Hence, we decided to further explore the different binding properties/mechanisms of the second-generation tau PET tracers in AD versus in primary tauopathies such as PSP and CBD using in vitro radioligand binding in brain homogenates as well as large and small frozen brain section autoradiography, with the idea that this could also discriminate AD from other neurodegenerative diseases. Here, MAPT is linked to red-green color blindness.