 Thanks, Ashkan, and thanks, Colleen. So it's great to be back this year. For those of you who don't know me, my name is Saib Khalsa. I'm a psychiatrist and a neuroscientist at the Laureate Institute for Brain Research and the University of Tulsa in Tulsa, Oklahoma. And today I'm going to talk about floating and interception. So what is interception? I talked about it a little bit last year, but for those of you who don't remember that or who are new to this, interception is really how the brain senses the inner body. So one way, kind of easy way to think of it is sort of like an inner selfie, right? Kind of a picture of your body in the moment. But what's different about interception, unlike a selfie, is that you have this dynamic crosstalk happening between the body and the brain. And this crosstalk is different from other forms of sensation that we think of with the body. So for example, here's another term called extraception, sort of how the brain perceives the outer state of the body. Here's a more typical selfie. You may or may not have seen this. About four years ago, a photographer named David Slater left some camera equipment in Indonesia, and this is a photo that a crested macaque took of itself when it was looking at itself its reflection in the mirror, right? So it's kind of an easy way to think about extraception, visual input, auditory input. And this is different from something called proprioception, which you're also very familiar with. And here's a really good depiction of why, right? It's how your brain senses your body in space, and each of these have important characteristics. But for this talk, I'm really going to focus on interoception. So last year, I provided some preliminary results in terms of a natural history of interoception research. So my graduate student, Rachel Lapitas, and I, we surveyed the entire literature going back to 1905 when this term was actually originally coined by a Nobel laureate, Charles Sherrington. And here's what we found. So we found that since the term was coined, there was this lull for about 50 years, and there was a spike in the 50s and 60s in the number of articles published on this concept, a slow increase, and then in the last 10 years or so, it seemed like there was a rise. So for those of you who were here last year, you may remember this. We updated this, and to reflect publications in the last two years, and here's what we found. So it seems that interest in this area from the scientific community is increasing. Now one thing to appreciate is that interoception is multifaceted. So there are a lot of aspects or components to it. This is how we've chosen to break it down so you can attend to the sensation of your inner body. You can detect stimuli that occur inside your body. You need to discriminate them from other sensations. You need to encode sort of how intense is it, maybe how salient is it, how accurate are people that are actually perceiving these changes. We found that some people are rather less accurate. And then this level of self-report, so how do I experience it as a human being above and beyond a sort of quantitative measure? Another aspect to remember is that interoception has multiple channels. So in my lab, one of the main things we study is the heart-brain connection. But when you think about other channels of interoception, respiratory sensations would be one, bladder sensations would be another, genital urinary sensations, there's actually a whole host of these. And in fact, there are entire fields within medicine that are devoted to understanding and treating disorders in which different channels of interoception go awry. So with respect to cardiac interoception, last year I presented this figure describing a number of different tasks that are available to study interoception related to the heart. I'm not going to go through these in detail other than saying the two that we've tended to focus on are ones that are minimalistic. So last year Kyle Simmons talked about this visceral interoceptive attention task where you simply pay attention to your heartbeat. I'll show you some data related to that. And I talked about an approach where we used pharmacological infusions of a medication called isopraterinol, which is a very complicated word. But if you have ever felt you're adrenaline racing, that's kind of what the feeling of the drug is similar to. And one thing that I'd like to point out that's different between these two tasks is that you can see that in the interoceptive attention condition, the intensity of the body is not really changing, at least when you simply attend to your heartbeat sitting at rest as you are here in this conference room, in this theater. Whereas with isopraterinol, we're able to really enhance or increase the intensity with which the heartbeat happens, so the rate and the strength of the heartbeat. And we've shown that you can actually increase the rate at which people feel their heartbeats. So if you think about maybe a time when you were anxious or you were excited, say riding a roller coaster or whether you were exercising, I think you can all relate to that feeling and that sense of your heart racing. One of the things that I'll argue today is that floating may provide another opportunity to study how interoception is enhanced, and I'll give you a little bit of data in just a second. So the first hypothesis that we have is that really floating enhances interoceptive sensation. So if you think about your brain, so here, you've probably seen this slide before. So if you think about when people are floating, when we think about what type of information is coming into the nervous system, the central nervous system, vision seems to be attenuated, auditory information, tactile sensation, if you're not moving, you don't have as much proprioceptive input, and if you're not speaking, your speech centers are potentially relatively silent. So what does that leave? Well, it leaves aspects of your frontal lobe, and it leaves other aspects of sensory experience interoception. And the basic hypothesis that I have is that interoception is increased during floating. So I'm