Yasuhiko Jimbo

The University of Tokyo, 白山, Tōkyō, Japan

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Publications (58)53.48 Total impact

  • T Numata · Y Ogawa · K Kotani · Y Jimbo
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    ABSTRACT: Background: Evaluating the accurate responses of the cardiovascular system to external stimuli is important for a deeper understanding of cardiovascular homeostasis. However, the responses should be distorted by the conventional time domain analysis when a frequency of the effect of external stimuli matches that of intrinsic fluctuations. Objectives: The purpose of this study is to propose a mixed signal processing of time domain and respiratory phase domain to extract the response waveforms of heartbeat and blood pressure (BP) to external stimuli and to clarify the physiological mechanisms of swallowing effects on the cardiovascular system. Methods: Measurements were conducted on 12 healthy humans in the sitting and standing positions, with each subject requested to swallow every 30 s between expiration and inspiration. Waveforms of respiratory sinus arrhythmia (RSA) and respiratory-related BP variations were extracted as functions of the respiratory phase. Then, respiratory effects were subtracted from response waveforms with reference to the respiratory phase in the time domain. Results: As a result, swallowing induced tachycardia, which peaked within 3 s and recovered within 8 s. Tachycardia was greater in the sitting position than during standing. Furthermore, systolic BP and pulse pressure immediately decreased and diastolic BP increased coincident with the occurrence of tachycardia. Subsequently, systolic BP and pulse pressure recovered faster than the R-R interval. Conclusions: We conclude that swallowing-induced tachycardia arises largely from the decrease of vagal activity and the baroreflex would yield fast oscillatory responses in recovery.
    No preview · Article · Nov 2014 · Methods of Information in Medicine
  • Y. Takayama · T. Suzuki · K. Mabuchi · Y. Jimbo
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    ABSTRACT: Understanding and control of functional roles in the central nervous systems are important themes in the field of neuroscience and neuroengineering. In particular, development of recording and analysis methods for neuronal networks which consist of enormous numbers of neurons has been major challenge. We have carried out recording and regulation of networks of cortical neurons reconstructed in vitro using microfabrication techniques, in order to figure out the developmental changes in neuronal networks. Here, we attempt to introduce our recent experiments and results: 1) Characterization of self-organization processes in cultured cortical networks during development, 2) Evaluation and control of stem cell-derived neuronal networks and 3) Development of artificial cultured neuronal networks in structures and functions using microfabrication and microfluidics techniques. © 2014, Japan Soc. of Med. Electronics and Biol. Engineering. All rights reserved.
    No preview · Article · Aug 2014 · Transactions of Japanese Society for Medical and Biological Engineering

  • No preview · Article · Jan 2013 · Transactions of Japanese Society for Medical and Biological Engineering
  • T. Maruyama · S. Suzuki · L. Yoshida · K. Kotani · Y. Jimbo
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    ABSTRACT: A novel co-culture device of neuronal cells was developed for analysis of cell interaction between a normal cell and an Alzheimer's disease infected cell. The device consisted of co-culture chamber system and a microelectrode arrays(MEA). The chamber system has a central chamber and three peripheral compartment chambers, connected by micro-channels. Rat hippocampal neurons were cultured separately in each of the peripheral compartment chamber. Neurites of the hippocampal neurons grow through the micro-channels to reach the central chamber and make connection. Formation of synaptic junction of the neuritis was confirmed by the imuunohistochemical staining. Electrical activities generated by hippocampal neurons network were recorded by the MEA, placed on the bottom of the three compartments. The results demonstrated the capability of this device for the analysis of pathogenic mechanism of Alzheimer's disease.
    No preview · Conference Paper · Jan 2013
  • A. Saito · Y. Takayama · Y. Jimbo

