A
new brain implant based on intracortical microelectrodes can allow a
blind person to see shapes and letters. New research by the Miguel
Hernández Univresity (UMH) of Spain shows that the implantation of this
micro device in the human brain can be done safely, and that the direct
stimulation of the cerebral cortex produces visual perceptions with a
much higher resolution than had been achieved until now. The Biomedical
Engineering group of the UMH, led by Cellular Biology Professor Eduardo
Fernández Jover, has published the results of the experiment in the Journal of Clinical Investigation.
In
December 2020, this same team of researchers carried out a similar
experiment by stimulating the visual cortex of primates. An implant with
over 1,000 electrodes was used in that case, allowing the animals to
see shapes, movement and letters. However, the animals were not blind.
"This study goes a little further. We have implanted [the micro electrodes] in the brain of
a person who has been completely blind for over 16 years," says Jover,
who is also a member of the Centre for Biomedical Research Network in
Bioengineering, Biomaterials and Nanomedicine. The volunteer, a
57-year-old woman, has been able to identify letters and even the
silhouette of some objects.
This is the first time that a brain implant of this type has been performed in a blind person,
and professor Eduardo Fernández explains that the results are
encouraging for the development of a visual neuroprosthesis that can
help blind people or those with low or residual vision to improve their
mobility, and even in a more ambitious way, to perceive their
surroundings and orient themselves. However, the UMH researcher adds
that, although the results of this and other studies are promising,
there are still many issues to solve, which is why steps must be taken
gradually and false expectations must not be created. For now, it is an
ongoing investigation.
Watch Video: https://youtu.be/HQyk1d92Oc8
Credit: Universidad Miguel Hernández de Elche
For
six months, the researchers performed experiments in which the
volunteer had to try to identify letters, their position and the shape
of different objects. These took place several times to observe the learning process of the person's visual cortex and to see possible changes.
The
implanted device is a small, three-dimensional matrix with 100 micro
electrodes that communicates with the brain cells in a bidirectional
way: It registers electric signals and stimulates the brain. It is 4
millimeters wide, with electrodes that are 1.5 mm long. One of the
conclusions of the study is that this does not impact the function of
the brain cortex or of the neurons next to the implant.
The
UMH researcher explains that the results of this new study show that
implanting and explanting this type of micro-device can be performed
safely for humans, and that the electric stimulation of these
electrodes, which penetrate the cerebral cortex, can safely induce visual perceptions with
much higher resolutions than those achieved previously. Fernández Jover
says, "The amount of electric current needed to induce visual
perceptions with this type of microelectrode is much lower than the
amount needed with electrodes placed on the surface of the brain, which
means greater safety."
Watch Video: https://youtu.be/pPqluZ5z7xM
Credit: Universidad Miguel Hernández de Elche
The
full stimulation system includes an artificial retina which emulates
the operation of the human visual system, which is placed in regular
glasses. The artificial retina captures
the visual field in front of the person and transforms it into streams
of electrical impulses that are optimized to stimulate the neurons of
the visual cortex via the small micro electrodes. "Thanks to this, the
implanted person was able to recognize several complex stimulation
patterns and accurately perceive shapes and letters," explains the UMH
professor. Furthermore, there is a learning process over time, meaning
that with the appropriate training, it becomes easier to recognize
different patterns. To help her with the learning process, the
researchers created several videogames, such as a variation of the
classic Pac-Man, and a game based on the popular television series "The
Simpsons."
In
the context of this research, professor Fernández Jover says that
developing visual neuroprosthesis is a necessity for the future, as
there are no useful treatments or aid devices for many blind people. For
example, patients with advanced degenerative diseases of the retina,
severe glaucoma or pathologies that harm optical nerves, cannot benefit
from the modern retina prostheses that are being developed in some
centers. In these cases, information from the surroundings must be sent
straight to the part of the brain that processes vision, and the results
of this study, while preliminary, indicate that this is possible, and
that even after many years of total blindness, the human brain can still process visual information.
The
research team is currently recruiting new blind volunteers to take part
in these experiments. In upcoming studies, they hope to use a more
sophisticated image coding system that can stimulate more electrodes
simultaneously, in order to reproduce more complex visual images.
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