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YOSHIDA Hisashi

    Department of Computational Systems Biology　Professor/Manager
Last Updated :2024/04/25

Researcher Information

Degree

  • Ph.D.（Hosei University）

J-Global ID

Research Interests

  • Statistical Signal Analysis   Biosignal Analysis   Biosignal Processing   Neural Computing   Image Processing   Statistical Signal Processing   Time-Frequency Analysis   Signal Processing   Signal Processing in Medicine and Biology   

Research Areas

  • Informatics / Intelligent informatics
  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Measurement engineering
  • Life sciences / Biomaterials
  • Life sciences / Biomedical engineering
  • Informatics / Statistical science
  • Informatics / Biological, health, and medical informatics

Academic & Professional Experience

  • 2018/04 - Today  Hosei UniversityGraduate School of Science and EngineeringConcurrent Lecturer
  • 2017/10 - Today  Kindai UniversityFaculty of Biology-Oriented Science and TechnologyChair, Department of Computational Systems Biology
  • 2013/04 - Today  Nara Medical UniversityPart-time lecturer
  • 2012/04 - Today  Kindai UniversityFaculty of Biology-Oriented Science and TechnologyProfessor
  • 2015/04 - 2019/03  Kindai UniversityGeneral Educational Coordinating CommitteProfessor
  • 2012/04 - 2018/03  Kindai UniversityAdvanced Technology Research InstituteProfessor
  • 2014/10 - 2017/09  Kindai UniversityFaculty of Biology-Oriented Science and TechnologyDepartment Chair of Computational Systems Biology
  • 2015/04 - 2017/03  Kindai UniversityAdvanced Technology Research InstituteDirector, Robotics Technology Center
  • 2016/05 - 2016/09  Kindai UniversityFaculty of Biology-Oriented Science and TechnologyAssisant Dean
  • 2012/10 - 2014/09  Kindai UniversityComputer Center, Faculty of Biology-Oriented Science and TechnologyDirector of Computer Center, Faculty of Biology-Oriented Science and Technology
  • 2012/10 - 2014/09  Kindai UniversityFaculty of Biology-Oriented Science and TechnologyDepartment Chair of Electronic Systems and Information Engineering
  • 2011/04 - 2012/03  Kindai UniversityAdvanced Technology Research InstituteAssociate Professor
  • 2006/04 - 2012/03  Kindai UniversityFaculty of Biology-Oriented Science and TechnologyAssociate Professor
  • 2010/06 - 2010/09  Wakayama UniversityPart-time lecturer
  • 2005/04 - 2006/03  Kindai UniversityFaculty of Biology-Oriented Science and TechnologyAssociate Professor
  • 2001/04 - 2005/03  Kindai UniversityFaculty of Biology-Oriented Science and TechnologyLecturer
  • 2001/09 - 2002/08  The City University of New YorkDepartment of Physics & Astronomy, Hunter CollegeVisiting Faculty
  • 1995/04 - 2001/03  Kindai UniversityFaculty of Biology-Oriented Science and TechnologyResearch Assistant
  • 1992/04 - 1995/03  Aeronautical Safety College (Ministry of Transport)Department of Aeronautical InformationPart-time lecturer

Education

  • 1992/04 - 1995/03  Hosei University  Graduate School, Division of Engineering  電気工学専攻 博士後期課程
  • 1990/04 - 1992/03  Hosei University  Graduate School, Division of Engineering  電気工学専攻 修士課程
  • 1986/04 - 1990/03  Hosei University  工学部  電気工学科電気電子専攻

Association Memberships

  • THE INSTITUTE OF IMAGE INFORMATION AND TELEVISION ENGINEERS   （社）自働計測制御学会   日本エム・イー学会   アメリカ電気電子学会(The Institute of Electricaland Electronics Engineers, Inc)   電子情報通信学会   

Published Papers

  • Masatake Shinohara; Kazumasa Torimoto; Chie Matsushita; Daisuke Gotoh; Hisashi Yoshida; Toshihisa Saka; Yoshihiko Hirao; Akihide Hirayama; Kiyohide Fujimoto
    BMC urology 22 (1) 130 - 130 2022/08 [Refereed]
     
    BACKGROUND: To develop a nomogram of urinary volume and flow based on the data of Japanese men without lower urinary tract symptoms and multiple flows per participant whose characteristics were clear. METHODS: Overall, 101 Japanese male volunteers without lower urinary tract symptoms aged between 20 and 59 years were enrolled. A portable uroflowmeter (P-Flowdiary®) was used to record urinary information (flow rate and volume) for 2 successive days. The model (quadratic, linear, or logarithmic regression) most fit for the relationship between maximum flow rate and voided volume was determined. The maximum flow rate at > 150 mL was compared among the 20-29-, 30-39-, 40-49-, and 50-59-year age groups. Nomograms appropriate for the age groups were created. RESULTS: The mean age, International Prostate Symptom Score, and Overactive Bladder Symptom Score were 38.5 years, 0.42, and 0.24, respectively. The quadratic regression model was the most fit because its mean coefficient determination was 0.93 ± 0.06. The mean maximum flow rate was significantly lower in the 50-59-year age group (21.8 ± 5.05 mL/s, P < 0.01) than in the younger groups (24.14 ± 4.94, 24.05 ± 6.99, and 24.64 ± 5.72 mL/s). The 2 nomograms are Y = 28.99 {1 - exp(- 0.01 × X)} and Y = 25.67 {1 - exp(- 0.01 × X)} for the 20-49- and 50-59-year age groups, respectively. CONCLUSIONS: The nomogram can predict maximum flow rate based on voided volume in Japanese men aged 20-59 years without lower urinary tract symptoms.
  • Mika Yamamuro; Yoshiyuki Asai; Naomi Hashimoto; Nao Yasuda; Hiroto Kimura; Takahiro Yamada; Mitsutaka Nemoto; Yuichi Kimura; Hisashi Handa; Hisashi Yoshida; Koji Abe; Masahiro Tada; Hitoshi Habe; Takashi Nagaoka; Seiun Nin; Kazunari Ishii; Yongbum Lee
    16th International Workshop on Breast Imaging (IWBI2022) SPIE 2022/07
  • Mika Yamamuro; Yoshiyuki Asai; Naomi Hashimoto; Nao Yasuda; Hiroto Kimura; Takahiro Yamada; Mitsutaka Nemoto; Yuichi Kimura; Hisashi Handa; Hisashi Yoshida; Koji Abe; Masahiro Tada; Hitoshi Habe; Takashi Nagaoka; Seiun Nin; Kazunari Ishii; Yohan Kondo
    Biomedical physics & engineering express 2022/06 [Refereed]
     
    This study investigates the equivalence or compatibility between U-Net and visual segmentations of fibroglandular tissue regions by mammography experts for calculating the breast density and mean glandular dose (MGD). A total of 703 mediolateral oblique-view mammograms were used for segmentation. Two region types were set as the ground truth (determined visually): (1) one type included only the region where fibroglandular tissue was identifiable (called the 'dense region'); (2) the other type included the region where the fibroglandular tissue may have existed in the past, provided that apparent adipose-only parts, such as the retromammary space, are excluded (the 'diffuse region'). U-Net was trained to segment the fibroglandular tissue region with an adaptive moment estimation optimiser, five-fold cross-validated with 400 training and 100 validation mammograms, and tested with 203 mammograms. The breast density and MGD were calculated using the van Engeland and Dance formulas, respectively, and compared between U-Net and the ground truth with the Dice similarity coefficient and Bland-Altman analysis. Dice similarity coefficients between U-Net and the ground truth were 0.895 and 0.939 for the dense and diffuse regions, respectively. In the Bland-Altman analysis, no proportional or fixed errors were discovered in either the dense or diffuse region for breast density, whereas a slight proportional error was discovered in both regions for the MGD (the slopes of the regression lines were -0.0299 and -0.0443 for the dense and diffuse regions, respectively). Consequently, the U-Net and ground truth were deemed equivalent (interchangeable) for breast density and compatible (interchangeable following four simple arithmetic operations) for MGD. U-Net-based segmentation of the fibroglandular tissue region was satisfactory for both regions, providing reliable segmentation for breast density and MGD calculations. U-Net will be useful in developing a reliable individualised screening-mammography programme, instead of relying on the visual judgement of mammography experts.
  • Nagaoka Takashi; Kozuka Takenori; Yamada Takahiro; Habe Hitoshi; Habe Hitoshi; Nemoto Mitsutaka; Tada Masahiro; Tada Masahiro; Abe Koji; Abe Koji; Handa Hisashi; Handa Hisashi; Yoshida Hisashi; Ishii Kazunari; Ishii Kazunari; Kimura Yuichi; Kimura Yuichi
    Advanced Biomedical Engineering (Web) 11 2187-5219 2022/03 [Refereed]
  • Mika Yamamuro; Yoshiyuki Asai; Naomi Hashimoto; Nao Yasuda; Takahiro Yamada; Mitsutaka Nemoto; Yuichi Kimura; Hisashi Handa; Hisashi Yoshida; Koji Abe; Masahiro Tada; Hitoshi Habe; Takashi Nagaoka; Yoshiaki Ozaki; Seiun Nin; Kazunari Ishii; Yongbum Lee
    Medical Imaging 2021: Computer-Aided Diagnosis SPIE 2021/02
  • Yoshida Hisashi; Kitaoka Yoshitaka; Nagano Kaito; Kohama Takeshi
    Transactions of Japanese Society for Medical and Biological Engineering Japanese Society for Medical and Biological Engineering 58 (0) 159 - 159 1347-443X 2020 

    Even when the eye gazes at a certain point of view, the eye moves involuntarily and constantly, which is called fixation eye movement. The fixation eye movement is mainly composed of three components, microsaccade, drift, and tremor. In recent years, there have been many reports showing that the fixation eye motion is under the influence of cognitive mechanisms such as attention. Therefore it is an important index for knowing human cognitive mechanisms. In this research, we propose a new method that tracks the fixation eye movement by using a state space model. The model can separate the fixation eye movement into three components, microsaccade, drift, and tremor. As a result, it was possible to accurately track the fixation eye movement even including the overshoot and undershoot of the microsaccade. In addition, we proposed a new method for microsaccade detection using the median prediction and the Bayesian prediction interval of the fixation eye motion tracking. Compared with conventional methods that detect micro saccades using smoothing differentiation and thresholds, the proposed method can detect microsaccades with high accuracy with taking into account overshoots and undershoots that appear in micro saccades, and the detection rate was also high.

  • 富永滋; 吉田久; 中迫昇; 岩城達也
    電子情報通信学会論文誌 D(Web) J102-D (5) 399‐410 (WEB ONLY)  1881-0225 2019/05 [Refereed]
  • 小濱 剛; 吉田 久
    映像情報メディア学会技術報告 43,37 33 - 36 2019
  • A Method of Connectivity Analysis of Epileptiform Discharges During Epileptic Seizure
    Hisashi Yoshida; Yasuhito Yoshioka; Masaharu Miyauchi; Naoki Nakano; Amami Kato
    International Journal of Bioelectromagnetism 19 (1) 6 - 10 2017/12 [Refereed]
  • OKAMOTO Ryota; KOBAYASHI Aoi; KOHAMA Takeshi; YOSHIDA Hisashi
    ITE Technical Report The Institute of Image Information and Television Engineers 41.09 (9(HI2017 53-61/3DIT2017 9-17)) 25 - 28 1342-6893 2017/03 
    In recent years, functional near-infrared spectroscopy (fNIRS) measurement technique that can measure brain function unconstrained in a normal laboratory environment attracts attention. However, the skin blood flow fluctuations due to various factors which are easily misunderstood as brain activities, are mixed as large artifacts in fNIRS signals. When measuring brain activity by fNIRS, sufficient consideration is necessary for the designs of experiments and analysis methods. In this study, in order to examine the experimental conditions and analysis procedures suitable for brain function measurement by fNIRS, event-related fNIRS measurement was performed when a subject was observing blinking checkered fag patterns. The brain function components were extracted from the measurement fNIRS signals by using a blood flow dynamics model and applied a model based analysis method using a general linear model. The results suggest that the activation of the primary visual cortex and the secondary visual cortex is detected in synchronization with the presentation of the visual stimulus. This indicates that the proposed method is effective to measure brain functions by using fNIRS.
  • 小濱剛; 中井裕真; 大谷尚平; 山本雅也; 上田慎一; 吉田久
    ヒューマンインタフェース学会論文誌(CD-ROM) 19 (1-4) 189‐197  2186-828X 2017/02 [Refereed]
  • Kohama Takeshi; Nakai Yuma; Ohtani Shohei; Yamamoto Masaya; Ueda Shinichi; Yoshida Hisashi
    The Transactions of Human Interface Society Human Interface Society 19 (2) 189 - 198 1344-7262 2017 [Refereed]
     
