Neuron
Volume 100, Issue 3, 7 November 2018, Pages 684-699.e6
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Article
Learning-Related Plasticity in Dendrite-Targeting Layer 1 Interneurons

https://doi.org/10.1016/j.neuron.2018.09.001Get rights and content
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Highlights

  • NDNF is a selective marker for neocortical layer 1 interneurons

  • NDNF interneurons mediate prolonged inhibition of distal pyramidal neuron dendrites

  • Inhibition from Martinotti cells tightly controls NDNF interneuron responses

  • Dendritic inhibition by NDNF interneurons is highly experience dependent

Summary

A wealth of data has elucidated the mechanisms by which sensory inputs are encoded in the neocortex, but how these processes are regulated by the behavioral relevance of sensory information is less understood. Here, we focus on neocortical layer 1 (L1), a key location for processing of such top-down information. Using Neuron-Derived Neurotrophic Factor (NDNF) as a selective marker of L1 interneurons (INs) and in vivo 2-photon calcium imaging, electrophysiology, viral tracing, optogenetics, and associative memory, we find that L1 NDNF-INs mediate a prolonged form of inhibition in distal pyramidal neuron dendrites that correlates with the strength of the memory trace. Conversely, inhibition from Martinotti cells remains unchanged after conditioning but in turn tightly controls sensory responses in NDNF-INs. These results define a genetically addressable form of dendritic inhibition that is highly experience dependent and indicate that in addition to disinhibition, salient stimuli are encoded at elevated levels of distal dendritic inhibition.

Keywords

neocortical circuits
GABAergic interneurons
layer 1
interneurons
NDNF interneurons
somatostatin interneurons
dendritic inhibition
genetic markers
connectivity
top-down processing
fear learning

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