However, in PiD, tau pathology is mainly found in granular neurons in the hippocampal dentate gyrus, the hippocampal CA1 pyramidal neurons, and layer II of the frontal and temporal cortices in the form of 3R, while in PSP, CBD, and AGD it mainly presents in the form of 4R in astrocytes. The gene discussed is MAPT; the disease is argyrophilic grain disease.