BACKGROUND AND HYPOTHESIS:Visual hallucinations (VH), a key symptom in neurodegenerative and psychiatric disorders, are associated with a more severe psychopathological profile and less favorable outcome. Neuroimaging research has revealed widespread brain regions involved in VH, echoing the updated notion that neuropsychiatric symptoms correspond more closely to interconnected brain networks than to single brain regions. However, there is still a dearth of studies examining brain network localization of VH. STUDY DESIGN:We initially identified brain structural and functional alterations specific to VH from 21 published neuroimaging studies with 418 VH and 522 non-VH individuals. By applying novel functional connectivity network mapping to large-scale discovery (n = 1113) and validation (n = 1093) resting-state functional magnetic resonance imaging datasets, we mapped these affected brain locations to 2 specific networks. STUDY RESULTS:The VH structural alteration network comprised a broadly distributed set of brain regions principally implicating the frontoparietal and dorsal attention networks. The VH functional alteration network also consisted of widely distributed brain areas predominantly involving the ventral attention and frontoparietal networks. CONCLUSIONS:Our findings may not only draw a more refined picture of the neurobiology of VH from a network perspective, but also potentially contribute to more targeted and effective treatment for VH.

Background There is a considerable overlap in clinical features and genetics between schizophrenia (SZ) and bipolar disorder (BD). Previous neuroimaging research has demonstrated common and distinct brain damage patterns between relatives (RELs) of SZ and BD patients, suggesting shared and differential genetic influences on the brain. Despite an increasing recognition that disorders localize better to distributed brain networks than individual brain regions, studies investigating network localization of genetic risk for SZ and BD are still lacking.Methods To address this gap, we initially identified brain functional and structural damage locations in SZ- and BD-RELs from 103 published studies with 2364 SZ-RELs, 864 BD-RELs, and 4114 healthy controls. By applying novel functional connectivity network mapping to large-scale discovery and validation resting-state functional MRI datasets, we mapped these affected brain locations to four disorder-susceptibility networks.Results SZ-susceptibility functional damage network primarily involved the executive control and salience networks, while its BD-counterpart principally implicated the default mode and basal ganglia networks. SZ-susceptibility structural damage network predominantly involved the auditory and default mode networks, yet its BD-counterpart mainly implicated the language and executive control networks. Although these networks showed cross-disorder inconsistencies when focusing on either imaging modality alone, the combined SZ- and BD-susceptibility brain damage networks had a substantially increased spatial similarity.Conclusions These findings may support the concept that SZ and BD represent distinct diagnostic categories from a neurobiological perspective, helping to clarify the common network substrates via which the shared genetic mechanisms underlying both disorders give rise to their overlapping clinical phenotypes.