MAPT and Alzheimer disease: Experimental paradigm: in vitro whole cell patch clamp recordings from hippocampal CA1 pyramidal neurons; in vitro LFPs recordings from hippocampal slices.Findings: no difference in amplitude and frequency of action potentials between 3×Tg-AD and non-Tg CA1 pyramidal neurons. Overall, the young 3×Tg-AD mice showed less excitable hippocampal network activity, likely related to abnormally hyperphosphorylated tau at microtubule domain region (MDr).