Focused ultrasound-induced blood-brain barrier opening improves adult hippocampal neurogenesis and cognitive function in a cholinergic degeneration dementia rat model

BACKGROUND: The persistence of adult hippocampal neurogenesis (AHN) is sharply decreased in Alzheimer's disease (AD). The neuropathologies of AD include the presence of amyloid-β deposition in plaques, tau hyperphosphorylation in neurofibrillary tangles, and cholinergic system degeneration. The focused ultrasound (FUS)-mediated blood-brain barrier opening modulates tau hyperphosphorylation, the accumulation of amyloid-β proteins, and increases in AHN. However, it remains unclear whether FUS can modulate AHN in cholinergic-deficient conditions. In this study, we investigated the effect of FUS on AHN in a cholinergic degeneration rat model of dementia. METHODS: Adult male Sprague-Dawley rats (n = 48; 200-250 g) were divided into control (phosphate-buffered saline injection), 192 IgG-saporin (SAP), and SAP+FUS groups; in the two latter groups, SAP was injected bilaterally into the lateral ventricle. We applied FUS to the bilateral hippocampus with microbubbles. Immunohistochemistry, enzyme-linked immunosorbent assay, immunoblotting, 5-bromo-2'-deoxyuridine labeling, an acetylcholinesterase assay, and the Morris water maze test were performed to assess choline acetyltransferase, acetylcholinesterase activity, brain-derived neurotrophic factor expression, neural proliferation, and spatial memory, respectively. Statistical significance of differences in between groups was calculated using one-way and two-way analyses of variance followed by Tukey's multiple comparison test to determine the individual and interactive effects of FUS on immunochemistry and behavioral analysis. P < 0.05 was considered significant. RESULTS: Cholinergic degeneration in rats significantly decreased the number of choline acetyltransferase neurons (P < 0.05) in the basal forebrain, as well as AHN and spatial memory function. Rats that underwent FUS-mediated brain-blood barrier opening exhibited significant increases in brain-derived neurotrophic factor (BDNF; P < 0.05), early growth response protein 1 (EGR1) (P < 0.01), AHN (P < 0.01), and acetylcholinesterase activity in the frontal cortex (P < 0.05) and hippocampus (P < 0.01) and crossing over (P < 0.01) the platform in the Morris water maze relative to the SAP group after sonication. CONCLUSIONS: FUS treatment increased AHN and improved spatial memory. This improvement was mediated by increased hippocampal BDNF and EGR1. FUS treatment may also restore AHN and protect against neurodegeneration, providing a potentially powerful therapeutic strategy for AD.ope

Manipulation of Rat Movement via Nigrostriatal Stimulation Controlled by Human Visually Evoked Potentials

Here, we report that the development of a brain-to-brain interface (BBI) system that enables a human user to manipulate rat movement without any previous training. In our model, the remotely-guided rats (known as ratbots) successfully navigated a T-maze via contralateral turning behaviour induced by electrical stimulation of the nigrostriatal (NS) pathway by a brain- computer interface (BCI) based on the human controller's steady-state visually evoked potentials (SSVEPs). The system allowed human participants to manipulate rat movement with an average success rate of 82.2% and at an average rat speed of approximately 1.9 m/min. The ratbots had no directional preference, showing average success rates of 81.1% and 83.3% for the left- and right-turning task, respectively. This is the first study to demonstrate the use of NS stimulation for developing a highly stable ratbot that does not require previous training, and is the first instance of a training-free BBI for rat navigation. The results of this study will facilitate the development of borderless communication between human and untrained animals, which could not only improve the understanding of animals in humans, but also allow untrained animals to more effectively provide humans with information obtained with their superior perception.ope

A Fully Implantable Miniaturized Liquid Crystal Polymer (LCP)-Based Spinal Cord Stimulator for Pain Control

