Dementia with Lewy bodies (DLB) is the second cognitive neurodegenerative disease after Alzheimer’s disease (AD). DLB patients develop cognitive deficits as in AD, and one or more features of parkinsonism. At the neuropathological level, patients show α-syn aggregates called Lewy bodies (LB) which are also characteristic in Parkinson’s disease (PD). At DLB onset, LB are diffuse in the whole brain, whereas at PD onset they are more restricted to the brainstem and the substantia nigra. Only a few DLB animal models have been described. This project aims to generate and characterize new DLB mouse models. We have phenotyped a mouse model overexpressing the human α-syn (hα-syn) in neurons (SNCA model). We show that the mice develop behavioral and neuropathological frontal impairments, which seems to match the prodromal stage of DLB in humans. Based on clinical observations, we aimed to amplify SNCA mice symptoms by targeting the insular cortex with injection of hα-syn fibrils. SNCA mice did not show any worsening of the behavioral phenotype. However, we observed a great propagation of a pathological form of α-syn throughout insular cortex interconnected regions.