Abstract
A single dose of psilocybin, a psychedelic that acutely causes distortions of space–time perception and ego dissolution, produces rapid and persistent therapeutic effects in human clinical trials1,2,3,4. In animal models, psilocybin induces neuroplasticity in cortex and hippocampus5,6,7,8. It remains unclear how human brain network changes relate to subjective and lasting effects of psychedelics. Here we tracked individual-specific brain changes with longitudinal precision functional mapping (roughly 18 magnetic resonance imaging visits per participant). Healthy adults were tracked before, during and for 3 weeks after high-dose psilocybin (25 mg) and methylphenidate (40 mg), and brought back for an additional psilocybin dose 6–12 months later. Psilocybin massively disrupted functional connectivity (FC) in cortex and subcortex, acutely causing more than threefold greater change than methylphenidate. These FC changes were driven by brain desynchronization across spatial scales (areal, global), which dissolved network distinctions by reducing correlations within and anticorrelations between networks. Psilocybin-driven FC changes were strongest in the default mode network, which is connected to the anterior hippocampus and is thought to create our sense of space, time and self. Individual differences in FC changes were strongly linked to the subjective psychedelic experience. Performing a perceptual task reduced psilocybin-driven FC changes. Psilocybin caused persistent decrease in FC between the anterior hippocampus and default mode network, lasting for weeks. Persistent reduction of hippocampal-default mode network connectivity may represent a neuroanatomical and mechanistic correlate of the proplasticity and therapeutic effects of psychedelics.
It is my understanding that the Buddha and/or the Buddhist tradition was and always has been well aware of psilocybin and probably other psychedelics and herbal drugs, like opium and cannabis.
In light of this, it is significant that the Fifth Precept for lay Buddhists proscribes only alcohol, and it does this very specifically by mentioning two types of alcoholic beverages (fermented and distilled) and nothing else. The Fifth Precept does not mention any other drugs.
As modern Buddhists, we can see that this conforms with what many of us have experienced with psychedelics and cannabis, among other ‘recreational’ drugs. Of course those drugs can be harmful but they can also do people a lot of good. Alcohol use, on the other hand, too often leads to very dangerous and spiritually stultifying mental conditions that do no one any good.
I have no problem with Buddhist teachers extrapolating the meaning of the Fifth Precept to include other drugs and sensory indulgences, but also believe that paying attention to the original meaning and its socio-environmental context (when people knew lots about plants) is important to keep in mind.
For more on this see: Are We Misunderstanding the Fifth Precept? ABN
American Buddhist Net 