Spinal cord stimulation is a therapy to treat the severe neuropathic pain by suppressing the pain signal via electrical stimulation of the spinal cord. The conventional metal packaged and battery-operated implantable pulse generator (IPG) produces electrical pulses to stimulate the spinal cord. Despite its stable operation after implantation, the implantation site is limited due to its bulky size and heavy weight. Wireless communications including wireless power charging is also restricted, which is mainly attributed to the electromagnetic shielding of the metal package. To overcome these limitations, here, we developed a fully implantable miniaturized spinal cord stimulator based on a biocompatible liquid crystal polymer (LCP). The fabrication of electrode arrays in the LCP substrate and monolithically encapsulating the circuitries using LCP packaging reduces the weight (0.4 g) and the size (the width, length, and thickness are 25.3, 9.3, and 1.9 mm, respectively). An inductive link was utilized to wirelessly transfer the power and the data to implanted circuitries to generate the stimulus pulse. Prior to implantation of the device, operation of the pulse generator was evaluated, and characteristics of stimulation electrode such as an electrochemical impedance spectroscopy (EIS) were measured. The LCP-based spinal cord stimulator was implanted into the spared nerve injury rat model. The degree of pain suppression upon spinal cord stimulation was assessed via the Von Frey test where the mechanical stimulation threshold was evaluated by monitoring the paw withdrawal responses. With no spinal cord stimulation, the mechanical stimulation threshold was observed as 1.47 ± 0.623 g, whereas the stimulation threshold was increased to 12.7 ± 4.00 g after spinal cord stimulation, confirming the efficacy of pain suppression via electrical stimulation of the spinal cord. This LCP-based spinal cord stimulator opens new avenues for the development of a miniaturized but still effective spinal cord stimulator.ope

