Dr. Kim Bullock 

Hello, and welcome back to Psychiatry XR. Today, I'm joined by my co-host Faaizah Arshad.

Faaizah Arshad 

Hi, Kim.

Dr. Kim Bullock

Hi, Faaizah. Today, we're so excited to have Dr. Cassondra Eng join our conversation. Dr. Cassondra Eng is an NIH-funded 32 postdoctoral scholar at Stanford University's Department of Psychiatry and Behavioral Sciences, my home as well. She earned her PhD from the Psychology Department at Carnegie Mellon University with a specialization in developmental neuroscience and educational technology. Her research focuses on developing active VR intervention to foster executive function with neurodiverse populations with a focus on the neural mechanisms underlying behavioral changes using advanced mobile, noninvasive neuroimaging, functional nerves, and her interdisciplinary research bridges cognitive neuroscience, learning sciences, developmental psychology, and human computer interaction to optimize immersive contexts that foster brain and cognitive functioning crucial to overall well-being and success. Welcome, Cassie.

Dr. Cassie Eng 

Thank you, Kim. I'm so excited to be here.

Dr. Kim Bullock

Well, it's so great to have you, and since we have a lot of non-scientists listeners and interdisciplinary stakeholders in this space, I was wondering if you could just introduce your recent work that you're doing at kind of a high level, the forest rather than the trees, to people who've never really thought about VR in the context of neurodiversity. Do you kind of maybe talk about what you do and what your recent work is finding?

Dr. Cassie Eng

Yes. So first, thank you for the wonderful introduction. And so, as Kim said, what I focus on is executive function, which are these cognitive processes that subserve goal directed behavior, planning, organizing,[and] resisting distractions. And we know executive function is really important because it not only predicts later academic achievement, but also physical health outcomes like obesity, the likelihood of committing crimes, and also job and interpersonal success. But executive function is really this umbrella term, but what I really focus on is attention, which falls under executive function processes. So attention and also brain development associated with attention. And so what I've been designing is these active virtual reality interventions to improve attention. And this has been, you know, important and really been a focus in the past few years, because there has been increasing concerns of decline in sustained attention, especially after the pandemic hit.

Dr. Kim Bullock

 Oh, wow. Okay, could you tell us a little bit about your project in detail or any findings that you've found so far?

Dr. Cassie Eng

Yeah, so I'm really excited to share the research that I've been doing here at Stanford. So, the neuroimaging that I use, functional near-infrared spectroscopy, also known as F nears, uses low levels of light to image the brain. So, how does it differ from other neuroimaging techniques? So, the most common ones used in the field are fMRI, but that requires people to stay still, completely still, and they're in a loud scanner. It's also really expensive, so like, around $500 a scan. And then there's EEG, which, you know, looks at the direct firing of neurons, but it is really sensitive to motion artifacts. My background is actually in an EEG lab. You have to remove every single idling, every single muscle movement, from those scans. So it's really sensitive to motion and then there's more invasive procedures, like PET scans, where you actually inject that radioactive tracer. So, you can imagine that these types of techniques aren't the most child-friendly, but also for psychiatric or neurodiverse populations who don't like sitting still for long periods of time. F near has really changed that because it is less sensitive to motion artifacts. So, we can use this neuroimaging technique while people are in motion. And what I mean by that is in naturalistic settings, and, you know, doing these whole body movements that people are doing in their everyday behavior. So if you're asking, how does virtual reality come into play here? There's always this hard balance of doing this if we control the experiments in labs because the question is always, you know, how does this generalize? How does this generalize to real-world behavior? Then, when you do experiments in the real world, it's like, how do you control for all these environmental factors that might be changing the results? [With] VR, you can simulate real-world context, but you can control the environment. And so you can look at things like attention and brain development while people are actively moving and executing naturalistic body movements, but in virtual reality. So it's kind of going towards this movement of using real-time brain imaging but controlling for that environment.  

Dr. Kim Bullock

 Got it. And how did you control for that environment? What kind of simulated experiences have you delivered?

