Psychedelic Medicine


How Psychedelics Affect the Brain with Manesh Girn, PhD(c)


In this episode of the Psychedelic Medicine Podcast, PhD candidate and psychedelic science YouTuber Manesh Girn discusses his recent research on psychedelic brain action. Manesh is in the final stages of obtaining his PhD in neuroscience at McGill University and is an author on over a dozen peer-reviewed articles on psychedelics and related topics. He is also chief research officer at EntheoTech Bioscience and runs the YouTube channel the Psychedelic Scientist.

In this conversation, Manesh discusses his recent article in Trends in Cognitive Sciences titled “A complex systems perspective on psychedelic brain action.” He explains the complexity science approach used in the article, which emphasizes the brain is a holistic, interconnected system, rather than individual component networks that can be isolated. From this standpoint, Manesh critiques some simplistic explanations of the neural mechanisms of psychedelics which focus exclusively on interactions with the default mode network isolated from other brain systems.

He also explains how individual some of the neural effects of psychedelics are, citing different findings from different studies and observed variations between brain scans of different people. By better understanding these individual differences, and placing these different responses into a complexity science framework, Manesh believes that more individually-tailored psychedelic therapies are possible once the systems involved are more comprehensively understood.

Manesh closes this discussion by explaining the difference between genuine complexity and sheer chaos. Complexity, he explains, is a delicate balance of novelty and order, which is why psychedelic experiences can be both destabilizing and productive of novel insights and personal transformation.

In This Episode

• The research into psychedelics and the default mode network
• Using frameworks from complexity science in psychedelic research
• Measuring entropy in the brain
• Differences in neurological effects from taking between different studies and different individuals
• How a complexity science approach to neuroscience could better inform precision psychiatry


“You can’t just look at a specific brain region or network [in psychedelic research], you’ve gotta talk about the brain as a whole, in this sense of seeing the brain as a system of interacting parts.” [4:49]

“The core idea of this paper is that psychedelics put our brain into this state that is more dynamically flexible, it’s more diverse in its activity patterns, and it’s more sensitive to inputs that come in.” [14:17]

“What we find in the brain imaging findings is that different studies disagree, but also if you look at individual people, they can have radically different effects on their brain—almost opposite.” [21:37]


* The Psychedelic Medicine Podcast has allowed the Psychedelic Medicine Association to post episodes as an educational resource, and in return the PMA is hosting the podcast show notes.