Stimulating the brain with sound

In which Stanford radiologists Kim Butts Pauly and Raag Airan explain how to treat brain disorders with sound
Nicholas Weiler
From Our Neurons to Yours Wu Tsai Neuro Podcast

As we gain a better understanding of how misfiring brain circuits lead to mental health conditions, we'd like to be able to go in and nudge those circuits back into balance. But this is hard — literally — because the brain is encased in this thick bony skull. Plus, often the problem you want to target is buried deep in the middle of a maze of delicate brain tissue you need to preserve.

Today we're going to be talking with neuroscientists who aim to solve this problem with sound. And not just any sound: ultrasound.

Kim Butts Pauly and Raag Airan from the Stanford Department of Radiology are developing ultrasound technology in a couple of different ways to essentially reach into the brain to treat brain disorders that are otherwise hard to access. These uses of ultrasound haven't yet reached the clinic, but could be entering clinical testing in people in the next few years. 
 

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This episode was produced by Michael Osborne at 14th Street Studios, with production assistance by Morgan Honaker. Our logo is by Aimee Garza. The show is hosted by Nicholas Weiler at Stanford's Wu Tsai Neurosciences Institute and supported in part by the Knight Initiative for Brain Resilience. 

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Episode Transcript

Nicholas Weiler:

Welcome back to From Our Neurons to Yours from the Wu Tsai Neurosciences Institute at Stanford University, bringing you as always to the frontiers of neuroscience. 

Today, stimulating the brain with sound. 

But before we get to the conversation, we're going to bring you our new news segment, which we're calling updates from Wu Tsai Neuro. We haven't quite figured out the name for this yet. I wanted to call it "Beyond the Blood-Brain Barrier", but Michael wouldn't allow it. So if you have a suggestion for a cleverer title, please let us know. 

Today I want to tell you about some news we just announced at the institute. We've got a new group of postdoctoral researchers. Postdocs are something that we don't talk about that much, but it's such an important time in the career of a researcher and also at the frontiers of the field. If you listen closely to our show, you'll hear a lot of researchers who are now at the top of their field talking about things they did when they were a postdoc in someone's lab. A postdoc basically is that liminal space between finishing your doctoral dissertation and starting your own lab. It's the first time these researchers are really directing their own scientific exploration, and that work often turns into major breakthroughs in our understanding or tomorrow's transformative technology for neuroscience. So indulge me for a second. I'm going to do this rapid-fire. We've got 10 new postdocs, five of them supported by the Wu Tsai Neurosciences Institute, five of them supported by the Knight Initiative for Brain Resilience here at the Institute. Don't worry if you don't get this all. That's kind of the point because there's a lot. 

Here's the list. We've got postdoctoral scientists working on engineering viruses to target brain cancer using acetylcholine, the neurotransmitter to boost cognitive flexibility, understanding how cellular garbage disposal keeps our brains healthy and could lead to dementia when it goes wrong. Finding ways to protect the optic nerve in glaucoma patients, building computer models of how our brains shift between goals, understanding how Alzheimer's disease spreads undetected in the brain, researching the biology of heat-sensing neurons in worms, studying the molecular traffic control in our cells that is implicated in neurodegeneration and the synaptic molecules that allow us to learn and looking at ways to boost the brain's immune cells to fight dementia. 

So there's a lot of really exciting science going on here. We'll include our announcement with all of these awesome scientists in our show notes. 

But for now, let's talk about brain stimulation.

As our understanding of the brain increases as we learn how an imbalance in a particular mood circuit is linked to the despair felt by someone with clinical depression, or how cross-wiring in the reward system makes it so hard for someone with a substance addiction to stay in recovery. As we gain a better understanding of the brain circuits that determine our mental health, we'd like to be able to go in and nudge those circuits back into balance. But this is obviously hard, literally hard because the brain is encased in this thick bony skull, and often the problem you want to target is buried deep in the middle of this maze of brain tissue, which ideally you'd prefer not to damage.

A while back, we had Nolan Williams on the show and he talked to us about transcranial magnetic stimulation, TMS, where basically you're applying a magnetic field through the skull to change how brain circuits are functioning. That technology is now approved by the FDA to treat certain forms of depression, and the potential for TMS is very exciting, but it's not the only technology out there that might allow us to get deep into the brain in a non-invasive way. We don't have to cut through the skull. A different approach the one we're going to be talking about on the show today is in development in laboratories here at Stanford and elsewhere. Instead of magnets, it uses ultrasound. Now, when you hear ultrasound, you probably think of an image of a baby in the womb on someone's refrigerator.

