 Hello everybody, I'm very pleased to be here. So I'm a neuroscientist and a psychiatrist, and I'm going to tell you a little bit about some of the work that we do in my lab. Very basically, we study the heart-brain connection and how that relates to this process called interception. So in my talk, what I'm going to go over today is give you an introduction to what is interception, what's the history on it. I'm going to talk a little bit about the heart-brain connection and how I studied that in the past, because I think it sets up very nicely the studies that we're doing right now with the float experience. And then I'll talk a little bit about some of our preliminary findings that suggest perhaps floating may be a form of sensory enhancement. So what is interception? I don't know if any of you have heard of that term before. Very basically, you can think of it as how the brain senses the inner body. And we owe this term to a gentleman by the name of Sir Charles Sherrington. He was a British physiologist. See back in 1906, he actually coined the term interception. And he did this because he was thinking about the nervous system. He actually won the Nobel Prize in 1936 for a lot of his work. And one of the things, he was a very careful thinker, and one of the things that he thought about was how do all the sensory signals that are available to the brain become received? And he sort of looked at the brain and he looked at the body. And he sort of divided it up. So he talked about a process of extraception, so how information from the external world gets in, lights, sounds, kind of how I'm seeing the audience now. He also talked about proprioception, so how information about the body and space gets received by the brain, kind of like how I'm moving my arms now. And then he talked about interception, really how the brain senses the inner body. So when you think about interception more in a more detailed way, there's a lot of systems or channels used by the brain to sense the inner body, okay? Here's some examples. So we have the cardiovascular system. We have the respiratory system, gastrointestinal sensations, hunger, thirst, itch. There's a whole host of them. And you can see just from looking at them that they're very different. Each of them have different types of sensory experiences associated with them. Some of them seem more mechanical. Some of them like pH and glucose are more chemical in nature. And you can even see that some of them can have a component of pain, so angina is chest pain. That can be a signal of something like a heart attack. Also you can have non-painful cardiac sensations, palpitations. And sometimes that can be a sign of a cardiac injury. It can also be a sign of another condition in psychiatry like an anxiety disorder, okay? Now I'm showing you all of these sensory channels in a very clear way as if we can all feel these things and report on them in a very precise way. But the reality is it kind of looks like this. So the brain receives all this information all at once and is it really even a good idea for you to have awareness of all of these sensations at the time you're sitting here. We'd prefer that it looks sort of like this, right? But that's not actually the case, okay? And there are prominent reasons for that. Now the history of interception search is actually a little bit varied. So we surveyed recently all the articles on the topic of interception that have been published. And this is what we found. So basically since Sherrington coined the term, there was kind of a dead zone for a while. And then there was some fluctuation and some interest in the middle part of the latter century, a little bit of an increase, but what you can see is right now we're currently undergoing an explosion of interest in this research area. I'm going to talk a little bit about one study in particular that I've done for a couple reasons. One is that it sets up very nicely the approach to studying floatation and also the way that I think about it, but also because it illustrates something very nicely in terms of where I did my training with Daniel Trinnell and also the collaborators that I've had over the years and Justin has been one of the rock study collaborators in this effort. So how do we study the heart-brain connection? I talked with you about heartbeat sensations as one example. I gave you some examples where the heartbeat sensation was very prominent. And for a variety of reasons, some of which I'll explain later on in my talk. We use a method where we can provide experience of heartbeat sensations that's fairly prominent. As I said, I'm a physician. And so we have the ability to use a very potent medicine called isopraterinol. Now isopraterinol, even though it's a weird-looking word, is something that you all intuitively have experienced in one way or another because it's a fast-acting medicine that stimulates receptors on the heart and in the lungs that are activated by epinephrine or adrenaline as it's known. So if you think about times in your life where you felt your adrenaline going, that's kind of what isopraterinol feels like. The nice thing about it is that you have a lot of experimental control. And in science, like I said, with those spaghetti plots, we really want to be able to systematically narrow down and study each channel of interception very discreetly. So this is how we did it in the past. I developed a method where we infuse isopraterinol intravenously. Here you can see it times zero. So that's when the infusion starts. And this is about a two-minute window here. And you can see that on the y-axis we have the heart rate. The normal