HEG (Hemoencephalography) is a specific neurofeedback technique that trains users to consciously regulate cortical blood flow. The practice is based off of the idea that with enough “neurological feedback” (provided by an HEG device) a person becomes able to consciously control an unconscious process (blood flow). Normally it would be impossible to detect whether blood flow is high or low in certain regions, but HEG neurofeedback units have been engineered to provide us with this information.
Low blood flow to a region like the prefrontal cortex is thought to be suboptimal for concentration, relaxation, and higher-order thinking. Those with deficient blood flow to this region may suffer from brain fog, emotional dysfunction, and may have a difficult time with critical thinking or problem solving. HEG is considered an effective technique for alleviating unwanted psychological impairment stemming from poor blood flow.
How does HEG neurofeedback work?
HEG neurofeedback typically entails baseline assessments (usually to measure cognitive function and/or blood flow), followed by a training phase, and inevitably follow-up assessments to determine the degree of improvement derived from training.
Baseline assessment: A couple of baseline assessments will be taken to determine a person’s current level of cognitive functioning and blood flow. These assessments provide practitioners with the ability to track a person’s improvement following the HEG training sessions. Should a person’s cognitive performance or blood flow experience no change from the HEG neurofeedback, the person will likely derive no significant benefit.
- Test of Variables of Attention (TOVA): This test is designed to assess cognitive function.
- SPECT scan: This is a type of brain scan that measures cortical blood flow.
HEG training: Individuals will then engage in HEG neurofeedback with sessions spanning up to 60 minutes (most are 30 to 50 minutes). In many cases, sessions allow for short breaks and are not considered non-stop. Sometimes it’s necessary to take a short break after working hard to increase blood flow to a certain region.
The HEG training is typically conducted 2-3 times per week, and is generally conducted by a professional. That said, there are many HEG units available for under $1000 that can be used without the aid of a practitioner. In this case, training frequency may be subject to individual variation based on preliminary progress and/or frustrations.
The training is often conducted over a span of several months to a span of several years. Some people take longer than others to learn how to regulate cortical blood flow. Others may become adept at blood flow regulation, but they continue to practice HEG to further enhance their abilities.
Biosensory feedback: The feedback provided by most HEG units is delivered in the form of a light (usually colored red). HEG devices are commonly attached to a computer and/or have a built-in sensor. This allows you to determine how long you are able to maintain blood flow in your prefrontal cortex.
When the light stays bright red, you understand that you’ve directed increased blood flow to the prefrontal cortex. When the light dims or turns off, you know that you haven’t yet mastered the ability to maintain this prefrontal blood flow. Individuals who are able to maintain blood flow are said to have “low variability,” while those with erratic changes in blood flow have “high variability.”
The goal is to learn how to keep the red light shining and attain low variability; this signifies that prefrontal blood flow has been maintained. In some cases, feedback is delivered in the form of an auditory signal in which a certain pitch signifies increased blood flow.
Follow-up assessments: The same “TOVA” test will be administered to determine whether a person’s cognitive function has improved as a result of HEG neurofeedback. To get an even better idea of improvement, a SPECT scan may be taken to measure whether blood flow has significantly increased in the targeted prefrontal regions. These follow up assessments help understand the degree of benefit derived specifically from the HEG training.
2 Types of HEG Neurofeedback
Below are two specific types of HEG neurofeedback techniques. The two most common techniques include: NIR (near infrared) and PIR (passive infrared).
1. Near Infrared (NIR) HEG
Near-infrared HEG is designed to measure changes in oxygen levels within the blood. This technique was devised by Dr. Hershel Toomim, a preeminent HEG practitioner. Near-infrared HEG emits an alternating lights on a targeted region of the brain (usually the prefrontal cortex). The lights emitted by the HEG unit include those of two wavelengths: red (660 nm) and near infrared (850 nm).
These wavelengths of light are able to fully penetrate the skull, but reflect off of blood to provide users with feedback. The two lights work in tandem with the red light (660 nm) being used as a probe, and the infrared light (850 nm) providing a comparative baseline. Near infrared HEG is based off the fact that as HbO2 (oxygenated hemoglobin) levels increase in comparison to deoxygenated hemoglobin (Hb), the cortical blood is able to scatter more of the red light (660 nm).
