Neurophysiology of Behaviour Laboratory, Francis Crick Institute, London, NW1 1AT, UK.
Department of Neuroscience, Physiology & Pharmacology, University College London, London, UK.
eNeuro. 2018 Dec 26;5(5). doi: 10.1523/ENEURO.0148-18.2018. eCollection 2018 Sep-Oct.
In awake mice, sniffing behavior is subject to complex contextual modulation. It has been hypothesized that variance in inhalation dynamics alters odor concentration profiles in the naris despite a constant environmental concentration. Using whole-cell recordings in the olfactory bulb of awake mice, we directly demonstrate that rapid sniffing mimics the effect of odor concentration increase at the level of both mitral and tufted cell (MTC) firing rate responses and temporal responses. Paradoxically, we find that mice are capable of discriminating fine concentration differences within short timescales despite highly variable sniffing behavior. One way that the olfactory system could differentiate between a change in sniffing and a change in concentration would be to receive information about the inhalation parameters in parallel with information about the odor. We find that the sniff-driven activity of MTCs without odor input is informative of the kind of inhalation that just occurred, allowing rapid detection of a change in inhalation. Thus, a possible reason for sniff modulation of the early olfactory system may be to directly inform downstream centers of nasal flow dynamics, so that an inference can be made about environmental concentration independent of sniff variance.
在清醒的老鼠中,嗅探行为受到复杂的上下文调制。有人假设,尽管环境浓度保持不变,但吸入动力学的变化会改变鼻腔中的气味浓度分布。通过对清醒老鼠嗅球的全细胞记录,我们直接证明,快速嗅探模拟了气味浓度增加对嗅球放电率和时间响应的影响。矛盾的是,我们发现尽管嗅探行为变化很大,但老鼠能够在短时间内区分细微的浓度差异。嗅觉系统区分嗅探变化和浓度变化的一种方法是,与气味信息并行接收关于吸入参数的信息。我们发现,没有气味输入的嗅球细胞的嗅探驱动活动可以提供刚刚发生的吸入类型的信息,从而可以快速检测到吸入的变化。因此,早期嗅觉系统的嗅探调制的一个可能原因是直接向下游中心提供鼻腔气流动力学的信息,以便可以根据嗅探变化以外的因素推断环境浓度。