    Voice recognition technologies are widely applied to the general-purpose devices, such as car navigation systems or mobile phones. However, cognitive-loads of voice operations have not been discussed sufficiently. Since it is necessary to translate a command to a verbal phrase, cognitive-loads of voice operations for simple tasks may become higher than those of manual operations. In this study, we analyzed microsaccade rates to compare the cognitive-loads between voice and manual operations objectively. Subjects performed a parafoveal transition detection task of a geometry pattern in which they responded by their voice or mouse clicks. We also evaluated the task performances of simultaneously imposed an RSVP (Rapid Serial Visual Presentation) task to estimate effects on cognitive distractions. The results show that microsaccade rates increase synchronously with the timing of voice responses, and task performances of the RSVP task decline immediately after voice responses compared with the results of manual responses. These findings suggest that voice operations have an effect to disengage subjects' attention from visual targets, and this attentional disengagement might cause the cognitive distraction of gazing objects.
  • Shohei Otani; Takeshi Kohama; Sho Kikkawa; Hisashi Yoshida
    International Journal of Bioelectromagnetism 18 (1) 19 - 25 2016/12 [Refereed]
  • KIKKAWA SHO; KOHAMA TAKESHI; YOSHIDA HISASHI
    Mem Fac Biol Oriented Sci Technol Kinki Univ (36) 9 - 17 1342-7202 2015/09 [Refereed]
  • KUBO KENSUKE; KOHAMA TAKESHI; YOSHIDA HISASHI
    電子情報通信学会技術研究報告 電子情報通信学会 115 (232(HIP2015 72-87)) 55 - 60 0913-5685 2015/09
  • Hisashi Yoshida; Takeshi Kohama
    PERCEPTION SAGE PUBLICATIONS LTD 44 113 - 113 0301-0066 2015/08 [Refereed]
  • Takeshi Kohama; Makoto Nishino; Hisashi Yoshida
    PERCEPTION SAGE PUBLICATIONS LTD 44 166 - 166 0301-0066 2015/08 [Refereed]
  • HONDA SHOGO; KOHAMA TAKESHI; YOSHIDA HISASHI
    映像情報メディア学会技術報告 The Institute of Image Information and Television Engineers 39 (11(HI2015 45-55/3DIT2015 11-21)) 25 - 28 1342-6893 2015/03 
    Previous studies have shown that microsaccade (MS) rates increase and pupil diameters continuously constrict antecedent to the occurrence of slow eye movements (SEMs). Since SEMs occur in connection with the depression of arousal, fixation eye movements and pupil fluctuations are candidate indicators to monitor arousal states. However, SEM detection methods of these studies are not sufficiently accurate. In this study, we propose a new SEM detection method to extract SEMs as sections and analyze MS rates and pupil fluctuations before the starting point of each SEM section. The results clearly show that gradual rise of MS rate and longitudinal miosis are observed prior to the initiation of SEMs, and these properties become more distinctive when they are restricted to primal SEMs. Moreover, we performed similar experiment using more precise equipment and the results show that periodical MS rate heave associated with nystagmus appears approximately two minutes prior to SEMs. This indicates that these profiles might be able to be used to estimate arousal states quantitatively.
  • TOKUDOME Ken; KOHAMA Takeshi; KIKKAWA Sho; YOSHIDA Hisashi
    ITE Technical Report 一般社団法人映像情報メディア学会 39 (11) 21 - 24 1342-6893 2015/03 
    In this study, we propose a mathematical model of fixation eye movements controlled by visual attention mechanisms to establish an index for quantitative evaluation of higher-order cognitive functions. It is known that Mean Square Displacement (MSD) profiles of fixation eye movements show a crossover phenomenon (Engbert & Kliegl. 2004), which indicates that multiple external factors contribute to control of movements. We formulated a model based on a hypothesis that stable gazing is controlled by rectifying retinal errors by drifts and microsaccades. Simulation results suggest that fractional Brownian motion and continuous feedback to correct gaze positions yield the MSD profile of fixation eye movements. Furthermore, microsaccades contribute to modulate the MSD profile during short-range lags.
  • NISHINO Makoto; KOHAMA Takeshi; YOSHIDA Hisashi
    ITE Technical Report 一般社団法人映像情報メディア学会 39 (11) 17 - 20 1342-6893 2015/03 
    In this study, we performed a simulation experiments using a mathematical model of a wide-scale retinal network considering the receptive fields' properties in parafovea. Vertical sinusoidal grating patterns and random dot patterns, which consist of particular spacial frequencies, were given as input patterns. We computed the retinal ganglion cells responses which were composed of either a high or a low spacial frequency. Simulation results of grating pattern input suggest that microsaccades enhance the membrane potential of ganglion cells for the low-frequency pattern, and as for the high-frequency patten, it is influenced by drifts and tremor, particularly on the responses of M-type cells under both conditions. On the other hand, they do not influence the activity of M- or P-type cells when any random dot pattern inputs was given. These results suggest that the strength of the effects derived by fixation eye movements on the retinal responses depend on the nature of the input patterns.
  • Mitsuhiro Kodama; Takeshi Kohama; Hisashi Yoshida
    2015 37TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC) IEEE 6658 - 6661 1557-170X 2015 [Refereed]
     
    The purpose of this study is to construct a mathematical model which predicts saliency regions in high-speed egocentric-motion movies, filmed by an embedded camera in a driving vehicle, by reproducing the characteristics of the area MT and MST neurons' receptive fields with consideration of visual adaptation properties. The area MT neurons integrate from the area V1 activation and respond well to regions where higher motion contrasts exist. While the area MST neurons detect global motions such as expansion, contraction, rotation, and so on. We modeled the area MT neurons' receptive fields as a center-surround spatial summation of counter sided motion vectors of visual scenery. The area MST neurons in our model integrate the responses of the MT neurons by convolving with spacial weight functions of which central portions are biased to preferred direction. Visual adaptations were taken as the primary delay filters for each visual feature channel to deplete the saliency of stationary objects and regions during particular frames. The simulation results for the movies which were taken in a running vehicle indicate that the proposed model detects more salient objects around the vanishing point than the conventional saliency based model. To evaluate the performance of proposed model, we defined the moving-NSS (normalized scan-path salience) scores as the averaged NSS scores in each moving time window. The moving-NSS scores for motion images of our model were higher than those of the conventional model.
  • NISHINO MAKOTO; KOHAMA TAKESHI; YOSHIDA HISASHI
    Mem Fac Biol Oriented Sci Technol Kinki Univ 近畿大学生物理工学部 34 (34) 35 - 46 1342-7202 2014/09 
    type:Departmental Bulletin Paper [要旨] 本研究では, 周辺視野の特性を考慮した網膜数理モデルを対象に, 計算資源の制限の中で計算処理を最大限に効率化することを目的として, 種々の並列計算アルゴリズムを適用し, 富士通製並列計算機PRIMEHPC FX10と汎用のパーソナルコンピュータとの間で計算時間の比較を行った. その結果, 各種の神経細胞層を個別のモジュールとして扱うことで，メッセージ通信によるサイクリック分割とパイプライン通信が実装可能であり，微分方程式の回帰参照の問題が回避できることが示された. また, メッセージ通信が困難な部分にマルチスレッド並列を適用することにより, 効率的な並列処理が実現できた. これらのことから, FX10の性能を最大限に引き出すためには, MPI（Message Passing Interface）を用いたメッセージ通信と, マルチスレッド処理とのハイブリッド並列化が有効であり, これにより高効率で高速な並列計算が可能となることが示された. [Abstract] The purpose of this study is to develop effective methods to compute a mathematical model of the retina which considers peripheral properties of retinal cells in the restriction of computation resources. We compared the machine time with regard to several parallel processing algorithms between the Fujitsu PRIMEHPC FX10 supercomputer system and general personal computers. The results indicate that the implementation of cyclically divided blocks and a pipeline processing with a message passing interface, by dealing with each cell layer as a module, is able to avoid problems of the regression reference of calculation of differential equations. For program codes which are difficult to implement message passing interfaces, we obtained a practical solution by applying multithread processing instead. Furthermore, these results suggest that the performance of the FX10 system is maximized by using a hybrid parallel processing method with message passing interfaces and multithread processing.
  • KOHAMA TAKESHI; KIKKAWA SHO; YOSHIDA HISASHI
    電子情報通信学会技術研究報告 114 (226(HIP2014 43-59)) 87 - 92 0913-5685 2014/09
  • TOMINAGA SHIGERU; YOSHIDA HISASHI; NAKASAKO NOBORU
    電子情報通信学会技術研究報告 114 (51(MBE2014 1-11)) 37 - 42 0913-5685 2014/05
  • NOGUCHI Daisuke; KOHAMA Takeshi; KIKKAWA Sho; YOSHIDA Hisashi
    ITE Technical Report 一般社団法人映像情報メディア学会 38 (10) 45 - 48 1342-6893 2014/02 
    The purpose of this study is to evaluate the effect of visual attention on the dynamics of drift eye movements objectively. We proposed a signal processing method to separate drift eye movements and microsaccades from fixation eye movements in the experiments which control attentional concentration to the foveal region, and compared the properties of extracted drift eye movements between the conditions of attentional intensities. In our method, microsaccades are detected by using an order-statistic low-pass differentiation filter. The start- and end-point of each microsaccades is discriminated by a discrete pulse transform analysis, then microsaccades are removed from the data. These gaps are filling through the use of an autoregressive model to extract pure drift eye movements. After the extraction of drift eye movements, we analyzed the frequency components and mean-square displacements to examine the fluctuation properties of the drifts. As results, drift eye movements were not influenced by the foveal attention allocation, rather affected by diffusing attention to the peripheral visual field.
  • Takeshi Kohama; Daisuke Noguchi; Sho Kikkawa; Hisashi Yoshida
    I-PERCEPTION PION LTD 5 (4) 310 - 310 2041-6695 2014 [Refereed]
  • Shogo Honda; Takeshi Kohama; Tatsuro Tanaka; Hisashi Yoshida
    2014 36TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC) IEEE 2014 2229 - 2232 1557-170X 2014 [Refereed]
     
    It is well known that a decline of arousal level causes of poor performance of movements or judgments. Our previous study indicates that microsaccade (MS) rates and pupil fluctuations change before slow eye movements (SEMs) (Honda et al. 2013). However, SEM detection of this study was obscure and insufficient. In this study, we propose a new SEM detection method and analyze MS rates and pupil fluctuations while subjects maintain their gaze on a target. We modified Shin et al.'s method, which is optimized for EOG (electrooculography) signals, to extract the period of sustaining SEMs using a general eye tracker. After SEM detection, we analyzed MS rates and pupil fluctuations prior to the initiation of SEMs. As a result, we were able to detect SEMs more precisely than in our previous study. Moreover, the results of eye movements and pupil fluctuations analyses show that gradual rise of MS rate and longitudinal miosis are observed prior to the initiation of SEMs, which is consistent with our previous study. These findings suggest that monitoring eye movements and pupil fluctuations may evaluate the arousal level more precisely. Further, we found that these tendencies become more significant when they are restricted to the initial SEMs.
  • TOMINAGA SHIGERU; YOSHIDA HISASHI; NAKASAKO NOBORU
    電子情報通信学会技術研究報告 113 (373(MBE2013 75-92)) 57 - 62 0913-5685 2013/12
  • KOHAMA TAKESHI; YOSHIDA HISASHI; YAMAWAKI NOBUYUKI; HAMANO YUKI; SHIMIZU TATSUO
    Memoirs of the Faculty of Biology-Oriented Science and Technology of Kinki University 近畿大学生物理工学部 32 (32) 7 - 16 1342-7202 2013/09 
    [要旨] 従事すべき作業とは関係の無い考え事に注意が奪われている状態では, 覚醒水準とは無関係に判断や応答といった認知パフォーマンスが低下するため, 判断ミスなどのヒューマンエラーによる事故をもたらす危険性が高くなるが, 作業者がそうした状態に陥っていることを客観的に評価することは極めて困難である. 本研究では, 課題とは無関係な考え事をしている状態を課題非依存性思考状態と定義し, このような課題非依存性思考状態が, 認知パフォーマンスに与える影響の客観的な評価を目的として, あらかじめ提示された8桁の数字の記憶を維持しつつ, 同時に課せられた視覚探索課題を遂行する際の, 目標探索時間や前頭前野外側部の近赤外線スペクトロスコピー(Near-Infrared Spectroscopy: NIRS)信号を解析した. 実験の結果, 複数の視覚属性の組み合わせにより定義された視対象の中から唯一の特徴を持った目標を探索する場合においてのみ, 課題非依存性思考の有無により目標探索時間が影響されることが示された.また, この条件においてはNIRS信号から推定された前頭前野外側部の賦活度が高まることも示唆された.これらのことから, 課題非依存性思考によって前頭前野の情報処理リソースが消費されることが示唆され, こうした状況下では, 認知タスクのパフォーマンスが影響を受ける可能性が示された. [Abstract] Working with stimulus-independent thoughts(SITs) often causes the decline of cognitive performances, such as judgments of signals or response times to certain tasks. It might lead to fatal accidents called "human errors" independently of arousal level. The detection and prediction of these errors is extremely difficult, and the measurement technology of inattentiveness has not yet been established. In this study, we investigate the effect of SITs on the performance of visual search tasks. SITs are the streams of thoughts that are unrelated to immediate situations. The subjects memorized the numeral of eight digits as an SIT while carrying out visual search tasks. The reaction time and the near-infrared spectroscopy signals from the lateral prefrontal cortex(PFC) were analyzed to evaluate the effect of SITs objectively. As a result, the average reaction time for searching targets from distracters only in terms of their feature conjunctions increased when having SITs during the tasks. Also, the SITs in these tasks enhance the activity of the lateral PFC. These results suggest that the SITs occupy the resource of attention and it might affect the performances of certain cognitive tasks under these conditions.【注記】本研究は, 近畿大学生物理工学部戦略的研究NO.11-Ⅰ-3 2012, および, JSPS科研費24560534の助成を受けた.
  • TOMINAGA SHIGERU; YOSHIDA HISASHI; NAKASAKO NOBORU
    電子情報通信学会技術研究報告 113 (223(NC2013 22-45)) 113 - 118 0913-5685 2013/09
  • Shogo Honda; Takeshi Kohama; Tatsuro Tanaka; Hisashi Yoshida
    2013 35TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC) IEEE 2013 2108 - 2111 1557-170X 2013 [Refereed]
     
