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11.
Eirini Mavritsaki Dietmar Heinke Glyn W Humphreys Gustavo Deco 《Journal of Physiology》2006,100(1-3):110-124
In the real world, visual information is selected over time as well as space, when we prioritise new stimuli for attention. Watson and Humphreys [Watson, D., Humphreys, G.W., 1997. Visual marking: prioritizing selection for new objects by top-down attentional inhibition of old objects. Psychological Review 104, 90-122] presented evidence that new information in search tasks is prioritised by (amongst other processes) active ignoring of old items - a process they termed visual marking. In this paper we present, for the first time, an explicit computational model of visual marking using biologically plausible activation functions. The "spiking search over time and space" model (sSoTS) incorporates different synaptic components (NMDA, AMPA, GABA) and a frequency adaptation mechanism based on [Ca(2+)] sensitive K(+) current. This frequency adaptation current can act as a mechanism that suppresses the previously attended items. We show that, when coupled with a process of active inhibition applied to old items, frequency adaptation leads to old items being de-prioritised (and new items prioritised) across time in search. Furthermore, the time course of these processes mimics the time course of the preview effect in human search. The results indicate that the sSoTS model can provide a biologically plausible account of human search over time as well as space. 相似文献
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Apostolidou E Kambas K Chrysanthopoulou A Kourtzelis I Speletas M Ritis K Mitroulis I 《Molecular biology reports》2012,39(5):5503-5510
Familial Mediterranean fever (FMF) is an autoinflammatory disease, characterized by MEFV gene mutations and self-limited recurrent episodes of fever and localized serositis. Complement system is a key regulator
of the inflammatory process. The aim of this study was to investigate the genetic alterations and mRNA expression pattern
of C5aR and C5L2 genes in neutrophils from attack-free FMF patients. No mutations were observed in the two receptors’ genes, while the genetic
alteration observed in the C5aR1 gene was identified as N279 K polymorphic variant. Furthermore, lower mRNA expression of C5L2 gene was observed in neutrophils from FMF patients compared to control subjects. The binding capacity of rhC5a and the ability
to produce reactive oxygen species was similar in neutrophils from healthy subjects and FMF patients and independent of the
presence of N279 K polymorphism or mRNA expression of C5L2. 相似文献
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Kostas Kampourakis Eirini Palaiokrassa Maria Papadopoulou Vasiliki Pavlidi Myrto Argyropoulou 《Evolution》2012,5(2):279-291
Research has shown that children usually provide teleological explanations for the features of organisms and artifacts, from
a very early age (3–4 years old). However, there is no consensus on whether teleological explanations are given in the same
manner for non-living natural objects as well. The present study aimed to document the teleological explanations of 5- to
8-year-old children for particular features (color and shape) of organisms, artifacts and non-living natural objects. In addition,
it was examined if there was any correlation between these explanations and children’s explanations for the usefulness of
those features. Our results indicate a developmental shift in children’s teleological explanations, from a non-selective teleology
in pre-school to a selective one in the second grade. In the latter case, children provided teleological explanations mostly
for the shape of the feet of organisms and for the shape of artifacts, whereas pre-school children provided teleological explanations
for non-living natural objects as well, both for the color and for the shape in all cases. Our results are not conclusive
and further research is required, including a larger spectrum of students, since teleology is one of the most important conceptual
obstacles in understanding evolution that persists even into adulthood. We conclude by proposing a particular research program
for this purpose. 相似文献
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Hammachi F Morrison GM Sharov AA Livigni A Narayan S Papapetrou EP O'Malley J Kaji K Ko MS Ptashne M Brickman JM 《Cell reports》2012,1(2):99-109
Oct4 is an essential regulator of pluripotency in vivo and in vitro in embryonic stem cells, as well as a key mediator of the reprogramming of somatic cells into induced pluripotent stem cells. It is not known whether activation and/or repression of specific genes by Oct4 is relevant to these functions. Here, we show that fusion proteins containing the coding sequence of Oct4 or Xlpou91 (the Xenopus homolog of Oct4) fused to activating regions, but not those fused to repressing regions, behave as Oct4, suppressing differentiation and promoting maintenance of undifferentiated phenotypes in vivo and in vitro. An Oct4 activation domain fusion supported embryonic stem cell self-renewal in vitro at lower concentrations than that required for Oct4 while alleviating the ordinary requirement for the cytokine LIF. At still lower levels of the fusion, LIF dependence was restored. We conclude that the necessary and sufficient function of Oct4 in promoting pluripotency is to activate specific target genes. 相似文献
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Adenosine A2A receptors are required for glutamate mGluR5‐ and dopamine D1 receptor‐evoked ERK1/2 phosphorylation in rat hippocampus: involvement of NMDA receptor
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Paraskevi Krania Eleni Dimou Maria Bantouna Stylianos Kouvaros Eirini Tsiamaki Costas Papatheodoropoulos Konstantinos Sarantis Fevronia Angelatou 《Journal of neurochemistry》2018,145(3):217-231
19.
