title: Visualizing retinotopic half-wave rectified input to the motion detection circuitry of Drosophila.
abstract: In the visual system of Drosophila, photoreceptors R1-R6 relay achromatic brightness information to five parallel pathways. Two of them, the lamina monopolar cells L1 and L2, represent the major input lines to the motion detection circuitry. We devised a new method for optical recording of visually evoked changes in intracellular Ca2+ in neurons using targeted expression of a genetically encoded Ca2+ indicator. Ca2+ in single terminals of L2 neurons in the medulla carried no information about the direction of motion. However, we found that brightness decrements (light-OFF) induced a strong increase in intracellular Ca2+ but brightness increments (light-ON) induced only small changes, suggesting that half-wave rectification of the input signal occurs. Thus, L2 predominantly transmits brightness decrements to downstream circuits that then compute the direction of image motion.
authors.affiliation: Max Planck Institute of Neurobiology, Martinsried, Germany. reiff@neuro.mpg.de
authors.forename: Dierk F
authors.initials: DF
authors.lastname: Reiff
authors.forename: Johannes
authors.initials: J
authors.lastname: Plett
authors.forename: Marco
authors.initials: M
authors.lastname: Mank
authors.forename: Oliver
authors.initials: O
authors.lastname: Griesbeck
authors.forename: Alexander
authors.initials: A
authors.lastname: Borst
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D004330:Drosophila; D005074:Evoked Potentials, Visual / Q000502:physiology; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000166:cytology / Q000502:physiology*; D014795:Visual Pathways / Q000166:cytology / Q000502:physiology*
chemical_list: D002118:Calcium