Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   International / domestic magazine：International journal  

The transmission of neuronal information is propagated through synapses by neurotransmitters released from presynapses to postsynapses. Neurotransmitters released from the presynaptic vesicles activate receptors on the postsynaptic membrane. Glutamate acts as a major excitatory neurotransmitter for synaptic vesicles in the central nervous system. Determining the concentration of glutamate in single synaptic vesicles is essential for understanding the mechanisms of neuronal activation by glutamate in normal brain functions as well as in neurological diseases. However, it is difficult to detect and quantitatively measure the concentration of glutamate in single synaptic vesicles owing to their small size, i.e., similar to 40 nm. In this study, to quantitatively evaluate the concentrations of the contents in small membrane-bound vesicles, we developed an optical trapping Raman spectroscopic system that analyzes the Raman spectra of small objects captured using optical trapping. Using artificial liposomes encapsulating glutamate that mimic synaptic vesicles, we investigated whether spontaneous Raman scattered light of glutamate can be detected from vesicles trapped at the focus using optical forces. A 575 nm laser beam was used to simultaneously perform the optical trapping of liposomes and the detection of the spontaneous Raman scattered light. The intensity of Raman scattered light that corresponds to lipid bilayers increased with time. This observation suggested that the number of liposomes increased at the focal point. The number of glutamate molecules in the trapped liposomes was estimated from the calibration curve of the Raman spectra of glutamate solutions with known concentration. This method can be used to measure the number of glutamate molecules encapsulated in synaptic vesicles in situ.

DOI： 10.1021/acsomega.1c07206

PubMed

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

AMPA-type glutamate receptor (AMPAR) is one of neurotransmitter receptors at excitatory synapses in neurons. For realizing the artificial control of synaptic transmission, we have applied optical trapping of quantum-dot (QD) conjugated AMPARs on neurons. Here, we evaluate optical trapping dynamics of QD-AMPARs on neurons by single particle tracking (SPT) analysis. The diffusion coefficient derived from mean square displacement (MSD) at laser focus of QD-AMPARs on neurons decreased with the laser irradiation and the culturing days, which suggests that the molecular dynamics of QD-AMPARs are constrained at the focal spot due to optical trapping forces.

DOI： 10.1541/ieejeiss.141.668

CiNii Article

J-GLOBAL

Publishing type：Research paper (scientific journal)  

We demonstrate surface plasmon resonance (SPR) based optical trapping of quantum-dot (QD) nanoparticles suspended in water with a bull's eye-type plasmonic chip. The particle dynamics of QD suspensions at the laser focus was evaluated by fluorescence correlation spectroscopy. The average transit time of QD suspensions on the plasmonic chip increased than that on the coverslip, suggesting that single QD was more constrained at the focal spot due to optical trapping enhanced with SPR.

DOI： 10.1117/12.2616159

Publishing type：Research paper (scientific journal)  

We numerically investigate the convection of surrounding fluid in optical trapping of micro- and nanoparticles. The effects of the laser irradiation on the fluid simulation are twofold. First, we take into account the temperature increase of the fluid due the photothermal effect of the solvent, that is, the fluid flow is described by the Navier-Stokes equations under the Boussinesq approximation. Second, we assume that the suspended particles drag the fluid when they are transported by the optical force. This dragging effect is considered in the fluid simulation by adding to the Navier-Stokes equation an external forcing term, which is modelled by considering the counterbalance between the optical scattering force and the Stokes drag. It is shown that the latter effect is dominant under the usual experimental setup in optical trapping of particles with the diameter larger than 0.5 μm. Furthermore, the particle size dependence on the convective flow speed is investigated. The numerical results are supported by optical trapping experiment qualitatively.

DOI： 10.1117/12.2616108

Publishing type：Research paper (scientific journal)  

© 2020 by the authors. The excitatory synaptic transmission is mediated by glutamate (GLU) in neuronal networks of the mammalian brain. In addition to the synaptic GLU, extra-synaptic GLU is known to modulate the neuronal activity. In neuronal networks, GLU uptake is an important role of neurons and glial cells for lowering the concentration of extracellular GLU and to avoid the excitotoxicity. Monitoring the spatial distribution of intracellular GLU is important to study the uptake of GLU, but the approach has been hampered by the absence of appropriate GLU analogs that report the localization of GLU. Deuterium-labeled glutamate (GLU-D) is a promising tracer for monitoring the intracellular concentration of glutamate, but physiological properties of GLU-D have not been studied. Here we study the effects of extracellular GLU-D for the neuronal activity by using primary cultured rat hippocampal neurons that form neuronal networks on microelectrode array. The frequency of firing in the spontaneous activity of neurons increased with the increasing concentration of extracellular GLU-D. The frequency of synchronized burst activity in neurons increased similarly as we observed in the spontaneous activity. These changes of the neuronal activity with extracellular GLU-D were suppressed by antagonists of glutamate receptors. These results suggest that GLU-D can be used as an analog of GLU with equivalent effects for facilitating the neuronal activity. We anticipate GLU-D developing as a promising analog of GLU for studying the dynamics of glutamate during neuronal activity.

DOI： 10.3390/MI11090830

PubMed

Publishing type：Research paper (scientific journal)  

Copyright © 2020 American Chemical Society. Plasmonic chips have wavelength-size periodic structures coated with thin metal films and can provide enhanced electric fields near the chip surfaces. Herein, a plasmonic chip was developed to carry out one-photon-excited emission (1PE) and two-photon-excited emission (2PE). Most studies on plasmon-assisted 2PE are based on the localized surface plasmon resonance. Among the propagated surface plasmon resonances (SPRs), we focused on the grating-coupled SPR. Quantum dots (QD655) dispersed on the silver plasmonic chip of the bull's eye patterns with a 600 nm pitch were excited by a near-infrared (NIR) laser with λ = 1064 nm. The emission intensity plotted against the irradiation light intensity was well fitted to a quadratic function for the plasmonic chip and coverslip. Therefore, the emission excited by NIR light was evaluated as 2PE. The coefficient of the quadratic part for the plasmonic chip was larger than that for the coverslip, and our plasmonic chip was found to promote the two-photon excitation. After correcting the molecule number at illumination spots, the enhancement factor of the 2PE evaluated in the plasmonic chip was found to be greater than 6-fold compared with that in the coverslip. The enhanced 2PE was assisted by the propagated plasmon field in the bull's eye-patterned plasmonic chip.

DOI： 10.1021/acs.jpcc.0c00826

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

DOI： https://doi.org/10.1117/12.2573759

Publishing type：Research paper (scientific journal)  

© 2020 American Chemical Society. Optical trapping dynamics of colloidal particles in solution is essential for understanding laser-induced assembling of molecules and nanomaterials, which contributes to nanofabrication, bioengineering, and microfluidics. In this paper, the importance of the surrounding fluid motion in optical trapping is investigated; that is, we reveal convection fluid dynamics forced by optical trapping with a focused laser beam. The fluid flow in optical trapping is evaluated by both experiments using the particle-image-velocimetry of fluorescent particles in solutions and theoretical consideration based on numerical analysis. A theoretical model consists of Navier-Stokes equations with the Boussinesq approximation that considers the temperature elevation induced by a photothermal effect. Furthermore, the effect of the particle motion induced by the optical force on fluid flow is also included in the analysis by developing a simple one-way homogeneous-type multiphase flow model. From both experimental and theoretical results, it turns out that the fluid flow in optical trapping is caused not only by thermal convection due to the temperature elevation but also by the collective particle motion induced by optical forces. Therefore, the optical forces can induce the large-scale fluid convection, which supports accumulating the target particles to the focal spot.

