title: Functional specialization of parallel motion detection circuits in the fly.
abstract: In the fly Drosophila melanogaster, photoreceptor input to motion vision is split into two parallel pathways as represented by first-order interneurons L1 and L2 (Rister et al., 2007; Joesch et al., 2010). However, how these pathways are functionally specialized remains controversial. One study (Eichner et al., 2011) proposed that the L1-pathway evaluates only sequences of brightness increments (ON-ON), while the L2-pathway processes exclusively brightness decrements (OFF-OFF). Another study (Clark et al., 2011) proposed that each of the two pathways evaluates both ON-ON and OFF-OFF sequences. To decide between these alternatives, we recorded from motion-sensitive neurons in flies in which the output from either L1 or L2 was genetically blocked. We found that blocking L1 abolishes ON-ON responses but leaves OFF-OFF responses intact. The opposite was true, when the output from L2 was blocked. We conclude that the L1 and L2 pathways are functionally specialized to detect ON-ON and OFF-OFF sequences, respectively.
authors: Max Planck Institute of Neurobiology, 82152 Martinsried, Germany.
authors: Maximilian
authors: M
authors: Joesch
authors: Franz
authors: F
authors: Weber
authors: Hubert
authors: H
authors: Eichner
authors: Alexander
authors: A
authors: Borst
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D004331:Drosophila melanogaster / Q000502:physiology*; D005260:Female; D008959:Models, Neurological; D009039:Motion Perception / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*