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FUNCTIONALITY OF COGNITIVE NEUROPROSTHETICS FOR
MECHANICAL PROSTHETIC INTEGRATION
Josh Tarlo, [email protected], Vidic 2:00, Peter Gibson, [email protected], Mahboobin 4:00
Abstract—Until recently, prosthetics have been crude devices
that have only restored basic control to an amputee. This
paper will explore the technology behind cognitive
neuroprosthetics, specifically the brain-machine interface
that allows an amputee to control their prosthetics through
conscious thought.
This subset of technology provides patients the use of
prosthetics by redirecting brain signals through computer
components instead of the peripheral nervous system. This
allows people who suffer from paralysis or other peripheral
nerve damage to utilize prosthetic technology, expanding the
population of patients that can benefit from it.
Cognitive neuroprosthetics have two basic components:
the brain-computer interface (BCI) and the physical
prosthetic. The BCI receives information from the brain and
returns information that the user perceives as their normal
senses. The information that the BCI uses is either commands
to manipulate the physical prosthetic, or information inputted
from the physical prosthetics sensors. While these are the
basic components, there are many smaller components that
were developed independently to make up the whole cognitive
neuroprosthetic.
This paper focuses on three distinct studies. These
studies describe the creation of tactile feedback in cognitive
neuroprosthetics and their implementation and training in
both humans and primates, which demonstrate that cognitive
neuroprosthetics can be used by subjects with limited
experience in using the biological equivalent to the
mechanical prosthetic.
Ethical concerns also follow the use of neuroprosthetics,
including risky surgery with small potential for direct benefit,
issues with continued informed consent, and psychological
risks for patients. In the future, it is highly plausible that
neuroprosthetic interface technology will improve with new
scientific research about the brain and how it functions,
decreasing risks of the surgery and use related to the
prosthetic. This will make neuroprosthetics a safer option to
increase mobility in those who cannot use regular mechanical
prosthetics.
Key Words—Brain-Computer Interface, Central Nervous
System, Cognitive Neuroprosthetics, External Mechanical
Prosthetics, Rehabilitation Sciences
University of Pittsburgh Swanson School of Engineering
Submission Date: 03.03.2017
1
TODAY’S PROSTHETICS: POWERED
BY THE MIND
Various types of prosthetic limbs have had many issues
throughout their existence, such as difficulty of control and
lack of realistic sensation in the prosthetic. However, recent
developments in this area have started to eliminate these
problems. The integration of Brain-Computer Interfaces
(BCI) into a new generation of prosthetics, called cognitive
neuroprosthetics, allows an amputee to control their
prosthetics using conscious thought.
According to Dr. Anderson of California Institute of
Technology, a cognitive neuroprosthetic is a technology that
uses electrodes implanted in the brain to record and analyze
the cognitive state of the user, rather than strictly analyzing
the motor signals being sent through the body [1]. This type
of technology can be applied to patients who are capable of
planning physical movement, but due to an injury or
disability, are unable to execute them. Cognitive
neuroprosthetic technology allows more patients to use
mechanical prosthetics for limb replacement since, unlike
many other prosthetic mechanisms, the neuroprosthetics
receive and decode signals directly from the brain. Due to the
technology bypassing the central nervous system, even
paralyzed patients could regain movement through a
combination of mechanical and cognitive neuroprosthetic
technology.
While this new technology may prove useful in the
future, it is currently in its infancy; hence there is very little
direct benefit to using a cognitive neuroprosthetic. To use a
neuroprosthetic, an amputee must undergo extensive brain
surgery and live with foreign electrodes in their brain. These
foreign objects could have many undetermined effects on
their body and mind. In addition, it is possible that the
technology will not function for some users. Because of this,
the utilization of neuroprosthetics raises ethical questions
concerning the safety of the patients. Furthermore, as with
many young technologies, few people have heard of it, which
causes some distrust in potential consumers. This makes it
challenging for amputees to obtain neuroprosthetics, because
few insurance companies are willing to cover the cost of the
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devices. Because the technology is still developing and not
well-known technology, production is currently costlier to
than it is possible to earn by selling devices, making their
current business model unsustainable. This clearly shows that
the technology is not risk free, but is developing and will
continue to be further improved to create a more widely
available and useful technology.
