Precise and fuzzy coding by olfactory sensory neurons
Precise and fuzzy coding by olfactory sensory neurons
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DOI：
10.1523/jneurosci.1955-08.2008
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发表时间：
2008-09-24
影响因子：
5.3
通讯作者：
Cobb, Matthew
中科院分区：
文献类型：
--
作者：
Hoare, Derek J.;McCrohan, Catherine R.;Cobb, Matthew
从外周到达大脑的嗅觉信号的确切性质及其再现性基本上仍然未知。在大多数生物体中，嗅觉感觉神经元（OSN）的绝对数量使得测量整个群体的个体反应变得不可能。我们测量了果蝇幼虫中 OSN 对 10 种脂肪族气味（醇和酯）刺激的个体原位电生理活性。我们研究了对照幼虫（总共 296 个 OSN）和具有单一功能 OSN 的幼虫，使用 Gal4 上游激活剂序列系统创建。大多数 OSN 对给定的气味表现出一致、精确的反应（兴奋或抑制）。一些 OSN 还显示出定性可变的响应（“模糊编码”）。这种强大的变异性是这些神经元的固有特性：它与气味类型、浓度、刺激持续时间、基因型或个体间差异无关，并且在对照幼虫和具有一个和两个功能性 OSN 的幼虫中观察到。我们得出的结论是，在果蝇幼虫中，外周编码将精确编码与模糊随机反应相结合，其中神经元对给定气味的反应表现出质量可变性。我们假设模糊编码发生在其他生物体中，被转化为不同程度的肾小球激活，并形成嗅觉处理第一阶段反应可变性的关键组成部分。
The exact nature of the olfactory signals that arrive in the brain from the periphery, and their reproducibility, remain essentially unknown. In most organisms, the sheer number of olfactory sensory neurons (OSNs) makes it impossible to measure the individual responses of the entire population. We measured the individual in situ electrophysiological activity of OSNs in Drosophila larvae, in response to stimulation with 10 aliphatic odors (alcohols and esters). We studied control larvae (a total of 296 OSNs) and larvae with a single functional OSN, created using the Gal4-upstream activator sequence system. Most OSNs showed consistent, precise responses (either excitation or inhibition) in response to a given odor. Some OSNs also showed qualitatively variable responses ("fuzzy coding"). This robust variability was an intrinsic property of these neurons: it was not attributable to odor type, concentration, stimulus duration, genotype, or interindividual differences, and was seen in control larvae and in larvae with one and two functional OSNs. We conclude that in Drosophila larvae the peripheral code combines precise coding with fuzzy, stochastic responses in which neurons show qualitative variability in their responses to a given odor. We hypothesize that fuzzy coding occurs in other organisms, is translated into differing degrees of activation of the glomeruli, and forms a key component of response variability in the first stages of olfactory processing.