The Functional Neurology Center: Concussion Brain Injury Minnetonka, MN.

02/05/2026

🧠🦠 CONCUSSION, THE VAGUS NERVE & THE BRAIN–GUT AXIS:
WHY SEROTONIN, INFLAMMATION & AUTONOMIC BALANCE MATTER MORE THAN YOU’VE BEEN TOLD

When someone suffers a concussion or head injury, the focus is almost always on the brain itself — headaches, dizziness, memory problems, visual strain, brain fog.

But neuroscience is becoming increasingly clear:

👉 The brain does not heal in isolation.
👉 The vagus nerve and the brain–gut axis play a critical role in concussion recovery.

A recent comprehensive review published in the International Journal of Molecular Sciences (MDPI) highlights how gut signaling, vagal pathways, serotonin, and neuroimmune responses directly influence brain health, inflammation, mood, cognition, and recovery after neurological injury.

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🔌 The Brain–Gut Axis: A Two-Way Neurological Highway

The brain–gut axis is a bidirectional communication network connecting:

• The brain and brainstem
• The autonomic nervous system
• The immune system
• The gut microbiome
• The endocrine (hormonal) system

At the center of this network sits the vagus nerve (cranial nerve X) — the primary sensory highway sending information from the gut to the brain.

💡 Up to 80–90% of vagal fibers are afferent, meaning they carry information from the body to the brain, not the other way around.

This makes the gut one of the most powerful sensory organs influencing brain function.

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🧠 What Happens to the Vagus Nerve After Concussion?

After concussion or head trauma, several things commonly occur:

🔻 Reduced vagal tone
🔻 Autonomic imbalance (sympathetic dominance / “fight-or-flight”)
🔻 Impaired heart rate variability
🔻 Increased neuroinflammation
🔻 Altered gut motility and permeability

This dysregulation can drive persistent post-concussion symptoms, including:

• Nausea and GI upset
• Anxiety and mood changes
• Poor sleep
• Fatigue
• Brain fog
• Head pressure
• Light and sound sensitivity
• Exercise intolerance

These symptoms are not psychological — they are neurophysiological.

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🦠 The Gut, Inflammation & Brain Injury

The MDPI review highlights that after brain injury:

⚠️ The gut microbiome can become disrupted
⚠️ Intestinal permeability (“leaky gut”) may increase
⚠️ Immune signaling from the gut can amplify brain inflammation

This is critical because neuroinflammation delays neural recovery and interferes with synaptic plasticity — the brain’s ability to rewire and heal.

The vagus nerve normally helps suppress excessive inflammation via what’s known as the cholinergic anti-inflammatory pathway.

When vagal signaling is impaired, inflammation can remain unchecked.

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🌟 SEROTONIN: THE MISSING LINK MOST PEOPLE DON’T KNOW ABOUT

One of the most important — and misunderstood — pieces of the brain-gut axis is serotonin.

🧬 Over 90% of serotonin is produced in the gut, not the brain.

Serotonin plays a critical role in:

• Mood regulation
• Sleep–wake cycles
• Pain modulation
• Cognitive flexibility
• Autonomic balance
• Neuroplasticity

Gut-derived serotonin communicates with the brain primarily through the vagus nerve.

After concussion:

🔻 Serotonin signaling can become dysregulated
🔻 Vagal feedback to brainstem nuclei is altered
🔻 Mood changes, anxiety, irritability, and depression may emerge
🔻 Sleep and circadian rhythms are disrupted

This is one reason many post-concussion patients experience emotional and psychological symptoms — even without a prior history.

Again: this is biology, not weakness.

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🧠 Brainstem, Vagus & Higher Brain Centers

The vagus nerve projects directly into the nucleus tractus solitarius (NTS) in the brainstem — a key hub that connects to:

• The locus coeruleus
• The raphe nuclei (serotonin centers)
• The hypothalamus
• Limbic and emotional regulation circuits

This means vagal input from the gut can directly influence:

✔️ Arousal and alertness
✔️ Stress responses
✔️ Emotional regulation
✔️ Cognitive clarity
✔️ Recovery capacity

If this system is offline, the brain struggles to regulate itself.