연령·건강·독거 효과를 중심으로

본 연구의 목적은 장년 가구에서 노년 가구로 변화하면서 나타나는 연령 증가, 건강 악화, 독거 상황이 주거 소비행태에 미치는 영향을 분석하는 것이다. 연령 효과, 건강 효과, 독거 효과가 노년 가구의 주택 소비면적과 점유형태, 주거 이동과 노인 주택 선호에 미치는 영향은 다음과 같다. 첫째, 고령화 시대에 주택 시장은 소형 주택에 대한 수요가 증가할 것이다. 소득과 가구원 수를 통제한 상태에서도 연령 효과가 주택 소비면적에 영향을 미치고 있다. 즉 장년 가구에서 연령이 증가하여 노년 가구가 되면 주택 총 소비면적은 감소한다. 건강 효과와 독거 효과 또한 주택 소비면적에 영향을 미치고 있어 건강이 악화된 노년 부부와 독거노인의 주택 소비면적은 더욱 감소할 것으로 예상할 수 있다. 둘째, 고령화 시대에 주택 소비면적은 소득에 따라 양극화가 일어날 수 있다. 노년 가구가 되면 소득 변동이 커지고, 주택 면적에 대한 소득 탄력성이 증가하기 때문에 노년 가구의 주택 소비면적은 소득에 따라 양극화가 발생할 수 있다. 주택 소비면적의 양극화 현상은 건강한 노년 부부 가구에서 가장 심하게 나타나고, 건강이 악화되고, 독거하게 되면서 차츰 줄어들 것으로 예상할 수 있다. 셋째, 자가 노년 가구를 위해 소득 향상과 자발적인 주거 이동을 지원하는 정책이 마련될 필요가 있다. 자가로 점유하는 경우에 노년 가구는 장년 가구에 비해 소득 탄력성이 높다. 그러므로 자가 노년 가구의 주택 수요를 유지하기 위해서는 은퇴 후 재취업이 원활히 이루어지도록 하여 노년 가구의 소득을 높이는 것이 도움이 될 수 있다. 또한 자가 노년 가구의 건강이 악화되는 경우에 주택 면적이 감소하는 것이 반드시 주거 수준이 악화된 것을 의미하지 않는다. 자가 노년 가구가 주거 이동을 통해 가구의 상황에 맞게 주택 면적을 조정한 것일 수 있으므로 이러한 가구에게는 주거 이동을 위한 정보를 제공할 필요가 있다. 넷째, 건강이 악화된 노년 가구와 독거노인이 안정적으로 거주할 수 있도록 저렴한 임대주택을 충분히 공급할 필요가 있다. 장년 가구에서 노년 가구가 되면 자가 비율이 증가하지만 건강이 악화되거나 독거하게 되면 소득이 감소하고, 차가 비율이 증가한다. 그리고 차가 노년 가구는 자가 노년 가구에 비해 가격 탄력성이 높고, 주거 이동할 확률이 증가하기 때문이다. 다섯째, 고령화 시대에 주택 거래는 감소할 것으로 예상할 수 있다. 노년 가구는 장년 가구에 비해 거주기간이 길고, 연령 효과로 인해 주거 이동성이 낮아지기 때문이다. 하지만 차가 가구의 주거 이동은 증가하는 것으로 나타나 차가 노년 가구의 주거 불안정은 지속될 것이다. 여섯째, 고령화 시대에 의료 서비스 접근성은 더욱 중요해질 것이다. 주거 이동지역을 살펴보면 노년 가구가 비도시지역에서 도시지역으로 이동하기를 희망하는 비율이 높게 나타난다. 건강이 악화된 노년 가구는 의료 접근성을 개선하기 위해 주거 이동하기를 희망하는 경우가 많다. 또한 건강이 악화된 노년 가구는 노인 주택으로 이동하기보다는 현재 주택에 거주하기를 선호하고 있다. 그러므로 의료 서비스가 특화된 노인 주택을 공급하기보다는 노년 가구가 거주하는 지역의 의료 서비스 접근성을 개선하는 것이 노년 가구에게 더욱 도움이 될 수 있다. 일곱째, 노년 가구 특성을 반영하여 노인 주택을 공급할 필요가 있다. 많은 노년 가구가 노인 주택에 거주하기를 희망하고 있으나 노인 주택 공급량은 이에 미치지 못하는 것으로 나타난다. 향후 노년 가구의 수는 더욱 증가할 것으로 예상되므로 노인 주택을 공급할 필요가 있다. 하지만 노인 주택 수요의 대부분은 소규모 차가 수요이므로 이에 대한 고려가 필요하다. 노년 가구의 주거 소비행태 변화에 대한 분석이 주는 정책적 시사점은 다음과 같다. 첫째, 고령화가 진행되는 초기 단계에서는 노년 가구의 증가가 주택 시장에 미치는 영향이 크게 나타날 것으로 예상할 수 있다. 하지만 고령화가 지속됨에 따라 노년 가구의 건강 악화, 독거 상황이 주택 시장에 미치는 영향이 차츰 증가할 것으로 예상하며, 이에 따라 발생하는 주거 문제는 고령화 초기 단계와 다를 것으로 예상할 수 있다. 둘째, 노년 가구가 생애주기에서 겪게 되는 연령 증가, 건강 악화, 독거 상황이 주거 소비행태에 미치는 영향이 다르게 나타난다. 그러므로 고령화 시대의 주택 시장 변화를 정확히 예측하기 위해서는 노년 가구에서 나타나는 다양한 특성을 더욱 면밀히 파악할 필요가 있다. 셋째, 노년 가구의 점유형태에 따라 다른 정책이 필요할 것으로 예상할 수 있다. 자가 노년 가구를 위해서는 소득 향상과 주거 이동을 위한 정보 제공 등의 정책이 필요하며, 차가 노년 가구를 위해서는 재가복지서비스와 임대주택 공급 등의 정책이 필요하다. 하지만 이와 같은 연구의 결과와 시사점은 다음과 같은 한계가 있다. 첫째, 주택의 소비면적과 점유형태에 대한 분석 결과는 장년 가구가 노년 가구가 되는 시점에 선호가 변화할 수 있음을 고려하지 못하였다. 둘째, 주거 이동과 노인 주택 선호에 대한 분석 결과는 실제 노년 가구의 선택과 차이가 존재할 수 있으며, 장년 가구가 노년 가구와 다르게 노후를 인식함으로써 편의가 발생할 수 있다. 셋째, 노년 가구가 생애주기에서 겪는 변화 가운데 보편적으로 나타나는 연령 증가, 건강 악화, 독거가 순차적으로 발생한다고 가정함으로써 이와 다르게 생애주기 변화를 겪는 노년 가구의 주거 소비행태 변화를 고려하지 못한 한계가 있다.This study aims to analyze whether housing consumption behavior change during middle-aged households to elderly households was influenced by age increase, health deterioration and single household situation. Results showed that housing size, tenure type, and the preference for residential mobility and elderly housing were influenced by age effect, health effect and solitude effect. First, demand for small size housing may be increased in housing market in aged society. Under controlling household income and family size, age increase' affected housing size; when middle-aged household was aged, total housing consumption was decreased, and health deterioration and single household situation also affected housing size. Therefore, housing size may be more decreased, if elderly couples are unhealthy or if an elderly person lives alone. Second, housing consumption may be polarized by household income in aged society. The coefficient of variation of income and the income elasticity were higher in elderly households than middle-aged households. This polarization showed mostly in healthy aged couple: but may be diminished in unhealthy and solitary elderly household. Third, policy supporting income improvement and residential movement for elderly households is needed. For owners, the