934 resultados para corticostriatal connections
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The human auditory cortex comprises the supratemporal plane and large parts of the temporal and parietal convexities. We have investigated the relevant intrahemispheric cortico-cortical connections using in vivo DSI tractography combined with landmark-based registration, automatic cortical parcellation and whole-brain structural connection matrices in 20 right-handed male subjects. On the supratemporal plane, the pattern of connectivity was related to the architectonically defined early-stage auditory areas. It revealed a three-tier architecture characterized by a cascade of connections from the primary auditory cortex to six adjacent non-primary areas and from there to the superior temporal gyrus. Graph theory-driven analysis confirmed the cascade-like connectivity pattern and demonstrated a strong degree of segregation and hierarchy within early-stage auditory areas. Putative higher-order areas on the temporal and parietal convexities had more widely spread local connectivity and long-range connections with the prefrontal cortex; analysis of optimal community structure revealed five distinct modules in each hemisphere. The pattern of temporo-parieto-frontal connectivity was partially asymmetrical. In conclusion, the human early-stage auditory cortical connectivity, as revealed by in vivo DSI tractography, has strong similarities with that of non-human primates. The modular architecture and hemispheric asymmetry in higher-order regions is compatible with segregated processing streams and lateralization of cognitive functions.
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Comparative ultrastructural study of the intercellular connections between parasite and host cells in two algal parasitic systems, Gelidiocolax christianae Feldmann and Feldmann/Ge/iV/ium spathulatum (Kutz.) Bornet and Gelidiocolax deformans Seoane Camba/Gelidium sesquipedale (Clem.) Thur, shows quantitative and structural differences. The number of free conjunctor cells (before fusión with the adjacent host cells) differs between the two parasitic systems and is inversely related to the number of complex pit connections. The fibrillar cell wall structure of the conjunctor cells and the lamellar structure of the complex pit plugs in the two systems are also different A hypothesis concerning the different activity of the conjuntor cell wall in the two parasitic systems, related with the different structural appearance, is proposed.
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Identification of neuroimaging biomarkers following extreme prematurity (EP) and intrauterine growth restriction (IUGR) is crucial for understanding their cognitive and behavioral impairments at school age
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The emergence of social media has led many companies to adopt them as marketing channels. Yet these media are novel enough that many marketers are still unsure as to how to plan an effective social media marketing strategy, actually oriented towards engaging prospects. In this article, we discuss how to shape a social media strategy. To do so, we show the key concepts and steps involved in the planning process of this type of digital marketing strategy, and how to measure their impact immediately.
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Webben är en enorm källa för information. Innehållet på webbsidorna är en synlig typ av information, men webben innehåller även information av en annan typ, en mera gömd typ i form av sambanden och nätverken som hyperlänkarna skapar mellan webbsajterna och –sidorna som de kopplar ihop. Forskningsområdet webometri ämnar, bland annat, att skapa ny kunskap ur denna gömda information som finns inbyggt i hyperlänkarna samt att skapa förståelse för hurudana fenomen och förhållanden utanför webben kan finnas representerade i hyperlänkarna. Målet med denna forskning var att öka förståelse för användningen av hyperlänkar på webben och speciellt kommunernas användning av hyperlänkar. Denna forskning undersökte hur kommunerna i Egentliga Finland skapade och mottog hyperlänkar samt hurudana nätverk formades av dessa hyperlänkar. Forskningen kartlade nätverk av direkta länkar mellan kommunerna och av samlänkar till och från kommunerna och undersökte ifall dessa nätverk kunde användas för att undersöka geopolitiska förhållanden och samarbete mellan kommunerna i Egentliga Finland. De övergripande forskningsfrågorna som har besvarats i denna forskning är: 1) Från ett webometriskt perspektiv, hur använder kommunerna i Egentliga Finland webben? 2) Kan hyperlänkar (direkta länkar och samlänkar) användas för att kartlägga geopolitiska förhållanden och samarbete mellan kommuner? 3) Vilka är de viktigaste motiveringarna för att skapa länkar mellan, till och från kommunernas webbsajter? Denna forskning kom till ovanligt tydliga resultat för en webometrisk forskning, både när det gäller upptäckta geografiska faktorer som påverkar hyperlänkningarna och de klassificerade motivationerna för att skapa länkarna. Resultaten visade att de direkta hyperlänkarna mellan kommunerna kan användas för att kartlägga geopolitiska förhållanden och samarbete mellan kommunerna för att de direkta länkarna var motiverade av officiella orsaker och de var klart påverkade av distansen mellan kommunerna och av de ekonomiska regionerna. Samlänkningarna in till kommunerna visade sig fungera som ett mått för geografisk likhet mellan kommunerna, medan samlänkningarna ut från kommunerna visade potential för att kunna användas till för att kartlägga kommunernas gemensamma intressen. Forskningen kontribuerade även till utvecklandet av forskningsområdet webometri. En del av de viktigaste kontributionerna av denna forskning var utvecklandet av nya metoder för webometrisk forskning samt att öka kunskap om hur existerande metoder från nätverksanalys kan användas effektivt för webometrisk forskning. Resultaten från denna forskning och de utvecklade metoderna kan användas för snabba kartläggningar av diverse förhållanden mellan olika organisationer och företag genom att använda information gratis tillgängligt på webben.
