Philosophical Speculations

LSD dose-dependently reduced oscillatory power across delta, theta, alpha, beta, and gamma frequency bands during both eyes closed and eyes open resting conditions. During the oddball task, LSD dose-dependently reduced ERP amplitudes for P300 and N170 components and increased P100 latency. LSD also produced dose-related increases in positive mood, elation, energy, and anxiety and increased heart rate and blood pressure

https://pubmed.ncbi.nlm.nih.gov/34613430/

But, but, but, experiences are generated by the brain! You hate science, you woo-woo quack!

Interesting study. There was an article about another study about LSD recently: https://bigthink.com/mind-brain/lsd-hal ... BQsF2fCWtQ

For the paper, see here: https://www.cell.com/cell-reports/fullt ... Dtrue#bib2

"One key finding was that the tripping rats showed decreased communication between the hippocampus and visual cortex. In the sober brain, these two regions collaborate to create spatial representations of the external world. But on LSD, the hippocampus seems to conjure images of reality without help from the visual cortex."

The study above, mentioned by 5MeO-DMT_Philosopher, is with microdosis of LSD; I wounder if it's also the case with macrodosis of LSD; (reductions of broadband oscillatory power (even gamma).

MaartenV wrote: ↑Wed Oct 27, 2021 10:40 pm The study above, mentioned by 5MeO-DMT_Philosopher, is with microdosis of LSD; I wounder if it's also the case with macrodosis of LSD; (reductions of broadband oscillatory power (even gamma).

I think that has been the observation with psychedelics in general. I was somewhat surprised it would have effect at micro doses.

In regard to the rats, I think a number of years ago a study of people on ayahuasca showed that the visual hallucinations were activating the same neural circuits in the brain that actual vision activated. That seems slightly different from this result. However, these are different drugs and, despite general similarities of effect, we probably shouldn't be surprised there are also differences.

In simple terms, I think vision (or any other conscious experience) is dependent upon synchronized firings of neurons. Many psychedelics have chemical similarities either to dopamine or serotonin so they have affinity for the same neurons that use those neurotransmitters. However, when the psychedelic reaches the neuron it doesn't work in exactly the same way as the expected neurotransmitter; hence, the precise symphony of firings becomes slightly dissonant, like the flutes come in too late or on a different timing than the violins.