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Search Results: 1 - 10 of 1687 matches for " Koji Jimura "
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Primary and Secondary Rewards Differentially Modulate Neural Activity Dynamics during Working Memory
Stefanie M. Beck,Hannah S. Locke,Adam C. Savine,Koji Jimura,Todd S. Braver
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009251
Abstract: Cognitive control and working memory processes have been found to be influenced by changes in motivational state. Nevertheless, the impact of different motivational variables on behavior and brain activity remains unclear.
Dynamically Allocated Hub in Task-Evoked Network Predicts the Vulnerable Prefrontal Locus for Contextual Memory Retrieval in Macaques
Takahiro Osada?,Yusuke Adachi?,Kentaro Miyamoto?,Koji Jimura,Rieko Setsuie?,Yasushi Miyashita
PLOS Biology , 2015, DOI: 10.1371/journal.pbio.1002177
Abstract: Neuroimaging and neurophysiology have revealed that multiple areas in the prefrontal cortex (PFC) are activated in a specific memory task, but severity of impairment after PFC lesions is largely different depending on which activated area is damaged. The critical relationship between lesion sites and impairments has not yet been given a clear mechanistic explanation. Although recent works proposed that a whole-brain network contains hubs that play integrative roles in cortical information processing, this framework relying on an anatomy-based structural network cannot account for the vulnerable locus for a specific task, lesioning of which would bring impairment. Here, we hypothesized that (i) activated PFC areas dynamically form an ordered network centered at a task-specific “functional hub” and (ii) the lesion-effective site corresponds to the “functional hub,” but not to a task-invariant “structural hub.” To test these hypotheses, we conducted functional magnetic resonance imaging experiments in macaques performing a temporal contextual memory task. We found that the activated areas formed a hierarchical hub-centric network based on task-evoked directed connectivity, differently from the anatomical network reflecting axonal projection patterns. Using a novel simulated-lesion method based on support vector machine, we estimated severity of impairment after lesioning of each area, which accorded well with a known dissociation in contextual memory impairment in macaques (impairment after lesioning in area 9/46d, but not in area 8Ad). The predicted severity of impairment was proportional to the network “hubness” of the virtually lesioned area in the task-evoked directed connectivity network, rather than in the anatomical network known from tracer studies. Our results suggest that PFC areas dynamically and cooperatively shape a functional hub-centric network to reallocate the lesion-effective site depending on the cognitive processes, apart from static anatomical hubs. These findings will be a foundation for precise prediction of behavioral impacts of damage or surgical intervention in human brains.
Destination Brands: Managing Place Reputation (Book Review)
Takamitsu Jimura
Enlightening Tourism : a Pathmaking Journal , 2011,
Abstract:
Local Signal Time-Series during Rest Used for Areal Boundary Mapping in Individual Human Brains
Satoshi Hirose, Takamitsu Watanabe, Koji Jimura, Masaki Katsura, Akira Kunimatsu, Osamu Abe, Kuni Ohtomo, Yasushi Miyashita, Seiki Konishi
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036496
Abstract: It is widely thought that resting state functional connectivity likely reflects functional interaction among brain areas and that different functional areas interact with different sets of brain areas. A method for mapping areal boundaries has been formulated based on the large-scale spatial characteristics of regional interaction revealed by resting state functional connectivity. In the present study, we present a novel analysis for areal boundary mapping that requires only the signal timecourses within a region of interest, without reference to the information from outside the region. The areal boundaries were generated by the novel analysis and were compared with those generated by the previously-established standard analysis. The boundaries were robust and reproducible across the two analyses, in two regions of interest tested. These results suggest that the information for areal boundaries is readily available inside the region of interest.
Dissociable Temporo-Parietal Memory Networks Revealed by Functional Connectivity during Episodic Retrieval
Satoshi Hirose, Hiroko M. Kimura, Koji Jimura, Akira Kunimatsu, Osamu Abe, Kuni Ohtomo, Yasushi Miyashita, Seiki Konishi
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071210
Abstract: Episodic memory retrieval most often recruits multiple separate processes that are thought to involve different temporal regions. Previous studies suggest dissociable regions in the left lateral parietal cortex that are associated with the retrieval processes. Moreover, studies using resting-state functional connectivity (RSFC) have provided evidence for the temporo-parietal memory networks that may support the retrieval processes. In this functional MRI study, we tested functional significance of the memory networks by examining functional connectivity of brain activity during episodic retrieval in the temporal and parietal regions of the memory networks. Recency judgments, judgments of the temporal order of past events, can be achieved by at least two retrieval processes, relational and item-based. Neuroimaging results revealed several temporal and parietal activations associated with relational/item-based recency judgments. Significant RSFC was observed between one parahippocampal region and one left lateral parietal region associated with relational recency judgments, and between four lateral temporal regions and another left lateral parietal region associated with item-based recency judgments. Functional connectivity during task was found to be significant between the parahippocampal region and the parietal region in the RSFC network associated with relational recency judgments. However, out of the four tempo-parietal RSFC networks associated with item-based recency judgments, only one of them (between the left posterior lateral temporal region and the left lateral parietal region) showed significant functional connectivity during task. These results highlight the contrasting roles of the parahippocampal and the lateral temporal regions in recency judgments, and suggest that only a part of the tempo-parietal RSFC networks are recruited to support particular retrieval processes.