then sent to a computer to decode the information [2]. The
BCI’s method of returning sensation into the missing limb “is
to directly stimulate the neurons in the corresponding intact
somatosensory cortex which normally receives sensory
signals from the limb” [2]. So, if the user has had their hand
amputated, the BCI sends electrical signals into the part of the
somatosensory cortex that corresponds to their hand with a
current no more than 100μA [2]. As seen in Figure 1 (below),
there are very specific parts of the brain that correlate to
specific areas on the hand. These must be mapped out on the
BCI’s electrode arrays, so the user can properly perceive
which part of the physical prosthetic is touching contacting an
object. This allows the user to have better control over the
prosthetic limb because they have touch feedback that typical,
able-bodied people have.
NEUROPROSTHETICS, BCI, AND THEIR
USES
To understand how cognitive neuroprosthetics work with
the mechanical prosthetics, one must first understand these
two main components of the system. The first component is
the Brain-Computer Interface made of a series of electrodes
that send, receive, and interpret information between the brain
and the hardware. The second is the physical prosthetic, the
mechanical device that moves in response to the signals
received and interpreted by the BCI.
Brain Computer Interface
The Brain-Computer Interface acts as a messenger
between the user’s conscious thoughts and the physical
prosthetic. The main component of a BCI is one or more
electrode arrays that are surgically implanted directly onto the
brain. These electrodes are made of materials such as
sputtered iridium oxide, electrically isolated from each other
by Parylene-C polymer and nonconducting glass, and
attached to a silicone base [2]. These allow for precise
detection and stimulation of electrical currents in specific
parts of the brain. However, after long-term use, the signals
from these electrodes can decrease in strength and quality,
potentially due to “long-term encapsulation of the electrodes
by glial scarring,” which can physically and electrically
isolate the electrode from the target neurons [1].
Alternatively, less popular non-invasive BCI can be utilized
to operate cognitive neuroprosthetics. The difference between
the two kinds of BCI is that instead of using electrodes
implanted into the brain, non-invasive BCI use
electroencephalograms (EEG) to measure brain activity.
These EEG are external devices that are placed over the user’s
scalp to detect brain signals. According to Dr. Stephan
Waldert from University College London Institute of
Neurology, this can allow for a greater area of coverage for
reading brain signals, but cannot always get as accurate of a
signal, due to distortion from the layers of tissue between the
brain itself and the EEG [3]. While they have different levels
of efficacy for different tasks, both of the two kinds of BCI
are able to complete their one main purpose.
The purpose of the BCI is to read the user’s brain signals,
interpret them as movement in the physical prosthetic, and in
certain cases, send feedback to the user that they interpret as
the sensation of touch. The BCI receives information from the
brain at a 30kHz frequency with 16-bit resolution, which is
FIGURE 1 [4]
Parts of the hand and corresponding locations on the
brain and BCI
Measuring the user’s thoughts in order to move the
physical prosthetic can make the device easier to operate.
Myoelectric prosthetics, originally created by Reinhold Reiter
just before 1950, base their movements from actions in the
user’s residual limb. Myoelectric prosthetics have electrodes
in the socket that attaches to the residual limb [5]. These
electrodes then measure the electrical signals received from
the peripheral nervous system and the muscle movements in
the residual limb, and then uses that input from the user to
move the hand and wrist of the prosthetic in the desired
manner through motorized movements. While these
movements correspond to the manipulation of a typical hand,
it can still be confusing and hard to learn to use these devices
properly. This type of prosthetics requires the user to think
and move a different way than they would normally. Because
of this, myoelectric prosthetics take much longer than a
neuroprosthetic system to learn. An amputee training with a
neuroprosthetic can have partial autonomous control of the
device. The partially automated control acts as a sort of
“training wheels” while the amputee adjusts and learn how to
use the new limb replacement. This allows the user to
gradually adjust to life with a neuroprosthetics and become
more adept than they would be with a myoelectric device.
