The Brain on Psychedelics | Hacker News Reader

The Brain on Psychedelics

nature.com

132 pointsbenbreen73 comments

Being on Psychedelics and being strapped onto an MRI machine where I couldn't move sounds terrible. There is some definite measurement problems going on with a study like this.

MRI machines are the stuff of nightmares for me, I can't imagine the hell that would be.

Depends on the model though, on small one where there's really no room around your head, which is locked in a cage is really edging on psychological torture depending on your anxiety level.

Psychedelics have caused heavy anxiety for me even when sitting next to a beautiful mountaib stream. I've had a panic attack in an MRI while sober. Couldn't imagine doing both at the same time.

Might just wipe those fears out of your mind if you were in the right mental space and coached through it. As I understand it, this is showing promise in treating the kind of panic attack/PTSD trauma you're describing. I only mention PTSD because it's been a problem for some of my friends and they are very interested in the positive news about psychedelics as treatment options.

From my perspective, a long acting treatment done via psychedelics and a guide, in a controlled environment, with no need to repeatedly take a drug and no day to day side effects of that drug (because, you're not taking one) is incredibly promising. Unfortunately, this is exactly the kind of treatment that the business behind medicine doesn't like, so I'm quite skeptical if it's ever brought to market.

I had an hour long (ish, maybe a bit longer?) brain scan in an MRI for a control in a phd friend's study. I snoozed and the only notable thing was me sleepily snapping at her for waking me up to tell me what was happening...

The ear defender/headphones were pretty great

Same for me (and plenty of coworkers who took part in the same studies) -- hardest part of taking part in the fMRI experiments was staying awake through it.

To everyone reading: There is a cage on your head if you get a scan of your head. But if they are looking at your abdomen, you'll find a different sort of device over your midsection. I'm guessing that they have stuff for other parts as well.

I don't personally mind the cage, and a lot of models have a mirror so that your field of vision is greater than the tube. (I get regular MRIs due to MS and a pancreas cyst)

Apologies for not being precise :)

Huh this just made me realize I never keep my eyes open in the MRI machine. (I also have MS). Now I'm wondering which is more common.

I keep my eyes open as they put me in the tube, and close them when the test starts. I'm always afraid that I'll think something looks interesting and move my head while trying to see it. I might find an MRI relaxing, but I still don't wanna do it twice.

I hate when I have to do them twice. I twitch a lot. It's the worst, and I'm uncomfortable, and the tech is stressed because it screws up the scheduling and ugh it's just the worst.

Or when I have to pee in the middle.

Yes these are the coils used for excitation and reading. But really what you hear are the gradient coils inside the magnet assembly.

I was wondering if the inconsistent outcomes they were talking about could be due to environemnt/scenario influence. Like how people have completely different experiences based on their mindset, environment, etc prior to taking the drug. In my stupid mind, it's as if the drug doesn't have simply one effect, but enhances whatever is there already. Sort of like how some medications have different effects at different doses or in combination with different medicines.

I have never been in an MRI but I imagine with some good headphones and blindfolds it might be interesting.

Doubtful. It’s not comfortable, you can’t move, and it’s extremely noisy to the point that no headphones would be able to drown out the mechanical sounds that would ruin a psychedelic experience

I dunno. I have to get MRIs regularly: Once a year for my central nervous system (I have MS, this is common) and once a year or so for my pancreas.

I don't mind at all. I have to stay alert for the pancreas since I have to hold my breath at one point, but all I do for the brain/spinal cord is lay still. The machine vibrates, headphones dull the sound, and sometimes there is music. I could sleep and I find the vibration kind of soothing - much like being in a car.

I kinda look forward to it, honestly.

I’m not saying that the MRI experience itself is unbearable. But have you ever done psychedelics? No sleeping/snoozing. Your mind is very, very active and it can be intense/emotional. The experience I’ve had with MRI and shrooms/LSD makes them seem very incompatible. Just my opinion though.

I don't know. Mushrooms make me want to stay as still as possible in whatever position I'm in, even if it's standing. Unless the person suffers from claustrophobia, I don't think it would be an unbearable experience.

It is possible to sort of sleep on psychs. I guess it's not quite sleep; it's more like a relaxed state of altered consciousness within the "normal" state of altered consciousness. I sometimes become alert again and realize I dozed off for a few minutes without losing track of time.

I've done more psychedelics than I remember. I know I've done LSD at least 35-40 times over the years, and it has been less than 3 months at this point. I'm over 40, by the way.

I can sit there with my eyes closed while on LSD. Same with mushrooms. Mushrooms are a bit more fun with that because of the visuals and patterns - I've spent some hours like this in a hotel in Amsterdam (truffles, obviously).