Ultrasound is a well-established technology for medical imaging, but today's guests are doing more than just taking pictures. 

Kim Butts Pauly and Raag Airan from the Stanford Department of Radiology are developing ultrasound technology in a couple of different ways to essentially reach into the brain to treat brain disorders that are otherwise hard to access. These uses of ultrasound haven't yet reached the clinic, but could be entering clinical testing in people in the next few years. 

Kim Butts Pauly, Raag Airan, welcome to From Our Neurons to Yours.

Kim Butts Pauly:

Thanks so much. So happy to be here.

Raag Airan:

So happy to be here. Thanks so much.

Nicholas Weiler:

So I wonder if, Kim, if you could start us off very briefly, what is ultrasound and why is it an exciting tool for neuroscience right now? If it's useful, maybe you can contrast this for our listeners with TMS pros and cons, how they're complementary. If not, we can come back to that later.

Kim Butts Pauly:

Yeah, sure. So what we're talking about is ultrasound, meaning that it's sound waves, so pressure waves that can go through materials such as water or brain tissue, and that it's at a frequency that's higher than we normally hear. So that's what ultrasound means. The promise here, or the beauty of this technology is that we can use sort of a large area transducer, maybe something like the size of a hockey puck, and then we can focus down to a point deep in the brain.

Nicholas Weiler:

So the transducer is the thing that's generating the ultrasound?

Kim Butts Pauly:

That's right. Yeah. So a transducer is a material like a piezoelectric material that will vibrate and it'll send vibrations into the material that's right beside it. So you put it up against the head, it's going to send vibrations or sound waves through the skull and into the brain. The beauty of this technology is that something as big as, say, a hockey puck that you put up against the skull, then we can focus down to a point deep in the brain. Often I think of it about the size of a jellybean. Then there's so many interesting questions about what is sound doing. We know that we have mechanical sensitive ion channels in the brain, and so what we're thinking is that what's happening is the ultrasound goes in and focuses to a point that then we're creating different types of strains in the tissue, that the neurons are getting stretched and compressed ever so gently, just a very slight compression or strains on the neurons, and that's causing these mechanical sensitive ion channels to fire.

Nicholas Weiler:

Great. And I want to come back to that in more detail. What do you see as the sort of big picture of the application here in neuroscience? Why do we need this technology?

Kim Butts Pauly:

So there's so many things that are applications for treatments that are deep in the brain. TMS, for example, really is very good at getting across the skull, but it doesn't have the focus that ultrasound has and can't go deep in the brain with small focal spots. And in addition, ultrasound has the possibility for being very much more flexible that we can potentially both increase neuronal activity and with different sets of parameters decrease neuronal activity. We can use it in combination with drug delivery, with either brain barrier opening or with nanoparticle delivery that Raag is going to talk about. So very flexible technology.

Nicholas Weiler:

Fantastic. And Raag, yeah, I'd love for you to talk about that. So you are developing this technology in a very particular way, not to stimulate neurons at all, in fact, but almost as a non-invasive surgical tool. I'm tempted to call it a sonic screwdriver. Can you tell us about the clinical need here and what makes ultrasound a great tool for this kind of thing?

Raag Airan:

Yeah, so I'll first say that, I mean, I was introduced to this field as a graduate student and medical student here at Stanford when I heard Kim talking about it. And what I was really thinking about then was the current dominant form of noninvasive neuromodulation that is used every day, which is pharmacology. That is the dominant way that we treat neurologic and psychiatric disorders is pills or infusions, and it works.

Nicholas Weiler:

Right. We give drugs and it changes behavior. It changes the brain.

Raag Airan:

Exactly. And we note that it changes the brain in mostly positive ways. And so, yeah, not to be too cynical about it, just recognizing that that is a great starting point. Now, the downsides are that these drugs don't necessarily do everything that we want, and many cases yield side effects, whether due to action on the rest of the body outside the nervous system that we sometimes forget as neuroscientists. Also, the brain and spinal cord, and peripheral nervous system is a really heterogeneous system.

An action of the same drug at one part of the nervous system can have very different and even counteracting effects to the therapeutic effect that we might want due to its action at a given target. What I learned from Kim is that ultrasound is really great at making these tight focal spots of energy delivery at pretty much anywhere we might want in the nervous system. And so the question was, well, could we use that power of ultrasound to deliver the energy to bias the delivery of these drugs, to given parts of the nervous system so that we can try to have our cake and eat it too by maximizing the on-target therapeutic effects that we want and minimizing the off-target side effects.

