Characteristics of neuronal systems in the visual cortex

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 available data base and elaborating 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 …

Information processing in nuclear magnetic resonance imaging.

An extended image analysis and classification system is presented to discuss the principal composition of the components as well as the methods of its realization in the field of reference based NMR diagnostics and tissue characterization.

On Information Processing in the Cat’s Visual Cortex

We assume that the visual system serves for orientation in space, recognition of objects and the interpretation of scenes and scene sequences. This task breaks up into a series of partially interdependent subproblems which are solved by some 13–15 usually retinotopically organized areas. So far it has not been possible to correlate functions and areas unequivocally. One reason for this could be the inadequacy of the questions posed as a basis for experiments. However, we think it more likely that correlating a function with an area is, as a rule, inadmissible since the degree of the coupling in the whole system does not permit a simple divsion. Rather the type and degree of coupling determi…

David Marr: A Theory for Cerebral Neocortex

This paper is an important contribution to the understanding of the visual system, it contains a part of those ideas which have become the commonly accepted basis of current research. Although some of these principles already had a history in 1970, Marr clearly deserves the credit for their sharp formulation and for a series of attempts leading to a formalization of the problems. His way of dividing the approach into the levels of computational theory, of the algorithm and of the implementation clarified the problems. His creed that human visual processing is modular, and that different types of information, which are encoded in the image can be decoded independently by modules, has been ge…

Analyse des Visuellen Klassifikationssystems Durch Detektionsexperimente

Summary Experiments on recognizing statistically distorted patterns show that the human visual system operates as a linear classifier. The spatial frequency range, within which features are extracted, is determined by the coupling in the area of sharpest vision (2°). The relevant features for classifying patterns are not produced by isotropic filtering

On the function of cell systems in area 18. Part I

In addition to the asymmetry of the spatial coupling and of the specific temporal combination of excitation and inhibition, the non-linearity is very pronounced in area 18. Taking the sequence of a linear operation and a stationary nonlinear characteristic as a model, the experimental findings can be systematized and a cell classification specified which departs from the customary ones. The hypercomplex cell system probably originates in recurrent inhibition and leads to differentiation of the patterns along their contour line. Problems of cell classification and of the type of parallelism in the visual cortex are discussed.

VISOCAR: an autonomous industrial transport vehicle guided by visual navigation

The authors describe a vision system, called VISOCAR, for mobile robot guidance in industrial environments. VISOCAR is an optically navigating AGV (automatically guided vehicle) that, owing to its local intelligence, can travel automatically in its natural environment, does not need any dedicated floor installations, and does not impose any restrictions on the route network or factory environment. It can navigate accurately on its track and integrate multisensor information to enhance functional redundancy and system reliability. It is shown that the navigation task can be broken down into a hierarchy of goals, which can be attained by functionally independent modules. The system architectu…

Schema theory: A new approach?

New balloon catheter for prolonged percutaneous transluminal coronary angioplasty and bypass flow in occluded vessels.

A new balloon catheter was developed for continuous perfusion of coronary arteries during angioplasty (CPC catheter). Steerable Gruntzig balloon catheters (3.7 mm) with two lumina were formed. The first lumen was used for balloon inflation. Side holes to the second lumen proximally and distally to the balloon were created for coronary perfusion even during inflation phase. At a perfusion pressure of 120 mmHg, a flow rate of 63 +/- 3 ml/min with 0.9% saline and 43 +/- 1 ml/min with plasma expander were measured. In experiments on five dogs, dilation time until appearance of signs of ischemia could be prolonged in three of five dogs from 30 to 40 s, 120 to 203 s, and 180 to 420 s comparing co…

Abstract: Gewebeklassifikation in der NMR-Tomographie

Die NMR-Tomographie zeichnet sich gegenuber anderen bildgebenden Verfahren (z.B. Ultraschall) dadurch aus, das die Modellgleichungen fur die verschiedenen Experimente die gemessenen Werte relativ gut beschreiben. Hierdurch lassen sich auch die Merkmale eindeutig im Parameterraum definieren, so das eine intuitive Bestimmung entfallt.