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SK channel subtypes enable parallel optimized coding of behaviorally relevant stimulus attributes: A review

CHANNELS 2017年第4期11卷 281-304页

作者： Huang, Chengjie G. Chacron, Maurice J. McGill Univ Dept Physiol Montreal PQ Canada

Ion channels play essential roles toward determining how neurons respond to sensory input to mediate perception and behavior. Small conductance calcium-activated potassium (SK) channels are found ubiquitously throughout the brain and have been extensively characterized both molecularly and physiologically in terms of structure and function. It is clear that SK channels are key determinants of neural excitability as they mediate important neuronal response properties such as spike frequency adaptation. However, the functional roles of the different known SK channel subtypes are not well understood. Here we review recent evidence from the electrosensory system of weakly electric fish suggesting that the function of different SK channel subtypes is to optimize the processing of independent but behaviorally relevant stimulus attributes. Indeed, natural sensory stimuli frequently consist of a fast time-varying waveform (i.e., the carrier) whose amplitude (i.e., the envelope) varies slowly and independently. We first review evidence showing how somatic SK2 channels mediate tuning and responses to carrier waveforms. We then review evidence showing how dendritic SK1 channels instead determine tuning and optimize responses to envelope waveforms based on their statistics as found in the organism's natural environment in an independent fashion. The high degree of functional homology between SK channels in electric fish and their mammalian orthologs, as well as the many important parallels between the electrosensory system and the mammalian visual, auditory, and vestibular systems, suggest that these functional roles are conserved across systems and species.

关键词： envelope information theory optimal coding SK channels weakly electric fish

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Image statistics at the point of gaze during human navigation

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VISUAL NEUROSCIENCE 2009年第1期26卷 81-92页

作者： Rothkopf, Constantin A. Ballard, Dana H. Univ Frankfurt Frankfurt Inst Adv Studies D-60438 Frankfurt Germany Univ Rochester Ctr Visual Sci Dept Brain & Cognit Sci Rochester NY 14627 USA Univ Frankfurt Dept Comp Sci D-60438 Frankfurt Germany

Theories of efficient sensory processing have considered the regularities of image properties due to the structure of the environment in order to explain properties of neuronal representations of the visual world. The regularities imposed on the input to the visual system due to the regularities of the active selection process mediated by the voluntary movements of the.:yes have been considered to a much lesser degree. This is surprising, given that the active nature of vision is well established. The present article investigates statistics of image features at the center of gaze of human subjects navigating through a virtual environment and avoiding and approaching different objects. The analysis shows that contrast can be significantly higher or lower at fixation location compared to random locations, depending on whether subjects avoid or approach targets. Similarly, significant differences in the distribution of responses of model simple and complex cells between horizontal and vertical orientations are found over timescales of tens of seconds. B, clustering the model simple cell responses, it is established that gaze was directed toward three distinct features of intermediate complexity the vast majority of time. Thus, this study demonstrates and quantifies how the visuomotor tasks of approaching and avoiding objects during navigation determine feature statistics of the input to the visual system through the combined influence on body and eye movements.

关键词： Active vision Image statistics Gaze selection optimal coding

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The optimal Control and Oplimized Algorithm of a Generalized Nonstationary Stochastic Process

The Optimal Control and Oplimized Algorithm of a Generalized...

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International Conference on Smart Grid and Electrical Automation (ICSGEA)

作者： Xiao Xiaonan Xiamen Univ Tan Kah Kee Coll Zhangzhou 363105 Peoples R China

ISBN: (纸本)9781538669532

Applying the method of optimal non-linear filtering and majorized algorithm, this paper discusses the optimal control of a generalized stochastic process;which yields two optimal control mathematical models and illustrated how to establish the optimal coding and *** provides an effective and reliable approach for the optimal control of such a process.

关键词： generalized process random signal non-linear filtering majorized algorithm optimal control optimal coding

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Lossless encoding based on redistribution of statistics

Lossless encoding based on redistribution of statistics

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International Conference on Information Technology - coding and Computing

作者： Grigoryan, AM Dursun, S Regentova, EE Univ Texas Dept Elect Engn San Antonio TX 78249 USA

ISBN: (纸本)0769521088

A new technique for optimally encoding a given source statistical properties of which are described by the first-order model is introduced. The calculation of codeword lengths is based on construction of a new source with statistics that is determined by the consecutive redistribution of the probabilities of symbols in accordance with their original probabilities at each stage of the encoding. The proposed method performs equally well for different orders of symbol probabilities. While codewords are generated by a, separate combinatorial procedure, the overall computational cost of the proposed method is lower than that for the Huffman code.

关键词： The Huffman code optimal coding

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ROBUST TRANSMISSION OVER CHANNELS WITH CHANNEL UNCERTAINTY: AN ALGORITHMIC PERSPECTIVE

ROBUST TRANSMISSION OVER CHANNELS WITH CHANNEL UNCERTAINTY: ...

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IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Boche, Holger Schaefer, Rafael F. Poor, H. Vincent Tech Univ Munich Inst Theoret Informat Technol Munich Germany Munich Ctr Quantum Sci & Technol Munich Germany Tech Univ Berlin Informat Theory & Applicat Berlin Germany Princeton Univ Dept Elect Engn Princeton NJ 08544 USA

ISBN: (纸本)9781509066315

The availability and quality of channel state information heavily influences the performance of wireless communication systems. For perfect channel knowledge, optimal signal processing and coding schemes are well studied and often closed-form solutions are known. On the other hand, the case of imperfect channel information is much less understood and closed-form solutions remain unknown in general. This paper approaches this question from a fundamental, algorithmic point of view to study whether or not such optimal schemes can be found algorithmically in principle (without putting any constraints on the computational complexity of such algorithms). To this end, the compound channel is considered as a model for channel uncertainty and it is shown that although the compound channel itself is a computable channel, the corresponding capacity is not computable in general, i.e., there exists no algorithm or Turing machine that takes the channel as an input and computes the corresponding capacity. As an implication of this, it is then shown that for such compound channels, there are no effectively constructible optimal signal processing and coding schemes that achieve the capacity. This is particularly noteworthy as such schemes must exist (since the capacity is known), but they cannot be effectively, i.e., algorithmically, constructed.

