degeneracy

简并性
  • 文章类型: Journal Article
    足球运动员在得分目标(完成情况)附近的决策行为来自游戏环境中直接感知到的不断变化的时空信息。在完成的情况下,球手关于投篮或传球的决策不是个人决策过程,而是由玩家对比赛负担能力的看法指导的集体决定。为了维持这个想法,我们收集了时空信息,并建立了一个模型来量化“完成空间值”(FSV),该模型来自玩家对两个主要问题的感知能力:(a)对手的目标是否可以从给定的音高位置成功到达?;(b)从每个给定的音高位置,反对派背景将允许足够的空间来射击(低对手干扰)?FSV是用高性能足球比赛的位置数据计算的,将从Voronoi图(VD)中提取的信息与球门线的距离和角度相结合。FSV使用“专家小组”(PE)的意见作为参考进行测试,由足球教练组成,关于一份问卷,介绍50种完成情况。结果显示,PE用来评估球架射门的可能性与针对相同情况计算的FSV之间存在很强的关联(R2=0.6706)。此外,我们证明了FSV量化模型在预测教练对完成比赛的“最佳选择”的意见时的准确性。总的来说,结果表明,FSV是一个有前途的模型,可以为高性能足球中的球手决策捕捉射击环境的能力。FSV可能有助于进行更精确的比赛分析,并在设计代表性练习任务时告知教练。
    Football players\' decision-making behaviours near the scoring target (finishing situations) emerge from the evolving spatiotemporal information directly perceived in the game\'s landscape. In finishing situations, the ball carrier\'s decision-making about shooting or passing is not an individual decision-making process, but a collective decision that is guided by players\' perceptions of match affordances. To sustain this idea, we collected spatiotemporal information and built a model to quantify the \"Finishing Space Value\" (FSV) that results from players\' perceived affordances about two main questions: (a) is the opponent\'s target successfully reachable from a given pitch location?; and (b) from each given pitch location, the opposition context will allow enough space to shoot (low adversaries\' interference)? The FSV was calculated with positional data from high-performance football matches, combining information extracted from Voronoi diagrams (VD) with distances and angles to the goal line. FSV was tested using as a reference the opinion of a \"panel of expert\" (PE), composed by football coaches, about a questionnaire presenting 50 finishing situations. Results showed a strong association between the subjective perception scale used by the PE to assess how probable a shot made by the ball carrier could result in a goal and FSV calculated for that same situation (R2=0.6706). Moreover, we demonstrate the accuracy of the FSV quantification model in predicting coaches\' opinions about what should be the \"best option\" to finish the play. Overall, results indicated that the FSV is a promising model to capture the affordances of the shooting circumstances for the ball carrier\'s decision-making in high-performance football. FSV might be useful for more precise match analysis and informing coaches in the design of representative practice tasks.
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  • 文章类型: Journal Article
    复杂系统既不是完全确定的,也不是完全随机的。生物复杂系统,包括单个神经元,表现出随机性的中间机制,这些机制招募了功能隔离的子系统的特定组合的整合。这种生物学功能的出现为简并性的表达提供了底物,子系统的不同组合产生相似功能的能力。这里,我们提供了通过不同离子通道组合的功能整合在齿状回颗粒细胞(GC)的形态学现实模型中简并性表达的证据。我们进行了45个参数的随机搜索,跨越16个主动和被动离子通道,每个人都受到其门控动力学和定位曲线的生物物理限制,搜索有效的GC模型。有效的模型是那些满足来自大鼠GC的17个亚阈值和超阈值细胞尺度电生理测量的模型。15,000个随机模型中的绝大多数(>99%)不是电生理有效的,证明了任意随机的离子通道组合不会产生GC函数。141个有效模型(15,000个模型中的0.94%)在局部和传播的电生理测量中表现出异质性和交叉依赖性,与他们各自的生物对应物相匹配。重要的是,这些有效的模型在整个参数空间中都很普遍,并且在不同参数之间表现出微弱的交叉依赖性。这些观察结果共同表明,GC生理学既不能通过完全随机的离子通道组合获得,也没有完全确定的满足所有约束的单一参数组合。复杂性,测量空间和参数空间中的异质性,与GC生理学相关的简并性应严格考虑,同时评估GC及其在生理和病理条件下的稳健性。
    Complex systems are neither fully determined nor completely random. Biological complex systems, including single neurons, manifest intermediate regimes of randomness that recruit integration of specific combinations of functionally segregated subsystems. Such emergence of biological function provides the substrate for the expression of degeneracy, the ability of disparate combinations of subsystems to yield similar function. Here, we present evidence for the expression of degeneracy in morphologically realistic models of dentate gyrus granule cells (GC) through functional integration of disparate ion-channel combinations. We performed a 45-parameter randomized search spanning 16 active and passive ion channels, each biophysically constrained by their gating kinetics and localization profiles, to search for valid GC models. Valid models were those that satisfied 17 sub- and supra-threshold cellular-scale electrophysiological measurements from rat GCs. A vast majority (>99%) of the 15,000 random models were not electrophysiologically valid, demonstrating that arbitrarily random ion-channel combinations wouldn\'t yield GC functions. The 141 valid models (0.94% of 15,000) manifested heterogeneities in and cross-dependencies across local and propagating electrophysiological measurements, which matched with their respective biological counterparts. Importantly, these valid models were widespread throughout the parametric space and manifested weak cross-dependencies across different parameters. These observations together showed that GC physiology could neither be obtained by entirely random ion-channel combinations nor is there an entirely determined single parametric combination that satisfied all constraints. The complexity, the heterogeneities in measurement and parametric spaces, and degeneracy associated with GC physiology should be rigorously accounted for, while assessing GCs and their robustness under physiological and pathological conditions.
