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SUMMARY:Re-evaluation of learned behaviour\, changing memory - on the fly 
 - Dr Johannes Felsenberg - Centre for Neural Circuits and Behaviour\, Wadd
 ell Lab\, University of Oxford
DTSTART:20190429T120000Z
DTEND:20190429T130000Z
UID:TALK122965@talks.cam.ac.uk
CONTACT:Lorraine Coulson
DESCRIPTION:Animals have to constantly reassess the reliability of learned
  information to optimize their behaviour.  When acquired knowledge turns o
 ut to be inaccurate the underlying memory needs to be re-evaluated.  Some 
 of the basic principles of these memory update processes seem to be conser
 ved from insects to mammals.\n\nWe have started to identify the neural ope
 rations underpinning re-evaluation of memory in Drosophila.  A lack of acc
 uracy of prediction during the retrieval of olfactory memory can either le
 ad to a cycle of memory destabilisation and re-stabilisation\, an update p
 rocess called reconsolidation\, or direct new learning of an opposing memo
 ry\, a phenomenon know as extinction.  Each process involves specific part
 s of the dopaminergic circuitry innervating the flies' memory cenre\, the 
 mushroom body.  During reconsolidiation\, the re-stabilization of the memo
 ry requires activity of a specific set of mushroom body output neurons\, w
 hich sequentially recruit distinct groups of dopaminergic neurons.  In mem
 ory extinction a learned odour that proves an unreliable predictor has its
  associated valence nullified by establishing a new opposing memory.  Base
 d on the involvement of the respective dopaminergic system\, we proposed t
 hat the omission of reward is learned as punishment\, whereas the absence 
 of expected punishment functions as reward.  In vivo imaging reveals the c
 o-existence of the two memory traces\, the original memory and a parallel 
 extinction memory.  Guided by light and ultrastructural anatomy we uncover
 ed a mechanism of how these two memory traces are integrated to guide beha
 viour.  Together\, these data establish that recurrent connectivity betwee
 n valence-coding output neurons and dopaminergic neurons support error dri
 ven memory re-evaluation.
LOCATION:Kenneth Craik Room\, Craik Marshall Building\, Downing Site\, Cam
 bridge
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