The rodent olfactory bulb (OB) is continuously supplied with adult-born cells maturing into GABAergic neurons. Using in vivo ratiometric Ca²⁺ imaging to readout ongoing and sensory-driven activity, we asked whether mature adult-born cells (mABCs) in the glomerular layer of the bulb become functionally identical to resident GABAergic (Res_GABA) neurons. In awake head-restrained mice the two cell populations differed significantly in terms of ongoing spontaneous activity, with 24% of mABCs contributing to a strongly active cell cluster, absent among Res_GABA cells. Odor-evoked responses of mABCs were sparse, less reliable, and had smaller amplitudes compared with Res_GABA cells. The opposite was seen under anesthesia, with response reliability increasing and response size of mABCs becoming larger than that of Res_GABA cells. Furthermore, ongoing activity of mABCs showed increased sensitivity to ketamine/xylazine and was selectively blocked by the antagonist of serotonin receptors methysergide. These functional features of mABCs clearly distinguish them from other OB interneurons.

啮齿动物的嗅球 (OB) 不断提供成熟为 GABA 能神经元的成人出生细胞。使用体内比例 Ca ²⁺成像来读出正在进行的和感觉驱动的活动，我们询问球茎肾小球层中的成熟成体细胞 (mABC) 是否在功能上与常驻 GABA 能 (Res _GABA ) 神经元相同。在清醒的头部约束小鼠中，两种细胞群在持续的自发活动方面存在显着差异，24% 的 mABCs 有助于强烈活跃的细胞簇，而 Res _GABA细胞中不存在。与 Res _GABA相比，mABCs 的气味诱发反应稀疏、可靠性较低且振幅较小细胞。在麻醉下观察到相反的情况，反应可靠性增加并且 mABC 的反应大小变得大于 Res _GABA细胞的反应大小。此外，mABC 的持续活性显示出对氯胺酮/赛拉嗪的敏感性增加，并被血清素受体美西麦角拮抗剂选择性阻断。mABCs 的这些功能特征清楚地将它们与其他 OB 中间神经元区分开来。