Background
The
field of neurotechnology has been around for nearly half a century but
has only reached maturity in the last twenty years. The advent of brain imaging
revolutionized the field, allowing researchers to directly monitor the
brain's activities during experiments. Neurotechnology has made
significant impact on society, though its presence is so commonplace
that many do not realize its ubiquity. From pharmaceutical drugs to
brain scanning, neurotechnology affects nearly all industrialized people
either directly or indirectly, be it from drugs for depression, sleep, ADD, or anti-neurotics to cancer scanning, stroke rehabilitation, and much more.
As the field's depth increases it will potentially allow society
to control and harness more of what the brain does and how it influences
lifestyles and personalities. Commonplace technologies already attempt
to do this; games like BrainAge, and programs like Fast ForWord that aim to improve brain function, are neurotechnologies.
Currently, modern science can image nearly all aspects of the
brain as well as control a degree of the function of the brain. It can
help control depression, over-activation, sleep deprivation, and many other conditions. Therapeutically it can help improve stroke victims' motor coordination, improve brain function, reduce epileptic episodes, improve patients with degenerative motor diseases (Parkinson's disease, Huntington's disease, ALS), and can even help alleviate phantom pain perception.
Advances in the field promise many new enhancements and rehabilitation
methods for patients suffering from neurological problems. The
neurotechnology revolution has given rise to the Decade of the Mind initiative, which was started in 2007. It also offers the possibility of revealing the mechanisms by which mind and consciousness emerge from the brain.
Current technologies
Live Imaging
Magnetoencephalography is a functional neuroimaging technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain, using very sensitive magnetometers. Arrays of SQUIDs
(superconducting quantum interference devices) are the most common
magnetometer. Applications of MEG include basic research into perceptual
and cognitive brain processes, localizing regions affected by pathology
before surgical removal, determining the function of various parts of
the brain, and neurofeedback.
This can be applied in a clinical setting to find locations of
abnormalities as well as in an experimental setting to simply measure
brain activity.
Magnetic resonance imaging
(MRI) is used for scanning the brain for topological and landmark
structure in the brain, but can also be used for imaging activation in
the brain.
While detail about how MRI works is reserved for the actual MRI
article, the uses of MRI are far reaching in the study of neuroscience.
It is a cornerstone technology in studying the mind, especially with the
advent of functional MRI (fMRI).
Functional MRI measures the oxygen levels in the brain upon activation
(higher oxygen content = neural activation) and allows researchers to
understand what loci are responsible for activation under a given
stimulus. This technology is a large improvement to single cell or loci
activation by means of exposing the brain and contact stimulation.
Functional MRI allows researchers to draw associative relationships
between different loci and regions of the brain and provides a large
amount of knowledge in establishing new landmarks and loci in the brain.
Computed tomography
(CT) is another technology used for scanning the brain. It has been
used since the 1970s and is another tool used by neuroscientists to
track brain structure and activation.
While many of the functions of CT scans are now done using MRI, CT can
still be used as the mode by which brain activation and brain injury are
detected. Using an X-ray, researchers can detect radioactive markers in
the brain that indicate brain activation as a tool to establish
relationships in the brain as well as detect many injuries/diseases that
can cause lasting damage to the brain such as aneurysms, degeneration,
and cancer.
Positron emission tomography
(PET) is another imaging technology that aids researchers. Instead of
using magnetic resonance or X-rays, PET scans rely on positron emitting
markers that are bound to a biologically relevant marker such as
glucose.
The more activation in the brain the more that region requires
nutrients, so higher activation appears more brightly on an image of the
brain. PET scans are becoming more frequently used by researchers
because PET scans are activated due to metabolism whereas MRI is
activated on a more physiological basis (sugar activation versus oxygen
activation).
Transcranial magnetic stimulation
Transcranial magnetic stimulation
(TMS) is essentially direct magnetic stimulation to the brain. Because
electric currents and magnetic fields are intrinsically related, by
stimulating the brain with magnetic pulses it is possible to interfere
with specific loci in the brain to produce a predictable effect.
This field of study is currently receiving a large amount of attention
due to the potential benefits that could come out of better
understanding this technology.
