Jumping in the discussion a bit late, sorry: a lesion would alter the head model/gain vectors of sources if its conductivity parameters are different from surrounding tissues ; for instance if this is a resected portion of cortex, then its conductivity is that of CSF. A FEM/BEM model can explicitly take these aspects into account in the head model, again, if the region in question is properly delineated. See this recent paper: https://pubmed.ncbi.nlm.nih.gov/35781078/
1 Like