Division of Biology, Department of Earth System Science, Fukuoka University Fukuoka, Japan.
Front Syst Neurosci. 2012 Jul 25;6:55. doi: 10.3389/fnsys.2012.00055. eCollection 2012.
In animals, odor qualities are represented as both spatial activity patterns of glomeruli and temporal patterns of synchronized oscillatory signals in the primary olfactory centers. By optical imaging of a voltage-sensitive dye (VSD) and intracellular recording from secondary olfactory interneurons, we examined possible neural correlates of the spatial and temporal odor representations in the primary olfactory center, the antennal lobe (AL), of the cockroach Periplaneta americana. Voltage-sensitive dye imaging revealed that all used odorants induced odor-specific temporal patterns of depolarizing potentials in specific combinations of anterior glomeruli of the AL. The depolarizing potentials evoked by different odorants were temporally synchronized across glomeruli and were termed "synchronized potentials." These observations suggest that odor qualities are represented by spatio-temporal activity patterns of the synchronized potentials across glomeruli. We also performed intracellular recordings and stainings from secondary olfactory interneurons, namely projection neurons and local interneurons. We analyzed the temporal structures of enanthic acid-induced action potentials of secondary olfactory interneurons using simultaneous paired intracellular recording from two given neurons. Our results indicated that the multiple local interneurons synchronously fired in response to the olfactory stimulus. In addition, all stained enanthic acid-responsive projection neurons exhibited dendritic arborizations within the glomeruli where the synchronized potentials were evoked. Since multiple local interneurons are known to synapse to a projection neuron in each glomerulus in the cockroach AL, converging inputs from local interneurons to the projection neurons appear to contribute the odorant specific spatio-temporal activity patterns of the synchronized potentials.
在动物中，气味质量表现为嗅球的空间活动模式和初级嗅觉中枢中同步振荡信号的时间模式。通过电压敏感染料（VSD）的光学成像和二级嗅觉中间神经元的细胞内记录，我们研究了美国蟑螂 Periplaneta americana 的初级嗅觉中枢——触角叶（AL）中空间和时间气味表示的可能神经相关性。电压敏感染料成像显示，所有使用的气味剂都在 AL 的前嗅球的特定组合中诱导了特定的去极化电位的时间模式。不同气味剂诱发的去极化电位在嗅球之间是时间同步的，被称为“同步电位”。这些观察结果表明，气味质量是由嗅球之间同步电位的时空活动模式来表示的。我们还从二级嗅觉中间神经元（即投射神经元和局部中间神经元）进行了细胞内记录和染色。我们使用来自两个给定神经元的同时配对细胞内记录分析了乙二酸诱导的二级嗅觉中间神经元动作电位的时间结构。我们的结果表明，多个局部中间神经元响应嗅觉刺激同步放电。此外，所有染色的乙二酸反应性投射神经元都在诱发同步电位的嗅球内表现出树突分支。由于在蟑螂 AL 的每个嗅球中已知有多个局部中间神经元与投射神经元形成突触，因此来自局部中间神经元的会聚输入似乎有助于同步电位的特定气味特定时空活动模式。
