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SUMMARY:EM-based connectomics of motion detection pathways in the lobula o
 f Drosophila melanogaster - Dr Kazunori Shinomiya\, Department of Psycholo
 gy and Neuroscience\, Life Sciences Centre\, Dalhousie University\, Halifa
 x NS\, Canada.
DTSTART:20140905T110000Z
DTEND:20140905T120000Z
UID:TALK54097@talks.cam.ac.uk
CONTACT:32335
DESCRIPTION:In the fly’s visual system\, two types of neurons\, T4 and T
 5 cells\, are identified to relay motion information to the lobula plate t
 angential cells (LPTCs). In a recent study\, two cells have been identifie
 d as interneurons in the medulla that mediate signals from the L1 cell\, a
  lamina neuron\, to the T4 cell\, suggesting their function as an elementa
 ry motion detector (EMD).\nUsing serial-section transmission electron micr
 oscopy (ssTEM) approach\, I investigated the downstream of the L2 cell\, a
  counterpart of the L1 cell\, to identify the synaptic connectivity of the
  neurons within the lobula. Among the postsynaptic elements of the L2\, Tm
 1\, 2 and 4 were identified as input neurons to the T5 cell. The Tm9 cell\
 , which receives direct input from the L3 cell\, was found to unexpectedly
  feed into the T5 as well. This result shows that the signals from the L2 
 and L3 pathways are integrated at the T5 cell\, being consistent with the 
 report that L2 and L3 are coordinately employed in moving dark-edge detect
 ion. The presynaptic terminals of Tm1\, 2 and 9 cells altogether form a co
 lumnar structure within the lobula\, while a T5 cell extends postsynaptic 
 arbors to a wider area\, receiving multicolumnar input from the Tm cells. 
 Synaptic inputs from Tm1 and Tm2\, and Tm2 and Tm9\, turned out to be spat
 ially segregated. Also\, transcript profiling of T5 cells revealed that th
 ey express two different types of cholinoceptors\, supporting the fact tha
 t both Tm2 and Tm9\, the two major inputs to T5\, are cholinergic. These f
 eatures of the Tm and T5 cells provide a candidate substrate for an EMD ci
 rcuit for dark-edge detection by computing small-field motion signals.\n\n
 Host and contact person: Liria Masuda-Nakagawa (lm546@cam.ac.uk)\nPlease l
 et Liria know if you would like to meet Kazunori after the seminar.
LOCATION:Part II lecture room\, Department of Genetics
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