Research Centre on Animal Cognition, Centre National de la Recherche Scientifique-Université Paul-Sabatier, Unité Mixte de Recherche 5169, 31062 Toulouse cedex 04, France.
J Neurosci. 2010 May 5;30(18):6461-5. doi: 10.1523/JNEUROSCI.0841-10.2010.
The insect mushroom bodies (MBs) are paired brain centers which, like the mammalian hippocampus, have a prominent function in learning and memory. Despite convergent evidence for their crucial role in the formation and storage of associative memories, little is known about the mechanisms underlying such storage. In mammals and other species, the consolidation of stable memories is accompanied by structural plasticity involving variations in synapse number and/or size. Here, we address the question of whether the formation of olfactory long-term memory (LTM) could be associated with changes in the synaptic architecture of the MB networks. For this, we took advantage of the modular architecture of the honeybee MB neuropil, where synaptic contacts between olfactory input and MB neurons are segregated into discrete units (microglomeruli) which can be easily visualized and counted. We show that the density in microglomeruli increases as a specific olfactory LTM is formed, while the volume of the neuropil remains constant. Such variation is reproducible and is clearly correlated with memory consolidation, as it requires gene transcription. Thus stable structural synaptic rearrangements, including the growth of new synapses, seem to be a common property of insect and mammalian brain networks involved in the storage of stable memory traces.
昆虫的蘑菇体（MBs）是成对的大脑中心，与哺乳动物的海马体一样，在学习和记忆方面具有突出的功能。尽管有证据表明它们在形成和存储联想记忆方面具有至关重要的作用，但对于这种存储的机制知之甚少。在哺乳动物和其他物种中，稳定记忆的巩固伴随着结构可塑性，涉及突触数量和/或大小的变化。在这里，我们探讨了嗅觉长期记忆（LTM）的形成是否与 MB 网络的突触结构变化有关。为此，我们利用了蜜蜂 MB 神经突的模块化结构，其中嗅觉输入和 MB 神经元之间的突触接触被分离成离散的单元（微胶质），可以很容易地可视化和计数。我们表明，当特定的嗅觉 LTM 形成时，微胶质中的密度会增加，而神经突的体积保持不变。这种变化是可重复的，并且与记忆巩固明显相关，因为它需要基因转录。因此，稳定的结构突触重排，包括新突触的生长，似乎是参与稳定记忆痕迹存储的昆虫和哺乳动物大脑网络的共同特性。
