People with schizophrenia experience significant disturbances in the minimal self, particularly in the sense of body ownership and sense of agency. A meta-analysis of 25 studies (690 patients, 979 controls) found a moderate overall effect (Hedge's g = 0.51) indicating basic self-disturbance. Body ownership showed a large effect (0.91), agency a moderate effect (0.49), and self-reported subjective experiences a moderate effect (0.57). The disturbed sense of agency suggests exaggerated self-consciousness rather than a diminished sense of self. Results remained significant after correcting for publication bias.
Psilocybin, a hallucinogen that mimics psychotic symptoms, alters brain connectivity in ways similar to psychosis. In a double-blind placebo-controlled trial with 20 healthy subjects, standard coherence analysis showed decreased connectivity in theta, alpha, and beta brainwave bands, particularly in frontotemporal and frontoparietal regions, along with frontal interhemispheric disconnection. Changes in higher frequencies were less significant and often opposite. In contrast, eLORETA connectivity analysis found no changes in lower frequencies but increased connectivity in high gamma (50-100 Hz). These preliminary results suggest psilocybin-induced connectivity changes align with those seen in psychotic patients.