Yoneoka Emiri, Takamatsu Atsuko
Department of Electrical Engineering and Bioscience, Waseda University, Tokyo, Japan.
Front Cell Dev Biol. 2023 Nov 10;11:1249165. doi: 10.3389/fcell.2023.1249165. eCollection 2023.
The question of whether a single-celled organism without a brain could have functions such as learning and memory has been the subject of much debate in recent years. The plasmodium of the true slime mold, , is an ideal model organism for such a question. The plasmodium exhibits behaviors that resemble intelligence, including solving mazes, mimicking optimal rail transportation networks, predicting the weather, and solving traveling salesman problems. In addition, the plasmodium has recently been shown to have the simplest form of learning: habituation. In the experiments in which plasmodia were repeatedly allowed to cross bridges containing aversive chemicals, the habituation behavior has been confirmed. It has been shown that the habituation process involves chemicals that are stored internally. However, it is not clear how these chemicals result in change in the behavior of plasmodium during habituation learning. This study focused on the transport tube network formed in plasmodium during the above experiments. Then, the role of the network morphology in the habituation learning process was investigated. The results showed that the network morphology changes from tree to mesh type during habituation learning, and disrupting the learned network reduces habituation behavior. In addition, it was shown that the thickness oscillation frequency depends on the network morphology. The study found that in the plasmodium of , a primitive organism without a brain, transport tube networks, instead of neuronal networks, play an important role in habituation learning and the resulting decision making.
近年来，关于没有大脑的单细胞生物是否能具备学习和记忆等功能的问题一直是诸多争论的焦点。真正的黏菌的疟原虫是研究此类问题的理想模式生物。疟原虫表现出类似智能的行为，包括解决迷宫问题、模仿最优铁路运输网络、预测天气以及解决旅行商问题。此外，最近研究表明疟原虫具有最简单的学习形式：习惯化。在让疟原虫反复穿越含有厌恶化学物质的桥梁的实验中，习惯化行为得到了证实。研究表明，习惯化过程涉及疟原虫内部储存的化学物质。然而，尚不清楚这些化学物质如何在习惯化学习过程中导致疟原虫行为的改变。本研究聚焦于上述实验过程中疟原虫形成的运输管网。随后，研究了网络形态在习惯化学习过程中的作用。结果表明，在习惯化学习过程中，网络形态从树状变为网状，破坏已形成的网络会降低习惯化行为。此外，研究表明厚度振荡频率取决于网络形态。该研究发现，在没有大脑的原始生物疟原虫中，运输管网而非神经网络在习惯化学习及由此产生的决策过程中发挥着重要作用。
