Visual hallucination (VH) is the most common psychosis in Parkinson's disease (PD) 1,2 , and is present in 25-50% of PD patients 1,3 . Visual hallucination in PD patients is an important risk factor in terms of nursing home placement, poor quality of life, and mortality 4 . Neuroimaging studies suggested that brain regions involved in higher-order visual processing, ventral or dorsal pathways, were associated with VH in PD patients [5][6][7][8][9] . Pathologic study in Lewy body (LB) disease reported a striking association between the distribution of temporal lobe LB and VH 10 . Visual hallucination in PD seems to be associated with dysfunction of higher-order visual pathways, specifically, the occipitotemporal pathway (the ventral visual pathway). We investigated the regional cerebral glucose metabolism related to VH in PD patients to identify brain regions, focusing on the ventral visual pathway.Previous studies excluded patients with cognitive impairment (CI), an important VH-related nonmotor symptom in PD 8 , Compared to the patients with PDNVH, PD-VHNCI patients showed glucose hypometabolism in the inferior and middle temporal cortices, fusiform gyri, and frontal areas, suggesting the involvement of the ventral visual pathway. Compared to the patients with PDNVH, PD-VHCI patients showed glucose hypometabolism in the temporoparietal association cortices with scattered frontal areas. Conclusion: Dysfunction of ventral visual pathway involving the temporal lobe may play a key role in VH development in PD patients. The evolving distribution from the ventral visual pathway to more extensive posterior cortices in PD-VHCI patients suggests that VH may be a prodromal symptom occurring prior to CI in PD patients. RĂ©sultats : Les patients atteints de MP-HVNDC avaient un hypomĂ©tabolisme du glucose dans le cortex temporal infĂ©rieur et moyen, la circonvolution occipito-temporale latĂ©rale et les zones frontales par rapport aux patients atteints de MP-NHV, ce qui indique que la voie visuelle ventrale pourrait ĂȘtre impliquĂ©e. Les patients atteints de MP-HVDC avaient un hypomĂ©tabolisme du glucose dans les cortex associatifs temporo-pariĂ©taux ainsi que dans des zones frontales dispersĂ©es par rapport aux patients atteints de MP-NHV. Conclusion : Une dysfonction de la voie visuelle ventrale impliquant le lobe temporal pourrait jouer un rĂŽle clĂ© dans l'apparition des HV chez les patients atteints de la MP. La distribution Ă©voluant de la voie visuelle ventrale Ă des zones plus larges du cortex postĂ©rieur chez les patients atteints de MP-HVDC indique que les HV pourraient constituer un symptĂŽme avant-coureur d'un DC chez les patients atteints de la MP.