Go back

This Is Your Brain on Psychedelics

from StarTalk with Neil deGrasse Tyson

74m 17s

This Is Your Brain on Psychedelics

The episode explores how psychedelics restore neuroplasticity by reopening critical periods—windows of heightened brain plasticity seen in early life. This process, observed across psychedelics like psilocybin, LSD, and ibogaine, allows the brain to rewire itself, particularly in treating conditions like PTSD and stroke recovery. The duration of the effect correlates with the trip length, with longer trips like ibogaine extending benefits for weeks or months. Crucially, these effects are context-dependent: they work best in safe, supportive therapeutic environments, not isolated or chaotic ones. The research suggests psychedelics may help reframe traumatic memories by enabling emotional re-evaluation and adaptive learning. While the idea of "teaching an old dog new tricks" is highlighted, animal studies—especially with octopuses—show that complex behaviors can emerge without human-specific brain structures, offering evolutionary insights into brain function. The episode also emphasizes the importance of context and emotional vulnerability, noting that psychedelics foster a "noetic" experience—of deep, real-world awareness—that supports transformation in mental health, relationships, and learning. Though promising, psychedelics are not a panacea; their effectiveness is limited in neurodegenerative diseases like Alzheimer’s, where neuron loss cannot be reversed. Overall, the discussion positions psychedelics as a powerful tool not just for therapy, but for reactivating fundamental brain processes that enable lifelong learning, resilience, and human connection.

