pIR HEG (Passive Infrared Hemoencephalography)

It is a technology that is applied to the surface of the forehead to detect infrared thermal energy that is released from the brain. In a sense, this infrared energy can be seen as thermal waste. That is, the brain does a good job of maintaining a stable temperature in its environment. With metabolic activity in the brain, infrared energy is created and then released and this can be picked up by the pIR HEG sensor sitting atop your forehead.

To best understand why we use pIR HEG, it is important to understand the components involved.

The closest part of the brain to the pIR HEG sensor is the frontal lobe. The frontal lobe is important in activities like attention, memory, social awareness, character, motivation and planning. The frontal lobe is also involved in many brain networks that regulate brain activity and, in turn, human functions. If we increase the metabolic activity in the frontal lobe, this will be reflected as increased infrared energy released by the brain/increased signal in the pIR HEG sensor. Therefore, this can be measured and then displayed on the screen for patients to observe. This is the main principle of biofeedback: using biometric information from sensors to better understand neurological processes that play a hand in health conditions; if you can learn to control the neurological processes (as measured by the sensors) you can change the health condition’s outcome/experience.

To learn to control these neurological processes, a spirit of mindfulness goes a long way. To be successful, patients will learn to correlate what they see on the screen (about their brain’s frontal lobe metabolic activity) with subtle internal sensations. With mastery, these subtle internal sensations can be influenced (e.g., turned up or down) to change one’s physiology and improve performance.

pIR HEG was specifically invented by Dr. Jeffrey Carmen to treat migraine headaches. Since then, it has also been used in depression and ADHD.

pIR HEG is often used to encourage patients to do a few things:

  1. Increase the dominance of the frontal lobes of the brain. The frontal lobe dominance will imply that the frontal lobe will be more effective at doing what it is designed to do (see above). This will often be noted in things like improved sustained attention.
  2. Increase one’s mental agility. For example, say negative emotions are experienced because the brain’s limbic system has taken over the reins from the frontal lobe, the patient will experience decreased frontal lobe efficiency (i.e., attention, memory, planning, etc.). To learn how to soften the limbic system’s grip on those reins and give those reins back to the frontal lobe will help regulate one’s emotions.
  3. Decrease mental effort required to do a task. At first, concentrating or trying to increase frontal lobe metabolic activity can seem challenging and many do it inefficiently. With practice, it can get easier and more efficient.

The headband is applied and the software is turned on. Patients watch a movie that is emotionally gripping. The patient has to be sincere and not try to be impervious to the movie’s plot. Imagine your child not reacting at all to when little red riding hood finds the wolf in her grandmother’s place…that wouldn’t be natural. Once the emotional centers of your brain get moved by the movie, the movie pauses. You then try to regain control of your emotions by increasing your “focus” in a relaxed manner; frustration is the kryptonite to progress here. A meter will show you how you are doing so that you can gauge your effort and its result. Once you hit a certain threshold, the movie starts. And this simple process continues. Really, you are working when the movie is on pause and you are trying to get it to start up again. This amount of time is like a work out. Many concussion patients can’t tolerate too much of this work out; often 3-4 minutes is enough.

Occasionally, right after the first session or two, if people train a bit too much, people can feel tired. They may have difficulty staying on task. They may be irritable or get a headache. Usually after a good night’s sleep, they recover. The lack of other documented side effects is felt to be due to the following:

  1. pIR HEG doesn’t transfer any energy to your brain. It just reflects the amount of energy you are making with your own brain and influences your ability to increase focus with your brain’s frontal lobes or switch from other areas of your brain (i.e., limbic system) back to your frontal lobe.
  2. Increased frontal lobe dominance increases the brain’s capacity for inhibition. Although inhibition sounds like a negative word to many, the brain maintains itself between a state of over-activity and under-activity fairly well. This is largely due to the brains ability to inhibit bioelectrical circuits from running amuck. That is, the brain intrinsically has a propensity to over excite and relies on brain networks to prevent this. Many of these inhibitory networks involve the frontal lobe and so improved capacity for inhibition is considered desirable.

