Evolution of Biological Image Stabilization

The use of vision to coordinate behavior requires an efficient control design that stabilizes the world on the retina or directs the gaze towards salient features in the surroundings. With a level gaze, visual processing tasks are simplified and behaviorally relevant features from the visual environment can be extracted. No matter how simple or sophisticated the eye design, mechanisms have evolved across phyla to stabilize gaze. In this review, we describe functional similarities in eyes and gaze stabilization reflexes, emphasizing their fundamental role in transforming sensory information into motor commands that support postural and locomotor control. We then focus on gaze stabilization design in flying insects and detail some of the underlying principles. Systems analysis reveals that gaze stabilization often involves several sensory modalities, including vision itself, and makes use of feedback as well as feedforward signals. Independent of phylogenetic distance, the physical interaction between an animal and its natural environment — its available senses and how it moves — appears to shape the adaptation of all aspects of gaze stabilization. Involuntary reflexes are silently stabilizing your eyes on these words without you being aware of them – in their absence, reading would be almost impossible. In this review, Hardcastle and Krapp discuss the general principles of image stabilization in biology and some of the ingenious adaptations that have evolved to support visually guided behavior.