Showing papers in "Kybernetika in 1967"

Quantification method of classification processes. Concept of structural $a$-entropy

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Brain and physics of many-body problems

Abstract: On the basis of a recent physical theory of many-body problems developped in our Institute, a model of the brain is formulated, and it is shown how some of its typical features, such as learning and memory processes, find therein a natural and simple explanation. In the Appendix a short surview of the necessary mathematical formalism is finally given.

Reverberations and control of neural networks.

Abstract: The simulation of neural networks, such as the brain cortex, which have a diffuse and rather uniform structure quite unlike the simple block-structure of extant computers, leads naturally to the study of functions and principles which only in part fall within the scope of Automata Theory. Systems of decision equations must be studied with a view especially to obtaining practical means for the prevision and computation of diffuse reverberations of wanted general characteristics, with the exclusion of all others. This amounts to deriving constraints on the allowed variability of the couplings among elements during learning processes, failing which the behavior of the simulator would become uncontrollable for practical purposes. A simple mathematical treatment is presented, which essentially linearizes these problems by an appropriate use of matrix algebra and permits a straightforward study of the wanted conditions, as well as of the controlling elements which may have to be added to the network.

[On the regulation of the position of the femur-tibial joint of the walking-stick insect Carausius morosus at rest and in motion].

Abstract: Das femorale Chordotonalorgan adaptiert nicht vollstandig. — Werden die femoralen Chordotonalorgane einer Korperseite operativ dauernd gespannt, weichen die Tiere auf einer senkrechten Laufflache in Richtung der intakten Korperseite von der Senkrechten ab. — Der Regelkreis zur Stabilisierung des Femur-Tibia-Gelenkes kann auf unterschiedliche Werte adaptieren. Daraus werden Ruckschlusse auf die einzelnen Glieder des Regelkreises gezogen. — Eine Operationstechnik zur Verlegung des Ansatzes der Receptorsehne des femoralen Chordotonalorganes von der dorsalen auf die ventrale Seite des Femur-Tibia-Gelenkes wird beschrieben. Auf diese Weise operierte Tiere bewegen die Femur-Tibia-Gelenke wahrend des Laufens nur, wenn die Tarsen einen Gegenstand beruhren. Sonst bleiben die Beine starr ausgestreckt. Sind die Tiere dagegen in Ruhe, beugen sie das operierte Bein in regelmasigen Abstanden. — Die Untersuchung der Tiere am Laufrad ergibt: Verhindert man das Ruckschwingen eines Beines, wird es beim Laufen nicht bewegt. Es erzeugt aber eine Kraft. Diese Kraft ist im intakten Bein groser als bei durchtrennter Receptorsehne und kleiner als bei dauernd gespanntem Chordotonalorgan. — Es wird ein Modell entwickelt, das die Steuerung des Fuhrungsgrosengebers fur die Bewegung eines Beines durch die bis jetzt bekannten Afferenzen aus Beinreceptoren abbildet.

Der Einfluß des Schirmpigmentgehalts auf die Helligkeits- und Kontrastwahrnehmung bei Drosophila Augenmutanten

Abstract: The function of the facet-separating pigments in the compound eyes of the fruitfly Drosophila melanogaster with hypernormal (se), normal (+), subnormal (wa), and missing (w) pigmentation was studied by investigation of: (1) the in-flight optomotor responses to movement of striped patterns with a mean brightness of 300 cd/m2, and (2) the retinal action potentials evoked by flashes in a program of .0003 cd/m2 average brightness. The pigment deficient mutants (wa, w) are less sensitive to the pattern contrast in the bright adapted state, and more sensitive to the flash intensity in the dark adapted state than either the wild-type (+) or the overpigmented mutant(se). These differences are complementary and can be explained by the increased translucency of the pigment cells. Thus the photoreceptors in the equally illuminated eyes of the normal and mutant animals +, se, wa, and w are expected to receive light in a ratio of about 1∶1∶7∶19. However the sensitivity of the receptors as well as the half-peak widths and the density of their visual fields are apparently independent of the eye pigmentation and seem to be equal at common levels of adaptation. The effects of omnidirectional excess light reaching the receptors of the pigment deficient mutants can be simulated in less translucent eyes: when certain amounts of background illumination were combined with the optomotor stimulus in the visual fields of the wild-type receptors it was possible to elicit the predicted “mutant behavior”.

