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89 results on '"Nomura, Masaki"'

51. Functional effects of distinct innervation styles of pyramidal cells by fast spiking cortical interneurons

Author

Kubota, Yoshiyuki, Kondo, Satoru, Nomura, Masaki, Hatada, Sayuri, Yamaguchi, Noboru, Mohamed, Alsayed A., Karube, Fuyuki, Lübke, Joachim, Kawaguchi, Yasuo, Kubota, Yoshiyuki, Kondo, Satoru, Nomura, Masaki, Hatada, Sayuri, Yamaguchi, Noboru, Mohamed, Alsayed A., Karube, Fuyuki, Lübke, Joachim, and Kawaguchi, Yasuo

Abstract

Inhibitory interneurons target precise membrane regions on pyramidal cells, but differences in their functional effects on somata, dendrites and spines remain unclear. We analyzed inhibitory synaptic events induced by cortical, fast-spiking (FS) basket cells which innervate dendritic shafts and spines as well as pyramidal cell somata. Serial electron micrograph (EMg) reconstructions showed that somatic synapses were larger than dendritic contacts. Simulations with precise anatomical and physiological data reveal functional differences between different innervation styles. FS cell soma-targeting synapses initiate a strong, global inhibition, those on shafts inhibit more restricted dendritic zones, while synapses on spines may mediate a strictly local veto. Thus, FS cell synapses of different sizes and sites provide functionally diverse forms of pyramidal cell inhibition.

Published
2015

82. Induction of the biosynthesis of agatharesinol, a norlignan, in sapwood sticks of Cryptomeria japonicaunder humidity-regulated circumstances

Author

Imai, Takanori and Nomura, Masaki

Abstract

To establish an experimental approach for studying the biosynthetic pathway of agatharesinol, a norlignan, induction of the formation of agatharesinol in Cryptomeria japonica(Japanese cedar, sugi) was attempted. Wood sticks were prepared from the sapwood immediately after cutting a sugi tree down, and they were allowed to stand in desiccators in which the humidity was adjusted to 76% and 88%, and in a room. When the wood sticks were allowed to stand in 76% humidity and in a room, they dried rapidly and no formation of agatharesinol was demonstrated by gas chromatography-mass spectrometry. These results suggest that in the sapwood dried rapidly, the cells that were biologically active in the sapwood, probably ray parenchyma cells, die rapidly and completely before the biosyntheses of secondary metabolites including agatharesinol was wholly established. The wood sticks allowed to stand in 88% humidity, on the other hand, dried gradually compared with the sticks placed in 76% humidity and in a room, and agatharesinol was formed as one of the predominant ethyl acetate extractives. These results suggest that delaying the drying of the sapwood sticks can control the dying period to an appropriate length for the ray parenchyma cells, during which the biosynthesis of agatharesinol is induced.

Published
2005
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87. Phase Analysis of Inhibitory Neurons Involved in the Thalamocortical Loop

Author

Nomura, Masaki, Tanaka, Takuma, Kaneko, Takeshi, and Aoyagi, Toshio

Abstract

We examined the synchronous-asynchronous spiking behavior of weakly coupled two neurons using an analytic theory called “phase-reduction method”. By modeling neurons involved in the thalamocortical loop, we show how the form of phase-response function depends on ion channels specific to each neuron model. Next, we investigate the synchronous-asynchronous spiking behavior of a pair of identical neurons interconnected by a gap junction or a reciprocal inhibitory synapse.

Published
2013
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88. Stability of Synchronous Solutions in Weakly Coupled Neuron Networks

Author

Nomura, Masaki and Aoyagi, Toshio

Abstract

The stability of synchronous solutions for weakly coupled two-neuron networks is examined. It is well known that for a pair of identical neurons with a weak, reciprocal connection, there always exists a synchronous solution, the stability of which depends on both intrinsic cell properties and the connection type. By considering several neuronal models, all of which possess a Type-I phase-response function, the manners in which the form of the phase-response function and the neuronal coupling affect the stability of the synchronous solution are investigated, and the properties necessary for stable synchrony in these models are described in detail.

Published
2005
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89. [Steroid receptor superfamily and its mechanism of action].

Author

Nawata H, Yanase T, Okabe T, and Nomura M

Subjects
Receptor Cross-Talk physiology, Receptors, Cytoplasmic and Nuclear classification, Receptors, Steroid classification, Receptors, Steroid physiology
Abstract

Steroid receptors are evoluted from the common ancestor and have the same structure as steroid receptor superfamily. The nuclear receptors are characterized by a central DNA binding domain with specific DNA sequences known as hormone response element, ligand binding domain in the C terminal and N terminal domain with the tissue specificity. Nuclear receptor superfamily is divided into four classes based on the dimerization and DNA binding properties, homodimers as steroid hormone receptor, heterodimers with RXR, homodimers and monomers. Most of orphan receptors fall into the last 2 classes. The coregulators as coactivators and corepressor are determined. The mechanism of action of nuclear receptor on chromatin in the nucleus are clarified precisely from the stand point of the clasters of coregulators and the complex of nuclear receptor and coregulators. The crosstalk of nuclear receptor and peptide hormone signal in the cell is important in the autocrine and paracrine action. Non-genomic action of steroid hormone is also proposed.

Published
2008

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