heart rate ranges between 60 and 100 beats a minute. The solid black line here, just that's the only one to pay attention to really, is the heart rate response. And you can see that after you infuse a very low dose of this medicine, not much changes in the heart rate. Now, when you increase the dose, what you can see is that the heart rate response reliably increases. Now, the way that we study interception in this context of heartbeat sensations, it may not come through very clearly here, but there's a little dashed line that I want you to look at now. Now, this line is a dial that individuals turn to rate their experience of their heartbeat sensations in real time. So they turn the dial up if they notice an increase in the sensation. The amount of the increase gives you a measure of the intensity of the sensation. And then what you can see is that at increasing doses, there seems to be a relationship between the heart rate response and the dial response, okay? And that can be quantified. So in this particular study, our hypothesis really is that interceptive awareness of heartbeat sensations is mediated by a pathway leading to a brain structure called the insular cortex. I'm not going to describe the insular cortex in great detail other than to say that it is the most prominent area that we think represents internal body sensations. My colleague, Dr. Kyle Simmons, is going to give his talk next, and he'll go into that in much more detail, so you'll really have a full understanding. But for this study, we thought that at this point, the insula was probably the most responsible region of the brain for feeling internal sensations of the heartbeat. And so what we decided to do was to study that pathway, study somebody who had experienced injury to that pathway, okay? And the way we did that was we studied a very rare patient with a form of neurological injury. The patient's name was Roger, and he acquired a viral infection in the 1980s, early 1980s. This was before some of the later antiviral medications had developed, and the virus that he contracted was a herpes encephalitis virus. And in a subset of patients, that virus can cross the blood-brain barrier and it can actually damage the brain. Now what was very interesting about Roger is that it damaged a variety of areas, but most notably for us, given our interest in research, this is where the insula would be, and what you can see is that it's almost completely gone on both sides of the brain, okay? So it really provided a unique opportunity to conclusively study what happens in a person who doesn't have an insula. How do they feel their heartbeat sensations? So to do that, we brought Roger in and we gave him isopraterinol and some healthy participants who consented to the research. And this is what we found, essentially showing that as we gave increasing doses, this is actually twice the dose of the highest one that I showed you before. These are the most common ranges of doses that have been used in this kind of research, which has gone on in human participants safely for over 40 years. So it's not like we were taking something new or applying this method in a new way, this has been around for 40 years. And what you can see is that Roger's heart rate response is entirely in line with the healthy participants who were matched in terms of age, in terms of gender, and body mass index. So what did we find? Well, on the basis of this hypothesis that we have, we predicted that if the insula really is necessary for the ability to feel heartbeat sensations, he really should not have an increase in sensation of the heartbeat. So when we gave him the medicine, we actually looked, I'm gonna show you now the highest dose. So this is a little complicated, but let me show you. So this is time, so the infusion started right here. And here's the heart rate increase during the infusion. This light blue is the healthy comparison participants. You can see their heart rates increased. You can see in this green, Roger's heart rate increased. And what you can see for the healthy participants is they have an increase in their dial ratings. That's consistent with the increase in the heart rate. And what jumps out at you is at me is sort of two things. One is that Roger's heart rate response seems to be delayed. So it's a bit abnormal. But if you look at sort of in relation to the healthy comparisons, it's pretty equivalent. So this was surprising and very unexpected. I mentioned before that we could calculate Roger's accuracy with how he experienced heartbeat sensation. So this is if you calculate what's called a cross correlation between the dial and the heart rate. And when we did that with Roger, across a variety of different measures, which I won't bore you with the details, suffice to say that Roger was within the normal range on everything except for that time measure. Again, unexpected. One of the things that we're very interested in is what are the pathways by which the brain receives information from the heart? And given this finding where Roger clearly had some ability to feel his heartbeat sensations, we were wondering what could explain that. So we asked him where he felt his heartbeat and this is a cardiac body map. So these are the healthy comparisons. The brighter color here means that larger numbers of healthy comparisons felt the heartbeat sensation. You can see that Roger felt it in about the same location. So we wondered, well, can we maybe do something if that's where the sensation is, can we do something to attenuate that pathway? So the idea was maybe there's something in the skin that is helping Roger feel his heartbeat