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Author

Noriyoshi Ichikawa

Other affiliations: Gunma University
Bio: Noriyoshi Ichikawa is an academic researcher from Hitachi. The author has contributed to research in topics: Signal & Ordinate. The author has an hindex of 9, co-authored 22 publications receiving 399 citations. Previous affiliations of Noriyoshi Ichikawa include Gunma University.

Papers
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Journal ArticleDOI
TL;DR: The optimum wavelength pair improved the S/N ratio sixfold for deoxyhemoglobin, and new configurations of light irradiation and detection positions doubled the spatial resolution in observations of higher-order brain functions.
Abstract: We will briefly review the present status of optical topography and then discuss the method of improving practicality, i.e., the signal-to-noise (S/N) ratio and the spatial resolution in observations of higher-order brain functions. The optimum wavelength pair improved the S/N ratio sixfold for deoxyhemoglobin, and new configurations of light irradiation and detection positions doubled the spatial resolution. We also report on developing application fields of optical topography. This modality will bridge the gap between natural sciences, neuroscience, and pedagogy, and show actual real-time brain activity.

158 citations

Patent
19 Jul 2002
TL;DR: In this article, a biomedical optical measurement apparatus consisting of a light source unit for generating an inspection light containing multiple lights modulated at different frequencies, a light-receiving unit for receiving the light generated at said light- source unit and passing through an object to be examined and for outputting the electric signals with the intensity corresponding to the received inspection light, and a detection means for detecting a signal with the same frequency of the reference signal in the output from said light receiving unit.
Abstract: A biomedical optical measurement apparatus comprising a light source unit for generating an inspection light containing multiple lights modulated at different frequencies, a light-receiving unit for receiving the light generated at said light source unit and passing through an object to be examined and for outputting the electric signals with the intensity corresponding to the received inspection light, and a detection means for detecting a signal with the same frequency of the reference signal in the output from said light-receiving unit. The detection means comprises an analog-digital conversion means for outputting digitized data by converting an input signal to a digital signal, a storage means for storing digitized data of multiple reference signals, a digital multiplication means for multiplying digitized data of input signals outputted from the analog-digital converting means by the digitized data of the reference signals read out from the storage means and for outputting the product of multiplication, and a digital band-limitation means for taking out DC data from the output from the digital multiplication means. Reference signal generating circuits of a number equal to that of frequencies of detected signals, which has been necessary for the conventional instrument, can be replaced by a single memory means and the configuration of the instrument can be simplified. Changes in frequency can be easily coped with by only re-writing the data of the storing means.

75 citations

Patent
13 Sep 2000
TL;DR: In this paper, a biological light measuring instrument is used to illuminate a subject with a plurality of beams of light from a number of illuminating positions, measuring the light beams transmitted through the subject, and creating a topographic image showing ecological information about the inside of the subject.
Abstract: A biological light measuring instrument for illuminating a subject with a plurality of beams of light from a plurality of illuminating positions, measuring the light beams transmitted through the subject, and creating a topographic image showing ecological information about the inside of the subject, comprising unit for creating three-dimensional coordinate data representing the relationship among the illuminating positions and a reference point on the subject and the relationship between the light measuring position and the reference point, unit for setting the illuminating positions and light measuring position on a three-dimensional shape image of the subject according to the three-dimensional coordinate data, and unit for creating a three-dimensional topographic image according to the three-dimensional coordinate data, and unit for superposing the three-dimensional topographic image on the shape image while maintaining the relationships of the illuminating positions and the light measuring position.

32 citations

Journal ArticleDOI
TL;DR: To estimate the effect of laser exposure on the brain, photon-distribution profiles in bald heads of adults and neonates during the OT were calculated using the photon-diffusion equation, showing that although the absolute values of the intensity depend on details of the head model, the relative values of OT exposure to sunlight exposure were less sensitive to the model details.
Abstract: Optical topography (OT), which is based on the near-infrared spectroscopy, is a powerful tool for observing brain activity noninvasively. To estimate the effect of laser exposure on the brain, photon-distribution profiles in bald heads of adults and neonates during the OT were calculated using the photon-diffusion equation. These calculations showed that although the absolute values of the intensity depend on details of the head model, the relative values of OT exposure to sunlight exposure were less sensitive to the model details. As an example, the light intensities on the brain surface during OT obtained by using a commercially available system were about 2% for adults and 3% for neonates of those values obtained under midday sunlight on a sunny day in midsummer. These values were obtained under the reasonable assumptions with a large safety factor.

26 citations

Patent
01 Nov 2004
TL;DR: In this article, major and independent components of a biosignal obtained by a biological light measurement, e.g. a local brain blood flow variation signal, are analyzed and a plurality of component signals are extracted and displayed.
Abstract: Major and independent components of a biosignal obtained by a biological light measurement, e.g. a local brain blood flow variation signal, are analyzed and a plurality of component signals are extracted and displayed. Out of the component signals, signals except the component signals including a noise are automatically or manually selected. Using the selected signals, the local brain blood flow signal is reconstructed. The reconstructed signal is displayed, subjected to the further analysis of the components and reconstruction in accordance with necessity, and used for analysis of information needed for diagnosis. An outside noise superimposed on the biosignal, particularly, noise that cannot be completely removed by the moving average processing and filtering is reliably removed, thereby obtaining a target signal with high-precision.

24 citations


Cited by
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Journal ArticleDOI
TL;DR: A brief historical overview of the events that have shaped the present status of fNIRS is presented, including the introduction of the commercial multi-channel systems, recent commercial wireless instrumentation and more advanced prototypes.

1,637 citations

Journal ArticleDOI
TL;DR: The aim of this publication is to review the current state of instrumentation and methodology of continuous wave fNIRI, and provides an overview of the commercially available instruments and address instrumental aspects such as light sources, detectors and sensor arrangements.

1,333 citations

Journal ArticleDOI
TL;DR: The current state-of-the-art of diffuse optical imaging is reviewed, which is an emerging technique for functional imaging of biological tissue and recent work on in vivo applications including imaging the breast and brain is reviewed.
Abstract: We review the current state-of-the-art of diffuse optical imaging, which is an emerging technique for functional imaging of biological tissue. It involves generating images using measurements of visible or near-infrared light scattered across large (greater than several centimetres) thicknesses of tissue. We discuss recent advances in experimental methods and instrumentation, and examine new theoretical techniques applied to modelling and image reconstruction. We review recent work on in vivo applications including imaging the breast and brain, and examine future challenges.

1,237 citations

Journal ArticleDOI
TL;DR: Advances currently being made and issues to consider for improving optical image quality include the optimal selection of wavelengths to minimize random and systematic error propagation in the calculation of the hemoglobin concentrations.

722 citations

Journal ArticleDOI
TL;DR: A novel registration method, based on simulations in place of physical measurements for optode positioning, that allowed the spatial registration of completely stand-alone fNIRS data onto MNI space without the use of supplementary measurements.

503 citations