going to talk a little bit about the first float fMRI study. I'll present some data that you haven't seen before. I know that Justin and Pon Lin talked about the design of this study, so I'll go through this relatively quickly. But basically, we randomized healthy individuals to either floating in the pool or floating in a chair, and the chair was a comparator condition. All floats were 90 minutes, and people were scanned before and after, and we assessed what kind of sensory experiences they had, and we did a number of tasks. So Justin and Pon talked about resting state networks in the brain. Today I'm going to talk about the interoceptive tasks. Now I'll get to that in a second. I want to go through a little bit of the demographics. So 20 healthy individuals, equivalent in age, in education, and in gender, and these were healthy individuals. So we thoroughly screened them to ensure that. So these were people who did not have a history of a psychiatric condition. We verified that with a diagnostic psychiatric interview. We tested them to make sure that there was no evidence of drugs of abuse in their system, and we reviewed their medications to ensure that there were no prescription medications they were taking that could alter the cerebral responses or potentially alter their experience of the float. Importantly, this study was also approved by the Western Institutional Review Board after ethical review. So to assess whether there was interoceptive sensory enhancement with the float, we asked people after each float, during the float, how intensely did you feel various interoceptive sensations? So we asked them about the breath, we asked them about the heartbeat, and we asked them about stomach and digestive sensations. And they could rate it from zero, meaning no, I didn't feel it at all, to 100 where I felt it extremely. So when we looked at what kind of experiences people in the chair condition had across all the three floats they did, they felt it mildly and pretty equivalently across. When we looked at the float pool condition, we found these effects. So people who floated in the pool reported a significant increase in breathing sensations, heartbeat sensations, but interestingly not stomach or digestive sensations. Now I realize this is probably not news to any of you who run float centers or have floated a lot, but here is some quantitative evidence to support this experience that many people have had. So here's some evidence that maybe floating enhances interoceptive sensation. There are other ways to look at this, so you can look at the bodily representation, sort of how people perceive their sensations in the float pool. We'll talk about the heartbeat next, and that's using these cardiac body maps. I showed a little bit of this last year, but this is the updated finding. So basically what we asked people to do is, before they floated, we asked them to trace on a mannequin where in their body they noticed their heartbeat sensation. And then we asked them after they floated to do the same, and we did that with each float, with the chair condition, and also with the pool condition. And so what did we find? Well, before they floated in the chair, this is where people tended to report feeling their heartbeat sensation. So in terms of all of the trials that we collected, there was a higher density up to 32 percent of the ratings in a region that is consistent with the anatomical location of the heart. So what about in the chair condition? We found some differences. So there was still a sensation of the heartbeat in the chest, but there was also seemed to be a spread to other regions, like the abdomen and the neck, maybe even the back. So this is kind of interesting. When we looked at the pool condition, this is what we observed. So again, similar location. And here's what we found in the pool. So a spread now, again to the abdomen, again to the neck, but also the face, the shoulders, the arms, and a larger region in the back. And if you look at this all together to kind of make a visual comparison, you can see it a little bit easier. So similar rates of overlap in the pre-float conditions in both. In the post-float conditions, you can see that actually, even in the chair, there was greater overlap in the post-float versus the pre-float. And in the pool condition, there's an even higher overlap. So this was kind of interesting. So we see some similar effects with the pool as with the chair, but we also see some differences. And it caused me to think a little bit about how is it that we feel our heartbeat? What are the forces at play when you're lying down? Because people were lying supine in the chair, just like they were in the pool. And if you think about the heartbeat and how the dynamics of blood flows throughout the heart, right, your heart is part of a circulatory system. You have an arterial side, you have a venous side, and it's constantly circulating. And Colleen talked very nicely about some of the effects with systolic and diastolic blood pressure. There are actually some changes that occur with blood pressure when you go from lying down to sitting or standing, or from standing to lying down. So if you're lying down and you stand up, gravity causes blood to accumulate in your venous system away from the heart. And what that does is that it decreases blood flow to the heart, which decreases a variable called cardiac output, so the amount of blood that your heart can pump into the arterial system, which causes your arterial blood pressure to fall. Now if your arterial blood pressure dropped to zero every time you stood up, you would faint. And so your body has evolved some complex autonomic cardiovascular reflexes to adjust and prevent that from happening. So if you are healthy, your autonomic nervous system engages what's called the baroreceptor response. And so when you stand up, your vessels contract, and you can maintain blood flow throughout the organism. So what happens when you lie down? Well, when you lie down, blood volume shifts towards the heart. So rather than blood flowing away from the heart, it shifts towards the heart, which increases your