    In this study, we proposed an objective estimation of decline of arousal level by analyzing microsaccade rate and pupil fluctuation while subjects were continuously gazing a fixation target. Previous studies show that the slow eye movements (SEMs) could be a candidate for an indicator of decline of arousal. However, it is not sufficient to evaluate transition of arousal states since SEMs appear just prior to sleep onset. To establish more objective assessment of arousal, we examined the effects of the transition of arousal on microsaccade rate and pupil fluctuation. The subjects were instructed to indicate by mouse clicks when they were aware of having slept. We have analyzed the eye movement and pupil fluctuation data in advance of the occurrence of SEMs which were detected just before the mouse clicks. In the results, longitudinal pupil diameter shrinking and gradual rise of microsaccade rate were observed prior to SEMs. These results suggest that the arousal level could be evaluated by monitoring eye movements and pupil fluctuations.
  • Yamamoto Hiroki; Yoshida Hisashi
    BME Japanese Society for Medical and Biological Engineering 51 U - 22-U-22 1347-443X 2013
  • 小濱 剛; 吉田 久; 北林勇弥; 兵藤宏紀
    Memoirs of the Faculty of Biology-Oriented Science and Technology of Kinki University 近畿大学生物理工学部 30 1 - 16 1342-7202 2012/09 
    [要旨]手振れのような振動や回転を含んだ映像は, 吐気や目眩などの乗り物酔いと同様の症状を引き起こす. この症状を映像酔いと呼ぶ. 本研究では, 映像酔を誘発する映像要素を特定することを目的として, 特定の運動成分からなる映像を観察中の主観的な酔いの程度と固視微動および心拍変動の解析を行った. 映像が水平方向に移動するパン, 回転方向に変移するロール, 拡大と縮小により生じるズームの3種の映像要素により構成される運動するランダムドットパターン(ダイナミックランダムドット)を観察中に計測された固視微動データに対して周波数解析を行った結果, 実験の進行に伴って徐々に視線の揺らぎが増し, 注視の維持が困難になることが示された. また, パンまたはロール成分のみからなる動画を観察する際の心拍変動を解析した結果, パン成分のみの映像の方が, 心拍変動のHRV(HF/LF)が低い値となることが明らかとなり, パン成分が交感神経の亢進をもたらすことが示唆された. これらの結果から, 水平方向の運動成分を持った映像を長時間視聴することによって生じる視覚系と前庭系および体性感覚系との矛盾の蓄積が, 映像酔いをもたらしているものと推察され, 固視微動や心拍変動から酔いの進行の定量化が可能であることが示された. [Abstract] Videos with camera shake containing strong vibrational or rotational motion may cause some symptoms similar to motion sickness such as nausea, dizziness and headache. It is called cybersickness, or visually induced motion sickness. In this paper, we have evaluated cybersickness by analyzing fixation eye movements and heart rate variability of subjects viewing videos of which content was restricted to certain visual factors in order to identify the effective motion component for cybersickness. Firstly, fixation eye movements while subjects were watching random dots which consist of each of three visual factors, such as Pan, Roll and Zoom were measured and evaluated by spectral analysis. The results show that variability of the eye movements is increased as the experiment session progresses and it suggests that it is difficult to maintain the attention of fixation as cybersickness progresses. Secondly, we have evaluated the heart rate variability while subjects were watching the motion pictures which are not random dots but well-controlled motion pictures of an indoor scene and an out outdoor scene. Spectral analysis of the heart rate variability demonstrates that HF/LF measure in the Pan condition has lower values than in the Roll condition and it suggests that Pan motion in the video increases sympathetic nerve activity. These results indicate that cybersickness is caused by cumulative inconsistencies among visual, vestibular, and somatosensory systems for a long time while watching videos. Also, we have shown that progression of sickness can be quantified by analyzing fixation eye movements and heart rate variability.本研究は近畿大学生物理工学部戦略的研究No.07-I-02, 2007の助成を受けた.
  • Hisashi Yoshida; Youki Tanaka; Sho Kikkawa
    2012 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC) IEEE 2012 2933 - 2936 1557-170X 2012 [Refereed]
     
    This paper describes EEG analysis of frontal lobe area in arousal maintenance state against sleepiness. Arousal maintenance state is considered different physiological state from the normal sleep onset. To analyze the EEG of frontal area might be important because we believe that the arousal maintenance state against sleepiness causes neuron activities from the frontal lobe, which coordinates behavior, to hypothalamus, which coordinates wakefulness and sleep. It is, however, hard to use EEG signals in the frontal area consistently because blinking artifacts are mixed in the EEG signals. In this paper, we have analyzed the EEG signals of the frontal lobe in arousal maintenance state against sleepiness after removing the eye-blinking artifact from the scalp EEG signals using an ICA denoising method. As a result, the EEG signals of the frontal area in the arousal maintenance state against sleepiness have wide band width as in the EEG of the occipital area. It strengthen sour speculation, i.e., the EEG desynchronization occurs because of the neuron activities from the frontal lobe to hypothalamus in order to maintain arousal state against sleepiness
  • Hisashi Yoshida; Sho Kikkawa
    2011 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC) IEEE 2011 3845 - 3848 1557-170X 2011 [Refereed]
     
    Recently, we have developed a new method to analyze brain activity from electroencepharogram (EEG) based on a concept of instantaneous equivalent bandwidths (IEBWs). The essence of the method using the IEBW is to track bandwidths changes of EEG signals. Arousal maintenance state against sleepiness can be considered to be in a different physiological state compared to the normal sleep onset. The method was therefore applied to the EEG signals in the wakefulness maintenance state against sleepiness in order to capture the feature of the EEG signals. As a result, we have revealed that EEG signals while the subjects were trying to maintain wakefulness state against sleepiness had wide bandwidth compared to the EEG signals in normal sleep onset because of the EEG desynchronization. It can be considered that neuron activities from the frontal association area which coordinates behavior to hypothalamus which coordinates wakefulness and sleep were raised in order to maintain wakefulness state against sleepiness. Meanwhile, it is considered that EEG activity in gamma band is influenced by muscle activity. We therefore measured electromyograms (EMG) at mentalis muscle and trapezius muscle in order to evaluate the influence of the EMGs for the EEGs. The results showed that the EMG and the EEG were not correlated each other.
  • Takeshi Kohama; Haruka Takenaka; Hisashi Yoshida; Naohiro Toda
    Kyokai Joho Imeji Zasshi/Journal of the Institute of Image Information and Television Engineers 映像情報メディア学会 64 (12) 1892 - 1898 1342-6907 2010/12 
    Recent studies have demonstrated a close relationship between the frequency of microsaccades and covert attention shift. However, there are no arguments of attentional effect on drift movements during attentive or inattentive fixation. We examined whether visual attention has any influence on drift eye movements using statistical analysis of a time series of fixation eye movements. The results indicated that the power in the 3-4 Hz frequency range was enhanced when visual attention was dispersed over the parafoveal visual field. Furthermore, the amplitudes of the drift eye movements were reinforced immediately after the microsaccades, especially after square-wave jerks. These results suggest that microsaccades and drift eye movements are both controlled by higher order brain functions to acquire detailed visual information from the peripheral vision.
  • 小濱 剛; 吉田 久
    Proceedings of the Fourth International Workshop on Image Media Quality and Its Anolications 96 - 99 2010 [Refereed]
  • 小濱 剛; 吉田 久
    Proceedings of the Forth International Workshop on Image Media Quality and Its Applicatoins 96 - 99 2010 [Refereed]
  • 小濱 剛; 吉田 久
    Proceedings of the Fourth International Workshop on Image Media Quality and Its Applications 96 - 99 2010 [Refereed]
  • Analysis of Desynchronized Brain Activity in Wakefulness Maintenance State against Sleepiness by Instantaneous Equivalent Bandwidth
    吉田 久
    Proceedings of the 6th International Workshop on Biosignal Interpretation 388 - 391 2009/06
  • Akimichi Morita; Yoichi Shintani; Emi Nishida; Hiroshi Kato; Hisashi Yoshida; Maki Minamoto; Yuji Yamaguchi; Akira Maeda
    PHOTODERMATOLOGY PHOTOIMMUNOLOGY & PHOTOMEDICINE WILEY-BLACKWELL PUBLISHING, INC 25 (1) 41 - 44 0905-4383 2009/02 [Refereed]
     
    Narrow-band ultraviolet B (NB-UVB) for the treatment of refractory skin diseases, such as psoriasis and atopic dermatitis, requires an adequate irradiation protocol based on the minimal erythema dose (MED) to establish an optimal dosage schedule. Although MED can be measured using a systemic-type irradiation unit, there are difficulties associated with this device. There is no standardized device available to determine the MED for NB-UVB. Here, we compared a conventional device with a newly developed device for measuring MED. MED was measured in 16 psoriasis patients using both a conventional measuring device and the newly developed device, which comprised a hand-held NB-UVB (311-313 nm) flat-type fluorescent lamp with neutral density filters having different transmittances ranging from 10% to 90%. This device was designed to be stably maintained on the skin surface and to provide a highly accurate measurement with only one UV irradiation exposure while also preventing UV radiation from leaking to nonirradiated areas. The MED values obtained from each patient were the same using both devices. One-time irradiation using the new hand-held device with the NB-UVB flat-type fluorescent lamp is feasible and accurate for determining the MED to use in calculating the UV irradiation treatment dose.
  • Hisashi Yoshida; Isao Fujimoto; Sho Kikkawa
    ADVANCED SIGNAL PROCESSING ALGORITHMS, ARCHITECTURES, AND IMPLEMENTATIONS XVIII SPIE-INT SOC OPTICAL ENGINEERING 7074 0277-786X 2008 
    We develop an automatic smoothing procedure for an estimate of the spectral density of a random process. The procedure is based oil smoothing the periodogram with variable bandwidth and a spline interpolation. Effective varying bandwidth is obtained by approximating the log periodogram with a step function whose positions of level changes are determined using a, dynamic programming technique. We show that the step function can be obtained by minimizing the cost function D(C parallel to mu(k)) for a given K. The number of partitions K also can be chosen by minimizing another cost function L(K). Some numerical examples show that the resulting estimates are shown to be good representations of the true spectra.
  • EEG analysis based on Independent Component Anlaysis and positive time-frequency distribution
    中迫 昇; 吉田 久; 山脇 伸行
    近畿大学生物理工学部紀要 近畿大学生物理工学部 (19) 23 - 35 2007/04
  • H. Yoshida; S. Kikkawa
    METHODS OF INFORMATION IN MEDICINE SCHATTAUER GMBH-VERLAG MEDIZIN NATURWISSENSCHAFTEN 46 (2) 110 - 116 0026-1270 2007 
    Objectives: Since most of the biomedical signals, such as electroencephalogram (EEG), electromyogram (EMG) and phonocardiogram (PCG), are nonstationary random processes, the time-frequency analysis has recently been extensively applied to those signals in order to achieve precise characterization and classification. In this paper, we hove first defined a new class of information theoretic equivalent bandwidths (EBWs) of stationary random processes, then instantaneous EBWs (IEBWs) using nonnegative time-frequency distributions have been defined in order to track the change of the EBW of a nonstationary random process. Methods: The new class of EBWs which includes spectral flatness measure (SFM) for stationary random processes is defined by using generalized Burg entropy. Generalized Burg entropy is derived from the relation between Renyi entropy and Renyi information divergence of order a. In order to track the change of EBWs of a nonstationary random process, the IEBWs are defined on the nonnegative time-frequency distributions, which are constructed by the Copula theory. Results: We evaluate the IEBWs for a first order stationary auto-regressive (AR) process and three types of time-varying AR processes. The results show that the IEBWs proposed here properly represent a signal bandwidth. In practical application to PCGs, the proposed method was successful in extracting the information that the bandwidth of the innocent systolic murmur was much smaller than that of the abnormal systolic murmur. Conclusions: We have defined new information theoretic EBWs and have proposed a novel method to track the change of the IEBWs. Some computer simulation showed effectiveness of the methods. Applying the IEBWs to PCGs, we could extract some features of a systolic murmur.
  • Hisashi Yoshida; Haruka Kuramoto; Yusuke Sunada; Sho Kikkawa
    Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings 19 - 22 0589-1019 2007 [Refereed]
     
