Distinctive Neuronal Networks and Biochemical Pathways for Appetitive and Aversive Memory in Drosophila Larvae
Distinctive Neuronal Networks and Biochemical Pathways for Appetitive and Aversive Memory in Drosophila Larvae
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DOI：
10.1523/jneurosci.1315-08.2009
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发表时间：
2009-01-21
影响因子：
5.3
通讯作者：
Furukubo-Tokunaga, Katsuo
中科院分区：
文献类型：
--
作者：
Honjo, Ken;Furukubo-Tokunaga, Katsuo
条件刺激（CS）和非条件刺激（US）之间的联想强度被认为决定经典条件反射的学习效能。因此，阐明大脑中CS和US之间关联的神经元机制对于理解记忆形成的原理至关重要。果蝇幼虫具有简单的大脑组织，为研究神经回路水平的学习提供了一个有吸引力的模型系统。先前，我们描述了一种以蔗糖作为奖励的幼虫联想学习的单气味范式，并表明幼虫的食欲记忆持续时间超过2小时。在这项工作中，我们描述了在我们的范式中形成的幼虫厌恶嗅觉记忆的行为和遗传特征，并将其稳定性和神经回路与食欲记忆进行了比较。在相同的训练模式下，用奎宁或NaCl形成的幼虫嗅觉记忆是短暂的，在20分钟内就会消失。与食欲记忆一样，在这种模式下产生的幼虫厌恶记忆依赖于完整的cAMP信号，但健忘症的突变和CREB活性的抑制都不会影响其动力学。神经电路分析表明，与食欲记忆一样，厌恶记忆储存在幼虫体神经元的突触前末梢之前。然而，章鱼胺和多巴胺能神经元的突触输出分别是获得食欲记忆和厌恶记忆所需要的，它们在幼虫体和触角叶上表现出不同的神经支配模式。这些结果作为一个整体表明，基因编程的记忆回路可能在联想学习中诱导长期记忆成分的功效方面提供了倾向。
Associative strength between conditioned stimulus (CS) and unconditioned stimulus (US) is thought to determine learning efficacy in classical conditioning. Elucidation of the neuronal mechanism that underlies the association between CS and US in the brain is thus critical to understand the principle of memory formation. With a simple brain organization, the Drosophila larva provides an attractive model system to investigate learning at the neurocircuitry level. Previously, we described a single-odor paradigm for larval associative learning using sucrose as a reward, and showed that larval appetitive memory lasts longer than 2 h. In this work, we describe behavioral and genetic characterization of larval aversive olfactory memory formed in our paradigm, and compare its stability and neurocircuitry with those of appetitive memory. Despite identical training paradigms, larval olfactory memory formed with quinine or NaCl is short-lived to be lost in 20 min. As with appetitive memory, larval aversive memory produced in this paradigm depends on intact cAMP signaling, but neither mutation of amnesiac nor suppression of CREB activity affects its kinetics. Neurocircuitry analyses suggest that aversive memory is stored before the presynaptic termini of the larval mushroom body neurons as is the case with appetitive memory. However, synaptic output of octopaminergic and dopaminergic neurons, which exhibit distinctive innervation patterns on the larval mushroom body and antennal lobe, is differentially required for the acquisition of appetitive and aversive memory, respectively. These results as a whole suggest that the genetically programmed memory circuitries might provide predisposition in the efficacy of inducing longer-lived memory components in associative learning.