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M S Livshits

Publications and source records attributed to M S Livshits.

17 recordsLinked to original sources
PubMedDate not supplied

[Hypothesis on acoustic receptive fields].

A hypothesis of acoustic receptive fields is studied, which is based on the fact that the cochlea of the internal ear is a wave guide with traveling waves and the resonance in the critical layer. When a harmonic sound influences the ear, the traveling wave reaches the critical layer for the corresponding frequency and generates there a train of decaying waves about 25 periods in duration, which form a steep slope of the envelope. The funnel-shaped convergence of all neurones innervating the acoustic receptors of the Corti organ along the slope of the envelope gives rise to acoustic receptive fields. The hypothesis is consistent with some other experimental data. Such an acoustic receptive field makes it possible to use the whole train of waves in the critical layer to measure the frequency of the acting sinusoidal sound with the greatest possible accuracy. Similarly, a high accuracy of recognition of short-time sound pulses is provided, which could not be explained earlier.

Acoustic Stimulation↗
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[Terrain observation by the horseshoe bat Doppler echolocator].

Results of further studies of physical bases of surroundings observations with Rhinophidae echolocator are presented. The observation is carried out due to the presence of pointed down irradiation diagram petal of its probing impulse. The frequency shift and devation of the signal, reflected from elementary surroundings region, induced by Dopler effect, are calculated. It is shown that the presence in the frequency threshold curve of Rhinophidae auditory system of a narrow-tuned filter in the location frequency region and control of the frequency of eminated impulse during flight provide for a response of the auditory system to the signal reflected from each point of surroundings. The resolution thus obtained is evaluated. A technique is suggested for experimental test of the work of the system for surroundings observation.

Animals↗
PubMedDate not supplied

[The problem of using correlation methods in brain function].

In a series of publications, the author used the correlation hypothesis to explain the main mechanisms of functioning of bat and dolphin echo locators. A good fit of calculated parameters to experimental data was shown. In this work, by the example of generalization of the recognition problem, the use by the brain of correlation methods for solving more general problems independently on the modality of sensor signals was analyzed. In favor of the hypothesis that correlation methods are widely used in brain functioning are the data presented in the paper, which prove that an associative neuron is a suitable analog computer. It is suited for rapid "computation" of the intercorrelation function of discrete input and reference signals. The set of weighting coefficients of neuron synaptic inputs serve as such signals. The pool of associative neurons determines the values on the correlation function in the required range by changing the "numbers" of inputs from neuron to neuron at which discrete signals arrive.

Animals↗
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[Explanation of octave and diplacusis effects].

The study is based on the model of sound perception that involves two systems of measuring the frequency of the sound being perceived. The system of analyzing the periodicity of spike sequence in axons of neurons innervating the internal auditory hair cells excited by the running wave is less precise, but it provides the estimation of the frequency of any periodical sounds. Exact measurement of the frequency of the sinusoidal sound occurs from the spikes in axons of neurones innervating the internal hair cells of the auditory reception field, which uses the entire train of waves excited by this sound in the critical layer of the waveguide of the internal ear cochlea, which corresponds to the frequency of the sound. The octave effect is explained in terms of the fact that the spectrum of frequencies of speech sounds, singing and music coincides with the region of the audibility range in which the impulses of the auditory nerve fibers are synchronized by incoming signals. The octave similarity, i.e., the similarity in the sounding of harmonic signals, whose frequencies relate as even numbers (2:1, etc.), is explained by an unambiguous match between the sound frequency and pulse rate in auditory fibers coming from the auditory reception field. The presence in the brain posterior tubercles of multipeak neurons whose peaks are in octave ratio, confirm the crucial role of the system of exact measurement of frequency in the phenomenon of octave similarity. The phenomenon of diplacusis, which is particularly pronounced in persons with Menier disease, is caused by changes in the position of the auditory reception field in the diseased ear as compared with the healthy ear. The alternating switching of reception from one ear to the other is related to a disturbance of the unitary image of pitch.

Acoustic Stimulation↗
PubMedDate not supplied

[Letter: Work of the impulse section of the horseshoe bat echolocator].

Peculiarities of location impulse of Rhinolophidae bring about a distinctive combination of dopler and impulse parts working almost independently, in its locator. In particular the range of the effect of impulse locator connected with the presence of LFM splash in the end of location cry is determined by the value of the period of its repetition. The existence of a long monofrequent part of locaion impulse providing the work of acholocator dopler part due to its narrow bands presents only a comparatively small obstacle to the impulse locator.

Animals↗
PubMedDate not supplied

[Correlation model of object recognition by echolocating animals].

The model proposed in an attempt to find out physical bases of object perception during echolocation. It is shown that echolocational perception can be provided with correlational treatment of corresponding signals. The character of objects is determined by the comparison by echo probing accepted in the given cycle with typical distortions remembered in the course of individual experience of the animal. The distortions take place during the reflection of the probing impulse from these or those objects. "Binding" of the objects according to distance may be carried out by using the choice of typical distortions for corresponding correction of the copy of probing impulse, serving as a bearing signal of distance correlometer. The response of correlometer to the echo from correctly perceived target increases. The block-scheme of such correlation perception during echolocation is given. Performance of some experiments allowing to check and refine the model considered.

Animals↗
PubMedDate not supplied

[Phenomenological model of the system for exact determination of target direction by the bat echolator].

A functional scheme of correlation treatment of an echosignal during the determination of a direction to the target by rats echolator is considered. The scheme proceeds from a suggestion that for an exact measurement of angle coordinates of the target the rat applies a location method of unisignal zones resulting from the pulsation of direction diagram when LFM impulse is emitted. Some considerations in favour of the suggested phenomenological model are presented. An experimental set-up which permits to test and specify the model is proposed.