Nicholas Weiler:

So in other words, making it possible for the drugs to only active in a particular spot that they're going to be most effective, and the drug is just ignored everywhere else.

Raag Airan:

Yeah, ideally, or at the least macro dose at the site and microdose everywhere else, really get as much as we can on-target versus off-target effects.

Nicholas Weiler:

Okay. I mean, the thing that seems so amazing about this technology is, as you've both mentioned, that it gives you the ability to put this dose of energy somewhere deep in the brain, and it sounds like deeper than you could go with transcranial magnetic stimulation. And also it's a physical stimulus in a sense, not a magnetic stimulus. If I understand correctly, TMS is going to interact with the magnetic fields of brain circuits and maybe switch circuits on and off, but if you want to do something that's not electrical, if you want to do something that's physical, this technology would also be really valuable.

So I want to delve a little bit more into this question of what exactly is going on when you are testing this tool, using it for brain stimulation in Kim's case, or something like releasing a drug in Raag's case. Let's start with Kim. I understand there was a different form of ultrasound approved by the FDA back in 2016 for treating essential tremor by zapping tiny groups of cells in the thalamus to get rid of that tremor. But what you're developing is much gentler than that, and potentially, I think wider in application. What can you tell us about how focused ultrasound actually works to stimulate brain cells?

Kim Butts Pauly:

Yeah, sure. So just to be very clear, the work that you were talking about before was very high intensity where it would go on for a long duration, continuously in order to heat up the tissue and cause a thermal lesion. So that's not at all what we're trying to do here. We're going to use much lower intensities by several orders of magnitude, and then we might intersperse it, sort of pulse it on with time delays in between. So we stretch it out in time but with much, much less power.

Nicholas Weiler:

You're just tickling the cells a little bit.

Kim Butts Pauly:

Yeah, a little bit. And so the general idea is that we do have mechanical sensitive ion channels, and so we can create some strains in the tissue. And one of the things I'm very interested in is what is the effect that we're creating that I need to be able to say to my clinician colleagues, this is the effect that I want. You need to dial up and down.

Nicholas Weiler:

Got it. And just to make sure I understood what you're saying, is that what we're discovering is that the brain cells, the neurons are actually sensitive to physical stimulation to the kinds of vibrations and stretching that you can trigger with ultrasound. You mentioned there being ion channels, and so these are these little pores that all of our nerve cells have. Those are basically what give nerve cells their electrical sensitivities. Do I have that right?

Kim Butts Pauly:

Yeah. I would say that we're not completely a hundred percent sure about this, but one of the possibilities is that we are opening up some channels and we're more or less just depolarizing the neurons a little bit. So the opportunity for them to spontaneously fire increases or maybe that they don't repolarize at the same rate. That's one of the possibilities is that we're not having a huge effect. We don't think what we have is like with TMS, where with TMS you can have evoke a motor response in the hand. We don't see that at all. What we see is a much more subtle effect.

Nicholas Weiler:

So you're making the neurons maybe a little bit more likely to fire, you're not forcing them to fire potentially. And again, as you said, this is the working hypothesis. It's pretty subtle in that way.

Kim Butts Pauly:

Yeah. And if that effect is actually strain on those mechanical sensitive ion channels, then let me dig a little deeper and to understand what those strains are. So I actually had a graduate student who was looking at this, and so what we found was that there's normal strains on neurons that are due from particle motion suggests that as you think about sound waves, it's a pressure wave that goes through the brain and that the particles or particles or neurons will move forwards and backwards very gently. And as they move forwards and backwards, there's a time when they're stretched a little bit and a time when they're compressed a little bit as that pressure wave is moving through the brain. And that sort of stretch and compression is what's called a normal strain.

We can compare that a little bit to what you see maybe on the side of the focus where you see a little bit of shearing. And we think that the neurons are probably responding to both, although it's not totally clear one of them has a bigger response versus the other. In addition to the pressure wave itself, what we also have is a radiation force. What's going on there is that the ultrasound will cause the tissue to move a little bit away from the transducer. That's because it absorbs momentum and it moves a little bit on the order of microns similar to the particle motion, that little bit of movement, again, causes some strains on the tissue. So those are the types of motions, very small motions, having an effect on the ion channel.

Nicholas Weiler:

And a micron is a millionth of a meter for those of us who are metric-challenged. Is that right?

Kim Butts Pauly:

That's right.

