Blood Flow Dynamics: Understanding Vasomotion and HEG Training
Dr. Andrew Hill's recent livestream tackled a fascinating aspect of brain function that most people never consider: the rhythmic pumping of blood vessels in your brain. This wasn't just academic theory - it revealed why certain biofeedback techniques work for conditions like migraines and attention problems.
The discussion centered on vasomotion, the discovery that brain blood vessels aren't passive pipes but active oscillators that pump every 10 seconds or so. Recent 2024 research is finally explaining the mechanisms behind HEG (hemoencephalography) training, a biofeedback technique that measures brain blood flow using infrared sensors.
The Discovery: Your Brain's Hidden Rhythm
Your brain's blood vessels pulse in coordinated waves every 10 seconds - much slower than brainwaves but crucial for brain health. This phenomenon, called vasomotion, involves calcium-driven contractions in arterial smooth muscle cells that create rhythmic squeezing and relaxing patterns.
These aren't random fluctuations. The oscillations sometimes stay regional and sometimes travel as waves throughout the brain. When you're asleep, you get powerful two-hertz waves (twice per second), while the vasomotion patterns operate at 0.1 hertz (once every 10 seconds).
The system has two key drivers. First, smooth muscle cells in blood vessels contract and oscillate autonomously through calcium-driven mechanisms. Second, specialized pacemaker neurons - less than 1% of the cortex - coordinate these rhythms locally using nitric oxide and other signaling molecules.
Why Vasomotion Matters: Fuel and Waste Management
This rhythmic pumping serves two critical functions that explain why training it matters for brain health.
For metabolic fuel delivery, the oscillating vessels create dynamic pressure gradients that optimize nutrient distribution. When blood volume drops during the squeeze phase, cerebrospinal fluid flows into spaces around vessels. When vessels relax, blood returns and CSF drains, carrying away metabolic waste.
This is essentially your brain's lymphatic pumping system. The vasomotion creates the pressure changes needed to clear cellular garbage and deliver fresh resources. It's not decorative - it's load-bearing infrastructure for brain metabolism.
The Training Connection: Why HEG Works
Three 2024 papers crystallized how this relates to biofeedback training. Bragini and colleagues used two-photon imaging in awake mice to track arterial diameter changes across large cortical sections in real-time. They found vasomotion patterns are highly trainable and show something resembling long-term potentiation.
The key insight: HEG training isn't just "increasing blood flow" generically. You're specifically training the flexibility and coordination of vasomotion patterns. The training teaches vascular oscillators to respond more smoothly and sustainably to metabolic demands.
This explains the migraine connection. Migraines may involve failures of vasomotion coordination. When the rhythmic pumping systems don't work properly, you get the vascular dysfunction that contributes to migraine pathophysiology.
The Stress Connection: Burning Out the Pacemakers
Chronic stress damages the specialized nNOS pacemaker neurons that coordinate vasomotion. These neurons release nitric oxide rhythmically to create coordinated vascular dilation events. Lose these neurons to stress, and you lose both the amplitude and coordination of vasomotion.
After stroke or chronic stress, there's dampening or complete abolishment of these oscillations. The failure to orchestrate blood flow oscillations throughout the brain appears to be a significant factor in health decline and aging.
This connects to why stress management matters for brain health. You're not just managing subjective stress - you're protecting the tiny population of neurons whose job is keeping your brain's blood flow oscillating properly.
Practical Applications and Technology
Dr. Hill uses passive infrared HEG (pirHEG) rather than active infrared systems. The passive approach doesn't emit anything - it just measures heat coming off the brain that correlates with blood flow oscillations. This allows training of the vasomotion phenomena without artificial stimulation.
The training involves real-time feedback on these slow oscillations, essentially teaching your brain to coordinate its vascular pumping more effectively. Unlike EEG neurofeedback that measures electrical activity, HEG measures thermal changes reflecting cellular metabolism and blood flow.
Current technology challenges include software limitations (Bio Explorer becoming hard to access) and the need for prosumer amplifiers. Dr. Hill mentioned working on new technology solutions targeting 2026.
Notable Q&A Highlights
Question: How does this relate to other brain training approaches?
The vasomotion training complements but differs from traditional neurofeedback. While EEG trains electrical patterns, HEG trains the metabolic and vascular support systems. Both are valuable, but they target different aspects of brain function.
Question: Why focus on passive rather than active infrared?
Active systems emit infrared energy, which can influence the very phenomena you're trying to measure. Passive systems just detect naturally occurring thermal patterns, providing cleaner feedback on actual vasomotion without external interference.
Key Takeaways
- Your brain's blood vessels actively pump in 10-second cycles - this vasomotion is crucial for fuel delivery and waste clearance, not just passive blood flow
- These pumping patterns are trainable - 2024 research confirms you can improve vasomotion coordination through biofeedback, showing plasticity similar to other neural systems
- Chronic stress kills the coordination system - protecting the specialized pacemaker neurons that orchestrate vasomotion may be crucial for long-term brain health
- HEG training targets specific mechanisms - rather than vaguely "increasing blood flow," the training improves flexibility and sustainability of vascular responses to metabolic demands
- The migraine connection is becoming clearer - vasomotion failures may contribute to migraine pathophysiology, explaining why blood flow training can help with headache disorders
This research is reshaping understanding of what HEG training actually does and why it works for conditions involving vascular dysfunction in the brain.