Imagine a world where you have a new sense, an extra sixth sense, if you will. And no, I'm not talking about the movies.

I see dead people.

Longtime listeners of this podcast know that I'm a big fan of Halloween. But what I'm talking about today is different. It isn't supernatural. It isn't science fiction.

The interest in my lab for a long time has been what if we could actually push information into the brain via an unusual sensory channel and repair lost senses or build new ones?

That's David Eagleman. He's a neuroscientist, adjunct professor at Stanford, author and co-founder of the California based tech company Neosensory. And he says there's a way to actually give humans entirely new senses, as well as repair lost senses, all with the help of technology. Imagine this a wristband that helps those without hearing communicate by feeling sound. Or, a vibrating belt that gives you a better sense of direction, letting you feel which way is north or south. Maybe even hooking yourself up to a device that feeds you data on the rise and fall of the stock market or Twitter trends in real time. Think about all of that and how much our lives might change. So get ready to take a peek into David's vision of the future and reimagine the way you sense the world. I'm Dr. Sanjay Gupta, CNN's chief medical correspondent, and it's time to start Chasing Life. This isn't my first time talking to David Eagleman. Our paths have crossed a few times because we have this shared love of the brain. And I have to tell you that each time I've spoken to David, I've always been struck by what a creative thinker he is. He's a neuroscientist, but not just that. He's also a bestselling author. He even worked as a scientific advisor for the hit HBO sci-fi television show Westworld.

I designed every part of this place. It's not a theme park, but in the entire world.

The way I like to put it is that David just thinks about the way that our minds operate and perceive reality in a really interesting way.

I've just always been super interested in how the brain, which is locked in silence and darkness, constructs reality. And, you know, we've got all these little tiny windows that we come equipped with, like to pick up photons with our eyes or picking up air compression waves with our ears or mixtures of molecules with our nose and stuff like that. But fundamentally, all the brain has are these signals running around these little voltage spikes in the neurons, and it has to construct your reality that way. And so what I started wondering about a long time ago is: could you actually feed information into the brain via an unusual channel, and would the brain figure out what to do with it? Because the brain's whole job really is just to figure out what is relevant, what is important out there, and what it can act on.

You know, I have to tell you, this is a bit of a side note. I recently read Ed Young's book, "An Immense World," and it was so funny because I listened to your TED Talk from 2015, actually, o seven years ago. And you were talking about umvelt back in that talk, which is something I don't know if you've read Ed's book yet. It's, it's, it's going to sound very familiar.

Yes.

But this idea that every creature has its own envelope. Explain to us, what does that mean? How do you describe that?

Yeah. So this was originally described in 1909 by a biologist who was interested in the fact that all creatures pick up on different sorts of signals. So in the blind and deaf world of the tick, all it's picking up on is temperature and butyric acid, which is body odor of animals. That's its only signal on the world. And so the question is, what is reality like for a tick or for the blind echo locating bat? It just picks up on echolocation returning to it and it has to construct its world from those signals. So the umvelt is the part of the world that you see and everything else you don't see. That's part of the wider reality. But the thing that's always been interesting to me is that there's really no reason for us or any animal to ever stop to consider that the world is wider than what you can observe. And so we all essentially assume that we're seeing all of reality, even though we know now that, you know, we're seeing just a tiny, tiny fraction of it.

It's a fascinating idea. And, you know, it raises so many questions. I mean, we think about our senses, the way that we think about it's what we know. It's our umvelt. Do we have the capacity to sense the world in other ways? Do our brains have that capacity to do that? And if so, why haven't we evolved to do some of those things? Why don't we like a sea turtle sense electromagnetic waves, if we potentially could do that?

It turns out we can. My interest is in building new ways of getting information in, so we might actually be able to build new qualia and understand what that is like. But I should say qualia is the subjective experience of a sense. So for example, when a neuroscientist looks at vision, you know, it's all this activity in cells. And yet, vision doesn't feel that way to you. It feels like, oh, look at that lovely orange and red sunset or, you know, the taste of cinnamon on your mouth or the smell of a campfire or something. These are qualia. It's your subjective experience, even though physically you just see spikes running around in the brain. And so the question is, could we have a new kind of qualia that is not something that we're used to getting through our eyes or ears or nose or mouth, things like that. In the same way that I can't imagine a new color, could I imagine or come to develop a new qualia. And so the interest in my lab for a long time has been what if we could actually push information into the brain via an unusual sensory channel and repair lost senses or build new ones?

David believes that just because humans haven't evolved to have certain senses, such as magnetoreception or night vision, that doesn't mean that they are necessarily out of our reach. He believes that we can expand our own vault. In fact, there are many people lacking a sense, such as sight or hearing, who have then discovered ways to adapt or experience those senses in a different way. Think of Braille as a really basic example of this. In a way, you're basically using touch to see letters, to read. That's a concept that's been around for a while. It's called sensory substitution. David defines this as basically building a device that feeds the information your brain would usually use for a sense through an unusual or a different channel.