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🩺 Why This Matters at The Functional Neurology Center (FNC)

At FNC, we recognize that persistent concussion symptoms are often driven by network dysfunction, not structural damage alone.

That’s why our approach looks at:

🔹 Autonomic nervous system balance
🔹 Vagal tone and brainstem integration
🔹 Gut–brain signaling
🔹 Inflammatory load
🔹 Neuroplastic recovery pathways

We don’t just ask “Where does it hurt?”
We ask “Which systems are failing to communicate?”

Because restoring communication is how healing happens.

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🧠✨ The Big Takeaway

Concussion is not just a brain injury.
It is a whole-system neurological event.

The vagus nerve and brain-gut axis — especially serotonin signaling — play a central role in:

• Persistent symptoms
• Mood and emotional changes
• Cognitive recovery
• Autonomic regulation
• Long-term brain health

Understanding and addressing these pathways can be the difference between stalled recovery and meaningful healing.

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📩 If you or someone you love is struggling with lingering concussion symptoms, know this:

👉 There is more to the story
👉 There is a physiological explanation
👉 And there is hope

TheFNC.com
612 223 8590



https://www.mdpi.com/1422-0067/26/3/1160

Interaction of the Vagus Nerve and Serotonin in the Gut–Brain Axis
by Young Keun Hwang 1ORCID and Jae Sang Oh 1,2,

02/05/2026

https://youtu.be/-0jaeT69ga4?si=Ptot9XWeywGaxeLe

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

02/05/2026

https://youtu.be/oPsFoMgYcQg?si=J5BZUNRU3OXcKslH

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

02/05/2026

https://youtu.be/cNEjuoc5lCs?si=gkK3jX7D8f8tL5P7

Enjoy the videos and music that you love, upload original content and share it all with friends, family and the world on YouTube.

02/05/2026

https://open.substack.com/pub/thefncdrschmoedc/p/the-overlooked-link-between-the-neck?r=1u7zyr&utm_medium=ios&shareImageVariant=overlay

Neck pain and dizziness often seem like separate problems, but research and clinical experience tell a different story.

02/04/2026

Concussion Is a Sensory Integration Injury

After a concussion or whiplash injury, the brain is flooded with competing signals from the neck, inner ear, eyes, and trigeminal system. When those inputs don’t match, the nervous system adapts in ways that keep symptoms alive.

This sensory mismatch can drive:
• Persistent dizziness and balance problems
• Headaches, jaw pain, and facial pressure
• Light sensitivity, eye strain, and visual fatigue
• Autonomic symptoms like nausea, anxiety, and temperature dysregulation

The upper cervical spine (C0–C3) plays a critical role in proprioception and reflexive balance control. When cervical input, vestibular gravity signals, and eye movements fall out of sync, the brainstem and cerebellum are forced to reweight sensory input—often maladaptively.

At theFNC, we assess and train concussion recovery through a cervical-vestibular-visual integration model, targeting the true drivers of post-concussion symptoms rather than chasing isolated complaints.

Because real recovery happens when the systems reconnect.

TheFNC.com

02/04/2026

https://thefnc.com/research/the-fncs-unique-approach-to-treating-dysautonomia/

For Dr. Ryan Harvey, DC, DACNB, of The Functional Neurology Center, understanding and treating dysautonomia is personal. When he was growing up in Mississippi, Harvey’s athletic activities and work on his family’s farm resulted in a couple of different head injuries that required staples. By his...

02/04/2026

TheFNC.com

02/03/2026

What was the biggest misconception you had about concussion recovery?

02/03/2026

Coming Soon: fNIRS Brain Imaging at theFNC: OBELAB South Korea 🇰🇷

At The Functional Neurology Center, we’re always asking a simple question:

What is the brain actually doing when symptoms show up?

Soon, we’ll have a powerful new way to answer that.

