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