Neural correlates of the optomotor response in the fly

Abstract: Studies of the optomotor response, the tendency to turn in response to a moving pattern, have yielded some understanding of the motion detection capabilities of the fly. We present data from extracellular microelectrode recordings from the optic lobes of the housefly, Musca domestica and the blowflies Eucalliphora lilaea and Calliphora phaenicia. Directionally selective and directionally nonselective motion sensitive units were observed in the region between the medulla and the lobula of all three species. Employing similar stimulus conditions to those used in the optomotor reaction studies, it was found that the response of the directionally selective units exhibited most of the characteristics of the optomotor response torque measurements. It is concluded that these units code the information prerequisite to the optomotor response and hence, that much data processing is achieved in the first few synaptic layers of the insect visual nervous system.

Some properties of the components of the Limulus ommatidial potential.

Abstract: The Limulus ommatidial potential, as recorded with intracellular microelectrodes, can be divided into three components. These components do not occur in the same portion of the ommatidium. During dark adaptation one can plot the height of the response evoked by a constant stimulus presented at regular intervals of time after the adapting light is removed. Hyperpolarizing current influences the shape of the curve obtained by this means. Increasing potassium ion concentration in the external medium reduces the height of the ommatidial potential. The steady component is decreased more by high potassium than the final component. Removing calcium ion from the medium abolishes the transient component.

On a classification of context-free languages.

Abstract: The set E of strings is said to be definable (strongly definable) if there is a context-free grammar G such that E is the set of all terminal strings generated from the initial symbol (from all non­ terminal symbols) of G. The classification of definable and strongly definable sets in dependence on minimal number of nonterminal symbols needed for their generation is given.

The torque-angle transfer function of the human eye.

Abstract: Sinusformig wechselnde Krafte werden am Auge angewandt, und die resultierenden Bewegungen werden mit Hilfe eines Beschleunigungsmessers gemessen. Dieser ist an einer Kontaktlinse befestigt. Die Veranderung der Grose und des Phasenwinkels der Augendrehung mit der Frequenz wird in Form eines Bode-Diagramms wiedergegeben. Ein mechanisches Modell, das aus linearen visco-elastischen Elementen besteht, wird verwendet, um das Augapfel-Muskel-System nachzuahmen. Die Parameter des Modells werden nach der Methode der besten Ubereinstimmung aus den Ubergangs-Charakteristika bestimmt. Die Beschleunigung-gegen-Zeit Kurve der Bewegung, die durch Anwendung einer stufenartigen Verdrehung am Auge verursacht wird, ist in guter Ubereinstimmung mit der vom Modell vorausgesagten. Die Drehwinkel-Ubergangsfunktion des unbelasteten Auges wird aus dem Modell durch Abzug des Tragheitsmoments der Kontaktlinse und ihrer Anhangsel abgeleitet. Ergebnisse fur Horizontal- und Vertikalbewegungen werden gesondert diskutiert. Vier kanonische und eine nicht-kanonische Form des mechanischen Modells sind angegeben. Angesichts der bekannten mechanischen Eigenschaften freiwilliger Muskel wird vermutet, das die nicht-kanonische Form am ehesten physikalischen Elementen in der Augenhohle entspricht. Drei Arten der Augenbewegung, die fur das Sehen wichtig sind, werden verglichen mit der Mechanik des Augapfel-Muskel-Systems. Es wird vorausgesagt, das eine Rotationsresonanz des Augapfels in der Pfanne erzeugt werden kann, wenn der Kopf in geeigneter Weise in Schwingungen gebracht wird. Die Natur der Muskelkrafte, die fur saccadische Bewegungen und unwillkurliche Fixierungstremore verantwortlich sind, wird aufgeklart.

Nervöse Wechselwirkung in der pupillomotorischen Bahn des Menschen

Abstract: The human pupillary response in one eye can be controlled by monocular light stimulation to either of the eyes. If both eyes are stimulated simultaneously the pupil reaction depeneds upon some combination of the signals originating in both eyes. Characteristic differences between the reactions to monocular and simultaneous binocular stimuli can yield information regarding the type of underlying neural interaction processes as well as the succession of neural events along the pupillomotor pathway. Qualitative comparison of the pupil reactions to monocular and binocular stimulation of sinusoidally varying intensity leads to the conclusion 1) that addition of the signals originating in both eyes occurs, and 2) that only linear transformation of the signals may take place after the addition. However, the quantitative relationship between the reactions to monocular and simultaneous binocular stimuli cannot be explained on the basis of this simple model; Data on pupil reactions to both sinusoidally modulated and flash light stimuli suggest that a mutual inhibition of the signals in the two optic nerves occurs before the addition of the signals.

