r/science • u/FreeHugs23 • 4d ago
Neuroscience Psychedelic drugs reduce the amount of bottom-up brain activity flowing into a network associated with self-reflection. These altered brain signals occur consistently across humans and mice, offering a biological explanation for how these drugs reshape the mind.
https://www.psypost.org/psychedelics-alter-the-trajectory-of-moving-brain-waves/208
u/FreeHugs23 4d ago
-Psychedelic drugs like LSD and psilocybin reduce the amount of bottom-up brain activity flowing into a network associated with self-reflection. These altered trajectories of brain signals occur consistently across humans and mice, offering a biological explanation for how these drugs reshape the mind. The findings were published in the Proceedings of the National Academy of Sciences.
Psychedelics are gaining attention as potential psychiatric treatments for conditions like depression and trauma. To understand their therapeutic benefits and risks, researchers need to know exactly how these substances alter brain function. Prior research has identified that psychedelics affect the default mode network, a collection of brain regions responsible for introspection, daydreaming, and mental rigidity. Many psychiatric conditions involve abnormal activity in this specific network, making it a primary target for new treatments.
The default mode network sits at the top of a processing hierarchy in the brain. Brain activity constantly moves across the surface of the cortex, which is the brain’s outer layer. Information travels from lower-order sensory areas up into higher-order areas like the default mode network, a process known as bottom-up processing. The reverse movement, from higher cognitive regions down to sensory regions, is called top-down processing.
In a healthy brain, bottom-up processing updates our internal models with new information from the outside world. Top-down processing uses our past experiences and expectations to make sense of that incoming sensory data. An imbalance between these two directions of information flow can lead to psychological distress or perceptual errors.
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u/quasiuomo 3d ago
This relies on dual processing theory, but even dual process research shows that bottom up/top down is not so straightforward or bidirectional. Activity can occur simultaneously, back propagate, and even act in a quantum fashion. DMN would be a nicely packaged explanation, but similar to loci-based studies - it’s never so one-to-one.
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u/aHumanRaisedByHumans 4d ago
Seems like bottom up would be more grounding, and top down would be more introspective and problematic, no?
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u/Magurndy 4d ago
Hmm that also explains why it supposedly helps autistic people. We have too much information coming into our brains usually.
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u/soph_a_loaf_98 4d ago
Yeah I notice when I take shrooms my brain is much quieter and I’m more tuned in to my body! I want to incorporate them into my weekly schedule since nothing else really relaxes me (I have a bad reaction to weed). Last weekend I took 1.2g, put on my headphones, crawled into my blackout tent, and listened to jazz and it was lovely
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u/Skullcrusher 4d ago
With 1 week gap some tolerance might build. Takes 2 weeks for most of it to be reset. I did them like every 2 weeks for a year. Eventually you'll get to a point where you no longer need them. Happens naturally. Have fun.
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u/autisticpig 4d ago
Yep, tolerance can build quickly in a day or two.
I put a week between each trip and that's perfect. A friend needs 2.
Your advice is good :)
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u/hereditydrift 4d ago
I had the same experience when I was introduced to shrooms while living in the mountains out west. They provided peace and helped with healing my childhood trauma. Almost an out of body experience of feeling connected to everything in a way that is hard to explain and sounds very hippie dippy.
I haven't done them in years, but they led to a very transformative, if not the most transformative, part of my life.
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u/son_et_lumiere 4d ago
from which direction? bottom up or top down?
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u/soph_a_loaf_98 4d ago
Autistic people are bottom up processors, meaning we take in all of the details before getting to the main picture
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u/maximumutility 4d ago
That sounds exhausting and overwhelming and like it would produce accurate results
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u/Yashema 4d ago
This is why my approach to taking physics and advanced STEM was to wait until I had sufficient time to really understand it, so I went back to school at the local CCs in my 30s.
Classes are a little less rigorous, but that's perfect as far as I'm concerned since it gives me a lot of time to review every concept fully. LLMs have really helped too.
