Cenier Tristan, Amat Corine, Litaudon Philippe, Garcia Samuel, Lafaye de Micheaux Pierre, Liquet Benoît, Roux Stéphane, Buonviso Nathalie
Neurosciences Sensorielles, Comportement, Cognition, CNRS UMR5020, IFNL, Université Claude Bernard Lyon 1, 69366 Lyon cedex 07, France.
Eur J Neurosci. 2008 Mar;27(6):1432-40. doi: 10.1111/j.1460-9568.2008.06123.x.
A central question in chemical senses is the way that odorant molecules are represented in the brain. To date, many studies, when taken together, suggest that structural features of the molecules are represented through a spatio-temporal pattern of activation in the olfactory bulb (OB), in both glomerular and mitral cell layers. Mitral/tufted cells interact with a large population of inhibitory interneurons resulting in a temporal patterning of bulbar local field potential (LFP) activity. We investigated the possibility that molecular features could determine the temporal pattern of LFP oscillatory activity in the OB. For this purpose, we recorded the LFPs in the OB of urethane-anesthetized, freely breathing rats in response to series of aliphatic odorants varying subtly in carbon-chain length or functional group. In concordance with our previous reports, we found that odors evoked oscillatory activity in the LFP signal in both the beta and gamma frequency bands. Analysis of LFP oscillations revealed that, although molecular features have almost no influence on the intrinsic characteristics of LFP oscillations, they influence the temporal patterning of bulbar oscillations. Alcohol family odors rarely evoke gamma oscillations, whereas ester family odors rather induce oscillatory patterns showing beta/gamma alternation. Moreover, for molecules with the same functional group, the probability of gamma occurrence is correlated to the vapor pressure of the odor. The significance of the relation between odorant features and oscillatory regimes along with their functional relevance are discussed.
化学感官中的一个核心问题是气味分子在大脑中的呈现方式。迄今为止，许多研究综合起来表明，分子的结构特征通过嗅球（OB）中肾小球层和二尖瓣细胞层的时空激活模式来呈现。二尖瓣/簇状细胞与大量抑制性中间神经元相互作用，导致球部局部场电位（LFP）活动的时间模式。我们研究了分子特征是否能够决定OB中LFP振荡活动的时间模式。为此，我们记录了在氨基甲酸乙酯麻醉、自由呼吸的大鼠OB中的LFP，以响应一系列碳链长度或官能团略有不同的脂肪族气味剂。与我们之前的报告一致，我们发现气味在β和γ频段的LFP信号中诱发了振荡活动。对LFP振荡的分析表明，虽然分子特征对LFP振荡的内在特征几乎没有影响，但它们会影响球部振荡的时间模式。醇类气味很少诱发γ振荡，而酯类气味则更容易诱发呈现β/γ交替的振荡模式。此外，对于具有相同官能团的分子，γ出现的概率与气味的蒸气压相关。本文讨论了气味特征与振荡状态之间关系的意义及其功能相关性。
