Supporting data for "Learning improves decoding of odor identity with phase-referenced oscillations in the olfactory bulb"

Local field potential oscillations reflect temporally coordinated neuronal ensembles coupling distant brain regions, gating processing windows, and providing a reference for spike timing-based codes. In phase amplitude coupling (PAC), the amplitude of the envelope of a faster oscillation is larger within a phase window of a slower carrier wave. Here, we characterized PAC, and the related theta phase-referenced high gamma and beta power (PRP), in the olfactory bulb of mice learning to discriminate odorants. PAC changes throughout learning, and odorant-elicited changes in PRP increase for rewarded and decrease for unrewarded odorants. Contextual odorant identity (is the odorant rewarded?) can be decoded from peak PRP in animals proficient in odorant discrimination, but not in naïve mice. As the animal learns to discriminate the odorants the dimensionality of PRP decreases. Therefore, modulation of phase-referenced chunking of information in the course of learning plays a role in early sensory processing in olfaction.

局部场电位（Local Field Potential, LFP）振荡既能够反映协调远距离脑区活动的时间同步神经元集群，也可实现加工窗口的门控，并为基于锋电位时序的编码提供参照基准。在相位振幅耦合（Phase Amplitude Coupling, PAC）现象中，快振荡包络的振幅在慢载波的特定相位窗口内会显著增大。本研究针对学习辨别气味的小鼠嗅球内的PAC，以及与之相关的θ相位参考高γ和β功率（theta phase-referenced high gamma and beta power, PRP）展开了特征表征分析。研究发现，PAC在整个学习过程中会发生动态变化，且气味诱发的PRP变化呈现出奖赏性气味增强、非奖赏性气味减弱的特征。对于熟练掌握气味辨别能力的动物而言，可通过其峰值PRP解码出气味的情境属性（即该气味是否被奖赏），但未经历训练的小鼠则无法实现该解码。随着动物逐步掌握气味辨别任务，PRP的维度会逐渐降低。综上，学习过程中基于相位的信息分块调控，在嗅觉的早期感觉加工中发挥着关键作用。