Dorsal-ventral precuneus gradients organise large-scale networks and track consciousness level

Large-scale functional connectivity (FC) networks are typically treated as discrete neuroanatomical entities, yet their organisation in regions where multiple systems converge remains poorly understood. Here we investigate the posterior precuneus (PCu)—a key hub of the default mode network (DMN) situated at the interface with the frontoparietal control network (FPCN)—using a spatial-derivative approach that quantifies how FC changes along the PCu's dorsal–ventral axis. Across five pharmacological datasets encompassing psychedelic and anaesthetic states, we demonstrate that the spatial derivative of functional connectivity (FC) recovers canonical DMN–FPCN organization with superior anatomical specificity compared to FC alone. This functional gradient is systematically modulated by consciousness level: its overall magnitude diminishes across all altered states of consciousness (ASCs), while its spatial entropy increases under psychedelics but decreases under sedation. These effects cannot be explained by local smoothing and instead suggest that the PCu embeds a continuous, anatomically constrained transition between large-scale networks that is sensitive to global brain-state dynamics. Our findings motivate a gradient-based perspective on functional network organisation and identify a parsimonious neural signature that tracks the brain’s dynamical repertoire across diverse ASCs.