In 1969, there was a scientist named Paul Bach-y-Rita, who was the guy who really pioneered this. He took blind people and put them in a modified dentist's chair where on the back was this little grid of solenoids, these little things that poke in and out at you. And so what he would do is he took a video camera, and whatever the video camera was seeing, you would feel that poked into your back. So if you put a telephone in front of the camera, you feel the shape of a telephone in your back. Or you put a face, you feel the shape of the face poked into your back. And blind people got really good at being able to identify what was in front of the camera, just based on what they were feeling on their skin, on their lower back, which is bizarre. But remember, all vision ever is, is spikes running around in the brain. We're used to photons coming in these two spheres in the front of our head and then getting converted to spikes. We think that's pretty sensible, but it's just the same. It doesn't matter how you get it in there. We can't ever know if it's exactly the same. Look, truth is, I can't know what vision is like for you or you for me. You can't know what the qualia is like for anybody else other than yourself. But yes, somehow they were able to recreate this and be able to see through their back.

As I mentioned earlier, back in 2015, David gave a pretty popular TED Talk. Today, it has more than 3.4 million views. Now, during this talk, he unveiled an invention of his own that used sensory substitution to help people with hearing loss feel sound.

So it's a vest with all these little motors and it's all vibratory motors. And we can translate, for example, sound into patterns of vibration on the skin. And we do this for people who have severe or profound deafness. What we're doing is we are taking what the inner ear normally does, which is the inner ear, you know, captures the sound from the eardrum and breaks it into frequencies from low to high and ships that off to the brain. We're now just putting that on the torso. So the torso is now capturing that information. You have these little motors that tell different spots of your skin, "hey, there's high frequency, low frequency and so on." And that goes up your spinal cord into your brain. And what we were able to demonstrate is that people who are deaf became able to hear through this method of sensory substitution because the brain doesn't really care where the information comes from, as long as it gets the info and it can correlated it with, let's say, seeing somebody's mouth move or, you know, you're knocking on the door or you're clapping your hands or whatever, as long as you can correlate that, then it puts together "ah, that is sound." And the really weird part is that people, after about five or six months, describe this as hearing. So I say, "what is it like for you when, you know, when you see the dog bark? Do you feel like, oh, there's vibration on my skin and it must be that it's a dog barking?" And they say "No, I just hear the dog bark." And I say, "Well, what do you mean do you hear it? Like, do you feel like you feel the stuff on your skin?" They say, "No. I hear the dog barks out there."

In that video. I remember there was this example of one of your graduate students covering his mouth so that the person who is deaf could not see his lips. And then he was saying a word, and based on the vest, which it's an acronym for something, remind us what it's an acronym for?

Versatile extra sensory transducer.

Okay. It's a good acronym. So he's wearing this vest. The person covers their mouth, says a word. And then using this vest, they're able to discern what that word is. And I think I even remember the word was "where," as in where are you?

Where...where....

How does that work, David? I mean, I get the dog barking thing and the vibration. But a word like that, no lip reading going on here. Do you have to create a language for the vest?

So here's the thing. When I say the word "where" on your podcast and the listener hears it, what's happening is there's different frequencies. There's high frequency, low medium things are going. Up and down. That's how it's represented. It's just a soundwave that hits the listeners ear, the inner ear, the cochlea breaks that up from high, low frequency, and that goes off to the brain. And they have come to learn that particular signature is the word "where." And of course, if they speak different languages, it's a different signature of ups and downs of frequencies and so on. It's exactly the same thing with the vest. It's highs and lows and mediums. And Jonathan, who happened to be the participant in that video, learns, "Oh, okay when it goes like this pattern on the vest, that is the word 'where.' And this other pattern is so and so." But it's not that he's memorizing individual words, it's that he's learning how to listen with the vest in the same way that when you as a child are learning vocabulary, it's not that you're memorizing just the ups and downs individually of each word. You're learning generally how to hear, how to understand words. So even if I say a new word like schmegeggi, you understand how to hear it.

How quickly does the brain adapt or be able to understand, if you will, the language of the vest?

Yeah, so it totally depends on the application. So in the case of hearing, we test people on day one and right away people do a little bit better than chance performance on tests of, let's say, identifying sounds or distinguishing sounds from one another. And then it just goes up at a shallow slope. It just goes up every day. So after about a week, people say, "Oh yeah, I can totally understand the difference. And my two children are talking. I can tell whose voices." And after a couple weeks they say, "I can tell the difference between my dogs barking, you know, I can really distinguish that. And then after a while, they're, you know, they're just getting better and better at language and details and understanding things that they didn't even know made sound like, Oh, I didn't know, microwaves, beeped or whatever." They've just become better and better at it.

