The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform

Tetsuya Yagi - One of the best experts on this subject based on the ideXlab platform.

  • BioCAS - A programmable controller for spatio-temporal Pattern Stimulation of cortical visual prosthesis
    2016 IEEE Biomedical Circuits and Systems Conference (BioCAS), 2016
    Co-Authors: Tomoki Sugiura, Arif Ullah Khan, Jaehoon Yu, Yoshinori Takeuchi, Seiji Kameda, Takatsugu Kamata, Yuki Hayashida, Tetsuya Yagi, Masaharu Imai
    Abstract:

    This paper proposes a programmable Stimulation controller for cortical visual prosthesis to configure spatio-temporal parameters of Stimulation. Since the relationship between Stimulation to the visual cortex and responses in vision has not been clarified enough both flexibility for Stimulation strategies and timewise precision of Stimulation are required for in-vivo experiments. In the proposed Stimulation controller a 16bit microprocessor is utilized for various Stimulation strategies and dedicated control signal generator for electrodes runs in parallel with the microprocessor. The proposed Stimulation controller generates Stimulations in temporal resolution of 1 yus and spatio resolution up to 4 096 Stimulation sites. Evaluation with an FPGA demonstrates the programmability of its implementation.

  • A programmable controller for spatio-temporal Pattern Stimulation of cortical visual prosthesis
    2016 IEEE Biomedical Circuits and Systems Conference (BioCAS), 2016
    Co-Authors: Tomoki Sugiura, Arif Ullah Khan, Jaehoon Yu, Yoshinori Takeuchi, Seiji Kameda, Takatsugu Kamata, Yuki Hayashida, Tetsuya Yagi, Masaharu Imai
    Abstract:

    This paper proposes a programmable Stimulation controller for cortical visual prosthesis to configure spatiotemporal parameters of Stimulation. Since the relationship between Stimulation to the visual cortex and responses in vision has not been clarified enough, both flexibility for Stimulation strategies and timewise precision of Stimulation are required for in-vivo experiments. In the proposed Stimulation controller, a 16-bit microprocessor is utilized for various Stimulation strategies, and dedicated control signal generator for electrodes runs in parallel with the microprocessor. The proposed Stimulation controller generates Stimulations in temporal resolution of 1 μs and spatio resolution up to 4 096 Stimulation sites. Evaluation with an FPGA demonstrates the programmability of its implementation.

  • EMBC - A multichannel current stimulator chip for spatiotemporal Pattern Stimulation of neural tissues.
    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and, 2014
    Co-Authors: Seiji Kameda, Yuki Hayashida, Yuta Tanaka, Dai Akita, Tetsuya Yagi
    Abstract:

    : We developed a prototype very-large-scale integration chip of a multichannel current stimulator for stimulating neural tissues by utilizing 0.25 μm high-voltage complementary metal-oxide-semiconductor technology. Our designed chip has 20 output channels that are driven by five current buffers arranged in parallel; each buffer controls four output channels in time-sharing mode. The amplitude of a Stimulation pulse can be controlled within a range of approximately ±100 μA/phase in each output channel. The stimulus parameters, e.g., amplitude and duration, are controlled separately for each channel by digital codes stored in built-in registers. Combinations of anode and cathode electrodes to pass the current can be changed online. We integrated our stimulator chip with a multielectrode array and studied the neuronal responses to multichannel current Stimulations with various temporal Patterns in mouse brain slices.

  • A multichannel current stimulator chip for spatiotemporal Pattern Stimulation of neural tissues
    2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014
    Co-Authors: Seiji Kameda, Yuki Hayashida, Yuta Tanaka, Dai Akita, Tetsuya Yagi
    Abstract:

    We developed a prototype very-large-scale integration chip of a multichannel current stimulator for stimulating neural tissues by utilizing 0.25 μm high-voltage complementary metal-oxide-semiconductor technology. Our designed chip has 20 output channels that are driven by five current buffers arranged in parallel; each buffer controls four output channels in time-sharing mode. The amplitude of a Stimulation pulse can be controlled within a range of approximately ±100 μA/phase in each output channel. The stimulus parameters, e.g., amplitude and duration, are controlled separately for each channel by digital codes stored in built-in registers. Combinations of anode and cathode electrodes to pass the current can be changed online. We integrated our stimulator chip with a multielectrode array and studied the neuronal responses to multichannel current Stimulations with various temporal Patterns in mouse brain slices.