It is challenging to study biofeedback performance using a randomized control trial (RCT) design. RCT states that you take 2 groups of patients, alike in every way, and you only change one variable between the 2 groups.

For example:

• group 1 gets a sugar pill, also known as placebo – not expected to have any clinical effect on one’s health;

• group 2 gets the experimental drug/intervention – the one that is thought to have a beneficial effect on one’s health, but the investigators are not quite sure if it works, which is why they are doing the study.

The placebo effect is the same between both groups because both groups take a pill. Nobody knows which pill they took, not even the investigators. Therefore, if patients in group 1 believe they will get better because they took ‘a pill’, this belief will affect group 2 equally as they also took the pill. Therefore, people can’t say that group 1 ONLY got better because they took a pill –  i.e., they believed it would help them and so their nervous system’s response to this optimism improved their health – rather than being due to a positive effect by medication. The act of taking a pill will usually create faith, hope or belief in the treatment. This faith created by taking the pill will be the same between the two groups. so any differences in outcomes seen between the two groups is either due to the difference in medications (sugar pill vs. the experimental drug) or chance.

That’s right, in a RCT, any differences in outcomes between the groups could happen just because of chance. Using statistics, the likelihood of both groups’ outcomes to be due to chance is assessed. If it is really unlikely that any differences between the 2 groups is due to chance, then it is said to be due to the medication. For example, you can flip a coin 50 times in a row and possibly get heads every time, it’s possible, but it’s unlikely that that would happen by chance, so we might presume that you’re really good at flipping a coin so it shows up with heads (of course, assuming it’s not a double-sided coin).

For pIR HEG, and for biofeedback and behavioural interventions in general, it is not possible to get one group to do real pIR HEG and get another group to train with “fake” pIR HEG. You can’t create  “fake” pIR HEG, it would be like tricking people into thinking they are exercising when they are not actually exercising. The sugar pill option doesn’t exist here and so there is no way you can control for the placebo effect. Hooking yourself up to this technology and training will also stimulate faith and may set into motion natural neurological processes that will help you heal in and of itself. So, most studies on the topic have been series of case reports and quasi-experimental study designs, commonly employed in studying modalities where creating a true placebo is not possible.

The strongest evidence to pIR HEG’s utility is experiential. The inventor and psychologist Dr. Jeff Carmen has dedicated 30 years to treating tens of thousands of patients with this technology with favourable results as published in the Journal of Neurotherapy. Many others have reported similar benefit of pIR HEG in the treatment of migraine.

Neuroscience is rapidly growing. Much still has to be discovered about the pathophysiology of a migraine. Only recently has the migraine world seen the first class of preventative medication that was actually intentionally designed for migraine. This was achieved by discovering the role CGRP played in migraine genesis and checking that. Up until then, preventative drugs designed for other indications (e.g., hypertension, seizure disorders, depression, neuropathic pain, etc.) were serendipitously found to be sort of helpful in some migraine patients. That being said, there is a paucity of data to claim pIR HEG helps with other indications but experientially and theoretically, it makes sense that benefits of pIR HEG would follow from the processes it trains (see above How does pIR HEG work in improving these conditions?).

pIR HEG technology is developed and sold by many large biofeedback companies that produce technology to train elite performers like the military and high-level athletes.

Carmen, J. A. (2004). Passive infrared hemoencephalography: Four years and 100 migraines. Journal of Neurotherapy, 8 (3), 23-51. (Available here)

Walker, A. K., & Lyle, R. R. (2016). Passive Infrared Hemoencephalography (pIR HEG) for the Treatment of Migraine Without Aura. NeuroRegulation, 3(2), 78–91. (Available here)

Toomim, H., Carmen, J. (1999). Hemoencephalography (HEG). Biofeedback, 27 (4), 10-14, 27.

Stop My Migraine!

Research & writing: Dr. Taher Chugh & Mojtaba Garshasb

Last Updated: May 2019