Transcription

10419 Words, 57924 Characters

English
Dang! Octopus is on psychedelics. Can't top that. We'll try. I guess you can. Two Octopus is on psychedelics. Coming up next wave psychedelics on Start Talk. Welcome to Start Talk. Your place in the universe where science and pop culture collide. Start talk begins right now. This is Start Talk's special edition. Which means I got to my right right here. Gary O'Reilly. Hi Gary. Hi Neil. All right. Yeah. And who else we got here? Could you be Gary's younger brother? It's true he is. Chuck Knife. That's right. All right. So we on special edition, specialised in the human condition. Yeah. So I think you put something together today, you and your producers. Yeah. Lane over in LA. In our LA office. And I think this one puts us over the top. Really? Yeah. I'm at the top of what? I don't know. We'll find out. Anyway, it's about time I think we had this show. That's what I'm saying. The special edition, as you've been saying, is the human condition. But what happens if we give it a nudge? What if I told you we can take back our brains to a time when it was eager to learn the lessons that would last a lifetime? Go back to last Tuesday. If you wish. I mean spoiler chuck, there are no shamans in this episode. Oh come on man. So you don't mean evolutionarily. You mean just in our own lifetime? Yeah. Okay. You're not going to go back to our lizard brain. You're just going to go back to our childhood brain. Yes. Okay. Unless you're a lizard. That was good. That was good. All right. Neil, please bring it up. We have for the first time on Start Talk, Goo Dolan. Goo, welcome to Start Talk. Thank you very much. Nice to be here. You are a professor at UC Berkeley in the Department of Psychology. But you also attached to the departments of psychedelics. All right. Now we'll talk and nurse. Yes. Yeah. What Berkeley has a department of psychedelics. Is that true? No, no, no. I mean, I'm a neuroscience and psychology are the two departments I'm associated with. And then we have a psychedelic center. And I'm part of that as well. That was I was a part of the psychedelic center. And co-author of a book from 10 years ago, the essential pathways and circuits of autism. Oh, that's something that's amazing. Had her on for that. Yeah. Yeah. Why do we have you on for? Yeah. That's a great con. That's a great con. We'll get you back. We're not having that for that for autism for sure. The leader in the field of psychedelics, I have here unlocking our neuroplasticity. Yeah. One of my favorite words of the last decade or so. That went along with with terraforming. The came out of astrophysics words that just no other word was there. Right. And we have it here. Neuroplasticity. And for the treatment of PTSD, something that has been long sought after, of course. So did you come to this field as just an ordinary psychologist or did you have pure neuroscience, psychedelic chops or at least curiosities before you became an academic? Yeah. I've been studying the brain since I don't know, 1998. And I started out first studying wholesale patch clamp electrophysiology, um, doing learning and memory studies. And then I switched over to doing in vivo electrophysiology and studying critical periods, which I'll tell you about as they relate to diseases like autism. And then I finished medical school, actually. And I did an MD PhD and then I decided I didn't really want to see patients and then I wanted to keep doing research. So then I did a postdoc at Stanford and there it was also neuroscience focused on discovering the neural circuit underlying social reward learning. And then in 2014, I started my own lab. And then I finally got to work on the stuff that I really wanted to work on, including psychedelics and octopuses. What an underachiever. I love how you just threw that in as a throwaway psychedelics and octopuses. They go together perfectly. Of course, they go together. Every time I get in the ocean, I'm like, I hope I see a octopus who's tripping his tentacles off. Well, I think Ringo star beat us to it on the octopuses garden business. All right. That's right. So could you explain what the human fascination has been for millennia for things that alter our state of awareness? And I ask that very sincerely because as a astrophysicist, I highly value objective reality. And so to alter my state of mind for whatever tripping that involves, I so undervalue that compared with objective reality. And so can you help me understand people's urge to escape reality? Well, you know, I'm not sure that it was originally necessarily discovered by humans. I think that there's evidence that animals use psychoactive drugs and we sort of tried them out, testing them on ourselves, watching the animals do it first. And in fact, there's a long line of evidence to suggest that psychedelics were used in traditional cultures as medicines more than just for the fun of it. Makes sense. And we learn how to use plants and fungi from you know, animals probably mostly in the healing capacity more than the altered states of consciousness kind of capacity. However, I will say that we have some mechanistic insight into what psychedelics do to the brain. And I'll talk about it more, but we think that they reopen critical periods. And it turns out that psychedelics aren't the only way to do that. And humans have been doing those other practices for a really long time as well. So what you're saying is psychedelics worked its way into cultures with tap roots in medicine. And now we're making coming full circle looking to psychedelics once again to see how it can serve people who are in desperate need. Listen, the tribe that I did Ayahuasca with in Costa Rica, they are from Colombia, but they have been practicing this before recorded time. These same lineage of people. And they do not call it Ayahuasca. They call it the medicine. Ayahuasca is our word. And that's how they refer to it. And the ceremonies and everything that they do in the ceremonies are geared towards healing. And so that's the way they see it. All right. Interesting. So LSD was formulated as a respiratory and circulatory treatment in 1938. I'm not mistaken. So when did our perception of what psychedelics could actually do change? Well, Albert Hoffman, who was the first to synthesize LSD, is a famous for having decided it must be having some big psychotropic effect. Though he can't really pinpoint how he got that notion in his head, maybe in a dream. He just had an intuition that it was doing something more than what he could tell it was happening when he gave it to a mouse. So he estimated how much he should take based on the potency of, you know, another drug like aspirin or ibuprofen. And based on that estimate, he took approximately the equivalent of 250 hits of acid and wrote it's bicycle home. And so LSD is one of the most potent molecules that we know of. And he had, it was the first time anybody had taken this malloc, any human had taken this molecule. And he had a very, very big experience. He was accompanied by his colleague and a nurse who helped him go through that experience. And then he realized that it was a really different kind of medicine, and that it was potentially useful at the time when they first started researching it, useful as a way of trying to understand insanity. So the first name of psychedelics was psychotomatic because it mimics psychosis is what they thought at the time. Of course, now we know that the psychosis that we see in schizophrenia or other times types of drug overdose is very different than the psychedelic properties of psychedelics like LSD. I want to just revisit something you said about critical periods and I'll ask you to explain what they are but they fold nicely into your work with is it octopi or octopuses? It's octopuses because it comes from Greek nut latin so the latin is pulled off. So you were working with octopuses with MDMA and you've sort of uncovered some things here. So would you sort of expand on your research and weave into that the explanation of critical periods? When you say working with octopuses and MDMA, were you getting octopuses high? Yeah, I actually we were already working with MDMA to study critical periods in mice and I had become interested in octopuses because another friend of mine, Carrie Albertin had just published the genome of the first octopus and I thought this is great. I'm going to be able to study brain evolution using these species and a collaborator, a friend of mine, Eric said you know we have seven octopuses available. Would you be interested in doing any experiments on them? And I said sure. So he FedEx them to my lab in Baltimore and then he flew down and then we gave them MDMA and we asked what happens to their social behavior. So octopuses are crazy a social so they will kill each other normally if you put two of them in the same tank. But if you give them MDMA then their behavior completely changes. And so now I don't know why we had a problem in the first place man. I love you man. I love you. I love you too man. I want to give you like an eight arm hug right now. So the social reward critical period. Okay, I can say it but what actually does that mean? Is that one of a whole load of different critical periods that we will have in existence in our brains? Yes, so just to be clear the octopus experiment was looking at the acute insects of MDMA and we were not measuring critical periods there. I was going to say because from my own experiments with MDMA surely in the name of science. Of course. I understand it to be you know a serotonin reuptake