A laboratory rat with a brain implant used to record neuronal activity
Brain implants, often referred to as neural implants, are technological devices that connect directly to a biological subject's brain – usually placed on the surface of the brain, or attached to the brain's cortex. A common purpose of modern brain implants and the focus of much current research is establishing a biomedical prosthesis circumventing areas in the brain that have become dysfunctional after a stroke or other head injuries. This includes sensory substitution, e.g., in vision.
Other brain implants are used in animal experiments simply to record
brain activity for scientific reasons. Some brain implants involve
creating interfaces between neural systems and computer chips. This work is part of a wider research field called brain-computer interfaces. (Brain-computer interface research also includes technology such as EEG arrays that allow interface between mind and machine but do not require direct implantation of a device.)
Neural implants such as deep brain stimulation and Vagus nerve stimulation are increasingly becoming routine for patients with Parkinson's disease and clinical depression, respectively.
Purpose
Brain implants electrically stimulate, block or record (or both record and stimulate simultaneously) signals from single neurons or groups of neurons (biological neural networks) in the brain. The blocking technique is called intra-abdominal vagal blocking.
This can only be done where the functional associations of these
neurons are approximately known. Because of the complexity of neural
processing and the lack of access to action potential related signals using neuroimaging
techniques, the application of brain implants has been seriously
limited until recent advances in neurophysiology and computer processing
power. Much research is also being done on the surface chemistry of
neural implants in effort to design products which minimize all negative
effects that an active implant can have on the brain, and that the body
can have on the function of the implant. Researchers are also exploring
a range of delivery systems, such as using veins, to deliver these
implants without brain surgery; by leaving the skull sealed shut,
patients could receive their neural implants without running as great a
risk of seizures, strokes, or permanent neural impairments, all of which
can be caused by open-brain surgery.
Research and applications
Research in sensory substitution has made significant progress since 1970. Especially in vision, due to the knowledge of the working of the visual system, eye implants (often involving some brain implants or monitoring) have been applied with demonstrated success. For hearing, cochlear implants are used to stimulate the auditory nerve directly. The vestibulocochlear nerve is part of the peripheral nervous system, but the interface is similar to that of true brain implants.
Multiple projects have demonstrated success at recording from the
brains of animals for long periods of time. As early as 1976,
researchers at the NIH led by Edward Schmidt made action potential recordings of signals from rhesus monkey motor cortexes using immovable "hatpin" electrodes,
including recording from single neurons for over 30 days, and
consistent recordings for greater than three years from the best
electrodes.
The "hatpin" electrodes were made of pure iridium and insulated with Parylene, materials that are currently used in the Cyberkinetics implementation of the Utah array.
These same electrodes, or derivations thereof using the same
biocompatible electrode materials, are currently used in visual
prosthetics laboratories, laboratories studying the neural basis of learning, and motor prosthetics approaches other than the Cyberkinetics probes.
Schematic of the "Utah" Electrode Array
Other laboratory groups produce their own implants to provide unique capabilities not available from the commercial products.
Breakthroughs include studies of the process of functional brain re-wiring throughout the learning of a sensory discrimination, control of physical devices by rat brains, monkeys over robotic arms, remote control of mechanical devices by monkeys and humans, remote control over the movements of roaches, the first reported use of the Utah Array in a human for bidirectional signalling.
Currently a number of groups are conducting preliminary motor
prosthetic implants in humans. These studies are presently limited to
several months by the longevity of the implants. The array now forms the
sensor component of the Braingate.
Much research is also being done on the surface chemistry of neural implants
in effort to design products which minimize all negative effects that
an active implant can have on the brain, and that the body can have on
the function of the implant.
Another type of neural implant that is being experimented on is Prosthetic Neuronal Memory Silicon Chips, which imitate the signal processing done by functioning neurons that allows peoples' brains to create long-term memories.
In 2016, scientists at the University of Illinois at Urbana–Champaign announced development of tiny brain sensors for use postoperative monitoring, which melt away when they are no longer needed.
