In recent years there has been steadily increasing interest in motor behavior and a growing awareness that a person not only has to know what to do in a particular situation, but also how to do it. The question of how actions are performed is of central concern in the area of motor control. This volume provides an advanced-level treatment of some of the main issues. Experiments concerned with basic processes of motor control typ ically examine very simple movements. At first glance these tasks appear to be far removed from real-world tasks, but it should be kept in mind that they are not studied for their own sake. One of the main reasons for using them is the well-recognized, but sometimes questioned, scientific principle that basic laws may be discovered more easily in simple situations than iIi complex situations. Another reason is that the simple tasks studied constitute building blocks of more complex tasks. For example, some complex skills can be consid ered as consisting of sequences of aimed movements, although, as no one would doubt, knowing everything about these individual movements does not mean knowing everything about, for example, typing. The first two chapters of the present volume focus on behavioral and physiological studies of programming and preparation of move ments. In the first chapter D. Rosenbaum introduces the concept of a motor program that is set up in advance of the overt movement."

During the academic year 1984/85 a study group on "Per- ception and Action" was established at the Center for Inter- disciplinary Research of the University of Bielefeld. Among the various activities of this group was a series of symposia. This volume covers the proceedings of one of the sym- posia, held in October 1984 and entitled "Generation and Modulation of Action Patterns". Bringing together scientists from diverse disciplines in gen- eral is challenging, but also hazardous. Aware of the notori- ous communication problems, it was tried to keep the number of representatives of at least the major areas of Neurobiology and Psychology about equal and to elicit pre- sentations that combine experimental findings with theoret- ical statements on major issues in motor control. Despite the different' viewpoints, concepts, research strategies, and methods as they are reflected in the present volume, there was the general impression among the participants that such a multidisciplinary effort was profitable and one step on the way to the realization of common goals and com- mon conceptual grounds.

Originally published in 1987, this title aimed to present an eclectic and biased account of the status of perception-action relationships in various fields at the time. The chapters can be divided into three sections. The first focuses on motor control, a neglected topic in the past and hence deserving the role of the starting point of this volume. In addition motor control provides a good background to discuss the clear sensory and perceptual effects. However, motor processes are also highly relevant to perception, which was usually less emphasized in the literature at the time. Therefore a special section is devoted to motor processes in perception together with the issue of integrating information from different sources. The book concludes with a section on attention and selection of perceptual information for subsequent action.

Die Herzschrittmachertherapie ziihlt zweifelsohne zu den groBen Fortschritten medizini- scher Erkenntnisse der letzten dreiBig Jahre. Menschen, deren Leben bis auf einige wenige Jahre begrenzt war, bekamen es neu geschenkt. Ihre Lebenserwartung konnte nachhaltig verliingert, ihre Lebensqualitiit entscheidend verbessert werden. Die Schritt- macherentwieklung ist aber nieht stehengeblieben. Gerade zur Verbesserung der Lebens- qualitiit konnten in der Entwicklung der letzten Jahre groBe Fortschritte erzielt werden. Das urspriingliche Therapiekonzept war die Verhinderung von Adams-Stokes-Anfiillen, zuniichst beim kompletten AV-Block, aber schon sehr rasch bei allen bradykarden Rhythmusstorungen. Einen wesentliehen Fortschritt stellte hierzu die Einflihrung der Demand-Funktion dar, die eben nur im Bedarfsfall, d. h. beim plotzlichen rhythmogenen Ausfall der Herztiitigkeit, einsetzte, das asystolische Intervall uberbruckte und damit den Adams-Stokes-Anfall verhinderte, ohne sonst die Herztiitigkeit zu storen. Das niich- ste Therapiekonzept betraf die Verbesserung der Hiimodynamik mit dem Ziel, durchAn- hebung der zu langsamen Ruhefrequenz eine Steigerung des Herzminutenvolumens her- beizuflihren. Sehr rasch muBte man jedoch erkennen, daB gerade bei der Hauptgruppe dieser Patienten, d. h. Patienten mit Sinusbradykardie, der gewtinschte Effekt in vielen Fallen ausblieb. Trotz Frequenzanhebung ging es einem Teil dieser Patienten eher schlechter, in manchen Fiillen kam es sogar zu Blutdruckabfall und kollapsiihnlichen Zu- stiinden. Der Begriff "Schrittmachersyndrom" kam auf. Die Losung flir solche Fiille war die Einflihrung der Vorhofstimulation (AAI), die wiederum die Entwieklung geeigneter Vorhofelektroden und Implantationstechniken zur Voraussetzung hatte. Damit lieB sich die Herzfrequenz anheben bei Erhalt der AV-Uberleitung, d. h. physiologischer AV-Syn- chronisation (physiologischer Schrittmacher).