Publications by authors named "Naoki Kotake"

The inferior temporal cortex (ITC) contains neurons selective to multiple levels of visual categories. However, the mechanisms by which these neurons collectively construct hierarchical category percepts remain unclear. By comparing decoding accuracy with simultaneously acquired electrocorticogram (ECoG), local field potentials (LFPs), and multi-unit activity in the macaque ITC, we show that low-frequency LFPs/ECoG in the early evoked visual response phase contain sufficient coarse category (e.

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We present a simple method to regulate the direction of axon development in cultured neurons using microfabrication and microfluidics techniques. We fabricate a PDMS-based device and place it onto a chemically micropatterned glass substrate. We confirm that cultured neurons extend neurites along the medium flow direction and the micropatterned regions.

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The cultured neuronal monolayer has been a promising model system for studying the neuronal dynamics, from single cell to network-wide level. Randomness in the reconstituted network structure has, however, hindered regulated signal transmissions from one neuron to another or from one neuronal population to another. Applying microfabrication-based cell patterning techniques is a promising approach to handling these problems.

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Heat-shock protein90 (HSP90) plays an essential role in maintaining stability and activity of its clients. HSP90 is involved in cell differentiation and survival in a variety of cell types. To elucidate the possible role of HSP90 in myogenic differentiation and cell survival, we examined the time course of changes in the expression of myogenic regulatory factors, intracellular signaling molecules, and anti-/pro-apoptotic factors when C2C12 cells were cultured in differentiation condition in the presence of a HSP90-specific inhibitor, geldanamycin.

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The abundance, morphology, and functional properties of mitochondria become altered in response to denervation. To gain insight into the regulation of this process, mitochondrial enzyme activities and gene expression involved in mitochondrial biogenesis and dynamics in mouse gastrocnemius muscle was investigated. Sciatic nerve transactions were performed on mice, and then gastrocnemius muscles were isolated at days 5 and 30 after surgery.

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To gain insight into the regulation of mitochondrial adaptations to hindlimb unloading (HU), the activity of mitochondrial enzymes and the expression of nuclear-encoded genes which control mitochondrial properties in mouse gastrocnemius muscle were investigated. Biochemical and enzyme histochemical analysis showed that subsarcolemmal mitochondria were lost largely than intermyofibrillar mitochondria after HU. Gene expression analysis revealed disturbed or diminished gene expression patterns.

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We investigated the expression of the nuclear-encoded genes controlling the mitochondrial properties in the mouse gastrocnemius muscle to gain insight into the mitochondrial biogenesis that occurs during the muscle degeneration/regeneration induced by freezing. In addition, we tested whether the muscle regeneration is affected by pharmacologically blocking the mitochondrial protein synthesis to elucidate the possible involvement of mitochondrial biogenesis in muscle regeneration. The activity of citrate synthase dramatically increased soon after the initial injury when the myoblasts began to differentiate into myotubes, indicating that mitochondrial biogenesis occurs early during the muscle regeneration.

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We investigated the spatial and temporal expression patterns of hypoxia-inducible factor-1α (HIF-1α) during muscle regeneration and myogenesis in a C2C12 cell culture system. The expression of HIF-1α synchronized with that of myogenic regulatory genes during muscle regeneration at both the mRNA and protein levels. The HIF-1α protein was localized in the nuclei of newly formed regenerating myofibers in three different muscle injury models, including freezing, bupivacaine injection, and muscular dystrophy.

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