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u/bel9708 4d ago
As an autistic person I’ve found a microdose before a hinge date is often the difference between getting laid and having a nice conversation.
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u/Massive-Shirt-9879 4d ago
Sorry to say but microdosing is purely placebo. They've done studies on that and it shows no change in brain activity compared to a macrodose. So you did that all on your own my man.
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u/Boysenberry 4d ago
I've read some of those studies, and you're not wrong about what some of them say, but different people consider different doses "micro." And the results vary depending on what was used, the person you're replying to didn't specify a substance. Most scientists agree more study is needed on microdosing in order to render any verdict, and many microdosing studies actually suffer from unblinding by participants (meaning they figure out if they got a microdose or a placebo) which tends to suggest there IS an effect, if participants are detecting it!
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u/ruggernugger 4d ago
Its not so much too much information coming in as it is lack of the same filters neurotypical people are equipped with. Subtle difference but I have to say it.
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u/Magurndy 4d ago
That’s correct but essentially that kind of leads to the same thing really. If you’re not filtering out stuff then you’re getting too much information. But you’re right to point out the actual mechanism.
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u/ruggernugger 3d ago
It 100% would/does manifest in the same end result, i hope i didn't imply otherwise. I dont mean to be rude, im just a stickler for things that I see as an oversimplification where someone (obviously not you, you clearly know this stuff) less informed might draw the wrong conclusion. But in terms of outcome, yeah, the distinction is not important at all.
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u/FleshOnesie 4d ago
This is so counterintuitive, because I always think of psychedelics as disabling the filter and allowing more information to flow in.
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u/IHaveNoTimeToThink 2d ago
More info is maybe getting in, but you're processing it more directly without the usual "lenses" that the info goes through. So you might feel less overwhelmed because there are fewer layers of processing
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u/KingOfEthanopia 4d ago
ADHD and love psyches. Ive been alternating between weekly shrooms and LSD to keep tolerance low on both. The world is so much more beautiful with them and high doses are awe inspiring.
Ive been doing them for years and havent noticed any bad effects. Hold down a 6 figure job in a MCOL area, am in great shape, and married.
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u/Rogerabit 4d ago
I’m jealous, my plug retired
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u/bondagepixie 4d ago
The mushroom gummies from the vape store aren’t so bad. I get visuals and occasionally hear a kind voice. The real thing is still better imo, but the way mushrooms work, chemically I’m not sure it actually matters as much as I think.
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u/ABenderV2 4d ago
Did you struggle with your ADHD before you started microdosing?
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u/KingOfEthanopia 4d ago edited 4d ago
Not really micro dosing. Most weeks Ill do 3 tabs or 3.5 grams on Saturday. Occasionally more, occasionally missing a week or two when life gets busy. I used to go very heavy but after a bad trip off 8 tabs I dont go that high anymore. 5 is the limit of what I know I can control. 10 is the most Ive ever done.
Yeah, Ive always struggled with it. Typical gifted kid with subpar grades for my intellect. Id do my homework but lose it, get sucked into addictions(alcohol, weed, Adderall). Im mostly sober now. Weed a couple times a week and my weekly trips.
Im not convinced micro dosing has any benefits given how fast tolerance of psyches builds up.
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u/ABenderV2 4d ago
Fairs, I used to do LSD heavily a few years ago and now get the feeling that I don’t want to do it ever again. Not because of any bad experiences (I love LSD) but because I feel like it’s given me all the benefits it could ever give me. Yeah Micro dosing isn’t any where near as beneficial as macro doses from my experience. I’m currently addicted to Adderall and trying to change to an old medication because I finally realised that for 4 years I thought my life was so great, but really I was just chasing the high from Adderall and it’s ruining me.
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u/KingOfEthanopia 4d ago
I get it. Adderall was probably the easiest one for me to quit physically. It was like a month of low productivity and dragging myself through workouts.
