A single high dose of psilocybin (25 mg) massively disrupts functional connectivity in the human brain, causing more than threefold greater change than methylphenidate (40 mg). These changes are driven by desynchronization across spatial scales, dissolving network distinctions by reducing correlations within and anticorrelations between networks. The strongest effects occur in the default mode network, which is connected to the anterior hippocampus and is thought to create the sense of space, time, and self. Individual differences in connectivity changes are strongly linked to the subjective psychedelic experience. A persistent decrease in connectivity between the anterior hippocampus and default mode network lasts for weeks, suggesting a neuroanatomical correlate of the therapeutic and proplasticity effects of psychedelics.
A narrative review of 30 studies examined how exercise, mindful movement, and mindfulness training affect resting state functional connectivity (rsFC) in the brains of non-clinical adults. Most studies reported changes in rsFC within the default mode, executive control, and salience networks. However, the largest and most methodologically rigorous study found minimal associations between rsFC and either exercise or mindfulness. Given the inconsistent results, caution is warranted in interpreting changes in rsFC attributable to these interventions. Methodological consistency in fMRI acquisition, data preparation, and analytical approaches is crucial to improve reproducibility and allow for comparison and aggregation.