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Add99
04-07-2009, 06:29 PM
Upon the consumption of certain mushrooms, mandalas become visible. With closed eyes, they are infinite and fractal. With open eyes, they are a shimmering overlay of surroundings.

I am aware of the religious/spiritual history of mandalas (intricate multicolored circular patterns) but I wonder why they would become spontaneously visible in a suggestive/meditative/drugged state. They are well known and cross cultural. Why/how does the mind generate such patterns? Is it a glimpse into the underlying structure of the universe as some believe (I think not). Is it the rod/cone structure of the eye? Is it the visual center of the brain generating its own imagery?

Squink
04-07-2009, 06:38 PM
Phosphenes (http://en.wikipedia.org/wiki/Phosphenes)


Entoptic phenomena in contemporary art (http://www.entopticart.com/)

for a really nice introduction see: Oster, G. 1970. Phosphenes. Scientific American:222(2):83-87

Add99
04-07-2009, 07:00 PM
Thanks. What about spirit animals/guides. Also a common shamanic experience. Does that have an explanation also? I am just wondering about delusions and hallucinations which multiple people all experience in a similar fashion.

And does the white light near death experience qualify as phosphene as well? (from a non religious perspective)

HorseloverFat
04-08-2009, 02:32 PM
Sounds like confirmation bias to me. Are these things truly universal? Where are the studies? How about people who dont register mandalas and spirit animals. How about the idea that expectations affect the trip? etc.

MikeS
04-08-2009, 04:20 PM
One of my good friends in graduate school ended up working with a professor who's very interested in this question. As I remember it, the basic idea is that there are clusters of neurons in the visual cortex that are specifically wired to respond to certain spatial patterns registering on the retina. For example, cluster A of neurons would respond to vertical stripes, cluster B would respond to horizontal stripes, and cluster C would correspond to pinwheels (or something along those lines.) The "output" of these neurons is then fed into other parts of your brain for interpretation. Certain hallucinogenic drugs could then alter the brain's biochemistry sufficiently to cause clusters A, B, and C to start firing on their own, without any external stimulus from the retina; this is what would cause hallucinations. Thus, the patterns we see during hallucinations tell us about how the visual cortex is "wired up".

This is all half-remembered stuff, of course, and I may be getting the details wrong; here's a lecture given by said friend's advisor (http://www.archive.org/details/redwood_center_2006_02_14_cowan), who knows more about it than I ever will. You might also want to look into form constants (http://en.wikipedia.org/wiki/Form_constant), a classification of mescaline-induced "mandala" shapes done by Heinrich Klüver in the '20s.

user_hostile
04-08-2009, 05:32 PM
Upon the consumption of certain mushrooms, mandalas become visible. With closed eyes, they are infinite and fractal. With open eyes, they are a shimmering overlay of surroundings.

I am aware of the religious/spiritual history of mandalas (intricate multicolored circular patterns) but I wonder why they would become spontaneously visible in a suggestive/meditative/drugged state. They are well known and cross cultural. Why/how does the mind generate such patterns? Is it a glimpse into the underlying structure of the universe as some believe (I think not). Is it the rod/cone structure of the eye? Is it the visual center of the brain generating its own imagery?

Is the following a mandalas? I get a migraine about every three to five years. No pain, just a scary 45 minute loss of vision on the bottom right third of my eyes, with pulsating fractal triangles. First time, I thought I had stroke in the visual cortex. Finally got a CAT scan because it was starting to happen every two to three weeks--it showed no problems.

The only thing the neurologist recommended was taking baby aspirin. "For the headaches?" I asked. "No, becaue your're over 40" :p

I've only had one in the last seven years so maybe the aspirin helps.

Santo Rugger
04-09-2009, 01:56 AM
Sounds like confirmation bias to me. Are these things truly universal? ...
The ancient Aztecs certainly thought so.

MikeS
04-09-2009, 03:06 PM
The friend I mentioned in my previous post also pointed me towards this blog post (http://preposterousuniverse.blogspot.com/2005/02/hallucinatory-neurophysics.html), which explains things pretty nicely as well.

cwthree
04-09-2009, 05:28 PM
Is the following a mandalas? I get a migraine about every three to five years. No pain, just a scary 45 minute loss of vision on the bottom right third of my eyes, with pulsating fractal triangles. First time, I thought I had stroke in the visual cortex. Finally got a CAT scan because it was starting to happen every two to three weeks--it showed no problems.

The only thing the neurologist recommended was taking baby aspirin. "For the headaches?" I asked. "No, becaue your're over 40" :p

I've only had one in the last seven years so maybe the aspirin helps.

IANAD. Your description sounds more like a migraine aura with scintillating scotoma (http://en.wikipedia.org/wiki/Scintillating_scotoma).

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