DOI： 10.1021/acs.jpcc.9b11663

Publishing type：Research paper (scientific journal)  

© 2020 Author(s). High-density cultured neuronal networks have been used to evaluate synchronized features of neuronal populations. Voltage-sensitive dye (VSD) imaging of a dissociated cultured neuronal network is a critical method for studying synchronized neuronal activity in single cells. However, the signals of VSD are generally too faint - that is, the signal-to-noise ratio (S/N) is too low - to detect neuronal activity. In our previous research, a silver (Ag) plasmonic chip enhanced the fluorescence intensity of VSD to detect spontaneous neural spikes on VSD imaging. However, no high-density network was cultivated on the Ag plasmonic chip, perhaps because of the chemical instability of the Ag surface. In this study, to overcome the instability of the chip, we used a chemically stable gold (Au) plasmonic dish, which was a plastic dish with a plasmonic chip pasted to the bottom, to observe neuronal activity in a high-density neuronal network. We expected that the S/N in real-time VSD imaging of the Au plasmonic chip would be improved compared to that of a conventional glass-bottomed dish, and we also expected to detect frequent neural spikes. The increase in the number of spikes when inhibitory neurotransmitter receptors were inhibited suggests that the spikes corresponded to neural activity. Therefore, real-time VSD imaging of an Au plasmonic dish was effective for measuring spontaneous network activity in a high-density neuronal network at the spatial resolution of a single cell.

DOI： 10.1063/1.5131497

PubMed

Publishing type：Research paper (international conference proceedings)  

AMPA- type glutamate receptor (AMPAR) is one of neurotransmitter receptors at excitatory synapses in neuronal cell. For realizing the artificial control of synaptic transmission, we have applied optical trapping of quantum-dot (QD) conjugated AMPARs on neuronal cells. Here, we demonstrate simultaneous measurement combined with optical trapping and patch-clamp recordings to evaluate the neuronal electrical activity. The relationship between optical trapping dynamics of QD-AMPARs located on neuronal cells and the neuronal electrical activity was discussed.

DOI： 10.1117/12.2573759

Publishing type：Research paper (scientific journal)  

© 2019 Elsevier B.V. We have demonstrated the real-time voltage sensitive dye (VSD) imaging of a neuronal network using Di-4-ANEPPS at a 1 ms-time resolution on a silver (Ag) plasmonic dish to improve the signals to noise (S/N) ratio. The plasmonic dish is composed of a culture dish and a metal-coated substrate with a wavelength-order periodical structure on its surface that can enhance excitation field due to the surface plasmon resonance (SPR)-field. In our group, spontaneous neural spikes that are undetectable on a conventional culture dish were frequently detected on a gold (Au) plasmonic dish during real-time VSD imaging. In the present study, Ag and Au plasmonic chips were prepared and tested. Larger fluorescence enhancement of the VSD was obtained on the Ag plasmonic dish compared with on the Au. Number of neural spikes were frequently detected on the Ag plasmonic dish compared to the Au plasmonic dish in the control neurons and after application picrotoxin (PTX), because of the photobleaching rate was suppressed and the noise level decreased by the reduction of illumination light on the Ag surface. Therefore, the use of an Ag plasmonic dish was considered to be suitable for the long-term and real-time observation by VSD imaging.

DOI： 10.1016/j.jphotochem.2019.111949

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work   International / domestic magazine：International journal  

DOI： 10.3934/Neuroscience.2019.4.240

Publishing type：Research paper (scientific journal)  

© 2012 IEEE. Neurons behave like transistors, but have fluctuating characteristics. In this paper, we show that several asynchronous multiplex communication channels can be established in a 2-D mesh neural network with randomly generated weights between eight neighbors. Neurons were simulated by integrate-and-fire neuron models without leakage and with fluctuating refractory period and output delay. If one of the transmitting neuron groups is stimulated, the signal is propagated in the form of spike waves. The corresponding receiving neuron group is able to identify the signal after having learned to form an asynchronous multiplex communication channel. The channel is composed of many intermediate/interstitial neurons working as relays. Each neuron can work as an I/O and as a relay element, i.e., as a multiuse unit. Grouping and synchronic firing is often seen in natural neuronal networks and seems to be effective for stable/robust communication in conjunction with spatial multiplex communication. This communication pattern corresponds to our wet lab experiments on cultured neuronal networks and is similar to sound identification by the ear and mobile adaptive communication systems.

DOI： 10.1109/TNNLS.2018.2880565

PubMed

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

© 2019 The Japan Society of Applied Physics. We reveal the characteristics of Brownian motion in nanoparticle clusters formed by the optical force fields at a solid-liquid interface based on the trajectory analysis from the microscopy movie data. The characteristics of stochastic motion depend not only on the laser power but also on the location in the clusters. The particles at the focal points exhibit smaller displacements, compared to the surrounding particles that are nevertheless trapped. The nominal diffusion coefficient is larger than the bulk at sufficiently small time scale for sufficiently high laser powers, although it decreases as a function of time because of the confinement. Decomposition of radial and circumferential components of displacements reveals the anisotropy as well as non-uniformity of the dynamics.

DOI： 10.7567/1347-4065/ab0887

Other URL： https://doi.org/10.7567/1347-4065/ab0887

Publishing type：Research paper (international conference proceedings)  

© Published under licence by IOP Publishing Ltd. It is well-recognized that the Brownian motion of particles in fluids is random. Nevertheless, there can be characteristics depending on the specific physical conditions. We analyze the system of nanoparticle clusters formed by the laser trapping force field at the solid-liquid interface, based on the microscopy movie data. Since the laser trapping force field is basically a function of radial distance from the focal point in the two dimension at the liquid-solid interface, we examine the difference of displacement distributions in the radial and circumferential directions. The results show that the basic characteristics in this system depends on the laser power, and there is an anisotropy in the stochastic motion of the nanoparticles.

DOI： 10.1088/1742-6596/1220/1/012015

Publishing type：Research paper (international conference proceedings)  

© Published under licence by IOP Publishing Ltd. Nanoparticles in a cluster trapped by laser-induced force field show Brownian motion at solid-liquid interfaces. The cluster formation means that the particles are highly concentrated. In general, the diffusion coefficients of particles in fluids decrease with substantially high concentration and also in the vicinity of solid walls due to the hydrodynamic effect. The particle trajectory data obtained from the experimental measurements show that the longer time span of observation leads to smaller diffusion coefficient due to the confinement effect. However, they also exhibit higher diffusion coefficient compared to the the bulk condition when evaluated at a sufficiently short time span of the frame interval under the condition of sufficiently high laser powers.

DOI： 10.1088/1742-6596/1220/1/012054

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

© Optics & Photonics International Congress 2019. For the purpose of artificial control in synaptic transmission on neuronal cells with optical trapping, we demonstrate optical trapping with resonance effect of nanoparticles and cell surface molecules by simultaneous irradiation with nonresonance and resonance laser beams. The average transit times of quantum-dot (QD) suspensions increased by the simultaneous irradiation with NIR laser and resonance laser, suggesting that single QD was more constrained at the focal spot due to optical trapping potential enhanced with resonance laser irradiation. Moreover, we applied the resonance laser effect to manipulate QD-conjugated AMPA-type glutamate receptors on neuronal cells.

