Zhou Ping, Liu Penglai, Zhang Ying, Wang Dejuan, Li Anan
Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China.
Front Cell Neurosci. 2022 Jul 27;16:911439. doi: 10.3389/fncel.2022.911439. eCollection 2022.
Modulation of neural circuits is essential for flexible sensory perception and decision-making in a changing environment. Cholinergic and GABAergic projections to the olfactory system from the horizontal limb of the diagonal band of Broca (HDB) in the basal forebrain are crucial for odor detection and olfactory learning. Although studies have demonstrated that HDB neurons respond during olfactory learning, how cholinergic and GABAergic neurons differ in their response dynamics and roles in olfactory learning remains unclear. In this study, we examined the response profiles of these two subpopulations of neurons during passive odor exposure and associative olfactory learning. We show that the excitatory responses in both cholinergic and GABAergic neurons tended to habituate during repeated passive odor exposure. However, while these habituated responses were also observed in GABAergic neurons during a go-go task, there was no such habituation in cholinergic neurons. Moreover, the responses to S+ and S- trials diverged in cholinergic neurons once mice learned a go/no-go task. Furthermore, the chemogenetic inactivation of cholinergic neurons in the HDB impaired odor discrimination. Together, these findings suggest that cholinergic neurons in the HDB reflect attention to positive reinforcement and may regulate odor discrimination top-down inputs to the olfactory system.
神经回路的调节对于在不断变化的环境中进行灵活的感官感知和决策至关重要。从基底前脑的布罗卡斜带水平支（HDB）向嗅觉系统发出的胆碱能和GABA能投射对于气味检测和嗅觉学习至关重要。尽管研究表明HDB神经元在嗅觉学习过程中会做出反应，但胆碱能和GABA能神经元在反应动力学以及在嗅觉学习中的作用如何不同仍不清楚。在本研究中，我们检查了这两类神经元亚群在被动气味暴露和联想性嗅觉学习过程中的反应情况。我们发现，在重复的被动气味暴露过程中，胆碱能和GABA能神经元的兴奋性反应都趋于习惯化。然而，虽然在“执行-执行”任务期间，GABA能神经元中也观察到了这些习惯化反应，但胆碱能神经元中却没有这种习惯化现象。此外，一旦小鼠学会了“执行/不执行”任务，胆碱能神经元对S+和S-试验的反应就会出现差异。此外，HDB中胆碱能神经元的化学遗传学失活会损害气味辨别能力。总之，这些发现表明，HDB中的胆碱能神经元反映了对正强化的关注，并可能从自上而下调节输入到嗅觉系统的气味辨别。
