control dynamics

  • 文章类型: Journal Article
    人类灵活行为的关键要素涉及持续预测和准备任务或动作的突然变化的能力。这里,我们测试了当待执行任务的身份变得不确定时,人们是否可以动态调整任务准备过程和决策策略。为此,我们开发了一个新的范例,参与者需要为每项试验的9项任务中的一项做准备.至关重要的是,在一些街区,正在准备的任务可能会在更长的提示-目标间隔后突然转移到另一个任务,通过更改定义初始任务的刺激类别或分类规则。我们发现,面对这种任务不确定性,参与者能够动态调整任务准备。第二个实验表明,这些行为的变化不仅仅是任务期望值降低的函数,而是增加转换预期。最后,在第三和第四个实验中,我们证明了这些动态调制可以以组合的方式应用,这取决于是否只有刺激类别或分类规则会发生变化。
    A key element of human flexible behavior concerns the ability to continuously predict and prepare for sudden changes in tasks or actions. Here, we tested whether people can dynamically modulate task preparation processes and decision-making strategies when the identity of a to-be-performed task becomes uncertain. To this end, we developed a new paradigm where participants need to prepare for one of nine tasks on each trial. Crucially, in some blocks, the task being prepared could suddenly shift to a different task after a longer cue-target interval, by changing either the stimulus category or categorization rule that defined the initial task. We found that participants were able to dynamically modulate task preparation in the face of this task uncertainty. A second experiment shows that these changes in behavior were not simply a function of decreasing task expectancy, but rather of increasing switch expectancy. Finally, in the third and fourth experiment, we demonstrate that these dynamic modulations can be applied in a compositional manner, depending on whether either only the stimulus category or categorization rule would be expected to change.
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  • 文章类型: Journal Article
    路径积分是一种感觉运动计算,可用于通过积分自运动线索来推断潜在的动态状态。我们使用新颖的运动提示算法研究了感官观察(视觉/前庭)和潜在控制动力学(速度/加速度)对人体路径集成的影响。感觉形态和控制动力学在试验中都是随机变化的,当参与者控制操纵杆引导到虚拟现实中记忆的目标位置时。只有当参与者控制他们的加速度时,视觉和前庭转向提示才允许相当的准确性,表明前庭信号,靠自己,在没有持续加速的情况下,无法支持准确的路径整合。然而,在所有条件下的性能反映了未能完全适应基础控制动态的变化,这一结果很好地解释了动力学估计中的偏差。这项工作证明了尽管有连续的感官反馈,但不正确的控制动力学内部模型如何影响易变环境中的导航。
    Path integration is a sensorimotor computation that can be used to infer latent dynamical states by integrating self-motion cues. We studied the influence of sensory observation (visual/vestibular) and latent control dynamics (velocity/acceleration) on human path integration using a novel motion-cueing algorithm. Sensory modality and control dynamics were both varied randomly across trials, as participants controlled a joystick to steer to a memorized target location in virtual reality. Visual and vestibular steering cues allowed comparable accuracies only when participants controlled their acceleration, suggesting that vestibular signals, on their own, fail to support accurate path integration in the absence of sustained acceleration. Nevertheless, performance in all conditions reflected a failure to fully adapt to changes in the underlying control dynamics, a result that was well explained by a bias in the dynamics estimation. This work demonstrates how an incorrect internal model of control dynamics affects navigation in volatile environments in spite of continuous sensory feedback.
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  • 文章类型: Journal Article
    In nature, gene regulatory networks are a key mediator between the information stored in the DNA of living organisms (their genotype) and the structural and behavioral expression this finds in their bodies, surviving in the world (their phenotype). They integrate environmental signals, steer development, buffer stochasticity, and allow evolution to proceed. In engineering, modeling and implementations of artificial gene regulatory networks have been an expanding field of research and development over the past few decades. This review discusses the concept of gene regulation, describes the current state of the art in gene regulatory networks, including modeling and simulation, and reviews their use in artificial evolutionary settings. We provide evidence for the benefits of this concept in natural and the engineering domains.
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  • 文章类型: Journal Article
    In uncertain environments, decision-makers must balance two goals: they must \"exploit\" rewarding options but also \"explore\" in order to discover rewarding alternatives. Exploring and exploiting necessarily change how the brain responds to identical stimuli, but little is known about how these states, and transitions between them, change how the brain transforms sensory information into action. To address this question, we recorded neural activity in a prefrontal sensorimotor area while monkeys naturally switched between exploring and exploiting rewarding options. We found that exploration profoundly reduced spatially selective, choice-predictive activity in single neurons and delayed choice-predictive population dynamics. At the same time, reward learning was increased in brain and behavior. These results indicate that exploration is related to sudden disruptions in prefrontal sensorimotor control and rapid, reward-dependent reorganization of control dynamics. This may facilitate discovery through trial and error.
