pirHEG: Training Blood Flow for Peak Brain Performance
Dr. Hill dove into passive infrared hemoencephalography (pirHEG) during this Monday evening session, addressing the growing interest in this specialized form of neurofeedback. Unlike traditional EEG training that targets brainwaves, pirHEG trains cerebral blood flowâspecifically prefrontal perfusion patterns that support executive function, concentration, and vascular health.
Two Flavors of Hemoencephalography
Near-Infrared (nirHEG) vs. Passive Infrared (pirHEG)
Dr. Hill explained the key distinction between these approaches, both co-developed around the same time. Near-infrared HEG, created by Dr. Hershel Toomim, uses active light emissionâbouncing red light off tissue to measure oxygenated versus deoxygenated blood ratios. The technology resembles consumer devices like Mendi headsets, which are readily available for a few hundred dollars.
Passive infrared takes a different approach. It uses unfocused infrared sensors positioned slightly away from the forehead, detecting heat signatures from cerebral blood flow changes. "I find that pirHEG works a lot better," Dr. Hill noted. "It tends to have more impact for the things I use it forâmigraines, brain fog from concussions, and it seems to boost social function."
The practical difference: nirHEG can target specific locations around the head, while pirHEG works exclusively on the prefrontal area in the midline. This reflects pirHEG's global, unfocused sensing approach versus nirHEG's more spatially precise measurements.
Clinical Applications and Mechanisms
Migraine Control Through Vascular Training
Dr. Hill emphasized pirHEG's effectiveness for migraine managementâboth prevention and acute intervention. "You can use pirHEG to massage away migraines, either the tendency in general or actually stop them cold if they're starting." The mechanism involves training voluntary control over neurovascular patterns, particularly the prefrontal blood flow dynamics that influence migraine triggers.
Performance Enhancement
Healthy individuals can derive significant benefits. Dr. Hill described improvements in baseball players' hitting performance and fencers' reaction times. For fencers specifically, the training enhanced their ability to maintain calm intensity during extreme physical exertionâstaying "quick and light" while controlling spatial dynamics with opponents.
The underlying mechanism targets executive function circuits. pirHEG appears to "crank up intensity of executive function and reaction time" by optimizing prefrontal perfusion patterns that support sustained attention and rapid decision-making.
Notable Q&A: When HEG Goes Wrong
Question: A viewer experienced extreme headaches and mental fatigue lasting 2-3 days after pirHEG training. What causes this reaction?
Dr. Hill identified this as likely overtrainingâtoo much metabolic demand too soon. "If it knocked you over, it was probably too much too soon for the metabolic loading." He noted that people with active inflammation from COVID, chemotherapy, mold exposure, Lyme disease, or autonomic dysfunction often can't initially tolerate pirHEG's metabolic demands.
The recommendation: wait until you can handle sauna sessions or exercise without post-exertional fatigue before attempting pirHEG. This indicates sufficient metabolic capacity to handle the vascular training load.
Question: How often should you train, and for how long?
Brief, frequent sessions work best. Dr. Hill demonstrated 5-10 minute sessions, emphasizing that pirHEG works more like peripheral biofeedback than traditional neurofeedback. The goal is direct skill transfer of vascular control rather than operant conditioning with reward thresholds.
Technical Challenges and Equipment
Dr. Hill acknowledged the accessibility issues plaguing pirHEG adoption. The specialized equipment requires specific amplifiers (like the QIS or NeurobitOptima) with auxiliary ports for thermocouple connections. Several manufacturers have been affected by supply chain issues, making equipment harder to obtain.
The pirHEG headset itself is relatively simpleâinfrared sensors in an adjustable headband positioned slightly away from the forehead skin. The challenge lies in finding compatible amplification and software systems.
Training Considerations and Contraindications
Timing Matters
pirHEG is activating, not relaxing. "You don't want to do pirHEG when you're trying to do alpha training or theta training," Dr. Hill warned. The blood flow training supports beta wave activity and awakens tissue metabolismâcontradicting relaxation-based protocols.
Medical Clearance
For individuals with stroke history, aneurysms, or vascular fragility, Dr. Hill recommends neurological clearance before training. While pirHEG is passive (no energy input), it does provide biofeedback on blood flow patterns, warranting caution in compromised vascular systems.
Key Takeaways
⢠pirHEG trains prefrontal blood flow using passive infrared detection of cerebral perfusion changes ⢠Clinical applications include migraine control, post-concussion brain fog, and executive function enhancement ⢠Brief sessions (5-10 minutes) work better than extended training periods ⢠Contraindicated during relaxation training due to its activating effects on brain metabolism ⢠Equipment accessibility remains challenging, limiting widespread adoption despite clinical effectiveness
The session highlighted pirHEG's unique position in neurofeedbackâtargeting vascular rather than electrical brain dynamics. For appropriate candidates, it offers rapid results in areas where traditional EEG training may be slower or less effective, particularly vascular-mediated conditions like migraines and perfusion-related cognitive symptoms.