MAPT and Alzheimer disease: When AD tau extracts containing Aβ are injected into mice, the ipsilateral hippocampus and parts of the overlying cortex exhibited a redistribution of Aβ along the hilus of the dentate gyrus, the outer edges of the dentate gyrus molecular layer, the hippocampal fissure, and the white matter surrounding the hippocampus and lower cortical regions (Fig. 4, B and C).