Additionally, because brain implants bypass the
peripheral nervous system, they can be utilized by people who
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were formerly unable to use prosthetics, such as someone who
has suffered a spinal cord injury. Myoelectric prosthetics base
their movements from motions in the residual limb of the user,
so, if an amputee also had nerve damage or another form of
paralysis in their residual limb, they would be unable to use a
myoelectric prosthetic. However, their brain is most likely
still intact, allowing for the BCI to send and receive
information from the user’s brain. The technology allows
users with spinal cord injuries to interact with their
surroundings in a way similar to how they would before they
were injured. Amputees suffering from nerve damage can not
only operate the prosthetic using the BCI, but the BCI can also
evoke “tactile sensations perceived as originating from
locations on the hand” that allow them to feel their
surroundings through the neuroprosthetic [4]. Yet, the vast
improvements in BCI and neuroprosthetic technology would
not be possible without their integration into a physical
prosthetic system.
tactile sense is created due to the mimicry of the electrical
signals that a real limb would output to the brain when a limb
receives an external physical stimulation [2]. This provides a
faster and more efficient way of obtaining information on the
state of the mechanical prosthetic, as it acts and feels more
like a real part of the body rather than a purely mechanical
system for the user to use with the surrounding environment.
Because of the direct feedback into the brain, the user is
capable of using the limb with increased functionality and
accuracy compared to a mechanical prosthetic with a nondirect method of feedback.
TRIALS USING COGNITIVE
NEUROPROSTHETICS
These different technologies used in cognitive
neuroprosthetics were not all developed instantaneously.
Many different research projects were performed to help
create the different aspects that make neuroprosthetics
possible. Studies had to be performed to develop brain sensors
to detect and analyze the user’s thoughts, learn how to
interpret those brain signals and translate them into
movement, and effectively move the physical prosthetic and
use it to provide sensory feedback back to the user. All these
findings have been combined into the extraordinary
technology that is currently available. However, one must
learn about the smaller components of a cognitive
neuroprosthetic and their development to their usefulness in
society today and in the future.
Physical Prosthetic
The BCI transmits the commands of the patient to a
physical, mechanically enabled prosthetic limb, where the
commands are executed through physical movements of the
prosthetic limb. Sensors in the prosthetic control the
positioning of the certain rotational axes where joints in a
regular human limb would be located. This allows the system
to create very precise and accurate movements as per to the
patient’s request. Another benefit of these prosthetics are their
wide range of motion, meaning that the mechanical prosthetic
can execute various degrees of freedom, such as 3D
translation, roll, pitch, and yaw of the wrist, and varying
finger positions as well many other possible movements and
orientations. However, the neuroprosthetic needs to recognize
cognitive function relating to these individual movements and
translate the data to usable commands to take advantage of the
full range of motion of the prosthetic device [6].
In addition to extending range of movement and
extending the usability of mechanical prosthetics to patients
with spinal injuries, cognitive neuroprosthetics can induce the
illusion of tactile feedback to the user through the prosthetic.
In some circumstances, instead of restoring tactile feedback
to a user without a neuroprosthetic device, a method called
sensory substitution is enacted, “whereby an intact sensory
system such as vision, hearing or cutaneous sensation
elsewhere on the body is used as an input channel for
information related to the prosthesis” [2]. The downside of
this method of feedback is that it is unnatural to substitute one
sense for another, and users need to learn how to effectively
use the new sensory system, which can prove difficult due to
the indirect nature of the alternative tactile feedback through
senses such as visual or auditory. An alternative to this is to
directly stimulate the neurons in the somatosensory cortex of
the brain, which would not be possible without the use of the
neuroprosthetic to provide the stimulation [2]. By stimulating
certain regions of the somatosensory cortex, the illusion of the
Tactile Feedback Using Brain-Machine Interfaces
After receiving an input from the brain, it is possible for
a neuroprosthetic to send an output to the brain. That is, the
neuroprosthetic must use the BCI to send information in the
form of sensory feedback to the brain based on what the
sensors on the physical prosthetic detect. The original test
subject in a study at California Institute for Technology for
neuroprosthetic development was a primate. The subject had
five different electrode arrays implanted in their skull, and
once the electrodes were working, the researchers gave the
primate’s hands tactile stimulus. Computers connected to the
electrodes would detect “if a recorded multiunit cluster was
modulated while [the researchers] were probing the hand (i.e.
