May 6, 2025 • 28 mins
Virtual environments are transforming the landscape of clinical care, and Dr. Walter Greenleaf, Research & Innovations Director at the Stanford Medical Mixed Reality Center, is at the forefront of this revolution. In our engaging conversation, Dr. Greenleaf reveals how immersive technologies can enhance cognitive and emotional well-being, ultimately promoting healthier behaviors in patients. We delve into the powerful roles of gaming and storytelling in patient adherence, as well as the promising applications of virtual reality in treating behavioral and mental health issues like post-traumatic stress and addiction. As we explore the convergence of AI, biosensing, and XR technologies, Dr. Greenleaf shares insights on personalized treatment and the ethical considerations that accompany these advancements. Join us to discover how these emerging tools are reshaping patient care and decision-making.
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Episode Transcript
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(00:00):
(upbeat music)
(00:06):
- Welcome to "Stanford Medcast,"
the podcast from Stanford CME
that brings you the latest insights
from the world's leadingphysicians and scientists.
If you're joining us for the first time,
be sure to subscribe on Apple Podcasts,
Amazon Music, Spotify, orYouTube to stay updated
with our newest episodes.
I am your host, Dr. Ruth Adewuya.
(00:29):
Today I am joined by Dr. Walter Greenleaf.
Dr. Greenleaf is a renowned neuroscientist
and digital health innovatorbased at Stanford University,
where he serves as the researchand innovations director
at the Stanford MedicalMixed Reality Center.
With more than four decades of experience
at the intersection of neuroscience,
(00:50):
medical technology, anddigital therapeutics,
he is widely recognized as a pioneer
in applying virtual reality, biosensing,
and AI to clinical care.
His work focuses on developingtools to support behavioral
and physical health challenges,
including PTSD, stroke, anxiety,
cognitive aging, addiction, and autism.
(01:12):
Over the years,
he has led or advised numerousgroundbreaking ventures,
including roles as foundingchief science officer
at Para Therapeutics and senior leadership
at MindMaze and InWorld Solutions,
which developed virtualworlds for behavioral health.
He currently advises anumber of MedTech companies
and investment firms shaping the future
(01:32):
of immersive healthcare.
He also supports initiatives like
the Virtual Human Interaction Lab
and Wearable Electronics Program,
and has served as technology advisor
to organizations including the NIH, NASA,
and the National Science Foundation.
Dr. Greenleaf, welcome to the show
and thanks so much forchatting with me today.
- I'm excited to be here.
I'm looking forward to our conversation.
(01:54):
- You have been at theforefront of digital health
and neuroscience for over 40 years.
Can you take us backto what first drew you
to virtual reality in medicine?
And how has your missionevolved over time?
- I was a graduate studentat Stanford working over
in the Department of Physiology.
In the neuroscience program,
I was studying how hormonesimpact our cognitive processes
(02:17):
and emotional state, andhow that changes with aging.
I also was very excited abouthow we can apply technology
to improve datacollection, data analytics.
As part of that,
I got to know a wonderfullybrilliant person, Jaron Lanier.
Jaron started the firstcommercial virtual reality company
back in 1987.
I got excited becauseI saw some applications
(02:39):
of VR technology within the medical arena
and worked with Jaron to geta license to his technology.
I had started a companywhen I was in grad school
and had sold it,
in the field ofpsychophysiological analysis
and sleep staging.
I had a passion fordeveloping medical products
as opposed to publishingpapers in a journal.
(02:59):
I got started because of my relationship
with one of the founders ofthe technology in the field
and my interest inmoving it into medicine.
- I love your origin story
and how it is connected to someone
that you had met earlieron in your career.
I think it's rare to hear about someone
who not only witnessed thebirth of a new technology,
but immediately saw its medical potential.
(03:22):
As I looked into your work,
it's very clear that you have this passion
for translating innovationinto real-world clinical tools
and how it's shaped thetrajectory of your work.
You've worked across somany different spheres,
academia, MedTech, clinicalprogram development.
How do you balance those worlds?
What has that intersection taught you
(03:43):
about translating researchinto clinical impact?
- For me, it's been fortunate
that I've been at a placelike Stanford University
in Silicon Valley.
The whole idea of a university is for us
to run across other disciplines,
other individuals who are passionate
about the projects they'redoing, have those discussions,
and then develop integrated systems
(04:04):
that benefit from the hybridvigor of having a community
that shares information and discourse.
It's fortunate that beingat the Stanford University,
that there's encouragementto think horizontally
as opposed to vertically.
- Being rooted in a research environment
really does give you thatfreedom to explore, iterate,
stay close to the science
while still thinking about application.
(04:25):
But, of course, to getbroader clinical buy-in,
perception matters.
And many clinicians still associate VR
with gaming or entertainment.
What's the most compellingway you explain its role
in serious clinical care today?
- We need to start with the basics of,
how do virtual environmentsimpact us both cognitively
(04:47):
and emotionally?
And how can that benefit clinical care?
I'm not surprised that people
who haven't had a virtualreality experience would assume
it's for entertainingor for gaming purposes.
But it is a very powerfultool that we can use.
I'll go into detail about some
of the reasons it's impactful.
One of the challengeswe have in healthcare
is promoting adherence.
(05:08):
Often, people are prescribed a medication
or some process thatthey need to go through.
Maybe cognitive behavioral training
or exercise or nutrition.
Because we don't have the feedback loop
for the progress we're making,we often lose the context.
Out of boredom, out of frustration or lack
of appreciating the results,
or maybe 'cause we don't see the benefit
(05:29):
of the time investment orthe economic investment,
people stop, even if it's something
that could be preserving their life
and limbs or their overall health.
What's powerful aboutvirtual environments is
that we can promote adherence
and help people do what they really need
to do to be healthy.
We can show them the results of sticking
to whatever needs to be done.
We have a technique wherewe can, for example,
(05:51):
create an avatar of your future self
that you could meet ina virtual environment,
have a dialogue with your future self,
that can give you feedback, saying,
"Hey, it's really great thatyou got sleep last night
and you've been eatingwell and exercising well.
Look how buff I'm looking20 years in your future.
And look how happy I amand look at my background,
the house I'm in and the car I'm driving."