Transcranial magnetic movement of particles in the brain shows promise
for drug targeting and delivery as studies have demonstrated this to be
noninvasive on brain physiology.
Transcranial direct current stimulation
Transcranial direct current stimulation (tDCS) is a form of neurostimulation
which uses constant, low current delivered via electrodes placed on the
scalp. The mechanisms underlying tDCS effects are still incompletely
understood, but recent advances in neurotechnology allowing for in vivo assessment of brain electric activity during tDCS
promise to advance understanding of these mechanisms. Research into
using tDCS on healthy adults have demonstrated that tDCS can increase
cognitive performance on a variety of tasks, depending on the area of
the brain being stimulated. tDCS has been used to enhance language and
mathematical ability (though one form of tDCS was also found to inhibit
math learning), attention span, problem solving, memory, and coordination.
Cranial surface measurements
Electroencephalography
(EEG) is a method of measuring brainwave activity non-invasively. A
number of electrodes are placed around the head and scalp and electrical
signals are measured. Typically EEGs are used when dealing with sleep,
as there are characteristic wave patterns associated with different
stages of sleep.
Clinically EEGs are used to study epilepsy as well as stroke and tumor
presence in the brain. EEGs are a different method to understand the
electrical signaling in the brain during activation.
Magnetoencephalography
(MEG) is another method of measuring activity in the brain by measuring
the magnetic fields that arise from electrical currents in the brain.
The benefit to using MEG instead of EEG is that these fields are highly
localized and give rise to better understanding of how specific loci
react to stimulation or if these regions over-activate (as in epileptic
seizures).
Implant technologies
Neurodevices
are any devices used to monitor or regulate brain activity. Currently
there are a few available for clinical use as a treatment for
Parkinson's disease. The most common neurodevices are deep brain
stimulators (DBS) that are used to give electrical stimulation to areas stricken by inactivity. Parkinson's disease is known to be caused by an inactivation of the basal ganglia
(nuclei) and recently DBS has become the more preferred form of
treatment for Parkinson's disease, although current research questions
the efficiency of DBS for movement disorders.
Neuromodulation
is a relatively new field that combines the use of neurodevices and
neurochemistry. The basis of this field is that the brain can be
regulated using a number of different factors (metabolic, electrical
stimulation, physiological) and that all these can be modulated by
devices implanted in the neural network. While currently this field is
still in the researcher phase, it represents a new type of technological
integration in the field of neurotechnology. The brain is a very
sensitive organ, so in addition to researching the amazing things that
neuromodulation and implanted neural devices can produce, it is
important to research ways to create devices that elicit as few negative
responses from the body as possible. This can be done by modifying the
material surface chemistry of neural implants.
Cell therapy
Researchers
have begun looking at uses for stem cells in the brain, which recently
have been found in a few loci. A large number of studies
are being done to determine if this form of therapy could be used in a
large scale. Experiments have successfully used stem cells in the brains
of children who suffered from injuries in gestation and elderly people
with degenerative diseases in order to induce the brain to produce new
cells and to make more connections between neurons.
Pharmaceuticals
Pharmaceuticals
play a vital role in maintaining stable brain chemistry, and are the
most commonly used neurotechnology by the general public and medicine.
Drugs like sertraline, methylphenidate, and zolpidem
act as chemical modulators in the brain, and they allow for normal
activity in many people whose brains cannot act normally under
physiological conditions. While pharmaceuticals are usually not
mentioned and have their own field, the role of pharmaceuticals is
perhaps the most far-reaching and commonplace in modern society (the
focus on this article will largely ignore neuropharmaceuticals, for more
information, see neuropsychopharmacology).
Movement of magnetic particles to targeted brain regions for drug
delivery is an emerging field of study and causes no detectable circuit
damage.
Low field magnetic stimulation
Stimulation with low-intensity magnetic fields is currently under study for depression at Harvard Medical School, and has previously been explored by Bell. It has FDA
approval for treatment of depression. It is also being researched for
other applications such as autism. One issue is that no 2 brains are
alike and stimulation can cause either polarization or depolarization.
(et al.), Marino (et al.), and others.
