| 1. |
- Fukushima, Takuya, et al.
(författare)
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Optimal value estimation of intentional-value-substitution for learning regression models
- 2021
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Ingår i: Journal of Advanced Computational Intelligence and Intelligent Informatics. - : Fuji Technology Press. - 1343-0130 .- 1883-8014. ; 25:2, s. 153-161
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on a method to train a regression model from incomplete input values. It is assumed in this paper that there are no missing values in a training dataset while missing values exist during a prediction phase using the trained model. Under this assumption, we propose Intentional-Value-Substitution (IVS) training to obtain amachine learningmodel that makes the prediction error as minimum as possible. In IVS training, a model is trained to approximate the target function using a modified training dataset in which some feature values are substituted with a certain value even though their values are not missing. It is shown through a series of computational experiments that the substitution values calculated from a mathematical analysis help the models correctly predict outputs for inputs with missing values.
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| 2. |
- Kinoshita, Masaharu, et al.
(författare)
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Genetic dissection of the circuit for hand dexterity in primates
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 487:7406, s. 235-U1510
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Tidskriftsartikel (refereegranskat)abstract
- It is generally accepted that the direct connection from the motor cortex to spinal motor neurons is responsible for dexterous hand movements in primates(1-3). However, the role of the 'phylogenetically older' indirect pathways from the motor cortex to motor neurons, mediated by spinal interneurons, remains elusive. Here we used a novel double-infection technique to interrupt the transmission through the propriospinal neurons (PNs)(4-6), which act as a relay of the indirect pathway in macaque monkeys (Macaca fuscata and Macaca mulatta). The PNs were double infected by injection of a highly efficient retrograde gene-transfer vector into their target area and subsequent injection of adeno-associated viral vector at the location of cell somata. This method enabled reversible expression of green fluorescent protein (GFP)-tagged tetanus neurotoxin, thereby permitting the selective and temporal blockade of the motor cortex-PN-motor neuron pathway. This treatment impaired reach and grasp movements, revealing a critical role for the PN-mediated pathway in the control of hand dexterity. Anti-GFP immunohistochemistry visualized the cell bodies and axonal trajectories of the blocked PNs, which confirmed their anatomical connection to motor neurons. This pathway-selective and reversible technique for blocking neural transmission does not depend on cell-specific promoters or transgenic techniques, and is a new and powerful tool for functional dissection in system-level neuroscience studies.
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| 3. |
- Kuriyama, Takeo, et al.
(författare)
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Iridophore- and Xanthophore-Deficient Melanistic Color Variant of the Lizard Plestiodon latiscutatus
- 2016
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Ingår i: Herpetologica. - 0018-0831. ; 72:3, s. 189-195
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Tidskriftsartikel (refereegranskat)abstract
- Elucidating the ultimate and proximate mechanisms of melanistic color pattern formation has become an important focus of evolutionary biology. There are relatively few studies, however, examining the composition and architecture of pigment cells in melanistic reptiles. The typical color pattern of the skink Plestiodon latiscutatus, which inhabits the Izu Islands and Izu Peninsula of Japan, consists of brown dorsal coloration, five vivid yellowish white stripes, and a blue tail (in juveniles). We have observed melanistic morphs at a low frequency (<0.05%). Based on a histological examination of pigment cells, we determined that the melanistic morph of P. latiscutatus collected from Shikine in the Izu Islands possesses only dermal melanophores and lacks the xanthophores and iridophores seen in the normal coloration. This arrangement of pigment cells differs from the only other studied melanistic lizard, Sceloporus undulatus, in which the dark skin of the melanistic morph results from a simple increase in the density of melanophores relative to xanthophores and iridophores. Our findings indicate that associations between color pattern phenotypes and the expression of candidate color genes, such as Mc1r, are more complex than previously assumed; coloration in reptiles is controlled not only by cellular processes related to single pigment production but also by the differentiation of multiple pigment cells.
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