Other URL： http://orcid.org/0000-0002-0289-4680

Publishing type：Research paper (scientific journal)  

DOI： 10.3934/Neuroscience.2019.4.240

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.1039/c8nj02465k

Publishing type：Research paper (scientific journal)  

© 2018 American Chemical Society. Optical trapping and manipulation techniques have attracted significant attention in various research fields. Optical forces divided into two terms, such as a scattering force and gradient one, work to push forward and attract objects, respectively. This is a typical property of optical forces. In particular, a tool known as optical tweezers can be created when a laser beam is converged at a focal point, causing strong forces to be generated so as to trap and manipulate small objects. In this study, we propose a novel method to build up assembled structures of polystyrene particles by using optical trapping techniques. Recording trajectories of single particles, the optical forces are quantitatively evaluated using particle tracking velocimetry. Herein, we treat various particle sizes whose diameters range from 1 to 4 μm and expose them to a converged laser beam of 1064 nm wavelength. As a result, both experimental and theoretical results are in good agreement. The behavior of particles is understood in the framework of Ashkin's ray optics. This finding clarifies optical force fields of microparticles distributed in a slit-like microfluidic channel and will be applicable for effectively forming ordered structures in liquids.

DOI： 10.1021/acs.jpcc.8b02701

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

© 2018 the Author(s). Neuronal networks have fluctuating characteristics, unlike the stable characteristics seen in computers. The underlying mechanisms that drive reliable communication among neuronal networks and their ability to perform intelligible tasks remain unknown. Recently, in an attempt to resolve this issue, we showed that stimulated neurons communicate via spikes that propagate temporally, in the form of spike trains. We named this phenomenon "spike wave propagation". In these previous studies, using neural networks cultured from rat hippocampal neurons, we found that multiple neurons, e.g., 3 neurons, correlate to identify various spike wave propagations in a cultured neuronal network. Specifically, the number of classifiable neurons in the neuronal network increased through correlation of spike trains between current and adjacent neurons. Although we previously obtained similar findings through stimulation, here we report these observations on a physiological level. Considering that individual spike wave propagation corresponds to individual communication, a correlation between some adjacent neurons to improve the quality of communication classification in a neuronal network, similar to a diversity antenna, which is used to improve the quality of communication in artificial data communication systems, is suggested.

DOI： 10.3934/Neuroscience.2018.1.18

Other URL： http://orcid.org/0000-0002-0289-4680

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

DOI： 10.1117/12.2319362

Other URL： http://orcid.org/0000-0002-0289-4680

Publishing type：Research paper (scientific journal)  

© 2018 OSA - The Optical Society. All rights reserved. Fluorescent imaging is a powerful technique to reveal how target cells or biomolecules work in biological tissues and cells. So far, organic dyes, fluorescent proteins, and quantum dots have been developed and widely used as a fluorescent probe. However, these fluorescent probes do not work well in certain conditions: they have cytotoxicity and steric hindrance due to inclusion of harmful atoms and/or their sizes. Hence, metal nanoclusters, that are composed of several metal atoms and emit fluorescence owing to quantum size effect, have been anticipated as a newly categorized fluorescent probe. Since the fluorescent wavelength depends on their sizes, it is possible to control the fluorescent wavelength by adjusting the number of composed atoms [1].

Publishing type：Research paper (international conference proceedings)  

Copyright© (2018) by Chemical and Biological Microsystems Society.All rights reserved. Optical forces are well known as providing a noncontact method of manipulating micro- or nano-sized particles. In previous studies, however, it has been reported that the trapping power of the optical tweezers is smaller than that of the movement of the particles (eg. Brownian motion) and it becomes unstable trapping. Since the trapping force decreases in proportion to the size of the target, it is extremely difficult to precisely manipulate nano-sized particles. On the other hand, the use of ultrasmall confined spaces of well-defined nanofluidic environments will provide new mechanisms and technologies for manipulating nano-sized particles in liquid phase. These features contribute to the suppression of the Brownian motion of nanoparticles in 3D nano space. The integration of optical forces and nanofluidics would allow single nanoparticles to be captured, transported and arrayed in nanofluidic systems.

Publishing type：Research paper (scientific journal)  

© The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. InP-based quantum dots (QDs) have been proposed as an alternative to CdSe-based QDs for both bioimaging and device displays. In this work, we incorporate hydrophilic InP/ZnS QDs into silica nanocapsules. The morphology, number of incorporated QDs, and photoluminescence (PL) properties of the capsules depend on the alkoxide hydrolysis conditions. By selecting a method of QD surface silanization, multiple QDs (typically 3) are incorporated into the nanocapsules (∼40 nm in size) without causing significant deterioration of the initial PL efficiency (up to 36%). Degradation analysis in different buffer solutions indicates that silica nanocapsules have higher stabilities than pristine QDs. The surface of the nanocapsules was modified with carboxyl groups without any change in morphology. Bright PL images with high resolution were obtained after introducing the nanocapsules into rat hippocampal neurons, when compared with commercial Q-trackers (polymer coated CdSe/ZnS QDs).

DOI： 10.1039/c8nj02465k

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.1364/OE.25.010622

Other URL： http://orcid.org/0000-0002-0289-4680

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

DOI： 10.1117/12.2275026

Other URL： http://orcid.org/0000-0002-0289-4680

Publishing type：Research paper (international conference proceedings)  

© 2016 IEEE. It is a mystery that neural network composed of neurons with fluctuating characteristics can transmit information well reliably. In this paper, we show, in a simulation using a 9×9 2D mesh neural network, 9 to 1 multiplex communication is possible with 99% correct rate. Neurons are modeled by integrate and fire model without leak. Spikes spreads from transmitting neuron groups, propagated as spike waves, and received by receiving neurons. Then, the receiving neurons classify from which neuron group the spike waves come by back propagation neural network (BPN) method.

DOI： 10.1109/CISP-BMEI.2016.7852824

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.3934/Neuroscience.2017.1.1.

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.3934/Neuroscience.2016.4.385.

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

© 2016 The Japan Society of Applied Physics.Living neurons in a complex neuronal network communicate with each other through synaptic connections. The molecular dynamics of cell surface molecules localized at synaptic terminals is essential for functional connections via synaptic plasticity in the neuronal network. Here, we demonstrate surface-plasmon-resonance-based optical trapping using a plasmonic chip toward realizing effective manipulation of molecules on the surface of neurons. Surface-plasmon-enhanced optical trapping was evaluated by the fluorescence analysis of nanoparticles suspended in water and neural cell adhesion molecules (NCAMs) labeled with quantum dots (Q-dots) on rat hippocampal neurons. The motion of nanoparticles in water and the molecular dynamics of NCAMs on neuronal cells cultured on a plasmonic chip were constrained at the laser focus more effectively than those on a glass substrate because of the surface plasmon resonance effect.

DOI： 10.7567/JJAP.55.06GN04

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

© 2016 The Japan Society of Applied Physics. A plastic dish with a wavelength-scale periodic structure at a bottom panel was integrally molded and coated with thin metal films. The integrally molded dish called plasmonic dish was applied to bioimaging under a fluorescence microscope. On the plasmonic substrate, the enhanced electric field based on a grating-coupled surface plasmon resonance (GC-SPR) can provide an enhanced fluorescence. In this study, two kinds of cells, human embryonic kidney (HEK) cells and neuronal cells, were observed in our plasmonic dish. Fluorescence images of HEK cells were above 10 times brighter than those obtained on a conventional glass-bottomed dish. Neuronal cells were successfully cultured for 10 d on the plasmonic dish integrally molded, and in fluorescence images with transmitted light, a higher contrast was obtained than in epifluorescence images. The plasmonic dish integrally molded, as well as that fabricated by the UV nanoimprint method, was also found to be useful for sensitive bioimaging.