We’re excited to announce that functional near-infrared spectroscopy (fNIRS) brain imaging is coming soon to theFNC—adding another layer of objective insight to how we evaluate and guide neurological recovery and performance.

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What is fNIRS?

fNIRS is a non-invasive, wearable brain imaging technology that measures changes in oxygenated and deoxygenated hemoglobin in the outer layers of the brain (the cortex).

In practical terms, fNIRS allows us to observe:
• Which cortical regions are activating
• How efficiently the brain is using oxygen
• How the brain responds during real-world tasks, not just at rest

This gives direct insight into neurovascular coupling—how neural activity and blood flow work together.

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Why this matters (and why it’s different)

Most conventional brain imaging is:
• Static
• Passive
• Performed lying still

But neurological symptoms rarely show up in stillness.

They appear when you:
• Think
• Stand or walk
• Turn your head
• Process visual motion
• Combine cognition with movement
• Experience autonomic or sensory load

fNIRS allows us to assess brain function while these demands are happening.

That’s where functional neurology lives.

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What fNIRS allows us to evaluate

With fNIRS, we can objectively assess:
🧠 Cortical under-activation or over-activation
🧠 Frontal lobe and executive network efficiency
🧠 Hemispheric asymmetries
🧠 Cognitive fatigue and task intolerance
🧠 Compensatory strategies under load
🧠 Changes before and after targeted rehabilitation

This helps explain symptoms like:
• Brain fog
• Cognitive exhaustion
• Poor multitasking tolerance
• Worsening dizziness with thinking or motion
• Sensory overload

Even when structural imaging appears “normal.”

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OBELAB: wearable fNIRS technology from South Korea

The system we are integrating is developed by OBELAB, a South Korea–based neurotechnology company known for advancing wearable, high-density fNIRS systems used in research, performance, and wellness settings worldwide.

Key characteristics of OBELAB’s fNIRS technology include:
• Wireless, wearable design that allows natural movement
• High-density prefrontal and cortical coverage
• Real-time monitoring of cortical oxygenation changes
• Designed for task-based assessment, mobility, and repeated measurements

This wearable approach is especially valuable in functional neurology, where movement, balance, eye movements, and cognitive load are essential parts of assessment and rehabilitation.

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Who fNIRS is especially helpful for

✔️ Post-concussion syndrome (PCS)
✔️ Long COVID & post-viral neurological syndromes
✔️ POTS & dysautonomia
✔️ Brain fog & executive dysfunction
✔️ Chronic dizziness & vestibular disorders
✔️ Migraine & sensory intolerance
✔️ Athletes optimizing recovery, performance, and return-to-play

If symptoms worsen with load, motion, or thinking, fNIRS helps us understand why.

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How fNIRS will be used at theFNC

At theFNC, fNIRS will never be used in isolation.

It will be integrated into our advanced functional neurology model alongside:
• Visual-vestibular and oculomotor testing
• Cervical proprioceptive and postural assessment
• Balance and gait challenges
• Cognitive-motor dual-tasking
• Autonomic and exertional stressors

We use data to:
✔️ Guide individualized care plans
✔️ Target underperforming or overloaded networks
✔️ Track objective change over time
✔️ Support clinical decision-making in complex cases

This is precision-guided neurology.

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Why this matters for patients

Too many people are told:

“Your tests are normal.”

Yet daily function still feels impossible.

fNIRS helps bridge the gap between subjective symptoms and objective brain data—especially in conditions where dysfunction only appears under load.

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🚧 Coming Soon

Functional brain imaging with fNIRS is launching soon at theFNC.

📍 Minnetonka, MN
📩 Follow us or message the clinic to stay updated

There is hope—for your brain.

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Please note

While fNIRS is a valuable tool for research and general wellness, only a limited number of systems—are FDA cleared.

Because the OBELAB NIRSIT system (developed in South Korea) is not FDA-cleared, it is used exclusively for fitness or general wellness purposes and is not eligible for insurance reimbursement.

