MAPT and tauopathy: To investigate if AP firing was impaired in the hippocampal CA1 region of FTLD-Tau mutant P301L tau transgenic mice, we first performed whole-cell patch-clamp recordings from rTg4510 and wild-type mice aged 1–2 months (an early stage of tauopathy prior to overt tau hyperphosphorylation and synaptic impairment), 4–6 months (a mid-stage with extensive tau hyperphosphorylation and impairment of synaptic activity and spatial memory) and 12–14 months (a late stage after synaptic loss and neurodegeneration have been initiated) [21, 41, 45].