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  • 文章类型: Journal Article
    保持平衡是一个复杂的运动问题,需要多个生物系统的协调作用。衰老不可避免地降低了生物系统的保真度,这可能会导致跌倒的风险增加,和相关的伤害。安全着陆是有利的,但是坠落以不同的方式表现出来,因此需要不同的电机解决方案才能安全着陆。然而,没有相当多的实践,很难召回适合跌倒的电机解决方案,然后在撞击地面之前的短暂时间内有效地应用它。复杂的系统透视图提供了一个镜头,通过该镜头可以查看安全着陆的问题。可以使用运动类比来促进感知运动系统内的退化,以便,不管老年人跌倒的方向,他们的身体自我组织着陆,受伤的可能性较小。
    Maintaining balance is a complex motor problem that requires coordinated contributions from multiple biological systems. Aging inevitably lessens the fidelity of biological systems, which can result in an increased risk of falling, and associated injuries. It is advantageous to land safely, but falls manifest in diverse ways, so different motor solutions are required to land safely. However, without considerable practice, it is difficult to recall the appropriate motor solution for a fall and then apply it effectively in the brief duration before hitting the ground. A complex systems perspective provides a lens through which to view the problem of safe-landing. It may be possible to use motor analogies to promote degeneracy within the perceptual-motor system so that, regardless of the direction in which an older person falls, their body self-organizes to land with less likelihood of injury.
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  • 文章类型: Journal Article
    简并性和对称性在量子系统中有着深远的关系。这里,我们报道了具有几乎对称横截面形状的PbTe纳米线中的门可调谐子带简并性。由于没有量子化平台,在电子传输中揭示了简并性。利用双门设计,我们可以施加电场来提升简并性,反映为高原的出现。在先前的纳米线实验中观察到这种简并性及其可调提升是具有挑战性的,可能是由于混乱。数值模拟可以定性地捕获我们的观察结果,为未来的应用提供器件参数的光照。
    Degeneracy and symmetry have a profound relation in quantum systems. Here, we report gate-tunable subband degeneracy in PbTe nanowires with a nearly symmetric cross-sectional shape. The degeneracy is revealed in electron transport by the absence of a quantized plateau. Utilizing a dual gate design, we can apply an electric field to lift the degeneracy, reflected as emergence of the plateau. This degeneracy and its tunable lifting were challenging to observe in previous nanowire experiments, possibly due to disorder. Numerical simulations can qualitatively capture our observation, shedding light on device parameters for future applications.
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  • 文章类型: Journal Article
    来自网络科学和图论的概念,包括网络主题的框架,已被广泛用于研究神经元网络和其他生物复杂系统。基于网络的方法也可以用于研究单个神经元的功能,其中细胞元素,如离子通道和膜电压被概念化为网络中的节点,它们的相互作用由边表示。在这种情况下,网络基序提供了有助于阐明细胞神经生理学原理的功能构建块。在这篇综述中,我们建立了一个案例,即在神经元内运行的网络基序为定义单神经元生理学和神经元适应的功能架构提供了工具。我们强调了这种计算基序在潜在的动作电位产生的细胞机制中的存在,神经元振荡,树突状整合,和神经元可塑性。应用网络主题观点的未来工作可能有助于破译神经元的功能复杂性及其在健康和疾病期间的适应性。
    Concepts from network science and graph theory, including the framework of network motifs, have been frequently applied in studying neuronal networks and other biological complex systems. Network-based approaches can also be used to study the functions of individual neurons, where cellular elements such as ion channels and membrane voltage are conceptualized as nodes within a network, and their interactions are denoted by edges. Network motifs in this context provide functional building blocks that help to illuminate the principles of cellular neurophysiology. In this review we build a case that network motifs operating within neurons provide tools for defining the functional architecture of single-neuron physiology and neuronal adaptations. We highlight the presence of such computational motifs in the cellular mechanisms underlying action potential generation, neuronal oscillations, dendritic integration, and neuronal plasticity. Future work applying the network motifs perspective may help to decipher the functional complexities of neurons and their adaptation during health and disease.