    No preview · Article · Jan 2013 · Transactions of Japanese Society for Medical and Biological Engineering
  • Hirokazu Takahashi · Yasuhiko Jimbo
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    ABSTRACT: The Moore's law predicting that the number of transistors on integrated circuits doubles every 18 months since 1970's has been underlying industrial innovation. In the field of neuroscience, a similar trend is observed for the number of simultaneously recorded neuronal cells, which has doubled every 7.4 years since the late 1950's. Neural engineering has emerged from the confluence of these two technological trends and has significantly promoted a number of progresses in our understanding of the brain and the developments of neural prosthesis. In the present paper, we introduce how innovative instrumentation engineering and information technologies have brought benefits in our daily physiological experiments and sometimes led to major discoveries in a discontinuous manner. Furthermore, increasing capacity to acquire and analyze massive data may change not only treatments of neural data, but also scientific approaches in neuroscience.
    No preview · Article · Jan 2013 · IEEJ Transactions on Electronics Information and Systems
  • K. Shimba · K. Sakai · K. Arimatsu · K. Kotani · Y. Jimbo
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    ABSTRACT: The axon has a crucial role in the signal processing in the central nervous system. However, little is known about relationship between the structure of axons and conduction property of the axon. In this study, we developed a culture device to evaluate conduction velocity of relatively proximal (near the soma) and distal (far from the soma) parts of axons. The device has electrode units aligned at the bottom of the microtunnel structure. The electrode units enable the recording of action potentials of a single axon from three electrodes. Mouse cortical neurons were cultured in the device. The activity was recorded every five days. By employing an effective spike sorting method and a histogram method, propagating action potentials along the individual axon were successively detected from the spike trains which included the bursting activity. Finally, the change of the conduction delay at the distal part of axons was evaluated. The results show that our experimental system is feasible to study the conduction property of the axon.
    No preview · Conference Paper · Jan 2013
  • Y. Ogawa · K. Kotani · Y. Jimbo
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    ABSTRACT: The WM (working memory) is the essential element of intellectual work, thus the estimation of fatigue from neural activations in the WM task is important to control the stress with intellectual work. Furthermore, these WM evaluations from neural activities are useful for an improvement of diagnosis of psychiatric disorders. In this study, we investigate the relationship with the hemodynamic changes measured with Near Infrared spectroscopy during the WM task and the WM performance. Furthermore, we show the difference of the hemodynamics in delay time between correct-tasks and incorrect-tasks.
    No preview · Conference Paper · Jan 2012
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    ABSTRACT: Finger Braille is one of the communication media of deafblind people. In one-handed Finger Braille, a sender dots the left part of the Braille code on the distal interphalangeal (DIP) joints of the index, middle and ring fingers of a receiver, and subsequently dots the right part of the Braille code on the proximal interphalangeal (PIP) joints of the same fingers. Because there is a small number of non-disabled people who are skilled in Finger Braille, deafblind people communicate in this medium only through an interpreter. In this study, we developed a Finger Braille recognition system using small piezoelectric accelerometers worn by the receiver. We first conducted a measurement experiment to derive algorithms for the recognition of the dotted fingers and positions. The results showed that the accuracy of the recognition of dotted fingers was 92.9%, and the recognition system was independent of the dotted strength, dotted position and receiver. The accuracy of the recognition of dotted positions was 81.9%, and the recognition system could recognize dotted positions if the receiver's hand formed a natural longitudinal arch on the desk. Next, an evaluation experiment was carried out. The results showed that the accuracy of the recognition of dotted fingers by dotting was 89.7%, and the accuracy of recognition of dotted positions by dotting was 92.3%. Therefore, the recognition system could recognize sentences accurately when the interpreter dotted clearly.
    No preview · Article · Jan 2010 · Journal of Biomechanical Science and Engineering
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    ABSTRACT: Light addressing is an emerging and sophisticated technique that can induce pinpoint and/or patterned neuronal activation in cultured neurons. We previously developed a light-addressable electrode using hydrogenated amorphous silicon (a-Si:H), which was sandwiched between a tin oxide (SnO(2)) substrate and a passivation layer of zinc antimonate (ZnOSb(2)O(5)) dispersed epoxy. This research developed an experimental system that simultaneously implemented light-addressed stimulation and Ca(2+) imaging of neuronal activities. The translucent and thin laminated structure of our electrode permitted optical accesses from two directions: Ca(2+) imaging from above and light addressing from beneath. The submillisecond bright/dark switching property of our electrode offered light-addressed stimulation without causing interference with Ca(2+) imaging. To provide patterned illumination for light addressing, a digital micromirror device was installed in the system as an active photomask. The system could induce pinpoint neuronal activation at a cellular level.
    No preview · Article · Jul 2009 · IEEE transactions on bio-medical engineering
  • H. Moriguchi · M. Goto · Y. Jimbo · T. Torii
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    ABSTRACT: We have developed a parallel monitoring method of multicellular activity, which emerges in small groups of cells and reflect surrounding biochemical and physical conditions. In this study, small groups of neurons and glial cells are mass-produced by means of ink-jet printing, and the intracellular calcium level and the extracellular potential are simultaneously monitored with single-cell resolution. As the result, arrayed small neuronal networks showed spontaneous, rhythmic activity.