sensation. So this led to consideration of another hypothesis. Basically, the interceptive awareness of heartbeat sensations is mediated by two pathways, one projecting to the insula and another projecting to another body-sensitive brain region that's well-known and well-characterized that represents information from the skin, the somatosensory pathway. So the idea was what happens if both of those pathways are injured or attenuated, I should say, not injured. So in this follow-up, what we did is we studied Roger's feeling of his heartbeat again, but this time, both for him and the healthy comparison participants, we applied a topical anesthetic cream, like a lidocaine cream to the surface of the chest to see if attenuating skin sensation in the chest would have an effect on heartbeat sensation. And here's what we found. Anybody see any differences? So here we have the healthy comparison's heart rate response, here we have their dial rating, very consistent with before. Here we have Roger's heart rate response consistent with the comparison participants, and here's his dial rating, completely absent. He was told specifically, turn the dial up if you notice an increase in your heartbeat sensations. Now maybe he fell asleep, right? That's certainly quite possible. So what we did was we asked him and all I will say is I'm gonna skip this. Suffice to say that Roger was able to verbalize an experience of his heartbeat sensations and he did not have an experience of his heartbeat and this stood in contrast with her comparison participants. Okay? So this study provided some conclusions. One is that there's multiple pathways in the body and those multiple pathways can be utilized by the brain to receive information about the heart. And there's perhaps an inner pathway and an outer pathway. With respect to this outer pathway, it seems that the skin, which is a surface organ, is something that can communicate information about the heartbeat to the brain. And finally, one of the questions that we can't really address with this is whether or not there was some form of compensation in Roger. So he had this viral injury to his brain and it's possible that maybe he really couldn't feel his heartbeat sensations at all in the immediate aftermath, but we know that there's a lot of plasticity in the brain and we know there's reorganization following brain injury, so perhaps it's possible that the skin pathway is a compensatory one. We don't have the ability to make that conclusion with this study. Okay? So now I'm gonna switch gears a little bit and talk about why study floating. I think you may have seen this slide from Justin in previous years. The idea is that if you think about neuroanatomically, what floating the experience is like, you have the attenuation or reduction of various extraceptive and proprioceptive sensory signals that the body is transmitting and that the brain is receiving, okay? So this is not a lesion pathway per se, this is not something that reflects a pathological alteration, but it represents a sort of shift in the balance of these signals of it I think is interesting and worth studying. So the basic hypothesis that we have right now is that floating enhances interception, okay? So this is related to what some people prominently report in the float experience and one of our thoughts, which is a secondary hypothesis, is that perhaps altering the balance of input between interceptive, proprioceptive and extraceptive signals reaching the brain is responsible. So I'm gonna do a little demonstration and then I'll get to the float results, which I'm sure you've all been waiting for. So the first question I have for people is just a show of hands. How many of you have had a prominent experience of your heartbeat sensations while you were floating? Just raise your hands for me, okay? I think almost everybody. I think that's about 90%, okay? All right, so we're gonna do a little exercise together. So what I'd like you to do is with your eyes open and seated in comfortable position, just pay attention to the feeling of your heartbeat right now, okay? So when you're ready, go ahead and just notice the feeling, okay? Next thing that I'd like you to do is again, pay attention to your heartbeat, but this time, every time you feel it, I want you to silently count the number of beats that you feel, okay? Go ahead. The next thing that I'd like you to do is pay attention to the heartbeat. And instead of counting silently, every time you feel a heartbeat, just tap your finger on your thigh. Go ahead. Next, we're gonna imagine a different scenario. So now imagine you're in a room and you have either some headphones or you have access to a speaker. And what is gonna happen is you're gonna hear tones through the speaker and you're gonna have a number of trials and in some of the trials, you'll hear a tone in all of the trials. And in the first, in one set of trials, the tone happens at the same time as your heartbeat. So what I would ask you to imagine is if you just look at my hand and imagine that my hand is your heartbeat and the heartbeat goes like this, okay? So in half the trials, the tone is gonna happen at the same time as the heartbeat, just like this. Beep, beep, beep, beep, okay? In the other half of the trials, the tone is gonna be slightly delayed from your heartbeat, so your heartbeat's going along, but the tone is a little delayed. So beep, beep, beep, okay? And what I'm gonna ask you to do in that type of situation would be to pay attention to the heartbeat sensation that you feel and compare the sensation to the tones and tell me yes or no whether or not your