Diversity and wiring variability of visual local neurons in the Drosophila medulla M6 stratum.
Local neurons in the vertebrate retina are instrumental in transforming visual inputs to extract contrast, motion, and color information and in shaping bipolar-to-ganglion cell transmission to the brain. In Drosophila, UV vision is represented by R7 inner photoreceptor neurons that project to the medulla M6 stratum, with relatively little known of this downstream substrate. Here, using R7 terminals as references, we generated a 3D volume model of the M6 stratum, which revealed a retinotopic map for UV representations. Using this volume model as a common 3D framework, we compiled and analyzed the spatial distributions of more than 200 single M6-specific local neurons (M6-LNs). Based on the segregation of putative dendrites and axons, these local neurons were classified into two families, directional and nondirectional. Neurotransmitter immunostaining suggested a signal routing model in which some visual information is relayed by directional M6-LNs from the anterior to the posterior M6 and all visual information is inhibited by a diverse population of nondirectional M6-LNs covering the entire M6 stratum. Our findings suggest that the Drosophila medulla M6 stratum contains diverse LNs that form repeating functional modules similar to those found in the vertebrate inner plexiform layer.
Institute of Biotechnology and Department of Life Science, National Tsing Hua University, Hsinchu, 30013, Taiwan.
An-Lun
AL
Chin
Chih-Yung
CY
Lin
Tsai-Feng
TF
Fu
Barry J
BJ
Dickson
Ann-Shyn
AS
Chiang
D000818:Animals; D030801:Animals, Genetically Modified; D001931:Brain Mapping; D003198:Computer Simulation; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000378:metabolism; D008526:Medulla Oblongata / Q000166:cytology*; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D010446:Peptide Fragments / Q000378:metabolism; D012160:Retina / Q000502:physiology; D012701:Serotonin / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D050496:Vesicular Glutamate Transport Proteins / Q000378:metabolism; D014785:Vision, Ocular / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D029721:Drosophila Proteins; C557617:GAL4 protein, Drosophila; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D010446:Peptide Fragments; D014157:Transcription Factors; D050496:Vesicular Glutamate Transport Proteins; C086595:influenza hemagglutinin (306-318); D049452:Green Fluorescent Proteins; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D014446:Tyrosine 3-Monooxygenase
UV circuit; retinotopic map; vision