Comparison of Discharge Duration Curves from Two Adjacent Forested Catchments—Effect of Forest Age and Dominant Tree Species  [PDF]
Koji Tamai
Journal of Water Resource and Protection (JWARP) , 2010, DOI: 10.4236/jwarp.2010.28086
Abstract: The effects of forest age and dominant tree species on the water discharge volume have been analyzed by a paired-watershed experiment in two adjacent catchments in Tatsunokuchi-yama Experimental Forest, western Japan. The control period is 1937-1943. The treated periods are 1948-1953, 1968-1977, and 1996-2003. In these treated periods, the forest age or the dominant tree species were different between two adjacent periods. Differences in the discharge duration curves from the two catchments are compared for the control and the treated periods. A significant change in the discharge duration curves is seen in the third treated period (1996-2003) on days with low water, when the forest age difference between the adjacent catchments was 35 years. This is believed to be the result of differences in forest age and forest treatment just after the occurrence of pine wilt disease.
Diagnosis of occult fractures of the ischiopubic rami  [PDF]
Koji Suzuki
Journal of Biomedical Science and Engineering (JBiSE) , 2013, DOI: 10.4236/jbise.2013.63A049
Abstract:
Introduction: Recently, the diagnosis of occult frac- tures has been facilitated due to increased availability and utilization of MRI. Diagnosing a fracture of the ischiopubic rami from a proximal femoral fracture, in particular, is difficult using physical exam alone and can be facilitated by having access to an MRI. Here we report both physical exam findings and MRI findings that help in differentiating occult fractures of the iliopubic rami. Materials and Methods: From April 2010 to December 2012, we identified 30 pa- tients (5 male and 25 female; aged 43 - 93 years old). We recorded if a traumatic episode occurred, ambu- latory status at the initial visit (bed ridden, standing up with an aid, walking with an aid). We also re- corded if imaging was used in determining the final diagnosis (radiographs, MRI or CT). Results: Twenty- one patients had a fracture as a result of a traumatic episode. In the remaining 9 cases, no trauma oc- curred and therefore the fractures were insufficiency fractures. Ten patients were bed ridden at the initial visit, eight patients were able to stand only with a walking aid, and the remaining twelve patients were able to walk with an aid. Occasional radiographs were used to confirm the presence of a fracture in 4 cases, MRI in 11 cases, and CT scan in 15 cases. Dis- cussion and Conclusions: Occult fractures of the is- chiopubic rami can occur without trauma and it can be difficult to differentiate these fractures from occult proximal femoral fractures. In these cases, MRI is useful to definitively obtain a diagnosis. In cases of pacemaker, bullet implantation or artificial hip joints, CT or occasional radiographs are also useful to diag- nose occult fractures of the ischiopubic rami.
Reply to “Comments on ‘There Is No Axiomatic System for the Quantum Theory’”  [PDF]
Koji Nagata
Journal of Quantum Information Science (JQIS) , 2014, DOI: 10.4236/jqis.2014.44018
Abstract: Barros discusses that [Jose Acacio de Barros, Int. J. Theor. Phys. 50, 1828 (2011)] Nagata derives inconsistencies from quantum mechanics [K. Nagata, Int. J. Theor. Phys. 48, 3532 (2009)]. Barros considers that the inconsistencies do not come from quantum mechanics, but from extra assumptions about the reality of observables. Here we discuss the fact that there is a contradiction within the quantum theory. We discuss the fact that only one expected value in a spin-1/2 pure state 〈σxrules out the reality of the observable. We do not accept extra assumptions about the reality of observables. We use the actually measured results of quantum measurements (raw data). We use a single Pauli observable. We stress that we can use the quantum theory even if we give up the axiomatic system for the quantum theory.
An Additional Consideration of Reliability and Validity of the Differentiation of Self Scale in Two Domains  [PDF]
Koji Kudo
Psychology (PSYCH) , 2018, DOI: 10.4236/psych.2018.910138
Abstract: This study addressed the insufficient verification of reliability and validity of the Differentiation of Self Scale in Two Domains (DSS-2D). Although the DSS-2D is the first measure in Japan that satisfies the three requirements (corresponding to two domains, applicable to a wide range of adolescents, and a moderate number of items), verification of reliability and validity of the DSS-2D has remained insufficient. Two questionnaire surveys were conducted with university students (n = 70 at T1, n = 68 at T2). The interval of the surveys was one month. The results indicate that the DSS-2D had sufficient test-retest reliability and concurrent validity in each domain of differentiation of self. These results provide support for the DSS-2D as a valid and adequate measure for use in Japan.
Von Neumann’s Theory, Projective Measurement, and Quantum Computation  [PDF]
Koji Nagata, Tadao Nakamura
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.37108
Abstract: We discuss the fact that there is a crucial contradiction within Von Neumann’s theory. We derive a proposition concerning a quantum expected value under an assumption of the existence of the orientation of reference frames in N spin-1/2 systems (1 ≤ N < +∞). This assumption intuitively depictures our physical world. However, the quantum predictions within the formalism of Von Neumann’s projective measurement violate the proposition with a magnitude that grows exponentially with the number of particles. We have to give up either the existence of the directions or the formalism of Von Neumann’s projective measurement. Therefore, Von Neumann’s theory cannot depicture our physical world with a violation factor that grows exponentially with the number of particles. The theoretical formalism of the implementation of the Deutsch-Jozsa algorithm relies on Von Neumann’s theory. We investigate whether Von Neumann’s theory meets the Deutsch-Jozsa algorithm. We discuss the fact that the crucial contradiction makes the quantum-theoretical formulation of Deutsch-Jozsa algorithm questionable. Further, we discuss the fact that projective measurement theory does not meet an easy detector model for a single Pauli observable. Especially, we systematically describe our assertion based on more mathematical analysis using raw data. We propose a solution of the problem. Our solution is equivalent to changing Planck’s constant \"\" to a new constant \"\". It may be said that a new type of the quantum theory early approaches Newton’s theory in the macroscopic scale than the old quantum theory does. We discuss how our solution is used in an implementation of Deutsch’s algorithm.
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