Why Drugs Cause Hallucinations

Have you ever wondered why drugs cause people to hallucinate ? What are the biological reasoning behind such phenomena ? Some time back I had a lot of fun writing about how to get high and have hallucinations without the use of drugs. Since then a number of people have asked me if I am into hallucinations then how about a post on drugs that get one tripping out ? I have no problem with that, however I don't want this blog to get too far off the musical path which should be it's main focus. And beside there are thousands of blogs and forums that deal with exactly that topic and in far more detail then I could ever hope to achieve. 

However, what I thought might be interesting to share is some information on how such drugs cause hallucination in the first place - a topic that has always fascinated me. 

It's one thing to get high and enjoy what you see and or feel but I have always been far more interested in the bigger question of why the hell do I see what I see and why is it somewhat universally consistent in theme and characters ? 

If one takes a hit of LSD or ingests some magic mushrooms, then why do they always see such vivid geometric, spiraling, intricate lattice work or the same little machine elf like creatures ?


To begin with let's look at an interesting article in Neuron journal from back in February of 2007 in which experiments were detailed that involved giving LSD to rats to compare how the brain's 5-HT2A re­cep­tor molecules reacted as opposed to activating them with non hallucinogenic chemicals. The findings in the journal were summarized over at World Science website :

The re­search­ers found that LSD pro­duced an ar­ray of elec­tri­cal and cell sig­nal­ing re­sponses in the cor­tex very dif­fer­ent from those in­duced by the non­ hal­lu­ci­nogen.

When the mind-bending drug ac­ti­vat­ed the re­cep­tor, it not on­ly trig­gered the typ­i­cal changes in the cell, it caused ad­di­tion­al cell re­s­pon­ses, he said. The ev­i­dence for this, the group re­ported, was that the LSD seemed to cause a char­ac­ter­is­tic chain re­ac­tion of brain chem­is­try in­volv­ing a class of mo­le­cules called G pro­teins, which are of­ten in­volved in nor­mal sig­nal­ing pro­cesses.

The sig­nif­i­cance of the dif­fer­ence is un­known. But it was par­tic­u­larly no­tice­able in a spe­cial lay­er of cells in the cor­tex, called Lay­er 5, Seal­fon said. This is often de­s­cribed as the “out­put” lay­er of the cor­tex: it es­sen­tial­ly gath­ers up de­ci­sions made in that struc­t­ure and re­lays them on to oth­er brain re­gions, in­clud­ing cen­ters that ex­e­cute phys­i­cal move­ments.

Lay­er 5 al­so has ex­ten­sive in­ter­con­nec­tions to oth­er parts of the cor­tex, Seal­fon said. It’s al­so hy­poth­e­sized to con­trib­ute to a cer­tain fil­ter­ing func­tion, in which it helps squelch un­im­por­tant infor­ma­tion so that this does­n’t overwhelm oth­er brain ar­eas that don’t need it. Hal­lu­cino­gens may thus dis­rupt this fil­ter­ing, Seal­fon spec­u­lat­ed. “You have a sen­so­ry overload, a less fil­tered ex­pe­ri­ence of your sen­so­ry in­put.”

What can we take from that exactly ? That LSD and hallucinogens turn off filters ? Hmmm, that reminds me of what people like Graham Hancock and Aldous Huxley talked about when they said that perhaps these drugs are more like tuning a radio - when we take hallucinogens they filter out everything to such a degree that we are left "tuned in" to another existence. 

Still this doesn't exactly answer the question of why do we see what we see ? Why , when we have this "unfiltering" do we see such "sacred geometry" ? For that we may need to get down and dirty with the filthy world of mathematics. While there hasn't been a lot of research done into the field of geometric hallucinations, what is there is quite thought provoking ( and somewhat headache inducing ). 

If you are interested in reading about the mathematics behind hallucinations then you can follow some of the links below, but for now I'll just try to summarize in simple terms what has been discovered so far. 

The study of mathematical geometry and it's role in hallucinations has been going on since the early 20th century. In the 1920s, psychologist Heinrich Klüver ingested some peyote cactus ( which includes the active hallucinogenic compound known as mescaline ) and took note of the different kind of repeating geometric hallucinations he saw. He classified the patterns into four distinct groups which he termed "form constants" - tunnels and funnels, spirals, lattices including honeycombs and triangles, and cobwebs. 



Some 50 years later, in the 1970s the mathematicians Jack Cowan and G. Bard Ermentrout used Klüver's classifications as a basis for further research where they formed a theory as to how our brain makes of believe we are seeing such patterns. 

In short they suggest that such patterns are the result of specific "noise patterns" in the visual cortex which are subsequently transformed by the wiring between the brain and the eye to produce these unique geometric forms. 

Their research has been expanded on over the past 40 years by a number of scientists including mathematical neuroscience professor Paul Bressloff. Bressloff is one of the leading mathematical thinkers in the world today and his ground breaking research into the mathematics behind brain chemistry is helping to evolve our overall understanding of what it is to be human. 

Bressloff, in collaboration with Cowan and a number of others, used their expanded research into the mathematics of the original 1970s research to discover that the mechanisms that enable all of us to detect edges, contours, surfaces and textures in the visual world generate the hallucinations. It is when these mechanism become unstable, for example due to the influence of a drug, that patterns of neural activity arise, which in turn translate to the visual hallucinations. 


I find all this quite exciting. I have long wondered why people all over the world should see the same psychedelic geometric patterns when under the influence of drugs, regardless of their age, race or upbringing. Why did cavemen paint similar images on cave walls ? This research highlights the fact the it's because we all share the same biology of the brain, the same visual cortex makeup, that we see similar patterns. 

So the next time someone tries to convince you that what you are seeing is a direct line of communication to the spirit world or some kind of WIFI connection to Gaia's hard-disk, then perhaps you might want to point out that it's all just a matter of biology and numbers. Of course some people will then argue why do I see little green elves or a purple sun 10 meters above my head, my own DNA riding a bicycle and singing the theme from Bewitched ? That, I must say, is a mystery. While I can accept that hallucinations of the geometric pattern type described by Bressloff above are caused by the makeup of the visual cortex in all of us I find it difficult to find answers as to why one hallucinates full scenes involving characters that take over our entire visual field and environment. This gets into the territory researched by people like Dr Rick Strassman in his book "DMT The Spirit Molecule" which I highly recommend. Rick doesn't provide any final answers but it's great to read that there are doctors giving the topic serious consideration.


Read more about the mathematics behind why drugs cause hallucinations here : 



Downloadable PDF files :




Posted on 23.1.13 by PsyAmb TAG : | 2 Comments ( ADD NEW COMMENT )

2 comments :

Anonymous said... @ 26 January, 2013

Recenbt research on Psiocybin in the Uk haad participants hooked up to MRI scanner - which showed decreased brain activity. What we may be talking about is the mind not the brain.
your explanation is a materialist one and does not ring truein my opinion

Anonymous said... @ 17 December, 2015

Your last statement which is "Your explanation is a materialist one and does not ring true in my opinion" proves you either didn't read the article or don't have the ability to comprehend anything. This post pulls directly from studies scientists conducted not some bullshit he pulled out of his ass.. such as your comment is. :)

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