+\;with\;Cs^+$. A $Ca^{2+}-activated$ nonselective cation current was observed in both the depolarized and hyperpolarized potential ranges. And it was blocked by replacement of extracellular $Na^+$ with N-methylglucamine (NMG) or extracellular application of $Cd^{2+}$. $Ca^{2+}-activated\;Cl^-\;current$ was revealed in the whole voltage range and was blocked by niflumic acid. These results indicate that at least three kinds of $Ca^{2+}-activated$ ionic currents exist in smooth muscle cells from rabbit superior mesenteric artery.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.6
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• pp.1463-1467
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• 2003

In the present study, the effects of Ginseng radix and Ophiopogonis tuber on field potentials in rat hippocampal slices and cardiac muscle slices were investigated by multi-channel extracellular recording using MED64 system. The field potentials in the brain slices represent synaptic transmission and nerve excitability, and the field potentials in heart muscles represent muscle contractility. The present results show that the aqueous extract of Ginseng radix enhanced field potentials in the both hippocampal slices and cardiac muscle slices. In contrast, the aqueous extract Ophiopogonis tuber exerted no significant effect on the field potentials in the hippocampal slices and cardiac muscle slices. These results suggest the possibility that Yin-Yang theory could be studied in relation with excitability in neurons and muscles.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.24-28
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• 2007

Presuming that firing neurons have motions inside the MRI magnet due to the interaction between the neuronal magnetic field and the main magnetic field, we applied motion encoding gradients to dissected snail ganglia to observe faster responding MRI signal than the BOLD signal. To activate the snail ganglia in synchronization with the MRI pulse sequence, we used electrical stimulation with the frequency of 30 Hz and the pulse width of 2s. To observe the fast responding signal, we used the volume selected MRI sequence. The magnetic resonance signal intensity, measured with 8 ms long motion encoding gradient with a 20mT/m gradient strength, decreased about $3.46{\pm}1.48%$ when the ganglia were activated by the electrical stimulation.

• Korean Journal of Exercise Nutrition
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• v.13 no.1
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• pp.15-21
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• 2009

Ergogenic aids are substances, devices, and practices that enhance an individual's energy use and production, and recovery from fatigue. L-carnitine increases enhance performance and aerobic capacity by stimulating lipid oxidation in muscle cells during long term exercise. L-carnitine is a well known and widely used ergogenic aid. In the present study, the effect of L-carnitine at concentrations of 100 nM, 1 μM, 10 μM, and 100 μM on the amplitude of field potential in rat cardiac muscle slices was measured using multi-channel extracellular recording (MED 64) system. In the present result, L-carnitine was shown to enhance field potential as a does-dependent manner. The increasing effect of the L-carnitine on field potential was not affected by application of the glibenclamide, an ATP-dependant K⁺ channel antagonist. The increasing effect of L-carnitine on field potential was suppressed by application of the diazoxide, an ATP-dependent K⁺ channel agonist. Present data show that L-carnitine potentiates field potentials by inhibition on ATP-dependant K⁺ channel in cardiac muscles. The enhancing effect of the L-carnitine on the field potential in cardiac muscles can be suggested as one of the underlying mechanism of ergogenic aid of the L-carnitine.