Now, after David gave that TED talk, he took the same technology used to make the vest and created a wristband. It was the same concept, but it was just smaller and easier to wear. He also started his own company called Neosensory, which creates and sells sensory substitution devices. And I do want to note this: there are many sensory substitution devices out there, and David isn't the only one who's actually developing them. There's a technology, for example, called Brainport that allows people who are visually impaired to see in a different way using a sensor and electrical stimulation on their tongues. And there's also the vOICe. That's a device which also helps those who are visually impaired. It kind of looks like a pair of sunglasses. But the thing is that David wants to take all of this a step further. He wants to use similar technology to augment or add to our senses.

There's always this fine line that you discover when you're looking at how to, let's say, replace a lost sense like hearing. And you realize at some point, wait, I could just add better hearing. I could do superhuman hearing.

We have that coming up after the break.

And now back to Chasing Life and more of my conversation with neuroscientist David Eagleman.

I get the sense from talk -- I get the idea from hearing your talks that you draw some inspiration from the animal world. But how did it begin, though? This idea of not sensory substitution, but new senses?

There's always this fine line that you discover when you're looking at how to, let's say, replace a lost sense like hearing. And you realize at some point, wait, I could just add better hearing. I could do superhuman hearing. But, you know, this is everything. Like if you're making a prosthetic leg and at some point you realize, wow, I can actually make a better leg than we have evolved to have or so on. So yeah, that's what got me really interested in this idea about sensory expansion and addition.

Are you solving a problem by delving into this area?

We actually have 70 projects going on now. Seven zero, different projects in the company about adding senses. One thing that I'm really interested in is I want to reduce friendly fire in the military. And so imagine you're wearing the vest and you can feel, "oh, Steve is 500 yards on my right." Even though he's on the other side of the wall, I know he's there because I can feel him. And you can feel the location of everyone around you so you don't accidentally shoot your colleagues. You know, this kind of thing is stuff we've been experimenting with. We've been doing this with blind people as well, people who are blind, the same idea where they can feel everything that's going on around them. And by the way, this in some sense is better than normal vision because, you know, you can feel when someone is walking towards you and then walking around behind you. And on top of that, we can add navigation directions where we say, "okay, you've never been in our offices before, but I'm going to give you directions to this conference room, so go straight." And they feel a buzz in their front and then, "oh, okay, now turn right." You know, they feel a buzz on their right. "Okay, now go diagonally here." They feel the buzz diagonally over there. And that's yeah, they can navigate around somewhere they've never been before.

Would I be somebody who do you think would benefit from wearing the wristband? Let's say I turn the amplitude really low, so I'm catching things that I otherwise would not hear. Is there benefit for someone like me?

So there may be. It depends what kind of things you're interested in if you want to pick up on....

I don't know what I'm interested in. I'm just interested in experiencing the world differently or more fully, I guess, you know, I'll make it up. I want to hear tiptoeing down the hallway of my kids have when they're sneaking into the house at night. Hopefully they're not listening to this right now, but I'm just, you know, making it up. But just if I were to do that and let's say I just wanted to order this thing and play around with it, would you recommend that? Would my life change, do you think?

Oh, I certainly think so. It depends what it is you're trying to get. But the reason we have 70 different experiments going on is because this is all experimentation, figuring out what is relevant for people. I'll just give you one other example. I was wearing an infrared version of the band, but it wasn't in the temperature range, it was in the near infrared range. Anyway, I was walking along and I suddenly felt, "who, there's a lot of near infrared coming from somewhere." So this was in the dark and I was between two houses and so I just followed my wrist and I found it was a security camera that was set up with infrared lights and a camera, normally completely invisible to you in the dark. But it was totally obvious to me that it was there. Now, that might not be useful to you. It would be useful to have somebody involved in security or whatever. But I just think there's so much of the world that surrounds us to be discovered. And what we know of the world is so tiny. We've essentially built this pier out into the ocean of the unknown, and most science is yet to be done. I mean, despite our big fat textbooks in the field and the way that scientists speak as though we've figured everything out, we've figured almost nothing out. And so I just think it's a terrific new tool to directly be plugged into other signals in the world around us.

How many do you imagine we could have? I mean, if we think of five senses, there's far more than five senses. We have thermoreception and all these other things. How many do you think we potentially could have? How many senses, I guess?