Dr. Cassie Eng

Yeah, you both have probably heard of these before, but brain games, cognitive training apps, commercialized digital health products, are really targeting improvements in executive function, improvements in attention. But there are a lot of concerns about whether these actually work. Do they transfer? Do they actually improve executive function in the real world? What we do from the literature is that exercise, exercise improves executive function. High aerobic exercise, cognitively demanding exercise. But the challenge here is that some people don't like exercising, and sedentary behavior has been increasing in the United States. And these date back to, you know, foundational studies with actual rodent vitals like way back to the 50s. But even to this day, they show that these environments that with both cognitive and exercise stimulation, also known as enriched environments, increased neuroplasticity prefrontal cortex development, which we know underlies executive function development, but it's been really hard to replicate these studies with humans because if you think about how, you put rats in a cage, you have this exercise environment with those rodent wheels, a very cognitively stimulating environment, so like really colorful tubes and enriching things to play with. And then a combined environment, an enriched environment with both an exercise, those running wheels, and then the cognitively enriching things, and those together show the most increases in alteration in brain structure and function from these enriched environments. But you can imagine a really, carefully controlling these things. Designing an experiment for humans might be very difficult. So that is what I have been able to do in virtual reality. So I have these really carefully controlled conditions that modify the amount of exercise and cognitive demands. And I do find that these enriched environments, so the ones that increase both physical activity and cognitive stimulation, increase executive function compared to just sedentary cognitive training, exercise training alone, just a control condition. But importantly, it's not just changes in executive function, but also changes in functional connectivity. And these changes in functional connectivity, specifically in the prefrontal cortex, are associated with those changes in executive function. So really showing you know research-based virtual reality interventions, they can actually have these beneficial effects on cognition and brain development.

Dr. Kim Bullock

Got it and did you have to create your own content in the VR to create that controlled condition, or did you use something that was already commercially available?

Dr. Cassie Eng

Yes, some of them. My earlier work with children actually is, I did develop the games from the ground up, custom designed. Because a lot of commercialized video games, also known as exercise-based video games, it's really hard to modify those. And what I found with children. So these were in immersive environments not in virtual reality, meaning I had games projected onto a wall. So they were immersed in the environment and they responded with a dance pad. So, I hacked into a Dance Dance Revolution and that is how they responded. And yes, what it did show is that the condition with the most exercise and cognitive demands changes in prefrontal cortex development, increases in executive function. Importantly, teachers rated their executive function-related behavior in the classroom as better. So, there's that transfer here at Stanford. What I wanted to do was take something that is existing, one of the most popular commercial exercise-based VR games, and so I took Beat Saber, it's a rhythm based game for slice arrows to the beat of songs, and then I made modifications that commercially existing game because again, back to this question of, are people really using this in the real world? And if they are, does it have beneficial effects? I think one of the biggest concerns with video game use technology in general is, you know, is this bad? Is this bad for brain development? Is this bad for attention? Yeah, and so I'm kind of on the flip side here, saying that, you know, when you combine it with things that we know that are good for brain cognitive development, like exercise, could it actually be beneficial.

Dr. Kim Bullock 

Got it.

Faaizah Arshad

So you mentioned that you've worked with children, and I was also looking at some of your prior research with how you particularly worked with low-income children and also neurodiverse populations. So, I just wonder if you can speak more about the different populations that you know you've worked with and maybe, like, who the audience is for your current research and even if you've seen, like, varying findings across populations,