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Trusses are structural systems commonly used in projects, being employed mainly in roof structures, present in most rural buildings. The design of trusses, as well as other structural systems, requires the determination of displacements, strains and stresses. However, the project is developed from an ideal model of calculation, considering free rotation between the elements of a connection. This paper presents a computer program for the analysis of bidimensional wooden trusses with connections formed with two screws per node. The formulation is based on the flexibility method, taking into account the influence of the effect of semi-rigid connections formed by two screws. An example of a structure is presented and analyzed by the program developed here, highlighting the importance of behavior analysis on semi-rigid connections.
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Esitys Kirjastoverkkopäivillä 22.10.2014 Helsingissä – Presentation of Jakob Voß at the Library Network Days, October 22, 2014 in Helsinki.
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Metastasis is a multistep cascade initiated when malignant cells penetrate the tissue surrounding the primary tumor and enter the bloodstream. Classic studies indicated that blood platelets form complexes around tumor cells in the circulation and facilitate metastases. In other work, the anticoagulant drug heparin diminished metastasis in murine models, as well is in preliminary human studies. However, attempts to follow up the latter observation using vitamin K antagonists failed, indicating that the primary mechanism of heparin action was unrelated to its anticoagulant properties. Other studies showed that the overexpression of sialylated fucosylated glycans in human carcinomas is associated with a poor prognosis. We have now brought all these observations together into one mechanistic explanation, which has therapeutic implications. Carcinoma cells expressing sialylated fucosylated mucins can interact with platelets, leukocytes and endothelium via the selectin family of cell adhesion molecules. The initial organ colonization of intravenously injected carcinoma cells is attenuated in P-selectin-deficient mice, in mice receiving tumor cells pretreated with O-sialoglycoprotease (to selectively remove mucins from cell surfaces), or in mice receiving a single dose of heparin prior to tumor cell injection. In each case, we found that formation of a platelet coating on cancer cells was impeded, allowing increased access of leukocytes to the tumor cells. Several weeks later, all animals showed a decrease in the extent of established metastasis, indicating a long-lasting effect of the short-term intervention. The absence of obvious synergism amongst the three treatments suggests that they all act via a common pathway. Thus, a major mechanism of heparin action in cancer may be inhibition of P-selectin-mediated platelet coating of tumor cells during the initial phase of the metastatic process. We therefore suggest that heparin use in cancer be re-explored, specifically during the time interval between initial visualization of a primary tumor until just after definitive surgical removal.
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In the last five years, a number of detailed anatomical, electrophysiological, optical imaging and simulation studies performed in a variety of non-human species have revealed that the functional organization of callosal connections between primary visual areas is more elaborate than previously thought. Callosal cell bodies and terminals are clustered in columns whose correspondence to features mapped in the visual cortex, such as orientation and ocularity, are starting to be understood. Callosal connections are not restricted to the vertical midline representation nor do they establish merely point-to-point retinotopic correspondences across the hemispheres, as traditionally believed. In addition, anatomical studies have revealed the existence of an ipsilateral component of callosal axons. The aim of this short review is to propose how these new data can be integrated into an updated scheme of the circuits responsible for assembling the primary visual field map.
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The periaqueductal gray (PAG) has been traditionally considered to be an exit relay for defensive responses. Functional mapping of its subdivisions has advanced our knowledge of this structure, but synthesis remains difficult mainly because results from lesion and stimulation studies have not correlated perfectly. After using a strategy that combined both techniques and a reevaluation of the available literature on PAG function and connections, we propose here that freezing could be mediated by different PAG subdivisions depending on the presence of immediate danger or exposure to related signaling cues. These subdivisions are separate functional entities with distinct descending and ascending connections that are likely to play a role in different defensive responses. The existence of ascending connections also suggests that the PAG is not simply a final common path for defensive responses. For example, the possibility that indirect ascending connections to the cingulate cortex could play a role in the expression of freezing evoked by activation of the neural substrate of fear in the dorsal PAG has been considered.
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This essay proposes that the ecologic association shown between the 20th century coronary heart disease epidemic and the 1918 influenza pandemic could shed light on the mechanism associated with the high lethality of the latter. It suggests that an autoimmune interference at the apoB-LDL interface could explain both hypercholesterolemia and inflammation (through interference with the cellular metabolism of arachidonic acid). Autoimmune inflammation, then, would explain the 1950s-60s acute coronary events (coronary thrombosis upon influenza re-infection) and the respiratory failure seen among young adults in 1918. This hypothesis also argues that the lethality of the 1918 pandemic may have not depended so much on the 1918 virus as on an immune vulnerability to it, possibly resulting from an earlier priming of cohorts born around 1890 by the 1890 influenza pandemic virus.
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The 5th International Conference of Young Folklorists 7-9.10.2015, Viljandi, Estland.
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At head of title: "The tourist route of America".