Information processing by dynamic neuronal circuits subjected to adult neurogenesis.

LUCAS A MONGIAT

Buzios

Simposio; IV International Symposium Frontiers in Neuroscience; 2017

D'OR Research Institute

p { margin-bottom: 0.25cm; line-height: 120%; }Theaddition of new neurons into developed brains is the most complexgrade of neural plasticity known. In the roden dentate gyrus,adult-born granule cells (ab-GCs) undergo a critical period ofenhanced activity and synaptic plasticity before becoming mature. Theimpact of developing ab-GCs on the activity of preexisting dentatecircuits remains unknown. Here we combine optogenetics, acute sliceelectrophysiology, and in vivo chemogenetics to activate GCs atdifferent stages of maturation to study the recruitment of differenttarget networks. We show that immature (four-week-old) ab-GCs canefficiently drive distal CA3 targets, but poorly activate proximalinterneurons responsible for local feedback inhibition (FBI). As newGCs transition towards maturity, they reliably recruit GABAergicfeedback loops to restrict the spiking of neighbor GCs, a mechanismthat would promote sparse coding. Such inhibitory loop impinges onlyweakly in new cohorts of young GCs. In this way, the delayed couplingof new GCs to FBI could be crucial to achieve a fine-grainrepresentation of novel inputs in the dentate gyrus.