We investigated network hypersynchrony at 3 weeks of age (prior to amyloid plaque deposition, neurofibrillary pathology, and cognitive impairment) in a triple transgenic mouse model of AD (3xTg-AD) that harbors mutated human APP, tau and PS1 genes (Oddo et al., 2003b). The gene discussed is PSEN1; the disease is Alzheimer disease.