Dr. Cassie Eng

Yeah, that is a great question. And so, you know, one of the main reasons I came here to Stanford is my earlier work with children. What I found is that the children who benefited the most from these enriched immersive environments were the children who had the lowest executive function starting out. And so we know that early intervention is crucial for executive function development and has these cascading effects and all these later important outcomes. But we also know is that executive function impairments are commonly found in individuals with Attention Deficit Hyperactivity Disorder, also known as ADHD, and so when I came to the Psychiatry Department at Stanford, there's accessibility to individuals with ADHD, and this is a different age group, adolescents, young adults, not only diagnosed with ADHD, but who might be experiencing attentional difficulties in general. This is both personally important to me, but you know, understudied in the area, but ADHD is commonly undiagnosed or misdiagnosed, specifically in women. Kim probably knows more about this too, but a lot of the diagnostic criteria for ADHD was done on studies with boys. More impulsivity, hyperactivity. There's also societal pressures for girls growing up to be more organized and well-behaved, so they might change their behavior, such as, you know, volunteering to be the classroom helper, or, you know, finding ways to move around and navigate, and it's not until adulthood where they're experiencing more executive function demand, right? Less parental supervision, more self management. And so that is why I'm recruiting both those with an ADHD diagnosis, but also those who might just be experiencing attentional difficulties, in case they might need this type of intervention the most.

Faaizah Arshad

Got it. That makes sense. Thank you.

Dr. Kim Bullock

I know your goal is to create interventions and going back, I'm so curious about your use of commercial VR, what's existing, and then you said you adapted it, and did you, for other scientists out there trying to innovate interventions, I mean, there's one advantage to having something that's already disseminated, that's been taken to market and everything, and then seeing if you can incorporate it into an intervention versus taking that and modifying it. So, did you work with the company to modify it, or did you take the existing game and then add things to it? Or just that process of using something commercial and integrating it into your basic science and developing an intervention?

Dr. Cassie Eng

Yeah, it definitely does. And something that was very, very challenging that I experienced when building a game from the ground up for children, was incredibly challenging, because, you know, it goes from all the components that go into creating a game, a narrative, the music, the sound effects. Is it developmentally appropriate? You know, it took a lot of collaboration with childhood educators, yeah, game developers, and a lot of pilot testing, you know.

Dr. Kim Bullock

Yeah, and why not just use something off the shelf that a company's already developed and put all their resources in.

Dr. Cassie Eng

Yeah. So, I think one of the reasons why I had to go this route is because a lot of the existing research on exercise based video games, they would compare, you know, playing Wii Fit to conditions such as sedentary playing, something like Super Mario World. Those environments and those game mechanics are completely different. So by building something I had this very carefully controlled narrative and the overarching goals of the game, but to create my cognitive training condition, children were still playing it, but they were sitting. They were exposed to the exact same stimuli, but less exercise, activity, same immersive environment, but I reduced the amount of inhibitory control needed to progress in the game, so it was more repetitive motor movements. So, same exercise but less cognitive demands. And then a control group, which, in developmental research, we know is important to control for maturation and practice effects. And I don't want to say this isn't for trying, because, you know, the team of even like game developers I was working with creating a game in virtual reality is very different from creating a queue game. It's way more complex. So something like a commercial game, it depends on the console system, but if, say, Beat Saber on a PlayStation, for example, which they do offer, you can't make modifications to it. But you can, if you hook it up to Steam, which is a game platform. A lot of game developers use it. Beat Saber is available in there, but what you can do is make modifications to the game through this software, and that's how I was able to do it.

Dr. Kim Bullock

Oh, got it, yeah, like building from the ground up, versus, you know, using something commercial and then, like, the barriers and then the opportunities that in XR in a space, and then working with neurodiverse and attention and executive functioning and in a pediatric population. And just, yeah, we've never had anything like this.

Dr. Cassie Eng

And you, you know this, Kim, you work with patients, but working with human subjects, actually doing the research with them is completely different. There's these nuances to human behavior that you have to take into account. Even, I think the first time that I was piloting just the VR, having the CDC recommend around, you know, an hour of exercise for young adults late adolescence. And I remember when I first piloted, and these were healthy young adults, the headset was too heavy, just on their cheekbones, and so I had to, I would use Meta’s Elite Strap, which is ergonomical and it helps with balance. But when I paired that with mirrors, neuroimaging modality I used, there's constraints to the Opto placement. So, then I had to find this, like, happy medium, where it reduced the weight off of people's cheek bones, but it didn't interfere with the neuroimaging.

Dr. Kim Bullock 

Yeah.