inhibitor right? So it's just basically your body, your brain floods itself with a bunch of serotonin and then you feel so good and loving and all the stuff that that does for you. How close are their brains to hours that they would get that same response? Yeah, so first of all it binds the MDMA binds to the same transporter protein that a serotonin selective serotonin reuptake inhibitor like prozac binds to but it's the same transporter. But when an SSRI like prozac binds to it it blocks it so that rather than vacuuming up all of the excess serotonin from the synapse when MDMA binds to it it reverses the direction so now it's just extruding a bunch of serotonin into the synapse. So SSRIs work by allowing the excess serotonin to not get vacuumed up. MDMA is much more powerful because it causes actually serotonin excess to be released right? Right yeah and that's why you feel like shit the next day. Well you know some people report that they feel bad the next day but other people do not and so this sort of hangover of social good feeling that part of it we haven't really got a big handle on. We know that if you give 50 times the normal recreational dose of MDMA many days in a row to an animal you can deplete serotonin from the transporter stores but it's not clear that that is what's happening when people report that they're having a hangover and it probably has more to do with metabolism of the molecules by the liver. Here's yet another fact from lost in space five thousand facts for navigating the universe. If Jupiter were hollow you could fit a thousand earths inside of it and you know what else? Jupiter rotates so fast it makes one full revolution every 10 hours. If you like that fact you can find 4,999 more in lost in space. 5,000 facts to help navigate the universe. The latest collaboration between star talk and national geographic books. Lost in space is now available for pre-order wherever books are sold. Is everything psychedelic using the same mechanism to achieve what it needs to achieve or can achieve? Yeah so Gary this is a great question. I think that there is a common mechanism across all of the psychedelics but the proximal mechanism is probably very different across psychedelics. So what I mean by proximal mechanism is that different psychedelics bind to different receptors at the beginning so ketamine seems to be working mostly through the NMDA glutamate receptor whereas psilocybin and LSD they bind to you know almost every G protein coupled receptor we know of but the one that is responsible for the hallucinogenic properties seems to be the serotonin 2A receptor. MDA as we already talked about binds to the serotonin transporter but also to the nor epinephrine transporter and the dopamine transporter whereas iBegame is a really sort of unique psychedelic in that it seems to bind a little bit and at low affinity to lots of different things including the kappa opioid receptor, the NMDA receptor, the serotonin transporter and not at all at the serotonin 2A receptor. So despite the fact that they bind to different receptors what we have shown is that downstream of that receptor binding they all seem to do something similar in terms of restoring something that i'll explain is called meta plasticity so restoring the ability of the brain to induce plasticity and they seem to converge at the level of extracellular matrix remodeling. So those mechanisms seem to be the downstream unifying mechanism that brings them all together. What you're saying the brain needs to be needs to have a plasticity enough to have a plasticity? Yeah so let me explain why i actually don't like the word neuroplasticin or psychoplastagen. Plasticity is something that we that happens all the time like right now i am having you know this wonderful conversation with you guys it's emotionally very strong for me and get to be on this great podcast and so i'm going to remember a lot of things about this day probably the hours and days before and after this because it's a very powerful emotionally powerful moment for me. Now we feel the same about you thanks. So you know it's going to have it's going to cause plasticity in my brain so everything that you learn is going to induce some amount of plasticity but that plasticity is you know follows a bunch of rules you know it's associative it's you know depends on how what else is happening in your life most people are able to remember for example other big emotionally salient moments in their lives like the birth of a child they're wedding day the explosion of the challenger the 9/11 those are days that you know get encoded very strongly because they're emotionally same and that is all happening by plasticity. We also know that drugs of abuse like cocaine induce massive amounts of plasticity and the plasticity they induce is sort of not following the rules it sort of doesn't care whether you're hungry or not hungry you know you kind of when you start using cocaine it's like i love it here i love it there i I love it everywhere and I don't care if I'm hungry for cocaine or not, I just want it, right? And so that type of plasticity or hyper plasticity is associated with addiction. That kind of plasticity is very different than the kind of plasticity that we are observing with psychedelics. What psychedelics do instead is they seem to not do so much plasticity by themselves, although of course the trip itself, if you saw God or something, that's probably going to be a very emotionally meaningful memory in and of itself, but the therapeutic effects we think are because what happens after that big psychedelic experience is it restores the ability to induce plasticity to levels that are similar to the ability to induce plasticity when you are young, when those critical periods work. So do the effects of this re-opening of a critical period last beyond the pharmacological effect of the drug itself? Yes, yes. And so this is actually something. Is that the magic? There is the magic there. So you know, this is something really cool that we discovered when we looked at the time course of critical period reopening. When we looked at different psychedelics where the trip lasts different amounts of time, we saw that how long the critical period stays open after the acute effects of the psychedelics have worn off is proportional to how long the trip is, right? So if you've got a psychedelic like ketamine where the trip lasts only about 30 minutes to an hour, then the critical period only stays open for about 48 hours and by one week it's closed again. LSD, you know, the trip lasts about 8 to 10 hours and the critical period closes at about three weeks. MDMA and psilocybin are something in the middle, the trip lasts 3 to 6 hours and then the critical period stays open for about 2 weeks and then it's closed at 3 weeks. I began, which is the rock star of the psychedelics, the trip lasts, you know, 2 to 3 days and the critical period stays open for at least a month, although probably longer than that, we just didn't look any further out. Now, when you just for clarification, because I want to make sure I have it, and maybe somebody else is listening, when you say plasticity, what you are talking about, yes or no, is this what you're talking about? You have experiences or behaviors, occasions, whatever, and they cause your neurons to fire in a certain way that wires your brain according to the experience that you are having and then that makes an imprint on you and that can change based on different experiences and so forth. Is that what we're talking about when you say plasticity? Sorry, yeah, I should have clarified. When I say plasticity, I am talking about synaptic plasticity. It's a change in the synaptic weights that are encoded when two neurons talk to each other. The weight of those synaptic connections can change, they can change in either direction and the pattern of synaptic weights across a neuron, across distributed networks of neurons, ranges as the representation of the memory changes. So neurons that fire together, wire together, and neurons that are out of sync lose their link, that sort of thing. Lose their link, okay. And so that bidirectional synaptic plasticity is the leading theory of how memories get encoded by the brain. Well, because it's very, very sparsely encoded and it's dynamic and it is distributed across billions of neurons and trillions of synapses. And it's not encoded in philosophers have speculated about the existence of a grandmother cell. For example, you can just poke an electrode down in the brain and identify the neuron that responds to grandma. We have never found anything that looks like that. Instead, it looks like the way that the brain encodes memories is by population coding. So the changes in the patterns of activity across many, many, many, many neurons is how the memory gets encoded. So an analogy that might be useful is think of a QR code. So if a QR code represents all of the, a cell, a neuron and the black and white pixels on that QR code each represent a synapse, the memory isn't the whole block turning, you know, more black or more white, it is the pattern of black and white pixels on that QR code. And so the memory is just how the pattern changes, not some sort of gradation, graded effect, which makes it very difficult to measure from a distance. Yeah, and is that could that also be, and maybe there's a different reason, but what I'm hearing, maybe that's why memories are so unreliable, you know, in terms of the recall. Well, I mean, I think that they can be unreliable if you think of them as being constantly modified, right? So