The infrared light (850 nm) by comparison does not scatter more when oxygen levels of the hemoglobin change. A headband-looking device is worn by a client with a built-in spectrophotometer. This spectrophotometer contains specialized photoelectric cells that are able to measure the amount of red and infrared light being reflected by cerebral blood flow in a particular area of the cortex.
Information from the spectrometer sensors are then transmitted to a computerized algorithm responsible for calculating the ratio of red to infrared light. The ratio is then translated to a visual feedback signal that allows an individual to determine whether blood flow is low or high variability. The goal is to maintain low variability, meaning blood flow is maintained in the prefrontal region.
2. Passive Infrared (PIR) HEG
Passive infrared HEG is a technique that incorporates the measurement of cortical heat and blood oxygen levels. The sensor utilized in passive infrared HEG is similar to those used in near infrared HEG, but differs in that it is able to detect light from a narrower range within the infrared spectrum. This narrower range provides information about the heat being generated by a specific region of the brain.
The only major difference between the two techniques is that this one incorporates thermoscopy – the ability to detect temperature changes. The technique was devised by Dr. Jeffrey Carmen, a New York-based psychologist. The concept behind PIR is that when temperature increases in a certain region of the brain, it is a result of metabolizing glucose for energy.
Areas of the brain that are of warmer temperature are likely metabolizing more glucose and are thus more active than other regions. Some speculate that passive infrared (PIR) is less effective than near infrared (NIR) due to the fact that it has inferior resolution and is less specific in measuring regional blood flow.
HEG Neurofeedback Research: Potential Benefits
There is relatively new promising research emerging suggesting therapeutic benefit that could be derived from HEG training. Particularly, it is thought that increasing blood flow to the prefrontal cortex (PFC) can enhance cognitive function and learning abilities. HEG has been investigated for psychological conditions (e.g. ADHD) and neurological conditions (e.g. migraines).
ADHD: It has been thought that many individuals with ADHD (attention-deficit/hyperactivity disorder) have decreased blood flow to the prefrontal cortex region, ultimately impairing their attention. Using HEG neurofeedback to train those with ADHD to increase blood flow to this region has been thought to provide varying degrees of benefit. One case study was designed to test HEG neurofeedback on an individual formally diagnosed with ADHD.
The individual had been taking Concerta (methylphenidate) 36 mg and Ritalin 5 mg. When this individual didn’t take medication, he was reported to perform poorly on attention quotient testing as measured by the IVA (integrated visual audio) performance test. This individual also had abnormalities on QEEG (quantitative electroencephalograph) readings.
HEG training was conducted for 10 sessions to increase signals and circulation within the prefrontal cortex. These sessions were administered at the FP1, FP2 ,and FPz sites for 10 minutes either once per week or twice per week. Following the 10 sessions, this individual’s QEEG had normalized and his IVA test scores significantly improved; these results were maintained 18-months later during a follow-up assessment.
It can be concluded that individuals with ADHD may benefit from HEG neurofeedback training. It may serve as a viable Adderall alternative or allow patients to lower the dosage of their current ADHD medications. Significantly more research is warranted for utilizing HEG in the treatment of attentional deficits as it has the potential to normalize brain activity, and may be effective when used as an adjunct to EEG neurofeedback for ADHD.
- Source: http://www.tandfonline.com/doi/abs/10.1300/J184v08n03_06
Autism spectrum disorders (ASD): Individuals with autism spectrum disorders (ASD) have a tough time performing in social situations and often suffer from impulsivity, attentional difficulties, and possibly obsessive behaviors. While those with autism spectrum disorders often have above-average intelligence, their blood flow and EEG patterns are abnormal, likely contributing to functional impairments. While most studies conducted among individuals with ASDs utilize EEG neurofeedback, some have investigated NIR (near infrared) and PIR (passive infrared) HEG.
A series of case studies conducted by Limsila et al. (2004) analyzed the effects of HEG neurofeedback in 180 children (ages 3 to 18) diagnosed with autism. Researchers noted that following 40 sessions of NIR-HEG at the sites FP1 and FP2, brain oxygen levels had increased by 53%. It was noted that nearly 86% of these children increased their GPA after HEG training.
