Friedrich R W, Korsching S I
Max-Planck-Institut für Entwicklungsbiologie, Abteilung Physikalische Biologie, D-72076 Tübingen, Germany.
J Neurosci. 1998 Dec 1;18(23):9977-88. doi: 10.1523/JNEUROSCI.18-23-09977.1998.
Odor information is first represented in the brain by patterns of input activity across the glomeruli of the olfactory bulb (OB). To examine how odorants are represented at this stage of olfactory processing, we labeled anterogradely the axons of olfactory receptor neurons with the voltage-sensitive dye Di8-ANEPPQ in zebrafish. The activity induced by diverse natural odorants in afferent axons and across the array of glomeruli was then recorded optically. The results show that certain subregions of the OB are preferentially activated by defined chemical odorant classes. Within these subregions, "ordinary" odorants (amino acids, bile acids, and nucleotides) induce overlapping activity patterns involving multiple glomeruli, indicating that they are represented by combinatorial activity patterns. In contrast, two putative pheromone components (prostaglandin F2alpha and 17alpha, 20beta-dihydroxy-4-pregnene-3-one-20-sulfate) each induce a single focus of activity, at least one of which comes from a single, highly specific and sensitive glomerulus. These results indicate that the OB is organized into functional subregions processing classes of odorants. Furthermore, they suggest that individual odorants can be represented by "combinatorial" or "noncombinatorial" (focal) activity patterns and that the latter may serve to process odorants triggering distinct responses such as that of pheromones.
气味信息首先在大脑中由嗅球（OB）各嗅小球的输入活动模式来表征。为了研究在嗅觉处理的这一阶段气味剂是如何被表征的，我们用电压敏感染料Di8 - ANEPPQ对斑马鱼嗅觉受体神经元的轴突进行顺行标记。然后通过光学记录不同天然气味剂在传入轴突和整个嗅小球阵列中诱导产生的活动。结果表明，嗅球的某些亚区域优先被特定的化学气味剂类别激活。在这些亚区域内，“普通”气味剂（氨基酸、胆汁酸和核苷酸）诱导涉及多个嗅小球的重叠活动模式，这表明它们由组合活动模式来表征。相比之下，两种假定的信息素成分（前列腺素F2α和17α, 20β - 二羟基 - 4 - 孕烯 - 3 - 酮 - 20 - 硫酸盐）各自诱导一个单一的活动焦点，其中至少一个来自单个高度特异且敏感的嗅小球。这些结果表明，嗅球被组织成处理不同类别气味剂的功能亚区域。此外，它们表明单个气味剂可以由“组合”或“非组合”（焦点）活动模式来表征，并且后者可能用于处理引发不同反应（如信息素反应）的气味剂。