things that are very reliable memories are the ones that are essentially encoded because, because the same event triggered sort of redundant network and neurons, reinforce, either reinforce because of a reward signal or reinforce because of a fear signal or reinforce because it was so powerful at the moment, your olfactory system, your visual system, your emotional system, your social system, all of these networks encoded it redundantly. And so you have lots of different ways to access that memory sometime in the future, right? Whereas if something just happened today, and it was like, oh, home, you know, just another, you know, hard boiled egg for breakfast, you probably will only encode that in the least redundant way possible and it will kind of fall away over time. Wow. That's great. Great explanation. Our neurosciences now looking at psychedelics as the master key that will unlock the brain's plasticity. Yeah. So that's definitely the way that my lab and like a handful of other labs that have reproduced our findings are finding and I just want to back up to you to explain what a critical period is and why this is such a big deal for neuroscience. So critical periods were first discovered and or first described in 1935 by Conrad Lorenz. He used that term to describe imprinting behavior and geese and what he noticed is that those baby ghostlings sort of within 48 hours after hatching will form a lasting, really robust learned attachment to whatever is moving around in their environment. So normally that would be their mom, but if mom isn't available, it can be any other, you know, caregiver in the immediate environment, but it can also be, you know, a cookie scientist like Conrad Lorenz. But after that first 48 hours is over, then they no longer are sensitive to what's moving around in their environment and they don't learn those attachments. And so Conrad Lorenz called that a critical period. Basically every memory that we, every part of learning and memory that we think is important for enabling humans and other organisms to develop complex behaviors. We think now is regulated by a critical period because there aren't enough genes in the genome to encode every possible behavior. Instead what's encoded is the ability to flexibly learn from your environment depending on what you're growing up with, right? So it doesn't make any sense to have, you know, a genetically hardwired one single language to rule them all, if you will, instead what you're born with is the ability to learn whatever language you happen to hear in your environment when you grew up. So for me, it doesn't make any sense to be genetically hardwired with Turkish. I learned English because I was born in the United States and then also Turkish because my parents spoke it to me. So language is also governed by a critical period and what we have discovered over, you know, since 1935 is that there are dozens of critical periods. We haven't discovered all of them yet. And probably the reason that we're so terrible at curing diseases of the brain is because by the time we get around to intervening, the relevant critical period has closed. So Neuroscientists have been dreaming of awarding. way to reopen critical periods basically since 1935. And so when I was a graduate student at MIT, I remember there was another competing lab at Harvard. And they were making the claim that we just have to understand these mechanisms. And eventually we'll get a master key and we'll be able to unlock them. And I remember sort of making fun of that idea. I was like, no way anything that would do that to the brain would either cause it to structurally melt down or cause amnesia or cause some kind of seizure activity because of what we know about the mechanisms of critical periods. So it was quite surprising to me when we first discovered that psychedelics reopen critical periods and that in fact, all of them do it. And now it seems that they share the same mechanisms as other ways of reopening critical periods that we've known about for a really long time. And now a bunch of other labs have shown that they can reopen not just the critical period. We discovered but other critical periods that people have been working on for a really long time. So can I ask you this? OK, based on what you just explained to us, which sounds really cool. There's a lot of potential there of what you just said. But what came to my mind, and I'm a huge advocate for people to use psychedelics for positive purposes. But the way you say this opening a critical period, I also kind of hear maybe opening a Pandora's box because that critical period, like maybe there are some things in there that were neatly tucked away and then you open it up and now I'm totally effed because there's things in this critical period are open again to me. So what do you do for that? So is it a paradigm in your field to presume that access to early states of mind and emotions is always a good thing? Yeah, what he said. Yeah. Yeah, right on, I love this. Yes, so it's the case that we think that critical periods need to close. And that if you don't close them properly, you can end up with diseases of the brain. We think, for example, autism might represent a failure to close critical periods properly. Furthermore, we think that that's because if you've ever walked around like a forest with a two-year-old, you know that it is very difficult. They notice everything. They're curious about everything. They are solving problems in a totally different way than we as adults are solving problems. But it's terribly inefficient. Like you usually don't get very far. And if there was a saber-toothed tiger running around, you'd be, if everybody was experiencing the way that a child does, you'd be done, right? And so they need to close. It's less efficient. We need to eventually get into the mode of experiencing the world relying on our habit-based memories and our learned efficiencies for accomplishing different things. But if, for example, we learned something and it was adaptive at the time, but no longer adaptive. For example, let's say that you were a child and you experienced some horrible trauma, then you probably learned how to, in that moment, adapt to that situation in a very guarded learning to be hyper-vigilant about threats around you and not trusting people. And that was protective and adaptive at the time. But as you get older, and that threat disappears and you're now, you know, physically mature and able to defend yourself better, then those kinds of learned responses around your trauma are no longer appropriate. So what we're imagining is that the way that these psychedelics are helping for diseases like PTSD is that they are enabling a sort of reopening of that window of time when you learned so that you can reconfigure the memories and patterns of behavior in a way that is appropriate for your current circumstances. - But is that in tandem with the therapeutic phase of maybe some therapy, some psychiatry and not just a standalone? Just give them psychedelics, they'll be fine. - What are the accomplishments that are along with it? - Yeah, so this is another really cool thing about our mechanistic explanation for how psychedelics work is that we have known for decades that, and actually Timothy Leary is one of the first psychologists who described it this way. He said that psychedelics effects are dependent on the set and setting. And what he meant by that is the mindset that you're in when you take them and the setting that you're in, who else is around you when you take them. And that can have a huge effect on whether you have a good trip or a bad trip, whether or not you have a therapeutic effect or whether you have something like, you know, you hang out with Charles Manson and you end up murdering people because you think you're accomplishing something great, right? So that context dependence of psychedelics effects has been known for a really long time. And what we discovered is that critical period reopening with psychedelics is also context dependent. So if we give MDMA, for example, in a social context, we can reopen the social reward learning critical period in mice, but if we give it in an isolation context, we don't open that critical period. And what I think that's analogous to is, if you take MDMA and you go to a rave, maybe you're reopening a critical period for socializing or dancing, but it's not gonna be the right kind of environment for unlocking those traumatic memories and trying to have a therapeutic effect, which we think requires a therapeutic context in order to achieve. - Wow, that's great. And let me just ask you just as an aside, what is it about ketamine that causes dumbass billionaires to think they know anything about running a government? (laughing) - You know, I'm not gonna answer that. I don't know, said dumbass, but billionaires, I just, what I can say is that in general, psychedelics have this ability that's property called the noetic property, which was actually described by William James in the late 1800s. - Huh. - And that noetic property means that when you take a noetic property is that that feeling that what you're experiencing is the really real. Everything else up until this moment was sort of a limited view of the world, but now that I've had this experience, now I really, really know. And that noetic property is part of, I think we think it's important for achieving the therapeutic effects of psychedelics. It's also probably appropriate when you're a child to have this kind of approach to everything that you learn. Like, this is