The other technique we haveis showing people the context
(06:15):
of why they might beneeding to do something
that might be difficult to do.
In this case, we'releveraging what our friends
in the gaming industry and theentertainment industry use,
which is storytelling.
It's with gaming technologyand gambling technology.
Those fields have learned howto get people to come back,
to make things exciting,to make things educational.
(06:36):
Sometimes people are competitive
and wanna be on the leaderboard,
or sometimes they wantto go through a process
to make friends.
Using those tools and thecontext of a virtual environment,
we can create a therapeutic process.
We can evoke a cognitive stateand use that as a challenge
or way of assessing.
We can create the context functionally
for an emotional reaction to a stimulus.
(06:58):
When you're in a virtual environment,
you really feel like you're there.
A clinician can use the power
of exposure therapy therapeutically
or the power of reinforced learning
to help people do what theyneed to do to be healthy.
- That's such a great way to frame it.
Starting with how VR connects to cognition
and emotion grounds the technologyin the human experience.
(07:20):
You're right that untilsomeone actually tries VR,
it's easy to underestimate how immersive
and persuasive it can be.
I really love thatexample of using avatars
and narrative techniques tohelp patients visualize some
of the outcomes and stay engaged.
It flips the script on patientadherence and education.
(07:42):
One area where that kindof immersive engagement
is proving to beimpactful is in behavioral
and mental health.
Can you describe how VRis currently being used
to support behavioral andmental health treatment,
such as PTSD, anxiety, or chronic pain?
- One example of a use case
for treating post-traumaticstress is exposure therapy.
(08:04):
There's a learned fear reaction
that is evolutionarily important
when something is very traumatic for you
and you want to avoid it.
You've learned to have a anxiety reaction
to what might be a common stimulus.
You might be driving down the highway,
and you look over andyou see a pile of trash
on the side of the road,
and it triggers a fear reaction
(08:25):
'cause of the time youwere in a combat zone.
Wherever the trauma came from,
you've learned to have a evokedfear response to a stimulus.
We can habituate that response.
We can teach you the cognitive skills
to manage that response,
if we can give you acontrolled exposure to it.
A clinician would be askingyou to imagine that trauma
(08:47):
and try and give you theskills to respond to it,
but your brain doesn't want to go there.
With a virtual environment,
we can gradually exposeyou to that stimulus.
If you fear flying,
we can have you look overat the dining room table
and see tickets for travel there.
The next step might be
to have you be drivingin a taxi to the airport.
The next step might be waitingin line to board the plane.
(09:09):
During those exposures,
we're teaching you how tothink about the process
and to manage youremotional reaction to it,
and giving you the skills to do that.
Same thing for helping withcravings and addictions.
We can put you in a virtual bar scene
and have you practicewhat you're going to say
to your friends who areputting peer pressure on you
to have another drink.
We can make small steps
and give you the skills to manage that.
(09:31):
You're also asked about managing pain.
We've had some wonderfulvalidated interventions
using RCT trials to demonstrate
that by using virtual environment
as a way to both distractyou from the pain
and then also learningthe cognitive skills
to manage chronic pain,
people can learn to handle thatlearned fear reaction, too.
(09:52):
For generalized anxiety disorders,
we can give you the tools to see yourself
from a third-person perspective,
practice how to handle thething that you're anxious about,
give you the skills ofhow to handle something.
We can slow things down, orwe can change the context,
and you can learn how tomanage that fear reaction.
VR is very useful for diagnostics, too.
(10:14):
I love the example ofstroke rehabilitation
or traumatic brain injury rehabilitation
because it does show that here's a process
that an individual does need to go through
to recover from physical trauma.
We can show you the progress dynamically.
You're doing it at home.
The clinician can get a status report
as to whether we need tochange it or discharge you.
(10:35):
It's a fantastic example of howbeing able to both motivate,
measure, give feedback, andadjust the protocol precisely
for the individual.
- Those are really compelling use cases
and explanations forhow VR can be utilized.
When you talk about gradual exposure
in a safe, controlled environment
and pairing that with skill building,
(10:55):
it really highlights thetherapeutic potential of VR.
It also makes me think of what's happening
beneath the surface,
what's going on in the brainduring these interventions.
You've written extensively on this.
Could you just walk us through
how immersive environmentsinfluence brain function
in a therapeutic context?
- What's great aboutclinical VR systems is
(11:16):
that they create contextof learning and retention.
Because we're creating an experience,
we also can motivate peopleby giving some sort of goal
that you're shooting for,some sort of feedback,
depending on what motivatesthe individual users.
What might motivate oneperson would be competition.
What might motivate anotherperson might be exploration
(11:38):
and learning.
By making the experience pleasant,
we're facilitating learningand retention and changing
in our neuro-system.
We shorten the reward feedback loop,
and we show progress to the individual.
We can also provideinsight and perspective
by changing time and point of view.
We create a context, wereinforce the reason to do it,
(12:00):
we show why it's important, andwe make it fun and engaging.
- The idea that VR doesn'tjust teach information,
but creates memorable,emotionally resonant experiences
that actually shift howthe brain learns and adapts
and being able tocompress the feedback loop
or shift perspectives reallyopens up possibilities
(12:20):
for deeper insight andsustained change in this space.
We know that insight
and experience are justpart of the picture.
We're also thinking aboutoutcomes and evidence.
With that in mind,
what does the currentclinical research say
about the effectivenessof VR-based therapy?
- We've been doing research
on VR therapies for severaldecades, but it's taken a while
(12:41):
because the technology has been evolving,
and what might be thestate-of-the-art technology
three years ago is no longerthe state of technology.
And also, previously, thecost made it difficult
to do large-scale research.
However, now we've had theopportunity to do several large
and well-controlled trialsto show the efficacies
of this approach to bothimproved assessments
(13:02):
and improved interventions.
We've been able to show thatby using virtual environments
to facilitate neurorehabilitation,
we can make the progress faster.
We can also demonstratethrough validated trials
that in the long run, weget much better results,
more precise results,
faster results in therehabilitation process.
(13:23):
The trials that we'vedone are now significant
to show the power and theimpact of this technology
on different clinical zones,
but it's been done withrelatively small sample sizes.
And we have more to demonstrate.
