Mapping memory pathways in the Drosophila brain

我们的目标是了解果蝇大脑中记忆形成和存储所需的神经网络。果蝇可以学会在气味和疼痛刺激之间建立联系。我们训练苍蝇的方法是让它们同时接触气味和痛苦的电击。苍蝇学会将气味与疼痛联系起来，然后避开气味。这种关联形成并储存在一种被称为蘑菇体的大脑结构中。将气味信息传递到蘑菇体的神经元通路目前是已知的，但传递休克信息的通路仍不清楚。另外，虽然人们已经知道衰老会导致记忆力下降，但对记忆的形成和保持过程中哪些环节受到衰老的影响还不清楚。去年，我与宫下智之、齐藤实合作，撰写了一篇论文，证明了休克信息是通过神经胶质细胞而不是神经元释放谷氨酸的囊泡传递到蘑菇体的。虽然神经胶质细胞是已知的调节突触活动，这份手稿表明，神经胶质细胞也发挥了直接的作用，在直接传递信息到更高级别的neurons.I也在果蝇遗忘的特点。虽然遗忘是一个主要的研究领域，但人们一直不清楚遗忘是如何发生的。遗忘只是记忆的丧失，还是一个更复杂的过程？我们确定记忆不会在遗忘中丢失。相反，遗忘是由与记忆相关的不确定性增加引起的。

Our goal is to understand the neural networks that are required for memory formation and storage in the Drosophila brain. Drosophila can learn to form associations between odors and painful stimuli. We train flies by exposing them simultaneously to an odor and painful electrical shocks. Flies learn to associate the odor with pain and subsequently avoid the odor. This association is formed and stored in a brain structure known as the mushroom bodies. Neuronal pathways that transmit odor information to the mushroom bodies are currently known, but pathways that transmit shock information is still unelucidated. In addition, although it is known that aging causes decreases in memory, it has been unclear what processes involved in memory formation or retention are affected by aging.This past year, I collaborated with Tomoyuki Miyashita and Minoru Saitoe and helped prepare a manuscript demonstrating that shock information is transmitted to the mushroom bodies through vesicular release of glutamate from glial cells instead of neurons. Although glia are known to modulate synaptic activity, this manuscript demonstrates that glia also play a direct role in directly transmitting information to higher order neurons.I also characterized forgetting in Drosophila. Although forgetting is a major field of study, it has been unclear precisely how forgetting occurs. Is forgetting simply the loss of a memory, or is it a more complex process? We determined that memories are not lost during forgetting. Instead forgetting is caused by an increase in the uncertainty associated with a memory.