it, I know it now, and I can really lock in this memory, but it's also potentially, if it's misused or misunderstood, or if you aren't aware of the seduction of that kind of, I really know now, you can end up believing that you understand or know more than you do, which is why I think that we have to be sort of careful about the potential for using these compounds and then ending up with sort of narcissism or potentially sort of a messiah complex. - By Apollo 14, Astronon, Edgar Mitchell, upon returning to Earth, later on, would create the noetic institute. - Oh, what? - That's right, here's what happened. On his way back from the moon, okay, okay. He was positioned in the capsule in such a way that the rotation of the capsule was in the same plane as the plane of the solar system. So that as the capsule turned, he would see in sequence the Earth, the moon, other planets, the sun, and that would repeat the entire three days back to Earth. - Wow. - And so this experience, he kept thinking to himself, am I getting a deeper understanding of reality by this repeated exposure to something no one ever would otherwise get to see? And so he was certain afterwards or at least confident that there was some state of mind beyond what our normal reality was that might be achievable when you're exposed in this way as he was. - Ah. - And I'll tell you his own, the solar system was his evil game. (laughing) - He was going to universe him fit. - That's what, yeah, he was rotating like, I'm high as hell right now. - Yes, essentially. - Yeah. - Yes, that was his, transcendent state of mind. That was the first time I'd heard the word, or seen the term, "No, I didn't know what it meant." And you're reaffirming this belief that you have achieved something that no one else has. So therefore, we all must come to you for the answers. And it's Edgar Mitchell's quote that I've opened one of my books with, which is you develop an instant global consciousness, a people orientation, an intense dissatisfaction with the state of the world and a compulsion to do something about it. From out there on the moon, international politics looks so petty. You want to grab a politician by the scruff of the neck and drag him a quarter million miles out and say, "Look at that, you son of a bitch." He got angry, didn't he? Earth floating in the air. Wow. Yeah. That's the same guy who started in a way to constitute it. Yeah, what's the same? And listen, I'm with him. That guy's awesome. That's awesome. That's, that's pretty, that's, he's feeling it. Yeah, he's feeling the positive and the positive. That is intense, but deservedly so. Yes, yeah, yeah, yeah. So when we reopen these critical periods, can they be beneficial for resetting, re-educating, giving us a better look at maybe the sciences, maybe the astronauts? No, I love it because the universe. I'm not high. I'm just trying to get better at calculus. Yeah, absolutely, absolutely. This, this critical period idea certainly extends beyond the notion that it only could be useful for therapeutic properties, but, you know, also for improving our ability to learn new things when we're adults, right? So once our critical periods have closed, you know, the adage you can't teach an old dog new tricks, you know, the idea here is that if you take psychedelics, well, maybe you can. And so, yeah, if you had something that gosh, you know, I, for example, I struggle with learning languages. If I wanted, you know, in theory, the idea, if this turns out to be true, is that, you know, we would be able to use this for all types of learning, not just learning around neuropsychiatric illness like PTSD. And in fact, actually, you know, one of those ways that we are testing this idea of, you know, the generalizability across lots of different critical periods is that in collaboration with my colleagues at Johns Hopkins, Steve Zyler, and, you know, the team of neurologists and occupational therapists that we are working with, we are using psychedelics, in this case, psilocybin, to try and reopen a motor learning critical period for people who had stroke. And so, after you have a stroke, your motor learning critical period opens for about a month or two months, and then it closes. And so, whatever physical therapy, whatever occupational therapy you get within that first two months after you have a stroke, that's kind of it. Like, whatever improvements you get after that time, that's it. But for a lot of people, it takes, you know, that after that is closed, those people still have motor deficits. And so, the dream here is that, you know, we could go back a year out from the stroke when they're no longer able to get any motor improvements anymore, and give psilocybin parat this time instead of with psychotherapy, with physical therapy, with occupational therapy, and now the therapeutic context, this motor learning. And can we get, you know, improvements in motor function and rehabilitation? You're taking care of the mind and body. There you go. So now you've, now you've made me think, can you replicate this sort of practice with dementia patients, with Alzheimer's sufferers, or is that just one step too far right now? Well, right now, what it looks like is that, unfortunately, this mechanism doesn't really suggest a way that it would be useful for Alzheimer's or Parkinson's, or any of the neurodegenerative diseases, because it doesn't cause neurons to regrow, it doesn't cause neurons to be born. And those neurodegenerative processes are unlikely to be interrupted. So even if you could use psychedelics to get some kind of, you know, motor therapy to help Parkinson's patients, you know, regain some of the functions that they lost by teaching them alternative pathways for, let's say, swallowing or moving, the neurodegenerative process is going to continue. And so we don't think that they will be that therapeutically useful in those cases. I just have one question about the, when you're talking about learning things or when you open a window. So I read that I forget the particular period, but cocaine was used in marriage therapy, you know, and couples therapy, which is not a good idea. However, could you use these psychedelics to reopen a period where the chemical attraction between two people was greatest and kind of spark a re-ignition of their romance so that they're more open to, you know, receiving one another. You're asking for a friend. Yes, of course. No, I'm not. It's my wife hates me. Like, let's get it. Let's get it. Don't get it twisted. Now, yeah. Yeah, well, I mean, Alexander Shulgen, who is the chemist, who is most frequently associated and who he did the first sort of scientific characterization of MDMA, but also invented hundreds of other psychedelics, he loved MDMA and was particularly enamored of the idea that it could be used exactly for that for couples therapy. And so, I think, and his wife, Anne Shulgen, was a therapist. And in fact, before MDMA became a schedule one drug, it was actually used legally by psychotherapists for helping people be able to explore conflict in a very open and honest and vulnerable way that was especially useful for people who were having difficulty communicating with each other, for example, in couples. Not so much as a, you know, aphrodisiac, but more as a way of being vulnerable and open to get past conflicts that are ordinarily too scary or too, you know, that you might not say because you'd be afraid of hurting somebody's feelings, but to be able to be open and vulnerable in this way seems to be one of the-- Well, I'm a sensitive guy, so vulnerability is an aphrodisiac to me. Absolutely. I think that's right. That's right. No, that's right. I think that, you know, people who focus on just sort of the immediate attraction rather than the importance of these kinds of more vulnerable states for building long-term trust and being able to really communicate. This is, this is what sets apart love and lust. And I think that it's better to-- I think it's more appropriate to think of psychedelics as fostering this type of behavior, this altered state called love. And, you know, I could do a whole podcast on the different types of love and oxytocin neurons and the subtypes for different subtypes of love, but-- Now you tell us. That's what we would-- But done this podcast on. Okay, go on. Yeah, I mean, I, you know, when I first started my lab, one of the things that we really worked on was trying to figure out the different subtypes of oxytocin neuron, and we discovered that they're, you know, the big oxytocin neurons that are important for what I, what I call like, mad love, like falling in love with your partner or falling in love with your baby, and then sort of platonic love that are encoded by oxytocin neurons that are smaller, release smaller amounts of this pro-social peptide oxytocin, and are really important for things like being able to form communal attachments, knowing who to let into your friend group and who not, and also, you know, encodes love in a much more guarded and nuanced way, and it seems that those two types of oxytocin neurons have evolved in parallel in species that do more or less of this hair bonding type of love. Hello, I'm Vinky Brook Allen, and I support Star Talk on Patreon. This is Star Talk with Nailed Grass Tyson. And again, A, you know, it's a rock star. B, what is it? And what are its origins? Yeah, so I began is a psychedelic that, you know, I can divide up psychedelics into different categories based on their acute subjective effects. I began as what is called an oh, nirogenic psychedelic, meaning oh, nirogen just means