heartbeat sensation's happening at the same time as the tones or at a different time, okay? Now, in this particular scenario, I can give you the tones that half the time occur at the same time as your heartbeat, half the times at another time, and we can do it a bunch of times. So for example, if you were right, we did 50 trials and you were right 40 of those times, that would be kind of like calling black 40 out of 50 times in the roulette table in Vegas and you would probably head straight to Vegas and start gambling, okay? So you can evaluate on an individual level how well somebody can feel their heartbeat sensation. The question is, how easy was that? And finally, you can also modulate the heartbeat. So what I'd like you to think about is just how easy is it? Well, using that sort of very complicated and onerous tone task, turns out most people can't even feel their heartbeat when they're at rest. The average is about 34%. This is true in a study we did with experienced meditation practitioners for multiple traditions. And what's interesting with respect to pathways is that even heart transplant patients who've had somebody else's heart inserted in their body to save their life and to preserve function, they feel their heartbeat at about the same rate. Now, everything that I just ran you through are what I call the facets of cardiac interception and that first task where you're just paying attention measures some of them and you can see that when you counted, we're measuring more, when you were tapping even more with heartbeat detection, we're getting more and then finally the infusion condition where you can really evaluate all the facets and it's one of the reasons I've used it. Kyle is gonna talk about the VIA or visceral interceptive attention task. It's a nice contrast. But the next question with floating really is how does floating alter the balance? So the first set of results that I'm gonna present relate to sessions one through three for the floating and this was a condition where we had eight participants in the chair condition, in the chair float and eight participants in the pool float, okay? And what we did is to look at interceptive intensities, we just asked people after each float, how intensely did you notice things like your heartbeat sensations, your breathing sensations, your stomach sensations? And so here are preliminary results. You can see that even after the first session, the group that is in the pool float has a much higher experience of the breathing and that's true across sessions one, two and three and in fact the group effect is statistically significant even in eight per group. What about heartbeat sensations? Well, a little bit of a different story here so far in this small sample. What we can see is that the intensity of heartbeat sensations is about even between the two groups until you get to the third float session. Now this session is gonna be important for some of the neuroimaging data that's gonna be presented later on because if you remember in Justin's talk he said that people were scanned before the first session and after the third session, okay? So we're interested in how floating may enhance interception. We have all these ways to measure it. What about cardiac body maps of the float experience? So this is the results for the first three float sessions. So what we call sort of the chair, chair, chair condition. This will be relevant in a little bit. So what this is is the locations in the body where individuals who are in the zero gravity chair felt their heartbeat sensations intensely. Okay, the scale here can go from zero to 10 at a maximum. In this panel what you see is the float condition and immediately what you kind of notice is that there seems to be a little bit more spread in where the float group is feeling heartbeat sensations with respect to the chair group. By the way, the group by session interaction here is significant for this comparison. So the take home message here is that floating may increase experiences of heartbeat sensations. Again, preliminary. For stomach sensation, this is what the data looks like. It's possible that there may be an effect, but right now there's nothing that is statistically significant. So I had you do all of these different ways of attending to your heartbeat sensations for a reason. And the reason is that we're trying to figure out the best ways to measure people's ability to feel heartbeat sensations in a float pool. So we've been using the least restrictive and least invasive approach, just letting people float. So the first three floats might be considered equivalent to a float in any center in the country, just asking people after the fact what they feel. But in an extension of this study, what we've been doing is looking at how people experience the heartbeat when they count it, okay? So for this study, we have added a fourth and a fifth session. So in the fourth session, the group that is in the pool goes pool, pool, pool, pool. And then in the fifth session, they cross over into floating in a chair, zero gravity chair for the first time. And we do vice versa for the other group. And the idea here is because of the experimental control we have with the zero gravity comparator condition, we can really look very closely at the different factors in floating that might explain some of the differences in interception experience. So this is just to show you that people go from the pool to the chair, and from the chair to the pool, you know what's called a crossover design, okay? We measured heartbeat counting. So we had to do some very different things in order to get that