brushing and poking),” and they would “narrow down the
probing area” [2]. This would allow the researchers to locate,
with high specificity, the locations of different brain areas that
correspond to different tactile sensations on the body.
Afterwards, the subject’s brain was stimulated as the
neuroprosthetic interacted with the environment, which the
user feels as a sense of touch. This allows for more sensitive
calibration for the user of a cognitive neuroprosthetic, giving
them more precise control.
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FIGURE 2 [2]
Setups used in trials with virtual prosthetics
FIGURE 3 [6]
Setup for the two robot trials. Includes axes for 6 of the 7
degrees of freedom for the robot.
Furthermore, giving the user sensation in their
neuroprosthetic allows a more realistic movement of the
prosthetic, with the ease of not constantly having to look at
the artificial limb or relying on indirect tactile feedback. In
this experiment conducted by the California Institute of
Technology, the primate used a virtual prosthetic for ease of
implementation. The primate was then put in a setup where a
mirror, reflecting a computer monitor that displayed the
virtual prosthetic, obscured the primate’s view of its own arm,
only allowing it to see the prosthetic (above). The primate test
subject underwent trials where it had to touch one of two
different virtual objects (the target and the distractor), each
corresponding with a different stimulus from the electrodes.
When the primate used the virtual prosthetic in combination
with sensation from the BCI, the researchers “found that the
success rate was significantly above chance,” and the primate
could more easily discriminate between the target object and
the distractor to complete the desired task [2]. This study
demonstrates that using a neuroprosthetic that can return
sensation is easier to use and more intuitive than a myoelectric
device. Cognitive neuroprosthetics will allow for a better
quality of life, and as this demonstrated, a much easier
training regimen to adjust to life with the prosthetic.
Prior to this trial, neuroprosthetics had already
successfully controlled robotic systems; however, this
experiment focused on the logistical side, including data
filtration for information gathering of the brain and methods
to train the user to effectively control and utilize the
neuroprosthetic-robotic arm system. In order to calibrate the
neuroprosthetic and use it to receive useful information from
the brain, the monkeys were placed in a chair onlooking a 2robot system configuration: where one robot holds a target,
and the other robotic arm, which is controlled by the BCI
implanted in the primate’s brain, must reach for the target, as
seen in Figure 3 (above). When the monkey pressed a button,
the robot holding the target would move to a new location,
and the robotic arm with the hand would move and grasp the
target autonomously. When the robotic arm grasped the
target, the monkey received a liquid reward [6]. However,
with the monkey paying attention, the neuroprosthetic was
able to recreate a control system by recording the spikes in
activity in the monkey’s brain and comparing them to the
movements of the robotic arm that it was looking at. This
process calibrated the neuroprosthetic by filtering out brain
activity that it did not need and learn to correlate specific
spikes in activity with certain movements of the arm,
including direction and velocity of the arm [6]. This calibrated
system was then used in reverse, using the information and
spikes gathered from the monkey’s brain to control and
operate the robotic arm to grasp the target.
The monkeys were first introduced to the 3-D linear
translation of the robotic arm with the remaining degrees of
freedom (DoF), including rotation and grasping of the hand
and wrist. They were then allowed to control the remaining
DoF when they became proficient in controlling the
configuration. The most revolutionary part of the control of
the arm was that it was not completely controlled by the
monkeys with the neuroprosthetic. Instead, the autonomous
software the robot used in the calibration phase of the
experiment continued to be incorporated into the movement
of the arm during the control phase. However, this software
Neuroprosthetic Use and Training in Primates
Another trial using primates and neuroprosthetics took
place at the University of Pittsburgh; however in this
experiment, trials were focused on the control of a robotic arm
using the neuroprosthetic interface. Two monkeys were
outfitted with neuroprosthetic 96-channel chromic
intracortical microelectrode arrays to detect and interpret
brain signals into useful commands for the robotic arm. At the
time of the trial, both the monkeys had no prior experience
with brain control or BCIs [6].
