Influence Of Noise Variability And Time Delayed Feedback On Spatially Extended Systems

Influence of Noise, Variability, and Time-delayed Feedback on Spatially Extended Systems

Variability in Human Performance

Understanding the conditions under which variability in performance may arise, and the processes related to its emergence, gives us insight into the development of techniques for improving the quality of performance. Variability in Human Performance details the scientific and the practical implications of human performance variability by providing a broad perspective on how and why such variability occurs across a number of disciplinary domains. The text takes an approach that rests upon the idea of context, or design, specificity in performance, namely that variability in performance is closely referenced to design factors in the environment in which performance is occurring. An exploration of the link between variability and related processes, the book introduces a comprehensive framework for understanding human performance variability, presented in terms of how human control of behavior is closely tied to design factors in the performance environment. The authors introduce empirical evidence, as well as practical examples and application areas, in support of this framework. The book begins with coverage of neurobiological and biomechanical basis of movement variability, then examines rich and extensive empirical evidence available for context specificity in cognitive performance and learning, as a basis for cognitive performance variability. The book then reviews the evidence for context specificity in: Student learning Displaced feedback conditions Human error behavior Affective performance Social and team performance The authors also explore work performance as influenced by complex sociotechnical systems and as a basis for performance variability, applying control systems concepts to an interpretation of the nature and basis of performance variability in all of these domains. They conclude by taking an evolutionary perspective on the origins and behavioral significance of human performance variability. The book then provides strategies on how individuals, groups, and organizations can significantly reduce variability in human performance that often leads to systems failures.

Neuronal Stochastic Variability: Influences on Spiking Dynamics and Network Activity

Stochastic fluctuations are intrinsic to and unavoidable at every stage of neural dynamics. For example, ion channels undergo random conformational changes, neurotransmitter release at synapses is discrete and probabilistic, and neural networks are embedded in spontaneous background activity. The mathematical and computational tool sets contributing to our understanding of stochastic neural dynamics have expanded rapidly in recent years. New theories have emerged detailing the dynamics and computational power of the balanced state in recurrent networks. At the cellular level, novel stochastic extensions to the classical Hodgkin-Huxley model have enlarged our understanding of neuronal dynamics and action potential initiation. Analytical methods have been developed that allow for the calculation of the firing statistics of simplified phenomenological integrate-and-fire models, taking into account adaptation currents or temporal correlations of the noise. This Research Topic is focused on identified physiological/internal noise sources and mechanisms. By "internal", we mean variability that is generated by intrinsic biophysical processes. This includes noise at a range of scales, from ion channels to synapses to neurons to networks. The contributions in this Research Topic introduce innovative mathematical analysis and/or computational methods that relate to empirical measures of neural activity and illuminate the functional role of intrinsic noise in the brain.