Updated: Aug 22, 2018
By Nick Grubinger
Entheogens, more commonly referred to as psychedelics, are referenced in many cultures. When Albert Hofmann experienced LSD in 1943, entheogens had been in use by spiritualistic cultures for thousands of years. Today, references to entheogens constantly crop up in pop culture: an entire album entitled Acid Rap by Chance, L$D by A$AP Rocky, a documentary called DMT: The Spirit Molecule, not to mention most of psychedelic rock. How and why have these drugs intrigued the brains of so many? While a Shuar shaman and your average Dead Head probably have different answers to that question, entheogens have been subjected to scientific inquiry. This article shares how recent neuroscience literature contributes to our understanding of these mysterious drugs.
If Your Brain was an Orchestra, the DMN Would be the Conductor
One of the brain networks of interest in the LSD experience is the Default Mode Network (DMN). The DMN is a group of intercommunicating structures in the anterior and medial portions of the brain – think prefrontal cortex to hippocampus. These brain areas help direct attention to the correct stimuli based on a person's goals, and rely on communication with the other structures of the DMN. The DMN is often associated with a person's sense of self and theory of mind — theory of mind is your brain's method of analyzing the internal emotions and motives of other people. In sum, if your brain was an orchestra, Letheby (2017) says, the DMN would be the conductor.
The Orchestra-Conductor Theory: Evidence from Three Studies
Recent research has suggested that entheogens (i.e. LSD, psilocybin, and ayahuasca / DMT) are associated with a decrease in DMN activity which is paired with an increase in entropic activity, a type of brain activity that is particularly random or hard to predict. It is intuitive that reducing the role of the brain's "conductor" (the DMN) is coupled with more disorderly behavior of the "orchestra" (the rest of the brain), since the conductor is key in helping the orchestra work in unison.
More evidence supporting the orchestra-conductor theory is provided by Soler et al. (2016) who found the posterior cingulate cortex (PCC), a key structure of the DMN, was thinner in subjects who had a history of ayahuasca use. These findings accord with another study by Carhart-Harris et al. (2012) which established that subjects who ingested psilocybin and subjectively described the experience with the term "ego dissolution" also showed decreases in alpha waves coming from the PCC.
Two years later, research by Carhart-Harris et al. (2014) argued that quieting the DMN is key for dissolving the ego and creating a state of entropy in the brain. These changes help subjects break out of their habitual neural pathways and allow subjects to create and strengthen new or underused neural pathways. This model could be used to explain the therapeutic effects of entheogens, and is supported by research finding the degree of brain entropy during controlled LSD trips predicted the "openness to experience" personality trait two weeks later.
Figure 1 - Brain areas that emit different types of waves during ego dissolution experiences.
Taken together, this neuroscience research suggests that taking some psychedelic drugs inhibit brain areas responsible for identifying goals, directing focus, and self image. Perhaps it's not so strange, then, that spunions and healers alike discuss a feeling of unity.
Carhart-Harris, R. L., Erritzoe, D., Williams, T., Stone, J. M., Reed, L. J., Colasanti, A., ... & Hobden, P. (2012). Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin. Proceedings of the National Academy of Sciences, 109(6), 2138-2143.
Carhart-Harris, R. L., Leech, R., Hellyer, P. J., Shanahan, M., Feilding, A., Tagliazucchi, E., ... & Nutt, D. (2014). The entropic brain: a theory of conscious states informed by neuroimaging research with psychedelic drugs. Frontiers in Human Neuroscience, 8.
Lebedev, A. V., Kaelen, M., Lövdén, M., Nilsson, J., Feilding, A., Nutt, D. J., & Carhart‐Harris, R. L. (2016). LSD‐induced entropic brain activity predicts subsequent personality change. Human brain mapping, 37(9), 3203-3213.
Letheby, C. (2017). Naturalizing psychedelic spirituality. Zygon®, 52(3), 623-642.
Soler, J., Elices, M., Franquesa, A., Barker, S., Friedlander, P., Feilding, A., ... & Riba, J. (2016). Exploring the therapeutic potential of Ayahuasca: acute intake increases mindfulness-related capacities. Psychopharmacology, 233(5), 823-829.