Lesions causing room tilt illusion link a cerebello-cingulate brain network to verticality perception

Verticality perception is the sense of one's body orientation relative to gravity. It can be disrupted by neurological diseases or during aviation and space flight, resulting in falls and accidents. This perception is thought to arise from integration of vestibular and visual signals, yet where this multisensory computation is spatially implemented in the human brain remains unresolved. Room tilt illusion (RTI), in which the visual environment abruptly reorients relative to gravity (typically by 90° or 180°), has been proposed as a model disorder for studying verticality perception. Here, we leverage focal brain lesions (predominantly ischemic or hemorrhagic strokes) causing RTI to localize this multisensory computation. We assembled a total of 37 patients with brain lesions causing RTI from a systematic literature search and local cases across two centers. Clinical data were tabulated and lesions were analyzed using multimodal voxel- and connectome-based lesion mapping methods. Lesion findings were further tested against an independent dataset of 509 direct electrical stimulation sites associated with vestibular or non-vestibular percepts. The RTI lesions were distributed across cortical and subcortical locations, with the cerebellum representing the most frequent lesion site (49%). Despite anatomical heterogeneity, lesion connectivity converged on two hub regions: one in the posterior cerebellum and another in the mid-cingulate cortex. This pattern was robust to methodological variations, separation of RTI subtypes, and exclusion of cerebellar lesions. This pattern was also specific to RTI when compared against 185 phenotypically matched lesions from patients with milder disturbances of verticality perception and 1,110 lesions associated with 27 other neuropsychiatric syndromes. Finally, independent direct electrical stimulation data converged on both lesion-derived RTI hubs (mid-cingulate cortex: g=0.62, p<.001; posterior cerebellum: g=0.34, p=.014, 10,000 label permutations). In conclusion, anatomically diverse RTI lesions localize to a specific cerebello-cingulate network, providing an anatomical framework for verticality perception in the human brain. Our findings generate testable hypotheses for experimentally modulating or protecting verticality perception in neurological patients or pilots.