Centre for Neural Circuits and Behaviour, The University of Oxford, Tinsley Building, Mansfield Road, Oxford OX1 3SR, UK.
Drosophila Connectomics, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
Cell. 2018 Oct 18;175(3):709-722.e15. doi: 10.1016/j.cell.2018.08.021. Epub 2018 Sep 20.
Accurately predicting an outcome requires that animals learn supporting and conflicting evidence from sequential experience. In mammals and invertebrates, learned fear responses can be suppressed by experiencing predictive cues without punishment, a process called memory extinction. Here, we show that extinction of aversive memories in Drosophila requires specific dopaminergic neurons, which indicate that omission of punishment is remembered as a positive experience. Functional imaging revealed co-existence of intracellular calcium traces in different places in the mushroom body output neuron network for both the original aversive memory and a new appetitive extinction memory. Light and ultrastructural anatomy are consistent with parallel competing memories being combined within mushroom body output neurons that direct avoidance. Indeed, extinction-evoked plasticity in a pair of these neurons neutralizes the potentiated odor response imposed in the network by aversive learning. Therefore, flies track the accuracy of learned expectations by accumulating and integrating memories of conflicting events.
准确预测结果需要动物从连续的经验中学习支持和矛盾的证据。在哺乳动物和无脊椎动物中，经历无惩罚的预测线索可以抑制习得的恐惧反应，这个过程被称为记忆消除。在这里，我们表明，果蝇的厌恶记忆的消除需要特定的多巴胺能神经元，这表明省略惩罚被记住是一种积极的体验。功能成像显示，在蘑菇体输出神经元网络中，原始厌恶记忆和新的奖赏性消退记忆的细胞内钙痕迹共存。光和超微结构解剖学与在蘑菇体输出神经元内平行竞争记忆的结合一致，这些神经元指导回避。事实上，这对神经元中的一个神经元的消退诱发的可塑性，消除了网络中由厌恶学习引起的增强的气味反应。因此，苍蝇通过积累和整合冲突事件的记忆来跟踪学习期望的准确性。
