Differential Associative Training Enhances Olfactory Acuity in Drosophila melanogaster
Differential Associative Training Enhances Olfactory Acuity in Drosophila melanogaster
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DOI：
10.1523/jneurosci.2598-13.2014
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发表时间：
2014-01-29
影响因子：
5.3
通讯作者：
Fiala, Andre
中科院分区：
文献类型：
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作者：
Barth, Jonas;Dipt, Shubham;Fiala, Andre
训练可以提高区分相似的、易混淆的刺激的能力，包括气味。增强行为表达辨别力(即感官敏锐度)的一种可能性依赖于差异联想学习，在此过程中，动物被迫检测相似刺激之间的差异。果蝇是分析气味处理和嗅觉学习的神经机制的关键模式生物。然而，苍蝇通过差分联想学习增强对相似气味的精细区分的能力尚未得到详细分析。我们使用化学上相似的气味进行了联合条件反射实验，我们发现这些气味可以唤起苍蝇触角叶中重叠的神经元活动，以及蘑菇体叶中高度相关的活动。我们比较了动物在接受两种训练之一后在辨别这些气味方面的表现：要么是绝对条件反射，在这两种训练中只强化了一种气味，要么是差异条件反射，在这种训练中，一种气味被强化，另一种气味明显不强化。首先，我们证明了在选择情境中，差异条件作用减少了相似气味的行为泛化。其次，我们证明这种后天的嗅觉增强依赖于条件性兴奋和条件性抑制。第三，触角叶的抑制性局部中间神经元被证明是对两种相似气味的行为精细区分所必需的。第四，差异化但不是绝对的训练会导致蘑菇体中气味表征的去关联。总而言之，具有相似气味的差异训练最终会导致两个相似刺激之间的行为表现出的对比度增强，从而促进细微的辨别。
Training can improve the ability to discriminate between similar, confusable stimuli, including odors. One possibility of enhancing behaviorally expressed discrimination (i.e., sensory acuity) relies on differential associative learning, during which animals are forced to detect the differences between similar stimuli. Drosophila represents a key model organism for analyzing neuronal mechanisms underlying both odor processing and olfactory learning. However, the ability of flies to enhance fine discrimination between similar odors through differential associative learning has not been analyzed in detail. We performed associative conditioning experiments using chemically similar odorants that we show to evoke overlapping neuronal activity in the fly's antennal lobes and highly correlated activity in mushroom body lobes. We compared the animals' performance in discriminating between these odors after subjecting them to one of two types of training: either absolute conditioning, in which only one odor is reinforced, or differential conditioning, in which one odor is reinforced and a second odor is explicitly not reinforced. First, we show that differential conditioning decreases behavioral generalization of similar odorants in a choice situation. Second, we demonstrate that this learned enhancement in olfactory acuity relies on both conditioned excitation and conditioned inhibition. Third, inhibitory local interneurons in the antennal lobes are shown to be required for behavioral fine discrimination between the two similar odors. Fourth, differential, but not absolute, training causes decorrelation of odor representations in the mushroom body. In conclusion, differential training with similar odors ultimately induces a behaviorally expressed contrast enhancement between the two similar stimuli that facilitates fine discrimination.