The Power of Brain-Computer Interfaces in Neurorehabilitation
The idea of controlling external devices with just your mind has become possible through the use of Brain-Computer Interfaces (BCIs).
BCIs allow brain signals to direct external activity in things like prosthetics, wheelchairs, and even word-processing programs. They can do all of this because of your neurons.
Whenever you do something, your neurons work. This work is carried out by electrical impulses (brainwaves). Scientists can detect these signals, interpret them, and then translate them into commands.
How do you detect brainwaves?
There’s a variety of ways scientists are able to detect brain waves, including invasive and non-invasive methods. Most commonly, electroencephalograms (EEGs) are used to identify these impulses.
EEGs have small electrodes and wires attached to a cap. The electrodes are attached in an International 10–20 System. This system uses two reference points — the nasion and inion to define each electrode location on the scalp. This system is based on a relationship between the location of an electrode and the underlying cerebral cortex.
The electrodes in the EEG cap detect electrical impulses, amplify the signals, and record them in a wave pattern. EEGs are known to have an excellent temporal resolution, but generally, have a low spatial resolution.
Different types of brainwaves
Your brain has five different types of brainwaves, which all represent very distinct things. These brainwaves are represented in Hertz (Hz).
- Delta Waves (.5 to 3 Hz)
Low frequency and deeply penetrating, occurring in deep meditation and dreamless sleep)
- Theta Waves (3 to 8 Hz)
Great amplitude, slow frequency, they’re known to be the gateway to learning, memory, and intuition (in dream; information beyond normal conscious)
- Alpha Waves (8 to 12 Hz)
Resting state of the brain, they aid in mental coordination, calmness, alertness, mind and body integration
- Beta Waves (12 to 38 Hz)
Normal waking state of consciousness, correlate with fast activity (alert, attentive, judgment, decision-making, focused mental activity)
- Gamma Waves (38 to 42 Hz)
Fastest brainwave, high frequency, responsible for cognitive functioning (learning, memory, information processing)
Using brainwaves, BCI’s can assist in prosthetic rehabilitation, but they also have the potential of aiding in neurorehabilitation.
What is Neurorehabilitation?
Neuorehabilitation is a rehabilitation treatment designed for people with diseases, injuries, or disorders in the nervous system. The goal is to ultimately improve function, reduce symptoms, and improve patient wellbeing.
Conditions that require neurorehabilitation
- Vascular disorders (hemorrhagic strokes, transient ischemic attacks)
- Infections (meningitis, encephalitis, brain abscesses)
- Structural and neuromuscular disorders (bell palsy, cervical spondylosis, brain or spinal cord tumours)
- Functional disorders (headaches, seizures, dizziness)
- Degenerative disorders (Parkinson’s disease, multiple sclerosis, ALS, Alzheimer’s disease, Huntington chorea)
The outcomes of neurorehabilitation vary based on a variety of factors. These factors include the type of neurosurgical procedure used, the location of the brain involved, and motor, sensory, cognitive, and functional deficits associated with the surgery.
Many researchers believe that neurorehabilitation isn’t done on time. Patients usually spend their early weeks of their recovery process being treated in neurology wards, while rehab doesn’t begin until discharge.
We’re failing to optimize input in the crucial period of recovery.
Our Approach to Neurorehabilitation Today
Currently, we have five main treatments used to rehabilitate motor and cognitive recovery.
1. Constraint-induced movement therapy (CIMT)
CIMT is a type of translational neurorehabiltiation, which requires intensive, experience-based, repetitive motor training. Theoretically, it’s appealing since CIMT provides massed practice of functional movement in paretic limbs.
For example, if someone has a stroke, which leads to paralysis in their arm, it creates difficulty in daily life (bathing, dressing, eating). In CIMT, the unaffected limb is restrained by an armrest or glove so it can’t be used, while the affected arm is forced to be used instead.
CIMT has the potential to improve motor functions in neurological disorders, including cerebral palsy. The use of the paretic limb can lead to activity being seen in the primary motor cortex, premotor cortex, cerebellum, and other motor outflow areas of the brain.
Except, CIMT isn’t very practical. The time frame for the therapy is very long, while the goal of healthcare is to constrict the amount of time needed for treatment. Also, factors including, inconsistency and the high cost play into the ineffectiveness of CIMT based treatments.
2. Constraint-induced language therapy (CILT)
CILT takes a similar approach to CIMT. CILT is known to help with neurological diseases affecting speech (Parkinson’s disease). In CILT, the goal is to avoid using strategies including gesturing, drawing, and writing, instead, communicating by talking only.
