Background/Aims: Olfactory dysfunction can provide valuable insight into early pathophysiological processes of brain disorders. Olfactory processing of chemosensory and odour sensitivity relies on segregating salient odours from background odours cues. Odour-evoked fast oscillations in the olfactory bulb (OB) are hypothesized to be an important index of odour quality coding. The present preclinical work aimed at better understanding connectivity associated with odour coding and behavioural odour discrimination. Methods: Network oscillations and functional connectivity (FC) were measured in C57BL/6 mice performing the olfactory associative odour learning (OL) test, using multichannel local field potential recordings in key olfactory networks. Cholinergic modulation of odour processing was investigated using the muscarinic antagonist scopolamine. Results: At the behavioural level, olfactory memory, which refers to the acquisition and recollection of a reference odour by reduced exploration time, was observed in animals that correctly learned the task. Significant decrease in mean investigation and retrieval time of the associated odour-food reward was observed between trials. At the network level, the associated odour during sniffing behaviour was associated with enhanced coherence in the β and γ frequency oscillations across the olfactory pathway, with marked changes observed between the OB and anterior piriform cortex (PC). The enhanced phase-amplitude cross-frequency coupling in the OB and the weak coupling index in the hippocampal CA1 suggests a role of the OB network in olfaction encoding and processing. Scopolamine impaired behavioural and FC underlying recall and retrieval of the associated odour. Conclusion: The results suggest that the acquisition and formation of odour reference memory rely primarily on FC at the OB-PC network and confirm the role of muscarinic receptors in olfactory retrieval processing.
Neuropsychobiology

中文翻译：

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小鼠气味检索处理：嗅球-梨状网络中振荡耦合的胆碱能调节

背景/目的：嗅觉功能障碍可以为大脑疾病的早期病理生理过程提供有价值的见解。化学感觉和气味敏感性的嗅觉处理依赖于将显着气味与背景气味线索分开。嗅球 (OB) 中由气味引起的快速振荡被假设为气味质量编码的重要指标。目前的临床前工作旨在更好地了解与气味编码和行为气味辨别相关的连通性。方法：使用关键嗅觉网络中的多通道局部场电位记录，在执行嗅觉联想气味学习 (OL) 测试的 C57BL/6 小鼠中测量网络振荡和功能连接性 (FC)。使用毒蕈碱拮抗剂东莨菪碱研究了气味处理的胆碱能调节。结果：在行为水平上，在正确学习任务的动物中观察到嗅觉记忆，即通过减少探索时间来获取和回忆参考气味。在试验之间观察到相关气味食物奖励的平均调查和检索时间显着减少。在网络层面，嗅探行为期间相关的气味与嗅觉通路中β和γ频率振荡的一致性增强有关，在OB和梨状前皮质（PC）之间观察到显着变化。OB 中增强的相位幅度交叉频率耦合和海马 CA1 中的弱耦合指数表明 OB 网络在嗅觉编码和处理中的作用。结论：结果表明气味参考记忆的获得和形成主要依赖于OB-PC网络中的FC，证实了毒蕈碱受体在嗅觉检索过程中的作用。
神经心理生物学