Dr. Cassie Eng

You're really taking into account people's comfort so it doesn't interfere with their own experience with VR.

Dr. Kim Bullock 

Yeah, yeah.

 Faaizah Arshad

I'm also curious, since you've mentioned attention multiple times, if you thought of looking at eye tracking in VR and attention that way. I was looking back at some of the studies you've done, and I know you've done, like, used eye tracking technology in the past, but I wonder if you see yourself using that more immersively as a tool to look at attention as well.

 Dr. Cassie Eng

Yeah, that is also a really good question, because yes, you are right, a lot of my prior work use eye tracking for their attention, but the outcomes were a little different looking at reading comprehension, academic achievement, and it was really on multimedia design, ebooks where children are allocating their attention while they're reading, but in these virtual spaces. Do I think that eye tracking metrics would be interesting and important to understand some of the cognitive processes happening? Yes, but right now, I will say there are limitations to the design. So yes, we have portable neuroimaging and we have wireless VR headsets, so it's a lot of gear on someone's head, and took a lot of pilot testing to make sure participants are comfortable and it isn't interfering with their ability to actually participate in the game itself. But there’s near infrared light, pulse oximeters, which you've probably seen at the doctor's offices, one source, one detector that emits light, and so that is the same technology, but there's many sources and detectors around the head. A lot of eye tracking technology also emits the same light.

Dr. Kim Bullock

It might interfere.

Dr. Cassie Eng

Yes, so.

Faaizah Arshad

Ah, interesting.

Dr. Cassie Eng

I remember walking to the lab and I saw these, you know, really high tech eye tracking glasses. They look like normal glasses, and I was like, Oh, can I possibly use that? But I know that prior researchers in the lab said that they found out very quickly that light interferes with the neuro signals. Okay, in the future, if there's some way to block out that interference, then, like, yes, let's collect that eye tracking data. But I know even especially for these exercise-based active VR interventions, you know, I do recommend participants to come in if they do wear glasses, to wear contacts. Okay, great. So you have the VR headset and also the neuroimaging. So I think that eye tracking would be interesting, but there are some challenges right now.

Faaizah Arshad

Makes sense.

Dr. Kim Bullock

I’m so curious. I have so many questions for you. What are the primary outcome measures that you're currently focused on in your studies?

Dr. Cassie Eng

Yeah, so there's a few outcome measures. So I have task-based measures of executive function that have been used in the psychology literature for a few decades. So selective attention tasks, sustained attention tasks, measures of cognitive flexibility and inhibitory control. And I also have self reports.

Dr. Kim Bullock

Okay. And do you do those in VR or do you do those separately?

Dr. Cassie Eng

I do those separately the way they're administered. It's pretty standardized down to the size of the stimuli on the screen for certain tasks and some also physical activity enjoyment. Because I think one of the most challenging aspects of exercise interventions is that some people don't want to exercise.

Dr. Kim Bullock

Got it.

Dr. Cassie Eng

And not just exercise enjoyment, but not only like, would they continue participating in this game, but also, would they recommend it to a friend in the HCI research is a good indicator, yes, of like, continued use. So what I'm seeing in the really active conditions I have is people's heart rates are getting in that high intensity zone. So really, getting that aerobic workout, we know, is good for cardiovascular health, but what I'm interested in is they also find it an enjoyable activity. You know, is this not only an intervention that can improve executive function, brain development, but also cardiovascular health, without people even realizing or exercising that hard.

Dr. Kim Bullock

Thank you for that. And what are the biggest barriers that you've encountered with incorporating XR, VR in your research that maybe you would appreciate people creating XR that would help you in your research? 

Dr. Cassie Eng

I think that one of the biggest challenges is that F nears is still in its infancy stages. So, when fMRI was first released, I mean, there's so many pipelines too right now, fMRI has a pretty standard pre-processing pipeline and post-processing pipeline, but I think it's been really challenging figuring out methods to make sure that the near signals, you know, they have high signal to noise ratio with that much movement, making sure that we're still getting clean signal. So it took around a year of pilot testing and making changes to the hardware and also developing a statistical pipeline to remove all those motion artifacts. So a lot of collaboration with F nears experts, engineers.

