CERVO Brain Research Center, Quebec City, QC, G1J 2G3, Canada.
Departement of Psychiatry and Neuroscience, Université Laval, Quebec City, QC, G1K 7P4, Canada.
Sci Rep. 2018 Jun 20;8(1):9385. doi: 10.1038/s41598-018-27692-8.
The adult mouse olfactory bulb is continuously supplied with new neurons that mostly differentiate into granule cells (GCs). Different subtypes of adult-born GCs have been identified, but their maturational profiles and their roles in bulbar network functioning and odor behavior remain elusive. It is also not known whether the same subpopulations of GCs born during early postnatal life (early-born) or during adulthood (adult-born) differ in their morpho-functional properties. Here, we show that adult-born calretinin-expressing (CR) and non-expressing (CR) GCs, as well as early-born CR GCs, display distinct inhibitory inputs but indistinguishable excitatory inputs and similar morphological characteristics. The frequencies of inhibitory post-synaptic currents were lower in early-born and adult-born CR GCs than in adult-born CR neurons. These findings were corroborated by the reduced density of gephyrin puncta on CR GCs. CR GCs displayed a higher level of activation following olfactory tasks based on odor discrimination, as determined by an immediate early gene expression analysis. Pharmacogenetic inhibition of CR GCs diminished the ability of the mice to discriminate complex odor mixtures. Altogether, our results indicate that distinct inhibitory inputs are received by adult-born CR and CR GCs, that early- and adult-born CR neurons have similar morpho-functional properties, and that CR GCs are involved in complex odor discrimination tasks.
成年鼠嗅球持续产生新的神经元，这些神经元主要分化为颗粒细胞（GCs）。已经鉴定出不同亚型的成年产生的 GCs，但它们的成熟特征及其在嗅球网络功能和气味行为中的作用仍然难以捉摸。也不知道在早期出生后（早期出生）或成年期（成年出生）产生的相同 GCs 亚群在形态功能特性上是否存在差异。在这里，我们表明，成年产生的钙结合蛋白表达（CR）和不表达（CR）GCs，以及早期产生的 CR GC，表现出不同的抑制性输入，但兴奋性输入不可区分，并且具有相似的形态特征。抑制性突触后电流的频率在早期和成年产生的 CR GC 中低于成年产生的 CR 神经元。这些发现通过减少 CR GC 上的 Gephyrin 斑点密度得到了证实。通过即时早期基因表达分析，基于气味辨别，CR GC 显示出更高水平的激活。CR GC 的药理学抑制降低了小鼠辨别复杂气味混合物的能力。总的来说，我们的结果表明，成年产生的 CR 和 CR GC 接收不同的抑制性输入，早期和成年产生的 CR 神经元具有相似的形态功能特性，并且 CR GC 参与复杂的气味辨别任务。