So. It turns out that, you know, the brain is really good at distributing its real estate so that it can incorporate new data and new talents and so on. So if you learn how to swim and you learn how to play chess and you learn how to do Sudoku or whatever, it doesn't. These things don't fight each other, but they all manage to to share the same real estate. So I have a strong suspicion that we'll be able to add new senses quite easily and the brain will make room. But the point is that we can add more and more and more. So I don't know, by the time we get to the 10th sense, maybe your vision will start getting a little bit blurry and the 12th sense, maybe, you know, you won't be able to hear quite as well. But it's not a matter of shoving things out. It's just a matter of sharing the real estate until things start getting really tight. Anyway, I have a suspicion that with the technology that we've been developing in my lab, we'll be able to add, you know, let's say ultrasonic hearing and infrared and, you know, stock market and drone and so on. And your brain will figure out how to incorporate all of these and presumably have a different qualia with each of them.

Do you think about any potential downsides? You mentioned that there could be, you know, blurriness of vision if we overload too many senses into the brain? Is that a real thing or were you just sort of saying that? I mean, could we have sensory overload, so to speak?

The weird part is we just get used to whatever senses we have. And what we have are these attentional mechanisms that are very good at attending various things. So for example, if I ask you what your shoe on your left foot feels like to you right now, you can actually pay attention to that and suddenly feel from it. But it wasn't overwhelming you or anything like that, even though that's been sending signals up to your brain this whole time. So what that indicates is you can have lots of information available and your attentional systems just go where they need to at any given time. So I don't actually think that people will get overwhelmed with having more senses. And, you know, we live in worlds where we're surrounded by screens and headphones and whatever. And, you know, if you start feeling overwhelmed, you just take it off and relax. I think it's the same thing there.

What is the future or a successful future for David Eagleman and Neosensory look like? Do you think that there's a lot of, again, people who don't necessarily have loss of particular senses, but are using these devices to expand senses, maybe up to 70 of them, if I heard you correctly earlier, to live a better life? To live a more efficient life? How do you think about it?

Yeah. I mean, the main thing that we're doing, which is unbelievably satisfying to me, is we are helping people with hearing problems. That's been the main thing that we've been after as a company. So all these things with deafness, with tinnitus, with high frequency hearing loss, we're able to change what people are able to do about this. And that by itself is enormously satisfying and that would be enough. But I'm also very interested in what is the brain capable of in terms of bringing in new senses and what could it do? Where could humans go? There's a sense in which this is the trajectory our species has been on from the beginning, which is, "Hey, let's build the Industrial Revolution and let's build the Internet and let's, you know, be tied into the entirety of humankind's knowledge with a rectangle in my pocket and so on." You know, we're constantly ratcheting things up. And now I think this is the next step is understanding how do you want to experience the universe around you and what would it be like to tap into these other signals that are surrounding you but are invisible to you?

You're an inspiring dude, I got to tell you. I think about things differently every time I'm lucky enough to spend some time with you. It's really fascinating. And I'm not kidding, I feel like I'm a good beta sort of person. So I'm going to go to your I'm going to order one of these and I'm going to try the different applications and just I'm going to walk into it not knowing what I don't know and just see what comes of it. And then I'll send you an email and I'll tell you what I've humbly learned.

Terrific. I can't wait.

You know, I'm not kidding. This conversation with David really has me thinking about my senses in an entirely new way, and I can't wait to see what else he learns in his lab. You know, maybe in the future, we're going to live in a world where new senses help us live happier, maybe healthier lives. And in the meantime, I'm glad David's technology has been helpful for those who are currently missing a sense. I am curious to hear what you think of today's episode. If you could have any sense in the world, what would it be? Or are you someone who would like to stick with the senses you have, or maybe make those senses even better? Let me know. Record your thoughts as a voice memo. Email them to asksanjay@cnn.com or give us a call at 470-396-0832 and leave a message. We might even include them on an upcoming episode of the podcast.

And speaking of super senses, I did want to share a call that we received in response to my conversation earlier this season with Ed Yong. As I mentioned, I had talked to Ed about the concept of umvelt, particularly in the animal world. And Ed talked to me about the importance of understanding other animals umvelt, like a dog's need to smell while on walks. Well, turns out I'd been walking my dog wrong all this time, and I'm not alone.

My experience walking my dog has become a totally different experience. Like you, I thought, okay, we have a goal. We get our steps in. Well, now I allow him as much time as he needs to sniff. It has become a meditative experience for me. And that tension that I was carrying with that task has been relieved. Thank you. And my dog thanks you.

I am glad to hear this advice helped others, including dogs as well. Please keep the calls and the voice memos coming. I really do love hearing from you all. And we'll be back next Tuesday with an episode about sensory processing disorder -- when what you feel is too much, too little or just plain confusing. Thanks for listening.

Chasing Life is a production of CNN Audio. Our podcast is produced by Emily Liu, Grace Walker, Xavier Lopez, Eryn Mathewson and Andrea Kane. Our intern is Amber Alesawy. Haley Thomas is our senior producer and Abbie Fentress-Swanson is our executive producer. Tommy Bazarian is our engineer. And a special thanks to Ben Tinker, Amanda Sealy and Nadia Kounang of CNN Health.