We're now, again, at a new era,
with a new strata of technologythat I think will be able
to be demonstrated as beingmore precise and more robust.
(13:45):
But we'll need to expend ourresearch to validate that.
- I can appreciate the challenge of trying
to think about outcomes,
especially when you talk about
how dynamic this space is and the idea
that the state-of-the-artconcept evolves so quickly.
But it is encouraging hereboth the pace of research
and the real-world cliniciangains and their convergence.
As more clinicians becomeinterested in using these tools,
(14:06):
I imagine practical implementation becomes
the next big hurdle.
So let's talk about that.
What are the key considerationswhen implementing VR
into clinical practice?
And what advice do youhave for early adopters?
- There's a lot of amazing academic groups
and early-stage companiesthat are pioneering new ways
of assessments and newtherapeutics in this zone.
(14:28):
The challenge is understandinghow to bring this
into the clinical environment.
Clinics are very busy.
Clinics can be cost constrained.
And new technology won't be adopted
unless it's designed to fit seamlessly
into the work environment.
Considerations such as, wheredo we store the headsets?
Who's gonna charge them?
If we send it home with the patient,
how does it send informationback to the clinician?
(14:50):
Many of those issues are being addressed,
but we still have a lot of work to do.
We've now shown very adequatelythe value therapeutically
of these technologies to addresscertain clinical problems.
What needs to be demonstratednow is their impact
on reducing costs and makingthings a little bit smoother
and easier in the clinic.
Which will happen, but wehave some work to do there.
(15:12):
- That's such a grounded perspective.
It's so easy to getexcited about innovation,
but the reality is
that even the most promisingtech won't succeed unless,
as you mentioned, it's built to fit
into the day-to-day realitiesof clinical practice.
This idea of designing for ease
and integration is just as important
as designing for impact.
(15:33):
I heard you say that at Stanford,
you are uniquely positioned to shape
how these technologiesare tested and refined.
As research and innovations director
at the Stanford MedicalMixed Reality Center,
what are some key projectsthat you're working on
that clinicians should keep an eye on?
- One thing.
I'm excited by Dr. Kim Bullock's work over
in the Department of Psychiatry.
(15:54):
She's using VR clinicallyto address a number
of different behavioral health problems.
I'm excited by what's being done over
at the Stanford Children's Hospital,
where virtual environmentsare being used to help
with stress inoculation,
helping somebody beprepared for the experience
of coming into the hospitaland having a procedure done,
and also to distract fromuncomfortable procedures,
(16:16):
infusions, or even needle punctures.
In terms of basic research,
I'm excited by what's going on
at the Stanford VirtualHuman Interaction Lab,
where Jeremy Bailenson'sgroup is understanding how VR
and AR technology changes ourbehavior and our attitudes,
and what can be done to use that both
for education and for training.
(16:37):
There's a spectrum of workbeing done at Stanford,
and it's exciting to see that.
There's also a lot of work being done
at other academic centers onthe cusp of where, clinically,
the technology's movingbeyond the early adopters
and into the broader healthcare ecosystem.
In particular, with the use of VR systems
for stroke rehabilitation,
(16:57):
I think we're seeing some great strides
and acceptance there.
The other thing I think we should keep
our eye on is new ways
of doing assessments usingvirtual reality simulations.
We can create a context thatevokes an emotional response,
or a context that challengesour cognitive processes.
A head-bound display isactually a wearable device
that collects a lot of information.
(17:19):
You can understand eyegaze, facial expressions,
voice tone and movement/body language,
the behavioral response,
and the emotion response to a stimulant.
This gives us ways toobjectively measure things
that previously before wewere measuring subjectively,
asking the patient,
"How did that medicationimpact you last week?"
or, "How are you feeling now?"
(17:40):
Hard to do quantitatively.
Now we have someenvironments that we can use
in an age-appropriate andculturally relevant manner
to measure how someonereacts to a stimulus.
It's hard for clinical care todo more precise measurements
of diagnostic processesand how a patient is doing
as they progress in their therapy.
- It's quite encouraging tohear how this work is scaling,
(18:02):
not just at Stanford, butacross academic centers,
into broader healthcare systems.
And the example that you gave of how VR
is being used not onlyfor stroke rehabilitation,
but also re-imagininghow we assess condition
and emotional responseis truly remarkable.
Creating immersive,emotionally relevant contexts
(18:22):
while simultaneously capturingpsychophysiological data
sounds like a level of insightthat maybe we've never had
before in real time.
It feels like we're really moving
towards a truly adaptive model of care.
Which brings me to my next question.
AI, biosensing, and XRare converging rapidly.
(18:43):
Can you share examples of
how the synergy is enablingpersonalized treatment
or clinical decision making?
- We can evaluatesomeone's progress through,
let's use the exampleof post-traumatic stress
that we talked about earlier.
We can not only evaluatesomeone's response to a stimulus
by creating a stimulus in a context,
(19:04):
we can also measure heartrate variability, respiration,
eye gaze to see what they'relooking at or avoiding.
If we create a context forthem to do some exploration
or interact with other people,
we can see, through bodylanguage, voice tone, eye gaze,
facial expression, so muchabout how they're doing
and what is grabbing their attention,
(19:25):
and quantify that and usea more precision approach
for that individual.
And we can also use those sametechnologies for training.
If we're going through trying
to learn the three-dimensionalrepresentation
of the spinal tracts, for example,
we can do that in a way.
Because we can measurethe individual's attention
and cognitive load of the process,
(19:47):
we can speed things up or slow them down
based on their learnings.
I'm excited about the ability
to measure the psychomotor movement.
Teaching a surgical skill, for example,
we can see how somebodyis doing that process
and give them the feedback.
How to learn to do that process
at their pace, on their own timescale,
and compare how they're doing compared to
(20:09):
how they were doing the day before.
And not just precision therapeutics,
but precision education and training.
- That notion really excites me as someone
who is in the medical education field.
The fact that the sametechnology can be flipped
for clinician training,
whether it's learning a new procedure,
just reinforces how versatile
and scalable the technology is.
(20:29):
With all of this reachdata comes a new layer
of responsibility,especially around privacy,
consent, and ethical use.
What are some of the mostpressing ethical challenges
we need to be thinking about?
