Scientists
have created key parts of synthetic brain cells that can hold cellular
"memories" for milliseconds. The achievement could one day lead to
computers that work like the human brain.
These
parts, which were used to model an artificial brain cell, use charged
particles called ions to produce an electrical signal, in the same way
that information gets transferred between neurons in your brain.
Current computers can do incredible things, but this processing power comes at a high energy cost. In contrast, the human brain is remarkably efficient, using roughly the energy contained in two bananas to do an entire day's work.
While
the reasons for this efficiency aren't entirely clear, scientists have
reasoned that if they could make a computer more like the human brain,
it would require way less energy.
One
way that scientists try to replicate the brain's biological machinery
is by utilizing the power of ions, the charged particles that the brain
relies on to produce electricity.
Related: Inside the brain: A photo journey through time
(Paul Robin, ENS Laboratoire de Physique (CNRS/ENS-PSL/Sorbonne Université/Université de Paris)
Above: The researchers' artificial neuron prototype.
In the new study, published in the journal Science on
Aug. 6, researchers at the Centre national de la recherche scientifique
in Paris, France, created a computer model of artificial neurons that
could produce the same sort of electrical signals neurons use to
transfer information in the brain; by sending ions through thin channels
of water to mimic real ion channels, the researchers could produce
these electrical spikes.
And now, they have even created a physical model incorporating these channels as part of unpublished, ongoing research.
"To
my knowledge, it's the first time that people [have done] this with
ions," said study co-author Lydéric Bocquet, a physicist at the École
Normale Supérieure.
At
a finer level, the researchers created a system that mimics the process
of generating action potentials – spikes in electrical activity
generated by neurons that are the basis of brain activity. To generate
an action potential, a neuron starts to let in more positive ions, which
are attracted to the negative ions inside of the cell.
The electrical potential, or voltage across
the cell membrane, causes doorways on the cell called voltage-gated ion
channels to open, raising the charge even more before the cell reaches a
peak and returns to normal a few milliseconds later. The signal is then
transmitted to other cells, enabling information to travel in the
brain.
To mimic voltage-gated ion channels, the researchers modeled a thin layer of water between sheets of graphene,
which are extremely thin sheets of carbon. The water layers in the
simulations were one, two, or three molecules in depth, which the
researchers characterized as a quasi-two-dimension slit.
Bocquet
said that the researchers wanted to use this two-dimensional
environment because particles tend to react much more strongly in two
dimensions than in three, and they exhibit different properties in two
dimensions, which the researchers thought might be useful for their
experiment.
"In physics, two dimensions is very weird," said Bocquet. "So you expect new things to occur."
Testing
out the model in a computer simulation, the researchers found that when
they applied an electric field to the channel, the ions in the water
formed worm-like structures.
As
the team applied a greater electric field in the simulation, these
structures would break up slowly enough to leave behind a "memory," or a hint of the elongated configuration.
When
the researchers ran a simulation linking two channels and other
components to mimic the behavior of a neuron, they found the model could
generate spikes in electrical activity like action potentials, and that
it "remembered" consistent properties in two different states – one
where ions conducted more electricity and one where they conducted less.
In
this simulation, the "memory" of the previous state of the ions lasted a
few milliseconds, around the same time as it takes real neurons to
produce an action potential and return to a resting state.
This
is quite a long time for ions, which usually operate on timescales of
nanoseconds or less. In a real neuron, an action potential equates to a
cellular memory in the neuron; our brains use the opening and closing of
ion channels to create this kind of memory.
"We have similar memory in the end, but the reason for the phenomenon is very different," Bocquet said.
The
new model is a version of an electronic component called a memristor,
or a memory resistor, which has the unique property of retaining
information from its history. But existing memristors don't use liquid,
as the brain does.
"The
typical memristors that I work with, and other people in the literature
work with, are solid-state memristors," said Gina Adam, an assistant
professor of electrical and computer engineering at George Washington
University, who was not involved in the study. This new research on
creating fluid memristors is "very promising and very intriguing," Adam
added.
She
also said that while practical brain-like computers are likely a long
way away, this research could also help scientists better understand how
the brain processes information and develop new theories of brain-like
computing.
Since
conducting this research with computer simulations, Bocquet says he and
collaborators at the University of Manchester in the UK have brought
their theory to life, using it to create an artificial synapse, the part
of a neuron that passes on electric signals, and they have started
performing experiments with it.
"It's exciting because it's a playground now," Bocquet said. "We can explore these things actively."
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This article was originally published by Live Science. Read the original article here.