    No preview · Article · Jan 2009
  • Yasuhiko Jimbo
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    ABSTRACT: No abstract is available for this article.
    No preview · Article · Nov 2008 · IEEJ Transactions on Electrical and Electronic Engineering
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    ABSTRACT: Finger Braille is one of tactual communication media of deafblind people. Deafblind people who are skilled in Finger Braille can catch up with speech conversation and express various emotions. Because there are small non-disabled people who are skilled in Finger Braille, deafblind people communicate only with interpreters. Objective of this study is development of a Finger Braille supporting device which assists not only verbal communication but also non-verbal (emotional) communication between deafblind people and non-disabled people who are not skilled in Finger Braille. In this paper, to develop emotion recognition system, we analyzed features of emotional expression (Neutral, Joy, Sadness and Anger) and derived an algorithm of emotion recognition using accelerometers worn by receiver. According to the results of discriminant analysis, it was considered that emotion recognition using the discriminant functions by standardized data and the average of posterior probabilities in a sentence was possible and independent of sentences.
    No preview · Conference Paper · Sep 2008
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    ABSTRACT: Finger Braille is one of tactual communication media of deafblind people. In one-handed finger Braille, a sender dots the left part of Braille code on the DIP joints of index, middle and ring fingers of a receiver, and then the sender dots the right part of Braille code on the PIP joints of them. Then the receiver recognizes the Braille code. Deafblind people who are skilled in Finger Braille can catch up with speech conversation and express various emotions. Because there are small non-disabled people who are skilled in Finger Braille, deafblind people communicate only with interpreters. In this paper, we developed a finger Braille recognition system. And evaluation experiments of recognition of monosyllables and sentences were carried out. As the results of the evaluation experiment of recognition of monosyllables, the accuracy of recognition of dotted fingers was 92.9% and the recognition system was independent of dotted strength, dotted position and receiver. The accuracy of recognition of dotted positions was 81.9% and the recognition system could recognize dotted positions if the receiver's hand shaped a natural longitudinal arch on the desk. As the results of the evaluation experiment of recognition of sentences, the accuracy of recognition of dotted fingers by dotting was 89.7% and the accuracy of recognition of dotted positions by dotting was 92.3%. Therefore the recognition system could recognize the sentences accurately when the interpreter dotted clearly. And the receiver should re-set his/her hand on the desk when he/she noticed cut-down of accuracy of recognition.
    No preview · Conference Paper · Sep 2008
  • W Tonomura · H Moriguchi · Y Jimbo · S Konishi
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    ABSTRACT: This paper describes an advanced Micro Channel Array (MCA) so as to record neuronal network at multiple points simultaneously. Developed MCA is designed for neuronal network analysis which has been studied by co-authors using MEA (Micro Electrode Arrays) system. The MCA employs the principle of the extracellular recording. Presented MCA has the following advantages. First of all, the electrodes integrated around individual micro channels are electrically isolated for parallel multipoint recording. Sucking and clamping of cells through micro channels is expected to improve the cellular selectivity and S/N ratio. In this study, hippocampal neurons were cultured on the developed MCA. As a result, the spontaneous and evoked spike potential could be recorded by sucking and clamping the cells at multiple points. Herein, we describe the successful experimental results together with the design and fabrication of the advanced MCA toward on-chip analysis of neuronal network.
    No preview · Article · Feb 2008 · Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference
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    ABSTRACT: Finger Braille is one of tactual communication media of deafblind people. In two-handed Finger Braille, index finger, middle finger and ring finger of both hands are likened to keys of a Braille typewriter. A sender dots Braille code on the fingers of a receiver like whether he/she does the type of the Braille typewriter. Then the receiver recognizes the Braille code. In one-handed Finger Braille, the sender dots the left column of Braille code on the DIP joints of three fingers of the receiver, and then the sender dots the right column of Braille code on the PIP joints of them. Deafblind people who are skilled in Finger Braille can catch up with speech conversation and express various emotions. Because there are small nondisabled people who are skilled in Finger Braille, deafblind people communicate only with interpreters. Objective of this study is development of a Finger Braille supporting device which assists not only verbal communication but also nonverbal (emotional) communication between deafblind people and non-disabled people who are not skilled in Finger Braille. In this paper, an experiment of emotional expression of Finger Braille was carried out. And we analyzed features of emotional expression of Finger Braille and discussed algorithm of emotion recognition. The features of emotional expression were: (1) the durations of code of Joy were particularly shorter than other emotions; (2) the durations of code of Sadness were particularly longer than other emotions; (3) the finger loads of Anger were particularly bigger than other emotions. To develop emotion recognition system, we discussed algorithm of emotion recognition using the accelerometers worn by tester. According to the results of discriminant analysis, it was considered that emotion recognition using the discriminant functions and the average of posterior probabilities in a sentence was possible.