income elasticity was higher in elderly households than middle-aged households. If elderly households own housing, active re-employment system is recommended to keep their housing consumption. Also, if the elderly homeowners downsized their house due to their health problem, it did not always mean the decrease of housing quality. Rather, it means that that housing size may be adjusted by residential movement depending on household situation. Therefore, the information about residential relocation should be provided for old people. Fourth, for unhealthy elderly households and single senior citizen low-rent public housings should be sufficiently provided. The results showed that if households were aged, the owner occupancy rate was increased, but if old people were unhealthy or lived alone, household income decreased and renter occupancy rate increased. Also, the elderly tenants showed higher price elasticity of housing demand and residential mobility than elderly homeowners. Fifth, housing transaction may be decreased in aged society. Senior households were less likely to move the house than middle-aged households. However, the tenants had higher residential mobility than homeowners, which showed that their housing insecurity may be lasted. Sixth, in aged society the access to medical service may become more important. The results showed that aged households who were unhealthy tended to move to urban area enabling better medical service for their health care. Also, they preferred residing in present house to moving to the housing for the elderly. Thus, improving medical accessibility is more important than supplying the elderly housing which is specialized in medical service. Seventh, the supply of elderly housing should reflect the characteristics of elderly households. Many senior households hoped to live in elderly housing whereas the supply was insufficient. Furthermore, the number of elderly household is rapidly increasing. Thus, the supply of elderly housing needs to be increased. Also, the results showed that most senior households wanted to live in the low-rent elderly housing which was far smaller than their present housing size. These preference need to be considered in relation to supplying the elderly housing. The results in this study suggested policy implications for housing consumption behavior change of elderly households. First, at the beginning stage of aging society, the increase of aged household may have a strong impact on the housing market. However, the influence of health deterioration and single household situation among elderly people may grow gradually over time. Second, each effect of age increase, health deterioration, and solitude condition among elderly people influences on housing consumption behavior differently. Thus, for accurate prediction of the change of housing market in aged society, the characteristics of aged households need to be scrutinized. Third, different policy is needed by tenure type. For elderly homeowners, income improvement and the information about residential relocation are required, and for elderly tenants, domiciliary care service and low-rent public housing supply are needed. However, these results and suggestions should be considered in conjunction with following limitations. First, the result did not consider that housing consumption size and tenure type can be changed when middle-aged households become elderly households. Second, the results about elderly peoples stated preference for residential mobility and elderly housing may be different from their real choice. Moreover, these results may be biased because current middle-aged household may differently perceive their old ages from current senior households. Third, the three effects: age increase, health degeneration and solitude were assumed that they happened in order. Thus, the results did not consider senior households who experienced life cycle differently from those.Docto

