Biofeedback refers to any technique that monitors and regulates the physiological functions using instruments which can provide information on the status of physiological activities such as brain wave pattern (by EEG), heart rate, muscle tone, skin conductance, and pain perception. Using the feedback information generated from the instrument, it is possible and easier to tweak and self-regulate those parameters in an attempt to manipulate them for intended health optimization objectives. Biofeedback is used to improve health, cognition, and to diagnose and treat diseases. Almost all types of sensory modalities and many physiological data can be detected and measured by instruments:
- Electroencephalograph (EEG: measure brain waves) is to treat cognitive impairments, psychological and psychiatric disorders, migraines and generalized seizures.
- Hemoencephalography (HEG: measure relative amount of oxygenated and unoxygenated blood in the brain) is used to treat migraine and cognitive impairments.
- Electromyograph (EMG: detect electrical action potential of muscle contraction ) can be used to treat anxiety, chronic pain and a range of other medical conditions.
- Skin thermometer (measure skin temperature) can be use to treat edema, chronic pain, anxiety, and stress and other medical conditions.
- Electrodermograph (EDG: measure skin conductance) can be use to treat anxiety, stress, and hyperhidrosis.
- Photoplethysmograph (PPG: measure the relative blood flow or blood volume pulse) is for the treatment of edema, chronic pain, hypertension, and some other medical issues.
- Electrocardiogram (ECG: measure the electrical activity of the heart) is for diagnosis and treatment of heart disease, fibromyalgia, asthma and a number of other medical problems.
- Pneumograph (or respiratory strain gauge: measures relative expansion/contraction of the chest and abdomen and respiration rate) is for treatment of chronic pulmonary obstructive disorder (COPD), hypertension, panic attack and stress.
- Capnometer (or capnography: measure end-tidal carbon dioxide in expired air) is used with Pneumograph
- Rheoencephalograph (REG: measure brain blood flow) is a technique for the conscious control of brain blood flow.
Neurobiofeedback (neurofeedback or brain wave biofeedback) also called neurotherapy is the biofeedback techniques that use Electroencephalograph (EEG) to monitor brain wave activities for health improvement, diagnosis and treatment purposes, particularly the cognition improvement and mental health optimization. This can be used in any brain wave entrainment sessions (see post “Types of Brain Wave Entrainment – Brain Wave Synchronization”) to facilitate the adjustment and timing of brain wave entrainment parameters based on the feedback information provided from EEG data. HEG is also belong to the neurobiofeedback. Positive neurobiofeedback is used for generating the desired brain activity while negative neurobiofeedback is for reducing or removing the brain activity that are not desirable. One example of negative neurobiofeedback is to reduce anxiety and stress through regulating the balance between beta wave and theta wave. Positive neurobiofeedback will increase the gamma brain wave to enhance any cognitive activities requiring complex coordination of memory, abstract reasoning, language and problem solving.
Neurobiofeedback techniques have been clinically applied in the field of diagnosis and treatment of cognitive impairment diseases. This can be done by comparing the brain wave activity pattern of healthy brain with that of diseased brain. EEG patterns in Alzheimer’s brain are distinguishly different from that of healthy brain. ADHD (attention-deficit hyperreactive disorder) and MCI (mild cognitive impairments) patients also have different EEG pattern from healthy adults. This post (brain waves) describes what brain waves are associated with different brain states (either in active cognitive alertness state or in deep relaxation state). Generally speaking, the more alertness or consciousness the brain activity is, the faster the brain waves (the larger the frequency is).
The effectiveness of neurobiofeedback in ADHD treatment is inconclusive, although several studies produced positive results. EEG models (the patterns of EEG) for identifying ADHD has been proposed. The brain wave pattern of ADHD brain features too many slow theta wave (associated with deep relaxation mode) and not enough faster beta wave (associated with attention, cognitive activities or anxiety/stress). Neurofeedback, when combined with brain wave entrainment technology, is generally designed in an attempt to stimulate the ADHD brain to produce more beta wave and/or gamma wave (associated with enhanced cognitive function) if possible.
Alzheimer’s disease is the most common form of dementia – a neuro-degenerative disease that have extensive memory and cognitive impairments. EEG has been used as a tool for diagnosing AD for several decades. Mild cognition impairment (MCI) precedes Alzheimer’s disease and is the early stage of progression of Alzheimer’s disease. EEG patterns of Alzheimer’s brain (and MCI brain) showed three major differences from that of a healthy brain:
- slowing of the EEG:
Shifting of the brain wave spectrum to the lower frequencies can be observed in MCI/AD brain. MCI/AD is associated with increased power of delta (0-4 Hz) and theta bands (4- 8 Hz) and decreased power in alpha (8-12 Hz), beta (12-40 Hz) and gamma waves (30-100 Hz). If the brain produces too many theta wave relative to beta or gamma wave, there will be a corresponding decrease in reaction time, possible difficulty in memory recall, difficulty in learning new things.
- reduced complexity of EEG signal:
Studies observed that EEG of MCI and AD brain seems to be more regular than those of healthy brain with similar age. Fewer neurons interact with each other due to MCI/AD induced loss of neurons. Neural activity patterns and dynamics become simpler and more predictable.
- perturbations in EEG synchrony:
This is reflected in the decrease of coherence in fast rhythm waves. Numerous studies have reported decreased synchrony in MCI and AD brain under rest condition (the spontaneous EEG). Many different measures of synchrony have been used in the studies of EEG of Alzheimer’s brain. These quantitative measures of synchrony reported decreased magnitude and phase coherence in the EEG of MCI and AD patients. The measure is sufficiently detailed to separate depressed MCI from healthy ones with similar age. The full frequency directed transfer function (fFDTF) was significantly reduced in MCI and AD group compared to control. It was found that the parietal to frontal direction of the information flux was weaker as well, specifically for alpha and beat wave. Decreased phase synchrony was also reported. A general decrease of global field synchrony correlates with cognitive decline and AD. However, this difference in global field synchrony was not observed in patients with mild cognitive impairments. Robust difference in the spatial distribution of EEG phase synchrony were found between AD patients and healthy subjects. Some researchers also recorded EEG of MCI and AD brain when certain cognitive (working memory) tasks are involved. Relative increase of EEG synchrony can be observed during these tasks. Overall, differences in brain wave patterns of these three features can be quantitatively analyzed using sophisticated computational programs, thus enable diagnosis as earlier as possible.
Brainwave entrainment techniques (e.g. binaural beats or music modulation), combined with neurobiofeedback, have been reported to reduce the symptoms of Alzheimer’s disease. Using EEG (and MRI) neurobiofeedback, the impact of the brain wave synchronization treatment can be scientifically measured. The combined techniques aims to reduce the excess undesirable theta or delta wave and induce and stimulate the brain to generate more beta and gamma wave. One advantage of neurobiofeedback and brain wave stimulation to modify brain states is without any side effects from medication treatment. For how brainwave entrainment works on modify and optimize brain health see post “Types of Brain Wave Entrainment – Brain Wave Synchronization”.
Other medical uses of neurobiofeedback are also documented. These include migraine, mental/behavior problems (depression, anxiety, aggression, insomnia, addiction), stroke (brain damage as a consequence of blockage of blood supply) and others.