Seiji Kameda - One of the best experts on this subject based on the ideXlab platform.

  • BioCAS - A programmable controller for spatio-temporal Pattern Stimulation of cortical visual prosthesis
    2016 IEEE Biomedical Circuits and Systems Conference (BioCAS), 2016
    Co-Authors: Tomoki Sugiura, Arif Ullah Khan, Jaehoon Yu, Yoshinori Takeuchi, Seiji Kameda, Takatsugu Kamata, Yuki Hayashida, Tetsuya Yagi, Masaharu Imai
    Abstract:

    This paper proposes a programmable Stimulation controller for cortical visual prosthesis to configure spatio-temporal parameters of Stimulation. Since the relationship between Stimulation to the visual cortex and responses in vision has not been clarified enough both flexibility for Stimulation strategies and timewise precision of Stimulation are required for in-vivo experiments. In the proposed Stimulation controller a 16bit microprocessor is utilized for various Stimulation strategies and dedicated control signal generator for electrodes runs in parallel with the microprocessor. The proposed Stimulation controller generates Stimulations in temporal resolution of 1 yus and spatio resolution up to 4 096 Stimulation sites. Evaluation with an FPGA demonstrates the programmability of its implementation.

  • A programmable controller for spatio-temporal Pattern Stimulation of cortical visual prosthesis
    2016 IEEE Biomedical Circuits and Systems Conference (BioCAS), 2016
    Co-Authors: Tomoki Sugiura, Arif Ullah Khan, Jaehoon Yu, Yoshinori Takeuchi, Seiji Kameda, Takatsugu Kamata, Yuki Hayashida, Tetsuya Yagi, Masaharu Imai
    Abstract:

    This paper proposes a programmable Stimulation controller for cortical visual prosthesis to configure spatiotemporal parameters of Stimulation. Since the relationship between Stimulation to the visual cortex and responses in vision has not been clarified enough, both flexibility for Stimulation strategies and timewise precision of Stimulation are required for in-vivo experiments. In the proposed Stimulation controller, a 16-bit microprocessor is utilized for various Stimulation strategies, and dedicated control signal generator for electrodes runs in parallel with the microprocessor. The proposed Stimulation controller generates Stimulations in temporal resolution of 1 μs and spatio resolution up to 4 096 Stimulation sites. Evaluation with an FPGA demonstrates the programmability of its implementation.

  • EMBC - A multichannel current stimulator chip for spatiotemporal Pattern Stimulation of neural tissues.
    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and, 2014
    Co-Authors: Seiji Kameda, Yuki Hayashida, Yuta Tanaka, Dai Akita, Tetsuya Yagi
    Abstract:

    : We developed a prototype very-large-scale integration chip of a multichannel current stimulator for stimulating neural tissues by utilizing 0.25 μm high-voltage complementary metal-oxide-semiconductor technology. Our designed chip has 20 output channels that are driven by five current buffers arranged in parallel; each buffer controls four output channels in time-sharing mode. The amplitude of a Stimulation pulse can be controlled within a range of approximately ±100 μA/phase in each output channel. The stimulus parameters, e.g., amplitude and duration, are controlled separately for each channel by digital codes stored in built-in registers. Combinations of anode and cathode electrodes to pass the current can be changed online. We integrated our stimulator chip with a multielectrode array and studied the neuronal responses to multichannel current Stimulations with various temporal Patterns in mouse brain slices.

  • A multichannel current stimulator chip for spatiotemporal Pattern Stimulation of neural tissues
    2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014
    Co-Authors: Seiji Kameda, Yuki Hayashida, Yuta Tanaka, Dai Akita, Tetsuya Yagi
    Abstract:

    We developed a prototype very-large-scale integration chip of a multichannel current stimulator for stimulating neural tissues by utilizing 0.25 μm high-voltage complementary metal-oxide-semiconductor technology. Our designed chip has 20 output channels that are driven by five current buffers arranged in parallel; each buffer controls four output channels in time-sharing mode. The amplitude of a Stimulation pulse can be controlled within a range of approximately ±100 μA/phase in each output channel. The stimulus parameters, e.g., amplitude and duration, are controlled separately for each channel by digital codes stored in built-in registers. Combinations of anode and cathode electrodes to pass the current can be changed online. We integrated our stimulator chip with a multielectrode array and studied the neuronal responses to multichannel current Stimulations with various temporal Patterns in mouse brain slices.