DOI： 10.7567/JJAP.55.03DF12

Publishing type：Research paper (international conference proceedings)  

© 2015 IEEE. It's important for understanding brain intelligence to investigate how the signal/information is flown in neuronal network. We observed spike trains obtained by one-shot electrical stimulation with 8 × 8 multi-electrodes in cultured neuronal networks. Each electrode is considered to collect spikes from several neurons. We then constructed code flow maps as movies of the electrode array to observe the code flow especially of 1101 and 1011. To quantify the flow, we calculated the cross-correlations of the maximum direction of the codes with lengths less than 8. Normalized cross-correlations in the maximum direction were almost constant irrespective of code. Thus, the analysis suggested that the local codes for electrode flow maintained the code shape to some extent and conveyed information in the neural network. Then we made simulation of such code flow, and could estimate rough characteristics of neurons including refractory period and distribution of connection weights between neurons.

DOI： 10.1109/FSKD.2015.7382211

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.1155/2016/7186092

Other URL： http://dblp.uni-trier.de/db/journals/cin/cin2016.html#journals/cin/TamuraNHMS16

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.1155/2016/7267691

Other URL： http://dblp.uni-trier.de/db/journals/cin/cin2016.html#journals/cin/TamuraNHMSKYMC16

Publishing type：Research paper (scientific journal)  

© 2016 Shinichi Tamura et al. It remains a mystery how neural networks composed of neurons with fluctuating characteristics can reliably transmit information. In this study, we simulated a 9 × 9 2D mesh neural network consisting of an integrate-and-fire model without leak, and connection weights that were randomly generated. The characteristics of the refractory period and output delay of the neurons were fluctuated time to time. Spikes from transmitting neuron groups spread (propagated as spike waves) to receiving neurons. For 9 to 1 multiplex communication with a back propagation neural network (BPN), the receiving neurons successfully classified which neuron group transmitted the spike at a rate of 99%. In other words, the activity of the neuron group is propagated in the neural network as spike waves in a broadcasting manner and the wave fragment is received by receiving neurons. Next, point-to-point signal transmission in the neural network is carried out by multi-path, multiplex communication, and diversity reception. Each neuron can function in 3 ways of transmit, relay (transfer), and receive; however, most neurons act as a local relaying media. This type of mechanism is similar to sound propagation through air. Our research group studies the functions of neural networks by combining experiments with cultured neuronal networks with artificial neural network simulations. This current study corresponding to our previous work on the ability of remote receiving neurons to identify two transmitting neuron groups stimulated in a cultured neuronal network, i.e., 2 to 1 communication. These mechanisms may be the basis of higher cortical functions.

DOI： 10.3934/Neuroscience.2016.4.385

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (international conference proceedings)  

© 2015 IEEE. It's important to investigate natural intelligence how the signal/ information is flown in neuronal network. We observed spike trains produced by one-shot electrical stimulation with 8 × 8 multi-electrodes in cultured neuronal networks. Each electrode accepted spikes from several neurons. We then constructed code flow maps as movies of the electrode array to observe the code flow especially of '1101' and '1011.' To quantify the flow, we calculated the cross-correlations of the maximum direction of the codes with lengths less than 8. Normalized cross-correlations in the maximum direction were almost constant irrespective of code. Thus, the analysis suggested that the local codes for electrode flow maintained the code shape to some extent and conveyed information in the neural network. Then we made simulation of such code flow.

DOI： 10.1109/ICCIS.2015.7274571

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

DOI： 10.1109/FSKD.2015.7382211

Other URL： http://dblp.uni-trier.de/db/conf/fskd/fskd2015.html#conf/fskd/TamuraNHMC15

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

DOI： 10.1117/12.2076348

Publishing type：Research paper (scientific journal)  

© 2014 American Chemical Society. A plasmonic dish was fabricated as a novel cellculture dish for in situ sensitive imaging applications, in which the cover glass of a glass-bottomed dish was replaced by a grating substrate coated with a film of silver. Neuronal cells were successfully cultured over a period of more than 2 weeks in the plasmonic dish. The fluorescence images of their cells including dendrites were simply observed in situ using a conventional fluorescence microscope. The fluorescence from neuronal cells growing along the dish surface was enhanced using the surface plasmon resonance field. Under an epi-fluorescence microscope and employing a donut-type pinhole, the fluorescence intensity of the neuron dendrites was found to be enhanced efficiently by an order of magnitude compared with that using a conventional glass-bottomed dish. In a transmitted-light fluorescence microscope, the surface-selective fluorescence image of a fine dendrite growing along the dish surface was observed; therefore, the spatial resolution was improved compared with the epi-fluorescence image of the identical dendrite. (Chemical Equation Presented).

DOI： 10.1021/am505579u

PubMed

Publishing type：Research paper (scientific journal)  

Other URL： http://orcid.org/0000-0002-5736-1187

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.1541/ieejeiss.134.1071

J-GLOBAL

Publishing type：Research paper (other academic)   Kind of work：Joint Work  

Other URL： http://orcid.org/0000-0002-0289-4680

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

Publishing type：Research paper (scientific journal)  

© 2014 The Institute of Electrical Engineers of Japan. Living neuronal network in neural systems communicate through synaptic connections. For aiming artificial control of the synaptic transmission in neuronal network, we have applied conventional optical tweezers using a focused near-infrared (NIR) laser. The optical trapping of neural cell adhesion molecules (NCAMs) labeled with quantum-dots (Q-dots) at the plasma membrane of living neuronal cells was achieved at high laser power (> 300 mW) in our previous study; therefore, the further reduction of laser power was required. Here, we propose and demonstrate resonant optical tweezers of Q-dots attached to NCAM in a neuron by simultaneous irradiation with non-resonance and resonance laser beams. The optical trapping dynamics of them was revealed by fluorescence correlation spectroscopy (FCS). The transit times of Q-dots attached to NCAM at the focal spot increased with the simultaneous irradiation of NIR laser and resonance laser. These results suggest that the particle motion of Q-dots attached to NCAM was constrained at the focus spot due to optical trapping force enhanced with resonance laser irradiation. Our method is applicable to selective manipulation of signaling molecules in living neurons.

DOI： 10.1541/ieejeiss.134.1071

J-GLOBAL

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.11648/j.acis.20130106.11

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

DOI： 10.1109/CLEOPR.2013.6600270

Publishing type：Research paper (scientific journal)  

We demonstrated the stimulation of neurons at a single-cell level in cultured neuronal network by a focused femtosecond laser. When the femtosecond laser was focused on a neuron loaded with a fluorescent calcium indicator, the fluorescence intensity immediately increased at the laser spot, suggesting that intracellular Ca2+ increases in the neuronal cell due to the femtosecond laser irradiation. The probability of Ca2+ elevation at the laser spot depended on the average laser power, irradiation time, and position of the focal point along the optical axis, indicating that the femtosecond laser activates neurons because of multiphoton absorption. Moreover, after laser irradiation of a single neuron cultured on multielectrode arrays, the evoked electrical activity of the neurons was demonstrated by electrophysiological systems, which concluded that the focused femtosecond laser could achieve stimulating a single neuron in a neuronal network with high spatial and temporal resolution. © Springer-Verlag 2012.

