A case series comparing pre and post-treatment with psilocybin was conducted in 19 patients with treatment-resistant depression. Patients were assessed on the the Quick Inventory of Depressive Symptomology-Self Report (QIDS-SR16) before and after treatment, and also underwent fMRI to examine resting-state functional connectivity. All participants showed decreased depressive symptoms at 1 week, with 47% reaching criteria for being responders at 5 weeks. Whole brain analysis showed decreased cerebral blood flow in the temporal cortex, including the amygdala, with decreased amygdala blood flow being correlated with reduced depressive symptoms. Resting state functional connectivity was predictive of response at 5-weeks, with increases in ventromedial prefrontal cortex-bilateral inferior lateral parietal cortex connectivity and decreases in parahippocampal-prefrontal cortex connectivity predicting a responder.