“A Lab in a Mouse”: How Brain Gauge Lets Us Measure (and Train) Brain Fitness

When you’re testing with Brain Gauge, you’re getting an accurate assessment of what’s called functional connectivity—how well things in your brain are connected. And when those connections get weak, the scores do poorly.

But here’s the empowering part: you can do exercises to strengthen those connections.

Because just like our physical body—when we get out of shape, we go to the gym and build muscle strength—the brain is no different.

That’s the heartbeat of today’s conversation.

Welcome back to the Rethink Aging podcast

Hi there. Welcome back to the Rethink Aging Podcast.

I’m Dr. Cindy Libert, and I’m so excited to be joined by Dr. Mark Tommerdahl, PhD—neuroscientist, researcher, and founder of Brain Gauge.

We’re implementing this new technology in our practice, and I’ve been looking forward to sharing it with you because it’s both:

• a cognitive assessment tool (a way to measure brain function with surprising precision), and
• a brain training tool (a way to actually improve what we measure).

Mark, thank you so much for being here and generously giving your time.

What is Brain Gauge?

Let me paint a picture.

Brain Gauge looks like a computer mouse. But it is not a mouse.

I told Mark, “This looks like a mouse, but it is very, very sophisticated technology that’s been miniaturized.”

And Mark said it perfectly: “It is a lab in a mouse.”

He explained that what used to require a million-dollar lab setup—large, heavy, expensive equipment—has essentially been shrunk down into something the size of a computer mouse.

“It’s actually lost about 100 pounds in 20 years,” he joked.

And that miniaturization matters, because it makes something that used to be limited to research labs accessible in real clinical practice—and even at home for training.

Dr. Mark’s path to Brain Gauge (and why this became personal)

One of the reasons I loved this conversation is because Mark’s journey wasn’t just academic—it became personal.

He shared his background: biology at Davidson College, then graduate work at the University of North Carolina—but he didn’t stop there.

He told us that even early on, he felt biology wasn’t using technology as well as it could. So he pursued biomedical engineering and mathematics so he could bring cutting-edge tools into brain science.

And then he said something that stopped me in my tracks:

After about 20 years of studying the brain in the lab, he started having neurological symptoms himself.

“I started evaluating myself and testing myself and I figured out, ‘Oh, I’ve got MS,’ and I was going downhill pretty fast.”

As a researcher, he did what researchers do: he researched it exhaustively, found strategies that helped—then faced the next question:

How do you track whether you’re getting better?

And that question helped shape the direction of Brain Gauge.

How can fingertip vibrations tell us about brain function?

This is where I paused him (because Mark is passionate, and he can go deep—which I love).

I asked: How does a mouse-like device that delivers tiny vibrations to the fingertips give us a window into cortical brain function?

Mark broke it down beautifully in layman’s terms:

• Brain Gauge vibrates the index finger and middle finger (digit 2 and digit 3).
• Those fingers map to brain regions that sit side-by-side in the sensory cortex.
• The vibrations trigger activity in those brain areas and force them to “talk” to each other.
• Then the test asks very simple questions like:
  
  • “Which vibration was bigger?”
  • “Which lasted longer?”
  • “Which came first?”

And the genius is in the structure: it starts easy and gets progressively harder—like an eye chart—until it finds your precise threshold.

Mark emphasized that sensory testing like this can be extremely accurate—sometimes more sensitive than imaging for functional change.

So what you end up with is not just “how you feel your brain is doing,” or a questionnaire. It’s a performance-based measure—like testing your fitness by walking stairs or lifting weights.

That’s why we keep calling it what it is:

Brain Gauge is a brain fitness test.

What does it measure?

Mark described a “standard battery” that takes around 15 minutes and gives multiple metrics—things like:

• speed
• focus
• accuracy
• neuroplasticity
• and an overall “brain health score”

And what I love here is that these metrics aren’t just abstract numbers—Mark explained that different patterns can show up depending on what’s happening.

For example, with a concussion:

• some measures may look okay initially,
• some look terrible,
• some improve quickly,
• and some worsen later (especially as inflammation kicks in 2–3 days after a head injury).

This is part of what makes it clinically useful: it can help us track changes over time rather than relying on a single snapshot.

“We haven’t met one that Brain Gauge wasn’t sensitive to.”

Mark shared something that stood out to me as a clinician: Brain Gauge can detect changes from everything from concussion to neurodegenerative processes—and even things as simple as taking an over-the-counter cold medicine.

