Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 118 route de Narbonne, Bat 4R4, 31062 Toulouse Cedex 9, France.
Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, 118 route de Narbonne, Bat 4R4, 31062 Toulouse Cedex 9, France; Department of Zoology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
Curr Biol. 2021 May 24;31(10):2065-2074.e5. doi: 10.1016/j.cub.2021.02.044. Epub 2021 Mar 18.
How social interactions influence cognition is a fundamental question, yet rarely addressed at the neurobiological level. It is well established that the presence of conspecifics affects learning and memory performance, but the neural basis of this process has only recently begun to be investigated. In the fruit fly Drosophila melanogaster, the presence of other flies improves retrieval of a long-lasting olfactory memory. Here, we demonstrate that this is a composite memory composed of two distinct elements. One is an individual memory that depends on outputs from the α'β' Kenyon cells (KCs) of the mushroom bodies (MBs), the memory center in the insect brain. The other is a group memory requiring output from the αβ KCs, a distinct sub-part of the MBs. We show that social facilitation of memory increases with group size and is triggered by CO released by group members. Among the different known neurons carrying CO information in the brain, we establish that the bilateral ventral projection neuron (biVPN), which projects onto the MBs, is necessary for social facilitation. Moreover, we demonstrate that CO-evoked memory engages a serotoninergic pathway involving the dorsal-paired medial (DPM) neurons, revealing a new role for this pair of serotonergic neurons. Overall, we identified both the sensorial cue and the neural circuit (biVPN>αβ>DPM>αβ) governing social facilitation of memory in flies. This study provides demonstration that being in a group recruits the expression of a cryptic memory and that variations in CO concentration can affect cognitive processes in insects.
社交互动如何影响认知是一个基本问题，但很少在神经生物学层面上得到解决。众所周知，同物种的存在会影响学习和记忆表现，但这个过程的神经基础直到最近才开始被研究。在果蝇 Drosophila melanogaster 中，其他果蝇的存在会提高对持久嗅觉记忆的检索。在这里，我们证明这是一种由两个不同元素组成的复合记忆。一个是个体记忆，它依赖于蘑菇体（MB）的α'β' Kenyon 细胞（KC）的输出，这是昆虫大脑中的记忆中心。另一个是群体记忆，需要来自 MB 的αβ KC 的输出，这是 MB 的一个不同的子部分。我们表明，记忆的社交促进作用随着群体规模的增加而增加，并由群体成员释放的 CO 触发。在大脑中携带 CO 信息的不同已知神经元中，我们确定了双侧腹侧投射神经元（biVPN），它投射到 MB 上，对于社交促进是必要的。此外，我们证明 CO 诱发的记忆涉及涉及背侧配对中缝（DPM）神经元的血清素能途径，揭示了这对血清素能神经元的新作用。总的来说，我们确定了控制果蝇记忆社交促进的感觉线索和神经回路（biVPN>αβ>DPM>αβ）。这项研究证明了处于群体中会招募隐性记忆的表达，并且 CO 浓度的变化会影响昆虫的认知过程。
