Hallucinatory Neurophysics [the mathematics of visual hallucinations and NDE's]

Preposterous Universe blog ^ | February 4, 2005 | Sean Carroll

[snarks_when_bored]

Friday, February 04, 2005

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Hallucinatory Neurophysics

Everyone knows what it's like to experience the hallucinations that accompany certain kinds of drug use (among other mind-altering contexts) -- if not from direct experience, at least from depictions in movies and literature. We've seen the colorful, swirling patterns, or the illusory tunnels stretching before us. It turns out that hallucinations are by no means random; there are certain recurrent patterns reported by people who experience them. These patterns were studied by Heinrich Kluever in the 1920's and 30's, and classified into four different structures: spirals, spokes, honeycombs, and cobwebs. Subsequent work has suggested more complicated hybrid forms, such as that portrayed here, but the basic types seem to be robust.

Here's the good part: the appearance of these particular hallucinations can be explained by physics!

[snip]

So, the next time you have a near-death experience, and see a tunnel stretching before you leading to a beckoning light, it's not Jesus calling you into the afterlife. It's just some characteristic jiggling of the neurons in your weakened brain. Which, to my mind, is much more interesting.

[snarks_when_bored]

University of Chicago physicist Sean Carroll reports that two students at UC have produced a mathematical model of the cerebral cortex which generates the basic patterns of visual hallucinations.

Interesting, to say the least.

[snarks_when_bored]

Ping

[PatrickHenry]

Creationism explained!

[snarks_when_bored]

Part of it, maybe. The work, if it proves out, seems really quite remarkable.

(Up early, eh?)

[endthematrix]

Dr Persinger wrote an article a few years ago, titled "On the Possibility of Directly Accessing Every Human Brain by Electromagnetic Induction of Fundamental Algorithms".

The abstract reads:
"Contemporary neuroscience suggests the existence of fundamental algorithms by which all sensory transduction is translated into an intrinsic, brain-specific code. Direct stimulation of these codes within the human temporal or limbic cortices by applied electromagnetic patterns may require energy levels which are within the range of both geomagnetic activity and contemporary communication networks. A process which is coupled to the narrow band of brain temperature could allow all normal human brains to be. affected by a subharmonic whose frequency range at about 10 Hz would only vary by 0. 1 Hz."

[snarks_when_bored]

Persinger's the investigator who uses a magnetic helmet to induce subjects to feel the presence of somebody else in the room with them (when there's nobody there), right?

[endthematrix]

Yeah. CREEEPY!

[endthematrix]

It was the central algorithm in the abstract that was the point of the posting.

[snarks_when_bored]

Ah, I see that now. I remembered Persinger from a T.V. piece on his work last year (or the year before), and also an article from a now-forgotten source.

[endthematrix]

Afterlife explained!

[wastoute]

Does Aluminum foil block this effect? Or does it have to be Tin foil. Can one still get Tin Foil? LOL.

[wastoute]

Would you imply that because there may be a natural explanation for a way to actually influence a mind without accessing it through the normal senses of sight, sound, etc. that we can now throw the Bible into the trash? If so, you have made quite a leap. One would almost say a leap of faith.

[snarks_when_bored]

"Step away from the helmet, ma'am, and nobody'll get hurt!"

[gobucks]

NDE ping...

[nuconvert]

pong

[AdmSmith]

the next time you have a near-death experience, and see a tunnel stretching before you leading to a beckoning light,

it is probably oxygen deprivation of the optical part of the brain (or the neurons in the eye). There is a similar effect when you switch off the electricity in an old TV set.

[Alamo-Girl]

Thank you so much for the ping!

It is an interesting article. Building up to the last paragraph, it speaks of "nonlocal features of the image, such as spatial or temporal frequencies in the brightness pattern, or the presence of correlated orientations within the image." All good and fine, the brain fills in the spatial/temporal geometry - which could indeed explain the 'vision' of a tunnel.

However, that last paragraph is not connected to the previous thoughts. He leaps to the conclusion:

So, the next time you have a near-death experience, and see a tunnel stretching before you leading to a beckoning light, it's not Jesus calling you into the afterlife. It's just some characteristic jiggling of the neurons in your weakened brain. Which, to my mind, is much more interesting.

The conclusion he wishes to draw does not follow from the evidence he presented.

IMHO, the most fascinating and candid of all the NDE accounts comes from the children who draw pictures of their experience soon after. There is precious little in their drawings concerning geometries though it appears quite frequently in adult recollections.

Here's an interesting article: Psychology Today: Bright lights, big mystery

[valkyrieanne]

Just because a blogger makes an unjustified remark, doesn't take away from the validity of the neuroscience. Some blind people can see these geometric forms directly in their brain (some without optic nerves, even.) These shapes have definite patterns and probably are the "source" of a lot of abstract artistic designs, like arabesques, a lot of tile and rug patterns, etc.

[Bobber58]

I'm no scientist, or researcher, but seems to me that if our brains can transmit radio-waves or whatever, that can be picked up outside the body, then we might be receiving too...which would explain why sometimes when people get prayed for, they get results...both the transmitter and receiver come into a sympathetic harmony...i.e. on the same frequency

[endthematrix]

Re: "Would you imply..."

No.