Yuki Hayashida - One of the best experts on this subject based on the ideXlab platform.

  • BioCAS - A programmable controller for spatio-temporal Pattern Stimulation of cortical visual prosthesis
    2016 IEEE Biomedical Circuits and Systems Conference (BioCAS), 2016
    Co-Authors: Tomoki Sugiura, Arif Ullah Khan, Jaehoon Yu, Yoshinori Takeuchi, Seiji Kameda, Takatsugu Kamata, Yuki Hayashida, Tetsuya Yagi, Masaharu Imai
    Abstract:

    This paper proposes a programmable Stimulation controller for cortical visual prosthesis to configure spatio-temporal parameters of Stimulation. Since the relationship between Stimulation to the visual cortex and responses in vision has not been clarified enough both flexibility for Stimulation strategies and timewise precision of Stimulation are required for in-vivo experiments. In the proposed Stimulation controller a 16bit microprocessor is utilized for various Stimulation strategies and dedicated control signal generator for electrodes runs in parallel with the microprocessor. The proposed Stimulation controller generates Stimulations in temporal resolution of 1 yus and spatio resolution up to 4 096 Stimulation sites. Evaluation with an FPGA demonstrates the programmability of its implementation.

  • A programmable controller for spatio-temporal Pattern Stimulation of cortical visual prosthesis
    2016 IEEE Biomedical Circuits and Systems Conference (BioCAS), 2016
    Co-Authors: Tomoki Sugiura, Arif Ullah Khan, Jaehoon Yu, Yoshinori Takeuchi, Seiji Kameda, Takatsugu Kamata, Yuki Hayashida, Tetsuya Yagi, Masaharu Imai
    Abstract:

    This paper proposes a programmable Stimulation controller for cortical visual prosthesis to configure spatiotemporal parameters of Stimulation. Since the relationship between Stimulation to the visual cortex and responses in vision has not been clarified enough, both flexibility for Stimulation strategies and timewise precision of Stimulation are required for in-vivo experiments. In the proposed Stimulation controller, a 16-bit microprocessor is utilized for various Stimulation strategies, and dedicated control signal generator for electrodes runs in parallel with the microprocessor. The proposed Stimulation controller generates Stimulations in temporal resolution of 1 μs and spatio resolution up to 4 096 Stimulation sites. Evaluation with an FPGA demonstrates the programmability of its implementation.

  • EMBC - A multichannel current stimulator chip for spatiotemporal Pattern Stimulation of neural tissues.
    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and, 2014
    Co-Authors: Seiji Kameda, Yuki Hayashida, Yuta Tanaka, Dai Akita, Tetsuya Yagi
    Abstract:

    : We developed a prototype very-large-scale integration chip of a multichannel current stimulator for stimulating neural tissues by utilizing 0.25 μm high-voltage complementary metal-oxide-semiconductor technology. Our designed chip has 20 output channels that are driven by five current buffers arranged in parallel; each buffer controls four output channels in time-sharing mode. The amplitude of a Stimulation pulse can be controlled within a range of approximately ±100 μA/phase in each output channel. The stimulus parameters, e.g., amplitude and duration, are controlled separately for each channel by digital codes stored in built-in registers. Combinations of anode and cathode electrodes to pass the current can be changed online. We integrated our stimulator chip with a multielectrode array and studied the neuronal responses to multichannel current Stimulations with various temporal Patterns in mouse brain slices.

  • A multichannel current stimulator chip for spatiotemporal Pattern Stimulation of neural tissues
    2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014
    Co-Authors: Seiji Kameda, Yuki Hayashida, Yuta Tanaka, Dai Akita, Tetsuya Yagi
    Abstract:

    We developed a prototype very-large-scale integration chip of a multichannel current stimulator for stimulating neural tissues by utilizing 0.25 μm high-voltage complementary metal-oxide-semiconductor technology. Our designed chip has 20 output channels that are driven by five current buffers arranged in parallel; each buffer controls four output channels in time-sharing mode. The amplitude of a Stimulation pulse can be controlled within a range of approximately ±100 μA/phase in each output channel. The stimulus parameters, e.g., amplitude and duration, are controlled separately for each channel by digital codes stored in built-in registers. Combinations of anode and cathode electrodes to pass the current can be changed online. We integrated our stimulator chip with a multielectrode array and studied the neuronal responses to multichannel current Stimulations with various temporal Patterns in mouse brain slices.