DOI： 10.1007/s00339-012-7137-6

Other URL： http://orcid.org/0000-0002-0289-4680

Publishing type：Research paper (scientific journal)  

DOI： 10.1364/jsap.2013.16p_d5_8

Publishing type：Research paper (international conference proceedings)  

We demonstrated laser manipulation of intracellular molecular dynamics in neurons to realize artificial control toward modulating synaptic transmission in a neuronal network. The optical trapping and assembling dynamics of synaptic vesicles and neural cell adhesion molecules in neurons was revealed by fluorescence analysis. © 2013 IEEE.

DOI： 10.1109/CLEOPR.2013.6600270

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.1038/ncomms2233

PubMed

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.1143/JJAP.51.06FK10

J-GLOBAL

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.1071/CH12127

Publishing type：Research paper (scientific journal)  

In circuit theory, it is well known that a linear feedback shift register (LFSR) circuit generates pseudorandom bit sequences (PRBS), including an M-sequence with the maximum period of length. In this study, we tried to detect M-sequences known as a pseudorandom sequence generated by the LFSR circuit from time series patterns of stimulated action potentials. Stimulated action potentials were recorded from dissociated cultures of hippocampal neurons grown on a multielectrode array. We could find several M-sequences from a 3-stage LFSR circuit (M3). These results show the possibility of assembling LFSR circuits or its equivalent ones in a neuronal network. However, since the M3 pattern was composed of only four spike intervals, the possibility of an accidental detection was not zero. Then, we detected M-sequences from random spike sequences which were not generated from an LFSR circuit and compare the result with the number of M-sequences from the originally observed raster data. As a result, a significant difference was confirmed: a greater number of 01 reversed the 3-stage M-sequences occurred than would have accidentally be detected. This result suggests that some LFSR equivalent circuits are assembled in neuronal networks. © Copyright 2012 Yoshi Nishitani et al.

DOI： 10.1155/2012/862579

PubMed

Publishing type：Research paper (scientific journal)  

Electrifying! A device based on carbon nanotubes wrapped with poly(3-hexylthiophene) (and dispersed in poly(dimethylsiloxane)) sheets can effectively convert laser light into thermal energy and subsequently to electricity. The converter is flexible and extremely compact (see picture), and can be manipulated by using a laser that functions in the wavelength range that can be transmitted through living tissue. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/anie.201106136

PubMed

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.1063/1.3579191

Publishing type：Research paper (scientific journal)  

We have developed a neuro-robot-hybrid system using a living neuronal network and a miniature moving robot. The living network of rat hippocampal neurons can distinguish patterns of action potentials evoked by different inputs, suggesting that a cultured neuronal network can represent particular states as symbols. We used a Khepera II robot and a robot made using a LEGO mindstorm NXT kit to interface with a living neuronal network and the outer world. We call the system 'vitroid'. Vitroid has living neurons, a robot body, and direct coupling controllers to interface the neurons with the robot. Vitroid was able to perform obstacle avoidance behaviour with premised control rule sets. Copyright © 2011 Inderscience Enterprises Ltd.

DOI： 10.1504/IJMMS.2011.039264

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

DOI： 10.1016/j.neures.2011.07.894

Publishing type：Research paper (scientific journal)  

We propose and demonstrate micro-channel fabrication by femtosecond-laser processing to arrange neuronal cells on multi-electrode arrays (MEAs). When neuronal cells were seeded in the micro-channels on MEAs, they elongated their neurites along the channel and finally formed the network patterned on MEAs. The spontaneous electrical activity of the neuronal networks on MEAs was evaluated by using electrophysiological systems, indicating that patterned network was functionally activated along the channels. The present method is applicable to analyze network dynamics of living neuronal cells patterned artificially. © 2010 Springer-Verlag.

DOI： 10.1007/s00339-010-5836-4

CiNii Article

Publishing type：Research paper (scientific journal)  

A method including surface silanization, phase transfer and self-assembly, and SiO2 shell growth has been developed to incorporate multiple hydrophobic CdSe/ZnS nanocrystals into SiO2 beads where they are well suited for bio-application due to their high brightness, less-cytotoxic, and non-blinking nature. © 2010 The Royal Society of Chemistry.

DOI： 10.1039/c002243h

PubMed

CiNii Article

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

DOI： 10.1016/j.neures.2010.07.1034

Publishing type：Research paper (international conference proceedings)  

The rat hippocampal neurons were cultured on a dish with 64 planer micro electrodes array. Neurons reorganized a functional network, and an external inputs form outer world elicited a reproducible, particular spatiotemporal pattern of evoked action potentials. The patterns were not completely uniform for repeptive stimulation but varied slightly. We previously reported that dissociated rat hippocampal neurons possessed hysterical function in its network dynamics. The spatio-temporal electrical activity of the living neuronal network evoked by paired stimulation is quite different from one evoked by a single stimulation, suggested that the network can "memorize" an existence of precedent stimulation. In this report, the feature of this type of network hysteresis was investigated and the hysteresis was kept for at least 1s and not kept for 10s. In addition, this hysteresis was remarkable only in aged cultures with matured complex network. Network hysteresis depends on internal state of the network, generated by the autonomous activity in self-organized networks. ©2010 IEEE.

DOI： 10.1109/MHS.2010.5669566

Publishing type：Research paper (scientific journal)  

An all-wet femtosecond laser microprocessing technique was utilized for patterning and cutting functional network of living neuronal cells on a multi-electrode dish (MED). The neuronal cells cultured on a source substrate were transferred onto an electrode in a MED probe in solution by utilizing a femtosecond laser-induced impulsive force and a pattern of neuronal cells were formed on the MED probe. The cellular activity of the detached neurons was supported that neurites could be regenerated around the electrodes. As another processing method, the neurons stretching between electrodes were selectively cut by the direct femtosecond laser irradiation and the spontaneous electrical activity of the neuronal network was evaluated. While the spontaneous action potentials of neurons were synchronized before the cutting, the synchronization disappeared after the cutting, indicating that the neuronal network is locally disconnected by the laser cutting. The present method is applicable to artificial reconstruction of living neuronal network. © 2008 Springer-Verlag.

DOI： 10.1007/s00339-008-4655-3

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.1097/WNR.0b013e3282fdf6b3

PubMed

Publishing type：Research paper (international conference proceedings)  

Rat hippocampal neurons organized complex networks on a culture dish which has 64 planar microelectrodes and the spontaneous action potentials were frequently observed. The living neuronal network was able to distinguish patterns of action potentials evoked by different inputs, suggesting that a cultured neuronal network can represent and process particular states as symbols. We use a Khepera II robot and a robot made by LEGO mindstorm NXT kit as a robot body for interfacing with a living neuronal network and the outer world. We call the system "Vitroid". Vitroid has the living neurons, robot body, and direct coupling type of controllers to interface neurons with the robot. We succeeded in performing obstacle avoidance behavior with premised control rule sets. Using self-tuning fuzzy reasoning, we associated a distinct spatial pattern of electrical activity with a particular phenomenon in the outside of the culture dish. © 2008 IEEE.

