Max Planck Institut für Neurobiologie, Martinsried, Germany.
PLoS Genet. 2012;8(7):e1002768. doi: 10.1371/journal.pgen.1002768. Epub 2012 Jul 12.
Animals acquire predictive values of sensory stimuli through reinforcement. In the brain of Drosophila melanogaster, activation of two types of dopamine neurons in the PAM and PPL1 clusters has been shown to induce aversive odor memory. Here, we identified the third cell type and characterized aversive memories induced by these dopamine neurons. These three dopamine pathways all project to the mushroom body but terminate in the spatially segregated subdomains. To understand the functional difference of these dopamine pathways in electric shock reinforcement, we blocked each one of them during memory acquisition. We found that all three pathways partially contribute to electric shock memory. Notably, the memories mediated by these neurons differed in temporal stability. Furthermore, combinatorial activation of two of these pathways revealed significant interaction of individual memory components rather than their simple summation. These results cast light on a cellular mechanism by which a noxious event induces different dopamine signals to a single brain structure to synthesize an aversive memory.
动物通过强化来获得感觉刺激的预测值。在黑腹果蝇的大脑中，已经证明 PAM 和 PPL1 簇中的两种类型的多巴胺神经元的激活会诱导厌恶气味记忆。在这里，我们确定了第三种细胞类型，并对这些多巴胺神经元诱导的厌恶记忆进行了特征描述。这三种多巴胺通路都投射到蘑菇体，但在空间上分离的子域中终止。为了了解这些多巴胺通路在电击强化中的功能差异，我们在记忆获取过程中阻断了它们中的每一条。我们发现这三种途径都对电击记忆有一定的贡献。值得注意的是，这些神经元介导的记忆在时间稳定性上存在差异。此外，这两种途径的组合激活揭示了单个记忆成分之间存在显著的相互作用，而不是它们的简单总和。这些结果揭示了一种细胞机制，即有害事件会向单个大脑结构诱导不同的多巴胺信号，从而合成厌恶记忆。