I already find an MRI relaxing - they give you a button in case anything goes wrong, after all, and they can put music in the headphones. I can definitely just relax there and I can definitely see how it would be pretty immersive. Plus, I'm pretty sure they aren't giving these folks contrast through an IV and that's really the bit I'd have some issues with.

MRI days = free rest days. So relaxing.

I mean, you go into it knowing you're high and doing this for a medical study, so the experience of the setting can be reframed by the right (mind)set. Duty and higher purpose do a lot to change one's mentalities.

Our participants fall asleep quite regularly. In fact, it's a well-known problem in MRI research.

It's *VERY* loud. You can't wear conventional headphones, you'll need non-magnetic headphones that are made specifically to be used during MRI scans. That means no active noise canceling features. The MRI is loud enough to be heard through the passive attenuation of headphones or earplugs, so you'll still hear the mechanical beat of the MRI underneath any music.

Oh you could make noise dampening and cancelling headphones for MRI with nonmagnetic piezo transducers. Ear canal earphones would help with it too by cutting the noise some 30 dB.

The problem is that the noise made by the machine is loud sounds comparable to an explosion or a gunshot. You can reduce it but never fully cancel it, and it's rather startling.

There are styles of headphones that are like an ear plug (to reduce noise by say 20db) that have a small tube running to the driver that is a long distance away. They’re these clear tubes with a coil you see on security guards and what not. The actual driver is somewhere else.

This could also be used. I think some in ear monitors are like to too.

When I was looking this is exactly how MRI headphones worked. Just with a much longer tube

Noise dampening? Yeah plenty exist. There's a hard limit of about 30db reduction passively unless you also plug your mouth, nostrils, and wear a helmet around your skull. But noise reduction/dampening does not mean the same thing as active noise canceling.

For ANC you need a microphone very close to the ear and some sort of chip to process that and apply it inversely to the speaker. There would just be too much delay if the sound waves have to make a round trip more than a few mm

And you will have a phase problem because of the delay of transmission. And the phase of the noise is not predictable that well (the RF that cause it is really precise, but the physical movement of the coils and everything around them is not).

I honestly don’t think it would be that bad. Let’s say your actually only in the machine for an hour or so during the height of your trip. To me, an MRI scan sounds almost like a deep house or techno beat. It might even be enjoyable. The worst MRI scans are ones done with contrast - having a thick needle in your arm really ruins the MRI experience for me.

can we design MRI scan with a programmed physical (movnig) noise absorbing panels so the sound actually becomes rhythmic or even jazz like: https://www.youtube.com/watch?v=WqpEQWRcQcw

Even better, match up the sound to a song with a similar BPM and create an analogue techno mashup set.

I actually kind of like an MRI. The rhythmic pulsing is relaxing.

But obligatory relevant xkcd https://xkcd.com/1453/

> Our fMRI study found that subjects performing simple memory tasks showed activity in the parts of the brain associated with loud noises clautrophobia, and the removal of jewelry.

I actually kind of like an MRI. The rhythmic pulsing is relaxing.

Same, very much so. I often lament that a voice comes through and talks to me.

I thought I was the only one, great to hear others enjoy them also.

Using an Upright MRI [0] (created to help claustrophobic patients and is relatively open) might help.

[0] http://www.uprightmrideerfield.com/5-reasons-to-choose-uprig...

I have fallen asleep in MRI’s everytime. I find the experience incredibly relaxing. I also am very sensitive to mind altering substances.

Go figure

Try being strapped to a hospital bed in foreign country experiencing the most traumatic hallucinations and unending loops that are beyond the imaginable. Do not fuck with strong acid.

From my experience with psilocybin-containing mushrooms, I didn't hallucinate. Rather, my senses grew incredibly sharper and everything was super-vivid. I could see why they would be great for hunting in a prehistoric setting and would give one an unfair advantage. Shrooms are even known to increase visual acuity. It was like watching 4K video for the first time after watching standard definition your whole life.

As for my mind, I had what people call a 'mystical experience' but I was so young (20s) that I didn't have the necessary words to describe it or put it into words. It's only when I read up about Gnosticism and went down various conspiracy theory rabbit-holes on Youtube that I could piece it all together, and have the right words to describe it (escaping the Matrix etc).

I would never try them again though. Too risky. I value my mental health too much. If I want shroom-like hallucinations though, I use the Lumenate app which everyone should try...

https://lumenategrowth.com/

I doubt they actually increase the quality of perception, they just make you feel like you can see more clearly. That would be an interesting study to do, though, whether people on psychedelics can see things differently in an externally measurable way. A different sort of study has been performed that measured that people who had used psychedelics in the past were less able to see strobe lights at certain frequencies than people who had never used them, with people who suffered from HPPD being even more impaired.

