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SUMMARY:Neural circuits underlying visually guided behaviors in zebrafish 
 - Michael Orger\, Department of Molecular and Cellular Biology\, Harvard U
 niversity
DTSTART:20090716T110000Z
DTEND:20090716T120000Z
UID:TALK18997@talks.cam.ac.uk
CONTACT:Gregory Jefferis
DESCRIPTION:We use the zebrafish optomotor response as a model for underst
 anding the neural basis of visually guided behaviors. We have created a ne
 w behavioral assay to identify visual stimuli that specifically drive bas
 ic motor patterns in zebrafish. These stimuli evoked consistent patterns 
 of neural activity in the neurons projecting to the spinal cord\, which we
  could map throughout the entire population using in vivo two-photon calci
 um imaging. We found that stimuli that drive distinct behaviors activated 
 distinct subsets of projection neurons\, consisting\, in some cases\, of j
 ust a few cells. This stands in contrast to the distributed activation see
 n for more complex behaviors. Furthermore\, targeted cell by cell ablation
 s of the neurons associated with evoked turns abolished the corresponding 
 behavioral response. For a more systematic characterization of responses t
 hroughout the zebrafish brain\, we have made transgenic lines with pan-neu
 ronal expression of genetically-encoded calcium indicators. Fish expressin
 g the indicator GCaMP2 show responses with high signal to noise allowing s
 timulus tuning of neurons to be measured reliably\, even with a single pre
 sentation. This opens up the possibility of functionally mapping a complet
 e vertebrate brain with cellular precision and provides a framework for id
 entifying the complete circuit underlying a vertebrate behaviur.
LOCATION:MRC LMB: Neurobiology Division Seminar Room (Level 2)
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