关键词： Robust communication channel uncertainty optimal coding Turing computability

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A Kind of Partially Measurable Useful Signal's optimal Control

A Kind of Partially Measurable Useful Signal's Optimal Contr...

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International Conference on Intelligent Transportation, Big Data & Smart City (ICITBS)

作者： Xiao Xiaonan Xiamen Univ Tan Kah Kee Coll Zhangzhou Fujian Peoples R China

ISBN: (纸本)9781509060610

The article makes use of nonlinear filter theory and reviews the best control of being quadratic functional linear systems under the condition of incomplete number and continuous time and obtains two best control mathematic models which contain quadratic boss functions under tow cases. It also provides another effective probability statistic method to the best statistic decision.

关键词： nonstationary stochastic process transmission system majorized algorithm optimal control optimal coding optimal decoding

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Compression and the origins of Zipf's law for word frequencies

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COMPLEXITY 2016年第S2期21卷 409-411页

作者： Ferrer-I-Cancho, Ramon Univ Politecn Cataluna Dept Ciencies Comp Complex & Quantitat Linguist Lab LARCA Res Grp Campus Nord Barcelona Catalonia Spain

Here we sketch a new derivation of Zipf's law for word frequencies based on optimal coding. The structure of the derivation is reminiscent of Mandelbrot's random typing model but it has multiple advantages over random typing: (1) it starts from realistic cognitive pressures, (2) it does not require fine tuning of parameters, and (3) it sheds light on the origins of other statistical laws of language and thus can lead to a compact theory of linguistic laws. Our findings suggest that the recurrence of Zipf's law in human languages could originate from pressure for easy and fast communication. (c) 2016 Wiley Periodicals, Inc. Complexity 21: 409-411, 2016

关键词： Zipf's law compression optimal coding random typing

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How a well-adapted immune system is organized

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PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2015年第19期112卷 5950-5955页

作者： Mayer, Andreas Balasubramanian, Vijay Mora, Thierry Walczak, Aleksandra M. Univ Paris 06 Phys Theor Lab F-75005 Paris France Univ Paris 06 CNRS Lab Phys Stat F-75005 Paris France Ecole Normale Super F-75005 Paris France Univ Penn Dept Phys & Astron Philadelphia PA 19104 USA CUNY Grad Ctr Initiat Theoret Sci New York NY 10016 USA

The repertoire of lymphocyte receptors in the adaptive immune system protects organisms from diverse pathogens. A well-adapted repertoire should be tuned to the pathogenic environment to reduce the cost of infections. We develop a general framework for predicting the optimal repertoire that minimizes the cost of infections contracted from a given distribution of pathogens. The theory predicts that the immune system will have more receptors for rare antigens than expected from the frequency of encounters;individuals exposed to the same infections will have sparse repertoires that are largely different, but nevertheless exploit cross-reactivity to provide the same coverage of antigens;and the optimal repertoires can be reached via the dynamics of competitive binding of antigens by receptors and selective amplification of stimulated receptors. Our results follow from a tension between the statistics of pathogen detection, which favor a broader receptor distribution, and the effects of cross-reactivity, which tend to concentrate the optimal repertoire onto a few highly abundant clones. Our predictions can be tested in high-throughput surveys of receptor and pathogen diversity.

关键词： immune repertoires optimal coding repertoire diversity competitive exclusion jamming

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Neural substrates of perception in the vestibular thalamus during natural self-motion: A review

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Current Research in Neurobiology 2023年 4卷 100073页

作者： Cullen, Kathleen E. Chacron, Maurice J. Department of Biomedical Engineering Johns Hopkins University Baltimore United States Department of Otolaryngology-Head and Neck Surgery Johns Hopkins University School of Medicine Baltimore United States Department of Neuroscience Johns Hopkins University School of Medicine Baltimore United States Kavli Neuroscience Discovery Institute Johns Hopkins University Baltimore United States Department of Physiology McGill University Montréal Canada

Accumulating evidence across multiple sensory modalities suggests that the thalamus does not simply relay information from the periphery to the cortex. Here we review recent findings showing that vestibular neurons within the ventral posteriolateral area of the thalamus perform nonlinear transformations on their afferent input that determine our subjective awareness of motion. Specifically, these neurons provide a substrate for previous psychophysical observations that perceptual discrimination thresholds are much better than predictions from Weber's law. This is because neural discrimination thresholds, which are determined from both variability and sensitivity, initially increase but then saturate with increasing stimulus amplitude, thereby matching the previously observed dependency of perceptual self-motion discrimination thresholds. Moreover, neural response dynamics give rise to unambiguous and optimized encoding of natural but not artificial stimuli. Finally, vestibular thalamic neurons selectively encode passively applied motion when occurring concurrently with voluntary (i.e., active) movements. Taken together, these results show that the vestibular thalamus plays an essential role towards generating motion perception as well as shaping our vestibular sense of agency that is not simply inherited from afferent input. © 2023 The Authors

关键词： Adaptation Neural coding optimal coding Perception Vestibular Voluntary movement

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