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  • 1
    Electronic Resource
    Electronic Resource
    Dynamische Eigenschaften von Nervennetzen im visuellen System (1972)
    Springer
    Biological cybernetics 10 (1972), S. 64-77 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The preprocessing of optical information in the visual system takes place in the two-dimensional homogeneous nervous nets of the retina and the geniculate body. These networks can be considered as band-pass filters for space-dependent oscillations if the input stimuli are independent of time. If the synapses of the neurons have timefrequency dependent properties the performance of the system in the space domain, which is important for pattern recognition, is determined by the time dependence of input signal. For a description of these networks in this investigation the space spectrum for various values of the time frequency ω is used. The answers of real nervous nets can be interpreted by the model when the two-dimensional input signals are switched, flickered or moved. For this reason these dynamic stimuli are necessary for an analysis of the cortex. The theoretical combination of space- and time-dependent filtering is essential for an understanding of cortical transformations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292232
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  • 2
    Electronic Resource
    Electronic Resource
    On the classification of visual patterns: Systems analysis using detection experiments (1977)
    Springer
    Biological cybernetics 25 (1977), S. 121-130 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Behavioral experiments are indispensable for the analysis of biological systems for cognition and recognition. When these are carried out as detection experiments three types of description can be used for the problem of visual pattern recognition which allow conclusions to be drawn on the operating function of the system. Provided that the signals to be recognized have additive noise superimposed on them, system description is possible: 1. on the basis on the probabilities of recognition and of mix-up,—2. through the analysis of the transformation of distribution densities of the noise,—3. by means of the measurable distances of the patterns from each other in feature space.-The analysis of the distribution densities shows that the human visual system acts like a linear classifier in the classification of six geometrical patterns. The independence of the classification from intensity as well as the human reaction to alteration in the power spectrum of the noise support this result. Simulation experiments on a computer show the efficacy of various biological relevant parameters for the linear classification and suggest that a narrow band and probably feature specific filtering precedes the classification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365209
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  • 3
    Electronic Resource
    Electronic Resource
    On the analysis of the cat's pattern recognition system (1983)
    Springer
    Biological cybernetics 48 (1983), S. 115-124 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The objective of the paper is to determine in abstract terms the algorithms used by the cat detecting simple patterns and to quantify the contributions of the visual areas 17, 18, 19 for this task. The data incorporated in the algorithm are collected from behavioral experiments where the animals had to distinguish between two patterns. The patterns were superimposed with gaussian noise and the detection probability was measured. The resulting model describes pattern recognition in two steps: first extraction of features and second classification. The test of the validity of the model system was to predict the outcome of similar experiments but with different patterns. With the help of the model it is possible to deccribe the effect of a lesion in parametric form. This in turn gives some hints about the functions of the visual areas 17, 18, 19 for the specific fask, tested in the experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344395
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  • 4
    Electronic Resource
    Electronic Resource
    Informationsverarbeitung in homogenen Netzen von Neuronenmodellen (1968)
    Springer
    Biological cybernetics 5 (1968), S. 133-148 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Summary The interconnection structures of the peripheral part of the nervous system, which are considered here, are two-dimensional homogeneous networks with time and space dependent inputs and outputs. The principles of connection under consideration comprise lateral inhibition and facilitation. The transfer functions of those linear networks as well as the stability problem are investigated on a digital computer using different system parameters. A closed form solution is given for an infinitely large element density which describes the network properties. In this case an inhibition system acts as high pass filter on the spatial frequencies of the input, whereas a facilitation network acts as low pass filter. The properties of the networks and the transformations in case of moving patterns are analysed using the methods of systems theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00271247
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  • 5
    Electronic Resource
    Electronic Resource
    Characteristics of neuronal systems in the visual cortex (1987)
    Springer
    Biological cybernetics 56 (1987), S. 37-49 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The coupling complexity of cortical areas makes it very difficult to analyse them experimentally. Studies of model systems provide the possibility of adapting the analysis to the avaible data base and claborating the fundamental properties that depend on the structure of the system. We propose a model system of variable complexity that is spatially two-dimensional and time-dependent, uses feedback for iteration and smoothing, includes the mapping of the cortical networks and can be nonlinear as the case requires. Combining such elementary systems on the basis of neuroanatomical findings enables us to simulate cortical mappings and to interpret neurophysiological data. The decisive factor is that the dynamics of the system and the neuroanatomically based spatial coupling are closely connected with each other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333066