In 2016, scientists out of the University of Melbourne
published proof-of-concept data related to a discovery for Stentrode, a
device implanted via the jugular vein, demonstrated the potential for a
neural recording device to be engineered onto a stent and implanted
into a blood vessel in the brain, without the need for open brain
surgery. The technology platform is being developed for patients with
paralysis to facilitate control of external devices such as robotic
limbs, computers and exoskeletons by translating brain activity. It may
ultimately help diagnose and treat a range of brain pathologies, such as
epilepsy and Parkinson’s disease.
Military
DARPA has announced its interest in developing "cyborg insects" to transmit data from sensors implanted into the insect during the pupal
stage. The insect's motion would be controlled from a
Micro-Electro-Mechanical System (MEMS) and could conceivably survey an
environment or detect explosives and gas. Similarly, DARPA is developing a neural implant to remotely control the movement of sharks.
The shark's unique senses would then be exploited to provide data
feedback in relation to enemy ship movement or underwater explosives.
In 2006, researchers at Cornell University invented a new surgical procedure to implant artificial structures into insects during their metamorphic development. The first insect cyborgs, moths with integrated electronics in their thorax, were demonstrated by the same researchers. The
initial success of the techniques has resulted in increased research
and the creation of a program called Hybrid-Insect-MEMS, HI-MEMS. Its
goal, according to DARPA's Microsystems Technology Office,
is to develop "tightly coupled machine-insect interfaces by placing
micro-mechanical systems inside the insects during the early stages of
metamorphosis".
The use of neural implants has recently been attempted, with
success, on cockroaches. Surgically applied electrodes were put on the
insect, which were remotely controlled by a human. The results, although
sometimes different, basically showed that the cockroach could be
controlled by the impulses it received through the electrodes. DARPA is now funding this research because of its obvious beneficial applications to the military and other areas.
In 2009 at the Institute of Electrical and Electronics Engineers (IEEE) Micro-electronic mechanical systems (MEMS) conference in Italy, researchers demonstrated the first "wireless" flying-beetle cyborg. Engineers at the University of California at Berkeley pioneered the design of a "remote controlled beetle", funded by the DARPA HI-MEMS Program. This was followed later that year by the demonstration of wireless control of a "lift-assisted" moth-cyborg.
Eventually researchers plan to develop HI-MEMS for dragonflies, bees, rats and pigeons. For the HI-MEMS cybernetic
bug to be considered a success, it must fly 100 metres (330 ft) from a
starting point, guided via computer into a controlled landing within 5
metres (16 ft) of a specific end point. Once landed, the cybernetic bug
must remain in place.
In 2012, DARPA provided seed funding to Dr. Thomas Oxley, a neurointerventionist at Mount Sinai Hospital
in New York City, for a technology that became known as Stentrode.
Oxley’s group in Australia was the only non-US-based funded by DARPA as
part of the Reliable Neural Interface Technology (RE-NET) program.
This technology is the first to attempt to provide neural implants
through a minimally invasive surgical procedure that does not require
cutting into the skull. That is, an electrode array built onto a
self-expanding stent, implanted into the brain via cerebral angiography.
This pathway can provide safe, easy access and capture a strong signal
for a number of indications beyond addressing paralysis, and is
currently in clinical trials in patients with severe paralysis seeking to regain the ability to communicate.
In 2015 it was reported that scientists from the Perception and Recognition Neuro-technologies Laboratory at the Southern Federal University in Rostov-on-Don suggested using rats with microchips planted in their brains to detect explosive devices.
In 2016 it was reported that American engineers are developing a
system that would transform locusts into "remote controlled explosive
detectors" with electrodes in their brains beaming information about
dangerous substances back to their operators.
Rehabilitation
Neurostimulators have been in use since 1997 to ease the symptoms of such diseases as epilepsy, Parkinson's disease, dystonia and recently depression.
