A Under basal conditions, Tau protein is involved in the maturation of newborn granule neurons in the DG. In the absence of Tau, newborn neuron dendritic arborization is transiently altered and PSD formation is impaired (decreased PSD density and area were found in the distal dendrites).B Acute stress decreased the survival of immature 1-week-old newborn granule neurons, an effect that is less pronounced in Tau-/- animals as compared to WT. Furthermore, acute stress also impairs dendritic branching and reduces PSD density and MFT area in 8-week-old fully mature newborn neurons of WT animals. In contrast, these effects are not observed in Tau-/- mice.C EE increases 8-week-old mature newborn neuron survival, dendritic branching, MFT area and PSD density in the proximal dendrites, and decreases PSD area in the distal dendrites of WT neurons. However, these effects are less pronounced or even inexistent in the absence of Tau. Actually, EE further reduces the density and area of the PSDs in Tau-/- distal dendrites. 