Claridge-Chang Adam, Roorda Robert D, Vrontou Eleftheria, Sjulson Lucas, Li Haiyan, Hirsh Jay, Miesenböck Gero
Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK.
Cell. 2009 Oct 16;139(2):405-15. doi: 10.1016/j.cell.2009.08.034.
Dopaminergic neurons are thought to drive learning by signaling changes in the expectations of salient events, such as rewards or punishments. Olfactory conditioning in Drosophila requires direct dopamine action on intrinsic mushroom body neurons, the likely storage sites of olfactory memories. Neither the cellular sources of the conditioning dopamine nor its precise postsynaptic targets are known. By optically controlling genetically circumscribed subsets of dopaminergic neurons in the behaving fly, we have mapped the origin of aversive reinforcement signals to the PPL1 cluster of 12 dopaminergic cells. PPL1 projections target restricted domains in the vertical lobes and heel of the mushroom body. Artificially evoked activity in a small number of identifiable cells thus suffices for programming behaviorally meaningful memories. The delineation of core reinforcement circuitry is an essential first step in dissecting the neural mechanisms that compute and represent valuations, store associations, and guide actions.
多巴胺能神经元被认为通过发出诸如奖励或惩罚等显著事件预期变化的信号来驱动学习。果蝇的嗅觉条件作用需要多巴胺直接作用于内在的蘑菇体神经元，而蘑菇体神经元可能是嗅觉记忆的存储位点。目前尚不清楚条件性多巴胺的细胞来源及其精确的突触后靶点。通过光学控制行为果蝇中基因限定的多巴胺能神经元亚群，我们已将厌恶强化信号的起源定位到由12个多巴胺能细胞组成的PPL1簇。PPL1投射靶向蘑菇体垂直叶和根部的受限区域。因此，少数可识别细胞中人工诱发的活动足以编程具有行为意义的记忆。剖析核心强化回路是剖析计算和表征价值、存储关联以及指导行动的神经机制的重要第一步。
