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intensity coding AND THE DYNAMIC-RANGE PROBLEM

HEARING RESEARCH 1988年第3期34卷 267-274页

作者： VIEMEISTER, NF Department of Psychology University of Minnesota Minneapolis 55455.

The psychophysical data on intensity discrimination indicate that certain schemes are unlikely as general intensity codes at the level of the auditory nerve and indirectly suggest that the most likely code is one based upon the firing rates of frequency-localized groups of fibers. A detection-theory analysis of a rate-based intensity code indicates that information from very few fibers can, if the information is appropriately combined, account for psychophysical discrimination even at high intensities. This suggests that fibers with similar CFs can code intensity over a wide range and that complex spectra can be represented at the level of the auditory nerve by a rate-CF code over the dynamic range of hearing. The analysis also indicates, however, a substantial discrepancy between the psychophysical data on the dependence of discrimination thresholds on level and the predicted discrimination behavior of a representative population of auditory nerve fibers. Thus, if intensity coding is based on localized firing rate, this fundamental psychophysical behavior does not result solely from peripheral processes.

关键词： Dynamic range intensity coding intensity discrimination

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intensity coding AND LUXOTONIC ACTIVITY IN THE GROUND-SQUIRREL LATERAL GENICULATE-NUCLEUS

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VISION RESEARCH 1987年第12期27卷 2073-2079页

作者： GUR, M Department of Biomedical Engineering Technion Israel Institute of Technology Haifa.

The responses of contrast-sensitive cells in the ground squirrel LGN were studied. In most cells the response to an on-off stimulus was comprised of two components: a sustained on and a transient on-off. The sustained component amplitude was a power function of the light intensity and disappeared altogether at low temperature while the transient component was insensitive to the light intensity and to a drop in temperature. These cells were also luxotonic;they increased their average firing rate when the intensity of a steady stimulus was increased. The possible relation to the luxotonic activity to the diurnal nature of the ground squirrel is discussed.

关键词： Ground squirrel Lateral geniculate nucleus intensity coding Luxotonic activity

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intensity coding IN PRIMATE VISUAL-SYSTEM

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EXPERIMENTAL BRAIN RESEARCH 1978年第2期31卷 163-177页

作者： BARLOW, RB SNODDERLY, DM SWADLOW, HA RETINA FDN EYE RES INST BOSTON MA 02114 USA

The pupil reflex and the discharge of LGN [lateral geniculate nucleus] cells of the awake macaque [Macaca fascicularis] were measured under stimulus conditions that yielded evidence for wide-range intensity coding in human psychophysical experiments. Ganzfeld flashes of white light were delivered under dark-adapted conditions to the surgically immobilized eye of the monkey while the other eye was observed by IR. Three-second flashes elicited a consensual pupil reflex that was graded from -8 to 0 log lamberts (L), indicating that the optic nerve fibers are capable of coding at least an 8 log-unit range of light intensity. In the physiological experiments, shorter flashes (0.1-0.5 s) but otherwise indentical conditions elicited monotonically graded responses from one type of LGN cell over the photopic range of -5 to 0 log L. Responses from other types of LGN cells were also graded over wide ranges but had different thresholds and, in some cases, nonmonotonic intensity-response functions. Latency of the excitatory LGN responses decreased with increasing intensity according to a power function with slope of -0.08. The pupil reflex and the LGN cell excitatory responses approximated power functions of light intensity with exponents of 0.22 and 0.14-0.29, respectively. The range of intensity coding found for single LGN cells was the widest yet reported for diffuse stimuli.

关键词： intensity coding Ganzfeld illumination Lateral geniculate nucleus Pupil reflex Response latencies

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intensity coding in olfactory receptor cells

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Seminars in Cell and Developmental Biology 1994年第1期5卷 47-54页

作者： Trotier, Didier Laboratoire de Neurobiologie Sensorielle F-91305 Massy 1 Avenue des Olympiades France

Olfactory receptors code the concentration of stimulating molecules into an impulse frequency message. Patch-clamp recordings have now demonstrated, in the olfactory receptor cell membrane, a number of membrane conductances. Some of them are gated by odorants, in the cilia, and depolarize the cell through cAMP- or IP3-sensitive channels, depending on the species. Other conductances are activated by membrane depolarization and/or an increased intracellular Ca²⁺ concentration;they participate in oscillating membrane potential changes during impulses and post-spike after-polarizations, and control the repetitive firing. Original data relative to the resting potential and the impulse frequency coding of the odorant concentration are presented. © 1994 Academic Press Ltd.

