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SUMMARY:Hippocampal network dynamics underpinning the emergence and persis
 tence of spatial memories - David Dupret - Department of Pharmacology\, Un
 iversity of Oxford
DTSTART:20140508T150000Z
DTEND:20140508T160000Z
UID:TALK51886@talks.cam.ac.uk
CONTACT:Philipe Mendonca
DESCRIPTION:How do brain dynamics support the emergence of new memories\, 
 and what network mechanisms underlie the strengthening of those that final
 ly persist? These central questions of neuroscience can be addressed in th
 e case of spatial memories by observing and manipulating the activity of t
 he hippocampus\, a circuit that provides the rodent brain with a map-like 
 representation of space. In this talk I will present a series of experimen
 ts where we monitored hippocampal network activity in rodents during the a
 cquisition\, consolidation and recall stages of spatial memory tasks. Firs
 t\, I will show that during goal-directed learning\, when the network is d
 ominated by theta-band (5-12Hz) oscillations\, emerging cell assemblies co
 mpete for expression against previously established ones. This 'flickering
 ' of assemblies is associated with changes in the firing associations of i
 nterneurons to the new pyramidal-cell assemblies. New hippocampal represen
 tations\, however\, will degrade with time unless stabilized by additional
  processes. In another set of experiments we found compelling evidence tha
 t hippocampal sleep reactivation during sharp wave/ripple (150-250Hz) even
 ts can be primed by midbrain dopaminergic afferents active during learning
  to further consolidate newly-encoded spatial representations. Our finding
 s highlight the importance of elaborate neuronal coordination between the 
 hippocampus and related circuits during spatial learning to support both t
 he assignment of behavioural experiences to separate neuronal assemblies a
 nd their selective persistence.
LOCATION:Main Lecture Theatre\, Physiology Building\, Downing Site
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