A review of dynamic neuroimaging research suggests that the brain's spontaneous activity fluctuates in a non-trivial, structured way, compatible with exploring a discrete repertoire of states. This supports the hypothesis of a dynamic core—a constantly evolving but transiently stable set of coordinated neurons that forms the physical substrate for each conscious experience. Studies indicate that metastability in brain dynamics may underlie this repertoire and that it can be modified during altered states of consciousness. The review proposes that linking metastability to the level of consciousness could lead to a mechanistic understanding of altered states using dynamical systems theory and statistical physics.
Classic serotonergic psychedelics and dissociative drugs like ketamine produce overlapping subjective effects despite different pharmacological mechanisms. Using source-localized magnetoencephalography, researchers found that LSD, psilocybin, and ketamine all caused widespread broadband reductions in spectral power. Machine learning classifiers trained on one pair of drugs could identify the third, confirming similarity. Functional connectivity analysis revealed decreases in low alpha and theta bands specific to LSD and psilocybin, linked to 5-HT2A agonism, while low beta band decreases were common to all three drugs. These findings quantify shared large-scale brain activity patterns across drug classes and suggest that beta band decoupling is an effect shared between NMDA antagonists and 5-HT2A agonists.