Motion detection in flies: Parametric control over ON-OFF pathways

Abstract
Summary Microscopic illumination of two neighbouring photoreceptor cells within a single ommatidium induces a strong sequence-dependent response in a directionally selective, motion-sensitive neuron. The response is characterized by a strong facilitation in the preferred direction and a weaker inhibition in the reverse direction. The data suggest that for each direction of apparent movement the signal from an ON-OFF pathway is released into the neuron via a parametric control mechanism which is activated by an adjacent channel.