A neon yellow slime mold can store memories, although it lacks a nervous system. Now, scientists have found a new clue as to how the brainless spot accomplishes this impressive feat.
The single-celled organism, known as Physarum polycephalum, belongs to the taxonomic group Amoebozoa, the same group that amoebas, Live Science previously reported. The spots can exist as a small cell with a nucleus, the control center of the cell, or several cells can fuse to form a gigantic cell with many nuclei. These fused cells can grow to cover tens of square inches (hundreds of square centimeters) in area.
When they fuse, the huge cells form a complex network of internal tubes; these tubes contract, similar to blood vessels, to push fluids and nutrients through brainless gout.
The new study, published Feb.22 in the journal procedures of the National Academy of Sciences, shows that the diameters of these branched tubes can encode information, such as where the slime mold has recently found food. When the stain finds food, it quickly reorganizes its tubular network, widening some tubes and shrinking others, and this architecture remains in place even after the drops have eaten the food.
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This basic form of memory can help slime molds solve complex puzzles, such as finding the fastest route to food wave shortest way through a mazelead author Karen Alim, associate professor of biological physics at the Technical University of Munich, told Live Science in an email.
When P. polycephalum detects a nearby snack, by detecting the chemicals released by your food, the tubes closest to the food begin to dilate. Meanwhile, the tubes furthest from the food shrink and sometimes disappear completely, being reabsorbed by the sludge. The mold then crawls in the direction of the wide, dilated tubes, migrating until it gobbles up your snack.
But even after gulping down each bite of food, mold sticks to the group of thick tubes, leaving a lasting “footprint” of where the food was, the authors wrote. This dictates how the fluid flows through the entire network and influences the next direction the mold travels. For example, if more food emerges near the thick printed tubes, the slime mold is ready to spread in that direction, and that printed “memory” is reinforced.
“At brain, we store information by strengthening or weakening the connections between individual neurons, “a type of nerve cell that sends electrical and chemical signals, Alim said.” Every extra push can strengthen an existing strong connection. ”
A similar, but simplified process shapes memory formation within slime molds, he said.
And like the connections in the brain, “memories” of slimy mold can be weakened if not reinforced, Alim added. While tubes near food get thicker, tubes farther from food get thinner and they can disappear. “Memories fade as the tubes retract and disappear” into the larger slime mold, Alim said. In this way, old memories of food can be overwritten as the gout migrates and searches for new nutrients. .
Previous studies on sludge mold also hinted that “the slime mold network adapts to external cues and that the network could be used as a readout of what the slime mold experienced,” said Audrey Dussutour, researcher studying cognitive processing. in ants and slime molds at the University of Toulouse in France. The new study provides more evidence on how and why the tubular network is reorganized, Dussutour, who was not involved in the research, told Live Science in an email.
“The results remind me of ant trail networks,” where ants foraging for food leave a trail of chemicals for other ants to follow, Dussutour added. As more ants follow the same trail and deposit more chemicals, more ants are likely to follow the worn trail over another, less traveled one, according to a 2005 report that Dussutour co-authored in the journal. Proceedings of the Royal Society B.
However, while scientists know which pheromones the ants secrete to leave their tracks, it is unclear what signal tells the tubes to widen and others to shrink, Alim said.
Based on laboratory experiments and computer models of P. polycephalum, the authors suspect that mud mold produces some soluble substance when it feels food and that this substance causes the tubes closest to the food to soften and stretch. As the gelatinous walls of the tubes stretch, some of the substance seeps into the larger network of tubes and becomes more diluted the further it travels. Therefore, tubes far from the food source receive very little, if any, substance, the study authors explained.
While there is evidence that this mysterious chemical drives the tube to expand, we unfortunately have no idea of its chemical makeup, “Alim said. That will be the focus of future research.
Furthermore, “the next step is to ask how many memories can be stored in a network and if we can transfer the mechanism to synthetic systems to build intelligent materials,” Alim said. These intelligent materials would mimic the living flow networks found in the molds of slime and could be used to build soft-bodied robots, for example, according to a statement.
Originally posted on Live Science.