Odor encoding by signals in the olfactory bulb
Odor encoding by signals in the olfactory bulb
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DOI：
10.1152/jn.00449.2022
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发表时间：
2023-02-01
影响因子：
2.5
通讯作者：
Rolls，Edmund T.
中科院分区：
文献类型：
--
作者：
Verhagen，Justus V.;Baker，Keeley L.;Rolls，Edmund T.
要了解嗅觉系统的运作，必须知道信息是如何在嗅球中编码的。我们应用香农信息理论的方法来解决这个问题，与信号从多达57肾小球同时光学成像从突触前输入肾小球在小鼠背侧（dOB）和侧（IOB）嗅球，响应于6个示范纯化学气味。我们发现，首先，这些信号从肾小球到一组气味的调谐非常广泛，平均稀疏度为0.83，平均信号相关性为0.64。第二，这两个因素都导致了即使是几十个肾小球的群体的反应也只能获得很低的信息，33个肾小球的平均信息只有1.35比特，而完美编码这六种气味所需的信息则为2.58比特。第三，虽然有相当大的兴趣，在时间编码的刺激，包括气味身份的可能性，在突触前肾小球反应的时间方面的信息量是低的（平均0.11位），重要的是，是冗余的，相对于从利率的信息。第四，来自同时记录的肾小球的信息非常逐渐地和非线性地渐近线，表明肾小球没有独立的反应。第五，从人口的信息变得相当迅速，在100毫秒的嗅觉发作，和肾小球反应的峰值是在200毫秒。第六，从IOB的信息是不加性的DOB。新&值得注意的是，我们报告广泛的调谐和低气味的信息，可在整个肾小球的侧球和背球人口。尽管反应潜伏期可以显著预测刺激身份，但这包含非常少的信息，并且没有一个信息不与单独基于速率编码的信息冗余。最后，根据反应最早阶段的重要作用（“首要”）这一新兴概念，我们报告说，每次吸入后信息都会非常迅速地增加。
To understand the operation of the olfactory system, it is essential to know how information is encoded in the olfactory bulb. We applied Shannon information theoretic methods to address this, with signals from up to 57 glomeruli simultaneously optically imaged from presynaptic inputs in glomeruli in the mouse dorsal (dOB) and lateral (lOB) olfactory bulb, in response to six exemplar pure chemical odors. We discovered that, first, the tuning of these signals from glomeruli to a set of odors is remarkably broad, with a mean sparseness of 0.83 and a mean signal correlation of 0.64. Second, both of these factors contribute to the low information that is available from the responses of even populations of many tens of glomeruli, which was only 1.35 bits across 33 glomeruli on average, compared with the 2.58 bits required to perfectly encode these six odors. Third, although there is considerable interest in the possibility of temporal encoding of stimulus including odor identity, the amount of information in the temporal aspects of the presynaptic glomerular responses was low (mean 0.11 bits) and, importantly, was redundant with respect to the information available from the rates. Fourth, the information from simultaneously recorded glomeruli asymptotes very gradually and nonlinearly, showing that glomeruli do not have independent responses. Fifth, the information from a population became available quite rapidly, within 100 ms of sniff onset, and the peak of the glomerular response was at 200 ms. Sixth, the information from the lOB was not additive with that of the dOB.NEW & NOTEWORTHYWe report broad tuning and low odor information available across the lateral and dorsal bulb populations of glomeruli. Even though response latencies can be significantly predictive of stimulus identity, such contained very little information and none that was not redundant with information based on rate coding alone. Last, in line with the emerging notion of the important role of earliest stages of responses (“primacy”), we report a very rapid rise in information after each inhalation.