Having a memory of past events allows us to make smarter decisions about the future. Researchers from the Max Planck Institute for Dynamics and Self-Organization (MPIDS) and the Technical University of Munich (TUM) identify the basis for the formation of memories in the mucus form Physarum polycephalum – despite the lack of a nervous system.
The ability to store and recover information gives an organism a clear advantage when searching for food or avoiding harmful environments, and has traditionally been linked to organisms that have a nervous system. A new study written by Mirna Kramar (MPIDS) and Prof. Karen Alim (TUM and MPIDS) challenges this view by uncovering the surprising abilities of a highly dynamic, single-celled organism to store and retrieve information about its environment.
Window into the past
The slime form Physarum polycephalum has amazed scientists for many decades. Existing at the crossroads of the kingdom of animals, plants and fungi, this unique organism provides insight into the early evolutionary history of eukaryotes. Its body is a giant single cell made up of interconnected tubes that form intricate networks. This single amoeba-like cell can extend several centimeters or even meters, and it is the largest cell on earth in Guinness World Record Book.
The striking form’s striking abilities to solve complex problems such as finding the shortest path through a maze gave it the attribute “intelligent”, fascinated the research environment and ignited decision-making questions at the most basic levels of life. Physarum’s decision-making ability is particularly fascinating given that its tubular network is constantly undergoing rapid reorganization – growing and disintegrating its tubes – while completely lacking an organizing center. The researchers discovered that the organism weaves memories of food encounters directly into the architecture of the network-like body and uses the stored information when making future decisions.
Decisions are governed by memories
“It’s very exciting when a project evolves from a simple experimental observation,” says Karen Alim, leader of the Biological Physics and Morphogenesis group at MPIDS and TUM professor of biological network theory, “We followed the migration and feeding process in organism and observed a clear imprint of a food source on the pattern of thicker and thinner tubes in the network long after feeding.Considering P. polycephalum’s very dynamic network reorganization, the persistence of this imprint constituted the idea that the network architecture itself could serve the memory of the past. we first had to explain the mechanism behind the imprint. “
To find out what is going on, the researchers combine microscopic observations of the adaptation of the tubular network with theoretical modeling. An encounter with food triggers the release of a chemical that moves from the site where food was found throughout the organism and softens the tubes in the network, causing the entire organism to reorient its migration towards the food.
“The gradual softening is where the existing imprints from previous food sources come into play and where information is stored and retrieved,” says Mirna Kramar, first author of the study. “Previous feeding events are embedded in the hierarchy of pipe diameters, specifically in the arrangement of thick and thin pipes in the network. For the emollient chemical now being transported, the thick pipes in the network act as highways in traffic networks, enabling rapid transport throughout the organism. meetings shaped by network architecture weigh into the decision on the future direction of migration. “
Universal principles inspire design
The authors emphasize that Physarum’s ability to form memories is intriguing given the simplicity of this living network. “It is remarkable that the organism is dependent on such a simple mechanism and yet controls it in such a finely tuned way. These results form an important piece of the puzzle in understanding this ancient organism’s behavior and at the same time point to universal principles behind behavior. We envisage potential applications of our findings in the design of smart materials and the construction of soft robots that navigate through complex environments, ”concludes Karen Alim.
Test of the effects of ‘noise’ on the decision-making ability of the mucus form
Mirna Kramar et al. Coding of memory in the pipe diameter hierarchy in live flow networks, Proceedings of the National Academy of Sciences (2021). DOI: 10.1073 / pnas.2007815118
Provided by the Max Planck Society
Citation: Researchers find a single-celled mucus form without nervous system that remembers places to eat (2021, 23 February) retrieved 23 February 2021 from https://phys.org/news/2021-02-single-celled-slime-mold- nervous-food .html
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