How these help study the brain
Magnetic
resonance imaging is a vital tool in neurological research in showing
activation in the brain as well as providing a comprehensive image of
the brain being studied. While MRIs are used clinically for showing
brain size, it still has relevance in the study of brains because it can
be used to determine extent of injuries or deformation. These can have a
significant effect on personality, sense perception, memory, higher
order thinking, movement, and spatial understanding. However, current
research tends to focus more so on fMRI or real-time functional MRI (rtfMRI).
These two methods allow the scientist or the participant, respectively,
to view activation in the brain. This is incredibly vital in
understanding how a person thinks and how their brain reacts to a
person's environment, as well as understanding how the brain works under
various stressors or dysfunctions. Real-time functional MRI is a
revolutionary tool available to neurologists and neuroscientists because
patients can see how their brain reacts to stressors and can perceive
visual feedback.
CT scans are very similar to MRI in their academic use because they can
be used to image the brain upon injury, but they are more limited in
perceptual feedback.
CTs are generally used in clinical studies far more than in academic
studies, and are found far more often in a hospital than a research
facility. PET scans are also finding more relevance in academia because
they can be used to observe metabolic uptake of neurons, giving
researchers a wider perspective about neural activity in the brain for a
given condition.
Combinations of these methods can provide researchers with knowledge of
both physiological and metabolic behaviors of loci in the brain and can
be used to explain activation and deactivation of parts of the brain
under specific conditions.
Transcranial magnetic stimulation is a relatively new method of
studying how the brain functions and is used in many research labs
focused on behavioral disorders and hallucinations. What makes TMS
research so interesting in the neuroscience community is that it can
target specific regions of the brain and shut them down or activate
temporarily; thereby changing the way the brain behaves. Personality
disorders can stem from a variety of external factors, but when the
disorder stems from the circuitry of the brain TMS can be used to
deactivate the circuitry. This can give rise to a number of responses,
ranging from “normality” to something more unexpected, but current
research is based on the theory that use of TMS could radically change
treatment and perhaps act as a cure for personality disorders and
hallucinations. Currently, repetitive transcranial magnetic stimulation (rTMS)
is being researched to see if this deactivation effect can be made more
permanent in patients suffering from these disorders. Some techniques
combine TMS and another scanning method such as EEG to get additional
information about brain activity such as cortical response.
Both EEG and MEG are currently being used to study the brain's
activity under different conditions. Each uses similar principles but
allows researchers to examine individual regions of the brain, allowing
isolation and potentially specific classification of active regions. As
mentioned above, EEG is very useful in analysis of immobile patients,
typically during the sleep cycle. While there are other types of
research that utilize EEG, EEG has been fundamental in understanding the resting brain during sleep.
There are other potential uses for EEG and MEG such as charting
rehabilitation and improvement after trauma as well as testing neural
conductivity in specific regions of epileptics or patients with
personality disorders.
Neuromodulation can involve numerous technologies combined or
used independently to achieve a desired effect in the brain. Gene and
cell therapy are becoming more prevalent in research and clinical trials
and these technologies could help stunt or even reverse disease
progression in the central nervous system. Deep brain stimulation is
currently used in many patients with movement disorders and is used to
improve the quality of life in patients.
While deep brain stimulation is a method to study how the brain
functions per se, it provides both surgeons and neurologists important
information about how the brain works when certain small regions of the
basal ganglia (nuclei) are stimulated by electrical currents.
Future technologies
The
future of neurotechnologies lies in how they are fundamentally applied,
and not so much on what new versions will be developed. Current
technologies give a large amount of insight into the mind and how the
brain functions, but basic research is still needed to demonstrate the
more applied functions of these technologies. Currently, rtfMRI is being
researched as a method for pain therapy. deCharms et al. have shown
that there is a significant improvement in the way people perceive pain
if they are made aware of how their brain is functioning while in pain.
By providing direct and understandable feedback, researchers can help
patients with chronic pain decrease their symptoms. This new type of
bio/mechanical-feedback is a new development in pain therapy.