- I'm so glad you brought this up
'cause it is something thatwe need to get on top of
as soon as possible.
Because we're able understandan individual's response
to a stimulus, because wecan measure how they learn
(20:53):
or how they respond to information,
and because we're collectingvery precious data
about someone's emotionalstate and cognitive state
in a quantifiable manner, weneed to protect that data.
There's a wonderful book
that I recommend called"The Battle for Your Brain."
It goes into detail aboutsome of the concerns
that are out there involvingthe data we're collecting
about individual cognitive processes,
(21:14):
and how that data could be used
in a nonclinical contextto sell us things,
or to influence ourattitudes and behavior.
If we have the misfortuneof living in a dictatorship,
that same approach andsame technology can be used
to identify dissidents.
It's the type of information that we need
to make sure we understandthe importance of it
and find new ways of protecting it
(21:36):
so that it can't be usedin an adverse manner.
- What I heard from you isan important caution that,
while the technologyholds so much promise,
we can't overlook the risks.
What you talked about,
how data could be usedoutside of clinical care,
or even weaponized in the wrong hands,
makes it a little bit sobering
and underscores the needto build ethical guardrails
(21:58):
into the systems from the very beginning.
Along those lines,
not only does it raisequestions about privacy,
but also about access.
Equity is always a concernwith digital health tools.
How can we ensure that VRimproves healthcare access
instead of exacerbating disparities,
especially in remote or underserved areas?
(22:18):
- One of the things I'mexcited about is the potential
for virtual environmentsystems to reduce disparities
and be used as a telemedicine platform
to reach underserved areas.
There's a real thrust right now
of conducting distributed clinical trials.
In other words, not having people come
into an academic medical center,
but being able tocollect the data in situ,
wherever they're livingand whatever they're doing.
(22:40):
Sending a low-costheadset home with a person
to help motivate them, toshow them their progress,
and also to connect people with others
and also connect peoplewith their clinician
for post-discharge follow-up.
One of the things that we should be ready
for is a big surge inimprovement in the technology
when it comes to havingit be more multi-user.
(23:02):
We're now getting to the point where
with pixel streaming andcloud-based rendering,
that we can have very robust,
very photorealistic environments
where other people can be there, too.
We can create an AI system of a clinician
who can answer questions for the patient
for post-discharge follow-up,
or before they come in for a session,
collect the information that's needed.
(23:24):
We can support group therapy.
And we can also create group experiences
for rehabilitation.
We now have generative AI
to help us customize the environments.
We can make sure thatthey're age appropriate,
or represent the culture of the individual
who's having the experience.
We can use this technologyboth to reach out
to underserved populations
(23:45):
and use it as a home health hub
to both motivate andmeasure and get feedback.
I'm also hopeful
that it can be a waywe can conduct research
in underserved populations.
One example of where thingsare moving along really well
is at the US VeteransHealth Administration.
They have scaled to everyveterans health hospital
and clinic the use of VR,and they were using it
(24:06):
for more than 30 differentclinical indications.
And the VA healthcaresystem is, in many ways,
a safety net healthcare network.
A lot of people who arestruggling with issues
such as homelessness ormental health issues are part
of that system.
With their ability to reach out and cover,
in a nationwide manner,
data collection and analyticsand provide therapies,
(24:26):
I think we'll be able to reach broader
than we otherwise wouldwith other technologies.
- The fact that we can now deliver
highly realistic immersive environments
to underserved communitieswithout the need
for expensive infrastructurecould really reframe
what equitable carelooks like in the future.
And it sounds like it has the potential
to transform not just access,
(24:48):
but also outcomes and patient autonomy.
So building on that vision
and looking 5 to 10 years ahead,
what XR or VR applications do you believe
will be most transformativein clinical practice?
- I'm very worried about the fact
that we have an aging populationand smaller family sizes.
And it'll be hard to providethe informal care support.
(25:11):
As we get up into our80s and 90s and beyond,
we're gonna be living so much longer
than previous generations,
but we haven't yet really comeup with the impactful ways
of supporting the health challenges
that happen with aging and neuro-dementia.
There's so many issues thatwe need to make progress on.
(25:32):
And I'm excited
about the way virtualenvironments are being used
to refine research into the neuroscience
and challenges of cognitive aging.
I'm hoping that we can use this technology
to help empower a new wave of research,
come up with new therapeutics
to address some of these problems.
That's my optimistic hope,
that these very powerfultechnologies can be used
(25:53):
to facilitate researchand improve clinical care.
- That's a deeply important point related
to our aging population.
And it's encouraging to hear
that VR is already helpingus better understand
and potentially intervenein some of those conditions.
But I think it ultimately really speaks
to the role immersive technologycan play in both prevention
and preservation of quality of life.
(26:14):
For clinicians who are listening,
maybe curious, maybe skeptical,
what's one actionable insight
or step that they cantake to begin engaging
with this emerging field?
- The first step is if youhaven't had the experience
of using today's virtualreality technology,
find a way to do that,
even if it's borrowinga friend's VR headset
(26:34):
and playing a game,
or finding a place that itis being used clinically.
Another way is take a lookat the research literature.
We now have thousands of papersvalidating the impact of VR
for different clinical conditions.
There are summary articles
and review articlesshowing the impact of VR
in different clinical zones.
Another pathway is to check out,
(26:55):
there's several organizations
that are assembling people doing research
and clinical care in this arena
of the International VirtualReality Health Association.
We also have a journal ofvirtual reality medicine
that is worth taking a look at.
Cedar-Sinai puts on ayearly meeting called vMed,
where clinicians andtechnologists convene together
(27:15):
to look at what's usefuland talk about the results.
There's many ways to get familiar with it.
And many of the early-stage companies
that are developing thesetechnologies are eager
to provide access.
If someone is curious,I wouldn't be surprised
if it would not be hardto get a loaner system
to try out and see how it can be used
in your particular clinic or arena.
(27:37):
- I appreciate howapproachable that advice is.
Essentially, try it, borrow aheadset, explore the research,
and take a look at the incredible work
that's already happening in this space.
My other takeaway fromthis conversation is
that you don't have to bea technologist to begin
to understand how VR canenhance your clinical practice.
(27:58):
I think all it takes is being curious
and being willing to engage.