On the Preemptive Priority Queues

Abstract: This article deals with the preemptive priority queues with single server in which the preempted items do not return to service and are lost. In the case of Poisson input and exponential service times the stationary distributions of the number of items of two priority classes are given. The Laplace-Stieltjes transform of the waiting time distribution has been derived.

To model or not to model.

Abstract: Self-improving control systems may belong to either of two categories, according to whether or not they embody an explicit model of the part of their environment with which they interact. The two forms of operation are discussed and compared, and it is shown that the two may be mathematically equivalent. The treatment also gives theoretical justification for a particular mode of operation for nonmodel-forming controllers.

Pooling of impulse sequences, with emphasis on applications to neuronal spike data.

Abstract: A mathematical model is presented that is supposed to describe those types of neuronal discharges which show a preponderance of short intervals, as well as one or more preferred intervals of a longer duration. It is assumed that via two channels impulses impinge upon a nerve cell and that each impulse gives rise to a response. The intervals between impulses in one channel are distributed according to an exponential, or an exponential-like, function; those in the other channel are distributed according to a monomodal, or a multimodal, function. The interval distributions and the expectation density (auto-correlation) functions of the model are in particular compared with data on thalamic neuron discharge patterns reported in the literature. The properties of superimposed time series of events would seem to be of a wider interest, stretching beyond the field of theoretical neurophysiology. It is indicated how the theory is of use in the detection of hidden rhythms in records which are composed of a mixture of different signals.

Discrimination Among Temporal Patterns of Stimulation in a Computer Model of a Coelenterate Nerve Net

Abstract: A simulation study is reported of the spread of excitation in a digital computer model based quite realistically on a coelenterate nerve net. The question posed is whether an elementary nervous system with randomly distributed properties can discriminate between time patterns of stimuli at the same average frequency. Forty-four temporal patterns of stimulation, each composed of seven stimuli in the same total period of time were applied to each of nine simulated nerve nets with each of eleven different distributions of four rates of decay of facilitation. The results may be summarized as follows:

Erkennung gesprochener Zahlworte mit Funktionsmodell und elektronischer Rechenanlage

Abstract: A simple function-model of the human ear is used to transfer the sound of the German spoken numbers into channel-time patterns, which are coded and fed into an electronic computer ER 56. For each number a time-normalized characteristic pattern is formed and stored in the computer. For recognition a simple matching program in the computer is used, to compare the time normalized average pattern of all 10 numbers with the individual time normalized pattern to be recognized. Using this method, 95% of more than 1000 numbers — spoken without special care — could be recognized correctly.

Stochastische und rhythmische Eigenschaften spontan auftretender Verhaltensweisen von Fischen

Abstract: A statistical model is presented exhibiting properties of time sequences of certain spontaneously occurring and mutually interdependent behavioural movements of a fish. The statistical description is derived from the theory of renewal processes. It is demonstrated that the probability of a movement to occur is a function only of the temporal distance to the movement that occurred immediately before. Models are developed which can be easily simulated by computer or built up in hardware technique.

Ein mathematisches Modell für die Komponente P III des Elektroretinogramms

Abstract: The temperature dependence of the negative component P III of the rabbit's electroretinogram has been studied in former experiments. A mathematical model of this component is expressed by the transfer function of a second order system. By means of electronic computations of the parameters a good fit to the experimental curves has been attained. The influence of different temperature (10–30° C) is reflected in the model by changes of 2 constants only. The 10 values of these changes are rather high (>2). Possibilities and limitations of the model are discussed.