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acted as a template, drastically limiting error of the
neuroprosthetic and robotic arm due to the shared nature of
the system, much like having assistance settings turned on in
a driving simulation [6]. However, as the monkeys progressed
and showed improvement through practice, the autonomous
control coefficients were incrementally reduced, allowing the
monkeys more direct and full control of the robotic arm.
This trial displayed a very simple way to calibrate and
train users’ neuroprosthetics, and tested an ingenious system
for slow integration into full neuroprosthetic to mechanical
prosthetic control. The methods displayed in this experiment
can help humans use cognitive neuroprosthetic systems more
effectively and efficiently when outfitted with the appropriate
technology.
demonstrated can be used by subjects whose limbs have been
unresponsive for extended lengths of time.
ETHICAL CONSIDERATIONS
While the technology behind cognitive neuroprosthetics
is astounding, it does not come without any ethical issues. To
ensure the safety and satisfaction of the participants without
seriously compromising the results of the research, many
problems must be addressed. Since neuroprosthetics are
currently in the developmental stage, all ethical issues
surrounding them are not known; more will arise with
continued research and use. Here, three ethical issues
regarding the use of experimental cognitive neuroprosthetics
will be discussed.
Implementation of Neuroprosthetic Systems for Human
Control of Robotic Arm
Informed Consent
This study, which took place at the University of
Pittsburgh, took the idea of the previous study a step further
and analyzed the performance of a neuroprosthetic-robotic
arm system with a human control subject. The subject was a
52-year old woman with tetraplegia and spinocerebellar
degeneration, which has caused her to lose all motor control
in her upper limbs. She was surgically implanted with a
neuroprosthetic that captured her cognitive state of mind, and
contained software that translated spikes in brain activity to
commands for the robotic arm she was to control [7].
The robotic arm she was controlling had 10 degrees of
freedom. These degrees included four orientations of the
hand, 3D translation of the hand, and 3D orientations of the
wrist. After calibration of the neuroprosthetic to effectively
interpret spikes in the brain into cognitive intentions to move
the hand, the woman was capable of controlling all 10 degrees
of freedom that the robotic arm provided [7]. The study lasted
a full 236 days, with testing and training sessions three times
a week, in which she was assigned tasks using the arm through
the neuroprosthetic such as moving physical objects and
moving individual portions of the arm to study the accuracy
and precision of the arm [7].
The trial showed that it is possible to implement
neuroprosthetics with higher degrees of freedom. However,
the subject did have difficulty physically grasping and
holding objects, which according to the study, may have been
due to the tuning of the neuroprosthetic to interpret and
recognize cognitive signals [7]. Nevertheless, this study
demonstrates the first time using human “BMI control of an
anthropomorphic prosthetic arm that includes continuous
control of multiple dimensions of hand shape,” which is a
huge advancement in the field, as it proves the usefulness of
the technology and the plausibility of more advanced systems
neuroprosthetic systems for robotic limb control in the future
[7]. The study also demonstrated a subject can still control the
neuroprosthetic device for their paralyzed limb without
having continuous experience using a normal human limb,
meaning using the neuroprosthetic and robotic arm system
The first issue, especially while neuroprosthetics are still
undergoing research and development, is informed consent of
participants in human trials. People who need
neuroprosthetics have often exhausted many other resources
without having function returned to them. It can be
challenging to determine if these people are truly informed of
and understand the risks and benefits of cognitive
neuroprosthetics, or are merely consenting out of desperation.
If someone is desperate enough, they may insist on
undergoing procedures that could potentially harm them,
ignoring the risks that the procedures could propose.
