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SUMMARY:Tracing memory circuits in Drosophila using whole-brain electron m
 icroscopy  - Dr. Davi Bock\, Janelia Research Campus 
DTSTART:20160617T090000Z
DTEND:20160617T100000Z
UID:TALK66361@talks.cam.ac.uk
CONTACT:Robert Jones
DESCRIPTION:Electron microscopy (EM) has sufficient resolution to map neur
 al circuits at the level of individual neurons and the chemical synapses b
 etween them. Ongoing advances in EM imaging hardware and software have per
 mitted increasingly large volumes of neural tissue to be imaged\, using a 
 variety of EM-based methods. We recently developed a second-generation tra
 nsmission EM camera array (TEMCA2)\, capable of acquiring high quality ima
 ges with sustained throughput of ~50 MPix/s at 4x4 nm/pixel\, as well as a
 n Autoloader for hands-free sample exchange\, enabling days to weeks of au
 tomated imaging without manual intervention. We used this infrastructure t
 o image the complete brain of a female adult fruit fly Drosophila melanoga
 ster. The resulting dataset comprises 21 million images occupying 106 TB o
 n disk. We also developed a downstream cluster-backed image processing pip
 eline to stitch\, register\, and intensity correct these images\, enabling
  manual tracing of neuronal connectivity spanning the entire fly brain.\n\
 nWe focused our pilot tracing efforts on the interface between the olfacto
 ry system and the mushroom body\, the site of associative learning in the 
 fly. The mushroom body contains ~2\,000 Kenyon cells (KCs) on each side of
  the brain\, which receive a large olfactory input from the antennal lobe 
 via second-order olfactory projection neurons (PNs). KC dendrites receive 
 input from PNs in the calyx of the mushroom body in what is thought to be 
 a random fashion. KC axons then project anteriorly in a bundle called the 
 pedunculus\, to the lobes of the mushroom body where synaptic modulation u
 nderlying memory formation occurs. We reconstructed ~10% of the KCs in the
  calyx and their presynaptic PN inputs to generate a PN-to-KC connectivity
  graph.\n\nWe find that KCs that fasciculate with one another in the pedun
 culus are much more likely to receive input from a common PN\, and are mor
 e likely to make axo-axonic synapses with one another in the pedunculus. S
 ince KCs with shared PN input are expected to have more correlated spiking
  activity\, the network structure we describe here could result in the poo
 ling of olfactory information between more highly correlated KCs\, prior t
 o the arrival of that information in downstream circuits for associative l
 earning. 
LOCATION:MRC LMB: Klug Seminar Room 2A180
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