Patches of Interest (POI) in surface space are comparable to volumes of interest (VOI) in volume space or regions of interest (ROI) in FMR space.
POIs can be created based on functional clusters in statistical surface maps (SMPs) or can be drawn directly on the mesh. The latter approach is for example useful if one would like to define a POI based on the cortical folding pattern of a participant.
The User's Guide of BrainVoyager describes in the section 'Drawing POIs" how to define a POI by marking a specific region of the cortical mesh.
The functional definition of POIs is similar to the functional definition of VOIs in volume space and can be invoked in the 'Advanced' tab of the 'Surface Maps' dialog after loading a statistical map (SPM):