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作者： Seyedeh Fatemeh Khatami Firoozabadi University of Connecticut

学位级别：博士

The mammalian brain is able to recognize natural sounds in the presence of acoustic uncertainties such as background noise. A prevailing theory of neural coding suggest that neural systems are optimized for natural environment signals and sensory inputs that are biologically relevant. The optimal coding hypothesis thus suggests that neural populations should encode sensory information so as to maximize efficient utilization of environmental inputs. In the first part of my thesis, I will explore the origins of scale invariance phenomena which has been previously described for natural sounds and has been observed in a variety of natural sensory signals including natural scenes. In the second part, I will explore the ability of the brain to utilize high-level statistical regularities in natural sounds to perform sound identification tasks. Using a catalog of natural sounds, texture synthesis procedures to manipulate sounds statistics from various sound categories, and neural recordings from the auditory midbrain of awake rabbits, I will show that neural population response statistics can be used to identify discrete sound categories. In the last part of the thesis, I will explore the role of hierarchical organization in the auditory pathway for sound recognition and optimal coding in the presence of challenging background noise. Using neural responses from auditory nerve, midbrain, and auditory cortex, I developed optimal computational neural network model for word recognition in presence of speech babble noise. I demonstrate that the optimal computational strategy for word recognition in noise predicts various transformations performed by the ascending auditory pathway, including a sequential loss of temporal and spectral resolution, increasing sparseness and selectivity.

关键词： neural coding Sounds Recognition Spectral Features neural recording Auditory system Modeling

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neural coding in the sense of touch: Human sensations of skin indentation compared with the responses of slowly adapting mechanoreceptive afferents innervating the hairy skin of monkeys

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Experimental Brain Research 1970年第3期10卷 251-264页

作者： Harrington, Thomas Merzenich, Michael M. Department of Physiology The Johns Hopkins University School of Medicine Baltimore Maryland United States Laboratory of Neurophysiology 283 Medical Sciences Building University of Wisconsin Madison 53706 Wisconsin United States Department of Psychology University of Nevada Reno Nevada United States

The human capacity to scale the intensity of brief mechanical indentations of the hairy skin was measured by the method of subjective magnitude estimation. The afferent discharges evoked by nearly identical stimuli delivered to comparable locations on the hairy skin in monkeys were recorded in a number of types of first-order mechanoreceptive afferents. It was shown that of these only those which adapt slowly to mechanical stimuli possess sufficient dynamic range of response to account for the range of human pressure sensation. Two such afferents innervating the hairy skin, previously identified by others as the Type I and Type II afferents, were studied in detail as regards their responses to brief mechanical stimuli of different intensities. The relation of the human subject's estimate of intensity to stimulus magnitude is described by a power function with an exponent of about 0.4. Using impulse frequency in the "early steady state" as a measure, the responses of both types of slowly adapting mechanoreceptive afferents are related to stimulus magnitudes by power functions with exponents averaging about 0.5. On the assumption that the stimuli used elicit similar patterns of discharge in the first-order afferents innervating the hairy skin of men and monkeys, the results support the general proposition, now shown to hold for a number of senses, that the intensity of human sensation is determined by the functional properties of the first-order sensory fibers, and that the final behavioral output in the form of a subjective estimate of magnitude is a linear function of the frequency of discharge in those first-order fibers. © 1970 Springer-Verlag.

关键词： Cutaneous Sensibility neural coding Neurophysiology Pressure Psychophysics Touch

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neural population structures and consequences for neural coding

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JOURNAL OF COMPUTATIONAL NEUROSCIENCE 2004年第1期16卷 69-80页

作者： Johnson, DH Rice Univ Dept Elect & Comp Engn Houston TX 77251 USA

Researchers studying neural coding have speculated that populations of neurons would more effectively represent the stimulus if the neurons "cooperated:" by interacting through lateral connections, the neurons would process and represent information better than if they functioned independently. We apply our new theory of information processing to determine the fidelity limits of simple population structures to encode stimulus features. We focus on noncooperative populations, which have no lateral connections. We show that they always exhibit positively correlated responses and that as population size increases, they perfectly represent the information conveyed by their inputs regardless of the individual neuron's coding scheme. Cooperative populations, which do have lateral connections, can, depending on the nature of the connections, perform better or worse than their noncooperative counterparts. We further show that common notions of synergy fail to capture the level of cooperation and to reflect the information processing properties of populations.