A Case Study on Employment Extension and Wage Adjustment in Japanese Companies

우리나라는 2000년에 고령화 사회에 진입한 이후 2019년에는 고령사회, 2026년에는 초고령 사회에 도달할 것으로 전망되어 일본 등 선진국에서 경험한 것보다 인구 고령화가 훨씬 더 빠른 속도로진행되고 있다. 이와 같은 노동력의 고령화는 한국 기업의 특징인 연공급 임금체계와 맞물려 기업의인건비 부담을 가중시키는 중요한 요인으로 작용하게 된다. 일본의 경우, 1998년에 정년 60세를 의무화한 이후에도 2006년부터 2013년 4월까지 정년을 65세로 단계적으로 상향 조정해 왔는데, 기업들은 이에 대응하여 임금조정을 동반한 다양한 형태의 고용연장을 시행해 왔다. 일본기업의 고용연장은 기업내부 고용연장과 기업외부 고용연장 유형으로 구분할 수 있는데, 전자는 정년연장과 재고용으로, 후자는 출향(出向)과 고령자 다수고용기업 전적으로 구분된다. 이 밖에도 다양한 형태의 고령자 시간제고용 유형이 있다. 일본 기업들은 60세 이후 고용연장을 할 경우, 다양한 정년트랙을 두고 근로자에게 선택권을 부여하고 있다. 정년연장형의 경우에는 정년이후의 계속 고용기간에 따라 정년 이전부터 임금을 체계적으로 삭감하는 임금피크제 도입이 많으며, 재고용형의 경우에는 직무급 체계를 도입하거나, 성과급비중을 높이는 방법을 활용한다. 기존 정년 이후 승진․승급은 이루어지지 않는 것이 일반적이나 베이스 업(base-up)은 해 주는 경우가 많다. 근로자가 일단 정년퇴직을 한 후 새로운 회사에 출향(出向) 또는 전적을 하는 기업외부 고용연장이나 시간제 고용연장의 경우에는 업무 내용과 근로시간에 따라 성과급, 직무급, 계약급, 시간급 등 기존과는 전혀 다른 임금제도와 임금수준을 적용하고 있다. 우리나라의 경우에도 고령화 추세와 향후 인력부족, 그리고 국민연금 재정 악화 전망 등을 종합해볼 때 머지않은 장래에 60세를 초과하는 고용연장이 추진될 것으로 예견된다. 따라서 우리 기업들도중장기적 관점에서 이에 대한 대비가 필요하다. 일본기업의 고용연장과 임금조정 경험으로 부터 다음과 같은 시사점을 얻을 수 있다. 첫째, 우리나라도 일본과 같이 다양한 유형의 고용연장 방식을 검토하고 이를 도입할 필요가 있다. 둘째, 정년연장을 하더라도 선택정년제 도입과 근로자 선택권을 부여하는 것이 바람직하다. 셋째, 고용연장의 유형, 고령자의 업무내용, 근로시간 등에 따라 임금피크제 외에도 성과급이나 직무급, 계약급과 시간급 등 다양한 임금체계를 도입해야 한다.South Korea had passed an aging society in 2000 and will form an aged society in 2019. In 2026, Korea is expected to reach the status of super aging society, as the speed of aging of its population is more rapid than that of such advanced countries as Japan and the USA. The aging of the workforce will become an important factor, aggravating the burden of labor costs of Korean companies, alongside the seniority compensation system, which is one of the main characteristics of Korean companies. The Act on Age Discrimination Prohibition in Employment and Aged Employment Promotion was amended by the National Assembly in April 30, 2013, so that the retirement age will be extended to 60 in 2016. Concerns about the burden of labor costs of Korean companies are increasingly becoming reality. According to the Act, the issue of reforming the compensation system to conform to the extension of the retirement age is assigned to discussions between labor and management. Therefore, finding measures for reducing the burden of labor costs is becoming an urgent issue for companies. Accordingly, this paper aims to provide the policy alternatives for Korean companies to lessen the burden of labor costs, through an analysis of the experience of Japanese companies relative to employment extension. The types of employment extension of the older workers in Japanese companies can be categorized into two different types: full-time and part-time employment extension. It was discovered that the companies methods of wage adjustment were different according to the employment extension types. As for the companies which extended their retirement age, the peak wage system was mostly applied, and wages were decreased beginning a few years before the pre-existing retirement age. In the case of reemployment, a new contract wage system such as jobbased pay and performance-based pay was universally introduced. In the case of seconded employees, the wage differential between the original (loan) companies and the subsidiary (seconded) ones was mostly paid by the original ones. As for the companies which were established exclusively for older workers, in consideration of their pensions, wages were arranged to be more or less lower than the pay they had received before retirement. Part-time workers were generally paid at an hourly rate in proportion to their working hours. Through this case study of Japanese companies, the use of various measures for the wage adjustment of older workers is seen, according to the type of employment extension. Since the legal retirement age is scheduled to be extended to 60 in 2017, Korean companies also need to consider various wage adjustment methods, which include the peak wage system, job-based pay, performancebased pay, etc., depending on the nature of the employment extension of older workers.본 논문에 연구비를 지원해 준 서울대학교 노사관계연구소에 감사를 표합니다

