The giant unicellular slime mold encodes memories about the location of nutrients by changing the diameters of tubes within its network-like body, a study finds. Giant slime molds can quickly make decisions and solve complex problems, despite not having a nervous system. How this nonneuronal organism encodes memories about the environment is unclear. Mirna Kramar and Karen Alim collected a time-series of bright-field images to observe the foraging behavior of the giant unicellular slime mold. Approximately 15 minutes after a single, local nutrient source was applied nearby, tubes throughout the network changed their diameter, imprinting the nutrient location in the hierarchy of thinner and thicker tubes. This reorganized network persisted for 30 minutes, until the organism started to migrate toward the nutrient source. A theoretical model combined with experimental data suggested that the nutrient source releases a soluble chemical that enters the network and locally softens the tube wall. The chemical triggers the dilation of tubes that are quickly reached by flow-based transport, at the expense of other tubes that shrink due to conservation of fluid volume. According to the authors, this mechanism may underlie memory formation in other living flow networks and could be harnessed to design biomimetic materials and soft robots.
Article #20-07815: "Encoding memory in tube diameter hierarchy of living flow network," by Mirna Kramar and Karen Alim.
MEDIA CONTACT: Karen Alim, Technical University of Munich, GERMANY; email: firstname.lastname@example.org
Proceedings of the National Academy of Sciences