Dr. Greenleaf, this has been
such an insightful conversation.
Thank you so much for sharingyour expertise with us.
- Thank you. It's been my pleasure.
- This episode was broughtto you by "Stanford CME."
To claim CME forlistening to this episode,
click on the Claim CME link below,
or visit medcast.stanford.edu.
(28:21):
Check back for new episodes by subscribing
to "Stanford Medcast" whereveryou listen to podcasts.
(bright music)
(upbeat music)
(00:06):
- Welcome to "Stanford Medcast,"
the podcast from Stanford CME
that brings you the latest insights
from the world's leadingphysicians and scientists.
If you're joining us for the first time,
be sure to subscribe on Apple Podcasts,
Amazon Music, Spotify, orYouTube to stay updated
with our newest episodes.
I am your host, Dr. Ruth Adewuya.
(00:29):
Today I am joined by Dr. Walter Greenleaf.
Dr. Greenleaf is a renowned neuroscientist
and digital health innovatorbased at Stanford University,
where he serves as the researchand innovations director
at the Stanford MedicalMixed Reality Center.
With more than four decades of experience
at the intersection of neuroscience,
(00:50):
medical technology, anddigital therapeutics,
he is widely recognized as a pioneer
in applying virtual reality, biosensing,
and AI to clinical care.
His work focuses on developingtools to support behavioral
and physical health challenges,
including PTSD, stroke, anxiety,
cognitive aging, addiction, and autism.
(01:12):
Over the years,
he has led or advised numerousgroundbreaking ventures,
including roles as foundingchief science officer
at Para Therapeutics and senior leadership
at MindMaze and InWorld Solutions,
which developed virtualworlds for behavioral health.
He currently advises anumber of MedTech companies
and investment firms shaping the future
(01:32):
of immersive healthcare.
He also supports initiatives like
the Virtual Human Interaction Lab
and Wearable Electronics Program,
and has served as technology advisor
to organizations including the NIH, NASA,
and the National Science Foundation.
Dr. Greenleaf, welcome to the show
and thanks so much forchatting with me today.
- I'm excited to be here.
I'm looking forward to our conversation.
(01:54):
- You have been at theforefront of digital health
and neuroscience for over 40 years.
Can you take us backto what first drew you
to virtual reality in medicine?
And how has your missionevolved over time?
- I was a graduate studentat Stanford working over
in the Department of Physiology.
In the neuroscience program,
I was studying how hormonesimpact our cognitive processes
(02:17):
and emotional state, andhow that changes with aging.
I also was very excited abouthow we can apply technology
to improve datacollection, data analytics.
As part of that,
I got to know a wonderfullybrilliant person, Jaron Lanier.
Jaron started the firstcommercial virtual reality company
back in 1987.
I got excited becauseI saw some applications
(02:39):
of VR technology within the medical arena
and worked with Jaron to geta license to his technology.
I had started a companywhen I was in grad school
and had sold it,
in the field ofpsychophysiological analysis
and sleep staging.
I had a passion fordeveloping medical products
as opposed to publishingpapers in a journal.
(02:59):
I got started because of my relationship
with one of the founders ofthe technology in the field
and my interest inmoving it into medicine.
- I love your origin story
and how it is connected to someone
that you had met earlieron in your career.
I think it's rare to hear about someone
who not only witnessed thebirth of a new technology,
but immediately saw its medical potential.
(03:22):
As I looked into your work,
it's very clear that you have this passion
for translating innovationinto real-world clinical tools
and how it's shaped thetrajectory of your work.
You've worked across somany different spheres,
academia, MedTech, clinicalprogram development.
How do you balance those worlds?
What has that intersection taught you
(03:43):
about translating researchinto clinical impact?
- For me, it's been fortunate
that I've been at a placelike Stanford University
in Silicon Valley.
The whole idea of a university is for us
to run across other disciplines,
other individuals who are passionate
about the projects they'redoing, have those discussions,
and then develop integrated systems
(04:04):
that benefit from the hybridvigor of having a community
that shares information and discourse.
It's fortunate that beingat the Stanford University,
that there's encouragementto think horizontally
as opposed to vertically.
- Being rooted in a research environment
really does give you thatfreedom to explore, iterate,
stay close to the science
while still thinking about application.
(04:25):
But, of course, to getbroader clinical buy-in,
perception matters.
And many clinicians still associate VR
with gaming or entertainment.
What's the most compellingway you explain its role
in serious clinical care today?
- We need to start with the basics of,
how do virtual environmentsimpact us both cognitively
(04:47):
and emotionally?
And how can that benefit clinical care?
I'm not surprised that people
who haven't had a virtualreality experience would assume
it's for entertainingor for gaming purposes.
But it is a very powerfultool that we can use.
I'll go into detail about some
of the reasons it's impactful.
One of the challengeswe have in healthcare
is promoting adherence.
(05:08):
Often, people are prescribed a medication
or some process thatthey need to go through.
Maybe cognitive behavioral training
or exercise or nutrition.
Because we don't have the feedback loop
for the progress we're making,we often lose the context.
Out of boredom, out of frustration or lack
of appreciating the results,
or maybe 'cause we don't see the benefit
(05:29):
of the time investment orthe economic investment,
people stop, even if it's something
that could be preserving their life
and limbs or their overall health.
What's powerful aboutvirtual environments is
that we can promote adherence
and help people do what they really need
to do to be healthy.
We can show them the results of sticking
to whatever needs to be done.
We have a technique wherewe can, for example,
(05:51):
create an avatar of your future self
that you could meet ina virtual environment,
have a dialogue with your future self,
that can give you feedback, saying,
"Hey, it's really great thatyou got sleep last night
and you've been eatingwell and exercising well.
Look how buff I'm looking20 years in your future.
And look how happy I amand look at my background,
the house I'm in and the car I'm driving."
The other technique we haveis showing people the context
(06:15):
of why they might beneeding to do something
that might be difficult to do.
In this case, we'releveraging what our friends
in the gaming industry and theentertainment industry use,
which is storytelling.
It's with gaming technologyand gambling technology.
Those fields have learned howto get people to come back,
to make things exciting,to make things educational.
(06:36):
Sometimes people are competitive
and wanna be on the leaderboard,
or sometimes they wantto go through a process
to make friends.
