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SUMMARY:BMI SEMINAR //  Marlene Bartos - Emergence of stable and dynamic m
 emory engrams in the hippocampus
DTSTART:20190220T121500
DTEND:20190220T131500
DTSTAMP:20260501T164730Z
UID:13ab7a7a34f11fdc5730e90f0d6e761e38737dfb7c89c97c4c1bd0a7
CATEGORIES:Conferences - Seminars
DESCRIPTION: Marlene Bartos\, Cellular and Systemic Neuroscience\, Instit
 ute for Physiology I\, University of Freiburg\, Germany\nAbstract: During 
 our daily life\, we depend on memories of past experiences to plan future 
 behaviour. These memories are represented by the activity of specific neur
 onal groups or ‘engrams’. Neuronal engrams are assembled during learni
 ng by synaptic modification\,\nand engram reactivation represents the memo
 rized experience. Engrams of conscious memories are initially stored in th
 e hippocampus for several days and then transferred to cortical areas. In 
 the dentate gyrus of the hippocampus\, granule cells transform\nrich input
 s from the entorhinal cortex into a sparse output\, which is forwarded to 
 the highly interconnected pyramidal cell network in hippocampal area CA3. 
 This process is thought to support pattern\nseparation. CA3 pyramidal neur
 ons project to CA1\, the hippocampal output region. Consistent with the id
 ea of transient memory storage in the hippocampus\, engrams in CA1 and CA2
  do not stabilize over time. Nevertheless\, reactivation of\nengrams in th
 e dentate gyrus can induce recall of artificial memories even after weeks.
  Reconciliation of this apparent paradox will require recordings from dent
 ate gyrus granule cells throughout learning\, which has so far not been pe
 rformed for more than a single day. We used chronic two-photon calcium ima
 ging in head-fixed mice performing a multiple-day spatial memory task in a
  virtual environment to record neuronal activity in all major hippocampal 
 subfields. Pyramidal neurons in CA1–CA3 show precise and highly context-
 specific\, but continuously changing\, representations of the learned spat
 ial sceneries in our behavioural paradigm. In contrast\, granule cells in 
 the dentate gyrus have a spatial code that is stable over many days\, with
  low place- or context-specificity. Our results suggest that synaptic weig
 hts along the hippocampal trisynaptic loop are constantly reassigned to su
 pport the formation of dynamic representations in downstream hippocampal a
 reas based on a stable code provided by the dentate gyrus.\n 
LOCATION:SV 1717 https://plan.epfl.ch/?room==SV%201717
STATUS:CONFIRMED
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