Nicholas Weiler:

So there you've got these tiny, tiny movements. And I think the other thing to reiterate, I loved how you said this earlier. You've got a hockey puck, basically a speaker up against the skull. You focus it down to the size of a jelly bean somewhere inside the brain. This puts me in mind of this installation at the Exploratorium in San Francisco where they've got these two chairs, they're almost thrones, that are maybe 20, 30 meters apart. They're quite across this courtyard from each other, and they've got these big concave backs to them. And what you can do is you can sit in one and your friend sits in the other one, and you can talk to each other at a normal volume without shouting, and no one in between can hear you.

But because of the way that the sound is focused by those concave discs, it's focusing your voice right on their head and their voice right on your head. And it sounds like something similar is going on here, where to get the kind of motion you need to stimulate a cell, or in your case Raag to release these drugs, it's only going to happen in that little focal spot that jelly bean and everywhere else, it's just going to pass through like I've got headphones on right now, and it's not stimulating my brain in the way we're talking about.

Raag Airan:

Yeah, just like you can focus light using optics, you can focus ultrasound using these acoustic transducers and lenses.

Nicholas Weiler:

So Raag for the applications you're developing, which is not stimulating brain cells per se. But the two things that I was hoping we could talk about were your work releasing drugs in particular spots, and then you also have work you're developing to do things like helping to flush toxins out of the brain. Again, I want to get into those applications in more detail in a few minutes, but in terms of how this actually works, we've heard a little bit about how we're tickling the neurons with these focused ultrasound beams. What is the ultrasound actually doing in your case to release drugs or to flush fluids through the brain?

Raag Airan:

So I'll first talk about the drug delivery and release. So with that idea in mind that we wanted to use ultrasound to target the delivery of drugs to different areas of the body of the brain, we have developed now two different ultrasound-sensitive nanomaterials that can be loaded with the drug. And then drug release is induced by ultrasound. In each of these systems it's a mechanical type mode of action. So by these pressure waves causing oscillations or thermally by heating up, and for reasons we don't necessarily want to heat shock the brain, or it's also physically difficult to heat in certain parts of the skull. We wanted to have a mechanical type response, and we've been able to develop two different drug-loaded nanoparticle systems that indeed release their drug cargo with ultrasound activation.

The idea is eventually a patient in whatever clinical setting gets an intravenous infusion of the drug-loaded particles, those swim in the bloodstream, and absent a stroke, every part of the brain has a certain blood volume. The drug would then be released from the particles where ultrasound is applied to that region of the brain in that blood volume. And then those drugs can cross into the brain like they normally would. So it took several years to validate that this system works in vitro and then in vivo. And we're now fortunate to knock on wood, be at the cusp of starting our first-in-human trial with the system to target delivery of ketamine, which is an anesthetic and analgesic also now FDA-approved antidepressant, but also a drug of abuse.

Each of those actions, the sedative dissociative actions of it, the abusable actions of it are certainly things that we might not necessarily want in a treatment of mental health disorder. So the idea here is if we target a particular brain region, the dorsal anterior cingulate that is hypothesized that that would be effective in treating the affective component of chronic pain without opioids or anything else involved. And so yeah, that's the trial that we are on track to initiate before the end of the calendar year, thinking in the October, November timeframe.

Nicholas Weiler:

I want to come back to that again in a little bit, but just to make sure I'm understanding, you basically have these little bubbles essentially, that have the drug in them. The drug is sort of in these nanomaterial bubbles.

Raag Airan:

Yeah. But bubbles is a triggering word for us.

Nicholas Weiler:

Bubbles is a trigger word. Okay.

Raag Airan:

Yeah. So we have their liquid phase nano droplets.

Nicholas Weiler:

So it's more like oil and water kind of thing.

Raag Airan:

Exactly. And the droplets will oscillate in the ultrasound field. That oscillation then induces permeability of the membrane that holds the drug inside, and then that allows the drug to release.

Nicholas Weiler:

So that's a great transition because I'd really like to switch to talking about where this technology is, where this is in development, and what are the most impactful, most immediate applications that the field is working towards and that you each are working towards in your respective areas. And Kim, this brings me back a little bit to that question of the comparison with transcranial magnetic stimulation that you were bringing up, which is that's out there, it's been FDA approved for certain conditions, it's in clinics. As far as I understand, ultrasound is much more in that transition from the lab to hopefully clinical trials either now or in the near future. So what is the thing that ultrasound is going to enable us to do with patients clinically, and what do you think the first big use case will be?