DOI： 10.1109/ICMA.2008.4798783

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

We investigated laser-induced phase transition dynamics of μm sized single poly(N-isopropylacrylamide) hydrogel particles in water. Single poly(N--isopropylacrylamide) gel particles labeled with a polarity-sensitive fluorescent probe monomer were optically trapped by a focused laser beam and its fluorescence dynamics was analyzed. The fluorescence intensity of trapped single gel particles was increased with the trapping laser power, while the fluorescence peak wavelength was not changed. Temperature-induced changes of fluorescence properties of the single particle were confirmed to be similar to those of the bulk solution. These behaviors are well interpreted by considering that the fluorescence intensity and fluorescence peak reflect local interactions between the fluorescent probe and attaching (bound) water molecules and effective polarity determined by (free) water content in the particle, respectively. A change in the fluorescence peak wavelength after laser trapping was followed and its blue-shift was confirmed to occur within a few hundreds seconds, indicating that a single gel particle gradually attains to a globular state on this timescale, expelling initially free water molecules and then bound ones.

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

Other URL： http://dblp.uni-trier.de/db/journals/jrm/jrm19.html#journals/jrm/KudohHKTH07

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

DOI： 10.1016/j.neures.2007.06.1433

Publishing type：Research paper (international conference proceedings)   Kind of work：Joint Work  

DOI： 10.1109/MHS.2007.4420824

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

We propose and demonstrate the enhancement of the biased diffusion of dye-doped nanoparticles using resonance and nonresonance laser beams. The Brownian motion of nanoparticles in a laser focus is investigated by fluorescence correlation spectroscopy (PCS) and the time variation in fluorescence intensity. From the analysis of autocorrelation functions, it is demonstrated that the difference between the transit times of nanoparticles in the focal spot with and without resonance laser irradiation increases ∼7-fold by the simultaneous irradiation of a near-infrared laser. This method is applicable to the selective optical manipulation of dye-stained nanomaterials and biomolecules in solution. © 2006 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.45.L453

Publishing type：Research paper (scientific journal)  

When laser beam was focused into nanoparticle suspensions, nanoparticles can be trapped in the focal spot due to optical gradient force. Here we report the optical trapping and fluorescence analysis of poly(N-isopropylacrylamide) (PNIPAM) and its related polymer microgel particles which were labeled with 4-N-(2-acryloyloxyethyl)-N-methylamino-7-N,N-dimethylaminosulfonyl-2,1, 3-benzoxadiazole (DBD-AE) dispersed in water. The DBD-AE labeled PNIPAM microgel particles were trapped at the focal point by irradiation with cw-Nd 3+:YAG laser (λ = 1064 nm) in water and the fluorescence intensity of the DBD-AE labeled PNIPAM microgel particles excited by diode laser (λ = 405 nm) increased stepwise. We succeeded to fluorescence analysis of trapped single microgel particle.

Publishing type：Research paper (scientific journal)   Kind of work：Joint Work  

DOI： 10.1103/PhysRevE.72.021408

Publishing type：Research paper (scientific journal)  

We report in situ observation of cluster growth of nanoparticles confined in an optical trapping potential by means of fluorescence correlation spectroscopy. When an optical trapping force caused by a highly focused laser beam acts on nanoparticle suspensions, the number of nanoparticles increases and an assembly can be formed at the focal spot. The decay times of fluorescence autocorrelation curves were investigated as a function of the irradiation time of the laser beam and the laser power. In the initial stage of the optical assembling, the decay time increases with the irradiation time of the laser beam. On the other hand, in the later stage, a decrease of the decay time was observed. This behavior is explained successfully by using two models of Brownian motion under weak and strong optical trapping. It was revealed that trapping and clustering of nanoparticles proceed simultaneously and clusters confined in the focal spot make larger aggregates spontaneously. © 2005 The American Physical Society.

DOI： 10.1103/PhysRevE.72.021408

PubMed

Publishing type：Research paper (scientific journal)  

Reverse transcription of the HIV-1 RNA genome involves several complex nucleic acid rearrangement steps that are catalyzed by the HIV-1 nucleocapsid protein (NC), including for example, the annealing of the transactivation response (TAR) region of the viral RNA to the complementary region (TAR DNA) in minus-strand strong-stop DNA. We report herein single-molecule fluorescence resonance energy transfer measurements on single immobilized TAR DNA hairpins and hairpin mutants complexed with NC (i.e., TAR DNA/NC). Using this approach we have explored the conformational distribution and dynamics of the hairpins in the presence and absence of NC protein. The data demonstrate that NC shifts the equilibrium secondary structure of TAR DNA hairpins from a fully "closed" conformation to essentially one specific "partially open" conformation. In this specific conformation, the two terminal stems are "open" or unwound and the other stems are closed. This partially open conformation is arguably a key TAR DNA intermediate in the NC-induced annealing mechanism of TAR DNA. Copyright 2004 Biophysical Society

DOI： 10.1529/biophysj.104.043083

PubMed

Publishing type：Research paper (scientific journal)  

When a laser beam is focused into colloidal nanoparticle suspensions, a number of nanoparticles can be confined in the focal spot due to an optical gradient force. To reveal the assembling dynamics of polymer nanoparticles, the assembling process was investigated by analyzing the time evolution of the fluorescence intensity of the nanoparticles. In a dilute suspension of 100-nm-sized particles, a stepwise increase of the fluorescence intensity corresponding to a trapped single nanoparticle was observed. Statistical analysis revealed that the initial assembling rate of nanoparticles was proportional to the laser power and concentration of particle suspensions as expected from the diffusion equation. In 40-nm-sized particle suspensions, blinking profiles of fluorescence intensity were obtained, in which 2–3 particles were simultaneously trapped and then escaped from the focal point. It is considered from statistical analyses and two-dimensional Monte Carlo simulations that this assembling phenomenon is attributable to cluster formation assisted by optical trapping. © 2004 The American Physical Society.

DOI： 10.1103/PhysRevE.70.061410

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Kind of work：Single Work  

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

CiNii Article

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Kind of work：Single Work  

CiNii Article

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Kind of work：Single Work  

CiNii Article

J-GLOBAL

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Kind of work：Single Work  

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

J-GLOBAL

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

J-GLOBAL

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

J-GLOBAL

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Kind of work：Single Work  

CiNii Article

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

In circuit theory it is well known that loop circuit with a feedback link generates a pseudo-random sequence including an M-sequence with maximum period length. On the other hand, it remains unclear how memory is stored in neural circuits of the human brain. We propose that M-sequence composes temporal independent basis functions in brain neural network for communication and memory storage. We have already shown its feasibility by computer simulations that show a loop circuit can be copied to another area by back-propagation leaning algorithm; this is a key function of brain intelligence, which includes functions such as memory, association, reasoning, and abstraction. We found M-sequence responses in the instantaneous firing rates from cultured neural networks of published data and our own data, which suggest the existence of loop circuits with a feedback link composed of 3 to 5 neuron cells. Analyzing the time sequence of spike intervals of cultured neural network with the "auto mutual-information function," we also find evidence that suggests the existence of loop circuits with a feedback link composed of 3, 4 neurons.

CiNii Article

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

CiNii Article

J-GLOBAL

DOI： 10.2142/biophys.52.S26_4

We consider that the memory is composed of loop neural circuit in the cerebral cortex. We have already shown a feasibility of self organization of loop neural circuit for memory, association, and abstraction in our previous study. However, it remains unclear that how the memory is stored and transferred in real neural circuit. In this study, we found pseudo random sequences from cultured neuron networks, which suggest the existence of loop circuit with 3 elements and feedback link.