cardiac output, which increases the amount of blood that the heart pumps throughout the body with each beat. So if you look at these maps and you look at the circulatory system, right, you have a thoracic aorta, an abdominal aorta. You've got carotid arteries. You've got brachial arteries. You've got arteries throughout your entire body. And clearly lying down in a comfortable chair causes some of these dynamic changes. But what's also clear is that if you're lying in a pool, those changes seem to be different, seem to be larger. People seem to feel perhaps more of a spread in terms of the sensations themselves. So I think that's very interesting. That, I think, provides some additional evidence that floating may indeed increase interception during the acute float process. What about brain activity? So I'll introduce you to a task that we used called the visceral interceptive attention task. So basically what we ask people to do is simply pay attention to the feeling of inner body sensations after they floated. This task is based on something called the neural spotlight effect, wherein when you attend to a particular process, neurons in the brain that are involved in that process increase activity. So when you attend to the heart or to the stomach, neurons in those regions should increase. Whereas when you attend to something that's not internally relevant or rather it's extraceptively relevant, like the word target, you don't have activity in those areas of the brain. So we ask people to do this task after they floated in the pool and after they floated in the chair. And this is what we found. So we contrasted, first of all, the interceptive attention versus the extraceptive here. I'm only going to show you data for the heart versus target. And what we found is that a region of the brain on both sides, called the insula, shown here. This is actually the posterior insula. Here's the entire extent of it. Showed a significant increase in activation. So simply attending to the feeling of the heartbeat after the float seemed to show that there was increased activation in a region of the brain that seems to represent inner body sensations. What was interesting is that the more that subjects experienced their heartbeat during the float, the greater the amount of posterior insula activation during this attention. But it was only in the pool condition, okay? So this is a plot showing that. Here's another view of the insula right here. Here's the posterior cluster. And what you can see is these blue dots are the pool group. And these gray triangles are the chair group. And you can see that heartbeat intensity in the third float was increased for a number of them. It seemed to increase more for this group. And there was only in the pool group a significant relationship between activity in this region of the insula and the subjective experience that people had. So this got us pretty excited. And we're in the process of preparing this for publication. But what really got us excited was when we thought about other studies that we had done that allowed us to also increase inter-receptive sensations. I mentioned the adrenaline study. Well, my lab with a very talented postdoc as the first author, we just published a paper where we showed that when you increase the heartbeat and increase people's sensation of the heartbeat with a drug, you get activation in a very similar region of the insula, the posterior insula, only on the right in this case. So these data suggest that a common region of the insula may be mapping the sensation of increased cardiovascular change but across two very different conditions. So we've learned something I think about floating, but we've also learned something about inter-reception. So to summarize this first study, it seems that floating appears to enhance inter-receptive sensation. The evidence for this seems to be through these increased reports of cardiac and respiratory sensation, through the increased localization of cardiac sensations in the body, and also the preferential engagement of a body-sensitive brain region, the insular cortex. So I'm gonna move to talk about a different study. This is now a clinical study that we're doing at the Laureate Institute for Brain Research with patients with anorexia nervosa. So last year, some of you who are here, you probably heard Emily Noren's very compelling account of her personal battle with an eating disorder and the role that floating played in her recovery. So we have an eating disorders unit in our institute, actually two floors above us. I have a very active program in studying this condition. And we wanted to begin to investigate how floating might play a role in this disorder. But let me first make the case for why. So first of all, anorexia nervosa is a rare but very deadly psychiatric disorder. So it only affects about 1% of the population, 10 to one female to male. But it has one of the highest mortality rates, if not the highest mortality rate in psychiatric disorders, 20% lifetime, which has been estimated to be two to three times greater than bipolar disorder or schizophrenia. What's worse is that current treatments really only have moderate efficacy. So while they're able to oftentimes reduce the severity of symptoms, there are very high relapse rates. So up to 50% at one year. Also medications appear to play a relatively limited role in treatment. And that's primarily because across the studies that have been done, across the clinical trials and across clinical experience, medications don't seem to work too well at reducing the symptoms of anorexia nervosa. What are the symptoms? So if you look in the diagnostic and statistical manual, or you ask a clinician who treats eating disorders, they'll say that anorexia nervosa is characterized by severe food restriction causing pronounced weight loss. So a weight that's much, much lower than normal. However, despite the fact that people's weight is very low, they have an intense fear of gaining weight. And these are individuals who have a very disciplined ability to ignore hunger signals, to ignore food resulting in emaciation of the body. In