    This paper proposes a new method for analyzing brain activity from Electroencephalogram (EEG) based on a concept of instantaneous equivalent bandwidths (IEBWs). The essence of the method using the IEBW is to track bandwidths changes of EEG signals. The instantaneous equivalent bandwidths are defined using positive time-frequency distributions. However, it is well known that non-negative bilinear distributions that satisfy the marginals do not exist. To solve the problem, Copula-based time-frequency distributions have been adopted and we have also modified the construction method suitable for non-stationary random signals. The method was applied to EEG analysis in the wakefulness maintenance state against sleepiness. In our present study, sporadic synchronization was shown in the EEG signals while the subjects were trying to maintain wakefulness against sleepiness. That is, synchronization and desynchronization seem to succeed each other in the period. The results imply that the proposed method can track the EBWs change of EEG signals. © 2007 IEEE.
  • Hisashi Yoshida; Haruka Kuramoto; Yusuke Sunada; Sho Kikkawa
    2007 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-16 IEEE 19 - + 1094-687X 2007 [Refereed]
     
    This paper proposes a new method for analyzing brain activity from Electroencephalogram (EEG) based on a concept of instantaneous equivalent bandwidths (IEBWs). The essence of the method using the IEBW is to track bandwidths changes of EEG signals. The instantaneous equivalent band-widths are defined using positive time-frequency distributions. However, it is well known that non-negative bilinear distributions that satisfy the marginals do not exist. To solve the problem, Copula-based time-frequency distributions have been adopted and we have also modified the construction method suitable for non-stationary random signals. The method was applied to EEG analysis in the wakefulness maintenance state against sleepiness. In our present study, sporadic synchronization was shown in the EEG signals while the subjects were trying to maintain wakefulness against sleepiness. That is, synchronization and desynchronization seem to succeed each other in the period. The results imply that the proposed method can track the EBWs change of EEG signals.
  • Yoshida H; Kuramoto H; Sunada Y; Kikkawa S
    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference 2007 19 - 22 1557-170X 2007 [Refereed]
  • A Comparative Study of The Performance of Population Mixture Models for Image Thresholding
    吉田 久
    Memoirs of The School of B.O.S.T. of Kinki University (17) 7 - 14 2006/03
  • H Yoshida; T Ikegami; S Kikkawa
    PROCEEDINGS OF THE 26TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-7 IEEE 26 388 - 391 1094-687X 2004 [Refereed]
     
    This paper introduces a method for time-frequency analysis of the phonocardiogram. The proposed method is a modified version of the copula-based technique, which constructs positive time-frequency distributions, so as to be suitable for the analysis of periodically stationary random processes. The copula-based time-frequency distributions have some desirable properties: positivity, correct marginals and low computational cost. We use averaged spectrogram as a template in copula-based technique in order to construct a positive time-frequency distribution of the phonocardiogram. Results clearly show that the copula-based time-frequency distributions have much better resolution in time and frequency domain than the spectrogram does. Positivity and high resolution depend on the marginals of the distributions will offer excellent potential for estimating local parameters of the distributions, like a instantaneous frequency or instantaneous equivalent bandwidths using Renyi's divergence formulated by the authors.
  • K Yana; H Mizuta; K Kawachi; H Yoshida; K Iida; Y Okubo; M Tohru; F Okuyama
    METHODS OF INFORMATION IN MEDICINE F K SCHATTAUER VERLAG GMBH 36 (4-5) 349 - 351 0026-1270 1997/12 [Refereed]
     
    This paper compares two classifiers: Pseudo Bayesian and Neural Network for assisting in making diagnoses of psychiatric patients based on a simple yes/no questionnaire which is provided at the outpatient's first visit to the hospital. The classifiers categorize patients into three most commonly seen ICD classes, i.e. schizophrenic, emotional and neurotic disorders. One hundred completed questionnaires were utilized for constructing and evaluating the classifiers. Average correct decision rates were 73.3% for the Pseudo Bayesian Classifier and 77.3% for the Neural Network classifier. These rates were higher than the rate which an experienced psychiatrist achieved based on the same restricted data as the classifiers utilized. These classifiers may be effectively utilized for assisting psychiatrists in making their final diagnoses.
  • H Yoshida; H Shino; K Yana
    PROCEEDINGS OF THE 19TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOL 19, PTS 1-6 IEEE 19 1645 - 1647 1094-687X 1997 [Refereed]
     
    This paper proposes the use of instantaneous frequency for the characterization of phonocardiogram, in the range from the first heart sound to systolic heart sound. The data were collected from nation wide phonocardiogram screening of the elementaly school children conducted in Japan. We have estimated instantaneous frequency of the phonocardiogram from averaged Wigner-Ville distribution. The data analysis showed a different change of instanataneous frequency between innocent murmur and pathological murmur. It could provide a new method for classifying the systolic murmur into innocent murmur and pathological murmur.
  • Hisashi Yoshida; Kazuo Yana
    Japanese journal of medical electronics and biological engineering 33 (2) 101 - 108 0021-3292 1995 
    A method to estimate the modulation characteristics of the heart rate by autonomic nervous activities has been discussed. The heart rate (HR) and a calibrated instantaneous lung volume (ILV) signal were simultaneously recorded from fourteen healthy male subjects in variety of conditions including the application of autonomic blocking agent. Randomized breathing technique has been introduced to estimate accurately the transfer characteristic from ILV to HR. The spectral analysis of the heart rate together with estimated transfer characteristics from ILV to HR revealed that the respiratory fluctuations in HR are originated from the parasympathetic nervous activity. This result shows the possibility of non invasive estimation of parasympathetic autonomic modulation of the heart rate. The method will provide us of a new method for the characterization of the heart rate variability. © 1995, Japanese Society for Medical and Biological Engineering. All rights reserved.
  • K YANA; H YOSHIDA; M KOMAI
    ELECTRONICS AND COMMUNICATIONS IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE SCRIPTA TECHNICA PUBL 77 (2) 35 - 44 1042-0967 1994/02 [Refereed]
     
    This paper defines the degree of nonlinearity as a measure for the nonlinearity of the system. A method for estimating the nonlinearity is proposed based on the input and the output time-series signals under the actual condition that the additive observation noise is included. The degree of nonlinearity of the system takes a value between 0 and 1. It approaches 1 when the part of the variational power that cannot be represented by the linear combination of the input increases in the output variation depending on 0-input in the linear system. A multilayer perceptron is introduced as a parametric function which represents the wide class of nonlinear functions needed in the estimation. An example is shown of the family of memoryless and nonlinear systems where the degree of nonlinearity changes from 0 to 1 by the change of the system parameter. An example also is shown of the system with a finite memory having a degree of nonlinearity of 1. By a computer simulation, the validity of the nonlinearity estimation proposed in this paper is demonstrated. The method will be applied effectively to the modeling of the system based on the observed input and output signals.
  • システムの非線形度とニューラルネットを用いた推定
    電子情報通信学会論文誌 J76-A (8) 1097 - 1104 1993
  • ヒトの目における瞳孔径の呼吸性変動
    電子情報通信学会論文誌 J76-D-II (3) 776 - 781 1993

Books etc

  • 安倍, 広多; 石橋, 勇人; 佐藤, 隆士; 松浦, 敏雄; 松林, 弘治; 吉田, 久 オーム社 2022/09 9784274229152 vii, 253p
  • 持ちつ持たれつ生き物とコンピュータ 第1章 目はみるもの見られるもの
    小濱 剛; 吉川 昭; 中迫 昇; 山脇 伸行; 吉田 久; 長江 貞彦; 奥井 順; 辻合 秀一 (Joint work)電気書院 2006/08
  • 例をとおして学ぶ、システム、信号処理そしてプログラミング
    コロナ社 2003
  • オペレーティングシステム(新世代工学シリーズ)(共著)
    オーム社 1999
  • ME用語辞典(用語解説)(分筆)(社)日本エム・イー学会編
    コロナ社 1999
  • Operating System
    Ohmsha, Ltd. 1999
  • 4-4編 確率と統計の用語解説(分筆)「エンサイクロペディア電子情報通信ハンドブック」
    オーム社 1998
  • Encyclopedia Electronics, Information and Communication Handbook, 4-4 Probability and Statistics
    Ohmsh Ltd. 1998
  • Time Domain Methods for Characterizing Respiratory Fluctuations of Heart Rate : Linear Stationary, Non-Stationary and Non-linear Approaches
    Frontiers of Blood Pressure and Heart Rate Analysis, IOS Press 1997
  • Time Domain Methods for Characterizing Respiratory Fluctuations of Heart Rate : Linear Stationary, Non-Stationary and Non-linear Approaches
    Frontiers of Blood Pressure and Heart Rate Analysis, IOS Press 1997
  • ニューラルコンピューティング入門
    海文堂出版 1993

Conference Activities & Talks

  • YOSHIOKA YASUTO; YOSHIDA HISASHI; MIYAUCHI MASAHARU; NAKANO NAOKI; KATO AMAMI
    電子情報通信学会大会講演論文集(CD-ROM)  2015/02
  • HASEGAWA YU; TAKEDA SHOICHI; KOHAMA TAKESHI; YOSHIDA HISASHI
    日本感性工学会大会予稿集(CD-ROM)  2015
  • HASEGAWA YU; TAKEDA SHOICHI; KOHAMA TAKESHI; YOSHIDA HISASHI
    日本感性工学会春季大会予稿集(CD-ROM)  2015
  • NAMIKAWA HIROKI; KOHAMA TAKESHI; YOSHIDA HISASHI
    日本生体医工学会大会プログラム・論文集(CD-ROM)  2014
  • KANO YUJI; KOHAMA TAKESHI; KIKKAWA SHO; YOSHIDA HISASHI
    日本生体医工学会大会プログラム・論文集(CD-ROM)  2014
  • YOSHIOKA YASUTO; YOSHIDA HISASHI; MIYAUCHI MASAHARU; NAKANO NAOKI; KATO AMAMI
    日本生体医工学会大会プログラム・論文集(CD-ROM)  2014
  • Yuji Kanoh; Takeshi Kohama; Sho Kikkawa; Hisashi Yoshida
    Transactions of Japanese Society for Medical and Biological Engineering  2014/01 
    © 2014, Japan Soc. of Med. Electronics and Biol. Engineering. All rights reserved. Recent studies have indicated that mechanisms of microsaccades, involuntary small shifts in gaze, are affected by attention. Most studies have shown that mocrosaccade rates increase with a shift of attention, while others have shown that occurrence of mocrosaccades is inhibited when attention is in foveal region. In this study, we calculated latencies of microsaccades and analyzed the relationship between the spatial extent of attention and latencies of microsaccades. Subjects performed rapid serial visual presentation tasks. Targets were defined by differences in luminance contrast from distractors. We controlled focal attention under two conditions: high-contrast (HC) and low-contrast (LC). Results show that the histogram of latencies of microsaccades have two peaks only in the LC. The second peak was delayed approximately 0.3 sec from the peak of the HC. These results suggest that microsaccades are inhibited when attention is concentrated in foveal region, and disinhibited when attention is disengaged.
  • Yasuto Yoshioka; Hisashi Yoshida; Masaharu Miyauchi; Naoki Nakano; Amami Kato
    Transactions of Japanese Society for Medical and Biological Engineering  2014/01 
    © 2014, Japan Soc. of Med. Electronics and Biol. Engineering. All rights reserved. Epilepsy prevalence is up to about 1% of the population. 25% of these patients have intractable epilepsy. For these patients however, surgery is an effective treatment, therefore accurately determining the propagation path and epileptic foci is a crucial factor in surgical treatment. In this study, we propose a method to analyze connectivity among the brain signals during epileptiform seizure which were recorded from the electrodes directly placed on the cortex. First, we obtained the delay time and maximum value of the correlation function and defined connectivity strength between channels by a linear combination of the two. Then, using the connectivity strength, we configured a minimum spanning tree, which was estimated to be the epilepsy propagation path. As a result, the foci of epilepsy moved slightly for a total of four times for each seizure in the same patient; different propagation paths of the seizure at different times was shown.
  • Hiroki Namikawa; Takeshi Kohama; Hisashi Yoshida
    Transactions of Japanese Society for Medical and Biological Engineering  2014/01 
    © 2014, Japan Soc. of Med. Electronics and Biol. Engineering. All rights reserved. Recent brain science studies have focused on functional connectivity in functional networks. However, experimental conditions are not sufficiently controlled to reduce individual differences in order to make experimental data stable because the definition of resting states is ambiguous. The purpose of this study is to investigate a more stable method of measuring restiong state brain activity. Subjects performed a 2-back task to facilitate activity of the prefrontal cortex temporally. As half-closed eyes help induce a meditative state, we presented low-passed dynamic random-dot patterns (DRD) in the background to make subjects' vision similar to what they would see if their eyes were half-closed. We measured subjects' brain activity with a NIRS device while subjects observed DRDs for 180 seconds. As a result, prefrontal activity decreased earlier as DRDs increased in blurriness. Moreover, brain activity reactivated immediately after reaching the baseline. This suggests that our method may induce stable resting states effectively.
  • A study on superimposition mode of mastication EMG on EEG, and its trial separation on FDICA  [Not invited]
    富永 滋; 中迫 昇; 吉田 久
    電子情報通信学会 MEとバイオサイバネティックス研究会（MBE）  2013/12  岐阜市  電子情報通信学会 MEとバイオサイバネティックス研究会（MBE）
  • A study on EEG lead systems, artifacts mixed into the EEGs when eating, and their classification methods based on ICA  [Not invited]
    富永 滋; 中迫 昇; 吉田 久
    電子情報通信学会 MEとバイオサイバネティックス研究会（MBE）  2013/09  新潟市  電子情報通信学会 MEとバイオサイバネティックス研究会（MBE）
  • Evaluation of visual factors of visually induced motion sickness by analyzing fixation eye movements and heart rate variability  [Not invited]
    吉田 久; 小濱 剛
    35th European Conference on Visual Perception  2013/08  Bremen, Germany  35th European Conference on Visual Perception
  • Persistent inhibition of microsaccades caused by attentional concentration  [Not invited]
    小濱 剛; 吉田 久; 遠藤 翔
    35th European Conference on Visual Perception  2013/08  Bremen, Germany  35th European Conference on Visual Perception
  • A mathematical model for reproducing mean square displacement profile of fixation eye movements  [Not invited]
    徳留 健; 小濱 剛; 吉川 昭; 吉田 久
    Neuro 2013  2013/06  京都府 京都国際会館（6月22日発表）  Neuro 2013
  • An arousal level assessment by analyzing microsaccade rate and pupil fluctuation in preceding period of slow eye movements  [Not invited]
    本田彰吾; 小濱 剛; 吉田 久; 田中達郎
    Neuro 2013  2013/06  京都府 京都国際会館（6月22日発表）  Neuro 2013
  • SOGABE TAKUYA; YOSHIDA HISASHI; AKASAKA KAZUYUKI
    電子情報通信学会大会講演論文集  2013/03  岐阜大学 (岐阜市)  2013 年 電子情報通信学会総合大会
     