In addition, neuroprosthetics involve the implantation of
electrode arrays that directly interact with the brain.
According to
the Dr. Glannon from the University of
Calgary, this means that sometimes “cortical–limbic circuits
that are the targets of the technique are also the source of the
cognitive and affective capacities necessary for consent”, so
the procedure can alter or impair the person’s ability to give
consent [8]. While they could give consent before the
electrodes are implanted, an integral part of ethical research
is that the participant can revoke their consent at any time
during the trial. However, if the participant’s cognitive
capacity to consent is altered, this becomes impossible.
Therefore, participants in research such as this must be
ensured that they are completely aware of the risks and
benefits, including possible alterations in cognitive ability.
They should also undergo psychological evaluations to ensure
that they are in a proper state of mind to be able to consent
before they initially participate in the study.
Lack of Benefit
Another ethical issue related to consent is the knowledge
that there may be very little benefit to participating in these
research trials. Cognitive neuroprosthetics are still in the
experimental stage, so no results can be guaranteed for any
individual research participant. These limit the technology’s
potential benefits put the usefulness and value of researching
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and developing it into question. Why bother making this
technology if it barely provides any results? Telling people
that there is technology being developed that can restore their
lost senses while not being able to completely deliver on that
promise could be interpreted as lying, deceitful and unethical
to some. While there is knowledge about what results this
technology produces currently, there is uncertainty about how
long it will be until using cognitive neuroprosthetics closely
resembles typical human levels of functionality. Because of
this, it can be very challenging for research participants to see
any worth in volunteering to use a neuroprosthetic.
Many people who do volunteer for this research find
their neuroprosthetics, shortcomings and all, satisfying for
another reason. Victor Chase, a science and technology writer
for the Hastings Center, interviewed many research
participants in studies for limb neuroprosthetics, along with
other neuroprosthetics such as prosthetic eyes, and found that
“all of the patients said they had been made fully aware of the
fact that the devices they were receiving were experimental in
nature and held little if any promise of benefiting them
directly. While they obviously hoped to realize at least some
improvement in their conditions, the patients had realistic
views of the potential outcomes,” meaning that they were
aware of the risks, benefits and scarcity thereof, and were
willing to participate in these studies regardless [9]. Many of
these participants still participated in their studies because
they wanted to be able to help future generations overcome
the same challenges they are currently facing. While these
participants are being admirably altruistic, they are only doing
so because the researchers are doing their jobs of informing
them correctly, and this is not an excuse for future researchers
to take this part of their job less seriously.
may experience. It is up to the researchers who are striving to
restore this sensation and ability to these people to ensure that
they are aware of this potential harm, not to their bodies, but
to their view of themselves and psychological health.
Analysis of Ethical Issues
There are countless other ethical issues with cognitive
neuroprosthetics besides the aforementioned three. However,
there are just as many benefits that individuals may seek from
this new technology. Additionally, they may see this as their
opportunity to give back to society despite their physical
limitations. As Chase said, while reflecting upon his
interviews with research participants, many of them, “derive
satisfaction from knowing that they may be helping future
generations of people with similar maladies” [9]. While these
benefits and risks all must be considered, and properly
conveyed from researcher to participant, every participant is
responsible for their own decisions, and the only thing that
researchers can do is to inform them and respect those
decisions.
THE FUTURE OF NEUROPROSTHETICS
In the future, these ethical issues, along with other
mechanical issues that cognitive neuroprosthetics face, will
be solved. As neuroprosthetics evolve, their limitations will
gradually be eliminated and they will be safer and easier to
use. The first step towards perfecting the cognitive
neuroprosthetic is identifying any limitations, so they can be
eliminated. One limitation focuses on control of the applied
force on an object being manipulated by the prosthetic; the
device tends to not have completely lifelike precision. When
tasked with fine motor tasks, a participant must make sure that
the prosthetic hand and the object they want to manipulate are
perfectly lined up, because “any mismatch imparts forces
which will damage the robot or the object and/or displace the
target object,” whereas imparting these damage-causing
forces does not happen as easily with a biological hand [7].
