This flash workshop is the 4th of 6 different others, presenting 6 different applications of the commercial 3D software Imaris, from visualization, to network description. The example chosen to explore spot-to-surface proximity analysis tools is a study in neurobiology. The BIN1 gene is a genetic risk factor strongly associated with Alzheimer's disease. In order to understand the role of the BIN1 genetic risk in the disease, our collaborators from the U1167 unit (AM.Ayral and D.Kilinc) seek to identify the number of microglial cells which are close to the amyloid plaques in APP and APPBin mice. For this, 1 mm brain sections were rendered transparent and labeled by immunostaining (nuclei: DAPI, plaques: 6E10-488, Microglia: Tremp2-550). The goal of this Flash tutorial is to understand the differences between two ways to analyse co-distribution between two markers. The classical way used to measure co-distribution is a pixel-based approach. Imaris can give access to different parameters (Pearson, Manders,…). The other way to do such analysis is a distance-based approach. With this method you have access to a proximity analysis. How far is one marker from the other? Participants will follow an analysis pipeline that uses both the spots (cells), and the surfaces (cells or other extended structures) to study their proximity. The workshop will be a hands-on-session with a computer for each attendant, working with the same datasets (3D / multiphoton images). They will follow a step by step a guiding workflow.