    例えは？心電図のように準周期的なハ？ルス信号を検出す ることは,そのハ？ルス生起間隔を計測する上て？重要て？あ る。しかし,胎児心電のようにノイス？混入か？多く,また ハ？ルス波の振幅変動か？大きい場合のハ？ルス検出は容易 て？はない。これまて？に筆者らは信号の非線形変換と移動 平均に基つ？く動的閾値を組み合わせた,リアルタイム処 理に適した心電図における R 波検出法を提案している [1]。本報告て？は,ハ？ルス波と雑音の混合比率を変えたシ ミュレーション信号を作成し,提案手法の有効性をコン ヒ？ュータシミュレーションによって確かめた。
  • YAMAMOTO HIROKI; YOSHIDA HISASHI
    電子情報通信学会大会講演論文集  2013/03  岐阜大学 (岐阜市)  2013 年 電子情報通信学会総合大会
     
    例えは？心電図のように準周期的なハ？ルス信号を検出す ることは,そのハ？ルス生起間隔を計測する上て？重要て？あ る。しかし,胎児心電のようにノイス？混入か？多く,また ハ？ルス波の振幅変動か？大きい場合のハ？ルス検出は容易 て？はない。これまて？に筆者らは信号の非線形変換と移動 平均に基つ？く動的閾値を組み合わせた,リアルタイム処 理に適した心電図における R 波検出法を提案している [1]。本報告て？は,ハ？ルス波と雑音の混合比率を変えたシ ミュレーション信号を作成し,提案手法の有効性をコン ヒ？ュータシミュレーションによって確かめた。
  • A slow eye movement (SEM) detection method for objective evaluations of arousal fluctuations  [Not invited]
    本田彰吾; 小濱 剛; 吉田 久
    映像情報メディア学会2012年冬季大会  2012/12  東京都 東京理科大学森戸記念館  映像情報メディア学会2012年冬季大会
  • HONDA SHOGO; KOHAMA TAKESHI; YOSHIDA HISASHI
    映像情報メディア学会冬季大会講演予稿集(CD-ROM)  2012/11
  • Noninvasive measurement of fetal ECG and heart rate for prenatal care  [Not invited]
    吉田 久; 佐道俊幸; 小林浩
    第48回日本小児循環器学会総会・学術集会  2012/07  京都市(国立京都国際会館)  第48回日本小児循環器学会総会・学術集会
     
    本報告では、母体腹壁上に貼付した複数の電極から観測される多チャンネル生体信号に、高度な信号解析法である独立成分分析法を適用することによって、母体心電位と胎児心電位、およびそれ以外の生体電位と雑音に分離する方法について述べる。さらに、分離した胎児心電位を自動判別する方法ならびに、胎児心電位から胎児心拍数を測定する方法を合わせて述べる。
  • Maternal Healthcare System: a method for fetal ECG detection  [Not invited]
    吉田 久; 山本洋己; 西山昭平; 佐道俊幸; 小林浩
    第56回システム制御情報学会  2012/07  京都市(京都テルサ)  第56回システム制御情報学会
     
    周産期医療の現場では、超音波エコー診断装置などによる妊婦健診によって、妊娠異常の早期発見・早期治療を目指しているが、定期健診では突然起こる妊娠異常を予見できない場合があり、より定常的に妊婦及び胎児の健康状態をモニタリングすることが求められている。本研究では安価かつ小型の装置を用い、また特別な知識や経験を持たずに胎児心拍数を測定する方法として、母体腹壁に貼付した複数の電極から生体電位を計測し、これらから独立成分分析法(ICA: Independent Component Analysis)を利用して、胎児心電を分離し、心拍数を計測する方法を試みた。
  • YOSHIDA HISASHI; SADO TOSHIYUKI; KOBAYASHI HIROSHI
    日本小児循環器学会雑誌  2012/06
  • Copula based Positive Time-Frequency Distribution in Stochastic Processes and Its Application to Biosignals  [Not invited]
    吉田 久; 吉川 昭
    World Congress 2012  2012/05  Beijin, China  World Congress 2012
     
    It is very important to know the time-frequency characteristics of biosignals because they are usually considered non-stationary random signals. However, most of theories of the time-frequency analysis are for the deterministic time varying signals. A positive time-frequency distribution (TFD) is a joint density of time and frequency, which satisfies the marginals and would represent energy distribution (i.e. positive) between the time and frequency variables. In this paper, we show that it is important to accurately estimate the marginals of the time-frequency distribution (TFD) of a random signal, especially when you estimate the TFD based on Copula Theory. firstly, we propose some new methods to estimate temporal marginal and frequency marginal and compare the methods. Then, we give some simulation to evaluate these methods. Finally, we apply the method to real applications, i.e. EEG analysis in wakefulness maintenance state against sleepiness.
  • R wave Detection using nonlinear transform and dynamic thresholding  [Not invited]
    吉田 久; 山本 洋己
    第51回日本生体医工学会大会  2012/05  福岡市  第51回日本生体医工学会大会
     
    Hart rate variability(HRV) is considered as an index of autonomic nervous activity. In order to measure the HRV, it is necessary to detect R waves from ECG and to measure the intervals between consecutive R waves. In the case that ECG artifacts are small, the static thresholding method is very useful for detecting the R waves on a real-time. However, like the fetal ECG(FECG) which is extracted from the maternal abdomen includes electrical interference by outside sources, the static thresholding method often fails to detect the R waves. In this study, we have proposed a method for R wave detection using nonlinear transform and dynamic thresholding.
  • Microsaccade detection based on a discrete pulse transform analysis  [Not invited]
    野口大輔; 吉川 昭; 小濱 剛; 吉田 久
    第51回日本生体医工学会大会（5月10日発表）  2012/05  福岡市  第51回日本生体医工学会大会（5月10日発表）
     
    This study proposes a method for detecting microsaccades based on a discrete ulse transform analysis (DPT). The general methods for microsaccade detection need to decide the threshold for a differentiation signal of eye movements after enoising by the median filter. The median filter well maintain sharp edges configured by microsaccades, however, theoretical prediction of the behavior is difficult.Because of this unpredictability, the trial and error process is necessitated to decide the threshold value or the order of the filters. The proposed method is to detect microsaccades based on the features of the pulse series produced by DPT. The eye movement signal is divided into smoothed and detail components by multiple orders of LULU filters, then the pulse series which represents the dynamics of movements is calculated. The results show the detected microsaccades is more precise than general method. Furthermore,the start- and end-point of each microsaccades is clearly discriminated.
  • Microsaccade detection with a order-statistic low-pass differentiation filter.  [Not invited]
    野口大輔; 小濱 剛; 吉川 昭; 吉田 久
    映像情報メディア学会2011年冬季大会  2011/12  東京 芝浦工業大学  映像情報メディア学会2011年冬季大会
  • Spectral Analysis of Autonomic Nervous Systems in Wakefulness Maintenance State against Sleepiness  [Not invited]
    吉田 久
    第55回システム制御情報学会研究発表講演会  2011/05  吹田市（大阪大学）  第55回システム制御情報学会研究発表講演会
  • Evaluation of arousal level by microsaccade rate and pupil fluctuation  [Not invited]
    田中達朗; 小濱 剛; 吉田 久
    第50回日本生体医工学会大会  2011/04  東京都 東京電機大学神田キャンパス  第50回日本生体医工学会大会
  • Objective evaluation of wakefulness maintenance state against sleepiness and its analysis  [Not invited]
    吉田 久
    日本生体医工学会生体医工学シンポジウム  2010/09  札幌市（北海道大学）  日本生体医工学会生体医工学シンポジウム
  • Effects of motion sickness on fixation eye movements  [Not invited]
    中川 啓; 小濱 剛; 吉田 久
    第49回日本生体医工学会大会  2010/06  大阪市  第49回日本生体医工学会大会
     
    動画像中の激しい振動や急速な回転は，吐気やめまいなどの乗り物酔いと同様の病的な症状を引き起こす．これを映像酔いと呼ぶ．家庭用テレビの大型化や高精細化と相俟って，日常生活における映像酔いのリスクが高まっているものの，映像酔いが生体に及ぼす影響については，未だ全容の解明には至っていない．映像酔いは，視覚情報と前庭系の不調和に依存して発生するものと考えられ，眼球運動制御系への強い関与が予想されるものの，固視微動への影響に関する詳細な解析例はほどんど存在しない．そこで本研究では，映像酔いを生じさせる要素を含んだ映像を一定時間だけ観察する試行を繰り返し実施し，インターバル中の眼球運動を計測して固視微動の解析を行った．固視微動のうち，微小な視線のジャンプとして観測されるマイクロサッカード（MS）は，視覚的注意の集中度合いによって，その発生頻度が変化することが知られている．映像酔いは集中力の低下をもたらす
  • Microsaccade rate varies with arousal level  [Not invited]
    田中達朗; 小濱 剛; 吉田 久
    第49回日本生体医工学会大会  2010/06  大阪市  第49回日本生体医工学会大会
     
    自動車運転等の視覚依存性の高い作業下における覚醒水準の減衰は，視覚機能や運動能力の低下をもたらし，ヒューマンエラーによる事故のリスクを増加させるため，その変動を客観的に捕らえるための判断基準の確立が望まれている．覚醒水準と眼球運動の動的特性との関係を調査した報告によると，高速で断続的な視線のジャンプであるサッカードの最高速度と継続時間の比 PV/D が，覚醒水準と強い相関を示すことが明らかにされているが，ヒューマンエラーに結び付くような危機的状況の直前の変動については検討されていない（植野ら，2000）．そこで本研究では，覚醒水準が低下して睡眠に至る直前に発生するとされる SEM（slow-rolling eye movement）を覚醒維持の限界点として定め，一定間隔 でステップ的に呈示位置を変える視標をサッカードにより追尾させる実験を実施し，SEM 発生に至るまでの PV/D と，サッカード間の固視微動の解析を行った．その結果，PV/D の値が減少す
  • Molecular Dynamics Simulations of R2 Domain in the c-Myb Protein under High-Pressure Conditions  [Not invited]
    吉田 久; 赤坂 一之
    システム制御情報学会第54回システム制御情報学会研究発表講演会  2010/05  京都市（京都リサーチパーク）  システム制御情報学会第54回システム制御情報学会研究発表講演会
  • A Statistical Model Analysis of Attentional Effects on Fixational Drift Eye Movements  [Not invited]
    小濱 剛; 吉田 久; 戸田尚宏
    International Workshop on Image Media Quality and Its Applications (IMQA2010)  2010/05  Tokyo, Japan  International Workshop on Image Media Quality and Its Applications (IMQA2010)
  • Fetal ECG measurement and extraction from maternal ECG  [Not invited]
    吉田 久
    平成21年電気関係学会関西支部合大会  2009/11  平成21年電気関係学会関西支部合大会
  • A spectral estimation method by non-equinterval smoothing  [Not invited]
    吉田 久
    平成21年電気関係学会関西支部連合大会  2009/11  平成21年電気関係学会関西支部連合大会
  • Positive time-frequency distribution based on copula theory and its application  [Not invited]
    吉田 久
    京都大学数理解析研究所共同研究集会（招待）  2009/10  京都市（京都大学）  京都大学数理解析研究所共同研究集会（招待）
  • Preliminary analysis of EEG and autonomic nervous systems in wakefulness maintenance state against sleepiness  [Not invited]
    吉田 久
    第24回生体・生理工学シンポジウム  2009/09  仙台市（東北大学）  第24回生体・生理工学シンポジウム
  • Attentional effects on drift eye movements before and after microsaccades  [Not invited]
    小濱 剛; 吉田 久; 戸田尚宏
    32nd European Conference on Visual Perception  2009/08  Regensburg, Germany  32nd European Conference on Visual Perception
  • A study of simultaneous recordings of EEG and blood pressure during wakefulness maintenance state against sleepiness  [Not invited]
    吉田 久
    第48回日本生体医工学会大会  2009/04  東京都江戸川区（タワーホール船堀）  第48回日本生体医工学会大会
  • A spectral estimation method by non-equinterval smoothing of log periodogram  [Not invited]
    吉田 久
    平成20年電気関係学会関西支部連合大会  2008/11  平成20年電気関係学会関西支部連合大会
  • Equivalent bandwidths by information theoretic divergence and its application to biosignals  [Not invited]
    吉田 久
    第18回インテリジェント・システム・シンポジウム(FAN2008)  2008/10  広島市（広島大学）  第18回インテリジェント・システム・シンポジウム(FAN2008)
  • EEG analysis in wakefulness maintenance state against sleepiness: relationship between gamma frequencies and muscle activity.  [Not invited]
    吉田 久
    第23回生体・生理工学シンポジウム  2008/09  第23回生体・生理工学シンポジウム
     
