LSD was a relative latecomer to long-established traditions of humans consuming hallucinogenic substances. But in a linguistic sense, it was the first psychedelic. In 1956, British psychiatrist Humphry Osmond coined the term “psychedelic” to describe LSD’s intoxicating effects in correspondence with writer Aldous Huxley.
Those who ingest the drug can experience kaleidoscopic visual patterns, a temporary dissolution of self, a slowing or stopping of time, and wild shifts in mood that can range from deep euphoria to severe anxiety and confusion. Read more: “This Obscure 1960s Guide to LSD Holds Up” Since at least 2012, scientists have believed that LSD and other psychedelics such as psilocybin alter experience by turning the dial down on activity in the brain’s specific control centers, such as the default mode network, which serves as a central conductor, regulating self-reflection and autobiographical memory and maintaining a sense of ego, or self. More recent research has complicated this idea somewhat, suggesting that connections between some networks are actually strengthened by psychedelics.
But now a small study published earlier this month proposes that LSD may also speed up some key brain rhythms and make brain activity more fractal, with certain patterns emerging and repeating across different timescales. Rather than quieting activity in certain control regions, the drug may also simply alter the background hum. In other words, it’s less that LSD turns off the brain’s controller than that it reshuffles how the whole system talks to itself.
The team published their results in Communications Biology. In the same way, overlooking the shift to faster brain rhythms can lead us to misinterpret LSD’s effects on the brain.” The study was co-authored by Jerbi, together with his doctoral student Venkatesh Subramani and others. Jerbi and his colleagues re-analyzed the brain recordings of 17 volunteers who either got LSD or a placebo saltwater injection on two separate days.
To analyze the subjects’ brain rhythms, the researchers used a technique called magnetoencephalography (MEG), which picks up tiny magnetic fields the brain gives off and can measure changes in that activity over a matter of milliseconds. The volunteers lay quietly with their eyes closed, sometimes in silence and sometimes while listening to one of two seven-minute excerpts from the electro-acoustic ambient album Yearning by Robert Rich and Lisa Moskow. The team found that LSD sped up the two main rhythms in the brain, known as alpha, which dominates when we’re at rest, and beta, which is linked to focus and decision-making.
Using MEG, the researchers found that, in fact, alpha waves sped up by about 2 beats per second, and beta by about 5 beats per second, across large swaths of the cerebral cortex. Older studies had not picked up this change in rhythm because of the way they measured brain activity. The old method measured only strength: how much total power fell within a specific pre-determined band of frequencies that typically correspond with each type of wave.
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