Other research by Cohen in 2006 analyzed the effects of HEG on patients with autism. This was a controlled study in which 40 patients were non-randomly assigned to receive: NIR-HEG, PIR-HEG, or served as a control by being added to a “wait-list.” While all patients had already completed 20 sessions of EEG neurofeedback before HEG, significant improvement was reported.
Specifically, improvements were noted as: 42% reduction in autistic symptoms, 55% decrease in social deficits, and 90% improvement as reported by parents. Individuals had significantly improved in both neuropsychological and behavioral functioning. QEEG readings suggested that brain waves appeared to have normalized.
NIR-HEG was found to have more benefit for attention, while PIR-HEG was suggested to offer more benefit for emotional regulation and social skills. NIR-HEG differed from PIR-HEG in terms of QEEG activation and outcomes.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/19856096
Cognitive function: Some research suggests that HEG neurofeedback is capable of improving cognitive performance. Those with cognitive deficits are thought to derive benefit from HEG training, but those without sufficient benefits may find HEG training acts as a cognitive enhancer. The theory is that by increasing cerebral blood flow to the prefrontal cortex, a person will experience greater activation of that region and ultimately better performance.
A study conducted by Toomim, Mize, Kwong et al. discovered that after 10 HEG sessions for 30 minutes, individuals with neurological deficits increased their attention and decreased impulsivity. The degree of improvement among participants was evidenced by improvement in TOVA scores from baseline.
- Source: http://www.tandfonline.com/doi/abs/10.1300/J184v08n03_02
Dyslexia: A study utilized NIR (near infrared) HEG to assess blood oxygen levels among individuals (children and teens) with dyslexia. The NIR HEG measured blood oxygen levels in both the left and right prefrontal cortex. These blood oxygen levels were measured at baseline and following a 10-day course of: breathing exercises, vocal training, and writing training.
The research demonstrated that among individuals with dyslexia, NIR devices showed decreased blood oxygen levels at baseline compared to healthy controls. In other words, individuals with dyslexia have poor prefrontal oxygenation, which may contribute to dyslexic symptoms. In addition to other standard interventions, NIR HEG training may provide some benefit.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/23835976
Migraines (Headaches): There is substantial evidence to suggest that HEG training could alleviate migraines. In one study from 2010, a total of 37 migraine sufferers were exposed to 40 neurofeedback (HEG & EEG) sessions in conjunction with thermal (hand-warming) biofeedback. All individuals were taking at least one pharmaceutical drug to treat their migraines and were instructed to maintain a journal to document the severity of their headaches.
This study specifically incorporated passive infrared (PIR) HEG. A movie played on a screen, but stopped when thermal temperature dropped as indicated by the PIR device. The goal was for the individuals to increase their forehead temperature by calmly concentrating. The PIR-HEG was show to significantly help migraine patients.
Results indicated that 26 of the 37 patients felt 50% reduction in the frequency of their headaches. This reduction was maintained for nearly 15 months after the neurofeedback training. Other evidence for PIRs efficacy in treating migraines is derived from a study documenting 100 individuals with chronic migraines; 90% of these individuals experienced significant improvements.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/20205867
- Source: http://www.tandfonline.com/doi/abs/10.1300/J184v08n03_03
Stress: It is well known that individuals with high levels of stress have reduced blood flow to the prefrontal cortex. It is possible that HEG neurofeedback training may increase a person’s ability to control and manage their stress response. While no formal research has been conducted to suggest that HEG training reduces stress, it is logical to suspect that learning to consciously increase prefrontal blood flow may reduce stress.
Advantages of HEG Neurofeedback
There are several advantages associated with using HEG neurofeedback over other methods like EEG neurofeedback.
- Accuracy: The accuracy of HEG is considered superior to that of EEG due to the fact that there’s reduced likelihood of external interference. Having a metal object in the area or other electrical signal may disrupt the results of an EEG, whereas they won’t disrupt an HEG.
- Cost: The cost of HEG neurofeedback may be appealing over the cost of EEG neurofeedback. Most HEG units can be attained for under $1000, making them a bargain compared to the money for an EEG neurofeedback unit.
- Interpretation: It is relatively easy to interpret the “feedback” signal from HEG compared to EEG. This is due to the fact that the signal is stable the entire time and you’re only dealing with a single variable.