    筆者らはこれまでに、眠気に逆らいながら覚醒維持の努力を課した場合、脳波の非同期化現象が生じ、等価帯域幅が広がることを見出している。これは大脳皮質から脳幹や視床下部への活発な神経活動によるものであると考えているが、一方で、ガンマ帯域の脳波は筋電の影響を受けているとも言われている。そこで、本研究では眠気に抗して覚醒維持を課した状態における脳波と頤筋と僧帽筋の筋電位を同時測定し、両者の関連性、特にガンマ帯域への影響を、相関係数を用いて評価した。
  • Attentional effects on power spectra for drift eye movements  [Not invited]
    小濱 剛; 吉田 久; 戸田尚弘
    The European Conference on Visual Perception 2008  2008/08  オランダ ユトレヒト  The European Conference on Visual Perception 2008
  • A comparison study of EEG analysis in wakefulness maintenance state against sleepiness and spontaneous sleep induction state  [Not invited]
    吉田 久
    第47回日本生体医工学会大会  2008/05  神戸市(神戸国際会議場)  第47回日本生体医工学会大会
     
    覚醒状態の評価に関する研究報告には、脳波に限らず心拍変動や瞬きなど生理反応を用いた報告例が数多くある。しかしながら、眠気に逆らいながら覚醒を維持しようとする状態の解析例はあまり多くない。本報告では、被験者に座位開眼で読書してもらい、その間に眠気が誘発されても覚醒を維持するように指示した実験、およびその対照実験である眠気に逆らわずに自然入眠するよう指示した実験を行い、両者の脳波を時間－周波数分布と瞬時等価帯域幅を用いて比較した。
  • 対数ペリオドグラムの不等間隔平滑化によるスペクトル推定  [Not invited]
    吉田 久
    電子情報通信学会2008年総合大会  2008/03  北九州研究都市（北九州市立大学）  電子情報通信学会2008年総合大会
     
    ペリオドグラムの平滑化による確率過程のパワースペクトル推定は、通常は 一定幅の窓関数の移動平均によって行われる。その平滑化幅は、統計誤差を低 減するためには長い方が好ましい。しかし、長すぎるとスペクトル形状の変化 に追随できない。こうした問題に対応するため、我々はこれまでにスペクトル 形状の変化に応じて自動的に平滑化幅（不等間隔分割点）を決定する方法を提 案した\cite{Kikkawa-KJCIEE02}。しかしながら、この方法では分割数が大き すぎると分割点がスペクトルのピーク値付近に集中する傾向があったことや、 推定スペクトルが階段状であるなど、改善すべき点があった。本報告では、こ うした点を改良したペリオドグラムの対数領域不等間隔平滑化によるスペクトル 推定法を提案する。
  • IPFMモデルにおける変調信号各種復調法の比較  [Not invited]
    吉田 久
    平成19年電気関係学会関西支部連合大会  2007/11  神戸大学工学部  平成19年電気関係学会関西支部連合大会
     
    IPFMモデルは心拍パルス列のゆらぎを制御する自律神経活動(変調信号)の復調に有用である。これに関して提案された種々復調法の比較が報告されている[2],[4]。しかし比較的最近提案された重み付きsinc関数法(WS法)[1]、パラメトリック法[3]を含む検討は見当たらない。そこで本研究では、 WS法とDCSI法及びAF法の性能を比較した。
  • 眠気に抗した覚醒維持状態における脳波解析 ― 瞬時等価帯域幅による解析 ―  [Not invited]
    吉田 久
    平成19年電気関係学会関西支部連合大会  2007/11  神戸大学工学部  平成19年電気関係学会関西支部連合大会
     
    睡眠脳波に比べ、眠気に抗した覚醒維持状態における脳波の解析例はあまり見られない。本報告ではまず非定常確率過程の解析方法として、情報理論に基づく瞬時等価帯域幅を導入する。この瞬時等価帯域幅は確率過程の正値時間-周波数分布上で定義される。次に覚醒状態、眠気に逆らい覚醒維持を課した状態、および自然入眠状態のそれぞれの状態における脳波の状態変化を提案の瞬時等価帯域幅を用いて解析した結果について報告した。
  • Renyiエントロピーから導かれるRange尺度およびPeak尺度の計算コストと分離性能  [Not invited]
    吉田 久
    平成19年電気関係学会関西支部連合大会  2007/11  神戸大学工学部  平成19年電気関係学会関西支部連合大会
     
    ICAにおいて、理想的条件の元ではシャノンのエントロピー尺度を越えるものはない。しかし、有限データに対して、これが計算コストや分離性能の意味で最良とは限らず、問題に特化した簡素で高速な方法の開発が望まれる。そこで、我々はRenyiのエントロピーに基づくRange尺度およびPeak尺度を提案し、前者は有限レンジデータに対して、後者は音声信号のようにピーキーな分布に対して有効であることを示した。
  • 確率過程における時間－周波数分布の周辺分布推定  [Not invited]
    吉田 久
    平成19年電気関係学会関西支部連合大会  2007/11  神戸大学工学部  平成19年電気関係学会関西支部連合大会
     
    決定論的過程とは異なり、確率過程の時間-周波数表現においては周辺分布を如何に推定するかが重要な問題となる。著者らはこれまでに時間周辺分布の推定方法として、AM型の信号を仮定した「Wigner-Ville分布を用いた包絡線検波法」を提案している。本報告では、時間ー周波数分布におけるもう一方周辺分布、すなわち周波数周辺分布の推定方法として「帯域分割ケプストラム法」を提案する。本方法はStoicaらによるケプストラム法\cite{stoica}をペリオドグラムの特徴に合わ せて、閾値を適応的に決定する方法である。コンピュータシミュレーションによって本手法の優位性、特にスペクトルピークの推定に改善が見られた。
  • EEG Analysis in Wakefulness Maintenance State against Sleepiness by Instantaneous Equivalent Bandwidths  [Not invited]
    吉田 久
    29th IEEE EMBS Annual International Conference  2007/11  Lyon, France  29th IEEE EMBS Annual International Conference
     
    This paper proposes a new method for analyzing brain activity from Electroencephalogram (EEG) based on a concept of instantaneous equivalent bandwidths (IEBWs). The essence of the method using the IEBW is to track bandwidths changes of EEG signals. Copula-based time-frequency distributions have been adopted and we have also modified the construction method suitable for non-stationary random signals. The method was applied to EEG analysis in the wakefulness maintenance state against sleepiness. In our present study, sporadic synchronization was shown in the EEG signals while the subjects were trying to maintain wakefulness against sleepiness. That is, synchronization and desynchronization seem to succeed each other in the period. The results imply that the proposed method can track the EBWs change of EEG signals.
  • Independent Conponent Analysis by Renyi's Mutual Information  [Not invited]
    吉田 久
    電子情報通信学会2007年総合大会  2007/03  愛知県名古屋市(名城大学、天白キャンパス)  電子情報通信学会2007年総合大会
     
    回転混合さらた確率変数X,YのICAにおいて、理想的な条件下では、汎用尺度としての周辺分布のシャノンエントロピーの和 H(X)+H(Y) を超えるものはない。しかし、実際には問題に応じた効率的な尺度があっても良いと考え、Renyiエントロピーに基づくRange尺度とPeak尺度をここでは提案する。
  • EEG Analysis in the Wakefulness Maintenance State  [Not invited]
    吉田 久
    電子情報通信学会2007年総合大会  2007/03  愛知県名古屋市(名城大学、天白キャンパス）  電子情報通信学会2007年総合大会
     
    睡眠脳波に比べ、覚醒維持を課した状態における脳波の解析例はあまり多くなく、著者の知る限り覚醒維持状態における血流解析がわずかに見られる程度である。本研究では、覚醒維持を課した状態の脳波の時間ー周波数解析を行うことによって、眠気に逆らい覚醒を維持しようとする際の生理学的知見を得ようとするものである。被験者には覚醒を維持するように指示した後、座位開眼で読書(洋書)をしてもらい眠気を誘発するようにし、この間の脳波を測定する実験を行った。実験中のビデオ撮影映像から、眠気を誘発していると思われる付近の脳波を切り出し、解析を行った。
  • 各種分割点総当り画像2値化法の比較  [Not invited]
    吉田 久
    平成18年電気関係学会関西支部連合大会  2006/11  大阪府枚方市(大阪工業大学、枚方キャンパス)  平成18年電気関係学会関西支部連合大会
     
    画像2値化のための方法として、まず分布推定をしたのち、閾値を決定するという2段階法を提案する。このとき、分布推定および閾値推定のための評価関数として相互情報量を使うことを提案し、その優位性をコンピュータシミュレーションによって示した。また、2値化画像の評価においても、一致率ではなく相互情報量を用いることの優位性を示した。
  • Wigner-Ville分布による狭帯域過程の包絡線(時間周辺分布）の推定  [Not invited]
    吉田 久
    平成18年電気関係学会関西支部連合大会  2006/11  大阪府枚方市(大阪工業大学、枚方キャンパス)  平成18年電気関係学会関西支部連合大会
     
    確率過程の時間-周波数表現においては周辺分布の推定が重要である。著者らはすでにAM型の信号に対し、Winger-Ville分布を用いた新しい時間周辺分布の推定法を提案している。本報告では、搬 送波周波数が一定のAM被変調信号を考え、その時間周辺分布(包絡線)推定精度についてシミュレーションにより本方法の優位性を示した。
  • Marginal Estimation in Copula-based Time-Frequency Analysis of a Random Signal  [Not invited]
    吉田 久
    Fifth International Workshop on Information Optics (WIO-06)  2006/06  Toledo, Spain  Fifth International Workshop on Information Optics (WIO-06)
     
    確率過程における時間ー周波数表現においては、周辺分布の推定が重要な問題である。本稿ではWigner-Ville分布を用いた新しい時間周辺分布(確率過程における包絡線）の推定法を提案した。
  • 小川浩良; 高木淳; 八名和夫; 吉田 久
    第45回日本生体医工学会大会  2006/05  福岡国際会議場  第45回日本生体医工学会大会
     
    心拍変動のスペクトル解析が自律神経系の活動状態を無侵襲的に推定する方法として広く用いられている。これまではLF,HFなどの帯域パワーやスペクトルの傾きなどが解析の指標として用いられてきたが、本稿ではスペクトルパターンを区別する指標としてエントロピー帯域幅を導入し、その特性について論じた。
  • コンピュータシミュレーションによるNGL獲得構造NNの学習能力に関する比較  [Not invited]
    吉田 久
    2006年電子情報通信学会大会  2006/03  帝京大学(東京)  2006年電子情報通信学会大会
     
    ニューロジェネティック・ラーニング(NGL)は、ニューラル・ネットワーク(NN)の 構造決定と初期ウェイト獲得を遺伝的アルゴリズム(GA)を用いて同時に行う モデルとして、Kitanoによって提唱されている。 筆者らは、比較的複雑な問題として4ビットのパリティ問題を取り上げ、 NGL法によって得られた構造を持つNNの学習能力に関して、3層パーセプトロン、 および中間層内の層構造を仮定しない一般化全結合型パーセプトロンを 比較対象として、コンピュータシミュレーションを行ったので、その結果に ついて報告した。
  • 画像濃度分布推定のための混合モデル分布の比較  [Not invited]
    吉川 昭; 吉田 久
    平成16年度電気関係学会関西支部連合大会  2004/11  大阪  平成16年度電気関係学会関西支部連合大会
     