Kim Butts Pauly:

Yeah, that's great. One of the things I think is a little bit more clear is that it seems that it's easier to quiet down neurons. When you think about cases where there's maybe overactivity epilepsy, for example. So there's a nice clinical trial going on at the Brigham where they're applying ultrasound to the case of temporal lobe epilepsy. And then they are finding some, although it's just an initial safety result, that there is a decrease in seizures over multiple months. Another case where there's maybe just what you want to do is quiet down the neurons is addiction, where maybe just quieting down the nucleus accumbens is something that could be very beneficial. So there are clinical trials in a number of different places there. There's one in West Virginia, there's one that's going on in the UK, for example. Those are, I think, the low-hanging fruit in terms of good applications for this deep in the brain, small focal spots being able to really have a positive impact when we're just going to quiet down the neurons.

Nicholas Weiler:

Great. That's really helpful in understanding. And yeah, you mentioned the nucleus accumbens that's come up a few times on the show when we've been talking about addiction or when we've been talking about reward circuitry. As you mentioned, that's a structure that's fairly deep in the brain. It's not the deepest part of the brain, but it's down there. It's buried in there a little bit. Would you say that's something that it would likely be a little bit difficult to access with something like transcranial magnetic stimulation?

Kim Butts Pauly:

Yeah, I think so. Raag, do you want to comment on that?

Raag Airan:

Yeah. So the best we can model and tell is that the field that you get with transcranial magnetic stimulation, it's several centimeters wide, so maybe a small orange wide, but the field itself only goes about four or five millimeters deep into the tissue. So half a centimeter, just the jelly bean.

Nicholas Weiler:

Right. So a lot of it is for stimulating the outer layer, the cortical layers of the brain, which is a lot. It's a lot of important stuff, but there's plenty buried deep down, particularly at the emotion regulation kinds of things.

Raag Airan:

And then a lot of the data that we have from say, the animal models that we might use to better understand these processes are the best information we're getting is about those subcortical structures. So a lot of our neuroscientific understanding is based on what the nucleus accumbens or the hippocampus or the amygdala, et cetera, are doing. Fortunately or unfortunately for us, those are all at the deepest, most central portions of the brain. They're not on the surface that TMS can access.

Nicholas Weiler:

So you were mentioning these clinical trials that are getting up and running, and in your lab, you're doing some really foundational work to set the stage for these to understand the parameters that are going to be needed. What do you see as the big challenge that needs to be overcome to get this technology for brain stimulation specifically into the clinic and into patients?

Kim Butts Pauly:

Yeah, I think understanding it a little bit better. So we've talked a little bit about the strains, but then it seems that depending on how you apply your parameters, whether you apply all your energy at once or you spread your energy out, that you could have a different effect on the brain, whether you're stimulating or more quieting down. And so trying to understand that in addition, it's entirely possible that the number of ion channels and types of ion channels are different in every part of the brain. So it's almost like there's this huge parameter space of understanding how do you apply it for that particular part of the brain, and how do those interact?

Nicholas Weiler:

Because the brain is not a perfect sphere.

Kim Butts Pauly:

Yeah. And so you raise a whole nother question we haven't touched on yet, which is one of the difficulties with ultrasound is that as it crosses the skull, because the speed of sound is different than in the brain, it doesn't focus well at the point. So it defocuses and it's what's called aberrated, and there's a fair amount of work to compensate for that. And you have to have a transducer so that your hockey puck is divided into multiple elements, and then you can control them individually, and then you can precompensate for the aberrations and then really get a nice focus. But it's how you do that optimally and how you do that in a clinical setting where you don't have a lot of time and you have a patient in front of you and you want to get that information very quickly. Those are still to be optimized.

Nicholas Weiler:

Okay. Raag, so you mentioned that you're working on releasing ketamine locally. We've talked before on the show about ketamine as this very promising treatment for a number of psychiatric conditions. It's a dissociative anesthetic, but it has a whole complex array of effects. So you'd like to release that very locally. You're working on that. You've got some evidence that you can get that working in rodents. What do you see as the big next step for taking this to the clinic?

Raag Airan:

Yeah, I mean, our next step is to take it to the clinic. We're fortunate to be funded by the NIH HEAL Initiative to dot all the Is and cross all the Ts that we would need to do that. We've already contracted with a pharmaceutical manufacturer in New Jersey to make our formulation to pharmaceutical standards that is actually being tested in formal safety and toxicologic animal studies right now with that data. And we anticipate submitting that IMD and the regulatory paperwork over the summer so that we can begin this in the fall.

Nicholas Weiler:

Oh, fantastic.

