Electrical coding in fungi

In one of my articles published in mid-September, I wrote this about neural coding:

“In his book Nervous Man, Jean-Pierre Changux recounts an experiment conducted on monkeys (the species was not specified). Electrodes recorded the spontaneous activity of the vestibular nerve of an animal that was sitting in a chair that was rotated. In the absence of movement, the electrodes recorded a series of 20 pulses per second emanating from these neurons. If the chair was rotated in one direction, the frequency decreased to 10 pulses per second, and if it was rotated in the opposite direction, it rose to 30 pulses per second, and it is clear that we are facing a form of collective coding of neurons. In this Topic We can make the following observation. First of all, this method of encoding information uses the spontaneous activity of a group of neurons that continuously emit impulses. Therefore, it is a form of encoding that requires a lot of energy. Above all, these vestibular neurons can encode only two »

I have invited readers to ask whether this is the form of neural activity that characterized the beginnings of information encoding by neurons.

In this article, I want to show that this type of coding using electrical impulses exists even without neurons. Often times, the study of living organisms holds up surprises for biologists, and one field that offers its share of surprising discoveries is the field of fungal collecting. However, they are different from plants, as plants are composed of a visible part, outside the soil, and an invisible part found in the soil, the mycelium. Mycelium can be likened to the roots of a plant, whose function is to absorb the nutrients needed to nourish the body. Unlike roots, which grow by branching, mycelium forms a network with several interconnected nodes. This network can sometimes extend over a very long distance. This type of fungal network usually develops where there are plants, and for good reason, because their roots provide them with the food the fungi need.

A network of electrical impulses

A fungal network is reminiscent of a neural network, and this is not the only connection that can be made between the two types of structures. Already in the last century, it was discovered that the mycelium of several species of mushrooms generate electric currents¹. This observation was interesting in itself already. What is the purpose of passing electrical currents through the “root” network of mushrooms? Especially since this type of network is coated with proteins that act as an insulating cover, thus ensuring good electrical conductivity over long distances without losing much energy, such as the myelin surrounding the axon of nerve cells. Furthermore, the cells in this network are adjacent, allowing signals to be transmitted from one end of the network to the other.

One researcher assumed that this type of electrical transmission was used in the communications system. By inserting electrodes into specific locations in the mycelium, he recorded regular pulses in Armillaria species at a rate of 4 beats per second, very close to sensory neurons in animals. This species’ fungal networks can stretch for miles and appear to live for thousands of years. He then placed a piece of wood in contact with the mycelium and observed that the rate of electrical pulses emitted doubled. By removing it, the rhythm returned to normal. Wood is a food source for fungi. He replaced the block of wood with a block of plastic: the fungal network did not react this time. He repeated this type of experiment with other types of mushrooms that grow on plant roots and obtained the same results.^2-3.

Information encryption has been demonstrated using the same method as above, but this time in the fungi kingdom. Note here, however, that the encoding seems to work in only one direction: the increase rather than the decrease in the rhythm of the electrical impulses. Which will be simpler than the binary encoding mentioned in my article that I mentioned. When did this phenomenon appear? The undisputed oldest fossils of the web of fungi date back to about 400 million years ago⁴. Does the emergence of information encoded by electrical pulses go back to this distant era?