Responses of visual interneurons in the fly optic lobe during stimulation by motion in depth

Summary A high-order wide-field neuron in the optic lobe of the fly,Phormia terraenovae (Calliphoridae), has been investigated by stimulation with simple or multiple black stripes on a white background moving sinusoidally towards and away from the head. The variation in spike frequency in correlation with the optical stimulation provides evidence that the unit detects angular velocity as well as more complex features of the stimulus. It responds preferentially to movement towards the head. Spike frequency turned out to be a two-valued function of relative angular velocity across the eye. A simple formula predicts the highly reliable responses to visual stimuli in different parts of the visual field.The author wants to thank Professor G. A. Horridge for his valuable support and clarifying discussions and to Dr. M. Srinivasan for his comments. The project has been supported by grants from the Swedish Council for Natural Science Research.