Current brain implants are made from a variety of materials such as tungsten, silicon, platinum-iridium, or even stainless steel. Future brain implants may make use of more exotic materials such as nanoscale carbon fibers (nanotubes), and polycarbonate urethane.
Brain implants are also being explored by DARPA as part of the
Reliable Neural-Interface Technology (RE-NET) program launched in 2010
to directly address the need for high-performance neural interfaces to
control the dexterous functions made possible by DARPA’s advanced
prosthetic limbs. The goal is to provide high-bandwidth, intuitive
control interface for these limbs, they will not achieve their full
potential to improve quality of life for wounded troops.
Historical research
In 1870, Eduard Hitzig and Gustav Fritsch demonstrated that electrical stimulation of the brains of dogs could produce movements. Robert Bartholow
showed the same to be true for humans in 1874. By the start of the 20th
century, Fedor Krause began to systematically map human brain areas,
using patients that had undergone brain surgery.
Prominent research was conducted in the 1950s. Robert G. Heath experimented with aggressive mental patients, aiming to influence his subjects' moods through electrical stimulation.
Yale University physiologist Jose Delgado demonstrated limited control of animal and human subjects' behaviours using electronic stimulation. He invented the stimoceiver or transdermal stimulator,
a device implanted in the brain to transmit electrical impulses that
modify basic behaviours such as aggression or sensations of pleasure.
Delgado was later to write a popular book on mind control, called Physical Control of the Mind,
where he stated: "the feasibility of remote control of activities in
several species of animals has been demonstrated [...] The ultimate
objective of this research is to provide an understanding of the
mechanisms involved in the directional control of animals and to provide
practical systems suitable for human application."
In the 1950s, the CIA also funded research into mind control techniques, through programs such as MKULTRA. Perhaps because he received funding for some research through the US Office of Naval Research,
it has been suggested (but not proven) that Delgado also received
backing through the CIA. He denied this claim in a 2005 article in Scientific American
describing it only as a speculation by conspiracy-theorists. He stated
that his research was only progressively scientifically motivated to
understand how the brain works.
Recent advances in neurotechnologies and neuroimaging, along with
an increased understanding of neurocircuitry, are factors contributing
to the rapid rise in the use of neurostimulation therapies to treat an
increasingly wide range of neurologic and psychiatric disorders.
Electrical stimulation technologies are evolving after remaining fairly
stagnant for the past 30 years, moving toward potential closed-loop
therapeutic control systems with the ability to deliver stimulation with
higher spatial resolution to provide continuous customized
neuromodulation for optimal clinical outcomes.
Concerns and ethical considerations
Ethical questions raised include who are good candidates to receive
neural implants and what are good and bad uses of neural implants.
Whilst deep brain stimulation
is increasingly becoming routine for patients with Parkinson's disease,
there may be some behavioural side effects. Reports in the literature
describe the possibility of apathy, hallucinations, compulsive gambling,
hypersexuality, cognitive dysfunction, and depression. However, these
may be temporary and related to correct placement and calibration of the
stimulator and so are potentially reversible.
Some transhumanists, such as Raymond Kurzweil and Kevin Warwick, see brain implants as part of a next step for humans in progress and evolution, whereas others, especially bioconservatives, view them as unnatural, with humankind losing essential human qualities. It raises controversy similar to other forms of human enhancement. For instance, it is argued that implants would technically change people into cybernetic organisms (cyborgs). It's also expected that all research will comply to the Declaration of Helsinki.
Yet further, the usual legal duties apply such as information to the
person wearing implants and that the implants are voluntary, with (very)
few exceptions.
Other concerns involve vulnerabilities of neural implants to
cybercrime or intrusive surveillance as neural implants could be hacked,
misused or misdesigned.
Sadja states that "one's private thoughts are important to
protect" and doesn't consider it a good idea to just charge the
government or any company with protecting them. Walter Glannon, a
neuroethicist of the University of Calgary
notes that "there is a risk of the microchips being hacked by third
parties" and that "this could interfere with the user's intention to
perform actions, violate privacy by extracting information from the
chip".
