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VERSION:2.0
PRODID:-//Memento EPFL//
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SUMMARY:"Functionally heterogeneous synapses shape cell-wide plasticity of
  visual cortex neurons in vivo"
DTSTART:20190514T150000
DTEND:20190514T160000
DTSTAMP:20260428T060516Z
UID:6864acecabc9268e2c64a2c1d01c752386c52c4ec9839afa6f22bc12
CATEGORIES:Conferences - Seminars
DESCRIPTION:Sami El-Boustani\, PhD\nNeuronal circuits in the developing an
 d mature brain are subject to dramatic changes driven by sensory inputs or
  motor learning\, causing individual cells to modify their responses to in
 dividual inputs while maintaining a relatively stable level of overall act
 ivity. Cell-wide homeostatic plasticity was initially reported as a global
  mechanism for stabilizing the output firing rate of a cell by uniformly s
 caling up or down the effective strength of all its synapses. More recent 
 experimental evidence in vitro has suggested the existence of local homeos
 tatic mechanisms acting at the level of dendritic stretches or even at sin
 gle synapses that would potentially confer rich functional compartmentaliz
 ation within the dendritic tree. However\, the existence and nature of loc
 al compensatory plasticity in vivo and its implications for the coherent r
 eorganization of single cell responses remains unexplored. In particular\,
  it has been pointed out that the joint action of Hebbian and homeostatic 
 plasticity in synaptic ensembles could impede the formation of new functio
 ns by cancelling each other. Here we have used visual-optogenetic pairing 
 to demonstrate that induction of receptive field plasticity in single visu
 al cortex neurons of awake mice alters identified synapses on neuronal den
 drites. Such plasticity potentiates specific synapses and depresses others
  within short stretches of the same dendrite\, consistent with functionall
 y heterogeneous local sets of synapses that convey diverse receptive field
  inputs to a neuron. Crucially\, depressed spines lie in close proximity t
 o potentiated spines\, indicating coordinated Hebbian and heterosynaptic l
 ong-term depression in vivo that involves neighbouring synapses. AMPA rece
 ptors are trafficked into potentiated spines and removed from depressed sp
 ines via targeted expression of the immediate early gene product Arc in th
 e latter spines. Locally coordinated potentiation and depression of spines
 \, mediated by Arc\, also underlies functional changes in eye-specific res
 ponses of visual cortex neurons following monocular deprivation and recove
 ry. The spatially local distribution of depressed spines around potentiate
 d spines\, in conjunction with functionally intermixed synaptic inputs to 
 dendrites\, demonstrates a powerful new mechanism that organizes cell-wide
  plasticity with local dendritic interactions.
LOCATION:Campus Biotech Geneva https://plan.epfl.ch/?room==B1%206%20272.04
 3
STATUS:CONFIRMED
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