title: Temporal statistics of natural image sequences generated by movements with insect flight characteristics.
abstract: Many flying insects, such as flies, wasps and bees, pursue a saccadic flight and gaze strategy. This behavioral strategy is thought to separate the translational and rotational components of self-motion and, thereby, to reduce the computational efforts to extract information about the environment from the retinal image flow. Because of the distinguishing dynamic features of this active flight and gaze strategy of insects, the present study analyzes systematically the spatiotemporal statistics of image sequences generated during saccades and intersaccadic intervals in cluttered natural environments. We show that, in general, rotational movements with saccade-like dynamics elicit fluctuations and overall changes in brightness, contrast and spatial frequency of up to two orders of magnitude larger than translational movements at velocities that are characteristic of insects. Distinct changes in image parameters during translations are only caused by nearby objects. Image analysis based on larger patches in the visual field reveals smaller fluctuations in brightness and spatial frequency composition compared to small patches. The temporal structure and extent of these changes in image parameters define the temporal constraints imposed on signal processing performed by the insect visual system under behavioral conditions in natural environments.
authors.affiliation: Neurobiology & Cognitive Interaction Technology Center of Excellence (CITEC), Bielefeld University, Bielefeld, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Schwegmann
authors.affiliation: Neurobiology & Cognitive Interaction Technology Center of Excellence (CITEC), Bielefeld University, Bielefeld, Germany.
authors.forename: Jens Peter
authors.initials: JP
authors.lastname: Lindemann
authors.affiliation: Neurobiology & Cognitive Interaction Technology Center of Excellence (CITEC), Bielefeld University, Bielefeld, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Egelhaaf
mesh_terms: D000818:Animals; D003198:Computer Simulation; D005426:Flight, Animal / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D007313:Insecta / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D011336:Probability; D012399:Rotation; D013223:Statistics as Topic; D013997:Time Factors; D014794:Visual Fields / Q000502:physiology