Slime mold that saves memories without nervous system

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Researchers have identified a single-cell slime mold called Physarum polycephalum that saves memories – although it’s no nervous system.

The study published within the Proceedings of the National Academy of Sciences within the us of America was conducted by researchers at the Max-Planck Institute for Dynamics and Self-Organization (MPI-DS) and therefore the Technical University of Munich (TUM).

Having memory about the environment is vital in taking informed decisions. The concept of memory is traditionally related to organisms possessing a nervous system.

However, even very simple organisms store information about past experiences to thrive during a complex environment—successfully exploiting nutrient sources, avoiding danger, and avoiding predators.

Karen Alim, head of the Biological Physics and Morphogenesis group at the MPI-DS in Göttingen and professor for the idea of Biological Networks at the Technical University of Munich said “It is extremely exciting when a project develops from an easy experimental observation.”

Giant unicellular slime mold Physarum polycephalum responds to a nutrient source. The organism entirely consists of interlaced tubes of varying diameters.

“Given P. polycephalum’s highly dynamic network reorganization, the persistence of this imprint sparked the thought that the specification itself could function memory of the past,” says Karen Alim. However, they first needed to elucidate the mechanism behind the imprint formation.

Memory about the nutrient location is encoded within the morphology of the network-shaped organism. a nutrient source locally releases a softening agent that gets transported by the cytoplasmic flows within the tubular network.

“The gradual softening is where the prevailing imprints of previous food sources inherit play and where information is stored and retrieved,” says first author Mirna Kramar. “Past feeding events are embedded within the hierarchy of tube diameters, specifically within the arrangement of thick and thin tubes within the network.”

“For the softening chemical that’s now transported, the thick tubes within the network act as highways in traffic networks, enabling quick transport across the entire organism,” adds Mirna Kramar.

“Previous encounters imprinted in the specification thus weigh into the choice about the longer term direction of migration.”

Tubes receiving tons of softening agent grow in diameter at the expense of other tubes shrinking. Thereby, the tubes’ capacities for flow-based transport get permanently upgraded toward the nutrient location, redirecting future decisions and migration. This demonstrates that nutrient location is stored in and retrieved from the networks’ tube diameter hierarchy.

In the study, scientists identify a flow networks’ version of associative memory—very likely of relevance for the plethora of living flow networks also as for bioinspired design.

“Given the simplicity of this living network, the power of Physarum to make memories is intriguing. it’s remarkable that the organism relies on such an easy mechanism and yet controls it in such a fine-tuned manner,” says Karen Alim.

“These results present a crucial piece of the puzzle in understanding the behavior of this ancient organism and at an equivalent time points to universal principles underlying behavior. We envision potential applications of our findings in designing smart materials and building soft robots that navigate through complex environments,” concludes Karen Alim.

Source: Wion news

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