CILT requires massed practice, so therapy occurs 2–4 hours every day for an extended period of time.
CILT has limited in the field of neurorehabilitation. There’s also a lack of evidence demonstrating why its superior to other aphasia therapies. The idea of “constraint” needs to be further explored by researchers, but if this therapy is implemented with social interaction, patients may gain more benefits.
3. Prism adaption training for spatial neglect
Spatial neglect is a failure to respond to contralesional stimuli (multiple stimuli of the same type), along with functional disability. Spatial neglect is found to increase hospital morbidity and affects around 50% of the 795,000 people per year who survive stroke in the USA.
The goal of this therapy is to train visual perception through verbal strategies that stroke survivors must consciously implement.
Other strategies use goal-driven strategies to increase visual perception—intended for self-implementation. This includes training of visual awareness, therapist-coached use of mental imagery, and a review of video tapped task performance with a therapist.
The use of prism adaption training is found to be impractical for patients. It’s extremely time consuming. In initial trials demonstrating visual scanning benefits, patients spent 1 hour daily on training alone, for four consecutive weeks.
4. Transcranial magnetic stimulation (TMS)
Transcranial magnetic stimulation is a non-invasive method where repetitive magnetic pulses stimulate nerve cells in the brain. This stimulation is used to help treat chronic depression.
This therapy requires an electromagnetic coil being placed against the scalp near the forehead. The coil stimulates nerve cells in the region of the brain involved in mood control and depression.
The side effects caused by transcranial magnetic stimulation are usually minor, such as headaches, scalp discomfort, spasms of facial muscles, and lightheadedness. Serious side effects include seizures, mania (generally affecting people with bipolar disorder), and hearing loss.
5. Transcranial direct current stimulation (tDCS)
TDCS is similar to TMS. It’s also a non-invasive device used to improve cognitive functions (memory, language, attention). With tDCS, direct electrical currents are used to stimulate specific parts of the brain.
There are two types of stimulation in tDCS, anodal and cathodal. Anodal stimulation is used to excite neuronal activity, while cathodal stimulation inhibits or reduces neuronal activity. TDCS has the ability to modulate differently in each hemisphere, which is useful for motor dysfunction after stroke.
TDCS is cheap, non-invasive, and painless, but it isn’t an FDA approved treatment.
How can BCI’s be a part of the Solution?
BCI’s can be considered rehabilitation devices as technological tools or in clinical settings.
As rehabilitation tools, BCI’s allow those who are disabled to operate without requiring muscular activation. BCI’s can help recover some of their lost ability because the brain has cortical plasticity. Cortical plasticity is the ability for the brain to reorganize itself by forming new connections based on individual experiences.
In clinical settings, BCI’s can provide biofeedback from controlling and modulating brain signals, or they can control external devices and provide sensory input to help normalize motor control.
Learning processes activated by both cognitive and sensory experiences related to feedback from the environment and strategies are key elements for promoting cortical plasticity. Though the brain is damaged, it triggers a reorganization of its structure.
The Jackson et al model states that three elements contribute to the rehabilitative outcome: physical execution (musculo-skeletal activity), declarative processes (information about the skill the patient has to learn), and non conscious processes (elements of skill which can’t be explicitly verbalized).
The outcome of neurorehabilitation improves with physical execution, but it’s not always a possibility for patients with brain damage.
BCI’s are able to produce motor imagery — a mental execution of a movement without any muscle activation. This can be done through the use of your electrical impulses.
Motor imagery can help with diseases such as Parkinson’s. BCI’s provide patients with feedback related to their cognitive activity, and quantitative evaluation of their engagement and ability to accomplish the task, leading to more effective treatment.
Researchers are beginning to realize that patients should be trained using BCI’s early so that they can learn necessary cognitive skills before their disease becomes too advanced.
We’re at a stage in healthcare where BCI’s have the potential of helping increase the success of neurorehabilitation.
- BCIs use brainwaves to direct external activity in things such as prosthetics
- Brainwaves are most commonly detected using electroencephalograms (EEGs)
- There are five different types of brainwaves (Delta, Theta, Alpha, Beta, Gamma)
- Neurorehabilitation is designed for people who need treatment for conditions in their nervous system
- BCI’s can help recover lost ability using biofeedback and sensory input
- BCI’s allow for motor imagery which can aid those who lack musculo-skeletal activity