What Really Happens When You Donate Your Body to Science and Research

Hello everyone, welcome to the new season of Curiosity Weekly. We are excited to be back in your ears to tell you all about the science and research being done around the world today. And this time, we 're not just in your ears, we 're also in your eyes. We're going to start publishing episodes on YouTube once a month with interviews and truly incredible stories that highlight the fantastic work of researchers and scientists from all over the world. And, as always, we want to hear from you. You can watch it on Discovery's YouTube channel or listen to it wherever you listen to your podcast. Leave us a comment about what kind of topics interest you or what people you want to know about and we'll make sure to listen. Okay, let's move on to the program. Much

of Western society has mixed feelings about death, which is funny because it's one of the few things we all have in common. It happens to all of us. In the northern hemisphere, we observe nature deteriorating and preparing for winter while we celebrate Halloween and the Day of the Dead, which mark the transition between life and death. But whether they are ghosts, skeletons, mummies or zombies, symbols of death or corpses inspire a certain fear in us. In this episode, we're going to dive right into that concept. First, we'll look at some recent research on how we experience fear in the brain. Next, I'll talk to Jonathan Bennion. He is a co-founder of the Institute of Human Anatomy, a private cadaver laboratory that

teaches anatomy and physiology to people using real human cadavers. I'm referring to real corpses. Later on, we will pass from death to rebirth naturally. A new study explains how a worm can regenerate its head after decapitation. Happy Halloween and welcome to Curiosity Weekly. I am your host, Dr. Samantha Yamin. Let's begin. As we've said, Halloween is just around the corner and I can't think of any other holiday that celebrates a specific circuit in our brain. I'm talking, of course, about fear. Ghosts, zombies, werewolves. Halloween is dedicated to things that scare us, and in fact, there is new research that sheds some light on the process by which our brain interprets the threats that trigger our body's fear response. A study led by

researchers from the University of Utah and the Salk Institute for Biological Studies discovered a missing piece in the neural circuit that tells us how to respond to fear. Before we delve deeper into that, let's talk about how fear works in the brain. There is a part of the brain called the amygdala that is buried deep within our temporal lobe. It is where we process emotions and detect threats. The amygdala detects a threat and then sends a signal to other parts of the brain, such as the hypothalamus or brainstem, to tell them to take defensive measures. Things like a startle reflex or a racing heartbeat all sound the alarm that something could

harm us and it's time to respond, whether by fighting, fleeing, or freezing. At the same time, the rest of the brain tries to provide context to ensure that it is a threat that is really worth responding to. When you watch a scary movie, for example, you may feel fear, but brain regions such as the hippocampus and prefrontal cortex tell us that it is not actually harmful and that it is not necessary to generate a full bodily response. Unless you're like me, in which case your brain doesn't do so well and you're terrified of watching scary movies. Therefore, these two systems work together to identify and respond to a threat. But a puzzle has emerged. Look, the neurons in the amygdala react to a threat in this sort of rapid burst that lasts only

milliseconds, but our defensive processes, like the freeze response, can last much longer. So what sets off the alarm bells? This new research discovered a little-studied brain region that serves as a bridge. It is called the amygdalostriatal transition zone or AST, and it is a group of brain cells located between the amygdala and the striatum, an area involved in the control of body movement, famous for its role in Parkinson's disease. The team conducted a series of experiments with mice to analyze how these cells function in this new area. First, they trained the mice to learn that when they heard a certain tone, they would receive a mild shock to their feet. They recorded the AST cells as the

mice heard the tone, and the cells continued to fire as the sound played. Then they used optogenetics. It is a technology that recently earned its developers the Nobel Prize in Physiology or Medicine. It allows scientists to turn specific neurons on or off by shining a light on them. They used it in this experiment to turn off a type of cell in this area of the brain, and the mice had an almost 50% reduction in their fear responses to sound. To take it a step further, the researchers took new mice that had never learned that association between the sound and the fear of the shock. Here, they again used optogenetics to illuminate the AST cells, and the mice were paralyzed.

Furthermore, they avoided the area where the light was on. This means that the activity of those cells alone, triggered by the brightness of that light, was enough to frighten them, and their bodies responded accordingly. Through these experiments, they discovered that this group is what helps maintain a sustained defensive response over longer periods. Basically, it provides a more continuous alarm in the brain instead of that shorter alert in the amygdala. Their conclusion was that AST cells are activated by sensory signals rather than a broad environment. And although this may sound a little strange, it is a really important piece of the puzzle to understand exactly how our brain organizes the different responses to fear.

