New Brain Images Show How LSD Affects Our Minds

Dropping acid lights up the brain's visual cortex and points at the brain regions involved in "altered consciousness."

The hippie movement didn’t do LSD any favors: Scientific research on the drug was put on indefinite hiatus after the psychedelic was co-opted by 1960s counterculture, even though it was originally developed by Albert Hofman as a psychological drug for treating psychiatric illnesses.

A new generation of LSD researchers, led by Robin Carhart-Harris, Ph.D., of Imperial College London, have taken up Hoffman’s torch and, by applying 21st-century brain imaging technology to the drug, took the science world’s first modern snapshots of LSD’s physiological effects on the human brain.

Visualizing blood flow in patients tripping on LSD revealed higher activity in the visual cortex, the part of the brain that deals with "seeing."

Carhart-Harris et al., PNAS

What they discovered could have major effects on the way we use psychedelics to model and treat psychiatric diseases. Half of the participants involved in Carhart-Harris’ latest study, published today in the Proceedings of the National Academy of Science, were given an IV drip of LSD and allowed take an “eye-closed, task-free, ‘resting-state’” trip before passing through an fMRI scanner, which visualizes the ebb and flow of blood in the brain, and an MEG scanner, which tracks the brain’s shifting electrical currents. Both techniques are meant to measure changes in overall activity, allowing the researchers to explore what LSD physically does to our brains.

It’s perhaps not surprising that the visual cortex — the part of the brain that processes what we “see” — came alive in participants that took LSD. There was a noticeable increase in blood flow as well as connectivity with other parts of the brain in patients who were tripping; follow-up interviews with the patients showed that these changes in the visual cortex were associated with strong visual hallucinations. The results echo the findings of a 2012 study on ayahuasca hallucinations, which found that the visual cortex acted as if it were “seeing” things, even though participants’ eyes were shut.

Taking LSD reduced the connections between the parahippocampus and the retrosplenial cortex, two regions thought to be associated with consciousness.

In the follow-up interviews, the participants also described being in a state of “altered consciousness” — namely, a “disintegrated sense of self” — a phenomenon that also had a compelling physiological parallel: The connections between the parahippocampus and the retrosplenial cortex were noticeably decreased, suggesting that this particular brain circuit was involved in how we think about the “self” or the “ego.”

Rather than using LSD itself as a psychological drug — there are certainly other scientists working on that — Carhart-Harris and his team used it as a probe for understanding what they refer to as the “neurobiology of consciousness.”

They’re hoping that their work could pave the way for using psychedelics not only to treat psychiatric diseases but also to model future studies on them. Demonstrating that there’s an actual physical basis to the psychological effects of LSD will, no doubt, boost psychedelics’ cred within the science community, which is still Leary leery of the formerly-fringe field.

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