Leibniz Institute for Neurobiology, Department of Genetics, 39118 Magdeburg, Germany.
Institute of Biology, Otto von Guericke University Magdeburg, 39118 Magdeburg, Germany.
J Exp Biol. 2022 Aug 15;225(16). doi: 10.1242/jeb.244565. Epub 2022 Aug 25.
Animals, including humans, form oppositely valenced memories for stimuli that predict the occurrence versus the termination of a reward: appetitive 'reward' memory for stimuli associated with the occurrence of a reward and aversive 'frustration' memory for stimuli that are associated with its termination. We characterized these memories in larval Drosophila melanogaster using a combination of Pavlovian conditioning, optogenetic activation of the dopaminergic central-brain DAN-i1864 neuron, and high-resolution video-tracking. This reveals their dependency on the number of training trials and the duration of DAN-i1864 activation, their temporal stability, and the parameters of locomotion that are modulated during memory expression. Together with previous results on 'punishment' versus 'relief' learning by DAN-f1 neuron activation, this reveals a 2×2 matrix of timing-dependent memory valence for the occurrence/termination of reward/punishment. These findings should aid the understanding and modelling of how brains decipher the predictive, causal structure of events around a target reinforcing occurrence.
动物，包括人类，会形成针对预测奖励出现和终止的刺激物的相反效价记忆：与奖励出现相关的刺激物会产生正向的“奖励”记忆，而与奖励终止相关的刺激物则会产生负向的“挫折”记忆。我们使用巴甫洛夫条件反射、光遗传学激活多巴胺能中央脑 DAN-i1864 神经元以及高分辨率视频追踪的组合，在黑腹果蝇幼虫中对这些记忆进行了表征。这揭示了它们对训练试验次数和 DAN-i1864 激活持续时间的依赖性、它们的时间稳定性以及在记忆表达期间调节的运动参数。结合 DAN-f1 神经元激活的“惩罚”与“缓解”学习的先前结果，这揭示了奖励/惩罚出现/终止的时间依赖记忆效价的 2×2 矩阵。这些发现应该有助于理解和建模大脑如何破译围绕目标强化出现的事件的预测性、因果结构。