Using those tools and thecontext of a virtual environment,
we can create a therapeutic process.
We can evoke a cognitive stateand use that as a challenge
or way of assessing.
We can create the context functionally
for an emotional reaction to a stimulus.
(06:58):
When you're in a virtual environment,
you really feel like you're there.
A clinician can use the power
of exposure therapy therapeutically
or the power of reinforced learning
to help people do what theyneed to do to be healthy.
- That's such a great way to frame it.
Starting with how VR connects to cognition
and emotion grounds the technologyin the human experience.
(07:20):
You're right that untilsomeone actually tries VR,
it's easy to underestimate how immersive
and persuasive it can be.
I really love thatexample of using avatars
and narrative techniques tohelp patients visualize some
of the outcomes and stay engaged.
It flips the script on patientadherence and education.
(07:42):
One area where that kindof immersive engagement
is proving to beimpactful is in behavioral
and mental health.
Can you describe how VRis currently being used
to support behavioral andmental health treatment,
such as PTSD, anxiety, or chronic pain?
- One example of a use case
for treating post-traumaticstress is exposure therapy.
(08:04):
There's a learned fear reaction
that is evolutionarily important
when something is very traumatic for you
and you want to avoid it.
You've learned to have a anxiety reaction
to what might be a common stimulus.
You might be driving down the highway,
and you look over andyou see a pile of trash
on the side of the road,
and it triggers a fear reaction
(08:25):
'cause of the time youwere in a combat zone.
Wherever the trauma came from,
you've learned to have a evokedfear response to a stimulus.
We can habituate that response.
We can teach you the cognitive skills
to manage that response,
if we can give you acontrolled exposure to it.
A clinician would be askingyou to imagine that trauma
(08:47):
and try and give you theskills to respond to it,
but your brain doesn't want to go there.
With a virtual environment,
we can gradually exposeyou to that stimulus.
If you fear flying,
we can have you look overat the dining room table
and see tickets for travel there.
The next step might be
to have you be drivingin a taxi to the airport.
The next step might be waitingin line to board the plane.
(09:09):
During those exposures,
we're teaching you how tothink about the process
and to manage youremotional reaction to it,
and giving you the skills to do that.
Same thing for helping withcravings and addictions.
We can put you in a virtual bar scene
and have you practicewhat you're going to say
to your friends who areputting peer pressure on you
to have another drink.
We can make small steps
and give you the skills to manage that.
(09:31):
You're also asked about managing pain.
We've had some wonderfulvalidated interventions
using RCT trials to demonstrate
that by using virtual environment
as a way to both distractyou from the pain
and then also learningthe cognitive skills
to manage chronic pain,
people can learn to handle thatlearned fear reaction, too.
(09:52):
For generalized anxiety disorders,
we can give you the tools to see yourself
from a third-person perspective,
practice how to handle thething that you're anxious about,
give you the skills ofhow to handle something.
We can slow things down, orwe can change the context,
and you can learn how tomanage that fear reaction.
VR is very useful for diagnostics, too.
(10:14):
I love the example ofstroke rehabilitation
or traumatic brain injury rehabilitation
because it does show that here's a process
that an individual does need to go through
to recover from physical trauma.
We can show you the progress dynamically.
You're doing it at home.
The clinician can get a status report
as to whether we need tochange it or discharge you.
(10:35):
It's a fantastic example of howbeing able to both motivate,
measure, give feedback, andadjust the protocol precisely
for the individual.
- Those are really compelling use cases
and explanations forhow VR can be utilized.
When you talk about gradual exposure
in a safe, controlled environment
and pairing that with skill building,
(10:55):
it really highlights thetherapeutic potential of VR.
It also makes me think of what's happening
beneath the surface,
what's going on in the brainduring these interventions.
You've written extensively on this.
Could you just walk us through
how immersive environmentsinfluence brain function
in a therapeutic context?
- What's great aboutclinical VR systems is
(11:16):
that they create contextof learning and retention.
Because we're creating an experience,
we also can motivate peopleby giving some sort of goal
that you're shooting for,some sort of feedback,
depending on what motivatesthe individual users.
What might motivate oneperson would be competition.
What might motivate anotherperson might be exploration
(11:38):
and learning.
By making the experience pleasant,
we're facilitating learningand retention and changing
in our neuro-system.
We shorten the reward feedback loop,
and we show progress to the individual.
We can also provideinsight and perspective
by changing time and point of view.
We create a context, wereinforce the reason to do it,
(12:00):
we show why it's important, andwe make it fun and engaging.
- The idea that VR doesn'tjust teach information,
but creates memorable,emotionally resonant experiences
that actually shift howthe brain learns and adapts
and being able tocompress the feedback loop
or shift perspectives reallyopens up possibilities
(12:20):
for deeper insight andsustained change in this space.
We know that insight
and experience are justpart of the picture.
We're also thinking aboutoutcomes and evidence.
With that in mind,
what does the currentclinical research say
about the effectivenessof VR-based therapy?
- We've been doing research
on VR therapies for severaldecades, but it's taken a while
(12:41):
because the technology has been evolving,
and what might be thestate-of-the-art technology
three years ago is no longerthe state of technology.
And also, previously, thecost made it difficult
to do large-scale research.
However, now we've had theopportunity to do several large
and well-controlled trialsto show the efficacies
of this approach to bothimproved assessments
(13:02):
and improved interventions.
We've been able to show thatby using virtual environments
to facilitate neurorehabilitation,
we can make the progress faster.
We can also demonstratethrough validated trials
that in the long run, weget much better results,
more precise results,
faster results in therehabilitation process.
(13:23):
The trials that we'vedone are now significant
to show the power and theimpact of this technology
on different clinical zones,
but it's been done withrelatively small sample sizes.
And we have more to demonstrate.
We're now, again, at a new era,
with a new strata of technologythat I think will be able
to be demonstrated as beingmore precise and more robust.
(13:45):
But we'll need to expend ourresearch to validate that.
- I can appreciate the challenge of trying
to think about outcomes,
especially when you talk about
how dynamic this space is and the idea
that the state-of-the-artconcept evolves so quickly.
But it is encouraging hereboth the pace of research
and the real-world cliniciangains and their convergence.