addition, they have a disturbed body image perception. So the classic phenomenon you might see represented is that these are individuals, when they look in the mirror, they see somebody who is physically much larger than they actually are. Physically much larger, much fatter than the way they perceive themselves, or the way that others perceive them. In addition, there's a high degree of anxiety in terms of anxiety disorders. So people are often diagnosed with an anxiety disorder before they ever develop anorexia nervosa or they develop it afterwards. They have high amounts of obsessionality. Obsessive compulsive disorder is highly comorbid. And they're often seen as perfectionistic as a trait, lifetime trait. What's more, and this is relatively less emphasized in the current literature, although I think there's been some increasing recognition of this, is that these patients oftentimes have difficulty recognizing emotional states, sort of what emotion am I feeling right now? How am I feeling? And also inner body sensations. They often have a intense preoccupation with sensations from their stomach, even when it's not clear that there's any particular disordered process going on. These patients often complain of constipation. They'll eat small amounts of food and feel extremely full. So why floating? Impaired body image perception of the body from the outside, increased anxiety, and altered bodily sensation. All things that it appears that floating acts on. So we wanted to investigate this further. The basic hypothesis, it's very limited, so I won't present a lot of data today. Certainly not any immediately conclusive results that we can submit for publication, but the first thing we have to ask ourselves is, is floating safe? And the basic hypothesis that we have is that floating is safe for individuals with anorexia nervosa. A number of you who run centers may have individuals come in who self disclose this as a diagnosis. But there are a lot of possibilities where individuals could potentially run into trouble when they float. What if they get really anxious when they're in the float pool? What if their blood pressure changes? What if they stand up and all the venous return goes away from the heart and they feel dizzy and lightheaded and faint? So this is really a safety study where we're seeking to establish whether the act of participating in floating is safe. In doing so, what we wanted to do was find individuals who are relatively recovered from their condition. So what we did was we consented participants. They had a face-to-face psychiatric evaluation. They had a detailed behavioral assessment. And first, we asked them to undergo floating, but we asked them to float in a chair. And what we did was we did some very detailed measurements of their blood pressure. We measured what's called orthostatic vital signs. Patients who come into the eating disorders unit who are often very underweight, very dehydrated, it's routine for them to feel dizzy when they stand up. It's not uncommon for them to faint or fall. And so they're oftentimes very, very closely observed. Well, we didn't want that to happen. So first we measured orthostatic vital signs when people were in the chair. So they were clothed. We had a nurse, my lab manager, who's right next to them in the event that they felt that way. And after we could ensure that they didn't have any orthostatic hypotension, we asked them to then come back and float in the open pool. And we followed that by floating in the domed pool or the closed pool. And we had a very specific reason for doing this. So a number of patients who have elevated anxiety often report claustrophobia being in enclosed spaces. And we felt like this would provide a nice graded way for them to get used to the idea of floating. And finally, we had them float again. So some of the effects that people have hypothesized about floating appear to have a chronological relationship. So the more you float, the more the benefit you get. So we wanted to be able to examine this across multiple floats, but three floats. All of the floats were 90 minutes. And we assessed several autonomic parameters. So Colleen did a great job of talking about the blood pressure, the heart rate, the EEG changes. We measured a lot of these parameters during the first and second float. We wanted to give people an experience of floating which is more consistent with what happens in the community in many of your float centers. So we had a float where there were no sensors. And then we repeated the sensor measurement for the fourth and final float. So at this point, where are we in this study? We have recruited six participants thus far, all relatively young, about a little more than high school education, all female. Importantly, these are people who have a normal body mass index. So you can see the range right here. Normal is 18.5 and 24.9 is the high end of normal. And the point here is that again, we wanted to start with people who are actually clinically doing fairly well. People for whom we weren't worried of them developing orthostatic hypotension because they weren't acutely underweight. Not surprisingly, their eating disorder symptoms were on the low end of the spectrum when we used the eating disorder examination questionnaire. If you look at a more clinical population, more acute, that number would be much higher. So they were all weight restored and clinically stable, but despite that, we found some residual evidence of disturbed body image and heightened anxiety. And this is a very common phenomenon in the field of anorexia nervosa research. Some people have called this the illness scar, sort of symptoms that persist beyond acute treatment. And we found evidence of that. So I'll talk about preliminary results. Now this is an ongoing clinical trial. So it's a safety study. I'm pleased to report that first and foremost, we haven't seen any evidence of orthostatic hypotension or dizziness. So there's no adverse events. And I'll show you a little bit of data in the last few minutes about some of the findings in the first couple floats. So again, this is a small sample, but I thought