    画像濃度分布推定のためのモデル分布としてよく使われる混合正規分布モデルと、Palらが提案するPoisson混合モデルを定量的に比較するとともに、Poisson-Gauss混合モデルに関しても比較検討した。
  • Entropy Estimation by spacings and Image classfication  [Not invited]
    吉田 久; 吉川 昭; 宇崎周作; 藤井照也; 杉
    平成15 年電気関係学会関西支部連合大会（大阪）  2003/11  平成15 年電気関係学会関西支部連合大会（大阪）
     
    Spacings を使ったShannon エントロピーの推定法及び、Burg のエントリピーやダイバージェンスの推定とそれによる画像分類法を提案した。
  • Optimum thvesholding by maximum mutual information cviferion  [Not invited]
    吉川 昭; 増本哲也; 吉田 久
    電気関係学会関西支部連合大会（奈良）  2003/11  電気関係学会関西支部連合大会（奈良）
     
    画像閾値決定基準として従来使われている、最小偏り率基準より強力な基準として、最大相互情報量基準を提案し、その効果を確めた。
  • A Practical algorithm for detecting O-ring burrs  [Not invited]
    吉田 久; 吉川 昭; 宇崎周作; 藤井照也; 杉
    2003年電子情報通信学会総合大会（仙台）  2003/03  2003年電子情報通信学会総合大会（仙台）
     
    オイルシールなどに使われるO-ringのバリや歪みを検出する実用的なアルゴリズムを提案する。自動車やロケットにおいては、O-ringの品質管理は非常に重要である。
  • Application of Information Theoretic Divergence in Analysis of Fluctuations  [Not invited]
    吉田 久; 吉川 昭
    第17回ゆらぎ現象研究会（仙台）  2002/11  第17回ゆらぎ現象研究会（仙台）
     
    ゆらぎ信号の自動帯域分割や不等間隔サンプリング、画像の2値化、多値化などの応用例を最小ダイバージェンス原理を用いて示すとともにDynamic Programming（DP）法が実際の計算上で重要な役割を果たすことを示した。
  • A fast algorithm for adaptive partitionning distributions and its application to multithresholding  [Not invited]
    吉川 昭; 矢井田兼; 吉田 久
    平成14年度電気関係学会関西支部連合大会（東大阪）  2002/11  平成14年度電気関係学会関西支部連合大会（東大阪）
     
    画像濃度ヒストグラムの分割の高速アルゴリズム（DP法）とそれを用いた画像複数閾値の決定について述べ、情報圧縮実験結果を示した。
  • An estimation method of a periodogram by non equ interval smoothing  [Not invited]
    吉川 昭; 内田英二; 矢井田兼; 吉田 久
    平成14年度電気関係学会関西支部連合大会（東大阪）  2002/11  平成14年度電気関係学会関西支部連合大会（東大阪）
     
    情報論的ダイバージェンスを用いたペリオドグラムの不等間隔平滑化推定法を提案した。
  • Generalized equivalent baudwidth defined by using Renyi’s entropy and its estimation  [Not invited]
    吉田 久; 吉川 昭
    The International Society for Optical Engineering（アメリカ）  2002/07  The International Society for Optical Engineering（アメリカ）
     
    レニーエントロピーを用いて、一般化等価帯域幅を導くとともにその推定値に対する性質をエントロピーパワー不等式から導いた。
  • Generalized equaialent bandwidth defined by using Renyi’s entropy and its application to EEG analysis  [Not invited]
    吉田 久; 吉川 昭
    ⅣInternational workshop on biosignal interpretation（イタリア）  2002/06  ⅣInternational workshop on biosignal interpretation（イタリア）
     
    確率過程の等価帯域幅をレニーエントロピーを用いて一般化した表現を与えた。また、この一般化等価帯域幅を用いて、脳波解析した例についても述べた。
  • A New class of equioalent bandwidth and its application to bio-signals  [Not invited]
    吉田 久; 吉川 昭
    The 2001 International Technical Conference on Corcuits/Systems, Computers and Communications  2001/07  Tokushima, JAPAN  The 2001 International Technical Conference on Corcuits/Systems, Computers and Communications
     
    Rinyi のα一次エントロピーを用いることにより、 従来から提案されている重要な確率過程等価帯域幅を含む広いクラスを構成することができることを示した。 また、 それを用いて脳波解析を試みた。
  • Equivalent Bandwidth of order α and its application to EEG analysis  [Not invited]
    吉田 久; 吉川 昭; 田中啓文; 海沼敏
    2001 年電子情報通信学会総合大会 (草津)  2001/03  2001 年電子情報通信学会総合大会 (草津)
     
    確率過程の等価帯域幅を定義し､ この等価帯域幅を脳波解析へ応用した｡ その結果､ 脳波の同期､ 非同期現象を解析するのに役立つことが示された｡
  • Equivalent bandwidth of a random process and Renyi's entropy  [Not invited]
    吉川 昭; 吉田 久
    2001 年電子情報通信学会総合大会  2001/03  2001 年電子情報通信学会総合大会
     
    確率過程の等価帯域幅は一通りでなく､ いまだ統一的概念が成立していなかった｡ 本報告では､ 従来から提案されているいくつかの代表的等価帯域幅が Renyi の 2 次エントロピーで統一的に表現できることを示した｡

Works

  • 知的クラスター創成事業「Human L-Cube Cluster」 サブテーマ：「医療用スマートデバイス＆システムの研究開発と事業化」
    2005 -2006
  • 分子レベルでの神経細胞膜の挙動観察とそれに基づく新規な神経モデルの構築
    2004
  • 生体信号の統計情報解析と時間－周波数解析
    2003
  • 情報論的ダイバージェンスによる各種新しい信号・画像解析法の提案
    2002
  • 時間ー周波数解析における局所的特徴量の理論と精神的負荷状態変化の追跡
    1999 -2001
  • 和歌山県傾斜地における局所的気候値と気象条件の解析と推定
    2000
  • ニューラルネットワーク技術による外観自動検査装置の開発
    1999
  • 確率場及び多次元多変量時系列の特徴付けのための大域的相関分析法とその応用
    1996 -1998

MISC

Industrial Property Rights

  • Hiroshi Kobayashi, Toshiyuki Sado, Hisashi Yoshida  Nara Medical University, Kindai University  201403088475261860
  • 特許AU2012210045B2:Fetal heart potential signal extraction program, fetal heart potential signal-discriminating apparatus and pregnancy monitoring system using same  
    Hiroshi Kobayashi, Toshiyuki Sado, Hisashi Yoshida  Nara Medical University, Kindai University
  • 特開EP2668897A4:FETAL HEART POTENTIAL SIGNAL EXTRACTION PROGRAM, FETAL HEART POTENTIAL SIGNAL-DISCRIMINATING APPARATUS AND PREGNANCY MONITORING SYSTEM USING SAME  2015/04/22
    Hiroshi Kobayashi, Toshiyuki Sado, Hisashi Yoshida  Nara Medical University, Kindai University
  • 特許US 8,897,862 B2:Fetal cardiac potential signal extraction program, fetal cardiac potential signal discriminating apparatus, and pregnancy monitoring system using the same    2014/11/25
    KOBAYASHI Hiroshi, SADO Toshiyuki, YOSHIDA Hisashi
  • 吉田 久, 平尾 佳彦, 八木 良樹  マイクロニクス株式会社  201303072241845639

Awards & Honors

  • 2011/05 The Institute of Image Information and Television Engineers Niwa-Takayanagi Awards
     A Statistical Analysis of Attentional Effects on Drift Eye Movements 
    受賞者: KOHAMA Takeshi;YOSHIDA Hisashi;TAKENAKA Haruka;TODA Naohiro

Research Grants & Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2023/04 -2026/03 
    Author : Hisashi Yoshida; Takeshi Kohama
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2021/04 -2024/03 
    Author : 小濱 剛; 吉田 久
     
    本研究では，注意統制課題遂行中のfNIRS信号と固視微動の解析に基づいて，持続的注意に関与する情報処理過程を客観的に捉える手法を開発し，認知機能リハビリテーションへの応用を検討することを目的とする．そのための基礎研究として，2種類のキューを持つ周辺ターゲット検出課題による注意統制実験を実施する．モニタ中央の注視視標が一定時間の後に赤か青の＋か×に切り替わる．その後，予め左右に提示されたボックスの一方が45度傾斜し，最後に左右いずれかのボックス内にターゲットが提示される．このような視覚刺激に対し，「注意維持課題」と「注意割込課題」の2条件を設ける．「注意維持課題」では，被験者に注視視標が赤の＋か青の×であれば右，その逆の組み合わせで左にターゲットが提示されることを予め教示し，注視視標の意味する方向に能動的に注意を向けさせる．「注意割込課題」では，注視視標の意味を解釈せずにターゲットを検出するよう教示し，傾きが変化するボックスに対して注意を誘導する．いずれの条件も，被験者が受け取る視覚情報は完全に一致することから，本課題により，意図的に注意を維持する場合と，突発的に注意が奪われた場合との直接的な比較が可能となる．
    令和3年度は，先述した課題に対して fNIRS 計測を行い，注意機能の定量的評価指標としての妥当性を検討した．健常被験者を対象にして，実験遂行中のfNIRS信号を解析し，全被験者で各課題に寄与した脳領域を集計した．その結果，計測対象とした右脳において，上前頭回，上頭頂小葉といった注意の統制に関与する領域の活動が確認された．このうち，「注意維持課題」では適切な注意の配置や持続的注意に寄与する中前頭回が，「注意割込課題」ではボトムアップ注意に強く寄与する角回が特異的に応答していることが示されたことから，fNIRS に基づく注意機能のモニタリングが可能であることが示唆された．
  • Japan Society for the Promotion of Science：Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2018/04 -2021/03 
    Author : YOSHIDA Hisashi
  • 日本学術振興会：科学研究費助成事業 基盤研究(C)
    Date (from‐to) : 2017/04 -2020/03 
    Author : 小濱 剛
  • Japan Society for the Promotion of Science：Grant-in-Aid for Scientific Research(C)
    Date (from‐to) : 2017/04 -2020/03 
    Author : 加藤 天美
  • 在宅妊婦見守りシステムの開発
    Ministry of Internal Affairs and Communications：Strategic Information and Communications R&D Promotion Programme
    Date (from‐to) : 2016/04 -2018/03 
    Author : YOSHIDA Masaki
  • Japan Society for the Promotion of Science：Grant-in-Aid for Scientific Research(C)
    Date (from‐to) : 2014/04 -2017/03 
    Author : KOHAMA Takeshi
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2015 -2017 
    Author : YOSHIDA HIISASHI
     
    In this study, we developed a method for removing or separation of additive and convolutive artifacts artifact from multi-dimensional biosignals with independent vector analysis. We applied the method to extract fetal electrocardiogram from maternal abdomen as a test of our proposed method. As a results, the proposed method showed better performance rather than the conventional independent component analysis method. In addition, we developed a method for estimating a distribution of fetal cardiac potential which was observed on the maternal abdomen. The distributions are of help in order to find electrodes’ coordination which has better performance on the maternal abdomen.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2012/04 -2015/03 
    Author : YONEZAWA Yasushige; KIKUGAWA Gouta; FUJISAWA Masao; YOSHIDA Hisashi; TACHIBANA Hideki; AKASAKA Kazuyuki
     
    We have applied our extended ensemble simulation, MCMD-METAD hybrid method to the several typical issues of protein simulations. Our method has a remarkable advantages against old similar methods, providing clear convergence property. We implemented the method to our molecular dynamics simulation program. Moreover, we then developed a novel long-range potential which significantly accelerates simulations. We implemented it to our simulation program, evaluating properties of several bio-systems. As a results, we found that the search ability of taboo like method, such as METAD, is strongly depend on the pre-determined reaction coordinate. This suggests the good reaction coordinate determination is of paramount importance for protein simulation studies.
  • Japan Society for the Promotion of Science：Grant-in-Aid for Scientific Research(C)
    Date (from‐to) : 2012/04 -2015/03 
    Author : YOSHIDA Hisashi
     
    本研究の目的は、従来知見のほとんどない「眠気に逆らい覚醒維持の努力をしている状態の脳・生理機能の解析をするために、近赤外光を利用した光イメージング計測と各種多次元生体電気計測の同時計測技術を実現させ、特に光イメージングと脳波計測における互いの長所を活かす統合的な計測技術の確立とその解析法に関する研究を行うことである。昨年度我々は、光イメージングの近赤外線スペクトロスコピー（Near-Infrared Spectroscopy：NIRS）信号を解析するための前処理として，脳活動に関連するヘモグロビン変化量とそれ以外の要因に起因するヘモグロビン変化量を分離する方法を開発した。これはBOLD効果をモデル化し脳機能成分と全身性成分に分離する方法と、独立成分分析法を用いてアーチファクト成分を除去する方法を組み合わせることによって、脳機能成分を抽出する方法である。 平成25年度は，視覚注意の集中が眼球運動に与える影響の評価によって、覚醒維持に寄与しうる視覚刺激パターンの性質に対する知見を得つつある状況を利用して，従来からの実験に加えて、課題非依存性思考状態が，認知パフォーマンスに与える影響の客観的な評価を目的に，光イメージングによる脳活動を記録する実験を行い，目標探索時間や前頭前野外側部のNIRS信号を解析した。実験の結果，複数の視覚属性の組み合わせにより定義された視対象の中から唯一の特徴を持った目標を探索する場合においてのみ，課題非依存性思考の有無により目標探索時間が影響されることが示された．また，この条件において，NIRS 信号から推定された前頭前野外側部の賦活度が高まることも示唆された．これらのことから，課題非依存性思考によって前頭前野の情報処理リソースが消費されることが示唆され，こうした状況下では，認知タスクのパフォーマンスが影響を受ける可能性が示された
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2013 -2015 
    Author : KIKKAWA Sho; YOSHIDA Hisashi; NAKASAKO Noboru; KOHAMA Takeshi
     
