Towards an Ecology of Motion Vision

Abstract

Natural motion signals, as a working definition, are those that are actually encountered by specific animals in the environment they normally operate in. The need to consider specific animals arises because the motion signals that are processed by a brain depend on the ethological and ecological context. Motion signals are determined by environmental motion, by the type and structure of locomotion of an animal, and by the visual topography of the world the animal operates in. We suggest that it is essential to consider natural motion signals in more detail, since they may reveal constraints that have shaped the evolution of motion detection and information processing mechanisms. The primary focus of this paper is to outline what needs to be considered and what is required to characterize the biologically relevant information content of the visual motion environment of an animal. In particular, we discuss the principal sources of image motion, critically assess the different ways of reconstructing, analysing and modelling natural motion signals, and briefly summarize current attempts to identify coding strategies, matched filters and optimization of neurones involved in processing visual information. We end with a survey of sensory and neural adaptations to show the multiple levels of processing at which motion filters have evolved under the influence of natural motion signals.