slime mold decisions: another example (Introduction)

by David Turell , Tuesday, February 23, 2021, 20:24 (1367 days ago) @ David Turell

The latest study of seeming food memory:

https://phys.org/news/2021-02-single-celled-slime-mold-nervous-food.html

"The ability to store and recover information gives an organism a clear advantage when searching for food or avoiding harmful environments, and has been traditionally linked to organisms that have a nervous system. A new study authored 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.

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"The decision-making ability of Physarum is especially fascinating given that its tubular network constantly undergoes fast 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.

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"'We followed the migration and feeding process of the organism and observed a distinct imprint of a food source on the pattern of thicker and thinner tubes of the network long after feeding. Given P. polycephalum's highly dynamic network reorganization, the persistence of this imprint sparked the idea that the network architecture itself could serve as memory of the past. However, we first needed to explain the mechanism behind the imprint formation." (my bold)

"To find out what is going on, the researchers combine microscopic observations of the adaption of the tubular network with theoretical modeling. An encounter with food triggers the release of a chemical that travels from the location where food was found throughout the organism and softens the tubes in the network, making the whole organism reorient its migration towards the food.

"'The gradual softening is where the existing imprints of previous food sources come into play and where information is stored and retrieved," says Mirna Kramar, first author of the study. "Past feeding events are embedded in the hierarchy of tube diameters, specifically in the arrangement of thick and thin tubes in the network. For the softening chemical that is now transported, the thick tubes in the network act as highways in traffic networks, enabling quick transport across the whole organism. Previous encounters imprinted in the network architecture weigh into the decision about the future direction of migration."

"The authors highlight that the ability of Physarum to form memories is intriguing given the simplicity of this living network. "It is remarkable that the organism relies on such a simple mechanism and yet controls it in such a fine-tuned way. These results present an important piece of the puzzle in understanding the behavior of this ancient organism and at the same time point to universal principles underlying behavior."

Comment: A physical-chemical mechanism is shown to easily replace a complex neuron network to create a mechanism of memory. This is much more understandable attribute than how slime mold solves mazes, but offers an answer: Thick and thin tubules respond to faint chemical traces from the maze goal and draws it forward by following intensity of the trace chemical.