induces a dream like state. Dream. Yeah. And so, you know, typically when people talk about, I began trips, they're talking about, you know, this dream like state that feels very much like you're doing a history of your life in a slideshow or like a dreamscape. People do life reviews. People talk about how important those life reviews are for their ability to understand whatever psychological issues that they are having. I began comes from a, it's a, it's a chemical that is synthesized from Iboga, which is a chemical that comes from the tabernathy Iboga plant. It's a tree and the, the Ibogaine is concentrated in the root and the bark of that tree. It found where, where, where do you find that tree? It's found in Gabon, mostly in Africa. And it is traditionally used by the Buiti tribes. And it's used dates back, you know, we, we depending on which sort of standard you use and this is, you know, definitely not my field, but, you know, anthropological evidence suggests that it is been in use continuous human use for, you know, at least a thousand years probably more than that. So it says, you know, humans have been using Ibogaine for as long as, for example, psilocybin. Those two are probably the two oldest psychedelics that we have, historical anthropological evidence that people have been using them. So, yeah, and it's different from other psychedelics in so far as, you know, the trip is very, very long and it has been especially interesting because it turns out that the veterans who are dealing with a huge amount of PTSD and depression and suicidality are tracking down to Mexico and other countries to use Ibogaine to help treat their PTSD and their addiction and their depression. Is that because it's viewed as an illegal substance here in the U.S.? It is an illegal substance. It's a schedule one psychedelic and so it is not used therapeutically in the United States, but in Mexico, the legal status of Ibogaine is a little bit more unclear. It's, it's basically not illegal, but it's not totally legal either. And so who establishes these levels of drugs? The Control Substances Act of 1970 is what established psychedelics, including Ibogaine as a schedule one drug and it is regulated by the DEA and the FDA. But because of this incredible therapeutic promise of Ibogaine, you know, Americans for Ibogaine has done an amazing public awareness campaign and also legislative campaign to try and use some of the money that came to governments for reducing or addressing the opioid crisis. Starting first in Texas, what they were able to do is get legislation passed that and it unlocks state level money to do research on Ibogaine for addressing, you know, sort of the opioid crisis in this country. And most recently, the Trump administration has acknowledged that this is a priority for them to try and get these medications, you know, research. I will say Ibogaine. I just want to be careful about Ibogaine though, as powerful as it is and is sort of remarkably effective, the evidence, the anecdotal evidence and sort of this, you know, in the clinics in Mexico kind of evidence to suggest that it's useful for opioid use disorder. Ibogaine is a little bit, I mean, it has cardiotoxicity, meaning that if you take it and you have a pre-existing heart condition, it seems that, you know, you need to pair it with something that can stabilize the heart like magnesium in order to overcome this cardiotoxicity. So the FDA and the DEA are very interested in supporting this research, the National Institute of Drug Abuse actually just gave a group at Harvard $11 million grant to work on a phase one safety study for Ibogaine. And that is going to be really, really important to determine whether or not we can eventually use this medication clinically for opioid use disorder. Oh, that's great. So these, many of these rules are 50 years out of date, is the point. And somebody needs to get in there and at least review it every decade or so. I mean, there's got to be some sensible way to keep you guys, your labs active and vibrant in the effort to explore these connections. That's right. And we are, you know, very excited about the possibility that, you know, maps, you know, you guys had Rick Doblin on this show a couple years ago, maps as an organization that spent the last 40 years working on trying to provide the clinical data to say, you know what, these drugs don't belong in schedule one because they do have therapeutic efficacy. And it's looking very hopeful that that approvals for MDMA and psilocybin may come through as early as this year. But we're all sort of waiting. I hope so. What's in marijuana a schedule one at some point? What am I, am I remembering that correctly? And then, yeah, it was without doubt. So when you, that was because they were convinced that black people were using it. Right, right, right. And I was like, you know, we got to do something about these jazz musicians. You know, they're playing them. Well, no, it's all over the place. It must be high. Well, you know, a little white kids will love jazz. Yeah. So, yeah, if it's, if it's disproportionate usage in the black community, then you get to arrest them, but not the alcohol abusers that are in the white community. Yeah. And then you have a disproportionate, a bit of disproportionate importance of people going to present them with crack cocaine and regular cocaine. Right. You know, crack cocaine, you know, you go to jail for a lot longer. Why? Because there's a disproportionate use in black community. Yeah. You know, however, I will say this, what's great about what you're doing, what has to happen is people have got to understand that in general, no one wants to be addicted to drugs. That's right. Period. Like full stop, we got to get over this whole notion in this nation. And it's the pretty much like the only nation in the world that does this where we look at people whose brains have been hijacked by a substance. And we say the treatment for that is to throw your ass in jail. It is the dumbest fricking thing in the world. And if we, if we divorce ourselves from that philosophy, then it will free us to go ahead and explore ways that we might deal with the problem to help people and solve the problem at the same time. Chuck for president. Yes. Before we sadly have to let you go, Goal, I must ask you, studying psychedelics, does it affect your relationship with reality? Thank you for asking that. Yeah. With objective reality. Wow. Right. So true. I like that objective reality. Yeah. I mean, I often end up on panels especially within the psychedelics community where, you know, there are four of us on stage and three of them say, Oh, yeah, you know, psychedelics reveal that, you know, it pulls the curtain. And now I'm able to see the really real. And I now I know that there's a reality beyond the physical world. I am a biologist and an evolutionary, you know, I see things in terms of evolution and biology and physicalism. You know, I started my career as an undergrad. My major was sponsored by the philosophy department and it was called comparative perspectives on the mind. And I really sort of considered all different philosophical views on this. And I have to say that for me, the study of psychedelics has convinced me even more that we live in a physicalist reality and that the very fact that you can take a molecule, put it in your mouth and have that molecule essentially mimic another molecule that's in your brain already. And then drastically alter your perception of reality and consciousness tells me that what we think of as consciousness is just the manifestation of two molecules interacting with each other, and that the universe is explainable, even if we can't do it right now in terms of physical reality. - Oh, you will, you're great at a party, aren't you? (laughs) - God! - I know. - It's for bringing me down. - No. - I know, I'm gonna get that. People are like, you're killing my dream, you know, but I can't do it. - No, cool. No, you're my hero, you're cool. - No, Neil's over here. - I'm loving it. - From ear to ear. - No, no, cool. But I've always said that to the brain barely works enough to decode objective reality from that, which is not, it barely succeeds at this. So to stir in some chemicals and then say, oh, now I can see it better, I don't get that. - It could be an augmentation, Neil. It doesn't necessarily have to be a detraction. - I mean, I think going back, though, to this notion of the noetic property, right? Like, it is a, every, I wouldn't necessarily frame it as the brain is barely working. Rather, I would say it's that we are interpreting the universe through our sensory modalities and this, everything that we see was evolved as a response to what was required to adapt and survive as an organism. - To not die. - To not die, right? And so, to me, there is potentially a reason why we would want to reopen critical periods. So I'll give you another example. We have known for many, many years that you can reopen critical periods by doing deprivation experiments. So in mice and humans, this looks like, for example, if you wanted to reopen the visual critical period, you can blindfold somebody for two weeks or blindfold an animal for two weeks and then it'll reopen the visual critical period. And when you do that in humans, that experiment, it causes mystical experiences and hallucinations that are phenomenologically very similar to psychedelics. And we know that mystical traditions and religions have used this sort of deprivation type of experiment for a millennia to achieve mystical states, going and living in a