Functional MRI is also being considered for a number of more applicable
uses outside of the clinic. Research has been done on testing the
efficiency of mapping the brain in the case when someone lies as a new
way to detect lying. Along the same vein, EEG has been considered for use in lie detection as well. TMS is being used in a variety of potential therapies for patients with personality disorders, epilepsy, PTSD, migraine, and other brain-firing disorders, but has been found to have varying clinical success for each condition.
The end result of such research would be to develop a method to alter
the brain's perception and firing and train patients' brains to rewire
permanently under inhibiting conditions (for more information see rTMS). In addition, PET scans have been found to be 93% accurate in detecting Alzheimer's disease
nearly 3 years before conventional diagnosis, indicating that PET
scanning is becoming more useful in both the laboratory and the clinic.
Stem cell
technologies are always salient both in the minds of the general public
and scientists because of their large potential. Recent advances in
stem cell research have allowed researchers to ethically pursue studies
in nearly every facet of the body, which includes the brain. Research
has shown that while most of the brain does not regenerate and is
typically a very difficult environment to foster regeneration, there are portions of the brain with regenerative capabilities (specifically the hippocampus and the olfactory bulbs).
Much of the research in central nervous system regeneration is how to
overcome this poor regenerative quality of the brain. It is important to
note that there are therapies that improve cognition and increase the
amount of neural pathways,
but this does not mean that there is a proliferation of neural cells in
the brain. Rather, it is called a plastic rewiring of the brain (plastic
because it indicates malleability) and is considered a vital part of
growth. Nevertheless, many problems in patients stem from death of
neurons in the brain, and researchers in the field are striving to
produce technologies that enable regeneration in patients with stroke,
Parkinson's diseases, severe trauma, and Alzheimer's disease,
as well as many others. While still in fledgling stages of development,
researchers have recently begun making very interesting progress in
attempting to treat these diseases. Researchers have recently
successfully produced dopaminergic
neurons for transplant in patients with Parkinson's diseases with the
hopes that they will be able to move again with a more steady supply of
dopamine. Many researchers are building scaffolds that could be transplanted into a patient with spinal cord trauma to present an environment that promotes growth of axons
(portions of the cell attributed with transmission of electrical
signals) so that patients unable to move or feel might be able to do so
again.
The potentials are wide-ranging, but it is important to note that many
of these therapies are still in the laboratory phase and are slowly
being adapted in the clinic.
Some scientists remain skeptical with the development of the field, and
warn that there is a much larger chance that electrical prosthesis will
be developed to solve clinical problems such as hearing loss or
paralysis before cell therapy is used in a clinic.
Novel drug delivery systems are being researched in order to
improve the lives of those who struggle with brain disorders that might
not be treated with stem cells, modulation, or rehabilitation.
Pharmaceuticals play a very important role in society, and the brain has
a very selective barrier that prevents some drugs from going from the
blood to the brain. There are some diseases of the brain such as
meningitis that require doctors to directly inject medicine into the
spinal cord because the drug cannot cross the blood–brain barrier.
Research is being conducted to investigate new methods of targeting the
brain using the blood supply, as it is much easier to inject into the
blood than the spine. New technologies such as nanotechnology
are being researched for selective drug delivery, but these
technologies have problems as with any other. One of the major setbacks
is that when a particle is too large, the patient's liver
will take up the particle and degrade it for excretion, but if the
particle is too small there will not be enough drug in the particle to
take effect.
In addition, the size of the capillary pore is important because too
large a particle might not fit or even plug up the hole, preventing
adequate supply of the drug to the brain.
Other research is involved in integrating a protein device between the
layers to create a free-flowing gate that is unimpeded by the
limitations of the body. Another direction is receptor-mediated
transport, where receptors in the brain used to transport nutrients are
manipulated to transport drugs across the blood–brain barrier.
Some have even suggested that focused ultrasound opens the blood–brain
barrier momentarily and allows free passage of chemicals into the brain.
Ultimately the goal for drug delivery is to develop a method that
maximizes the amount of drug in the loci with as little degraded in the
blood stream as possible.