关键词： neural coding information theory neural populations

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Theta phase precession and phase selectivity: a cognitive device description of neural coding

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JOURNAL OF neural ENGINEERING 2009年第3期6卷 036002 (18-036002 (18页

作者： Zalay, Osbert C. Bardakjian, Berj L. Univ Toronto Inst Biomat & Biomed Engn Toronto ON M5S 3G9 Canada

Information in neural systems is carried by way of phase and rate codes. Neuronal signals are processed through transformative biophysical mechanisms at the cellular and network levels. neural coding transformations can be represented mathematically in a device called the cognitive rhythm generator (CRG). Incoming signals to the CRG are parsed through a bank of neuronal modes that orchestrate proportional, integrative and derivative transformations associated with neural coding. Mode outputs are then mixed through static nonlinearities to encode (spatio) temporal phase relationships. The static nonlinear outputs feed and modulate a ring device (limit cycle) encoding Output dynamics. Small coupled CRG networks were created to investigate coding functionality associated with neuronal phase preference and theta precession in the hippocampus. Phase selectivity was found to be dependent on mode shape and polarity, while phase precession was a product of modal mixing (i.e. changes in the relative contribution or amplitude of mode outputs resulted in shifting phase preference). Nonlinear system identification was implemented to help validate the model and explain response characteristics associated with modal mixing;in particular, principal dynamic modes experimentally derived from a hippocampal neuron were inserted into a CRG and the neuron's dynamic response was successfully cloned. From our results, small CRG networks possessing disynaptic feedforward inhibition in combination with feedforward excitation exhibited frequency-dependent inhibitory-to-excitatory and excitatory-to-inhibitory transitions that were similar to transitions seen in a single CRG with quadratic modal mixing. This suggests nonlinear modal mixing to be a coding manifestation of the effect of network connectivity in shaping system dynamic behavior. We hypothesize that circuits containing disynaptic feedforward inhibition in the nervous system may be candidates for interpreting upstream rate codes to g

关键词： CRG limit cycle neural coding Blending limit cycles precession Phase

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neural coding in the cat retina

Neural coding in the cat retina

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24th Annual International Conference of the Engineering-in-Medicine-and-Biology-Society/Annual Fall Meeting of the Biomedical-Engineering-Society (EMBS 2002 BMES)

作者： Troy, JB Northwestern Univ Dept Biomed Engn Evanston IL 60208 USA

ISBN: (纸本)0780376129

The output of the cat retina is conveyed to the brain by the axons of similar to170,000 retinal ganglion cells that together constitute an optic nerve. Ganglion cells come in a number of varieties with the result that the message conveyed along the nerve to the brain is partitioned into a number of components. In this paper some key discoveries about neural coding in the cat retina are reported and used to illustrate how efficient the retina is at encoding visual information.

关键词： neural coding retina vision

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THE STATE OF GUSTATORY neural coding

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CHEMICAL SENSES 1984年第3期8卷 264-264页

作者： SCOTT, TR UNIV DELAWARE DEPT PSYCHOLNEWARKDE 19711 UNIV DELAWARE INST NEUROSCINEWARKDE 19711

Debates on gustatory neural coding have been dominated by a small number of fundamental issues since the inception of the field in 1941. Three of these are discussed in this review: (1) are there basic tastes?(2) are there gustatory neuron types?(3) is the code for a taste read simultaneously across all participating neurons (across-fiber patterning), or is it confined to a selective channel composed of cells of one type (labeled-line or channeling)?No conclusions are drawn regarding (1), primarily because a universal definition of‘basic tastes’is lacking. It is concluded that gustatory neuron types are likely to exist after reviewing the issue from multiple perspectives and discovering recurring indications of neuron types from several. A firm conclusion, however, also awaits a widely accepted definition of what constitutes a neuron type. Issue (3) cannot yet be resolved for lack of definitive data, specifically whether the discharges of inhibited, unresponsive, or weakly responsive cells add to (signal) or detract from (noise) the neural code for a tast

关键词： taste neural coding neuron types

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Code Under Construction: neural coding Over Development

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TRENDS IN NEUROSCIENCES 2018年第9期41卷 599-609页

作者： Avitan, Lilach Goodhill, Geoffrey J. Univ Queensland Queensland Brain Inst Brisbane Qld 4072 Australia Univ Queensland Sch Math & Phys Brisbane Qld 4072 Australia

Developing animals must begin to interact with the world before their neural development is complete. This means they must build neural codes appropriate for turning sensory inputs into motor outputs adaptively as their neural hardware matures. We review some recent progress in the understanding of the relationship between neural coding and neural circuit development. We focus particularly on neural coding in the context of topographic maps and spontaneous activity, as well as receptive field and circuit development, drawing on examples from both mammalian visual cortex and fish optic tectum. Overall we suggest that neural coding strategies during development may be highly dynamic.