关键词： intensity coding Membrane currents Olfaction Receptor cells Receptor potential

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Olivocochlear projections contribute to superior intensity coding in cochlear nucleus small cells

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JOURNAL OF PHYSIOLOGY-LONDON 2022年第1期600卷 61-73页

作者： Hockley, Adam Wu, Calvin Shore, Susan E. Kresge Hearing Res Inst Dept Otolaryngol Ann Arbor MI 48109 USA Univ Michigan Dept Mol & Integrat Physiol Ann Arbor MI 48109 USA Univ Michigan Dept Biomed Engn Ann Arbor MI 48109 USA

Understanding communication signals, especially in noisy environments, is crucial to social interactions. Yet, as we age, acoustic signals can be disrupted by cochlear damage and the subsequent auditory nerve fibre degeneration. The most vulnerable medium- and high-threshold-auditory nerve fibres innervate various cell types in the cochlear nucleus, among which the small cells are unique in receiving this input exclusively. Furthermore, small cells project to medial olivocochlear (MOC) neurons, which in turn send branched collaterals back into the small cell cap. Here, we use single-unit recordings to characterise small cell firing characteristics and demonstrate superior intensity coding in this cell class. We show converse effects when activating/blocking the MOC system, demonstrating that small-cell unique coding properties are facilitated by direct cholinergic input from the MOC system. Small cells also maintain tone-level coding in the presence of background noise. Finally, small cells precisely code low-frequency modulation more accurately than other ventral cochlear nucleus cell types, demonstrating accurate envelope coding that may be important for vocalisation processing. These results highlight the small cell olivocochlear circuit as a key player in signal processing in noisy environments, which may be selectively degraded in ageing or after noise insult. Key points Cochlear nucleus small cells receive input from low/medium spontaneous rate auditory nerve fibres and medial olivocochlear neurons. Electrical stimulation of medial olivocochlear neurons in the ventral nucleus of the trapezoid body and blocking cholinergic input to small cells using atropine demonstrates an excitatory cholinergic input to small cells, which increases responses to suprathreshold sound. Unique inputs to small cells produce superior sound intensity coding. This coding of intensity is preserved in the presence of background noise, an effect exclusive to this cell type in the cochle

关键词： cochlear nucleus intensity coding olivocochlear small cell cap

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RELIABILITY OF CHEMORECEPTOR CELL RESPONSE .1. intensity coding BY PATTERN AND RESPONSE MAGNITUDE WITH A COMPARISON OF ANALYTICAL METHODS

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JOURNAL OF COMPARATIVE PHYSIOLOGY A-NEUROETHOLOGY SENSORY NEURAL AND BEHAVIORAL PHYSIOLOGY 1994年第1期175卷 95-105页

作者： MERRILL, CL VOIGT, R ATEMA, J BOSTON UNIV MARINE PROGRAM MARINE BIOL LAB WOODS HOLE MA 02543 USA

1. To determine reliability of stimulus intensity coding we measured the response variability of 30 hydroxy-1-proline sensitive chemoreceptor cells from antennules of Homarus americanus. First, cells were tested with 5 repeated presentations of 10(-5)M and 10(-4)M hydroxy-1-proline. Then a stimulus response function was determined in each cell from 10(-6) to 5 x 10(-4)M in half log steps. 2. Population mean responses to repetitive stimulation showed little variability and mean stimulus response functions increased monotonically. In contrast, most individual cells showed a high response variability and no single cell stimulus-response function increased monotonically. The greatest response variability occurred between different cells. 3. Mean response magnitude of a 30 cell population allowed reliable discrimination between 10(-5)M and 10(-4)M hydroxy-1-proline for each of the 5 repetitions. It also allowed discrimination of all concentrations of hydroxy-L-proline tested. Across-fiber response patterns also differed significantly with concentration while they remained relatively stable with repetition of the same stimulus. 4. We applied different analytical methods to test the reliability of response magnitude and across-fiber pattern as possible codes for intensity discrimination. We demonstrated that a random population of rather unreliable receptor cells could provide remarkably reliable intensity information to the CNS based on response magnitude or across-fiber pattern.

关键词： CHEMORECEPTOR RESPONSE RELIABILITY intensity coding HYDROXY-L-PROLINE LOBSTER

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Dendritic integration in olfactory sensory neurons: A steady-state analysis of how the neuron structure and neuron environment influence the coding of odor intensity

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JOURNAL OF COMPUTATIONAL NEUROSCIENCE 1998年第3期5卷 243-266页

作者： Vermeulen, A Rospars, JP Inst Natl Rech Agron Unite Biometrie F-38031 Grenoble France Inst Natl Polytech Grenoble F-38031 Grenoble France