Raag Airan:

I want to emphasize that the focused ultrasound by far is not like a thing far from the clinic. We have multiple systems that can accomplish this transcranial ultrasound focusing at Stanford. And so this year we plan to be involved in three different transcranial focused ultrasound clinical trials with each of three different manufacturer systems. These things are real. They're here, they're present, and now we need to figure out how to best use them. So one trial is that the local ketamine delivery to the dorsal anterior cingulate in patients with chronic pain. We hope to open that in the fall. Another trial is a version of that epilepsy neuromodulatory trial that Kim mentioned. Similar endpoints, a slightly different protocol.

This is with Bob Fisher, our head epileptologist. We already identified the first, or Bob has already identified the first patient. And we're working out the logistics to start the neuromodulation next month. A third trial, which we're fortunate to have just received the award from Knight Initiative at Wu Tsai to try to translate the phenomenon that our lab has described, where we seem to be able to use a similar low-intensity focused ultrasound protocol to neuromodulation. But instead, what we observe is happening in the brain is that we're upregulating the movement of fluid in and around the brain and through the brain, the so-called glymphatic system, which is a term that describes how the cerebrospinal fluid, the fluid that bathes the brain and the spinal cord exchanges with the interstitial fluid, the fluid inside the actual meat of the brain in the spinal cord.

Nicholas Weiler:

Sort of the wash cycle of the brain people think.

Raag Airan:

Exactly. We seem to be able to use this low-intensity focused ultrasound protocol to upregulate that system if you will. We've seen in rodent models that we could use this to get better delivery of tracers from the CSF compartment into the brain. But more recently and potentially more exciting, we can actually clear the brain of junk in using this system. A star neurosciences student who's now a first-year medical student here, Mateen Nizadian, this was his thesis. He in two different animal models of intracranial hemorrhage, one where the blood was around the brain and one in which the blood was actually in the brain in the meat of the brain. And in both cases, applying this protocol, he was able to clear the blood mostly from the brain. It then came out into the body's lymphatic system that was associated with lowered neuroinflammation, lowered brain edema, increased recovery of functional measures like motor grip, et cetera, and lowered mortality in these mouse models.

Nicholas Weiler:

So this is a test case essentially of a form of stroke where you're able to clear some of that pressure, clear the blood that's leaking around or into the brain. And so if I understand you correctly, what you're proposing is, one, this could be a great treatment for a stroke. And two, this is also a proof of concept that you could help move some fluids into the brain if you want to, for example, have a tracer to show where there's buildup of toxic amyloid protein. If you're trying to determine if someone might be at risk for Alzheimer's disease, and B, maybe you can by doing this gentle stirring of the fluids that bathe the brain, maybe you could help the brain clear away some of those toxins.

So these are very exciting applications of this technology and so wide-ranging from very gently adjusting the sensitivity of brain cells and neural circuits in psychiatric or neurological disorders to releasing drugs in particular places so that they are just doing the things you want them to do in the places you want them to do. It's almost like this invisible hand, this invisible surgical tool that you could use to help the brain clear away junk or get a tracer into the place that you want it. This is a very, very exciting area of research, and I'm so glad that you both have been able to come on the show and tell us about it. I really hope that we can have you come on again and talk in more detail about some of the latest and greatest applications you've been developing.

Kim Butts Pauly:

Oh, super. Thank you so much for having us.

Raag Airan:

Yeah, thanks so much, Nick.

Nicholas Weiler:

Thanks again so much to our guests, Kim Butts Pauly and Raag Airan. To read more about their work check out the links in the show notes. Coming up on the show we'll be diving into a revolution that has transformed neuroscience over the past few decades. One centered right here at Stanford that fundamentally changed our understanding of which brain cells matter for understanding how the brain works.

Brad Zuchero:

I sort of liken it to a Renaissance sculptor, quarrying out a giant block of marble and then sculpting it down to Michelangelo's David or something, right? I mean, this is the way that development works, especially in the nervous system.

Nicholas Weiler:

Don't miss this and other upcoming conversations from the frontiers of neuroscience subscribe or follow the show on your podcast platform of choice. And if you're enjoying these conversations, please help us spread the word and bring more listeners to the frontiers of neuroscience. 

As always, we'd also love to hear from you. Leave us a comment on your favorite podcast platform, or send us an email at neuronspodcast@stanford.edu. 

From Our Neurons to Yours is produced by Michael Osborne at 14th Street Studios with production assistance from Morgan Honecker. I'm Nicholas Weiler. Until next time.

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