Alexander Vidybida - Academia.edu (original) (raw)

Papers by Alexander Vidybida

Eprint Arxiv 0801 0250, Dec 1, 2007

Based on numerical simulation of Hodgkin and Huxley type neuron stimulated from many synaptic inp... more Based on numerical simulation of Hodgkin and Huxley type neuron stimulated from many synaptic inputs, an abstract concept of signal processing in individual neuron is proposed. In the concept proposed, neuron performs binding of synaptic inputs into a single output event, based on the degree of temporal coherence between the inputs. Inhibition serves as controlling factor of this type of binding.

Complexity, 2020

A method for analyzing sequential data sets, similar to the permutation entropy one, is discussed... more A method for analyzing sequential data sets, similar to the permutation entropy one, is discussed. e characteristic features of this method are as follows: it preserves information about equal values, if any, in the embedding vectors; it is exempt from combinatorics; and it delivers the same entropy value as does the permutation method, provided the embedding vectors do not have equal components. In the latter case, this method can be used instead of the permutation one. If embedding vectors have equal components, this method could be more precise in discriminating between similar data sets.

BioSystems 48 (1998) 263–267, 1998

Natural stimulus for a neuron is a sum of large number of unitary excitatory postsynaptic potenti... more Natural stimulus for a neuron is a sum of large number of unitary excitatory postsynaptic potentials (EPSP) slightly dispersed in time. We analyze, based on numerical solution of the Hodgkin and Huxley equations, how does the triggering ability of the compound stimulus depend on the relative timing of the EPSPs it comprises. The dependences found suggest that a neuron stimulated from many synaptic inputs can be treated as performing elementary binding function and that inhibition serves as a controller of that kind of binding. The transient process characterized by EPSP operates in this context as a short-term memory mechanism inherent to a single neuron.

Sensors and Actuators A: Physical Volume 107, Issue 3, 1 November 2003, Pages 233-237, 2003

Small chemical sensors are subjected to adsorption-desorption fluctuations which usually consider... more Small chemical sensors are subjected to adsorption-desorption fluctuations which usually considered as noise contaminating useful signal. Based on temporal properties of this noise, it is shown that it can be made useful if proper processed. Namely, the signal, which characterizes the total amount of adsorbed analyte, should be subjected to a kind of amplitude discrimination (or level crossing discrimination) with certain threshold. When the amount is equal or above the threshold, the result of discrimination is standard dc signal, otherwise it is zero. Analytes are applied at low concentration: the mean adsorbed amount is below the threshold. The threshold is achieved from time to time thanking to the fluctuations. The signal after discrimination is averaged over a time window and used as the output of the whole device. Selectivity of this device is compared with that of its primary adsorbing sites, based on explicit description of the threshold-crossing statistics. It is concluded that the whole sensor may have much better selectivity than do its individual adsorbing sites.

BioSystems (2017) 161, pp. 24-30, 2017

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Neurophysiology, Vol. 51, No. 3, May, 2019, 2019

A possible mechanism that provides increased selectivity of olfactory bulb projection neurons, as... more A possible mechanism that provides increased selectivity of olfactory bulb projection neurons, as compared to that of the primary olfactory receptor neurons, has been proposed. The mechanism operates at low concentrations of the odor molecules, when the lateral inhibition mechanism becomes inefficient. The mechanism proposed is based on a threshold-type reaction to the stimuli received by a projection neuron from a few receptor neurons, the stochastic nature of these stimuli, and the existence of electrical leakage in the projection neurons. The mechanism operates at the level of the single individual projection neuron and does not require the involvement of other bulbar neurons.

Journal of Theoretical Biology Volume 152, Issue 2, 21 September 1991, Pages 159-164, 1991

High selectivity (specificity) and sensitivity to natural or artificial stimuli which are normall... more High selectivity (specificity) and sensitivity to natural or artificial stimuli which are normally observed for biological systems can be realized in an ensemble composed of many cooperatively connected primary receptors. The cooperative interaction results in the formation of several stable states and a switching from one state to another is performed in a threshold manner. When any noise is absent the ensemble with a threshold can secure as high a selectivity and sensitivity as is desired. The presence of noise sets limits on the possible informational quality of a system because spontaneous switchings will occur. The question: What advantage as regards selectivity and sensitivity can a cooperative system with a threshold have is considered quantitatively as an example for a bistable chemical system. As a result it is established that a cooperative system may have much higher selectivity and sensitivity than its individual primary receptors.