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

CiNii Article

J-GLOBAL

Quantum dots (QDs) show bright photoluminescence whose emission wavelength can be controlled by their particle size and composition. Compared with organic fluorescent dyes, QDs are more resistant to light irradiation. Because of those advantages, QDs attract much interest as novel bright fluorescent reagents. Photoluminescent QDs are synthesized in solution. However, QDs in solution are not very stable and tend to degradate. Therefore, we developed techniques to incorporate multiple QDs such as CdSe and InP in a small glass bead (diameter: several tens nm) by using sol-gel method at room temperature and under atmospheric pressure. The QD-incorporating glass beads are water-dispersible and emit bright photoluminescence. When dispersed in buffer solution for biological use, the glass beads showed much higher stability and light-resistance than commercial polymer-coated QDs. It was possible to obtain high-resolution fluorescence image of living neuronal cells by introducing the glass beads in the cells by endocytosis.

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

CiNii Article

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

The intense electromagnetic field produced by a focused laser beam attracts microparticles, dispersed in liquid, into the focal spot. This is known as optical trapping and used to manipulate microparticles dispersed in liquid. If the size of the particles is much smaller than that of the focal spot, i.e. the order is of wavelength, a number of particles are trapped in the focal spot. This means that the focal spot of the laser beam acts as a microcage for nanoparticles and the confined nanoparticles form a microassembly. Nanoparticles are attractive materials for their characteristic chemical, physical, and optical properties. We have studied "optical assembly" of nanoparticles and found the following unique properties. (1) By a single particle counting measurement, it was revealed that the assembling process of polystyrene nanoparticles is dependent on laser power and concentration. (2) It was demonstrated that the assembly structure and optical properties of gold-nanoparticles can be controlled by optical force.

DOI： 10.1380/jsssj.26.681

CiNii Article

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Venue：Washington, D.C., USA  

Presentation type：Poster presentation  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (invited, special)  

Venue：静岡県浜松市  

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Presentation type：Oral presentation (general)  

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Presentation type：Poster presentation  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

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Venue：大阪公立大学、大阪府大阪市  

Presentation type：Poster presentation  

Venue：Sapporo, Japan  

Presentation type：Oral presentation (general)  

Venue：Sapporo, Japan  

Presentation type：Poster presentation  

Venue：Sapporo, Japan  

Presentation type：Oral presentation (invited, special)  

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Presentation type：Poster presentation  

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Venue：Yokohama, Japan  

Presentation type：Oral presentation (general)  

Venue：Yokohama, Japan  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

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Presentation type：Poster presentation  

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Presentation type：Oral presentation (general)  

Presentation type：Poster presentation  

Venue：大阪公立大、大阪府大阪市  

Presentation type：Oral presentation (invited, special)  

Venue：大阪大学、大阪府豊中市  

Presentation type：Oral presentation (invited, special)  

Venue：大阪大学、大阪府豊中市  

Presentation type：Oral presentation (general)  

Venue：Adelaide, Australia  

Presentation type：Poster presentation  

Venue：Adelaide, Australia  

Presentation type：Oral presentation (general)  

Venue：兵庫県神戸市  

Presentation type：Oral presentation (invited, special)  

Venue：Tokushima, Japan  

Presentation type：Poster presentation  

Venue：Tokushima, Japan  

Presentation type：Poster presentation  

Venue：Tokushima Univ., Tokushima  

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Presentation type：Poster presentation  

Presentation type：Poster presentation  

Venue：大阪大学、大阪府吹田市  

Presentation type：Oral presentation (general)  

Presentation type：Poster presentation  

Venue：大阪大学、大阪府吹田市  

Presentation type：Poster presentation  

Venue：函館アリーナ、北海道函館市  

Presentation type：Poster presentation  

Venue：函館アリーナ、北海道函館市  

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Presentation type：Oral presentation (general)  

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Venue：Bayreuth, Germany  

Presentation type：Oral presentation (invited, special)  

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Presentation type：Oral presentation (general)  

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Venue：Sapporo, Japan  

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Venue：Sapporo, Hokkaido  

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Venue：Sapporo, Japan  

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Venue：東京都江東区  

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Venue：Yokohama, Japan  

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Presentation type：Oral presentation (general)  

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© 2020 SPIE. AMPA-type glutamate receptor (AMPAR) is one of neurotransmitter receptors at excitatory synapses in neuronal cell. For realizing the artificial control of synaptic transmission, we have applied optical trapping of quantum-dot (QD) conjugated AMPARs on neuronal cells. Here, we demonstrate simultaneous measurement combined with optical trapping and patch-clamp recordings to evaluate the neuronal electrical activity. The relationship between optical trapping dynamics of QD-AMPARs located on neuronal cells and the neuronal electrical activity was discussed.

Presentation type：Oral presentation (invited, special)  

Presentation type：Poster presentation  

Presentation type：Poster presentation  

Venue：Osaka  

Presentation type：Poster presentation  

Venue：Ikuta Shrine Hall, Kobe, Japan  

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Presentation type：Oral presentation (invited, special)  

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Venue：大阪市立大学、大阪府大阪市  

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Venue：名古屋大学、愛知県名古屋市  

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Venue：名古屋大学、愛知県名古屋市  

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Venue：Awaji Yumebutai International Conference Center, Awaji Island, Hyogo  

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Venue：大阪府立大学  

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© 2018 OSA - The Optical Society. All rights reserved. Fluorescent imaging is a powerful technique to reveal how target cells or biomolecules work in biological tissues and cells. So far, organic dyes, fluorescent proteins, and quantum dots have been developed and widely used as a fluorescent probe. However, these fluorescent probes do not work well in certain conditions: they have cytotoxicity and steric hindrance due to inclusion of harmful atoms and/or their sizes. Hence, metal nanoclusters, that are composed of several metal atoms and emit fluorescence owing to quantum size effect, have been anticipated as a newly categorized fluorescent probe. Since the fluorescent wavelength depends on their sizes, it is possible to control the fluorescent wavelength by adjusting the number of composed atoms [1].

Presentation type：Oral presentation (invited, special)  

Venue：Tohoku University  

Presentation type：Oral presentation (invited, special)  

Venue：大阪大学  

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Presentation type：Oral presentation (invited, special)  

Venue：大阪府立大学  

Presentation type：Oral presentation (invited, special)  

Presentation type：Oral presentation (general)  

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It's important to investigate natural intelligence how the signal/information is flown in neuronal network. We observed spike trains produced by one-shot electrical stimulation with 8 × 8 multi-electrodes in cultured neuronal networks. Each electrode accepted spikes from several neurons. We then constructed code flow maps as movies of the electrode array to observe the code flow especially of "1101" and "1011." To quantify the flow, we calculated the cross-correlations of the maximum direction of the codes with lengths less than 8. Normalized cross-correlations in the maximum direction were almost constant irrespective of code. Thus, the analysis suggested that the local codes for electrode flow maintained the code shape to some extent and conveyed information in the neural network. Then we made a simulation of such code flow.

Presentation type：Oral presentation (general)  

© 2015 SPIE. Molecular dynamics at synaptic terminals in neuronal cells is essential for synaptic plasticity and subsequent modulation of cellular functions in a neuronal network. For realizing artificial control of living neuronal network, we demonstrate laser-induced perturbation into molecular dynamics in the neuronal cells. The optical trapping of cellular molecules such as synaptic vesicles or neural cell adhesion molecules labeled with quantum dots was evaluated by fluorescence imaging and fluorescence correlation spectroscopy. The trapping and assembling dynamics was revealed that the molecular motion was constrained at the focal spot of a focused laser beam due to optical trapping force. Our method has a potential to manipulate synaptic transmission at single synapse level.