That is because a human hand can sense and adjust to the
different strengths of objects it manipulates based from its
sense of touch. While cognitive neuroprosthetics do return
some sense of touch, it is not completely realistic and cannot
be interpreted properly all the time. To solve this problem,
more research can be done to produce more accurate sensation
and allow the user to consciously control the pressure they put
on an object. Additionally, this “accuracy constraint can be
relieved by a compliant effector,” so that the prosthetic itself
will automatically sense and adjust the pressure it applies to
objects to prevent damage to itself or the object [7]. As both
the effectors and the sensory input that the neuroprosthetic
provides continue to improve, this limitation will be nearly
nonexistent, and cognitive neuroprosthetics will be even more
useful.
The physical component of the neuroprosthetic is not the
only component that will continue to improve. As the BCI
Psychological Health Concerns
Many different groups of people with various
disabilities share common identities. They see themselves not
as disabled, but merely different than others. There are groups
of people who share a common disability and see it as part of
their culture, and seek strength and solidarity on others like
them. These people see themselves as part of human
neurodiversity, which is “the idea that there is natural
variation of neural and mental functions due to the interaction
of genetic, neurobiological and environmental factors” [8]. If
people who see themselves as sharing one of these common
identities with other disabled people, then they may lose this
identity if they seek treatment with cognitive
neuroprosthetics. The loss of sensation in parts of their body
is what led them to join this neurodiverse culture, but now that
these sensations are restored, their place in that culture is now
altered. The change of culture and societal placement may
have unintended psychological effects on the user during the
adjustment period of the using the prosthetic. While
neuroprosthetics can, at least from an outsider’s viewpoint,
improve the life of their user, the user must also consider if
these benefits outweigh this psychological effects that they
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advances along with cognitive neuroprosthetics, less
permanent, non-invasive BCI, which currently exist but are
not as accurate or quick as invasive BCI, could be greatly
improved upon. These non-invasive BCI use EEG to detect
and interpret the user’s thoughts. However, these signals can
suffer distortion as the signals travel through many layers of
tissue to reach the BCI. Despite this setback, “the source of
neuronal signals extracted from EEG after thorough removal
of noise, muscle, eye, and movement artifacts, are postsynaptic extracellular currents; in fact, the same currents that
contribute to spike-free LFP”, where LFP is another method
of signal detection used in invasive BCI [3]. Essentially, noninvasive BCI can detect the same information as invasive
BCI, but are slowed down due to the need to filter out
unnecessary “background noise.” If this drawback can be
eliminated, then non-invasive BCI could have similar
functionality levels as invasive BCI.
While non-invasive BCI might not be as useful for
amputees who will constantly use neuroprosthetics, they
could have alternative uses in other aspects of civilization.
Workers in nuclear power plants, mines, or other occupations
that lead to radiation exposure could perform their jobs
remotely using robots equipped with cognitive
neuroprosthetics. Other dangerous fields, such as firefighting
or search-and-rescue teams that face severe bodily harm could
also benefit from this technology. It would be more cost
effective and ethical for companies to use non-invasive BCI
instead of requiring employees to get BCI implants, and they
would be able to use the BCI with multiple employees. It
would allow people to continue working with lessened health
risks that those occupations currently present.
primary stages of testing, the cost associated with the
technology remains at a premium. Development of the
technology, as well as possible marketing, material costs, and
calibration time that goes into the prosthetic is the cause of
the high price to implement such a technology. In order to be
sustainable, the total expenses of each neuroprosthetic to be
created and correctly implemented needs to be under the total
income that the technology brings in, so that the product can
“break even.” With any product, if the expenses outweigh the
income, the product is not capable of maintaining stable
production and manufacturing. In the current state of
neuroprosthetics, the technology is not economically
sustainable since much more money is used on research and
development than the neuroprosthetic devices are bringing in.