    No preview · Chapter · Dec 2007
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    Y Jimbo
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    ABSTRACT: Based on the advantages of MEA-based recording, developmental changes of spontaneous activity and tetanus-induced modification of evoked activity were studied. Rat cortical neurons were cultured on MEAs and the spontaneous activity was continuously monitored for two months. The activity started a few days after plating. During the second week, the cultures generated periodic synchronized bursts, which were the characteristic properties of cortical neurons in vitro. In about one month, the cultured networks reached a steady state. Between these two, we found a critical period during which only weak activities were generated. This critical period might reflect the transition from immature networks to mature networks including precisely controlled excitatory and inhibitory synapses. We could elicit clear evoked responses with high reproducibility in mature cultures. A focal tetanic stimulation was applied to the mature cultures and how the tetanus affects 64 kinds of evoked activity was studied. The evoked responses showed bi-directional changes in their propagation patterns, potentiation and depression. These induced changes reflected the correlation properties with the tetanized activity pattern. The next step will be the combination of long-term recording and multi-site stimulation. How long does the induced change last, as well as how additional strong activity affects the previously induced changes, will be studied.
    Preview · Article · Dec 2007 · Archives italiennes de biologie
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    ABSTRACT: Recently, Intra-Operative Magnetic Resonance Imaging (IO-MRI) has attracted attention for the reason of operating quality. In the other hand, surgical assist robot with high accuracy is widely researched. By combining IO-MRI and surgical assist robot to an MR-compatible surgical assist robot, higher quality of operation is expected. In this paper, we introduce a novel actuator for MR-compatible Surgical Assist Robot, which actively uses MR magnetic field and is drive by regulating pulse current. Use of ratchet mechanism enables step wise motion of the rotor similar to stepping motors. The position of the rotor can be controlled without an encoder. Clock-wise rotation, counter clock-wise rotation, constrained and non-constrained conditions were achieved by using this mechanism. Evaluation of the first prototype (84times76times58(mm<sup>3</sup>), 380 (gram)) shows that it is MR-compatible and has a very high positioning accuracy (step angle CW: 12.04plusmn0.28 (deg), CCW : 12.22plusmn0.36(deg); backlash < 1 (deg)). No-load maximum rotational speed is 35.71(rpm) and maximum torque 15.1times10<sup>-3</sup> (Nm).
    No preview · Conference Paper · Oct 2007
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    ABSTRACT: Finger Braille is one of tactual communication media of deafblind people. In finger Braille, index finger, middle finger and ring finger of both hands are likened to keys of a Braille typewriter. A sender dots Braille code on the fingers of a receiver like whether he/she does the type of the Braille typewriter. Then the receiver recognizes the Braille code. Deafblind people who are skilled in finger Braille can catch up with speech conversation and express various emotions. Because there are small non-disabled people who are skilled in finger Braille, deafblind people communicate only with interpreters. In this paper, we developed a finger Braille teaching system and designed a teaching interface which taught clauses explicitly. The teaching system recognized non-disabled people's speech and converted to Braille code. By parsing the Braille code, the teaching system retrieved clause information and segmented the Braille code into clauses. Then the dot pattern of the Braille code was displayed. By observing the dot pattern, non-disabled people dotted Finger Braille to deafblind people. An evaluation experiment between a blind person who was skilled in Finger Braille and two nondisabled people who were non-skilled in Finger Braille was carried out. The results showed that the fundamental functions (speech recognition, conversion to Braille code and clause segmentation) were practicable; the nondisabled senders could dot finger Braille accurately and communicate with the blind receiver directly. Therefore it was considered that the teaching system was effective.
    No preview · Conference Paper · Sep 2007
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    ABSTRACT: In order to probe the spatio-temporal activity of cultured neural network, microelectrode arrays (MEAs) have been widely used. MEAs, however, have limitations of their electrode numbers and densities, resulting in low spatial resolutions of stimulation and recording. Here, to overcome this problem, we propose and develop an experimental setup for light-addressed stimulation and simultaneous fluorescence calcium imaging, using the previously published light-addressable electrode. The electrode has a translucent thin-film-laminated structure and allows optical access from both sides of the substrate. We, thus, provided the fluorescence excitation light from the topside and an addressing illumination from the bottom. By instantly shutting out the fluorescence excitation light during the stimulus application, we prevented the excitation light from interfering with the addressing illumination. With this experimental setup, we successfully measured spatio-temporal patterns of neuronal activities evoked by light-addressed stimuli. Evoked fluorescence transients with hundred-millisecond latencies suggested the possibility that some neurons were activated by recurrent synaptic inputs, which were possibly overlooked by previous MEA studies.
    No preview · Conference Paper · Jun 2007

Publication Stats

2k Citations
53.48 Total Impact Points

Institutions

  • 2003-2014
    • The University of Tokyo
      • • Graduate School of Frontier Sciences
      • • Department of Precision Engineering
      白山, Tōkyō, Japan
  • 1993-2004
    • University of Cambridge
      • Department of Physiology, Development and Neuroscience
      Cambridge, England, United Kingdom
  • 1993-1999
    • NTT DOCOMO
      Edo, Tokyo, Japan
  • 1996-1998
    • Nippon Telegraph and Telephone
      Edo, Tōkyō, Japan