Chip Neuron
An electronic analog neuron has been created at the University of Bath
Madrobots company blog, Habr
A team of scientists from the University of Bath has developed an electronic device that, according to the developers, copies the behavior of neurons (Abu-Hassan et al., Optimal solid state neurons // Nature Communications 2019). So far, an artificial neuron plays the role of only one of the types of human nerve cells that work in the brain – those that are responsible for breathing and heartbeat.
Nevertheless, the developers said that their technology makes it possible to create other neurons, both those that work in the brain and those that are located in nerve endings throughout the body. The main task performed by "electronic neurons" is to reproduce the electrical activity of real cells.
And not just activity, but the work that a real neuron would do if it were connected to other cells. This is something like an analog simulator that does not perform calculations and does not work with a "digit".
It is worth noting that the idea underlying the project is not new. It was expressed by scientists Alan Lloyd Hodgkin and Andrew Huxley in the middle of the XX century. They suggested that the neuron could be reproduced artificially. To do this, you need to use a membrane that works as an electrical circuit. It, in turn, consists of four different elements, including a capacitor and three independent ion channels with variable conductivity.
Scientists have also developed a mathematical model that describes the operation of ion channels with variable conductivity. As it turned out, this model really works, but only in theory and in experiments related to electricity.
And there is a need to create an artificial neuron, because this is the only way to restore, for example, a damaged nervous system. But the added elements that replace artificial or damaged ones should work like real neurons.
This problem is solved by an artificial neuron developed under the guidance of scientist Alain Nogare. According to scientists, there is a specific electrical circuit in an artificial neuron, it makes it possible to reproduce the reaction of a real neuron to external factors.
The disadvantage of the development now is the large size of the device. This is a chip on a silicon chip. But the system is fully consistent with both the Hodgkin-Huxley model and newer models. The accuracy of the chip is about 96%.
The scientists decided to test the work of the neuron, for which they modeled a real system – pyramidal cells of the hippocampus and neurons of the rat respiratory center. This system was chosen because of its excellent knowledge: scientists know how and where nerve cells are located, and they also know the ratio of neurons. As a result, it turned out that artificial neurons can be used to create artificial analogues, provided that six types of model ion channels are introduced with a specific algorithm of operation.
Then different sequences of electrical signals were tested on the created systems. As it turned out, the pulse reproduction accuracy was very close to real conditions – from 94% to 97%.
After information about the study appeared online, it was said about the project that it could become the main one for the treatment of diseases associated with damage to the nervous system. However, this is not entirely true, the practical use of the results of the project is still very far away.
The main problem is that the "neuron" chip is very large. Implanting it into the body is not an easy task, which is complicated by the fact that it is still necessary to create connections between artificial cells. These connections form channels that conduct electric current.
Nevertheless, the direction of developing simple bionic prostheses, as well as interfaces for connecting the human nervous system with a computer, is quite promising. There is already a possibility of using chips here, so the authors of the project will probably study this possibility in the near future.
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