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  • 文章类型: Journal Article
    伤害性感觉神经元使用动作电位将疼痛相关信号传递到CNS。电压门控钠通道NaV1.7中的功能丧失突变会导致对疼痛不敏感(可能是通过降低伤害感受器的兴奋性),但试图通过抑制NaV1.7药理学来治疗疼痛的临床试验一直在努力。这可能反映了NaV1.7对伤害感受器兴奋性的可变贡献。与NaV1.7是伤害感受器启动动作电位所必需的说法相反,我们表明,使用NaV1.3,NaV1.7和NaV1.8的不同组合,伤害感受器可以获得相似的兴奋性。只有当其他亚型弱表达时,选择性阻断其中一种NaV亚型才能降低伤害感受器的兴奋性。例如,在急性分离的伤害感受器中,兴奋性依赖于NaV1.8,但在培养的第四天,责任转移到NaV1.7和NaV1.3。炎症后体内NaV依赖性发生类似的变化,影响NaV1.7选择性抑制剂PF-05089771在行为测试中减轻疼痛的能力。灵活使用不同的NaV亚型可以证明简并性-使用不同的成分实现类似的功能-并损害亚型选择性抑制剂对伤害感受器兴奋性的可靠调节。确定主要的NaV亚型以预测药物功效并不是微不足道的。在分子水平选择药物靶标时,必须考虑细胞水平的简并性。
    Nociceptive sensory neurons convey pain-related signals to the CNS using action potentials. Loss-of-function mutations in the voltage-gated sodium channel NaV1.7 cause insensitivity to pain (presumably by reducing nociceptor excitability) but clinical trials seeking to treat pain by inhibiting NaV1.7 pharmacologically have struggled. This may reflect the variable contribution of NaV1.7 to nociceptor excitability. Contrary to claims that NaV1.7 is necessary for nociceptors to initiate action potentials, we show that nociceptors can achieve similar excitability using different combinations of NaV1.3, NaV1.7, and NaV1.8. Selectively blocking one of those NaV subtypes reduces nociceptor excitability only if the other subtypes are weakly expressed. For example, excitability relies on NaV1.8 in acutely dissociated nociceptors but responsibility shifts to NaV1.7 and NaV1.3 by the fourth day in culture. A similar shift in NaV dependence occurs in vivo after inflammation, impacting ability of the NaV1.7-selective inhibitor PF-05089771 to reduce pain in behavioral tests. Flexible use of different NaV subtypes exemplifies degeneracy - achieving similar function using different components - and compromises reliable modulation of nociceptor excitability by subtype-selective inhibitors. Identifying the dominant NaV subtype to predict drug efficacy is not trivial. Degeneracy at the cellular level must be considered when choosing drug targets at the molecular level.
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  • 文章类型: Journal Article
    同义突变是由遗传密码的简并性引起的。大多数氨基酸由两个或多个密码子编码,将一个密码子改变为另一个同义密码子的突变不会改变基因产物中的氨基酸。历史上,这种突变被认为是沉默的,因为它们被认为没有影响。然而,过去几十年的研究已经产生了几个例子,其中同义突变发挥了重要作用。这些包括通过增强翻译起始和通过密码子使用和mRNA二级结构加速或减速翻译延伸来优化表达。稳定mRNA分子并防止其在翻译前分解,和错误的蛋白质折叠或由于泛素化增强和蛋白质次优分泌到适当的细胞区室而导致的降解增加。同义突变的一些后果,如mRNA稳定性,在原核生物和真核生物中可能导致不同的结果。尽管有这些例子,同义突变与改变蛋白质氨基酸残基的非同义突变相比,在进化和致病中的意义仍存在争议.同义突变所描述的影响生物体的分子机制是否可以被概括仍然知之甚少,值得在这一领域进行未来的研究。
    Synonymous mutations result from the degeneracy of the genetic code. Most amino acids are encoded by two or more codons, and mutations that change a codon to another synonymous codon do not change the amino acid in the gene product. Historically, such mutations have been considered silent because they were assumed to have no to very little impact. However, research in the last few decades has produced several examples where synonymous mutations play important roles. These include optimizing expression by enhancing translation initiation and accelerating or decelerating translation elongation via codon usage and mRNA secondary structures, stabilizing mRNA molecules and preventing their breakdown before translation, and faulty protein folding or increased degradation due to enhanced ubiquitination and suboptimal secretion of proteins into the appropriate cell compartments. Some consequences of synonymous mutations, such as mRNA stability, can lead to different outcomes in prokaryotes and eukaryotes. Despite these examples, the significance of synonymous mutations in evolution and in causing disease in comparison to nonsynonymous mutations that do change amino acid residues in proteins remains controversial. Whether the molecular mechanisms described by which synonymous mutations affect organisms can be generalized remains poorly understood and warrants future research in this area.