Banas SM Rouch C Kassis N Markaki EM Gerozissis K 《Cellular and molecular neurobiology》2009,29(2):157-168
Early changes in neuroendocrine pathways are essential in the development of metabolic pathologies. Thus, it is important
to have a better understanding of the signals involved in their initiation. Long-term consumption of high-fat diets induces
insulin resistance, obesity, diabetes. Here, we have investigated early neural and endocrine events in the hypothalamus and
hippocampus induced by a short-term high fat, low carbohydrate diet in adult male Wistar rats. The release of serotonin, which
is closely associated with the actions of insulin and leptin, was measured, by electrochemical detection following reverse-phase
liquid chromatography (HPLC), in the extracellular space of the medial hypothalamus and the dorsal hippocampus in samples
obtained from non-anesthetized animals, by microdialysis. The high-fat diet had a specific effect on the hypothalamus. Serotonin
release induced by food intake was reduced after 1 week, and effectively ceased after 6 weeks of the diet. After 1 week, there
was an increased gene expression of the insulin receptor and the insulin receptor substrates IRS1 and IRS2, as measured by
real-time PCR. After 6 weeks of diet, insulin gene expression increased. Leptinemia increased in all cases. This new data
support the concept that high-fat diets, in addition to have peripheral effects, cause a rapid alteration in specific central
mechanisms involved in energy and glucose homeostasis. The changes in the gene expression of insulin and signaling elements
represent possible adaptations aimed at counterbalancing the reduced responsiveness of the serotonergic system to nutritional
signals and maintaining homeostasis.
Sophie M. Banas and Claude Rouch have contributed equally to this work. 相似文献
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Panagiotis E. Simitzis Maria A. Charismiadou Basiliki Kotsampasi George Papadomichelakis Eugenia P. Christopoulou Eirini K. Papavlasopoulou Stelios G. Deligeorgis 《Applied animal behaviour science》2009,116(2-4):191-197
The objective of the present experiment was to determine the implications of prenatal undernutrition on the behaviour of juvenile lambs. Dams of one group (C) were fed 100% of the recommended requirements throughout pregnancy, while those of two other groups were fed 50% of the control nutrient allowance during the first 30 days of pregnancy (R1) or 50% of the control nutrient allowance from days 31–100 of pregnancy (R2). Between 2 and 5 months old, behaviour of lambs was tested by the implementation of 2 types of test: isolation and novelty. There were no statistical differences between lamb treatments in escape behaviour and heart rates during isolation test, or the latency to approach a novel or a familiar object in the novelty test in tests conducted at 2, 3, 4 and 5 months of age.Male lambs showed a tendency of turning to the right-hand side of the test pen, irrespective of treatment group, between the age of 2 and 5 months old. A greater proportion of C compared to R1 males turned right at the age of 2 and 5 months old (P < 0.05). Significant differences concerning laterality were found also between C and R1 female lambs at the age of 2 and 4 months old (P < 0.001), between C and R2 male lambs at the age of 2 months old (P < 0.05), between C and R2 female lambs at the age of 4 and 5 months old (P < 0.01), between R1 and R2 male lambs at the age of 2 and 5 months old (P < 0.05) and between R1 and R2 female lambs at the age of 2 months old (P < 0.001).It is concluded that prenatal undernutrition during different periods of pregnancy had no effect on fear-related behaviour, but effect on laterality at the early stages of lamb age between 2 and 5 months old. 相似文献