Dr. Kim Bullock

So, would XR that's compatible with F nears be where we need to innovate the most?

Dr. Cassie Eng

So, I think that right now, I'm going to publish this soon, but a full detailed protocol of how you can integrate VR and F nears without sacrificing participant comfort. But I think there's gonna really change the landscape of the types of opportunities this is going to offer if we can really look at neural activity, neural connectivity while people are really immersed in different virtual environments. There's so many different studies or questions to answer. But, as I said, the right now concern is, is technology. Is this good for attention, for brain development? And so, I think actually really conducting these carefully controlled studies before releasing it into the wild and saying that it does. 

Dr. Kim Bullock

Yes, absolutely.

Faaizah Arshad

I'm also curious to hear about what your advice would be to students who are sort of entering the research space in VR or who are interested in leading their own studies, because I think you've been super successful at that, and whether it's writing or doing the experimentation and the research, what advice would you share?

Dr. Cassie Eng

So, my advice to share, because I am a Carnegie Mellon University alum, and I'm from Pittsburgh, and I'm for well-developed technology. Mr. Rogers Neighborhood was one of the first, you know, educational TV shows that was released, and one of his famous quotes is, there will always be helpers. Ask for help, and that's okay. And I don't think this is just specific to academia and science, but it can be very isolating if you try to do projects alone. And Kim knows this because I've reached out to her just from a practicing clinician's perspective on things, but a lot of the work that this takes, you know, really reaching out to other experts in the field, so game developers, policy makers, clinicians, neuroscientists, and just asking, what's your input on this? And I've always found that people are always more than willing to help, but you have to ask for it.

Dr. Kim Bullock

Thank you. That is such great advice. And yeah, it's a team sport that it's innovating and the scientific method, and you're so thorough with it. Do you have any long term career plans like 10 years from now? Do you have anything in the XR space that you're hoping or wanting or looking forward to or anything else you think is relevant for the audience?

Dr. Cassie Eng

Right now? I think I'm in the proof of concept stage. So as I said, it took, it was effortful to create an entire PhD, to create a game from the ground up. Yes, I was like, you know, before I do this again, let's do something commercial, make modifications, see if this generalizes to another age group. Yes, how plastic is the brain? And so far from the preliminary results, these enriched environments that you know increase both exercise activity and also cognitive demands, that split second decision making attention does improve executive function and also functional connectivity in the prefrontal cortex, and those changes are associated with those changes in executive function. So I'm still in the data collection phase right now, because I gotta have a power example to make any claims about the research. But these active VR experiences really are beneficial, especially for neurodiverse people with ADHD, for people who are struggling with attention regulation that I think, really collaborating with others, XR/VR developers in making these types of games into an intervention tool. And in terms of F nears, you know, can we use the changes that we're seeing during the actual VR experience? Can we use those to predict their outcomes, how much they actually benefit from it?

Faaizah Arshad

Like long term as well.

Dr. Cassie Eng

That's right. Yeah, right. And this is it's a little separate from the VR space, and mostly with using nears. But I do think that the neuroimaging modality it's going to be paired with virtual reality is the future, because it allows that freedom of movement in spaces. But something that I wish I knew coming in is, you know, I used nears during my PhD, but I really only focused on the prefrontal cortex, so just like the front of the frontal lobe, and when I came here to Stanford, it was, oh, like you can do, like a full head coverage, more data, frontal parietal network, which we know is associated with attention development. When I put on a full head montage. For the first time, I was like, why is this signal so noisy? My hair? There is a reason that the most nearest publications, if you look early on, the most, are with infants and elderly populations. And I don't think that's a coincidence. Less hair. Yeah. So I actually consulted with barbers and hair stylists, cosmetologists in San Francisco, specifically black barbers and hairstylists, and also researchers doing this work on the proper tools. What is appropriate to use for different types of hair texture is because, as I said, you know, large part of my work is being more inclusive, so women with ADHD, women with intentional difficulties, but also having a representative sample race and ethnicity. And in the region, I do have a diverse sample with very different types of hair colors and textures. So the lab, I feel like people would be so confused because it looks like a virtual reality lab and neuroscience lab and also a hair salon. I think advice in general for those who want to use mirrors is that you do have to account for hair.