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  • 文章类型: Journal Article
    漫长的19世纪是农业和动物生物学许多发展和技术创新的时期,在此期间,行为者试图根据新信息纳入新的做法。到本世纪中叶,然而,虽然遗传稳步成为畜牧业的主导概念,一些与巴西牲畜改良相关的政策似乎是根据法国博物学家乔治·路易斯·勒克莱尔在18世纪中叶建立的气候确定性概念而制定的,布冯伯爵.他的动物退化理论提出,除其他外,反复杂交以保护生活在非本地环境中的动物物种免受气候引起的退化的必要性。尽管在19世纪初基本上名誉扫地,法国博物学家的教导似乎在巴西通过应用自然科学实现国家农业现代化的计划中找到了支持者。在这里,我研究了布冯理论在政府资助的改善畜牧业和育种技术的计划中的复兴,包括该理论在现实世界中的实际应用。最终,我认为,布冯的退化理论被用来调整公共政策和资金,以改善1856年至1860年间巴西的驯养动物。
    The long 19th century was a period of many developments and technical innovations in agriculture and animal biology, during which actors sought to incorporate new practices in light of new information. By the middle of the century, however, while heredity steadily became the dominant concept in animal husbandry, some policies related to livestock improvement in Brazil seemed to have been tailored following a climate-deterministic concept established in the mid-18th century by the French naturalist Georges-Louis Leclerc, the Comte de Buffon. His theory of animal degeneration posited, among other things, the necessity of recurrent crossbreeding to preserve animal species living in nonnative environments from climate-induced degeneration. Although largely discredited by the early 19th century, the teachings of the French naturalist seem to have found supporters in a Brazilian program to modernize national agriculture through the application of the natural sciences. Herein I examine the revival of Buffon\'s theories in that government-sponsored program to improve animal husbandry and breeding techniques, including actual applications of this theory in the real world. Ultimately, I argue that Buffon\'s theory of degeneration was used to tailor public policies and funding for the improvement of domesticated animals in Brazil between 1856 and 1860.
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  • 文章类型: Journal Article
    在细胞水平,急性温度变化改变离子电导,离子通道动力学,和整个神经元回路的活动。这可能会对神经功能造成严重后果,动物行为和生存。在变热动物中,特别是在核心温度等于周围水温的水生物种中,神经元经历相当快速和广泛的温度波动。甲壳动物口胃神经系统中模式生成神经回路的最新工作表明,神经元回路可以对温度波动表现出内在的鲁棒性。然而,考虑到气候变化导致的海洋变暖和反复出现的热浪,问题是这种内在的鲁棒性是否可以适应不断变化的环境条件,以及物种和海洋栖息地之间的差异。
    我们使用两种螃蟹的胃胃神经系统中的幽门模式生成回路来解决这些问题,近几十年来,半血脑和Carcinusmaenas在全球范围内扩张。
    与它们作为入侵物种的历史一致,我们发现幽门活动表现出广泛的温度稳健性(>30°C)。此外,温度稳健范围取决于两个物种的栖息地温度。适应温暖的动物将回路活动破坏的临界温度转移到更高的温度。这是以H.sanguineus对冷刺激的鲁棒性为代价的,但不是在C.maenas.比较C.maenas从冷纬度(北海)到温暖纬度(西班牙)的温度响应,表明在自然环境中发生了类似的鲁棒性变化。因此,我们的结果表明,神经元温度鲁棒性与,并回应,环境温度条件,可能为动物准备改变的生态条件和不断变化的栖息地。
    UNASSIGNED: At the cellular level, acute temperature changes alter ionic conductances, ion channel kinetics, and the activity of entire neuronal circuits. This can result in severe consequences for neural function, animal behavior and survival. In poikilothermic animals, and particularly in aquatic species whose core temperature equals the surrounding water temperature, neurons experience rather rapid and wide-ranging temperature fluctuations. Recent work on pattern generating neural circuits in the crustacean stomatogastric nervous system have demonstrated that neuronal circuits can exhibit an intrinsic robustness to temperature fluctuations. However, considering the increased warming of the oceans and recurring heatwaves due to climate change, the question arises whether this intrinsic robustness can acclimate to changing environmental conditions, and whether it differs between species and ocean habitats.
