Olfactory memories are intensity specific in larval Drosophila
Olfactory memories are intensity specific in larval Drosophila
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DOI：
10.1242/jeb.082222
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发表时间：
2013-05-01
影响因子：
2.8
通讯作者：
Gerber, Bertram
中科院分区：
文献类型：
--
作者：
Mishra, Dushyant;Chen, Yi-Chun;Gerber, Bertram
学习可以依赖于刺激的质量、刺激的强度或两者的结合。在嗅觉方面，气味质量的编码通常被认为是沿嗅觉通路的组合，并且关于气味质量的短期联想记忆痕迹形成有工作假设。然而，气味强度是如何编码的，以及嗅觉记忆痕迹是否包含了学习到的气味强度的信息，这些都不太清楚。利用果蝇幼虫的气味-糖联想条件作用，我们首先描述了四种不同气味（n-乙酸戊酯、3-辛醇、1-辛醇-3-醇和苯甲醛）在气味强度中的可学习性的剂量效应曲线。然后，我们选择气味强度，使幼虫在中等气味强度下训练，但在训练的中等气味强度下或分别在更高或更低的气味强度下测试保留率。我们观察到所有四种气味的训练强度的保留特异性。这增加了对嗅觉短期记忆痕迹“内容”的丰富程度的认识，即使在像果蝇幼虫这样简单的系统中也是如此，并定义了对联想嗅觉记忆痕迹形成的计算模型的要求。我们提出了两种有可能适应强度学习的电路结构，并讨论了它们如何在昆虫大脑中实现。
Learning can rely on stimulus quality, stimulus intensity, or a combination of these. Regarding olfaction, the coding of odour quality is often proposed to be combinatorial along the olfactory pathway, and working hypotheses are available concerning short-term associative memory trace formation of odour quality. However, it is less clear how odour intensity is coded, and whether olfactory memory traces include information about the intensity of the learnt odour. Using odour-sugar associative conditioning in larval Drosophila, we first describe the dose-effect curves of learnability across odour intensities for four different odours (n-amyl acetate, 3-octanol, 1-octen-3-ol and benzaldehyde). We then chose odour intensities such that larvae were trained at an intermediate odour intensity, but were tested for retention with either that trained intermediate odour intensity, or with respectively higher or lower intensities. We observed a specificity of retention for the trained intensity for all four odours used. This adds to the appreciation of the richness in 'content' of olfactory short-term memory traces, even in a system as simple as larval Drosophila, and to define the demands on computational models of associative olfactory memory trace formation. We suggest two kinds of circuit architecture that have the potential to accommodate intensity learning, and discuss how they may be implemented in the insect brain.