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SUMMARY:BMI SEMINAR // Learning-related plasticity of dendritic inhibition
  in neocortical layer 1
DTSTART:20180516T121500
DTEND:20180516T131500
DTSTAMP:20260506T205337Z
UID:7c90f55c48a6638aa76116726da3c0cf34a1b5c3f236505af9f13b86
CATEGORIES:Conferences - Seminars
DESCRIPTION:Johannes Letzkus\, Neocortical Circuits Lab\, Max Planck Insti
 tute for Brain Research\, Frankfurt\, Germany\nTransient breaks in the exc
 itation-inhibition ratio termed disinhibition have been shown to contribut
 e to both memory acquisition and expression in a number of recent studies.
  However\, whether disinhibition occurs throughout the somatodendritic dom
 ain of pyramidal neurons\, or alternatively represents a redistribution of
  inhibition within the neuron remains little understood. To address this q
 uestion\, here we focus on neocortical layer 1\, a key location for proces
 sing of top-down information implicated in learning. Using a novel genetic
  marker for a subpopulation of layer 1 interneurons (Ndnf) in combination 
 with in vivo 2-photon calcium imaging\, in vitro electrophysiology\, viral
  tracing and optogenetics\, we find that Ndnf positive layer 1 interneuron
 s in auditory cortex provide inhibition widely to interneurons in layer 1 
 and lower layers\, as well as the distal dendrites of pyramidal neurons. T
 hese connections recruit a strong component of GabaB receptor signalling\,
  and thereby control the initiation of dendritic spikes in pyramidal cells
 . To address whether Ndnf positive layer 1 interneurons show learning-rela
 ted plasticity\, we combined in vivo calcium imaging with a form of cortex
 -dependent auditory fear learning. These experiments reveal that sensory r
 esponses of Ndnf positive layer 1 interneurons are potentiated in response
  to learning in proportionality to the strength of the memory. In contrast
 \, a second source of dendritic inhibition derived from somatostatin-posit
 ive Martinotti cells remains unchanged after learning. Together\, these re
 sults indicate that\, in addition to disinhibition\, memory retrieval is a
 ssociated with an increase in a specialized from of dendritic inhibition.\
 n 
LOCATION:SV 1717 https://plan.epfl.ch/?room==SV%201717
STATUS:CONFIRMED
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