Let's think about people with chronic anxiety or post-traumatic stress, where their brains act mechanically even though there is no real threat present in their environment. Mapping how we experience fear can provide us with the key insights we need to support these types of disorders and figure out how to make the brain respond appropriately to the right stimuli. It's what's on the inside that counts, right? Normally, when we say that, we mean our kindness, our personality, and yes, everything that matters too. But right now, I mean that literally. I don't mean to be too rude, but deep down we're all just a bunch of meat sacks. Some very impressive sacks of meat

, don't get me wrong, that can write poetry, solve crossword puzzles and even fall in love. But deep down, we're all made of the same stuff, more or less. And yet, those subtle differences in how all that biology comes together are what make us unique. Our guest knows this better than anyone and is here to delve deeper than the surface into the beauty of being human. Jonathan Bennion is a practicing physician and co-founder of the Institute of Human Anatomy, where they use real human cadavers to create educational content about the human body. You might recognize him from YouTube, where he teaches us all about anatomy and what it means for our health. Welcome to the program, Jonathan.

Thank you for inviting me. I'm excited Likewise, I think we need to start with some of your history. How did you get started in this? Yes, it's a rather interesting story because, of course, I didn't think I would own and operate my own private cadaver laboratory when I began my educational journey, so to speak. So I went to college wanting to pursue medicine, and during my pre-medical education, I had to take an anatomy class. And this was a really big class. It was one of those typical face-to-face classes with between 300 and 400 students, but there was a laboratory part where we had to go

to the lab and learn anatomy from all the teaching assistants who taught the class there. And I was lucky enough to be among the top 24 in the class, because there was a program that the professor had put in place whereby, if you scored among the top 24, he would automatically hire you as a teaching assistant. And that's when my life began, I suppose you could say, to go up or down, depending on your perspective. Yes, to go up, right? Because without a doubt that put me on a different path because I was also one of those students who had always been enthusiastic about the human body. And I remember the second practice session from when I was a student. In the first practice, we made bones, and bones are great, and I love bones and the skeleton,

like everyone else, but it's different from holding a real body part, you know? I suppose bones are technically a real body part, but most people understand what I mean by hand; it's manipulating a bone as opposed to a human heart. Yes of course. And then, I remember the teaching assistant who was giving that practical at that moment looked at me and said, "Do you want to hold the heart?" And that day I forgot my gloves and I didn't even care. I said, "Yes." And they put the heart in my hand and I remember that in a split second I looked down and thought, "Oh my God, this is a human heart." And that quickly became the best thing in the world. I had just become a teaching assistant; this program was very well

organized and helped me train to be a professor. So I started teaching in these laboratories. So, throughout my university career, I basically taught in labs and trained other teaching assistants, did dissection projects and things like that , and ended up teaching at a massage school because I'm not a massage therapist, just a geeky anatomist. And a year after starting to teach at that faculty, they severed the relationship between the massage school and the university. And if you want to make the students angry, take their dead bodies because they were in a riot. So, these two students were so angry that they said, "We can't go to the cadaver lab anymore."

Yes. For about a year, students approached me because they knew about my experience; they knew I had worked at the university for a long time. And they asked me, "Can you take us to a laboratory?" "Can you take us to the lab?" And I told them, "No, I can't take you to a random lab." So one day, after about a year of this, I was sitting at home and thought, "Maybe I should start my own lab." Mhm, that's a totally normal idea, right? Completely. And that's how the whole process began. We ended up calling state departments in various ways, since most cadaver labs are in universities, and ours, being private, was a

unique case. So we had to go through the state department, get all these things, figure out any certifications we needed. Yes, I had a similar experience in my first anatomy lab. I'm trained as a neuroscientist, so we had to cover anatomy and it was mostly about the material. But I had a similar experience. I thought he was going to be apprehensive. I was very nervous about my first day in the lab working with cadavers, and the first sight was a bit overwhelming and stressful; I guess it's a little scary. But then, once you really start to see

what you've been learning on a flat page of a textbook, it becomes much more enriching to be able to see things in 3D. And I had a similar experience when my assistant gave me a human brain and I was blown away, like, "Oh, this is someone's entire personality, existence, and memories, right here," and it helped me rethink how I see things. It's not like it's not disgusting anymore. It was interesting, fascinating, and a great honor that those people donated and supported me so that I could learn, which changed my perspective on it. But I know that many of our listeners may not have had that kind of experience. Therefore, they might be curious about the corpses. If you'll allow me to ask some questions, I have many. Many of us want to know about the smell.