As more clinicians becomeinterested in using these tools,
(14:06):
I imagine practical implementation becomes
the next big hurdle.
So let's talk about that.
What are the key considerationswhen implementing VR
into clinical practice?
And what advice do youhave for early adopters?
- There's a lot of amazing academic groups
and early-stage companiesthat are pioneering new ways
of assessments and newtherapeutics in this zone.
(14:28):
The challenge is understandinghow to bring this
into the clinical environment.
Clinics are very busy.
Clinics can be cost constrained.
And new technology won't be adopted
unless it's designed to fit seamlessly
into the work environment.
Considerations such as, wheredo we store the headsets?
Who's gonna charge them?
If we send it home with the patient,
how does it send informationback to the clinician?
(14:50):
Many of those issues are being addressed,
but we still have a lot of work to do.
We've now shown very adequatelythe value therapeutically
of these technologies to addresscertain clinical problems.
What needs to be demonstratednow is their impact
on reducing costs and makingthings a little bit smoother
and easier in the clinic.
Which will happen, but wehave some work to do there.
(15:12):
- That's such a grounded perspective.
It's so easy to getexcited about innovation,
but the reality is
that even the most promisingtech won't succeed unless,
as you mentioned, it's built to fit
into the day-to-day realitiesof clinical practice.
This idea of designing for ease
and integration is just as important
as designing for impact.
(15:33):
I heard you say that at Stanford,
you are uniquely positioned to shape
how these technologiesare tested and refined.
As research and innovations director
at the Stanford MedicalMixed Reality Center,
what are some key projectsthat you're working on
that clinicians should keep an eye on?
- One thing.
I'm excited by Dr. Kim Bullock's work over
in the Department of Psychiatry.
(15:54):
She's using VR clinicallyto address a number
of different behavioral health problems.
I'm excited by what's being done over
at the Stanford Children's Hospital,
where virtual environmentsare being used to help
with stress inoculation,
helping somebody beprepared for the experience
of coming into the hospitaland having a procedure done,
and also to distract fromuncomfortable procedures,
(16:16):
infusions, or even needle punctures.
In terms of basic research,
I'm excited by what's going on
at the Stanford VirtualHuman Interaction Lab,
where Jeremy Bailenson'sgroup is understanding how VR
and AR technology changes ourbehavior and our attitudes,
and what can be done to use that both
for education and for training.
(16:37):
There's a spectrum of workbeing done at Stanford,
and it's exciting to see that.
There's also a lot of work being done
at other academic centers onthe cusp of where, clinically,
the technology's movingbeyond the early adopters
and into the broader healthcare ecosystem.
In particular, with the use of VR systems
for stroke rehabilitation,
(16:57):
I think we're seeing some great strides
and acceptance there.
The other thing I think we should keep
our eye on is new ways
of doing assessments usingvirtual reality simulations.
We can create a context thatevokes an emotional response,
or a context that challengesour cognitive processes.
A head-bound display isactually a wearable device
that collects a lot of information.
(17:19):
You can understand eyegaze, facial expressions,
voice tone and movement/body language,
the behavioral response,
and the emotion response to a stimulant.
This gives us ways toobjectively measure things
that previously before wewere measuring subjectively,
asking the patient,
"How did that medicationimpact you last week?"
or, "How are you feeling now?"
(17:40):
Hard to do quantitatively.
Now we have someenvironments that we can use
in an age-appropriate andculturally relevant manner
to measure how someonereacts to a stimulus.
It's hard for clinical care todo more precise measurements
of diagnostic processesand how a patient is doing
as they progress in their therapy.
- It's quite encouraging tohear how this work is scaling,
(18:02):
not just at Stanford, butacross academic centers,
into broader healthcare systems.
And the example that you gave of how VR
is being used not onlyfor stroke rehabilitation,
but also re-imagininghow we assess condition
and emotional responseis truly remarkable.
Creating immersive,emotionally relevant contexts
(18:22):
while simultaneously capturingpsychophysiological data
sounds like a level of insightthat maybe we've never had
before in real time.
It feels like we're really moving
towards a truly adaptive model of care.
Which brings me to my next question.
AI, biosensing, and XRare converging rapidly.
(18:43):
Can you share examples of
how the synergy is enablingpersonalized treatment
or clinical decision making?
- We can evaluatesomeone's progress through,
let's use the exampleof post-traumatic stress
that we talked about earlier.
We can not only evaluatesomeone's response to a stimulus
by creating a stimulus in a context,
(19:04):
we can also measure heartrate variability, respiration,
eye gaze to see what they'relooking at or avoiding.
If we create a context forthem to do some exploration
or interact with other people,
we can see, through bodylanguage, voice tone, eye gaze,
facial expression, so muchabout how they're doing
and what is grabbing their attention,
(19:25):
and quantify that and usea more precision approach
for that individual.
And we can also use those sametechnologies for training.
If we're going through trying
to learn the three-dimensionalrepresentation
of the spinal tracts, for example,
we can do that in a way.
Because we can measurethe individual's attention
and cognitive load of the process,
(19:47):
we can speed things up or slow them down
based on their learnings.
I'm excited about the ability
to measure the psychomotor movement.
Teaching a surgical skill, for example,
we can see how somebodyis doing that process
and give them the feedback.
How to learn to do that process
at their pace, on their own timescale,
and compare how they're doing compared to
(20:09):
how they were doing the day before.
And not just precision therapeutics,
but precision education and training.
- That notion really excites me as someone
who is in the medical education field.
The fact that the sametechnology can be flipped
for clinician training,
whether it's learning a new procedure,
just reinforces how versatile
and scalable the technology is.
(20:29):
With all of this reachdata comes a new layer
of responsibility,especially around privacy,
consent, and ethical use.
What are some of the mostpressing ethical challenges
we need to be thinking about?
- I'm so glad you brought this up
'cause it is something thatwe need to get on top of
as soon as possible.
Because we're able understandan individual's response
to a stimulus, because wecan measure how they learn
(20:53):
or how they respond to information,
and because we're collectingvery precious data
about someone's emotionalstate and cognitive state
in a quantifiable manner, weneed to protect that data.
There's a wonderful book
that I recommend called"The Battle for Your Brain."