International Journal of Neural Systems, Vol. 21, No. 3 (2011) 187–198, 2011

Information about external world is delivered to the brain in the form of structured in time spik... more Information about external world is delivered to the brain in the form of structured in time spike trains. During further processing in higher areas, information is subjected to a certain condensation process, which results in formation of abstract conceptual images of external world, apparently, represented as certain uniform spiking activity partially independent on the input spike trains details. Possible physical mechanism of condensation at the level of individual neuron was discussed recently. In a reverberating spiking neural network, due to this mechanism the dynamics should settle down to the same uniform/ periodic activity in response to a set of various inputs. Since the same periodic activity may correspond to different input spike trains, we interpret this as possible candidate for information condensation mechanism in a network. Our purpose is to test this possibility in a network model consisting of five fully connected neurons, particularly, the influence of geometric size of the network, on its ability to condense information. Dynamics of 20 spiking neural networks of different geometric sizes are modelled by means of computer simulation. Each network was propelled into reverberating dynamics by applying various initial input spike trains. We run the dynamics until it becomes periodic. The Shannon's formula is used to calculate the amount of information in any input spike train and in any periodic state found. As a result, we obtain explicit estimate of the degree of information condensation in the networks, and conclude that it depends strongly on the net's geometric size.

BioSystems 71 (2003) 205–212, 2003

Reverberating dynamics of neural network is modeled on PC in order to illustrate possible role of... more Reverberating dynamics of neural network is modeled on PC in order to illustrate possible role of inhibition as binding controller in the network. The network is composed of binding neurons. In the binding neuron model [BioSystems 48 (1998) 263], the degree of temporal coherence between synaptic inputs is decisive for triggering, and slow inhibition is expressed in terms of the degree, which is necessary for triggering. Two learning mechanisms are implemented in the network, namely, adjusting synaptic strength and/or propagation delays. By means of forced playing of external pattern, the network is taught to support dynamics with disconnected and bound patterns of activity. By choosing either high, or low inhibition, one can switch between the disconnected and bound patterns, respectively. This is interpreted as inhibition-controlled binding in the network.

Encyclopedia of Information Science and Technology, Third Edition, 2015

The brain ability to perform meaningful signal pro- cessing tasks related to perception, pattern ... more The brain ability to perform meaningful signal pro-
cessing tasks related to perception, pattern recogni-
tion, reasoning is normally attributed to large-scale
neuronal networks. The main signals involved in the
instantaneous neural processing are neural impulses,
and the units, which process impulses in a network,
are individual neurons. We now put a question: In the
context of higher brain functions, like perception, what
is a meaningful task a neuron performs with the signals
it receives? Another question: Does the inhibition exist
for taming neuronal activity only, or it can be endowed
with a more intelligent signal processing role? In
this article, we propose an abstract concept of signal
processing in a generic neuron, which is relevant to
the features/events binding well known for large-scale
neural circuits. Within this concept, action of inhibition
obtains its natural signal processing meaning.

Acta Mechanica 67, 183–190 (1987), 1987

The motion of a particle in the field of potential forces under conditions of large friction that... more The motion of a particle in the field of potential forces under conditions of large friction that has a component which is nonlinear with respect to the velocity is studied. It is shown that a periodic external force of small period results, under certain circumstances, in a modification of the initial potential function a term linear with respect to the deflection is added. Possible implications of this result for problems in physico-chemieal biology are discussed.

Physics Letters A Volume 108, Issue 3, 25 March 1985, Pages 170-172, 1985

The possibility of a drift of charged particles in a non-newtonian fluid by a spatially homogeneo... more The possibility of a drift of charged particles in a non-newtonian fluid by a spatially homogeneous time-periodic and non-sine-shaped electric field is proved theoretically. The phenomenon may be important in the transfer accompanied interaction between living cells and dispersive particles and also between intracellular organelles.

Biol. Cybern. 74, 537–542 (1996), 1996

Neuronal excitability under stimuli with a complex time course is investigated on the basis of th... more Neuronal excitability under stimuli with a complex time course is investigated on the basis of the numerical solution of the Hodgkin-Huxley equations. Each stimulus is composed of 100-1000 unitary excitatory postsynaptic potentials (uEPSP) that start randomly within a definite time window. Probability of initiating a spike [firing probability, FP(W)] as a function of the window width W is calculated by the Monte Carlo method. FP(W) has a step-like shape: it becomes equal to 1 for small W and almost vanishes as W exceeds some value Ws. The role of long-lasting somatic inhibition is analysed. Ws depends on the inhibition potential, but the step-like shape of FP is preserved. It is concluded that the capability of multisynaptic stimulation to cause a spike can be expressed in terms of temporal coherence between the synaptic inputs. Namely, the spike is initiated if the temporal coherence between active inputs is above a definite threshold. The threshold value can be effectively regulated by varying the inhibition potential.