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  • 文章类型: Journal Article
    Cognitive control (with the closely related concepts of attention control and executive function) encompasses the collection of processes that are involved in generating and maintaining appropriate task goals and suppressing task goals that are no longer relevant, as well as the way in which current goal representations are used to modify attentional biases to improve task performance. Here, we provide a comprehensive but nonexhaustive review of this complex literature, with an emphasis on the contributions made by techniques for studying human brain function. The review is divided into five sections: (a) overview and historical perspective of cognitive control, its subcomponent processes, and its neural substrate; (b) most common types of tasks used to assess and/or manipulate the level of control; (c) main research findings obtained with various imaging methodologies, with a focus on ERP data, and briefer overviews of oscillatory (event-related spectral perturbations) and fMRI data; (d) major theories of cognitive control; and (e) discussion of open questions regarding how to integrate the various dimensions of control, as well as the faster versus slower temporal dynamics informing this complex and multifaceted concept.
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  • 文章类型: Journal Article
    Mathematical models of parasite transmission provide powerful tools for assessing the impacts of interventions. Owing to complexity and uncertainty, no single model may capture all features of transmission and elimination dynamics. Multi-model ensemble modelling offers a framework to help overcome biases of single models. We report on the development of a first multi-model ensemble of three lymphatic filariasis (LF) models (EPIFIL, LYMFASIM, and TRANSFIL), and evaluate its predictive performance in comparison with that of the constituents using calibration and validation data from three case study sites, one each from the three major LF endemic regions: Africa, Southeast Asia and Papua New Guinea (PNG). We assessed the performance of the respective models for predicting the outcomes of annual MDA strategies for various baseline scenarios thought to exemplify the current endemic conditions in the three regions. The results show that the constructed multi-model ensemble outperformed the single models when evaluated across all sites. Single models that best fitted calibration data tended to do less well in simulating the out-of-sample, or validation, intervention data. Scenario modelling results demonstrate that the multi-model ensemble is able to compensate for variance between single models in order to produce more plausible predictions of intervention impacts. Our results highlight the value of an ensemble approach to modelling parasite control dynamics. However, its optimal use will require further methodological improvements as well as consideration of the organizational mechanisms required to ensure that modelling results and data are shared effectively between all stakeholders.
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  • 文章类型: Journal Article
    在三维世界中导航时,与环境中的对象保持适当间隙的能力很重要。先前的研究表明,引导/接近物体对向的视角及其变化率是定时拦截的重要变量,防撞,制动的连续调节,和手动控制的头。然而,航向维护的调查要求参与者保持固定的航向距离,并且没有调查如何考虑有关自身速度的信息。在下面的实验中,我们要求参与者使用操纵杆跟踪计算机模拟的铅物体.结果表明,跟随速度,并且铅物体的大小对平均跟随距离和跟随距离方差都有显着影响。此外,当假设引导对象的期望视觉范围会随时间变化时,参与者的操纵杆响应模型提供了更好的拟合。一起来看,结果表明,当控制器使用有关自身速度的信息来设置所需的航向目标时,间距的连续调节主要受引导物体的视角及其变化率的影响。对视角的依赖,它的变化率,和/或自身速度信息也根据系统的控制动态而变化。这些发现与最优控制标准一致,该标准反映了根据工厂动态对不同信息源的不同加权。与其他对运动的深度判断一样,用于控制与环境中其他对象的进度的信息取决于任务的约束和不同的控制策略。
    The ability to maintain appropriate gaps to objects in one\'s environment is important when navigating through a three-dimensional world. Previous research has shown that the visual angle subtended by a lead/approaching object and its rate of change are important variables for timing interceptions, collision avoidance, continuous regulation of braking, and manual control of headway. However, investigations of headway maintenance have required participants to maintain a fixed distance headway and have not investigated how information about own-speed is taken into account. In the following experiment, we asked participants to use a joystick to follow computer-simulated lead objects. The results showed that ground texture, following speed, and the size of the lead object had significant effects on both mean following distances and following distance variance. Furthermore, models of the participants\' joystick responses provided better fits when it was assumed that the desired visual extent of the lead object would vary over time. Taken together, the results indicate that while information about own-speed is used by controllers to set the desired headway to a lead object, the continuous regulation of headway is influenced primarily by the visual angle of the lead object and its rate of change. The reliance on visual angle, its rate of change, and/or own-speed information also varied depending on the control dynamics of the system. Such findings are consistent with an optimal control criterion that reflects a differential weighting on different sources of information depending on the plant dynamics. As in other judgements of motion in depth, the information used for controlling headway to other objects in the environment varies depending on the constraints of the task and different strategies of control.
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