Psychedelics: The scientific renaissance of mind-altering drugs | Sam Harris, Michael Pollan & more

MICHAEL POLLAN: How do these psychedelics work? Well, the honest answer is we don't entirely know, but we know a few things. One is they fit a certain receptor site: the serotonin 5-HT2A receptor. And they look a lot like serotonin if you look at the molecular models of them, and, in fact, LSD fits that receptor site even better than serotonin does and it stays there longer. And that's why the LSD trip can last 12 hours. What happens after that we don't really know. It's an agonist to that receptor. So it increases its activity.

And this, you know the neuroscientists say, lead to a cascade of effects which is shorthand for don't really know what happens next. But one thing we do know, or we think we know, is that it appears that one particular brain network is deactivated or quieted. And that is the default mode network. This was discovered not very long ago by a researcher in England named Robin Carhart-Harris who was dosing people with psilocybin and LSD and then sliding them into an MRI machine, to take an FMRI, a functional magnetic resonance image.

The expectation I think was that people would see an excitation of many different networks in the brain. You know, that's what the kind of mental fireworks sort of foretold, but he was very surprised to discover that one particular network was down-regulated, and that was this default mode network. So what is that? Well, it's a tightly linked set of structures connecting the prefrontal cortex to the posterior cingulate cortex, to the deeper older centers of emotion and memory.

It appears to be involved in things like self-reflection, theory of mind, the ability to impute mental states to others, mental time travel, the ability to project forward in time and back, which is central to creating an identity, right? You don't have an identity without a memory and the so-called autobiographical memory, the function by which we construct the story of who we are by taking the things that happened to us and folding them into that narrative. And that appears to take place in the posterior cingulate cortex.

So, you know, to the extent the ego can be said to have a location in the brain it appears to be this, the default mode network. It's active when you're doing nothing. When your mind is wandering. It can be very self-critical, it's where self-talk takes place. And that goes quiet. And when that goes quiet, the brain is sort of, as one of the neuroscientists put it, let off the leash, because those ego functions, that self idea is a regulator of all mental activity and kind of, you know, the brain is a hierarchical system and the default mode network appears to be at the top.

It's kind of the orchestra conductor or corporate executive. And you take that out of the picture, and suddenly you have this uprising from other parts of the brain and you have networks that don't ordinarily communicate with one another suddenly striking up conversations. So you might have the visual cortex talking to the auditory system, and suddenly you're seeing music, or it becomes palpable. You can feel it or smell it and, you know, synesthesia.

So you have this temporary rewiring of the brain, in the absence of the control of the regulator. And this appears to have, you know, a beneficial effect in terms of jogging the brain out of bad patterns.

SAM HARRIS: The truth is virtually any experience you can have with psychedelics you can have without psychedelics. Because all psychedelics do is modulate the existing neurochemistry of the brain. They're not doing something that the brain can't do on its own, you're just playing with neurotransmitters or mimicking neurotransmitters.

I have had the same experience to a more or less similar degree just through meditation, but it's clear to me that I would never have suspected that such an experience was possible but for my experimenting with MDMA in the beginning and it had not been adopted by popular culture as a party drug. So this was coming very much out of the therapeutic community. People were doing in a closeted way...