Does it smell? How are they stored to prevent that? Can you tell us more? Yes. Ironically, another teacher from the high school came by today, and I was giving her a guided tour and showing her some things. She had trained at another university. And he asked me, "So where is the formaldehyde? Are they using formaldehyde? Where are the tanks?" And for those who don't know what tanks are, I call them old-school corpse laboratories. There are tanks that are completely filled with fluid, usually formaldehyde, where they submerge the bodies and simply leave them there deposited inside. And then, before a class, they take them out and place them on a kind of table so they can just stay there dripping. The smell is like

Yes. It's like those laboratories. It's like those laboratories; I don't understand why they keep doing it, since the smell is too strong. It's dirtier. It's not such a clean experience, I suppose you could say. Our laboratory, as you can see from our bodies right behind me, are embalmed. And sometimes, the body donation program and the embalmers say "fixed" or "not fixed." A fixed body means that it is embalmed. An unfixed body means that it is not embalmed. All our bodies are embalmed so that we can use them for years and years. And the embalming fluid has a smell, especially when the dissection process we do here internally is performed. And that's a stronger smell.

Can you explain embalming and how it differs from other preservation methods? I only know about fixation with paraformaldehyde, which cross-links everything to keep it rigid, but I don't know what embalming technically is. Yes, I'm quite limited when it comes to embalming. I have had conversations with funeral directors from the body donor program and embalmers. One of the things that caught my attention was the idea of fixing and stopping the breakdown of proteins, which was one of the most important aspects. And there are some similarities in the way they embalm a body for normal funeral services compared to the way they do it in a laboratory, but the embalming process for a body that is going to be in a laboratory is

much more intensive. And since those bodies need to last for years, whereas a body that may only be for an open-casket funeral or that only needs to be presentable for funeral services, is a much less intensive process than they require. Therefore, there are some differences in how they actually perform embalming and fluid concentrations and things like that. When we receive a body, the body will precipitate embalming fluid for weeks after we receive it in the laboratory. It's like a fluid with a deep pink appearance. And, generally, they enter through the carotid artery. In all our bodies, you'll notice an incision right where the carotid arteries are, and that's where they inject the

embalming fluid. And then the bodies will be kind of distended because they are trying to push all that fluid through as many tissues as possible. I said I wasn't squeamish about it, but you're really testing me. But I will say that's why we need people who are different with different interests, because it's incredible that someone can do that. Obviously it is necessary for education and even for our cultural ceremonies such as funerals. So everything is great, but wow, that's really great. I want to ask you more questions about the corpses. Where do they usually come from? I usually say certified body donor programs. And we know what

the local body donor programs are and what their requirements are. Therefore, each donor program has different rules and requirements and things like that. And we have some body donor programs that we have accessed outside of the state of Utah compared to those we have within the state of Utah. And it's really interesting because they charge different prices. And the interesting thing is that the cost is that technically you can't own a body that you acquire from a certified body donor program. You are like the body administrator who takes care of the body. And as much as I enjoy these conversations and talking with the students, I feel a certain excitement about it. As I was telling someone the other day, I remember once crying in class while talking

about this very thing. It was very funny. I was standing in front of 20 or 30 students and I was talking about this body donation process and I started to cry. We can talk about that a little later, but the point is that certified body donation programs acquire bodies for scientific and educational purposes. As someone who has been in close and personal contact with many bodies, to what extent is our internal anatomy similar from one person to another? Are there many things that tend to vary greatly? Yes, I like to tell students that we are equal, but we are not. That is to say, when you open the thoracic cavity or the abdominal cavity, you expect to find the heart located in a very specific place. You expect to find the diaphragm. You expect to find the

lungs. You expect to find your abdominal organs where they're supposed to be. And in that sense, you almost always find things in their right place. You can find abnormalities in people who may have been born without a kidney or who may have that inversion of certain organs and things of that nature. But the biggest variation I see today in thoracic or abdominal anatomy is usually the amount of visceral fat. That's one of the most important things where you'll see a difference, but you'll see things where you didn't expect them. From time to time you'll get a surprise. For example, we have a body here that had its right lung removed and expected to find three lobes, as is usually taught in an

anatomy class, and it only had two lobes. So sometimes you'll see variations like that. And as I said, you can see variations in certain organs, but those are rarer occasions. The biggest variation is the amount of visceral fat and, obviously, size. A smaller person will have a smaller heart. Shaquille O'Neal, or someone the size of Shaquille O'Neal, is going to have a huge heart, right? Comparatively. What looks so different in real life, in a body, compared to a textbook? You know, there are certain things in textbooks that do a really good job.