Apparently there have been no documented cases of schizophrenia found in people who've been blind since birth. It would be interesting if someone explored the relationships between the effects of psychedelics and those with another kind of blindness, Aphantasia and those without.

This reminds me of a site I came across that uses the properties of a trip to show psychonauts messages that sober humans would find more difficult to interpret: https://qualiacomputing.com/2015/05/22/how-to-secretly-commu...

One thing I noticed one time on mushrooms was that certain scenes in video became absolutely incomprehensible. Modern codecs save space by basically "smearing" pixels into areas of similar color. On mushrooms, I was only able to perceive this smearing, and so a scene of a character walking down a hall just looked like an amorphous blob floating across a pool of paint and leaving a wake of color turbulence behind it. I could only tell what was going on by really concentrating and inferring from context. I can't remember if pausing made any difference.

I doubt it, but I wonder if it would be possible to perceive a merely audibly compressed audio stream as being completely garbled.

hey that is wild

Don't blame the video codec. You can observe similar artifacts on non video stimuli. Psychedelics reveal how the brain works, and the brain probably compresses information similar to a video codec.

I completely agree that psychedelics make the functioning of the brain (and I would argue the whole nervous system) more obvious. Given that they cause subnetworks that don't normally communicate, to communicate, and vice versa, I interpreted it as two steps in the visual pipeline talking directly to each other when they would normally have to go through a separate network that processes motion. Or perhaps signals from an unrelated network filtering into the pipeline and messing with the interpretation of the visual input.

Obviously video codecs should be optimized for sober psychovisuals. It would be wasteful and impractical to do otherwise.

I think discrete pipelines is the wrong paradigm. I surmise what is happening is the incoming information is being changed to the frequency domain for much the same reason that many visual and audio filters are implemented in the frequency domain. It's just a convenient basis for signal processing. It also so happens that compression codecs work largely by also converting to frequency space and then throwing out all the terms with negligible amplitude. So obviously when you poke at the part of the brain that does visual signal processing, you get something that looks a lot like a Photoshop filter or a compression artifact.

Unlike hearing, I don't think the visual system works in the frequency domain. Common psychedelic visual hallucinations are better explained as either transformations in the space domain, or stages of a pipeline being reconnected in odd ways. As an example of the former, a sharpen filter can be implemented as a simple convolution, which would be compatible with crosstalk in the neurons processing the "pixels" of the visual input. Of the latter, fractals are a common theme in hallucinations; they can be explained as feedback loops in a pipeline, where the signal ends up making several loops through a few processing stages. The sharpen hallucination might also be caused like this. Perhaps the brain already applies a sharpen filter and what happens is that it's applied multiple times to the signal.

I think you might have missed out on learning about the 2d Fourier transform and the meaning of "frequency domain". The standing wave patterns of the feedback loops are exactly the wave patterns you want to decompose the image data into. The waves have a characteristic frequency inversely proportional to the length of the loop. One can apply a decomposition into a wave basis just as easily on the space domain as one does on the time domain. The convolution in the original domain just becomes multiplication in the frequency domain. Sharpen and blur filters are literally just high pass and low pass filters applied to the 2d Fourier transform.

I highly doubt there is one big pipeline to which the original sensory inputs go through some fixed filters and then return back to the main start point as feedback. It's not exactly like pointing your camera at the projector, or holding the microphone too close to the speaker. Rather, there's many possible paths for neural inputs to loop back, and none of these loops is the dominant "pipeline". It's more like a microphone is near a whole wall of speakers, each with its own characteristic delay and amplification factor. The repeating spatial patterns of whatever length directly translate to a standing wave in neural loops with the right amount of loop length.

The transform to a convenient wave basis doesn't need to be implemented as a layer in a pipeline because the loops themselves are the transform.

A transform into frequencies (in some weird basis) is almost an unavoidable consequence of connecting neurons at random. Just like any old metal sheet is a bell if you hit it with a hammer, any old clump of neurons is going to have standing waves of activations that resonate with some sensory input pattern.

If you randomly poke at some neurons, possibly altering their delay time or adding/disabling connections, statistically the longer the loop the more likely it is to be affected. This view also nicely explains the other effects of LSD. Your sense of time is wrong for the exact same reason your perception is distorted: the timing of all the loops have been slightly detuned.