Dr. Kim Bullock

Okay? And maybe developers in XR who want to integrate with nears need to know that too.

Dr. Cassie Eng

Yeah.

 Faaizah Arshad

Do you think you've been able to account for that well enough? Are you still working on it, like on making it kind of more perfect?

Dr. Cassie Eng

Yeah, so I collaborate closely with Dr. Jasmine Kwasa. She's actually doing a Fulbright in Kenya right now, but she actually is really getting into 3D printing mirrors and EEG caps from more diverse hair textures and colors. So there's a cross collaboration with her.

And I actually just gave a talk at cognitive development society, specifically about how methods for taking into account different types of hair colors and textures for nears data collection and with children and also adolescents.

But there are just a large amount of tools to comb hair, which kind of removes the static. And the standard in both F nears and EEG research is kind of using, it's like hypoallergenic gel and the back of Q tips to kind of move around hair. And that doesn't work for everyone. So I actually use combs with larger teeth and braid gel. And I learned this from a stylist in San Francisco, and that actually keeps hair in place.

Dr. Kim Bullock

 Wow, yeah, a lot of these details need to be innovated for the technology. It's got a long way to go, it sounds like, to make it user friendly.

Dr. Cassie Eng

Yeah, and I think that this is really difficult getting scientific findings out there to, like, spread all this knowledge, because, you know, some article publications, you have to condense to around, like, 10 pages. But if people actually saw the protocol that I had to develop for this study, it's like 100 pages. Like, here's a step-by-step of how to do it, but let me just condense it.

Dr. Kim Bullock

Yeah, well, that's good. This podcast can be a way to, to get that information out, because that is important information that you had to do so much. Maybe that'll motivate developers. Do you think it will?

 Dr. Cassie Eng

I'm very much for the Open Science movement that's happening. So once an article is published, everything, including my pre-processing pipeline, my gigantic protocol, is all made publicly available on Open Science Framework. This is to make sure that anyone who wants to do this type of work doesn't have to go through all of the challenges that bring this project to fruition so they can just use it.

Dr. Kim Bullock 

Well, yeah. I feel like there's a lot in the future, and we'll have to have you come again. So much more I'd love to talk with you about but we'll leave it here, and thank you so much for joining us. Dr. Eng, I know you have a lot that you're doing, and you're so prolific. I don't know how you do it all.

Faaizah Arshad 

Thank you so much. It's been really great.

Dr. Kim Bullock 

Yeah, it's been such a pleasure; really fascinating.

Dr. Cassie Eng

Thank you so much, both Faaizah and Kim, for having me here. It is an honor, and I really appreciate the amount of diverse perspectives you've been bringing to this podcast.

 Dr. Kim Bullock 

Thank you for that.

 Faaizah Arshad

Thank you.

Dr. Kim Bullock 

That's it for this episode of Psychiatry XR. We hope you gained a new perspective on using extended reality in healthcare, and thank you so much for listening. This episode was brought to you by Psychiatry XR, the psychiatry podcast about immersive technology and mental health. And for more information about Psychiatry XR, visit our website at psychiatryxr.com, and be sure to subscribe to the podcast and tune in again next month to hear from another guest about XR use in psychiatric care.  

You can join us monthly on Apple podcast, Twitter, Spotify or wherever you get your podcast. Psychiatry XR was produced by myself, Kim Bullock, Faaizah Arshad, and Jessica Hagen.

And please note the podcast is distinct from my own clinical teaching and research roles at Stanford, and the information provided is not medical advice and should not be considered or taken as replacement for medical advice. The episode was edited by David Bell and music and audio produced by Austin Hagen. See you next time.