The Functional Organization Of The Compound Eye

A comprehensive portrayal of the behaviour genetics of the fruit fly (Drosophila melanogaster) and the methods used in these studies.

Sciences may be nowadays grouped into three classes, having as their subjects of study respectively Matter, Life and Intelligence. That "Intelligence" may be studied in a quantitative manner is a discovery of our age, not less significant in many ways than the 17th ceiltury realization that celestial phenomena are of one and the same nature as terrestrial and all other physical accidents. As the latter was accomplished through and accompanied by a major revolution in philosophy and method, so is now the scientific investigation of intelligent phenomena - although harely begun - already causing an unprecedented revolution in all our previous conceptions as mind and machine, society and organization. What electronic com puters have already accomplished in disclosing perspectives to sciences and imposing new approached to management is but a negligible change, if compared to those yet in store, which will closely follow the understanding of the many as yet unknown functional principles which make nervous systems act and react the way they do. The study of Neural Networks is the key point in the systematic quantitative investigation of such phenomena. With patience and humility, neuroanatomists and physiologists try to connect structure with function in systems of neurons which are "simple" enough to be studied with the extant techniques, either because of the paucity of their elements or because of the high degree of symmetry these possess (e. g.

This volume is a collection of essays which attempts to summarize the recent progress in the field of photoreceptor and retinal physiology. Reflecting the way in which research is organized, each author reports on the studies performed with the techniques with which he is most familiar: morpholo gical, chemical or physiological. The first chapters describe the structure of visual cells and the histological architecture of the retina. Next comes a summary of the laws governing photochemical reactions and a report on the biochemistry of photopigments. Four articles cover the optical properties of invertebrate eyes and the electrophysiology and the interactions of their photoreceptors. These are followed by a discussion of the properties of vertebrate eyes, including chapters on optics, on the electrical responses of rods and cones and on the functional organization of the retina. The final chapter provides an extensive review of retinal biochemistry and metabolism. Even though the experimental approach differs, all studies are directed toward the solution of two basic problems: transduction in the photoreceptors and orga nization (often called "information processing") in the retina. The central problem of photoreceptor cells is to determine how light produces a response. We know that illumination evokes electrical changes and we have recently learned a great deal about the features of these changes. The evidence indicates however that elaborate processes must be interposed between the ab sorption of photons by the pigment and the production of electric currents through the membrane. These intermediary cvents remain to be unraveled.

The papers published in this Volume are the fruits of a symposium held in Regensburg in April 1987. The meeting was held to com memorate two most significant events in the development of com pound eye research. In chronological order these are firstly, Sigmund Exner's seminal monograph on the physiology of compound eyes of crustaceans and insects, which was first published in Vienna in 1891, and is now shortly to appear for the first time in the English translation [Exner, S. (1989) The Physiology of the Compound Eyes of Insects and Crustaceans. Springer Berlin Heidelberg New York Tokyo]. Secondly, the meeting was also held in honour of Professor Hansjochem Autrum's 80th birthday. Professor Autrum, who is justly acknowledged as one of the pioneers of modern compound eye research, attended the meeting as the guest of honour. In keeping with these historical occasions, it has been our intention in this volume to present a comprehensive collection of short reviews covering the major aspects of compound eye research. Whilst the most up-to-date developments have been included in every field from optics, through photochemistry, phototransduction, integrative processes and behavior, an attempt has also been made to provide a historical perspective.

This book is the only account of what the bee, as an example of an insect, actually detects with its eyes. Bees detect some visual features such as edges and colours, but there is no sign that they reconstruct patterns or put together features to form objects. Bees detect motion but have no perception of what it is that moves, and certainly they do not recognize "things" by their shapes. Yet they clearly see well enough to fly and find food with a minute brain. Bee vision is therefore relevant to the construction of simple artificial visual systems, for example for mobile robots. The surprising conclusion is that bee vision is adapted to the recognition of places, not things. In this volume, Adrian Horridge also sets out the curious and contentious history of how bee vision came to be understood, with an account of a century of neglect of old experimental results, errors of interpretation, sharp disagreements, and failures of the scientific method. The design of the experiments and the methods of making inferences from observations are also critically examined, with the conclusion that scientists are often hesitant, imperfect and misleading, ignore the work of others, and fail to consider alternative explanations. The erratic path to understanding makes interesting reading for anyone with an analytical mind who thinks about the methods of science or the engineering of seeing machines.