To the extent that these syndromes tend to be caused by different molecular pathologies, this selectivity is in turn a readout of particular pathogenic proteins and protein configurations that target specific neural circuit elements, in line with the molecular nexopathies paradigm [2, 3] (TDP-43 in semantic appraisal network, svPPA; AD pathology in default mode network, lvPPA; hyperphosphorylated tau in dorsal peri-Sylvian networks, nfvPPA). This evidence concerns the gene MAPT and Alzheimer disease.