    (1) We introduced L and U filters having not been well-known as morphological filters and the digital pulse transform (DPT) constructed of L and U filters. (2) We proposed a new method for detecting randomly generated signals buried in noise, in particular, a new method to detect saccades in human eye movement data. We attained error-free detection of the saccades by this method which has not been achieved by traditional linear filters. This method can be widely applied to detection problems in biomedical environmental data processing. (3) Agaist the commomly accepted theory that median filtering outperforms traditional linear filtering in preserving signal edges while reducing noise, we theoretically proved that moving average filter is a better smoother preserving signal edges than the median filter under a practical wide range condition.
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2010 -2013 
    Author : Takeshi KOHAMA; Hisashi YOSHIDA
     
    The purpose of this study is to evaluate the influence of ``undetectable motions'', the motion information under the perception threshold, on cognitive functions by statistical analyses of the property of fixation eye movements. Subjects performed rapid serial visual presentation (RSVP) tasks with undetectable or ambiguous motions in the background while maintaining their fixation. We evaluated the influence of these motions on top-down attention mechanism by analyzing fixation eye movements. The results suggest that microsaccade rates were correlated with subliminal motion information, and fluctuations of drift eye movements were modulated by low-contrast motions in the peripheral vision.
  • 母体生体信号計測による胎児心電図測定法の開発
    Japan Science and Technology Agency：Adaptable and Seamless Technolog trasfer Program through targetdriven R&D
    Date (from‐to) : 2011/03 -2012/04 
    Author : YOSHIDA Hisashi
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2008 -2011 
    Author : Hisashi YOSHIDA; Takeshi KOHAMA
     
    We have measured multi-channel bio-signals, i. e., electroencephalogram, heart rate variability, blood pressure, eye movement and pupil diameter variability in order to evaluate the influence of visual stimuli to the wakefulness maintenance state against sleepiness. We performed time-frequency analysis, conventional spectral analysis, and feedback modeling to those signals. All results showed that physiological activities in wakefulness maintenance state have different features from those in onset of natural sleep. In addition, we have introduced new artifact removal methods to the EEG analysis.
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2007 -2010 
    Author : Sho KIKKAWA; 橋本 周司; Hisashi YOSHIDA; Noboru NAKASAKO; Shuji HASHIMOTO
     
    (1) We proposed a new mutual information criterion for deciding an optimal mixture distribution and an optimal threshold. (2) We proposed the usage of Renyi's alpha-entropy as a measure of width of marginal distribution and obtained very intuitive new and simple ICA methods. (3) We proposed an adaptive method for smoothing the periodogram for positive time-frequency representation. For impulse train time-frequency analysis, we proposed an inverse domain demodulation method of IPFM and an objective evaluation method for demodulators. Further, we proposed distance estimation method exploiting time-frequency feature of reflected signal from a moving object.
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2005 -2007 
    Author : Hisashi YOSHIDA
     
    The objectives of the project are :1. To present a new class of generalized equivalent bandwidths▲(EBWs) of stationary random signals by using Renyi divergence including a spectral flatness measure,2. To define a new class of instantaneous equivalent bandwidths▲(IEBWs) for non-stationary random signals and obtain its estimation method,3. Application of the proposed methods, i.e. EBWs and IEBWs, to bio-signals.The results of the project are listed as follows.1. We have obtained a unified presentation of EBWs of random signals including spectral flatness measure which are well known in the field of speech processing introducing Renyi divergence2. We have proposed a new class of IEBWs for non-stationary random signals. IEBWs are defined on a positive time-frequency distribution based on Copula theory which is developed in statistics.3. We have developed the method for estimating frequency and time marginal of time-frequency distributions of non-stationary random signals.4. We have applied to the IEBW to EEG analysis. As a result, the proposed method can track the change of the bandwidth of the EEG signals in the periods between wakefulness state and wakefulness maintenance state against sleepiness. The EEG signal in the period of wakefulness maintenance state against sleepiness has wide bandwidth since it has high frequency components. The result is very interesting to understand a relationship between the prefrontal cortex which is a main area of activity and hypothalamus which controls sleep and wakefulness.
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2003 -2006 
    Author : Sho KIKKAWA; Hisashi YOSHIDA
     
    1. We proposed a unified class of equivalent bandwidths of a random process by using Renyi's a-order entropy. It is useful to evaluate randomness of a random process.2. We investigated global thresholding of a image. In addition to traditional one-step methods, we proposed a new idea of the two-steps method. In the first step of the method, you estimate the optimum model probability distribution that the grey-level variable obeys and in the second step you decide the optimum threshold to binarize the image. We propose a new binarization-oriented method for model distriobution fitting where we introduce class labels as hiden-variable and, instead of the traditional divergence measure, information theoretic mutual information measure is used. Simulation experiments shows our methodes are very powerful.
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 1999 -2002 
    Author : Sho KIKKAWA; Hisashi YOSHIDA
     
    The state of mental stress is often measured and estimated by using EEG and/or ECG. Since feature of these signals and the mental state change with time, we have to deal them as non-stationary data. Therefore we have to develop effective methods for non-stationary data analysis.The theory of time-frequency analysis is known as a powerful tool to analyze non-stationary signals like biomedical signals.In this project, we tried to find effective parameters by which we can extract essential characteristics of a random process and analyze and interpret the non-stationary signals. In the theory of random processes, many kind of effective bandwidths have been proposed and used very often in may branches. How ever there have been few effort to unity them. We proposed a general class of infinite effective bandwidths which includes all the essential traditional bandwidths. The class is defined by Renyi's alpha-order entropy and gives unified expression of the bandwidths. We call them alpha-order bandwidths, W-alpha. The concept of W-alpha is easily expand to non-stationary analysis. Then we proposed time varying W-alpha based of time-frequency distributions and showed that the time varying W-alpha is effective by simulation analysis. We applied them to EEG analysis measured from persons who are put mental stress by been a task of Uchida-Kraepelin. We showed the method is useful to track alpha-bandwidth of EEG.Meteorological conditions are essential factors which affect human mental state. In the late stage of this project, we began to develop methods to analyze meteorological data, that is, image data from some meteorological satellites, temperature data, rainfall data, etc. We tried apply information theoretical concepts, like entropy and divergence to our methods. We have been showing these information theoretical concepts are very powerful to our purpose.
  • 文部科学省：科学研究費補助金(奨励研究(A))
    Date (from‐to) : 1999 -2000 
    Author : 吉田 久
     
    瞬時周波数f_i(t)は解析信号z(t)の位相角の微分としてf_i(t)=1/(2π)d/(dt)[argz(t)]で定義される.しかし、定義式による推定法は一般に雑音に弱いと考えられる.そこで、昨年度は実信号x(t)の解析信号z(t)を求め,その解析信号z(t)の時間一周波数分布から瞬時周波数と瞬時帯域幅を推定するシミュレーションを行った。その結果、解析信号z(t)に変換するためのHilbert変換の性質から,有限長の信号を離散化するという操作のために、連続信号には表れない性質が離散信号に表れることを明らかにした。本年度は、瞬時周波数ではなく、瞬時帯域幅に関する研究に焦点を絞って理論的に検討した。瞬時帯域幅は比較的よく研究されている瞬時周波数に比べ、まだ詳しく研究されているとは言えない。瞬時周波数は一般的に、時間-周波数分布の分散と考えるのが普通であるが、狭帯域信号の場合はどうするかなど問題点も多い。そこで、情報理論的な視点から、まず確率過程のα次等価帯域幅を定義した。これは、Renyiのαエントロピーから導かれるもので、これまでに提案されている重要な帯域幅の定義を含むような一般的な確率過程の等価帯域幅のクラスを定義するものである。現在のところ、心音のように非定常な信号における瞬時帯域幅を推定できる段階ではないが、今後の研究には期待が持てる。
  • 情報論的ダイバージェンスを用いた画像処理
    Date (from‐to) : 2000
  • 確率過程の等価帯域幅に関する研究
    Date (from‐to) : 1999
  • Research in Equivalent Bandwidths for Stochastic Processes.
    Date (from‐to) : 1999
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 1996 -1998 
    Author : Sho KIKKAWA; Hisashi YOSHIDA
     
    (a)We defined statistical numbers of degrees of freedom (NDF) as an equivalent uncorrelated number of points per unit area in a 2-dimensional random field.(b)The first order NDF is equal to Fisher's information about the first statistical moment. The second order NDF is an approximation of Fisher's information about the second moment.(c)Many interesting features of a random field and a random process were deduced from the NDF's. They are correlation time, correlation length, correlation area, line-correlation, area-correlation, and bundle-correlation.(d)The mutual information and the vector correlation coefficient between two random processes are useful to measure how they are globally correlated. Relationship between mutual information and vector correlation were investigated both theoretically and numerically.(e)The results obtalned above were applied to annualizing some meteorological data and biomedical data.
  • 文部科学省：科学研究費補助金(奨励研究(A))
    Date (from‐to) : 1996 -1996 
    Author : 吉田 久
     
    ヒトの眼における瞳孔径はカメラの絞りと同様に対象物を明瞭に見るために重要な役割を果たしているが、カメラとは異なり絶えず変動している。本研究は、この変動を不要な雑音として捉えるのではなく、その原因を自律神経系の活動に見い出し、瞳孔径変動から無侵襲にその活動を推定しようとするものである。筆者はこれまでに瞳孔径変動が自律神経の影響を強く受けていることを明らかにしており、近年社会問題として大きく取り上げられている自律神経失調疾患に対して新たな無侵襲的診断手法を提供する可能性もあり、その社会的意義は極めて大きいと思われる。また、同様の目的で盛んに研究されている心拍変動との関連を調べることにより両者の詳細な性質をより把握できるものと考えている。以上の目的を達成するために本年度は、これまでの実験で得られたデータを解析するための新たな非線形解析法を開発した。これまでに筆者らは最適線形系の出力誤差パワーに着目した非線形度を定義し、ニューラルネットを用いた推定法を提案している。この手法の場合、対象とするシステムの完全な同定が必要となるが、実際には完全な非線形モデルの構築、システム同定が可能とは限らない。そこで、非線形度推定に用いる非線形システムモデルを条件とした条件付きシステム非線形度を定義し、その上界として先に提案した非線形度を位置づける事とした。今後、多変数に応用できるよう非線形モデルを拡張すること、またこれらの解析法を用いて瞳孔径と心拍変動の関連を明らかにするとともに、その生理学的な意味付けを行うことが今後の課題である。
  • ニューラルネットワークを用いたパターン認識
  • 時間-周波数解析の生体信号への応用
  • ニューラルシステムの状態推定
  • Neural Networks for Pattern Recognition
  • Time-Frequency Analysis of Biological Signals

Committee Membership

  • 2023/06 - Today   The Institute of Electronics, Information and Communication Engineers   Technical Committees, ME and Bio Cybernetics, Chair
  • 2020/04 - Today   The Institute of Electronics, Information and Communication Engineers   Young Researcher's Award Committee
  • 2020/04 - Today   Japanese Society for Medical and Biological Engineering   "New Development Award" Selection Committee
  • 2017/04 - Today   Japanese Society for Medical and Biological Engineering, Kansai Branch   Secretary
  • 2017/04 - Today   Japanese Society for Medical and Biological Engineering   Delegates
  • 2002/04 - Today   Japanese Society for Medical and Biological Engineering   Special Interest Group of JSMBE: Biosignal Measurements and Interpretations
  • 2022/10 -2023/09   Information Processing Society of Japan / The Institute of Electronics, Information and Communication Engineers   FIT Technical Committee
  • 2022/06 -2023/05   The Institute of Electronics, Information and Communication Engineers   Technical Committees, ME and Bio Cybernetics, Vice chair
  • 2020/07 -2022/06   Japan Society for the Promotion of Science   Committee for the Selection of Special Research Fellows
  • 2018/04 -2022/03   Japanese Society for Medical and Biological Engineering   "Best Paper Award / Sakamoto Award" selection committee
  • 2006/01 -2015/12   International Conference IEEE Engineering in Medicine and Biology society   Associate Editor of Biomedical Signal Processing
  • 2013/01 -2013/12   52th Conference of Japanese Society for Medical and Biological Engineering   Organizing Committee
  • 2009/01 -2009/12   Biosignal Interpretation 2009   Scientific Committee
  • 2007/01 -2007/12   Noise and Fluctuations in Photonics, Quantum Optics, and Communications in SPIE   Program Committee
  • 2006/01 -2006/12   Fifth International Workshop on Information Optics (WIO-06)   Program Committee

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