University of Konstanz, Department of Biology-Neurobiology, 78457 Konstanz, Germany.
J Neurosci. 2013 Apr 3;33(14):6060-9. doi: 10.1523/JNEUROSCI.5838-12.2013.
Airborne odorants rarely occur as pure, isolated stimuli. In a natural environment, odorants that intermingle from multiple sources create mixtures in which the onset and offset of odor components are asynchronous. Odor mixtures are known to elicit interactions in both behavioral and physiological responses, changing the perceptive quality of mixtures compared with the components. However, relevant odors need to be segregated from a distractive background. Honeybees (Apis mellifera) can use stimulus onset asynchrony of as little as 6 ms to segregate learned odor components within a mixture. Using in vivo calcium imaging of projection neurons in the honeybee, we studied neuronal mechanisms of odor-background segregation based on stimulus onset asynchrony in the antennal lobe. We found that asynchronous mixtures elicit response patterns that are different from their synchronous counterpart: the responses to asynchronous mixtures contain more information about the constituent components. With longer onset shifts, more features of the components were present in the mixture response patterns. Moreover, we found that the processing of asynchronous mixtures activated more inhibitory interactions than the processing of synchronous mixtures. This study provides evidence of neuronal mechanisms that underlie odor-object segregation on a timescale much faster than found for mammals.
空气中的气味很少以纯的、孤立的刺激形式出现。在自然环境中，来自多个来源的气味混合会产生混合物，其中气味成分的起始和结束是不同步的。已知气味混合物在行为和生理反应中会引起相互作用，与混合物的成分相比，改变了混合物的感知质量。然而，相关的气味需要与分散注意力的背景分离。蜜蜂（Apis mellifera）可以利用刺激起始时间差小至 6 毫秒来分离混合物中的学习气味成分。利用蜜蜂触角叶中投射神经元的活体钙成像，我们基于触角叶中的刺激起始时间差研究了基于刺激起始时间差的气味-背景分离的神经元机制。我们发现，异步混合物引起的反应模式与同步混合物不同：异步混合物的反应包含更多关于组成成分的信息。随着起始时间差的增加，混合物反应模式中出现了更多的成分特征。此外，我们发现异步混合物的处理比同步混合物的处理激活了更多的抑制相互作用。这项研究提供了证据，证明了在比哺乳动物更快的时间尺度上，气味物体分离的神经元机制。