you'd be interested to see this. So the first thing that we noticed is that during floating, this is the pool, sorry, this is the chair, and then here's the pool. This is only the first float. We see some significant decreases in diastolic blood pressure, even evident within the first float. It's unclear whether this will be a trend. Certainly others, including Tom Fine's pioneering research has shown that reductions in systolic and diastolic blood pressure occur. We see decreased diastolic at this point. When we look at the trajectory of blood pressure during the float, so what we see within individuals even, not too many changes. So this is a single individual before, sorry, a single individual during the chair float, and then here's their blood pressure value during the pool float. So this person had a decrease. This person really stayed flat. What's clear is in the diastolic condition, everybody goes down a little bit. When you look at the trajectory of blood pressure during the float, what you can see is that there seem to be some increases at the midpoint in the chair, and you see this early decrease followed again by this midpoint increase. I'm not sure what that is, but that's kind of what we're observing. Whereas with diastolic blood pressure, the pattern is different. So we see across the board sustained decreases during the very first float. How about affect? So we assess people's experience of emotion during the float using a scale called the Ponus X. So Justin has mentioned this to you before, talked about some of the different sub-scales. There are different sub-scales in this and what we did, so there's one called negative affect, positive affect, joviality, serenity and fatigue. I think Justin has presented on this. Let me just tell you about some of the terms and I'll show you what the changes actually were. So negative affect is basically how afraid were you, nervous, irritable, guilty, ashamed. And what you can see, these are change scores, so the maximum possible change is 100. You can see that floating in a chair is associated with some decreased negative affect, and it decreases a little bit in the first float. But what about positive affect? Well, positive affect terms are rating things like how active do you feel, how alert, attentive, inspired. And what we see is positive affect seems to go up in this patient population. We looked at joviality, which is how happy, joyful or energetic do you feel. It also seems to go up preferentially in the pool. Serenity is how calm, relaxed or at ease do you feel. Interestingly, the float in the chair seemed to be somewhat serenity increasing in this population, but the pool was even preferentially above that. And then in terms of fatigue, how tired, sluggish or drowsy do you feel actually went substantially down in the pool. How about some inter-receptive changes? So we asked people again how intensely did you feel your heartbeat, your stomach, and your breathing sensations? And what we found interestingly, so this was predicted, so breathing sensations increased in these patients, which is consistent with the data I showed you before. Heartbeat sensations also increased in the first float in the pool, but stomach sensations actually decreased. And what was interesting about this was that I thought back to Emily's presentation and how she talked about the fact that floating was an environment that seemed to allow her to tolerate the discomfort of eating. She would float after a meal. It seemed to decrease the impact that those meal-related sensations had on her feelings. Whether or not this will hold, I'm not sure, but preliminarily, it seems somewhat interesting. We talked to people afterwards and we asked them what they felt. So this is sort of straight from the participant's report. After the first pool float, we had one participant who said it went really well. I felt more relaxed and refreshed. This goes along with the ratings. After the third float, she said, I guess I didn't know I could have less anxiety or better body image. That's kind of interesting. It's anecdotal, but again, this is what she said. We had a second participant who came in and said, after the chair float, I'm feeling anxious, but that's pretty much how I usually feel, anticipating what I need to do for the rest of the day, which is not an uncommon thing to hear, somebody who's highly anxious. But after the first pool float, she said I'm feeling more relaxed than I was when I came in. Definitely, and excited about the day and upcoming things. After the third float, she said this was definitely the best one. I feel a lot more relaxed, more steady, not as emotional and a little more rational, which is unusual, because normally I don't feel that way. I feel illogical. And when we asked her if she learned anything about herself during the experience, she said I keep being surprised and startled by how unreliable my anticipation is of things. I really need to take more time to just sort of be quiet because I really do and I think a lot of people avoid that. So I thought that was really interesting. So to wrap up, floating appears so far to be safe for individuals with a history of anorexia nervosa. We don't know about individuals who are acutely in the illness state, who are on the inpatient unit, but we don't see evidence so far of orthostatic blood pressure changes. We see some increases in positive affect and decreases in negative affect. We don't appear to see a worsening of body image disturbance, but I think that further study is warranted. I think that affected individuals, particularly in the more acute state, is warranted to determine whether it's safe for them and maybe at some point in the future to evaluate the potential efficacy as a clinical intervention. So I'd like to thank all of the people in my lab. I'd especially like to thank Dr. Scott Mosman, who's the director of the eating disorders program, Justin Feinstein, my colleagues Kyle Simmons and Martin Paulus. I'd especially like to thank the float conference organizers for allowing me to come and present to you. So thank you very much. Thank you. Thank you. Thank you.