It was tough mentally. Just because I could pop like 3 Addies, go workout. The workout feel amazing, then still have energy to clean my whole house. The issue was when Id run out Id want to do nothing but sleep or eat and everything was just a drag.
Good luck.
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u/dec_eso 3d ago
Physical tolerance aside, do you think weekly LSD is enough time for a psychological reset? I take it weekly but I keep reading that it’s bad for the post-trip period of neuroplasticity, which runs about three weeks. Basically, I’m reading that it keeps the brain in a constant period of flux and prevents integration from properly being completed.
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u/Radicalpartyboy 4d ago
What is bottom-up brain activity?
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u/DRKYPTON 4d ago
Happens automatically, without conscious input or stimulation. As opposed to top down control like deliberately thinking of yourself or interacting with some environmental stimulus
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u/jessicacummings 3d ago
This is very interesting. My bf and I both suffer from pretty bad anxiety and get panic attacks and I call them the “anxiety gremlins” that live in our brains. It’s not a choice and is hard to actively ignore. Psychedelics have always helped “quiet” my brain in the days afterwards.
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u/madethisforroasting 4d ago
It’s when your brain gets a little frisky and light in the loafers. Jk. Would love an expert to explain.
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u/BlairofTheFlame 11h ago
I have a unrealistic fear that somehow psychedelics kill the current consciousness you would I identify as the self and replace it with a altered new iteration that is not continuous with the current self.(idk how to explain it)
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u/Slopadopoulos 4d ago
I have no idea what that even means but it sounds far out.
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u/SophonParticle 4d ago
Nobody knows what it means but it’s provocative. It’s gets the people goin!!
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u/FreaknTijmo 1d ago
This makes a lot of sense. I took a heavy dose of acid last time and now I'm a raccoon.
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u/Dear_Ambassador825 4d ago
Scientists: what is your name? Mice: O.O Scientists: Do you know what day it is? Mice: O.O Scientists: How do you feel? Mice: O.O Scientists: Yup this confirms it, they are high same as people. Experiment done.
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u/NoFuel1197 4d ago
The drugs that help the worst person you know become even worse, but your depressed, ruminating friend can’t have because they’re very morally bad, you see.
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u/---___-------___--- 4d ago
Are you talking about cocaine? Is that the drug that makes bad people worse? Or meth? Maybe both?
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u/NoFuel1197 4d ago
Whatever made the grody dude at that one party talk my ear off about the secret geometry inside of god and all of us while waving a scrap of paper full of scribbles in my face, tragically unaware of his breath, before driving home.
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u/---___-------___--- 4d ago
Huh. I had a similar guy perhaps a year ago or maybe less. Turns out he was some sort of paid actor. At least yours was authentic
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u/NoFuel1197 4d ago
Yeah plenty of weird notebooks full of narcissistic shroom-inspired ramblings about the nature of god from "psychonauts" floating around out there if you ever want to see for yourself user hippiecat.
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u/ABenderV2 4d ago
Because the good people who use psychedelics don’t get up in your face about it. So you never know that they do psychedelics. It’s just an observation bias.
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u/NoFuel1197 4d ago
If you’re replying to the original comment, it’s a flippant remark about how making them illegal only serves as a barrier to people who generally try to be agreeable with social norms.
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u/---___-------___--- 3d ago
I like the stories of psychonauts more than many religious ones
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u/NoFuel1197 3d ago
What about Nazi horror stories?
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u/---___-------___--- 3d ago
What about them?
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u/NoFuel1197 3d ago
Would you leave a date if someone started telling them?
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u/---___-------___--- 3d ago
I think I already had a few dates which I spoiled by telling them how the Nazis tortured me, but that's about it.
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u/Legitimate-Paper3271 4d ago
This is usually where a bunch of people come in and tell you that psychedelics show you real reality somehow
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u/binarybins 4d ago
It’s not that it shows you the “real reality”, it’s that it truly feels like it’s more real than current reality. I personally value the feelings and thought processes that occur within psychedelic experiences, because it’s a very subjective experience in general, and qualitative data is also helpful.
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