However, this may not always be the case. Due to the
technology still being developed, neuroprosthetic devices are
produced one at a time when the need arises. Despite the high
quality and detailed customization of each device, this oneoff method is one of the most expensive ways to produce
individual products. When the technology finishes the
development stage and begins commercialization, other types
of production could be enacted such as mass customization or
batch production, each of which would drastically decrease
the production costs of the neuroprosthetic system. In
addition to more effective marketing, changes in regulation as
cognitive neuroprosthetics become more well-known, and
health care covering more of the costs for this technology,
decreases in expenses of production combined with the lack
of development costs could bring down the price of the
technology to a sustainable and marketable level.
EVALUATION OF COGNITIVE
NEUROPROSTHETICS
Market Integration
While the cognitive neuroprosthetic technology has a
high potential to solve several problems that our society faces,
it must overcome its present limitations first. For example,
neuroprosthetic device companies have had difficulties when
attempting to commercialize their devices. According to Dr.
Robert Gaunt, a cognitive neuroprosthetics researcher at the
University of Pittsburgh, the market for the device is very
small, causing marketing campaigns for the devices rather
ineffective [10]. Also, certain regulations within the United
States can restrict the use commercialized use of these
prosthetics, causing the market vary in size and availability of
products based on location. Dr. Gaunt continues, saying that
medical reimbursement also causes an issue for commercial
use [10]. Unlike more well-known medical devices,
neuroprosthetics are fairly new and are not accepted under all
insurance policies for patients needing the device to regain
functionality [10]. Each of these restrictions causes a very
high barrier when attempting to sell them to the public.
With few patients in the marketplace and capable to
purchase this technology, sustainability of the neuroprosthetic
technology needs to be questioned. Due to the complex nature
of the neuroprosthetic and the technology still being in its
The technology of neuroprosthetic devices in
combination with robotic limbs has seen drastic
improvements within recent years, and has proved the
functionality and the usability of the technology in primates
and humans alike. Testing of increasingly controllable
degrees of freedom have been successful, and the use of
tactile feedback has shown to increase functionality of the
limb by providing direct feedback from the robotic system,
much like a human arm. However, the neuroprosthetic
technology is not without ethical concerns, such as the
insurance that subjects are not only aware of the benefits that
neuroprosthetics can provide, but more importantly the risks
that being a part of a neuroprosthetic study include. Also, the
neuroprosthetic does not guarantee an improved quality of
life, so exposing people to the risks associated with the
technology without a guarantee of a benefit proves to be a
very large ethical dilemma for the use of the technology.
There also issues hindering further widespread use, as they
are expensive, face restrictive regulations, and cost cannot be
cut easily unless mass production is implemented. For further
developments in the technology to be easily created, the cost
7
Peter Gibson
Josh Tarlo
[8] W. Glannon. “Ethical Issues in Neuroprosthetics.” Journal
must first be reduced so the manufacturers, researchers, and
developers are not hemorrhaging money.
Nevertheless, although relatively new, neuroprosthetic
technology is a very promising option for patients who are
incapable of utilizing normal mechanical prosthetic systems.
As this technology continues to develop, the possibility of
neuroprosthetics being more commonplace will become
greater, providing more options for those who are paralyzed
or otherwise cannot use regular mechanical prosthetic devices
due to an injury or disability. This technology could
drastically improve the lives of thousands of people by
providing them with the opportunity to counteract a lifechanging disability.
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Trials and Human Subjects Research. 2.13.2007. Accessed
1.8.2017.
http://www.thehastingscenter.org/the-ethics-ofneural-prosthetics/.
[10] R. Gaunt. Email correspondence regarding sustainability
in prosthetics. University of Pittsburgh Rehab Neural
Engineering Lab. 3.28.2017
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ACKNOWLEDGMENTS
We would like to thank Michelle Riffitts, our conference
co-chair, for providing us with valuable feedback and
answering our questions concerning this paper. We would
also like to thank the University of Pittsburgh library for
providing us with the resources for this paper. Finally, a
special thanks to Dr. Gaunt, for giving us valuable insight into
prosthetic sustainability.
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