UMR1272, PISC, Institut National de la Recherche Agronomique--Université Pierre et Marie Curie, Versailles, France.
PLoS One. 2011;6(10):e26443. doi: 10.1371/journal.pone.0026443. Epub 2011 Oct 18.
In nature the aerial trace of pheromone used by male moths to find a female appears as a train of discontinuous pulses separated by gaps among a complex odorant background constituted of plant volatiles. We investigated the effect of such background odor on behavior and coding of temporal parameters of pheromone pulse trains in the pheromone olfactory receptor neurons of Spodoptera littoralis. Effects of linalool background were tested by measuring walking behavior towards a source of pheromone. While velocity and orientation index did drop when linalool was turned on, both parameters recovered back to pre-background values after 40 s with linalool still present. Photo-ionization detector was used to characterize pulse delivery by our stimulator. The photo-ionization detector signal reached 71% of maximum amplitude at 50 ms pulses and followed the stimulus period at repetition rates up to 10 pulses/s. However, at high pulse rates the concentration of the odorant did not return to base level during inter-pulse intervals. Linalool decreased the intensity and shortened the response of receptor neurons to pulses. High contrast (>10 dB) in firing rate between pulses and inter-pulse intervals was observed for 1 and 4 pulses/s, both with and without background. Significantly more neurons followed the 4 pulses/s pattern when delivered over linalool; at the same time the information content was preserved almost to the control values. Rapid recovery of behavior shows that change of perceived intensity is more important than absolute stimulus intensity. While decreasing the response intensity, background odor preserved the temporal parameters of the specific signal.
在自然界中，雄蛾用来寻找雌蛾的信息素的气载轨迹表现为一连串不连续的脉冲，这些脉冲之间隔着由植物挥发物构成的复杂气味背景中的间隙。我们研究了这种背景气味对鳞翅目昆虫触角嗅觉神经元中信息素脉冲串的行为和时间参数编码的影响。通过测量对信息素源的行走行为来测试芳樟醇背景的影响。虽然当芳樟醇打开时，速度和方向指数确实下降，但在芳樟醇仍然存在的情况下，这两个参数在 40 秒后都恢复到背景前的值。光离子化探测器用于描述我们刺激器的脉冲传递。光离子化探测器信号在 50ms 脉冲时达到最大幅度的 71%，并在重复率高达 10 脉冲/s 的情况下跟随刺激周期。然而，在高脉冲率下，在脉冲之间的间隔期间，气味的浓度不会回到基础水平。芳樟醇降低了强度，并缩短了受体神经元对脉冲的反应。在有和没有背景的情况下，1 和 4 脉冲/s 时都观察到脉冲和脉冲之间的间隔之间的放电率存在高对比度（>10dB）。在芳樟醇上传递时，更多的神经元遵循 4 脉冲/s 的模式；同时，信息含量几乎保持在对照值。行为的快速恢复表明，感知强度的变化比绝对刺激强度更为重要。虽然背景气味降低了响应强度，但它保留了特定信号的时间参数。
