共查询到20条相似文献,搜索用时 625 毫秒
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D A Konkel 《Molecular endocrinology (Baltimore, Md.)》1988,2(10):883-885
The ras oncogenes play a crucial role in the regulation of cellular proliferation, probably by coupling growth factor receptors to the PI second messenger pathway. Additional experiments are needed to verify and detail this mechanism, and to examine the question of differing roles for the three ras variants. 相似文献
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R Smith 《BMJ (Clinical research ed.)》1987,295(6608):1248-1252
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We report a series of experiments on social problem solving in chimpanzees, Pan troglodytes. In each experiment a subordinate and a dominant individual were put into competition over two pieces of food. In all experiments dominants obtained virtually all of the foods to which they had good visual and physical access. However, subordinates were successful quite often in three situations in which they had better visual access to the food than the dominant, for example, when the food was positioned so that only the subordinate (and not the dominant) could see it. In some cases, the subordinate might have been monitoring the behaviour of the dominant directly and simply avoided the food that the dominant was moving towards (which just happened to be the one it could see). In other cases, however, we ruled out this possibility by giving subordinates a small headstart and forcing them to make their choice (to go to the food that both competitors could see, or the food that only they could see) before the dominant was released into the area. Together with other recent studies, the present investigation suggests that chimpanzees know what conspecifics can and cannot see, and, furthermore, that they use this knowledge to devise effective social-cognitive strategies in naturally occurring food competition situations. Copyright 2000 The Association for the Study of Animal Behaviour. 相似文献
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Basal ganglia (BG) constitute a network of seven deep brain nuclei involved in a variety of crucial brain functions including:
action selection, action gating, reward based learning, motor preparation, timing, etc. In spite of the immense amount of
data available today, researchers continue to wonder how a single deep brain circuit performs such a bewildering range of
functions. Computational models of BG have focused on individual functions and fail to give an integrative picture of BG function.
A major breakthrough in our understanding of BG function is perhaps the insight that activities of mesencephalic dopaminergic
cells represent some form of ‘reward’ to the organism. This insight enabled application of tools from ‘reinforcement learning,’
a branch of machine learning, in the study of BG function. Nevertheless, in spite of these bright spots, we are far from the
goal of arriving at a comprehensive understanding of these ‘mysterious nuclei.’ A comprehensive knowledge of BG function has
the potential to radically alter treatment and management of a variety of BG-related neurological disorders (Parkinson’s disease,
Huntington’s chorea, etc.) and neuropsychiatric disorders (schizophrenia, obsessive compulsive disorder, etc.) also. In this
article, we review the existing modeling literature on BG and hypothesize an integrative picture of the function of these
nuclei. 相似文献
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T-box genes: what they do and how they do it 总被引:16,自引:0,他引:16
Smith J 《Trends in genetics : TIG》1999,15(4):154-158
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In the December 28, 2001 issue of Cell, Hoang and Ferré-D'Amaré report the structure of a tRNA pseudouridine synthase, showing the target uridine flipped out from the tRNA and confirming that base flipping is not limited to enzymes that act on DNA. 相似文献
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