I generally say that the superficial skeletal muscles, the large superficial skeletal muscles, are really good in textbooks and things like that. The general basic structure of the organs in the textbooks is really good. I think the difference between textbooks and the lab is the topography. Things that are overlapping one another. As I just made a video about the gallbladder. And when you open up the gallbladder and liver together and see all the ducts that carry bile, they're all perfectly drawn, but you don't always necessarily see, well, we had to remove this and this just to get to this. And that can sometimes mislead students. Really good teachers can help deal with that if they are really good at explaining

topography to students. There's a way of saying, "Hey, what you're seeing is this, but to get there we had to go here, here, and here." That's why I think many textbooks do a good job on basic form and structural design, but topography is a big gap you're left with when you go to a cadaver lab. That's filled by going to a cadaver laboratory. Yes, the 3D structure, the layers there, how everything connects, is very difficult. I have some plastic models, but it's not the same seeing all those details. Is there anything you find really cool about human anatomy that people don't know? You know, but we run into that situation again where I think everything is fine with human anatomy

. I think that, as I've learned more, perhaps this will answer your question. When you first acquire a basic understanding of science, it challenges you in many different ways. As for the challenges, at least for me, it challenged ways of thinking, from religious to social issues, and then how science can merge with many other different topics, such as how we think in society and how people think religiously and things like that. And when I started this process, I thought I was going to get a lot of answers, and I did. I got a lot of answers, but I was surprised by the number of questions it generated for me. And you can relate to this, but the simple fact that a neuron can send an action potential is when people really

understand what an action potential is and how it works; I think many of them will still say it's crazy. Yes, I can see these ion channels and I can see these electrolytes exchanging with each other and all that. But I think maybe I'm not answering your question very well, but I think it's one of those things that has made me ask more questions and more humility, like: "Oh my God, how did this come about?" Of course. Science always generates more questions than answers. Everyone finds out I'm a scientist and says, "Tell me some interesting facts." And I tell them, "I could tell you a million questions I have about the world and then give you some answers, but that's why we're called Curiosity Weekly, because the more you learn

about how complicated it is, the more curious you get and you think, 'Does that really work?'" "Do all these trillions of cells in our bodies come together in the right way more or less every time? It's quite a strange biological dance we have. Yes. And then we go back to the idea that those trillions of cells started out as one. A complete zygote. It's like, what? You're talking about my poetry. This is what never ceases to amaze me, the process of development and the way it all ends up coming together. Anyway, we could go on and on. I've met some people whose lives were saved by

organ donors, and with such a shortage everywhere, it's something I think about a lot, so I wanted to make sure I could ask you about it here. Why are cadaveric donations so important not only for organ donation in hospitals but also for medical education and science? And is there anything you think people should know about being a donor? Yes, that's a great question too because, in my opinion, it puts us in two categories because it goes back to the driving license thing. When you tick that box, it's for, you know, Donating your organ for the purpose of

saving lives. Someone is going to receive one of your organs, and that's incredibly important to people. And obviously, the people who have received those donated organs have been given another chance at life and have had their lives extended, and I'm sure I can't even imagine what it would feel like to receive an organ from someone who did that. And that's one side of the category. And the other side of the category is donating your body to science and education. Because if you donate your body to science and education, at least from the body donation programs we have, those body donors aren't technically allowed to donate their organs to save lives, because there's a separation. When they receive the body in the

body donation programs we work with, they want to get the body back as soon as possible so they can begin the preservation process. But this is where we get to that situation where I broke down a little emotionally because our bodies here not only educate students, but we've also had companies come to test medical devices that they're trying to bring to market and that they're trying to use to help to people in life-saving situations or to prolong life and things of that nature. So, when those companies came and tried to test those medical devices, it was another eye-opening experience for me that body donation has another level for science and education. Because I was telling the story of when my mother developed blood clots and had

abdominal and pelvic surgery, and she developed blood clots that traveled to her lungs, which caused a pulmonary embolism, and that can be fatal. I'm going to say this right now, my mother is okay. Okay, I was going to ask. It was definitely a terrifying situation, and she got to the hospital and they diagnosed her very quickly. They immediately prescribed blood thinners, but one of the things they did was put a filter in her inferior vena cava. They come in through the jugular vein, go down, reach the superior vena cava, go through the right atrium, go directly down to the inferior vena cava, and open this filter. I always tell my students that It's