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  • 6
    Electronic Resource
    Electronic Resource
    Empfang gestörter Signale durch den schwachelektrischen Fisch Gnathonemus petersii (1971)
    Springer
    Biological cybernetics 9 (1971), S. 34-43 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Summary A short description of the transmitting and receiving organ of Gnathonemus petersii is followed by results of experiments carried out to measure the sensitivity of the receptors for external signals (communication) and for distortions of the own electric field (active object location) with and without additive noise. Possible principles of reception are synchronous, asynchronous and threshold receivers; further experiments indicate the threshold receiver to be the most probable structure. Treating the active object location as a problem of statistical communication theory yields for small disturbances to a generalized cross-correlator, which in this case behaves like a threshold receiver.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00272559
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  • 7
    Electronic Resource
    Electronic Resource
    Methoden zum Vergleich des Leistungsvermögens biologischer und technischer Systeme (1972)
    Springer
    Biological cybernetics 10 (1972), S. 1-16 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Summary In this work the methods of the communication theory for binary detection, multiple detection and extraction are applied to biological systems. It is the objective of this investigation to compare the performance of optimal and biological systems in receiving signals superimposed by noise. The required mathematical relations and methods of measurements are derived. In the second part of this work pattern recognition experiments (multiple detection) at the human visual system with stationary and time variant patterns are described. The comparison of the performance between optimal and biological system shows that the human visual system acts in a suboptimal way. From some other detection experiments it can be concluded that the recognition process is describable by spatial cross-correlation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00288779
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  • 8
    Electronic Resource
    Electronic Resource
    Analysis of neuronal networks in the visual system of the cat using statistical signals (1976)
    Springer
    Biological cybernetics 22 (1976), S. 7-20 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract If the input signals of the visual system in the cat are statistical patterns in space and time, a complete system analysis can be carried out. What counts here as a system are the neuronal networks between retina and recording site. In the case of linearity, one obtains the temporal impulse response functions at every point in the receptive field with the aid of correlation methods. The measuring time is about one minute. Some aspects of the procedure are explained in terms of examples. The method of measurement also makes it possible to determine the characteristic function of the system in time and space between different recording sites within the cortex. It is possible to specialize the procedure for analysing the stationary space dependent behaviour of neuronal networks. The extension of the analysis procedure allows a concise, relatively simple description for nonlinear systems in which linear and nonlinear subsystems can be separated. Besides this, there are no restrictions concerning the kind of nonlinearity. A second paper will present the detailed experimental application of these methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00340228
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  • 9
    Electronic Resource
    Electronic Resource
    Analysis of neuronal networks in the visual system of the cat using statistical signals — Simple and complex cells (1978)
    Springer
    Biological cybernetics 31 (1978), S. 175-185 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Superimposing additively a two-dimensional noise process to deterministic input signals (bars) the neurons of area 17 show a class-specific reaction for the task of signal extraction. Moving both parts of the signals simultaneously and varying the signal to noise ratio (S/N) the simple cells achieve the same performance as resulted from the psychophysical experiment. Type I complex cells extract moving deterministic signals (i.e. bars) from the stationary noise, whereas in the answers of Type II complex cells the statistical parts of the signals predominate. Considering the different cell types each as a series of a linear and a nonlinear system one obtains the cell specific space-time frequency and the amplitude characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337004
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    On the interpretation of optical illusions (1973)
    Springer
    Biological cybernetics 12 (1973), S. 111-115 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract If excited by stimuli adjacent in space and time, the optical system frequently perceives illusions in the form of apparent movements. These effects may be attributed to the dynamic properties of the retinal nerve nets. On the basis of a specific psychophysical experiment the mechanism underlying the generation of optical illusions is interpreted by the methods of systems theory and its use in systems analysis is discussed. It is shown that for the perception of apparent movements the transit times of the signals in the dendrites are particularly important.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00272467
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