Department of Psychiatry and Neurosciences, Charité-Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany.
2 papers in the library · 11 citations · publishing 2025-2026
Perception normally balances external sensory signals with internal predictions based on prior knowledge. In a double-blind, placebo-controlled, cross-over experiment with healthy participants, the N-methyl-D-aspartate receptor (NMDAR) antagonist S-ketamine shifted perception toward the external mode, favoring sensory input over prior knowledge. A case-control study found that people with paranoid schizophrenia, a condition linked to NMDAR hypofunction, also spend more time in the external mode. This NMDAR-dependent shift suggests that schizophrenia symptoms may arise from recurring disconnections between perception and prior knowledge about the world.
Schizophrenia spectrum disorders (SSD) involve pervasive disturbances in how the brain processes internal bodily signals—a function called interoception. In a cross-sectional observational study, 53 people with SSD and 60 matched healthy controls completed a heartbeat counting task and EEG recordings. People with SSD showed altered subjective interoceptive awareness, including impaired regulation and negative bodily appraisal, along with elevated depersonalization. Their interoceptive accuracy was marginally lower, and their heartbeat evoked potentials were attenuated, especially during the heartbeat counting task, over centro-parietal regions. Depersonalization was the most consistent correlate of clinical severity. These findings suggest interoceptive dysfunction is a central, trait-like feature of SSD.