Precise subcellular input retinotopy and its computational consequences in an identified visual interneuron.
The Lobula Giant Movement Detector (LGMD) is a higher-order visual interneuron of Orthopteran insects that responds preferentially to objects approaching on a collision course. It receives excitatory input from an entire visual hemifield that anatomical evidence suggests is retinotopic. We show that this excitatory projection activates calcium-permeable nicotinic acetylcholine receptors. In vivo calcium imaging reveals that the excitatory projection preserves retinotopy down to the level of a single ommatidium. Examining the impact of retinotopy on the LGMD's computational properties, we show that sublinear synaptic summation can explain orientation preference in this cell. Exploring retinotopy's impact on directional selectivity leads us to infer that the excitatory input to the LGMD is intrinsically directionally selective. Our results show that precise retinotopy has implications for the dendritic integration of visual information in a single neuron.
Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA. perons@janelia.hhmi.org
Simon P
SP
Peron
Peter W
PW
Jones
Fabrizio
F
Gabbiani
D000109:Acetylcholine / Q000494:pharmacology; D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism; D003198:Computer Simulation; D003712:Dendrites / Q000378:metabolism / Q000502:physiology*; D005260:Female; D006110:Grasshoppers; D007395:Interneurons / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D008959:Models, Neurological; D009039:Motion Perception / Q000502:physiology*; D009415:Nerve Net; D009433:Neural Inhibition; D010775:Photic Stimulation / Q000379:methods; D017729:Presynaptic Terminals / Q000502:physiology; D011978:Receptors, Nicotinic / Q000502:physiology; D013028:Space Perception / Q000502:physiology; D014794:Visual Fields; D014795:Visual Pathways / Q000187:drug effects / Q000502:physiology*
D011978:Receptors, Nicotinic; D000109:Acetylcholine; D002118:Calcium