关键词： circuit development neural coding spontaneous activity receptive field topographic map Bayesian inference

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The effect of an exogenous alternating magnetic field on neural coding in deep spiking neural networks

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JOURNAL OF INTEGRATIVE NEUROSCIENCE 2018年第2期17卷 97-104页

作者： Guo, Lei Zhang, Wei Zhang, Jialei Hebei Univ Technol State Key Lab Reliabil & Intelligence Elect Equip Tianjin 300130 Peoples R China Hebei Univ Technol Key Lab Electromagnet Field & Elect Apparat Relia Tianjin 300130 Peoples R China

A ten-layer feed forward network was constructed in the presence of an exogenous alternating magnetic field. Results indicate that for rate coding, the firing rate is increased in the presence of an exogenous alternating magnetic field and particularly with increasing enhancement of the alternating magnetic field amplitude. For temporal coding, in the presence of alternating magnetic field, the interspike intervals of the spiking sequence are decreased and the distribution of interspike intervals tends to be uniform.

关键词： Spiking neural network neural coding reduced neuron model

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GENERALIZED MAHALANOBIS DEPTH IN POINT PROCESS AND ITS APPLICATION IN neural coding

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ANNALS OF APPLIED STATISTICS 2017年第2期11卷 992-1010页

作者： Liu, Shuyi Wu, Wei Florida State Univ Dept Stat Tallahassee FL 32306 USA

In this paper, we propose to generalize the notion of depth in temporal point process observations. The new depth is defined as a weighted product of two probability terms: (1) the number of events in each process, and (2) the center-outward ranking on the event times conditioned on the number of events. In this study, we adopt the Poisson distribution for the first term and the Mahalanobis depth for the second term. We propose an efficient boot-strapping approach to estimate parameters in the defined depth. In the case of Poisson process, the observed events are order statistics where the parameters can be estimated robustly with respect to sample size. We demonstrate the use of the new depth by ranking realizations from a Poisson process. We also test the new method in classification problems using simulations as well as real neural spike train data. It is found that the new framework provides more accurate and robust classifications as compared to commonly used likelihood methods.

关键词： Point process Mahalanobis depth Poisson process neural coding spike train

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Electrosensory processing in Apteronotus albifrons: implications for general and specific neural coding strategies across wave-type weakly electric fish species

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JOURNAL OF NEUROPHYSIOLOGY 2016年第6期116卷 2909-2921页

作者： Martinez, Diana Metzen, Michael G. Chacron, Maurice J. McGill Univ Dept Physiol Montreal PQ Canada

Understanding how the brain processes sensory input to generate behavior remains an important problem in neuroscience. Towards this end, it is useful to compare results obtained across multiple species to gain understanding as to the general principles of neural coding. Here we investigated hindbrain pyramidal cell activity in the weakly electric fish Apteronotus albifrons. We found strong heterogeneities when looking at baseline activity. Additionally, ON- and OFF-type cells responded to increases and decreases of sinusoidal and noise stimuli, respectively. While both cell types displayed band-pass tuning, OFF-type cells were more broadly tuned than their ON- type counterparts. The observed heterogeneities in baseline activity as well as the greater broadband tuning of OFF-type cells were both similar to those previously reported in other weakly electric fish species, suggesting that they constitute general features of sensory processing. However, we found that peak tuning occurred at frequencies similar to 15 Hz in A. albifrons, which is much lower than values reported in the closely related species Apteronotus leptorhynchus and the more distantly related species Eigenmannia virescens. In response to stimuli with time-varying amplitude (i.e., envelope), ON- and OFF-type cells displayed similar high-pass tuning curves characteristic of fractional differentiation and possibly indicate optimized coding. These tuning curves were qualitatively similar to those of pyramidal cells in the closely related species A. leptorhynchus. In conclusion, comparison between our and previous results reveals general and species-specific neural coding strategies. We hypothesize that differences in coding strategies, when observed, result from different stimulus distributions in the natural/social environment.

关键词： neural coding tuning envelopes behavior

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