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

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Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Neuron is a simple computational element with rough function, e.g. it cannot receive spikes between refractory period of after it fires. Besides this, its parameters fluctuate time to time. However, as a neuron network they can work intellectually. This gap is an big problem to be solved not only from physiological point of view but also from computer science. We detected pseudo random sequences including M-sequence family in spike trains of cultured neuron network significantly more than by chance. This gave code flow map on multi-electrode array dishes (MED-P515A, Alpha MED Scientific, Kadoma, Osaka, Japan) with 8 × 8 planar microelectrodes. Each electrode catches spikes from several neurons. Conventionally these spike trains are sorted to extract spikes from respective single neuron. Unfortunately but fortunately, however, we obtained mixed neuron spike trains, and by analyzing these, we could find principle of intelligent neuronal network processing.

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

We demonstrated laser manipulation of intracellular molecular dynamics in neurons to realize artificial control toward modulating synaptic transmission in a neuronal network. The optical trapping and assembling dynamics of synaptic vesicles and neural cell adhesion molecules in neurons was revealed by fluorescence analysis. © 2013 IEEE.

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

We have already shown its feasibility by computer simulations that show a loop circuit can be copied to another area by back-propagation leaning algorithm; this is a key function of brain intelligence, which includes functions such as memory, association, reasoning, and abstraction. We also have found M-sequences in spike trains of cultured neuronal networks. In this paper, we report that we found family or fragment of M-sequence responses also in the instantaneous firing rates (PSTH's) from cultured neural networks of published data and our own data, which suggest the existence of loop circuits with a feedback link composed of 3 to 5 neuron cells or equivalent circuits. © 2012 AICIT.

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

We consider that the memory is composed of feedback shift register (FSR) circuit in the cerebral cortex. In this study, we tried to detect M-sequences known as a pseudo random sequence generated by the LFSR circuit from time series patterns of stimulated action potentials of cultured neuronal networks. We could found several M-sequences from a 3-stage LFSR circuit (M3). Then neuronal networks have not a clock control system as a calculator, therefore the bin size of detected M sequences were modulated. We call this phenomenon margin, We tried to test the correlation between margin and number of detected M3. As a result, we found a positive coefficient of correlation.

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

We consider that the memory is composed of loop neural circuit in the cerebral cortex. We have already shown a feasibility of self organization of loop neural circuit for memory, association, and abstraction in our previous study. However, it remains unclear that how the memory is stored and transferred in real neural circuit. In this study, we found pseudo random sequences from cultured neuron networks, which suggest the existence of loop circuit with 3 elements and feedback link.

Presentation type：Oral presentation (general)  

The rat hippocampal neurons were cultured on a dish with 64 planer micro electrodes array. Neurons reorganized a functional network, and an external inputs form outer world elicited a reproducible, particular spatiotemporal pattern of evoked action potentials. The patterns were not completely uniform for repeptive stimulation but varied slightly. We previously reported that dissociated rat hippocampal neurons possessed hysterical function in its network dynamics. The spatio-temporal electrical activity of the living neuronal network evoked by paired stimulation is quite different from one evoked by a single stimulation, suggested that the network can "memorize" an existence of precedent stimulation. In this report, the feature of this type of network hysteresis was investigated and the hysteresis was kept for at least 1s and not kept for 10s. In addition, this hysteresis was remarkable only in aged cultures with matured complex network. Network hysteresis depends on internal state of the network, generated by the autonomous activity in self-organized networks. ©2010 IEEE.

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Quantum dots (QDs) show bright photoluminescence whose emission wavelength can be controlled by their particle size and composition. Compared with organic fluorescent dyes, QDs are more resistant to light irradiation. Because of those advantages, QDs attract much interest as novel bright fluorescent reagents. Photoluminescent QDs are synthesized in solution. However, QDs in solution are not very stable and tend to degradate. Therefore, we developed techniques to incorporate multiple QDs such as CdSe and InP in a small glass bead (diameter: several tens nm) by using sol-gel method at room temperature and under atmospheric pressure. The QD-incorporating glass beads are water-dispersible and emit bright photoluminescence. When dispersed in buffer solution for biological use, the glass beads showed much higher stability and light-resistance than commercial polymer-coated QDs. It was possible to obtain high-resolution fluorescence image of living neuronal cells by introducing the glass beads in the cells by endocytosis.

Presentation type：Oral presentation (general)  

Quantum dots (QDs) show bright photoluminescence whose emission wavelength can be controlled by their particle size and composition. Compared with organic fluorescent dyes, QDs are more resistant to light irradiation. Because of those advantages, QDs attract much interest as novel bright fluorescent reagents. Photoluminescent QDs are synthesized in solution. However, QDs in solution are not very stable and tend to degradate. Therefore, we developed techniques to incorporate multiple QDs such as CdSe and InP in a small glass bead (diameter: several tens nm) by using sol-gel method at room temperature and under atmospheric pressure. The QD-incorporating glass beads are water-dispersible and emit bright photoluminescence. When dispersed in buffer solution for biological use, the glass beads showed much higher stability and light-resistance than commercial polymer-coated QDs. It was possible to obtain high-resolution fluorescence image of living neuronal cells by introducing the glass beads in the cells by endocytosis.

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Rat hippocampal neurons organized complex networks on a culture dish which has 64 planar microelectrodes and the spontaneous action potentials were frequently observed. The living neuronal network was able to distinguish patterns of action potentials evoked by different inputs, suggesting that a cultured neuronal network can represent and process particular states as symbols. We use a Khepera II robot and a robot made by LEGO mindstorm NXT kit as a robot body for interfacing with a living neuronal network and the outer world. We call the system "Vitroid". Vitroid has the living neurons, robot body, and direct coupling type of controllers to interface neurons with the robot. We succeeded in performing obstacle avoidance behavior with premised control rule sets. Using self-tuning fuzzy reasoning, we associated a distinct spatial pattern of electrical activity with a particular phenomenon in the outside of the culture dish. © 2008 IEEE.

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Rat hippocampal neurons organized complex networks on a culture dish which has 64 planner microelectrodes and action potentials of neurons were recorded from an individual electrode. MED64 system, one of multi site recording systems for extracellular action potential was used for recording network activities of living neuronal networks and for applying inputs from outer world to the network. Neurons reconstructed complicated networks along culture days, and a spatio-temporal pattern of spontaneous action potentials was drastically changed after transient high-frequency bursting activities (HFB) . After HFB, spatial distribution of spontaneous action potentials changed to heterogeneous one. We designed programmable multisite stimulation head amplifier, and analysis of evoked action potentials induced by the stimulator confirmed that there are some hub-like structure which has many inputs from other neurons. In addition we are developing "biomodeling system", in which living neuronal network connected to moving robot. ©2007 IEEE.

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

When laser beam was focused into nanoparticle suspensions, nanoparticles can be trapped in the focal spot due to optical gradient force. Here we report the optical trapping and fluorescence analysis of poly(N-isopropylacrylamide) (PNIPAM) and its related polymer microgel particles which were labeled with 4-N-(2-acryloyloxyethyl)-N-methylamino-7-N,N-dimethylaminosulfonyl-2,1, 3-benzoxadiazole (DBD-AE) dispersed in water. The DBD-AE labeled PNIPAM microgel particles were trapped at the focal point by irradiation with cw-Nd 3+:YAG laser (λ = 1064 nm) in water and the fluorescence intensity of the DBD-AE labeled PNIPAM microgel particles excited by diode laser (λ = 405 nm) increased stepwise. We succeeded to fluorescence analysis of trapped single microgel particle.

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (invited, special)