Barbarossa Iole Tomassini, Muroni Patrizia, Setzu Maria D, Angioy Anna Maria
Department of Experimental Biology, Section of General Physiology, University of Cagliari, Monserrato-Cagliari 09042, Italy.
Chem Senses. 2007 Jul;32(6):535-41. doi: 10.1093/chemse/bjm022. Epub 2007 May 7.
Olfactory sensory stimulation induces a fast-phase arrest response (FPA-R) of the blowfly heart activity that has been described as a sensitive tool for testing insect reactivity to odor perception. We analyzed FPA-R occurrence to repeated olfactory stimulation with low and high 1-hexanol concentrations that are behaviorally attractant and repellent, respectively, in the blowfly. FPA-R occurrence diminished and ceased with repeated presentations of low and medium odor concentrations, according to dynamics inversely related to odor doses. On the other hand, repeated stimulation with higher odor concentrations induced persistent FPA-Rs. Sensory input amplitude to repeated presentations of singly tested odor concentrations did not change throughout stimulation sessions. A spontaneous restoration of FPA-R to olfactory stimulation was recorded 30 min after cessation of FPA-R to a previous olfactory stimulation session. However, a prompt restoration of FPA-R to olfactory stimulation after cessation of FPA-R was obtained following mechano-taste stimulation of labellar sensilla. Our findings show that the FPA-R habituates to olfactory sensory stimulation with low and medium odor concentrations according to dynamics inversely related to odor intensities. On the other hand, the FPA-R does not habituate to higher odor concentrations. Therefore, flies learn to disregard nonaversive odor information, but they cannot ignore iterative detection of a repellent volatile.
嗅觉感官刺激会诱发家蝇心脏活动的快速相位停止反应（FPA-R），该反应已被描述为测试昆虫对气味感知反应性的一种灵敏工具。我们分析了分别以低浓度和高浓度1-己醇进行重复嗅觉刺激时FPA-R的出现情况，低浓度和高浓度1-己醇在家蝇行为上分别具有吸引和驱避作用。根据与气味剂量呈反比的动态变化，随着低浓度和中等浓度气味的重复呈现，FPA-R的出现减少并停止。另一方面，用较高浓度气味进行重复刺激会诱发持续的FPA-R。在整个刺激过程中，对单一测试气味浓度的重复呈现的感觉输入幅度没有变化。在对前一次嗅觉刺激停止FPA-R 30分钟后，记录到FPA-R对嗅觉刺激的自发恢复。然而，在对唇叶感器进行机械味觉刺激后，FPA-R停止后能迅速恢复对嗅觉刺激的反应。我们的研究结果表明，根据与气味强度呈反比的动态变化，FPA-R会对低浓度和中等浓度气味的嗅觉感官刺激产生习惯化。另一方面，FPA-R不会对较高浓度气味产生习惯化。因此，家蝇学会忽略无厌恶作用的气味信息，但它们无法忽视对驱避性挥发物的反复检测。