Response properties of the receptor potential at steady state were analyzed in a biophysical model of an olfactory sensory neuron embedded in a multicell environment. The neuron structure was described as a set of several identical dendrites (or cilia) bearing the transduction mechanisms, joined to a nonsensory part-dendritic knob, soma, and axon. The different ionic compositions of the media surrounding the neuron sensory and nonsensory parts and the extraneuronal voltage sources, which both result from the presence of auxiliary cells, were also taken into account. Analytical solutions were found to describe how the receptor potential at the nonsensory part responds to a uniform change in the odorant-dependent conductance resulting from odorant stimulation of the sensory dendrites. We investigated the influence of various geometrical and electrical parameters on the receptor-potential response in the classical model neuron within a homogeneous environment and in the model neuron surrounded with auxiliary cells. First, it was found that the maximum amplitude of the receptor potential is independent of the neuron structure in the absence of auxiliary cells but not in their presence. In the latter case, the amplitude decreases with the length and number of sensory dendrites and with the input resistance of the nonsensory part. Second, the sensitivity (as measured by the increase in membrane conductance at half-maximum response) of the neuron model in the absence of auxiliary cells is higher, but its dynamic range is narrower than in their presence. The dynamic range is wide and the sensitivity low when the input resistance of the nonsensory part is small and the sensory dendrite is unbranched. Both sensitivity and dynamic range are higher for a longer dendrite. These results help understand the morphology of insect olfactory sensilla and can be generalized to other neuron types.

关键词： olfactory sensory neuron intensity coding receptor potential cable equation single neuron modeling

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coding OF ODOR intensity

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BIOSYSTEMS 1993年第1期31卷 15-38页

作者： LANSKY, P ROSPARS, JP INRA BIOMETRIE LABF-78026 VERSAILLESFRANCE ACAD SCI CZECH REPUBL INST PHYSIOLCS-14220 PRAGUE 4CZECHOSLOVAKIA

A model for coding of odor intensity in the first two neuronal layers of olfactory systems is proposed. First, the occupation and activation by odorant molecules of receptor proteins of different types borne by the first order neurons are described as birth and death processes. The occupation (birth) rate depends on the concentration of the odorant, whereas the probability of activation of an occupied receptor depends on the type of the odorant. Second, the spike generation mechanism proposed for the first order neuron depends on the level of the generator potential evoked by the activated receptors and on a time-decaying threshold which is reset to infinity after each spike. The various resulting stochastic regimes of firing activity at different concentrations are described. Third, each second order neuron is influenced by excitation coming from numerous first order neurons, lateral inhibition from other second order neurons, and self-inhibition. All these incoming signals are integrated at the second order neuron. The firing activity of the first and second order neurons is modeled by a first passage time scheme. For both types of neuron the shapes of the curves predicted by the model for the mean firing frequency as a function of stimulus concentration are shown to be in accordance with available experimental results.

关键词： NEURONAL MODEL MEMBRANE POTENTIAL intensity coding OLFACTION STOCHASTIC PROCESS

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Emulation of auditory senses depending on chaotic dynamics of threshold switching memristor

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InfoMat 2023年第10期5卷 53-63页

作者： Junwei Yu Fei Zeng Qin Wan Ziao Lu Feng Pan Key Laboratory of Advanced Materials(MOE) School of Materials Science andEngineeringTsinghua UniversityBeijingthe People's Republic of China2Center for Brain Inspired ComputingResearch(CBICR)Tsinghua UniversityBeijingthe People's Republic of China

Emulating the auditory sense is a significant challenge in terms of both integration and energy consumption for handling complicated spatiotemporal ***,we demonstrate how to utilize the chaotic dynamics of a threshold switching memristor,which usually acts as a leaky integrate and fire neuron in the neuromorphic network,to encode the frequency and amplitude in auditory *** fabricate a Pd/Nb/NbOx/Nb/Pd memristor domi-nated by the Poole-Frankel conduction mechanism,set its state at the edge of chaos,and stimulate it using periodic *** memristor's responses to the perturbation frequencies can be categorized into three *** are phase locking with linear phase-frequency rela tionships,and one has a hyper-bolic spike number-frequency *** memristor system also enables intensity coding and tonotopy by modulating the response spikes in either the locked phase or spike *** on the emulation of these two features,the memristor system demonstrates sound location and frequency *** study suggests a novel routine for handling the auditory and visual senses using threshold-switching memristor arrays to enhance the efficiency of neuromorphic networks.

关键词： auditory senses chaotic dynamics intensity coding phase locking sound location thresholdswitching memristor

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Electrical circuitry of an insect olfactory sensillum

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NEUROCOMPUTING 2001年 38卷 1011-1017页

作者： Vermeulen, A Rospars, JP Royal Netherlands Naval Coll NL-1781 AC Del Helder Netherlands INRA Unite Biometrie F-78352 Jouy En Josas France

A biophysical model of an insect olfactory sensillum in steady-state conditions is presented. The model has two distinguishing features. Firstly, it describes analytically the extracellularly recorded potential, thus closing formally the gap between theoretical models and experimental results. Secondly, it integrates in a single description two extreme models previously investigated: that of the classical neuron located in a homogeneous environment and that of the neuron surrounded with auxiliary cells. The generalized model presented gives the opportunity of studying the response properties of the neuron to odors at various concentrations in a broader context. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词： olfactory sensory neuron sensillum membrane potential single neuron modelling intensity coding

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