What strikes me as unconvincing about interpreting vision as operating on the frequency domain is that anyone can look as a sound wave's spectrogram and understand what it's representing, even if they're totally unfamiliar with graphs in general. I've looked at spectrograms and noticed sounds that I was missing, then looked for them at the right times and frequencies and found them. You may not be able to understand the sound from a spectrogram (e.g. understand words, or melody), but you can understand what it's representing.

If you look at the 2D FFT of a bitmap, the result is completely incomprehensible. You could look at two videos and their corresponding 2D spectrograms side-by-side and not know which corresponds to which.

I share your doubt, but one thing I dare say is that they make you more likely to spot things in your peripheral vision that would otherwise go unnoticed. Things stand out more, small differences are enhanced.

Also looking at a paper I could see the fibers it was made up of, not sure if that was real though.

They do apply a subjective sharpening (literally like an image processing sharpen filter) to the entire field of vision, and they also enhance pattern recognition, and so details that might be more difficult to see stand out. But on the other hand, they also make it more difficult to concentrate, and they also make you see patterns that don't actually exist. So it's difficult for me to imagine anyone using them for immediately practical purposes successfully.

So they are essentially like a "sharpen" image filters.

Sharpening filters don't actually sharpen an image, you would need deconvolution for that and it is really hard to do and require accurate knowledge of the process that made the image blurry. And even the best algorithms can't recover information that wasn't here in the first place.

What sharpening filters do is that they increase contrast locally, so instead of having light grey -> dark grey, you have light grey -> white -> black -> dark grey. The sharp "white -> black" transition gives off the illusion that the image is more detailed than it really is. In fact, since it is generally a type of convolution filter, you are actually destroying data. Overdo it and you get a noisy mess.

Thats exactly right, except at least you don't get people walking around saying the sharpen filter "shows you reality like it really is" or "elevates your state of consciousness."

Anecdotally, they do something.

I'm terrible at basketball, totally shit, can't sink a fucking thing.

Walking around on shrooms one night (so not a collosal dose), and I somehow ended up messing around on a court.

Somehow I was sinking ~3/4 of the shots that I took.

Do note that throwing a basketball is not a purely, or even mainly, perceptual task. But I'm amazed you were able to do that. My coordination gets shot to shit when I'm on psychs.

It was weird.

The dudes invited me back, but I have no idea when or where I was.

I think it operates more on the attention mechanism, as well as exploring different (and often unbeknownst) search space in the processing (the long-term effect of which can be biological in ways we don't understand).

And if taken regularly and had a certain training for a prolong peroid of time, they should be able to "increase the quality" of perception the same way when you play tennis regularly and with enough time you will develop the motor skills and can finally "feel" and effortlessly hit the ball at the center of the racket while swinging your hand in a way the racket travels straight.

Or the same way one becomes less tone-deaf or more sensitive to sounds, etc, (of course, it may go the other direction too - but I think the computational cost is quite different (acquiring vs losing) - still, it's definitely possible, eg, for one to 'unlearn' their mother tongue, etc).

Of course everyone's different, but to me "hallucinate" is a bit too strong of an expectation anyways. Or perhaps "hallucinate" is technically accurate, but I've found that uninitiated people expect to have crazy full immersive seeing-things-that-aren't-there experiences on psilocybin (like how DMT trips are described) but almost everyone I've talked with about this stuff has "visuals" and certainly interesting mental imaginings, but not full-fledged hallucinations.

Like shifting patterns of colours and light that overlay your regular vision? Sure. Morphing patterns in things that are actually there like plants or carpets, like your brain can't "keep it straight" for more than a millisecond? Yup. Ability to "travel" in your minds eye into past memories? Totally. Feelings of union with God/Source/Divine/Other/Higher_Reality? You bet.

But not like full-fledged high-fidelity sights and sounds that one would mistake for reality as you normally perceive it, like a man standing there or a crazy monster appearing right in front of you.

Interestingly, it appears different strains of mushrooms produce different amounts or types of visuals too, and I'm sure there are hundreds of other variables also at play (captured in 'set and setting').

Thank goodness this stuff is being studied properly again.

> but almost everyone I've talked with about this stuff has "visuals" and certainly interesting mental imaginings, but not full-fledged hallucinations.

so, many years ago my roommate asked me to get some acid for him and his girlfriend for the fourth of July, I did, it was pretty good stuff. We spent some time sitting in his truck giggling and then we went to watch fireworks.

