Yang Chu-Huai, Shih Meng-Fu Maxwell, Chang Ching-Ching, Chiang Meng-Hsuan, Shih Hsiang-Wen, Tsai Ya-Lun, Chiang Ann-Shyn, Fu Tsai-Feng, Wu Chia-Lin
Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
Institute of Biotechnology, National Tsing Hua University, Hsinchu, Taiwan.
PLoS Genet. 2016 May 19;12(5):e1006061. doi: 10.1371/journal.pgen.1006061. eCollection 2016 May.
Associative olfactory memory in Drosophila has two components called labile anesthesia-sensitive memory and consolidated anesthesia-resistant memory (ARM). Mushroom body (MB) is a brain region critical for the olfactory memory and comprised of 2000 neurons that can be classified into αβ, α'β', and γ neurons. Previously we demonstrated that two parallel pathways mediated ARM consolidation: the serotonergic dorsal paired medial (DPM)-αβ neurons and the octopaminergic anterior paired lateral (APL)-α'β' neurons. This finding prompted us to ask how this composite ARM is retrieved. Here, we showed that blocking the output of αβ neurons and that of α'β' neurons each impaired ARM retrieval, and blocking both simultaneously had an additive effect. Knockdown of radish and octβ2R in αβ and α'β' neurons, respectively, impaired ARM. A combinatorial assay of radish mutant background rsh1 and neurotransmission blockade confirmed that ARM retrieved from α'β' neuron output is independent of radish. We identified MBON-β2β'2a and MBON-β'2mp as the MB output neurons downstream of αβ and α'β' neurons, respectively, whose glutamatergic transmissions also additively contribute to ARM retrieval. Finally, we showed that α'β' neurons could be functionally subdivided into α'β'm neurons required for ARM retrieval, and α'β'ap neurons required for ARM consolidation. Our work demonstrated that two parallel neural pathways mediating ARM consolidation in Drosophila MB additively contribute to ARM expression during retrieval.
果蝇的联想嗅觉记忆有两个组成部分,分别称为不稳定的麻醉敏感记忆和巩固的麻醉抗性记忆(ARM)。蘑菇体(MB)是对嗅觉记忆至关重要的脑区,由2000个神经元组成,可分为αβ、α'β'和γ神经元。此前我们证明了两条平行通路介导ARM巩固:血清素能的背侧配对内侧(DPM)-αβ神经元和章鱼胺能的前侧配对外侧(APL)-α'β'神经元。这一发现促使我们探究这种复合的ARM是如何被提取的。在这里,我们表明阻断αβ神经元和α'β'神经元的输出均会损害ARM提取,同时阻断两者具有累加效应。分别在αβ和α'β'神经元中敲低萝卜(radish)和章鱼胺β2受体(octβ2R)会损害ARM。对萝卜突变体背景rsh1和神经传递阻断的组合分析证实,从α'β'神经元输出中提取的ARM与萝卜无关。我们分别鉴定出MBON-β2β'2a和MBON-β'2mp为αβ和α'β'神经元下游的MB输出神经元,它们的谷氨酸能传递也对ARM提取有累加作用。最后,我们表明α'β'神经元在功能上可细分为ARM提取所需的α'β'm神经元和ARM巩固所需的α'β'ap神经元。我们的研究表明,果蝇蘑菇体中两条介导ARM巩固的平行神经通路在提取过程中对ARM表达有累加作用。