It may be a single-celled organism, but the mold is slender Physarum polycephalum very interesting tricks up the very yellow sleeves. Now new research has found that he seems to “remember” where he found previous food sources – even without a brain or nervous system.
This could help explain how network organisms can not only survive, but thrive, in complex environments, the researchers said – and that could be is a key means of understanding memory formation techniques in such species.
P. polycephalum one of the most unique forms of life on Earth. It is not a plant, animal or fungus, but a species of complex single-celled amoeba of the Protestant realm (a type of the captive group for anything that cannot be neatly classified in the other three kingdoms).
Early in life, P. polycephalum it exists as a single cell with one nucleus, but later combines with other cells to form one large cell with millions of nuclei inside.
This is the plasmodium level, and the organism can grow to cover an area up to several square meters. Its body is made up of a complex network of interconnected pipes, and that pressure creates a flow between different regions. This network can grow rapidly and reorganize to make the most of the environment.
A Plasarium Physarum. (Carolina biological supply company / Flickr / CC BY-NC-ND 2.0)
In 2000, the Japanese researcher Toshiyuki Nakagaki of RIKEN discovered that P. polycephalum able to solve simple rounds to reach a food source. Since then, scientists have discovered a number of similar behaviors of understanding, such as being able to solve the travel salesman problem, and ‘remembering’ materials.
In his latest trick, the biological physicists Mirna Kramar and Karen Alim of the Max Planck Institute for Dynamics and Self-Organization in Germany have discovered, P. polycephalum using the true architecture of his body to store memories of where he had found food before.
“We followed the process of migration and feeding of the organism and saw a unique detail of a food source on the pattern of thick and thin tubes of the network long after feeding,” Alim explained.
“Given P. polycephalumWith the reorganization of a truly dynamic network, the sustainability of this print inspired the idea that the architecture of the network itself could be a reminder of the past. However, first we needed to explain the mechanism behind the creation of the print. “
Using microscopic observations, they carefully studied how the organism organized itself around a food source. They then used theoretical modeling to understand what was going on within the slime model during that process.
They concluded that locating a food source removes a chemical that softens the wall of the tube at the local food site. This in turn causes the tubes to go down, becoming wider, to accelerate movement within the slime model to the site.
The chemical also signals to the entire organism where the food is found, so that it can move toward the site and focus on feeding.
P. polycephalum it can recycle parts of its body if it extends test tubes into an area that is unstable, or in which there is nothing of interest. But once it has found and eaten nutritious food, these thick tubes are in place so that it can quickly return to the site should food reappear, the researchers found.
“The gradual reduction is where the existing tokens of food sources come in and where information is stored and retrieved,” Kramar said.
“Feeding events in the past are based in tube diameter hierarchy, especially in the arrangement of thick and thin pipes in the network. For the soft chemical now carried, the tubes are network thickets act as highways in traffic networks, enabling rapid transport throughout the organism.A previous encounter in the network architecture emphasizes the decision on the direction of migration at the time to come. “
This is not entirely unlike how the human brain works. One has to be careful drawing parallels between a slime mold and the human brain, but there are some interesting things that can help us understand how information coding works in different types of growth -members.
In this case, synapses, which pass information between neurons, strengthen as we learn and become stronger as we use them, but they can become weaker if we don’t. we do that – much like the tubes of the slime hill, which thicken at sites of interest, but will die or be recycled if their presence is no longer useful to the organism.
“It is remarkable that the organization relies on such simple equipment and yet controls it in such a swift manner,” Alim said.
“These results represent an important piece of the puzzle in understanding the behavior of these ancient organisms while at the same time pointing to universal principles that underpin behavior. We explores potential applications for the design of smart products and the construction of soft robots that navigate complex environments. “
The research was published in PNAS.