医用データ科学

Hidetoshi Urakubo

  (浦久保 秀俊)

Profile Information

Affiliation
Associate professor, Department of Biomedical Data Science, School of Medicine, Fujita Health University
Degree
Ph.D(Mar, 2003, Univresity of Tokyo)

Researcher number
40512140
J-GLOBAL ID
201101036451836391
researchmap Member ID
B000004615

External link

Reflected in our thoughts,
experience, by reforming our actions,
nurtures our well-being.

 

Motivated by an interest in the memorization mechanisms of the brain, I have conducted computer simulations to investigate whether current knowledge about molecular neuroscience provides a synaptic basis for learning and memory—that is, whether synaptic plasticity underlies the brain’s ability to learn and remember. My research goal is the derivation of mathematical models of synaptic plasticity. The rules of synaptic plasticity are not simple. Synaptic plasticity generally occurs in a synapse-specific manner, but in some case it occurs cooperatively among synapses. It is also significantly affected by age, emotional state, and psychiatric disorders. I focus on the first steps of how neural functions emerge from complex biochemical reactions at synapses. (more)


Committee Memberships

 1

Awards

 1

Papers

 25
  • Takayuki Onai, Noritaka Adachi, Hidetoshi Urakubo, Fumiaki Sugahara, Toshihiro Aramaki, Mami Matsumoto, Nobuhiko Ohno
    iScience, 108338-108338, Nov, 2023  Peer-reviewed
  • Sergey Mursalimov, Mami Matsumoto, Hidetoshi Urakubo, Elena Deineko, Nobuhiko Ohno
    Annals of Botany, mcad107, Jul 25, 2023  Peer-reviewed
    Abstract Background and Aims During the analysis of plant male meiocytes coming from destroyed meiocyte columns (united multicellular structures formed by male meiocytes in each anther locule), a considerable amount of information becomes unavailable. Therefore, in this study intact meiocyte columns were studied by volume microscopy in wild-type rye for the most relevant presentation of 3-D structure of rye meiocytes throughout meiosis. Methods We used two types of volume light microscopy: confocal laser scanning microscopy and non-confocal bright-field scanning microscopy combined with alcohol and aldehyde fixation, as well as serial block-face scanning electron microscopy. Key Results Unusual structures, called nuclear protuberances, were detected. At certain meiotic stages, nuclei formed protuberances that crossed the cell wall through intercellular channels and extended into the cytoplasm of neighbouring cells, while all other aspects of cell structure appeared to be normal. This phenomenon of intercellular nuclear migration (INM) was detected in most meiocytes at leptotene/zygotene. No cases of micronucleus formation or appearance of binucleated meiocytes were noticed. There were instances of direct contact between two nuclei during INM. No influence of fixation or of mechanical impact on the induction of INM was detected. Conclusions Intercellular nuclear migration in rye may be a programmed process (a normal part of rye male meiosis) or a tricky artefact that cannot be avoided in any way no matter which approach to meiocyte imaging is used. In both cases, INM seems to be an obligatory phenomenon that has previously been hidden by limitations of common microscopic techniques and by 2-D perception of plant male meiocytes. Intercellular nuclear migration cannot be ignored in any studies involving manipulations of rye anthers.
  • Sehyung Lee, Hideaki Kume, Hidetoshi Urakubo, Haruo Kasai, Shin Ishii
    Neural networks, 152 57-69, Aug, 2022  Peer-reviewed
  • Hidetoshi Urakubo, Sho Yagishita, Haruo Kasai, Yoshiyuki Kubota, Shin Ishii
    PLOS Computational Biology, 17(9) e1009364-e1009364, Sep 30, 2021  Peer-reviewedLead authorCorresponding author
    In behavioral learning, reward-related events are encoded into phasic dopamine (DA) signals in the brain. In particular, unexpected reward omission leads to a phasic decrease in DA (DA dip) in the striatum, which triggers long-term potentiation (LTP) in DA D2 receptor (D2R)-expressing spiny-projection neurons (D2 SPNs). While this LTP is required for reward discrimination, it is unclear how such a short DA-dip signal (0.5–2 s) is transferred through intracellular signaling to the coincidence detector, adenylate cyclase (AC). In the present study, we built a computational model of D2 signaling to determine conditions for the DA-dip detection. The DA dip can be detected only if the basal DA signal sufficiently inhibits AC, and the DA-dip signal sufficiently disinhibits AC. We found that those two requirements were simultaneously satisfied only if two key molecules, D2R and regulators of G protein signaling (RGS) were balanced within a certain range; this balance has indeed been observed in experimental studies. We also found that high level of RGS was required for the detection of a 0.5-s short DA dip, and the analytical solutions for these requirements confirmed their universality. The imbalance between D2R and RGS is associated with schizophrenia and DYT1 dystonia, both of which are accompanied by abnormal striatal LTP. Our simulations suggest that D2 SPNs in patients with schizophrenia and DYT1 dystonia cannot detect short DA dips. We finally discussed that such psychiatric and movement disorders can be understood in terms of the imbalance between D2R and RGS.
  • Laxmi Kumar Parajuli, Hidetoshi Urakubo, Ai Takahashi-Nakazato, Roberto Ogelman, Hirohide Iwasaki, Masato Koike, Hyung-Bae Kwon, Shin Ishii, Won Chan Oh, Yugo Fukazawa, Shigeo Okabe
    eNeuro, Oct 27, 2020  Peer-reviewed
    Precise information on synapse organization in a dendrite is crucial to understanding the mechanisms underlying voltage integration and the variability in the strength of synaptic inputs across dendrites of different complex morphologies. Here, we used focused ion beam/scanning electron microscope (FIB/SEM) to image the dendritic spines of mice in the hippocampal CA1 region, CA3 region, somatosensory cortex, striatum, and cerebellum (CB). Our results show that the spine geometry and dimensions differ across neuronal cell types. Despite this difference, dendritic spines were organized in an orchestrated manner such that the postsynaptic density (PSD) area per unit length of dendrite scaled positively with the dendritic diameter in CA1 proximal stratum radiatum (PSR), cortex and CB. The ratio of the PSD area to neck length was kept relatively uniform across dendrites of different diameters in CA1 PSR. Computer simulation suggests that a similar level of synaptic strength across different dendrites in CA1 PSR enables the effective transfer of synaptic inputs from the dendrites towards soma. Excitatory postsynaptic potentials (EPSPs), evoked at single spines by glutamate uncaging and recorded at the soma, show that the neck length is more influential than head width in regulating the EPSP magnitude at the soma. Our study describes thorough morphological features and the organizational principles of dendritic spines in different brain regions.Significance statement Little is known about the characteristic anatomical features underlying the organization of spine synapses in a dendrite. This study used volume electron microscopy to make an extensive characterization of dendritic spine synapses in multiple regions of the mouse brain to uncover the principles underlying their placement along a dendritic shaft. By using a combination of approaches such as two-photon imaging, glutamate uncaging, electrophysiology, and computer simulation, we reveal the functional importance of regulated spine placement along a dendritic trunk. Our research presents a crucial step in understanding the synaptic computational principle in dendrites by highlighting the generalizable features of dendritic spine organization in a neuron.

Misc.

 26

Teaching Experience

 6

Research Projects

 9