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Friday, 13 August 2021

Study suggests ‘memories’ can be stored in synthetic brain cells


Three researchers from the Physics Laboratory of the École Normale Supérieure in Paris, France, recreated in a model the electrical charge transport system that characterizes a nerve cell.

The experiment involved placing an aqueous electrolyte, similar to the one that fills neurons, in a very fine and almost two-dimensional space, and the desired effect was the imitation of intracellular functions associated with memory.

Most of the memory artificial resistor systems, known in professional parlance as ‘memristors’, use electrons as charge carriers, but an ion solution can also transmit charge. And that’s precisely the way neurons work, scientists argue in a published article last Friday in the journal Science. In his tests, that liquid was confined between two layers of graphite barely spaced from each other by a ten-billionth of a meter.

In general, under the effects of an electric field, ions assemble into elongated groups – ones worm-like structures– and show slow dynamics and voltage typical for intracellular transmission, the researchers observed. This phenomenon promotes the ‘memristor’ effect, and the team believes that it can be used to build an artificial neuron.

Lydéric Bocquet, study co-author, think That this is the first time it has been possible to incorporate to a physical model the neural transmission channels, which are the basis of brain activity. He also explains that the team opted for an almost two-dimensional environment, very rare for nature, because in two dimensions the particles tend to react more strongly than in three and exhibit different properties.

To generate an action potential in a real, living brain, a neuron lets in a group of positive ions, attracted by other negatively charged ions. The electrical potential, or voltage, passes through the cell membrane and causes ‘doors’ known as ion channels open in the cell. Meanwhile, the possibility of activating them with the accumulated electrical charge implies that it reaches a peak before the entry of the ions and returns to normal a few milliseconds later. The signal is then transmitted to other cells, which allows information to travel through the brain.

Scientists suppose that this mechanism could serve, probably in the distant future, to develop computers as ‘energy efficient’ as brain tissue and, more immediately, to help scientists better understand how the brain processes information. The tests carried out are part of the attempts to develop an artificial synapse, that is, the connection that transmits electrical signals between two neurons or from one neuron to another cell.

Reference: 

Modeling of emergent memory and voltage spiking in ionic transport through angstrom-scale slits” by Paul Robin, Nikita Kavokine and Lydéric Bocquet, 6 August 2021, Science. DOI: 10.1126/science.abf7923

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