Animals↗
PubMedDate not supplied

[Loudness measurement and automatic control in the acoustic analyzer].

A block diagram of a hearing system is presented in which external hair cells are used to measure the loudness level and to adjust automatically internal hair cells. This system may assure an optimal function of the basic acoustic systems responsible for sound analysis. The data presented form a theoretical foundation for an adequate physiological interpretation of the recruitment phenomenon recorded in certain forms of neurosensory hypoacusis.

Hair Cells, Auditory↗
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[Modeling of auditory mechanisms of pitch perception].

A hypothesis of two subordinately interconnected pitch perception systems is put forward and described. The leading system is responsible for the analysis of periodical sequences of spikes along audioneurons whose generation moments are synchronized by the acting sound oscillations. This system allows measuring of any periodical sound--simple or complex--including the residual sound. However, the system of periodicity analysis does not ensure the experimentally determined precision of pitch change perception. It is shown that the signal distribution along the basilar membrane enables the activation of the second system which analyses the spatial--temporal image by means of a great number of well innervated internal receptor cells. This system functioning is characterized by small values of differential threshold pitches, since as a discriminatory characteristic a curt decline of the basilar membrane oscillation envelope is used which is formed after a prolonged sinusoidal sound.

Basilar Membrane↗
PubMedDate not supplied

[Inner ear cochlear processes].

The processes accompanying the propagation across the basilar membrane (BM) of waves from a wide-band sound signal have been analyzed by physical methods. Particular emphasis in placed on the fact that BM is a low frequency filter. The characteristics of wave envelope from each of the sinusoidal components of the signal are given. The use of a simple mechanical model makes it possible to explain an initial increase in these envelopes. The steep slope of the envelope in its terminal part is explained in terms of the lighthill hydrodynamic model of cochlea. This provides a theoretical basis for adequate description of the periphery of the ear analyzer, with allowance for the active role of external auditory hair cells (EHC). Further research is needed to solve the problem completely. This is dictated by the complexity of the oscillatory system (BM in the region of the critical layer of cochlea plus EHC) and by its interaction with the autoregulation system in the air analyzer, which is described elsewhere.

Basilar Membrane↗
PubMedDate not supplied

[Automatic regulation in the auditory analyzer and the phenomenon of accelerated growth of loudness].

Physical analysis of the ear periphery structure and the data on loudness perception have been used to develop a model of loudness measurement and self-control in the hearing analyzer. The experimental results obtained recently by different researchers are shown to confirm that the basic ideas of this model are reasonable, and the model is of considerable heuristic importance. The author provides treatment of the main hearing "paradox", that is the existence of a wide dynamic range of loudness perception for a narrow range of afferent pulsation in auricular nerve fibers. A simple explanation is found for the so-called adaptation phenomenon. The explanation of the phenomenon of loudness increase acceleration typical for many forms of neurosensory hypoacousis opens up new perspectives in the diagnostics and treatment of these diseases.

Adaptation, Physiological↗
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[Model of the system for stabilizing the frequency of the echosignal of the Rhinolophus locator].

Physical analysis of anatomic, physiological and behavioural data pertaining to the work of Rhinolophidae echolocator is carried out, results of spectral analysis of its probing impulse are analysed. On this basis the working mechanism of sound emitting apparatus is proposed. A phenomenological model of the frequency stabilization system of the signal reflected from a located object is constructed. This stabilization is carried out by the compensation of Doppler shift of the echo frequency by a change of the generated impulse frequency. Due to the application of a differential method the model provides for potential accuracy of tuning, and its work does not depend on the value of a reflected signal and its sufficiently small changes which is in agreement with the experiments.

Animals↗
PubMedDate not supplied

[Calculation of potential accuracy in measuring the angular coordinates of targets by the echolocator of bats using the equal-signal zone method].

Potential accuracy in measuring the course to a target is calculated. This accuracy is physically achievable it the hypothesis that an accurate measurement of angular coordinates of the target of bat's echolocator is realized by the method similar to that of equally signaling zone in radiolocation is true. Possible application of such a method is based on the "pulsation" of direction diagram in the course of radiation of the probing impulse. In this case crossing of partial diagrams of radiation corresponding to high- and low-frequancy regions of the impulse form the equally signaling zine. If the target is in this direction the amplitudes of autocorrelation functions formed by corresponding regions of reflected and probing impulses will be equal. The minimal error of the method is limited by the optimum duration of each of the compared correlation functions, which forms the basis for derivation of the formula evaluating this error. Numerical calculation of the accuracy of measurements of the angle achievable for the echolocator of Myotis blythi is performed by this formula proceeding from average experimental values of the echolocator characteristics. The model under consideration is shown to agree with a number of experimental data.

Animals↗
PubMedDate not supplied

[Explantation of residual effect].

The direct spatial-temporal description of oscillations of the internal ear basilar membrane, arbitrarily called "oscillographic vision" of these oscillations, made it possible to create a model for two systems of auditory perception of sound pitch [1]. On the basis of this model, the residual effect is explained by the action of the main system, the system of periodicity analysis. A procedure of calculating the zone of occurrence of the residuum is described. The predominance of the complex of low-frequency constituents of the residual sound is explained. A qualitative and a quantitative description of high-frequency rectangular pulse shifts induced by the action of the fine structure of these pulses are given. The assumption is made that these results can be used for comparing the accuracy of the two systems of sound pitch perception.

Auditory Perception↗