It goes into detail aboutsome of the concerns
that are out there involvingthe data we're collecting
about individual cognitive processes,
(21:14):
and how that data could be used
in a nonclinical contextto sell us things,
or to influence ourattitudes and behavior.
If we have the misfortuneof living in a dictatorship,
that same approach andsame technology can be used
to identify dissidents.
It's the type of information that we need
to make sure we understandthe importance of it
and find new ways of protecting it
(21:36):
so that it can't be usedin an adverse manner.
- What I heard from you isan important caution that,
while the technologyholds so much promise,
we can't overlook the risks.
What you talked about,
how data could be usedoutside of clinical care,
or even weaponized in the wrong hands,
makes it a little bit sobering
and underscores the needto build ethical guardrails
(21:58):
into the systems from the very beginning.
Along those lines,
not only does it raisequestions about privacy,
but also about access.
Equity is always a concernwith digital health tools.
How can we ensure that VRimproves healthcare access
instead of exacerbating disparities,
especially in remote or underserved areas?
(22:18):
- One of the things I'mexcited about is the potential
for virtual environmentsystems to reduce disparities
and be used as a telemedicine platform
to reach underserved areas.
There's a real thrust right now
of conducting distributed clinical trials.
In other words, not having people come
into an academic medical center,
but being able tocollect the data in situ,
wherever they're livingand whatever they're doing.
(22:40):
Sending a low-costheadset home with a person
to help motivate them, toshow them their progress,
and also to connect people with others
and also connect peoplewith their clinician
for post-discharge follow-up.
One of the things that we should be ready
for is a big surge inimprovement in the technology
when it comes to havingit be more multi-user.
(23:02):
We're now getting to the point where
with pixel streaming andcloud-based rendering,
that we can have very robust,
very photorealistic environments
where other people can be there, too.
We can create an AI system of a clinician
who can answer questions for the patient
for post-discharge follow-up,
or before they come in for a session,
collect the information that's needed.
(23:24):
We can support group therapy.
And we can also create group experiences
for rehabilitation.
We now have generative AI
to help us customize the environments.
We can make sure thatthey're age appropriate,
or represent the culture of the individual
who's having the experience.
We can use this technologyboth to reach out
to underserved populations
(23:45):
and use it as a home health hub
to both motivate andmeasure and get feedback.
I'm also hopeful
that it can be a waywe can conduct research
in underserved populations.
One example of where thingsare moving along really well
is at the US VeteransHealth Administration.
They have scaled to everyveterans health hospital
and clinic the use of VR,and they were using it
(24:06):
for more than 30 differentclinical indications.
And the VA healthcaresystem is, in many ways,
a safety net healthcare network.
A lot of people who arestruggling with issues
such as homelessness ormental health issues are part
of that system.
With their ability to reach out and cover,
in a nationwide manner,
data collection and analyticsand provide therapies,
(24:26):
I think we'll be able to reach broader
than we otherwise wouldwith other technologies.
- The fact that we can now deliver
highly realistic immersive environments
to underserved communitieswithout the need
for expensive infrastructurecould really reframe
what equitable carelooks like in the future.
And it sounds like it has the potential
to transform not just access,
(24:48):
but also outcomes and patient autonomy.
So building on that vision
and looking 5 to 10 years ahead,
what XR or VR applications do you believe
will be most transformativein clinical practice?
- I'm very worried about the fact
that we have an aging populationand smaller family sizes.
And it'll be hard to providethe informal care support.
(25:11):
As we get up into our80s and 90s and beyond,
we're gonna be living so much longer
than previous generations,
but we haven't yet really comeup with the impactful ways
of supporting the health challenges
that happen with aging and neuro-dementia.
There's so many issues thatwe need to make progress on.
(25:32):
And I'm excited
about the way virtualenvironments are being used
to refine research into the neuroscience
and challenges of cognitive aging.
I'm hoping that we can use this technology
to help empower a new wave of research,
come up with new therapeutics
to address some of these problems.
That's my optimistic hope,
that these very powerfultechnologies can be used
(25:53):
to facilitate researchand improve clinical care.
- That's a deeply important point related
to our aging population.
And it's encouraging to hear
that VR is already helpingus better understand
and potentially intervenein some of those conditions.
But I think it ultimately really speaks
to the role immersive technologycan play in both prevention
and preservation of quality of life.
(26:14):
For clinicians who are listening,
maybe curious, maybe skeptical,
what's one actionable insight
or step that they cantake to begin engaging
with this emerging field?
- The first step is if youhaven't had the experience
of using today's virtualreality technology,
find a way to do that,
even if it's borrowinga friend's VR headset
(26:34):
and playing a game,
or finding a place that itis being used clinically.
Another way is take a lookat the research literature.
We now have thousands of papersvalidating the impact of VR
for different clinical conditions.
There are summary articles
and review articlesshowing the impact of VR
in different clinical zones.
Another pathway is to check out,
(26:55):
there's several organizations
that are assembling people doing research
and clinical care in this arena
of the International VirtualReality Health Association.
We also have a journal ofvirtual reality medicine
that is worth taking a look at.
Cedar-Sinai puts on ayearly meeting called vMed,
where clinicians andtechnologists convene together
(27:15):
to look at what's usefuland talk about the results.
There's many ways to get familiar with it.
And many of the early-stage companies
that are developing thesetechnologies are eager
to provide access.
If someone is curious,I wouldn't be surprised
if it would not be hardto get a loaner system
to try out and see how it can be used
in your particular clinic or arena.
(27:37):
- I appreciate howapproachable that advice is.
Essentially, try it, borrow aheadset, explore the research,
and take a look at the incredible work
that's already happening in this space.
My other takeaway fromthis conversation is
that you don't have to bea technologist to begin
to understand how VR canenhance your clinical practice.
(27:58):
I think all it takes is being curious
and being willing to engage.
Dr. Greenleaf, this has been
such an insightful conversation.
Thank you so much for sharingyour expertise with us.
- Thank you. It's been my pleasure.
- This episode was broughtto you by "Stanford CME."
To claim CME forlistening to this episode,
click on the Claim CME link below,
or visit medcast.stanford.edu.
(28:21):
Check back for new episodes by subscribing
to "Stanford Medcast" whereveryou listen to podcasts.
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