- Less side effects: Those engaged in EEG neurofeedback run the risk of training the wrong frequencies in certain regions. Poor training without the use of a QEEG can result in performance deficits and possible neurofeedback side effects. HEG neurofeedback by comparison is safer and unlikely to impede performance or result in any side effects.
- Non-Invasive: HEG neurofeedback involves wearing a headband-like device and is non-invasive. You don’t need to take any pharmaceutical pills, or sever open the skull to collect information. The feedback signal is attained from light frequencies capable of penetrating the skull.
- Self-training: The beauty of HEG neurofeedback is that it’s so straightforward that you can conduct training sessions yourself. While working with an expert practitioner is always preferred, it’s much tougher for something to go wrong during self-HEG training compared to EEG training.
- Simplicity: Most HEG units are small, easy to set up, and training sessions can be performed in the comfort of your own home.
Disadvantages of HEG Neurofeedback
Below are some potential disadvantages associated with HEG neurofeedback.
- Blood flow: Some would argue that measuring blood flow or blood oxygenation doesn’t really tell much of anything about neurological functioning. It could be argued that training yourself to increase blood flow is a useless endeavor.
- Comparison difficulties: Due to the fact that everyone has a different skull thickness and variations in cerebral blood flow, it is difficult to compare one person’s blood flow to that of another. This makes research difficult using HEG and makes it difficult to find specific patterns among those with psychiatric conditions.
- Interference: The hair can interfere with the sensor of HEG devices, skewing results. Training must be conducted on a bald spot of the head (i.e. the forehead sites). An EEG neurofeedback unit can be used over the hair and still attain valid signals.
- Lack of evidence: There is a general lacking of research to support the efficacy of HEG neurofeedback. Most research has been conducted by Toomim (a founder of NIR-HEG), making it subject to possible biases and skewed results. Significantly more research is necessary before any definitive claims can be made to suggest that HEG can provide therapeutic benefit.
- Not instantaneous: The results from HEG training are not instantaneous and therefore research cannot utilize an HEG device to study temporal effects.
- Single “site”: HEG is only capable of training one specific “site” of the brain at a time. EEG training can target multiple sites simultaneously (and up to 19 sites in total).
Is HEG neurofeedback safe and effective?
HEG neurofeedback is considered completely safe – there’s no major health risks associated with the technique. It is non-invasive and simply measures blood flow (usually to the prefrontal cortex), allowing an individual to learn how to consciously regulate this blood flow. The technique does not involve strategically training an individual to manipulate their brain waves; which inherently carries risk of suboptimal training.
The efficacy of HEG neurofeedback is largely unknown. This technology hasn’t been used much in the realm of scientific research due to the fact that it’s difficult to compare results from one person to those of another. A majority of current research is limited to case studies, small sample sizes, and poor study designs.
This doesn’t mean that HEG is ineffective, rather it suggests that its efficacy hasn’t been thoroughly investigated in large scale studies. Perhaps the most therapeutic benefit from HEG can be attained from: those with migraines, autism spectrum disorders (ASDs), and/or ADHD.
What’s the difference between HEG and EEG neurofeedback?
The primary difference between HEG and EEG neurofeedback is that HEG trains users to consciously regulate blood flow, whereas EEG trains users to regulate brain waves. Blood flow and brain waves are entirely different neurological processes. HEG should be considered safer than EEG neurofeedback due to the fact that there is no “optimal” EEG protocol and suboptimal training may actually impair performance rather than enhance it.
HEG neurofeedback solely helps users increase blood flow to the prefrontal cortex. Increasing blood flow to the prefrontal cortex is thought to be helpful for cognitive enhancement. Furthermore, there are no notable adverse effects associated with HEG training; at the very worst there is no substantial effect or the effects are benign.
Have you tried HEG neurofeedback?
If you’ve had an experience using HEG neurofeedback to regulate cortical blood flow, be sure to leave a comment detailing your experience. Mention how many sessions it took for you to get a grasp on how to consciously increase blood flow to certain regions (e.g. prefrontal cortex). Also note why you were using HEG neurofeedback (e.g. to enhance cognition) and whether you experienced significant therapeutic effect.