MAPT and tauopathy: To validate these findings in neurons in vivo, in the intact mouse nervous system, we used a transgenic mouse model of tauopathy, THY-Tau22 (hereafter Tau22) mice overexpressing mutant tau protein in the brain.30 In 5- to 8-month-old Tau22 animals, phosphorylated tau could be readily detected with AT8 antibody both in the cortex and hippocampus but its levels were moderate in the majority of neurons and only a minor fraction of neurons presented with dense accumulations of phosphorylated tau protein (Figure 4a).