A Dominant Frontoparietal Beta State After Psychedelic Use

Chloe West, Bradley Baker, Jordan Hamm and colleagues from the University of Alabama, Georgia State University, NYU, and collaborating institutions

This study looks specifically at the period after a psychedelic experience rather than the acute drug state itself.

The researchers recorded resting EEG from people who had recently used either psilocybin or LSD, people who had recently used 5-MeO-DMT, and a control group. They used dynamic functional connectivity, which treats the resting brain as moving between recurring patterns of communication rather than assuming connectivity remains constant throughout the recording.

They found that people who had recently used psychedelics spent more time in a particular beta frequency state involving synchronized activity across frontal and parietal regions. They also remained in that state for longer periods when it appeared. The effect was smaller in people measured further from their most recent psychedelic use and approached the level seen in controls by about three weeks. This comparison was across people, not repeated measurements showing recovery within the same individuals.

The researchers also measured neural entropy. Increased entropy, or signal complexity, is one of the better-known findings during the acute psychedelic state. They did not find that same elevation in the people they studied after the acute experience had ended.

The brain after a psychedelic does not necessarily look like a weaker version of the acute psychedelic state. The acute increase in complexity may be gone while particular patterns of network organization remain altered.

The authors discuss these results in terms of continuing changes in top-down and bottom-up information processing after the acute state. Beta activity is commonly associated with top-down signaling, while other frequency ranges are more involved in carrying information upward through the cortical hierarchy.

This overlaps closely with Neural Attunement because my interest is not simply whether there is a period of increased plasticity after treatment. I want to know what the nervous system is doing during that period and whether the pattern of recovery tells us anything about outcome.

One possible future direction would be to follow the same individuals from before treatment through several post acute time points, extending these findings with longitudinal measurements. Ideally, I would want baseline data, early post-acute measurements, and follow-up at several time points: several days, one week, two weeks, one month, and later. I would also pair resting EEG with a battery of testing.

This could help address another question: does the way the nervous system reorganizes after treatment predict who improves, how they improve, and whether that improvement lasts?

The version discussed here is a preprint that has not been certified by peer review. The sample included 14 recent psilocybin or LSD users, 12 recent 5 MeO DMT users, and 16 controls.