He explained they studied a class of drugs that affect plasticity, and while strong versions (like ketamine) aren’t used in typical human testing, they looked at a milder cousin:

dextromethorphan (found in many cough syrups).

“If you’ve ever taken cough syrup and it made you feel loopy,” he said, “that’s what we’re measuring.”

I appreciate this because it illustrates how sensitive the tool is.

How clinicians are using it in practice

Since we’re just getting started implementing Brain Gauge in our clinic, I asked Mark what other clinicians are doing.

He described a common approach:

1. Full 15-minute baseline test at the beginning of care
2. Follow-up testing to track progress over time
3. A “Quick Check” option: a 90-second test that functions almost like a vital sign
   
   • Some clinics run it every time a patient walks in
   • Sometimes they do it before and after a treatment session

And then there’s a piece I really want you to hear:

Mark compared certain treatments to “sports massage” for the brain—something that helps “loosen things up”—and then patients often do brain training immediately after to strengthen connections while the system is primed.

That’s when he brought us back to the core concept:

“When you’re testing with a brain gauge, you’re getting an accurate assessment of functional connectivity… and when those connections get weak, the scores do poorly. But you can also do exercises to strengthen those connections.”

And I jumped in because this is a key point for my patients:

This isn’t only diagnostic. It can be therapeutic.

It took me a little time to wrap my head around that, but it makes sense:

You can train the brain the way you train the body.

How often should you do brain training?

People always want a clear answer here, and Mark gave one I love because it’s practical and realistic.

He said: think in parallel with physical fitness.

• Twice a week is kind of a minimum.
• Three times a week is where you see a big difference.
• Even 20 minutes a day, three days a week, can be meaningful.

So yes—we’re adding brain training to our self-care list for keeping our brains fit as we age.

What about mild cognitive impairment and dementia?

I asked Mark specifically about neurodegenerative processes like Alzheimer’s and mild cognitive impairment.

He said Brain Gauge can pick up mild cognitive impairment, and clinicians are using brain training alongside other treatments.

Then he said something striking:

• Low scores can mean either a true problem or that you’re simply “out of shape.”
• But: “There’s no case where someone with dementia has a good Brain Gauge score.”

That doesn’t mean a low score equals dementia (it doesn’t). But it suggests that good scores are reassuring, and low scores are a signal: something needs attention—whether that’s recovery, healing, or training.

He also shared an encouraging observation from users:

Some people with early memory loss start training, their scores improve, and they report that their memory improves too.

Mark was careful with claims—and I respect that. But as a functional medicine physician focused on brain health, I find this deeply hopeful.

The future: Brain Gauge Gym and personalized optimization

Mark described ongoing research focused on specificity—learning which scores change with which interventions, so treatments can be fine-tuned (even something like electrode placement in neurofeedback).

He also talked about building out the “Brain Gauge Gym” with platforms for:

• baseline users
• therapeutic needs
• and even elite performers (including athletes focused on reaction time and performance)

And this is where my functional medicine heart sings:

Because with Brain Gauge, you can actually track what improves your brain:

• exercise
• nutrition
• sleep
• fresh air
• supplements
• targeted therapies

Instead of guessing, we can measure.

One more thing: this doesn’t replace exercise

I had to make sure my patients heard this:

Mark did not give anyone permission to skip exercise. 

He said plainly: “I work out every day and that’s very helpful.”

And he shared something powerful:

As we age—especially in our 50s and 60s—the difference between active and sedentary brains becomes enormous.

The encouraging part?

Active people often maintain strong scores.

That’s what we want: resilience, consistency, and strong functional connectivity as we age.

Final thoughts

I’m genuinely excited about this tool.

We’ve had ways to assess brain function over time—imaging, labs, inflammatory and metabolic markers, questionnaires. But Brain Gauge adds something unique:

• It’s easy
• It’s affordable
• It’s biologically based
• It can change over time with interventions
• It helps us measure function, not just structure

And in a practice centered on brain health, prevention, and recovery, that’s invaluable.

Learn more

Mark shared a few ways to learn more:

• The Brain Gauge YouTube channel
• Their website at Cortical Metrics (corticalmetrics.com)
• And he offers free consults through the site

And as always, I invite you to join the Rethink Aging community at caringforthebody.org where you can find more resources on how to better protect your brain, strengthen your body, and live with purpose.

Thanks again for tuning in—and I’ll catch you in the next.

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