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Neuron. 2015 Jan 7;85(1):116-130. doi: 10.1016/j.neuron.2014.11.023. Epub 2014 Dec 18.

Delayed coupling to feedback inhibition during a critical period for the integration of adult-born granule cells.

Author information

1
Laboratory of Neuronal Plasticity, Leloir Institute-CONICET, Av. Patricias Argentinas 435, Buenos Aires, C1405BWE, Argentina.
2
Laboratory of Developmental Neurobiology, Leloir Institute-CONICET, Av. Patricias Argentinas 435, Buenos Aires, C1405BWE, Argentina.
3
Laboratory of Neuronal Plasticity, Leloir Institute-CONICET, Av. Patricias Argentinas 435, Buenos Aires, C1405BWE, Argentina. Electronic address: aschinder@leloir.org.ar.

Abstract

Developing granule cells (GCs) of the adult dentate gyrus undergo a critical period of enhanced activity and synaptic plasticity before becoming mature. The impact of developing GCs on the activity of preexisting dentate circuits remains unknown. Here we combine optogenetics, acute slice electrophysiology, and in vivo chemogenetics to activate GCs at different stages of maturation to study the recruitment of local target networks. We show that immature (4-week-old) GCs can efficiently drive distal CA3 targets but poorly activate proximal interneurons responsible for feedback inhibition (FBI). As new GCs transition toward maturity, they reliably recruit GABAergic feedback loops that restrict spiking of neighbor GCs, a mechanism that would promote sparse coding. Such inhibitory loop impinges only weakly in new cohorts of young GCs. A computational model reveals that the delayed coupling of new GCs to FBI could be crucial to achieve a fine-grain representation of novel inputs in the dentate gyrus.

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PMID:
25533485
PMCID:
PMC4329739
DOI:
10.1016/j.neuron.2014.11.023
[Indexed for MEDLINE]
Free PMC Article

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