    UNASSIGNED: We address these questions using the pyloric pattern generating circuits in the stomatogastric nervous system of two crab species, Hemigrapsus sanguineus and Carcinus maenas that have seen a worldwide expansion in recent decades.
    UNASSIGNED: Consistent with their history as invasive species, we find that pyloric activity showed a broad temperature robustness (>30°C). Moreover, the temperature-robust range was dependent on habitat temperature in both species. Warm-acclimating animals shifted the critical temperature at which circuit activity breaks down to higher temperatures. This came at the cost of robustness against cold stimuli in H. sanguineus, but not in C. maenas. Comparing the temperature responses of C. maenas from a cold latitude (the North Sea) to those from a warm latitude (Spain) demonstrated that similar shifts in robustness occurred in natural environments. Our results thus demonstrate that neuronal temperature robustness correlates with, and responds to, environmental temperature conditions, potentially preparing animals for changing ecological conditions and shifting habitats.
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  • 文章类型: Journal Article
    实施钙的细胞自主自我调节的神经元如何对单个离子通道电导的敲除作出反应?为了解决这个问题,我们使用了78个基于电导的海马锥体神经元模型的异质群体,这些模型在接受theta频率输入的同时维持了细胞自主钙稳态。在钙稳态下,我们分别从每个模型中删除了11个活性离子通道电导。我们通过比较通道缺失之前和之后的固有电生理特性来测量删除每个电导(一次一个)的急性影响。删除个体电导对生理特性(包括钙稳态)的急性影响是异质的,根据属性,具体的模型,和删除的频道。离子通道和属性之间的潜在多对多映射指向离子通道简并性。接下来,我们允许其他电导(除非删除的电导)在theta频率活动期间朝着实现钙稳态的方向发展。当离子通道缺失扰乱钙稳态时,其他电导的敲除后可塑性确保了钙稳态对离子通道缺失的抵抗力。这些结果证明了钙稳态的简并性,因为基因敲除模型中的钙稳态是在没有较早参与稳态过程的通道的情况下实现的。重要的是,在重新获得稳态时,离子通道电导和生理特性经历了异质可塑性(取决于模型,财产,和删除的频道),甚至在未直接连接到已删除通道的属性中引入更改。一起,基因敲除后可塑性旨在维持体内平衡,在几个通道和特性上引入了异质脱靶效应,这表明在解释涉及通道敲除的实验结果时应格外谨慎。
    How do neurons that implement cell-autonomous self-regulation of calcium react to knockout of individual ion-channel conductances? To address this question, we used a heterogeneous population of 78 conductance-based models of hippocampal pyramidal neurons that maintained cell-autonomous calcium homeostasis while receiving theta-frequency inputs. At calcium steady-state, we individually deleted each of the 11 active ion-channel conductances from each model. We measured the acute impact of deleting each conductance (one at a time) by comparing intrinsic electrophysiological properties before and immediately after channel deletion. The acute impact of deleting individual conductances on physiological properties (including calcium homeostasis) was heterogeneous, depending on the property, the specific model, and the deleted channel. The underlying many-to-many mapping between ion channels and properties pointed to ion-channel degeneracy. Next, we allowed the other conductances (barring the deleted conductance) to evolve towards achieving calcium homeostasis during theta-frequency activity. When calcium homeostasis was perturbed by ion-channel deletion, post-knockout plasticity in other conductances ensured resilience of calcium homeostasis to ion-channel deletion. These results demonstrate degeneracy in calcium homeostasis, as calcium homeostasis in knockout models was implemented in the absence of a channel that was earlier involved in the homeostatic process. Importantly, in reacquiring homeostasis, ion-channel conductances and physiological properties underwent heterogenous plasticity (dependent on the model, the property, and the deleted channel), even introducing changes in properties that were not directly connected to the deleted channel. Together, post-knockout plasticity geared towards maintaining homeostasis introduced heterogenous off-target effects on several channels and properties, suggesting that extreme caution be exercised in interpreting experimental outcomes involving channel knockouts.
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