heartbeat signal. So we used a wireless measure of heart rate. We could continuously measure using something called a biopatch from this company. There are many others like it on the market at this point. And basically what we have people do is lie in the, here's an example in the closed pool. They have an ankle rest to keep it still. And they'll wear the biopatch here. We have a Tegaderm that will keep it dry. And people count what they feel. And then we compare their report to our observation of the number of heartbeats, okay? Now, because we know a lot about the pathways by which the brain receives heartbeat information, and I've already shown you that the skin seems to play a role, we need to also have an additional control. And this is something that I've called auditory contamination. So if you look at the ear, I don't know how many of you have had the experience of a long day of work, you lie down at night, put your head on the pillow, and you hear your heartbeat. Or you go and you put some earplugs on and you hear your heartbeat. You can even do it just putting your ears over your head, your hand over your ears. And I don't know how you put your ears over your head, but maybe another study. So what we know is that the middle ear has two different arteries supplying it blood. They're called the anterior tympanic artery and the stapedial artery. They come off of different vessels. And the only reason I'm making this point is that they are right near the inner ear bones. And the transmission of sound waves vibrates the ear bones and that's what you hear. So we need to actually control for this. If you float in a pool and you have your head under water or you have earplugs, you're gonna be able to hear that sensation, right? And that's not necessarily what we're talking about when we are hypothesizing that floating may improve interception. So we need to control for that. So in this study, what we've done to eliminate that confound, we don't allow participants to use earplugs or headphones. And we also keep their ears above the water using an inflatable pillow. And at this point, I don't have any statistical comparisons for this dataset. Suffice to say that we are finding some differences but they're not so far in the direction that we would expect. So the hypothesis if floating improves interception is that if you go as you have more exposure to float, so float, float, float in the pool that the accuracy here maybe would be higher than the accuracy of people in the chair float and we don't actually see that. Again, it's a small dataset. What we do see is that when you do the crossover, so the people who go from the chair, chair, chair, chair to the pool for the first time. So this you could think of as somebody who has some experience with lying in a chair but not with floating, not really much of a change the very first time whereas here, if you look at people who are experienced in a pool and they go pool, pool, pool, pool and then chair, there's a difference in the rate of accuracy. It's not statistically significant so we don't know much at this point and I'm gonna skip some of the other maps at this point. We see some interesting differences but we're not exactly sure what they mean. So I'll give you an example. If you look at this chair, chair, chair, chair group when they go into the float condition, the intensity seems to be a little bit less when they go in the pool versus the float group who goes float, float, float, float when they go in the chair. Some of this variation seems to drop away and there seems to be perhaps more intensity when they're in the chair. I have some thoughts about that, why that might be but it's not a statistically significant finding at this point so it's really just on the basis of pure description that I'm showing this to you. So in terms of preliminary conclusions at this point, it seems that floating is showing some signs of augmenting interception. From my perspective as a newcomer to this area Justin mentioned that I joined Liber recently and that's true. I also floated recently, maybe within the past year based on the subjective experience that I had and that other people have it seems to be a very unique environment and from the data that we have at this point it seems that continued research into the effect of floating on interception is worthwhile. I'm a psychiatrist as well and I have a deep interest in helping to bring novel treatments that can help for disorders that people suffer from and one of the ways to evaluate whether a new therapy is useful is to use a clinical trial. I think that there are reasons why the float environment may be useful in conducting a clinical trial. Certainly I've heard a lot of anecdotal reports from people who have floated and I think the clinical trial framework is really the best way to rigorously study and understand what the effects are of floating on health conditions. So to close my talk I'd really like to acknowledge all of my collaborators, particularly Justin Feinstein who's introduced me to floating as well as a graduate student and postdoc who worked very hard on helping to prepare some of this data. So Jesse Shetler and Steve Green and I'd like to thank my other collaborators, Martin Paulus and Kyle Simmons in my support and I look forward to meeting you at this conference and answering questions after the talk. So I'm gonna ask Kyle Simmons to come out next. He's gonna talk about a neuroanatomical model and of how the brain represents internal body sensations or interception and how his theoretical perspective brings to bear on the float experience. Thank you very much. Thank you.