Injecting NMDA and Ro 25-6981 in insular cortex induce neuroplastic changes and neuropathic pain-like behaviour

BACKGROUND: Neuropathic pain is associated with abnormal sensitivity of the central nervous system. Although the mechanism underlying the development of sensitization remains to be fully elucidated, recent studies have reported that neuroplastic changes in the pain circuitry may be involved in hypersensitivity associated with neuropathic pain. However, it is difficult to investigate such phenomena in existing animal pain model. Therefore, in this study, we developed a novel animal model - the circuit plasticity reconstruction (CPR) model - to mimic central sensitization associated with neuroplastic changes. METHOD: NMDA and Ro 25-6981 were injected into the right insular cortex of Sprague-Dawley rats, while electrical stimulation was delivered to the contralateral hind paw. Mechanical allodynia was tested by von Frey test with up-down method, and neuroplastic changes were confirmed by PSA-NCAM-positive immunostaining. RESULT: The mechanical withdrawal threshold of the left hind paw decreased beginning 1 day after CPR modelling and persisted until day 21 comparing to the modified CPR 1 (mod-CPR 1) group (CPR: 91.68 ± 1.8%, mod-CPR 1: 42.71 ± 3.4%, p < 0.001). In contrast, mod-CPR 2 surgery without electrical stimulation did not induce mechanical allodynia. Immunostaining for PSA-NCAM also revealed that neuroplastic changes had occurred in the CPR group. CONCLUSION: Our results demonstrated that CPR modelling induced neuroplasticity within the insular cortex, leading to alterations in the neural circuitry and central sensitization. SIGNIFICANCE: This article represents that the CPR model can mimic the neuropathic pain derived by neuroplastic changes. Our findings indicate that the CPR model may aid the development of novel therapeutic strategies for neuropathic pain and in elucidating the mechanisms underlying pain induced by central sensitization and neuroplastic changes.restrictio

Numerical study of microwave propagation in an electron cyclotron resonance waveguide coupler using finite element method with edge elements