Respiratory effects on the dynamics of the pupillary light reflex in man

Abstract: Konsensuelle Pupillenreaktionen auf Lichtblitze wurden mit dem Verfahren der Infrarot-Reflexphotometrie an 10 gesunden Versuchspersonen registriert. Die Latenzzeit sowie die wichtigsten Kennzeiten des Reflexablaufes wurden ausgemessen und vom Zeitpunkt des Lichtreizes her der mitregistrierten Atmung zugeordnet. Bei Spontanatmung zeigen die Kennwerte des Pupillen-Lichtreflexes folgende Anderungen: inspiratorisch (Lichtreiz wahrend der Inspiration) werden die Latenzzeit (t L ) verlangert, die Kontraktion beschleunigt (Kontraktions-Halbwertszeit t K/2 und Kontraktionszeit t K verkurzt), das Ausmas der Pupillenverengung (Amplitude A) reduziert und die Wiedererweiterung verzogert (Dilatations-Viertelwertszeit t D/4 verlangert). Die grose Variabilitat in den respiratorischen Schwankungen von t D/4 wird so erklart, das die Wiedererweiterung einem doppelten Einflus von Seiten der Einatmung unterliegt: a) einem fruheren Effekt, der bald nach dem Lichtreiz den Reflexablauf im Sinne einer langsamen Wiedererweiterung modifiziert, und b) einem spaten Effekt, der direkt in den Verlauf der Wiedererweiterung beschleunigend eingreift. Bei willkurlich verlangsamter Atmung sind die respiratorischen Einflusse auf die Latenzzeit (t L ) vermindert, die auf t D/4 jedoch verstarkt. Dies darf so gedeutet werden, das die Latenzzeit mehr von der spontanen Tendenz des Atemzentrums, der Verlauf der Wiedererweiterung hingegen starker von dem Atemablauf unmittelbar abhangt. Diese Deutung wird durch die Resultate bei Atemstillstand gestutzt. Das Konzept der „kollektiven Merkmalsverschiebung” nach Drischel wird eingehend diskutiert. Die strenge Kopplung zwischen verschiedenen Merkmalen des Pupillen-Lichtreflexes, die Drischel (1957) sowohl in variationsstatistischen Untersuchungen an einer grosen Personengruppe wie auch bei Einwirkung von Pharmaka fand, gilt nicht fur intraindividuelle, atemrhythmische Veranderungen. Es finden sich im Gegenteil sehr ausgepragte „differenzierte Merkmalsverschiebungen”. Gerade dies last die Pupillographie als einen besonders interessanten Indicator fur vegetative Tonusschwankungen erscheinen.

Amplitude modulation of the retinal ganglion cell impulses.

Abstract: Die Netzhaut decerebrierter Katzen wurde mit sinusformig moduliertem Licht gereizt und die in den Ganglienzellen ausgeloste Erregung extracellular registriert. Amplitude und momentane Frequenz der Aktionspotentiale andern sich sinusformig und besitzen zueinander eine Phasenverschiebung von 180°. Die Phasenverschiebung ist unabhangig von der Frequenz des Reizlichtes, die im Bereich von 0,1–10 Hz geandert wurde. Anhand von Kontrollmessungen wurde gezeigt, das die Amplitudenanderung der gemessenen Aktionspotentiale auf Anderungen des Membranpotentials beruht.

A simple non-linear theory of color perception and contrast effects.

Abstract: Evidence is presented for a simple model of the visual system, assuming that information processing is performed by Fechner type responses at all levels of neural interconnections. Red-green, yellow-blue and white-black opponentcolor responses are built up at the retinal level by linear algebraic summations of the logarithms of the excitation energies, that are produced in red, green and blue sensitive photoreceptors. Spacetime correlations are obtained by further nearly linear algebraic summations of the opponent-field responses in separate opponent-color response channels. This model provides a good first approximation for the description of various color vision phenomena, as the perception of brilliance and chromaticity of single colors, brilliance contrast, color induction, and Land's two color projections.

[The proposition of unequivocality and uncertainty, a contribution to the concept "useful information"].

Abstract: The main purpose of this work is to give axioms for the uncertainty measure which was introduced by Bongard [1].

A note on some distributions for nonlinear switching elements with finite dead time.

Abstract: Ricciardi et al. [3] have obtained the output distribution functions of a nonlinear switching element with a Poissonian sequence of impulses at the input. They have studied certain limiting properties of these distribution functions. However, certain limiting properties of these distributions become more obvious if one studies the underlying stochastic processes of these distributions. Further, the methods used by Ricciardi et al. for the derivation of the distribution functions and their limiting properties are quite involved. It might perhaps be useful to derive the main results of their paper by alternative simpler methods and point out the underlying stochastic processes more clearly.

Adaptive Control with Finite Settling Time

Abstract: This paper deals with a discrete selfadjusting filter forming a convenient control signal from a given command signal in order to achieve the desired state of the con­ trolled variable in a finite time period. The problem consists in modelling the gradient of the modified mean square error in a transfer function form. Because of the open-loop control used in our case, the plant transfer function need not to be known (the plant identification being unnecessary).