cave for a month or what the Zen Buddhist called beginner's mind. I mean, if you're looking for a neurobiological description of beginner's mind, critical period reopening is it. And so in my view, the sort of phenomenological overlap between psychedelic mediated critical period reopening and deprivation mediated critical period reopening suggests that what it feels like to be in this altered state of consciousness is just what it feels like to reopen critical periods. And I think that the reason that these things exist, like why does the brain need a mechanism for reopening critical periods? If it's so important that we close them, why would we ever want to be able to reopen them if we're an ancient person, why would we do it with a psychedelic or a religious practice? And I think the reason is because learned habits of memory are very useful so long as your environment is stable and you're exposed to rules that you can follow and easily navigate the world following your sort of trained habits of thought and behavior. But imagine if something radically shifts in your environment, so if you're a mouse, if your whole mouse colony gets eaten by a wolf or if you're a human and you move to a new culture where nobody speaks your language, these would all be circumstances where your brain would probably want to hit the reset button and say, you know what, the statistics of the world that I'm in right now are changed and I need to relearn for the environment that I now find myself in. And so I do think that these altered states are not really a broken brain so much as a brain experiencing a radical shift. Kind of like if you and I were having this conversation and the video started flickering, we might not do anything with the flickering, but if it froze for any amount of time, we would hit the reset button, reset the internet, reset the browser and try and go again. And I think that's kind of what the brain has evolved to be able to do when there are big shifts in the environment. - Can you repeat all that? You were breaking up. So I want to take this out. I want to take this out if I may. - So, Google, I'm still stuck on your octopus, okay? And 'cause we didn't really-- - That was an hour and a half ago. - I know, it was an hour and a half, how long ago? Let me just say that you already said, I did not know that octopus's are a social. So humans are generally not a social, we're very communal generally as a species for sure. So it seems to me as much as we all love us some octopus, especially after the documentary, my octopus teacher. No one, I'd love me some octopus, but as a next species to test, I don't see why you would glean any insights back into humans by treating octopuses other than have a hilarious time watching them react. And the reason I ask is, we already talked about not being able to teach an old dog new tricks for all the reasons you gave, why not do this on dogs? And then demonstrate that you can teach an old dog new tricks. And a dog is a mammal vertebrate. It's not a squishy, invertebrate, eight-legged creature that squirts ink or whatever they do, I don't think. Okay, so, wouldn't dogs in this adage can't teach an old dog new tricks? Wouldn't that be a more useful other animal to test this on rather than an octopus? - Dogs like meth. - Instead, they told you. Dogs don't like M-D-M-A, they like meth. (laughing) - Well, I will tell you, you know, this is an old debate in neuroscience. And in fact, I have to say, my lab studies humans, mice, and octopuses. And the reason for the octopus experiment is actually, it's not our idea. Jay-Z Young, who was sort of the great granddaddy of neuroscience meets etiology, was the first to propose this idea that if you want to understand how to build complex behaviors from synapses, molecules, circuits, you can certainly look at the human brain and then look at the most common closest relative. But another way to do it would be to look at an animal that is maximally different from humans, and yet still capable of these complex behaviors. And what advantage of that is that you don't have to get distracted by accidents of evolutionary history. So the best example of that is that an octopus doesn't have a cerebral cortex, it doesn't have a nucleus accumbens, it doesn't have a brain stem, it doesn't have an amygdala. None of those brain regions exist in an octopus, and yet when you give them MDMA because the molecular similarity is there, you can induce these complex behaviors that are very similar. And so that tells us that all of these studies out there that are doing like FMRI brain imaging and saying, oh look, I gave a psychedelic or I gave whatever, I had people play Tetris or whatever experiment they're doing and look, this part of the brain lit up, that kind of inference about the mechanistic relationship between those brain regions and those functions is a little bit misleading and that the true mechanism is really at the level of molecules and depending on the evolutionary history of the animal, they can use the sort of anatomical toolkit in whatever way makes sense for their evolutionary history, but you don't need a cortex to do it. - God, it just would've been really cool if you had an old dog and then you gave it your medicine and then it did a new trick. You could do that on the today show and then that would, you get all the funding and you wouldn't have to do that. Exactly. - Well, I sort of, I mean, I sort of did that in mice and I'm hoping that if we can show this in humans, then by doing the stroke experiment, then I think it will radically shift the way that we understand this mechanism and will really open up all kinds of other avenues of study and all kinds of other diseases. I mean, we are currently, for example, also interested in, does an octopus even have a critical period? Do they, you know, just to challenge this notion, like what are critical periods good for? You know, an octopus is able to regrow its limbs if you cut them off. Sometimes they cut them off themselves. There are some species of octopus that are so asocial that the male in order to mate with the female just dislodges his sperm delivering hecticodilus arm so that he doesn't get eaten. And then he can regrow it. And so maybe they don't need critical periods in the same way that we do. And in fact, if they have some sort of novel, you know, innovation in their genetic code that enables them to do that, we want to know about it so that we can, you know, sort of co-opt their superpowers if having those superpowers doesn't come with some other, you know, risk or downfall that we don't want, right? And so we want to understand them. All I know is this, if you're ever with a woman who makes you have to dislodge your hecticodilus arm, you are with the wrong woman. I do have to say working with Octopus is fun because they are unlike mice, which are sort of, you know, the potato chips of the animal kingdom, right? Everybody eats them. So- The tasty snacks. Yeah. So when they get scared though, they, you know, they do, they are sort of obligate stoics, right? So they don't have much of a response. They freeze. They kind of cower in the corner. When you do something an octopus doesn't like, it will squirt you with water or ink. And it will let you know. And I sort of, I like that they have attitude like that. It feels, you know, they're more similar to us. And that is why actually I think that there is such an instinct to anthropomorphize around octopuses and to sort of imagine that they're like as smart as us because they sort of occupied the same top predator role in their habitat. And so we have a tendency to see a lot of ourselves in them. But I would just ask everybody to exercise some caution about that kind of anthropomorphizing because, you know, the truth is, compared to a mouse, you know, we are olfactory morons. Well, even dogs, yeah. Yeah. Yeah. Exactly. Yeah. Not to mention bears, please. Yeah, but not only that, if an octopus wanted to imprison you, right, it would just need to put you in a room with a door that has three door knobs. You would never get out. It could easily just open it up. Oh, that's funny. Well, you know, an Aristotle thought that octopuses were the dumbest animal because they were easy to catch. All you had to do was dangle a piece of, you know, something shiny in front of them. And they would reach out and explore it. And then you just lift that shiny thing out of the water. And so he thought they were just dumb. And you know, by that measure, you know, humans are pretty dumb too. You just dangle a couple of, you know, dollars in front of them and they'll go chasing. No, you know, Aristotle got almost everything wrong in the physical science. Tell me. So, yeah, you have no hero worship about him from me. Yeah. Well, thank you. And we understand you were going to be with us in person, but the sea gods, Neptune and Poseidon got in the way. The storms closed Newark airport. And so thanks for joining us from here. You've been holed up in a hotel in Chicago. In Chicago. Well, thanks for joining us nonetheless in spite of those challenges. Thank you very much. It's been great. And how do we find your lab online? Is it how do we track what you do? So my lab is at Dolan Lab, D-O-L-E-N-L-A-B dot O-R-G. Oh, cool. Dolan Lab dot org. There you go. All right. Okay. Thanks for joining us once again. Thank you. All right. So this has been another installment of StarTalk Special Edition. Yeah. Chuck, thanks again. It was very nice. Gary. Pleasure, my friend. Always having you guys here. Neil the Grass Tyson as always. Keep looking up.