Folkert K. Horn - One of the best experts on this subject based on the ideXlab platform.

  • pupillographic measurements with Pattern Stimulation the pupil s response in normal subjects and first measurements in glaucoma patients
    Investigative Ophthalmology & Visual Science, 2006
    Co-Authors: Barbara Link, Anselm Jünemann, Otto Sembritzki, Alexander Brenning, Matthias Korth, Folkert K. Horn
    Abstract:

    PURPOSE. This study was undertaken to characterize the influence of contrast, luminance, and spatial frequency of a Pattern stimulus on the pupil reaction of healthy subjects. First measurements with this technique in patients with glaucoma were compared with those in a control group. METHOD. Grating Patterns were presented using a Maxwellianview system to study series of contrast, luminance, and spatial frequency in three healthy subjects. The best two stimulus conditions were determined and were then used to examine 19 patients with open-angle glaucoma and 16 control subjects. RESULTS. In healthy subjects, an increasing contrast led to an increase in amplitude and a decrease in latency of the pupil reflex. Increasing luminance also resulted in an increase in the amplitude. The offset component of the pupil reflex was most pronounced at low spatial frequencies and the onset component at high spatial frequencies. When healthy subjects were compared with patients with glaucoma, control subjects generally had higher amplitudes, velocity, and acceleration of pupil constriction than did the patients with glaucoma. These differences were significant when the test was performed with a spatial frequency of 6.25 cyc/deg. CONCLUSIONS. Best stimulus conditions to elicit a pupil response to a Pattern grating stimulus are 100% contrast and 55 cd/m 2 mean luminance. The choice of the spatial frequency determines which component of the pupil reflex is more pronounced. Differences between patients with glaucoma and healthy control subjects are demonstrable. (Invest Ophthalmol Vis Sci. 2006;47:4947‐4955) DOI:10.1167/iovs.06-0021

  • Pattern Reversal ERG and VEP – Comparison of Stimulation by LED, Monitor and a Maxwellian-view System
    Documenta Ophthalmologica, 2006
    Co-Authors: Barbara Link, Sylvia Rühl, Andrea Peters, Anselm Jünemann, Folkert K. Horn
    Abstract:

    Purpose: Pattern Stimulation is widely used to detect inner retinal dysfunction. In this work we describe a Pattern Stimulation technique with LEDs and compare the results with conventional methods. Methods: PERG and VEP were derived from three normal subjects. Three different techniques were used to generate a checkerboard Pattern reversal stimulus: a 70 Hz monitor, a Maxwellian-view system equipped with a Xenon-arc lamp and a mechanical mirror system, and a LED array (Roland Consult) consisting of 100 white LEDs. Two kinds of luminance (125 and 340 cd/m^2) and four temporal frequencies (4, 8, 12 and 24 reversals per second) were studied on three healthy subjects. Additionally, a luminance tuning experiment (30, 60, 90, 125 and 340 cd/m^2) was performed on one subject. Results: Comparison of different Stimulation techniques shows reproducible responses of PERG and VEP with all three methods. The LED array leads to slightly smaller amplitudes than both other techniques, which we ascribe to the design of the LED field. No difference of peak times or phases was noticed between different Stimulation techniques. A luminance dependency of PERG and VEP is noticeable using Stimulation with LED: with decreasing luminance we measured increasing peak times of PERG and VEP and decreasing amplitude of PERG. Conclusion: We conclude that central retinal Stimulation with checkerboard Pattern reversal is possible with LED. It gives comparable results to monitor and Maxwellian-view system.

  • Pattern reversal erg and vep comparison of Stimulation by led monitor and a maxwellian view system
    Documenta Ophthalmologica, 2006
    Co-Authors: Barbara Link, Sylvia Rühl, Andrea Peters, Anselm Jünemann, Folkert K. Horn
    Abstract:

    Purpose: Pattern Stimulation is widely used to detect inner retinal dysfunction. In this work we describe a Pattern Stimulation technique with LEDs and compare the results with conventional methods. Methods: PERG and VEP were derived from three normal subjects. Three different techniques were used to generate a checkerboard Pattern reversal stimulus: a 70 Hz monitor, a Maxwellian-view system equipped with a Xenon-arc lamp and a mechanical mirror system, and a LED array (Roland Consult) consisting of 100 white LEDs. Two kinds of luminance (125 and 340 cd/m2) and four temporal frequencies (4, 8, 12 and 24 reversals per second) were studied on three healthy subjects. Additionally, a luminance tuning experiment (30, 60, 90, 125 and 340 cd/m2) was performed on one subject. Results: Comparison of different Stimulation techniques shows reproducible responses of PERG and VEP with all three methods. The LED array leads to slightly smaller amplitudes than both other techniques, which we ascribe to the design of the LED field. No difference of peak times or phases was noticed between different Stimulation techniques. A luminance dependency of PERG and VEP is noticeable using Stimulation with LED: with decreasing luminance we measured increasing peak times of PERG and VEP and decreasing amplitude of PERG. Conclusion: We conclude that central retinal Stimulation with checkerboard Pattern reversal is possible with LED. It gives comparable results to monitor and Maxwellian-view system.

Yasuhiko Jimbo - One of the best experts on this subject based on the ideXlab platform.

  • Change in Evoked Response of Mature Neuronal Network to Spatial Pattern Stimulation by Immature Neurons
    2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2019
    Co-Authors: Fumika Moriya, Kenta Shimba, Kiyoshi Kotani, Yasuhiko Jimbo
    Abstract:

    Adult neurogenesis in the hippocampus is known to enhance Pattern separation. However, the effect of adult neurogenesis on spatial Pattern separation at the cellular assembly level is unclear. In order to elucidate how newborn and immature neurons change learning of spatial Pattern of mature neuronal network, we evaluated evoked response to two types of spatial Patterns of the cultured hippocampal network with or without added neural stem cells by using electrical Stimulation on microelectrode array. Results show that the existence of newborn and immature neurons changed evoked response of mature neuronal network to both trained and untrained Patterns, suggesting that the presence of immature neurons may contribute to production of the change that mature neuronal network enhances LTP and excitation to stimuli.

  • EMBC - Change in Evoked Response of Mature Neuronal Network to Spatial Pattern Stimulation by Immature Neurons
    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and, 2019
    Co-Authors: Fumika Moriya, Kenta Shimba, Kiyoshi Kotani, Yasuhiko Jimbo
    Abstract:

    Adult neurogenesis in the hippocampus is known to enhance Pattern separation. However, the effect of adult neurogenesis on spatial Pattern separation at the cellular assembly level is unclear. In order to elucidate how newborn and immature neurons change learning of spatial Pattern of mature neuronal network, we evaluated evoked response to two types of spatial Patterns of the cultured hippocampal network with or without added neural stem cells by using electrical Stimulation on microelectrode array. Results show that the existence of newborn and immature neurons changed evoked response of mature neuronal network to both trained and untrained Patterns, suggesting that the presence of immature neurons may contribute to production of the change that mature neuronal network enhances LTP and excitation to stimuli.

  • Neurogenesis Enhances Response Specificity to Spatial Pattern Stimulation in Hippocampal Cultures
    IEEE Transactions on Biomedical Engineering, 2017
    Co-Authors: Yukimi Tanaka, Takuya Isomura, Kenta Shimba, Kiyoshi Kotani, Yasuhiko Jimbo
    Abstract:

    Objective: Adult neurogenesis in the hippocampus facilitates cognitive functions such as Pattern separation in mammals. However, it remains unclear how newborn neurons mediate changes in neural networks to enhance the Pattern separation ability. Here, we developed an in vitro model of adult neurogenesis using rat hippocampal cultures in order to investigate whether newborn neurons can be directly incorporated into neural networks related to Pattern separation to produce functional improvements. Method: We optimized at schedule of basic fibroblast growth factor (bFGF) administration to enhance neurogenesis, and then used a microelectrode array system to evaluate the responses of neural cultures to two different spatial Pattern stimuli (L and inverted L shapes) before and after training. Results: We found that early synaptic response times to a given Pattern were shortened after training, and that this effect was more pronounced in cultures treated with bFGF. Furthermore, bFGF-treated cultures showed improved response specificity after training as indicated by calculated Kullback-Leibler divergence values, suggesting that Pattern separation was better achieved in cultures with enhanced neurogenesis. Conclusion: Neural networks containing greater numbers of immature neurons exhibited higher response specificity to spatial Pattern Stimulation, suggesting the improvement of the Pattern separation by neurogenesis enhancement. Significance: These results are the first in vitro demonstration that neurogenesis improves Pattern separation. Our novel in vitro system will be a useful tool for investigating the contribution of adult neurogenesis to cognitive functions.