학위논문(석사) - 한국과학기술원 : 전기 및 전자공학과, 1992, [ [ii], 56 p. ]한국과학기술원 : 전기 및 전자공학과

Development of wireless neural interface system

Purpose : Advances in experimental devices have led to substantial achievements in electrophysiological studies in the last few decades. However, conventional systems tend to hinder freely moving behavioral tests, because of the use of tethering cables connecting subjects to devices. To tackle this limitation, we developed a wireless neural interface system (WNIS) that is capable of multi-channel recording and stimulation with a wireless charging battery. Methods : The WNIS was fabricated in dimensions of 34 mm × 37 mm × 6 mm and weight of 13.4 grams. It consists of two main parts: 1) a combined detection and stimulation module with wireless charging circuit and 2) a real-time remote control program. To evaluate the WNIS performance, we recorded local field potentials (LFPs) from the dorsal surface of the lumbosacral spinal cord segments and stimulated the pelvic nerves in female rats. Results : Developed system is capable of acquiring eightchannel neural signals and delivering programmed electrical stimulations with two implemented channels for neuromodulation. The acquired LFPs from in vivo experiments showed a high correlation with gradual urinary bladder distension, and the stimulation test performed in pelvic nerves induced bladder contractions and pressure increments. Conclusions : The proposed WNIS was successfully applied to wireless neural signal acquisitions and neuromodulations. This work will provide fundamental concepts for simplified experimental devices.restrictio

저 전력 능동조정인덕터 설계와 그 응용

학위논문(박사) - 한국과학기술원 : 전기및전자공학과, 1997.2, [ x, 109 p. ]This thesis is composed of three parts, which deal with some of contemporary issues in monolithic microwave integrated circuit. Firstly, the main body of this thesis is on two tunable active inductors with emphasis on low power consumption. Experimental measurement results of our active inductor (based on GaAs MESFET) show that the power consumption of the proposed scheme is about 1/3 of the conventional ones with wider range of tunability and higher Q. The simulation results of our active inductor (based of Si BJT) show that the power consumption is about 1/10 of the conventional ones. Further more, the external bias pins are also reduced. This new tunable active inductor is applied to wideband monolithic tunable oscillator and wide tunable bandpass filter. In appendix I, we suggest low power, new monolithic, tunable, recursive filters having variable and uniform gain. We change the location of amplifier to achieve high gain in 1st-order recursive filter. We use the cascode amplifier as variable gain amplifier to get the variable and uniform gain. To achieve higher Q and low power consumption, we make also the 2nd-order filter using only one amplifier. In case of 1st-order recursive filter, the measured results are similar to our estimation and show variable, uniform, and high gain. The measured results of 2nd-order filter show that it has higher Q at the same gain. Our recursive filters can be applied to monolithic tunable narrow bandpass filters for low power operation in modern telecommunications. In appendix II, we present a simple semi-empirical high frequency equivalent circuit model to characterize the coplanar waveguide structure, which consists of relatively thick metal line on very thick polyimide over lossy substrate such as Si BiCMOS wafer. Considering the skin effect, the geometric dependence, and the substrate loss, we derive modified models for the equivalent circuit elements. We verify the validity of our model by comparing it with the exper...한국과학기술원 : 전기및전자공학과

Optimization of Medial Forebrain Bundle Stimulation Parameters for Operant Conditioning of Rats

Background: The medial forebrain bundle (MFB) is involved in the integration of pleasure and reward. Previous studies have used various stimulation parameters for operant conditioning, though the effectiveness of these parameters has not been systematically studied. Objectives: The purpose of the present study was to investigate the optimal MFB stimulation parameters for controlling the conditioned behavior of rats. Methods: We evaluated four factors, including intensity, frequency, pulse duration, and train duration, to determine the effect of each on lever pressure applied by animals. We further compared burst and tonic stimulation in terms of learning and performance abilities. Results: The number of lever presses increased with each factor. Animals in the burst stimulation group exhibited more lever presses. Furthermore, the average speed in the maze among burst stimulation group subjects was higher. Conclusion: We determined the optimal parameters for movement control of animals in operant conditioning and locomotor tasks by adjusting various electrical stimulation parameters. Our results reveal that a burst stimulation is more effective than a tonic stimulation for increasing the moving speed and number of lever presses. The use of this stimulation technique also allowed us to minimize the training required to control animal behavior.restrictio