We got done and they seemed somewhat underwhelmed by the experience, I admit I didn't think it was that great although as a general rule I hate fireworks this was one time I thought it was nice. But he was having a fun time talking shit "oh, perhaps it's like this for everyone, some funny lights and laughing, but for Bryan it fryyyyssss him!" This was while we were walking away from the fireworks which was at the University of Utah, we came around a corner where you could see every car on the street with their lights on and the police cars with theirs sirens and people running around setting off their own little fireworks and it was just a hilarious moment of going from little sensory input to incredible overload and the two of them couldn't handle it.

We drove back to our place and they were both freaking out and they thought they were going insane and would it be like this forever, I had to go out to get away from the general bad vibes.

Anyway not real hallucinations (although I did have a jalapeno open its mouth like it wanted to eat me one time which put me off eating it) but your post just reminded me of my ex-roommate and the chipper attitude before rounding that fateful campus corner.

A technique to see full-fledged hallucinations is to stare at one point for while, without moving your eyes. While you are staring at one point, focus your mind (in the right way that you just need to figure out yourself), on the thing you want to see, for example focus on Super Mario and you should be able to see Super Mario appear in front of you.

https://psychonautwiki.org/wiki/Main_Page

The hallucinative effects are well study. Here's a great common example: https://psychonautwiki.org/wiki/Scenery_slicing

The amount of psilocybin and type of strand have a strong influence on how drastic the effects are and what the effects are.

Magic Mushrooms can absolutely be DMT like and users can have full blown life like hallucinations of entities or landscapes. Most people simply dont do enough and have a light experience. DMT is simply less forgiving in this regard.

> I would never try them again though. Too risky. I value my mental health too much.

I know what you're trying to convey but I don't think this is the right way to say it. I akin Psilocybin to a microscope. Following the same analogy, if the microscope gets too close to the specimen it might kill it. But no one would ever suggest that not using a microscope to diagnose, let's say bacteria, would be to the benefit of "valuing your health". Rather, these should be conducted with trained practitioners (e.g. someone who knows how to properly use a microscope).

If you take 0.5-1g of mushrooms you will probably only get high as you note. The tripping starts when you are taking closer to 2g.

A veteran of the late 60's and early 70's here. Psilocybin was indeed my favorite recreational drug. No waking up with an acid hangover and feeling like your dog had died. No fear and loathing. The most complex and beautiful baroque music I ever heard was on unplugged headphones with psilocybin directing the phantom orchestra...

The nuggets (imho):

> psychedelic drugs activate the 5-HT2A serotonin receptor. Once stimulated, these receptors make neurons more excitable, and their blanket activation by psychedelics causes widespread changes to neural networks.

> There are 5-HT2A receptors throughout the brain, but they are most abundant in the cerebral cortex, particularly in areas responsible for cognition and self-awareness. Furthermore, 5-HT2A receptors are highly expressed in the visual cortex, and on the ends of axons that cortical neurons send elsewhere in the brain, such as the thalamus, where sensory information is processed.

> these studies indicate that psychedelics lead to “more connections between networks, and less connectivity within networks,” ... brain areas that usually have strong functional connections — and that operate in a network that has a fairly circumscribed function — become less connected, suggesting that the drugs disrupt those networks’ normal outputs. And brain areas whose activity is normally only weakly correlated become more connected.

It turns out that the majority of the 5-HT receptors (and 5-HT itself) are found in the gastrointestinal tract, not in the brain. https://www.sciencedirect.com/science/article/pii/0163725894... https://pubs.acs.org/doi/10.1021/acschemneuro.6b00414

Maybe that is why bowel movements are fairly common during the come-up of a trip.

Definitely. Your guts are tripping out too.

> These studies have revealed that psychedelics cause brain regions whose activity is normally robustly coupled to become less coordinated. And many regions that are usually only loosely connected start to communicate with each other more

The same effects are seen with deep meditation, which is interesting because LSD may offer a faster path to neuroplasticity [0] and potentially some of the other meditation related benefits (stronger DNM/sense of self).

[0] "a single administration of a psychedelic produces rapid changes in plasticity mechanisms on a molecular, neuronal, synaptic, and dendritic level" -(https://www.frontiersin.org/articles/10.3389/fpsyt.2021.7246...)

>The same effects are seen with deep meditation,

The same type of effects can be achieved with meditation, but to a much, much, much lesser degree.

Can you support that? I'm sure it depends on the doses, and this makes me wonder how the risks compare as well

Interesting stuff.

Is there anything that backs up the assumption below? It seems to make sense, but I'm wondering if it's possible the change in activity with the drug(s) could also mean that the areas are operating independently (on separate tasks switching so quickly to be essentially parrallel, or operating on an unconscious task).

"... to look for correlations in blood flow between two or more regions. When correlations are found, the assumption is that these brain regions are communicating and are engaged in the same cognitive processes ..."

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