Podcast Summary

Key Points:

  1. Psychedelics reopen critical periods in the brain, restoring neuroplasticity similar to early childhood learning.
  2. This neuroplasticity is shared across different psychedelics, despite varied receptor bindings, converging on extracellular matrix remodeling.
  3. The duration of the reopened critical period correlates with the length of the psychedelic trip, with longer trips (like ibogaine) extending benefits for weeks or months.
  4. Critical periods are essential for learning and behavior, and their closure in adulthood limits adaptability—psychedelics may allow reprogramming of traumatic or maladaptive memories.
  5. Therapeutic effects depend on context
  6. Research shows potential applications beyond mental health, such as stroke rehabilitation and language learning in adults.
  7. Octopus studies provide evolutionary insights, demonstrating complex behaviors without human brain structures like the cortex.
  8. The "noetic property" of psychedelics—feeling a deeper reality—may foster vulnerability, trust, and long-term connection, especially in relationships and therapy.

Summary:

The episode explores how psychedelics restore neuroplasticity by reopening critical periods—windows of heightened brain plasticity seen in early life. This process, observed across psychedelics like psilocybin, LSD, and ibogaine, allows the brain to rewire itself, particularly in treating conditions like PTSD and stroke recovery. The duration of the effect correlates with the trip length, with longer trips like ibogaine extending benefits for weeks or months.

Crucially, these effects are context-dependent: they work best in safe, supportive therapeutic environments, not isolated or chaotic ones. The research suggests psychedelics may help reframe traumatic memories by enabling emotional re-evaluation and adaptive learning. While the idea of "teaching an old dog new tricks" is highlighted, animal studies—especially with octopuses—show that complex behaviors can emerge without human-specific brain structures, offering evolutionary insights into brain function.

The episode also emphasizes the importance of context and emotional vulnerability, noting that psychedelics foster a "noetic" experience—of deep, real-world awareness—that supports transformation in mental health, relationships, and learning. Though promising, psychedelics are not a panacea; their effectiveness is limited in neurodegenerative diseases like Alzheimer’s, where neuron loss cannot be reversed. Overall, the discussion positions psychedelics as a powerful tool not just for therapy, but for reactivating fundamental brain processes that enable lifelong learning, resilience, and human connection.

FAQs

Neuroplasticity refers to the brain's ability to change synaptic connections. Psychedelics appear to reopen critical periods in the brain, restoring the brain's capacity for plasticity—particularly the ability to form new memories and learn—similar to how young brains function.

Critical periods are developmental windows when the brain is highly sensitive to learning. Psychedelics, such as LSD, psilocybin, and MDMA, reopen these periods by altering brain chemistry, particularly through effects on serotonin and glutamate systems, allowing for new learning and memory formation.

Yes, the opening of critical periods can last for days to weeks after the drug effects wear off. For example, LSD can extend the critical period for up to three weeks, while longer-acting psychedelics like ibogaine may extend it for at least a month.

Yes, research shows psychedelics can help treat PTSD and other conditions by enabling individuals to reprocess traumatic memories in a safe, therapeutic context, allowing them to reconfigure maladaptive behaviors learned during trauma.

While animals like octopuses don't have human brain structures, they still show behavioral changes under psychedelics like MDMA. This suggests that complex behaviors can emerge from molecular-level brain changes, not just brain anatomy, highlighting a universal mechanism across species.

The mindset and environment during a psychedelic experience—known as 'set and setting'—are crucial. A supportive, safe, and therapeutic context increases the likelihood of positive outcomes, while a negative or chaotic setting can lead to harmful or non-therapeutic experiences.

Chat with AI

Loading...

Pro features

Go deeper with this episode

Unlock creator-grade tools that turn any transcript into show notes and subtitle files.