02/03/2026

🌍 Global Provider-to-Provider Consultation Program

Whether you are in Europe, Africa, Asia, the Middle East, Australia, or anywhere in the world, our team collaborates directly with your provider to deliver advanced functional neurology expertise globally.

Not every patient with a complex neurological condition can travel to Minnesota.

Distance. Health limitations. Time. International barriers.

None of these should prevent someone from accessing high-level neurological thinking.

That’s why The Functional Neurology Center (theFNC) offers a Global Provider-to-Provider Consultation Program — designed to bring our team’s advanced functional neurology expertise directly to your local healthcare provider, anywhere in the world.

⚠️ This program has limited availability and accepts a restricted number of cases at any given time to maintain clinical depth and quality.

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🧠 Important Note About This Program

This program is not intended to replace our in-clinic neurological intensive programs in Minnesota.

👉 If a patient is medically and logistically able to travel, we strongly recommend participating in our in-person intensive program whenever possible.

Our on-site programs allow for:
• Comprehensive multi-day neurological assessment
• High-density, precisely sequenced rehabilitation
• Real-time system integration and progression
• Direct hands-on clinical refinement

The virtual consultation program exists specifically for those who cannot travel — not as a substitute for in-person care.

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🧠 This Is Not Telehealth as Usual

This is not a generic virtual visit.

This program is a provider-to-provider neurological consultation, where theFNC team collaborates directly with your doctor, therapist, or clinical care team.

We function as an advanced neurological think tank, supporting complex cases that have:
• Stalled
• Plateaued
• Been misunderstood
• Never fully made sense neurologically

To preserve quality and depth, consultation slots are intentionally limited.

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👤 Who This Program Is For

This program is ideal for patients who:
• Have complex or unresolved neurological symptoms
• Have seen multiple providers without clear answers
• Are unable to travel to Minnesota at this time
• Need advanced functional neurology insight layered onto existing care

Common case types include:
• Post-concussion & traumatic brain injury
• Chronic dizziness, vertigo, balance disorders
• Cervicogenic dizziness & neck–brain integration issues
• Autonomic dysfunction / dysautonomia
• Persistent headaches, migraines, brain fog
• Visual-vestibular dysfunction
• Complex, multisystem neurological cases

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🔍 How the Program Works

1️⃣ Your provider connects with our team
We meet directly with your doctor, chiropractor, PT, OT, or medical provider via secure video conference.

2️⃣ Advanced neurological case review
We analyze:
• Detailed history and symptom patterns
• Imaging, testing, and exam findings
• Vestibular, visual, cervical, autonomic, and postural drivers
• Why prior treatments may not have worked

3️⃣ Functional neurology-based guidance
Your provider receives:
• Neurological priorities and clinical insights
• Exam strategies and interpretation guidance
• Rehabilitation sequencing recommendations
• Integration strategies across brain, eyes, neck, balance, and autonomic systems

4️⃣ Your care stays local
You continue care with your trusted provider — now supported by theFNC’s advanced neurological framework.

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💡 Why This Matters

Many complex neurological cases fail not because care wasn’t attempted — but because:

• The wrong system was addressed first
• The order of rehabilitation was incorrect
• Key neurological drivers were missed
• Care wasn’t integrated across systems

This program helps providers see the full neurological picture and intervene more effectively.

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🏥 A True Extension of theFNC — Not a Replacement

Our Minnesota in-clinic programs remain the gold standard for:
• Advanced functional neurological assessment
• Multi-system integration
• Treating cases others label as “too complex”

This virtual program extends our expertise only when in-person care is not currently feasible.

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✨ There Is Hope — Even From a Distance

If you or a loved one has a complex neurological condition and traveling to Minnesota is not possible at this time, this program offers a powerful alternative:

Your provider. Our expertise. One integrated neurological plan.

📍 Available worldwide
🌍 Provider-to-provider collaboration
🧠 Limited consultation availability

If you’d like help coordinating a virtual consultation between your provider and the theFNC team, we encourage reaching out early — spots are limited.

theFNC — There Is Hope.
DC DACNB

Please email info@theFNC.com to inquire.