Neuromodulation is a technology currently used for patients with
movement disorders, although research is currently being done to apply
this technology to other disorders. Recently, a study was done on if DBS
could improve depression with positive results, indicating that this
technology might have potential as a therapy for multiple disorders in
the brain. DBS is limited by its high cost however, and in developing countries the availability of DBS is very limited. A new version of DBS is under investigation and has developed into the novel field, optogenetics. Optogenetics is the combination of deep brain stimulation with fiber optics
and gene therapy. Essentially, the fiber optic cables are designed to
light up under electrical stimulation, and a protein would be added to a
neuron via gene therapy to excite it under light stimuli.
So by combining these three independent fields, a surgeon could excite a
single and specific neuron in order to help treat a patient with some
disorder. Neuromodulation offers a wide degree of therapy for many
patients, but due to the nature of the disorders it is currently used to
treat its effects are often temporary. Future goals in the field hope
to alleviate that problem by increasing the years of effect until DBS
can be used for the remainder of the patient's life. Another use for
neuromodulation would be in building neuro-interface prosthetic devices
that would allow quadriplegics the ability to maneuver a cursor on a
screen with their thoughts, thereby increasing their ability to interact
with others around them. By understanding the motor cortex and
understanding how the brain signals motion, it is possible to emulate
this response on a computer screen.
Ethics
Stem cells
The
ethical debate about use of embryonic stem cells has stirred
controversy both in the United States and abroad; although more recently
these debates have lessened due to modern advances in creating induced
pluripotent stem cells from adult cells. The greatest advantage for use
of embryonic stem cells is the fact that they can differentiate (become)
nearly any type of cell provided the right conditions and signals.
However, recent advances by Shinya Yamanaka et al. have found ways to
create pluripotent cells without the use of such controversial cell
cultures.
Using the patient's own cells and re-differentiating them into the
desired cell type bypasses both possible patient rejection of the
embryonic stem cells and any ethical concerns associated with using
them, while also providing researchers a larger supply of available
cells. However, induced pluripotent cells have the potential to form
benign (though potentially malignant) tumors, and tend to have poor
survivability in vivo (in the living body) on damaged tissue.
Much of the ethics concerning use of stem cells has subsided from the
embryonic/adult stem cell debate due to its rendered moot, but now
societies find themselves debating whether or not this technology can be
ethically used. Enhancements of traits, use of animals for tissue
scaffolding, and even arguments for moral degeneration have been made
with the fears that if this technology reaches its full potential a new
paradigm shift will occur in human behavior.
Military application
New
neurotechnologies have always garnered the appeal of governments, from
lie detection technology and virtual reality to rehabilitation and
understanding the psyche. Due to the Iraq War and War on Terror,
American soldiers coming back from Iraq and Afghanistan are reported to
have percentages up to 12% with PTSD.
There are many researchers hoping to improve these peoples' conditions
by implementing new strategies for recovery. By combining
pharmaceuticals and neurotechnologies, some researchers have discovered
ways of lowering the "fear" response and theorize that it may be
applicable to PTSD.
Virtual reality is another technology that has drawn much attention in
the military. If improved, it could be possible to train soldiers how to
deal with complex situations in times of peace, in order to better
prepare and train a modern army.
Privacy
Finally, when these technologies are being developed society must
understand that these neurotechnologies could reveal the one thing that
people can always keep secret: what they are thinking. While there are
large amounts of benefits associated with these technologies, it is
necessary for scientists, citizens and policy makers alike to consider
implications for privacy.
This term is important in many ethical circles concerned with the state
and goals of progress in the field of neurotechnology (see Neuroethics).
Current improvements such as “brain fingerprinting” or lie detection
using EEG or fMRI could give rise to a set fixture of loci/emotional
relationships in the brain, although these technologies are still years
away from full application.
It is important to consider how all these neurotechnologies might
affect the future of society, and it is suggested that political,
scientific, and civil debates are heard about the implementation of
these newer technologies that potentially offer a new wealth of
once-private information.
Some ethicists are also concerned with the use of TMS and fear that the
technique could be used to alter patients in ways that are undesired by
the patient.
Cognitive liberty
Cognitive liberty
refers to a suggested right to self-determination of individuals to
control their own mental processes, cognition, and consciousness
including by the use of various neurotechnologies and psychoactive
substances. This perceived right is relevant for reformation and
development of associated laws.