like a macaroni and cheese strainer, like a noodle strainer. It would catch any blood clots that came up from her lower extremities so they couldn't reach her lungs, but the blood could still pass through freely. So the anticoagulants had time to dissolve the clots she had in her lungs and even her lower extremities, but they prevented them from reaching her lungs, which is where they would first lodge or get stuck, which can cause death in certain people who suffer pulmonary embolisms. And when I was explaining that story, it was like everything just came crashing down at once. The gratitude for the people who donate their bodies to science, my mom was fine and all that, and then suddenly I. Yes. In front of 20 or 30 students. And that was one of those

great experimental experiences. And I always tell the students, especially the nervous ones, that as much fun as the lab is and as much as I like it when people laugh, because I personally feel that having positive emotions during the experience Learning helps you remember things better. And I tell the students that, ironically, this place is much more about life than death. Because these people-you always hear the phrase that the dead teach the living- but every student who comes here, whatever profession they're pursuing, is going to learn anatomy and physiology at a whole new level that they couldn't have achieved with just a textbook. And then they're going to go out there, not only helping themselves to live, hopefully, a better,

happier, and healthier life, but also helping all the people they're going to interact with, especially if they're in the medical field or fitness or whatever it is they're doing. And that's one of the things I think people might miss about the cadaver lab. It's all basically about paying it forward, and that's what they wanted to do. I imagine the body donors thought, "I would love to touch as many people as I could, sorry, with my anatomical donation." Absolutely. That's very well said, and it's a great place. To wrap things up. Thank you so much for joining us, Jonathan. That was very interesting.

Yes, of course. Jonathan Bennion is an associate physician and co-founder of the Human Anatomy Institute. You can find him as the host of his YouTube channel, where you can learn a lot about how our bodies work. You know, the popular movie trope where a supernatural person has a limb severed and then, in a usually grotesque moment of body horror, it grows back. It's an effective idea-unrealistic enough to make audiences squirm, but also realistic enough to make them cringe. Now, there are more than a few animal species that are capable of regenerating their limbs in this way. There are the axolotl, starfish, salamanders, and crabs, but perhaps none do it more fascinatingly than the planarian. This is a flatworm that can not only regenerate its head,

but recent research shows that it ages backward while doing so. Planarians are small freshwater invertebrates that can regenerate very easily. In the late 19th century, scientists proved that a fragment, just 1/279th the size of the worm, could grow into a new animal. That's a very small piece. And since then, we've learned that this is because 20 to 30 percent of their bodies are made up of stem cells. This research uncovered new information about what 's happening. Technically, the worm is getting younger during this regeneration process. Under normal circumstances, planarians age, at least those that reproduce by mating and laying eggs. In a 2025 study, researchers at the University of Michigan found that, in the 18 months

after hatching, the worms were less fertile. They moved less, and their cells were under more stress. These are signs of aging. Their heads also shrank, and they lost neurons and muscle. Some worms grew extra eyes, and others developed eye pigment spots in the wrong places. But when the heads of the older worms were cut off, the heads that grew back had eyes. normal. In addition, the proportion of eggs that hatched increased from around 6%, which is what is normally seen in old planarians, to 58%, almost matching that of young worms. The regenerated worms moved more and recovered their lost neurons. To test whether this aging reversal was localized or more widespread, the team

cut off the heads of the old worms, allowed them to regrow for 20 days, and then examined their tails, where the tissue had never been damaged. These tails showed genetic activity more similar to that of young worms than to that of old ones, suggesting that the process affected the entire body, not just the head. They also found that, although planarians age very differently from mammals, their aging patterns are more similar to those of humans than to those of mice or rats. This tells us that these tiny creatures may hold some secrets that are relevant to keeping us healthier for longer. The researchers hope that discovering how they rebuild their bodies may one day help us understand how to repair and rejuvenate our own.

It seems pretty unlikely that we can, you know, turn into Deadpool and grow a limb back anytime soon, but hey, who knows what might happen? I've been wrong before. Curiosity Weekly is produced for Discovery by the Spoke Studios team. Our senior producer is Chiara Noni. Our audio engineer is Nick Kirshenbaum. Our writer and fact-checker is Lauren Colella. And our executive producer for Spoke Studios is Cassie Burton. Thanks for listening.