MAPT and memory impairment: Memory impairment, Aβ aggregation, tau hyper-phosphorylation, neuroinflammation, dysregulation of insulin signaling, and the downregulation of miR-26a, miR-124, miR-29a, miR-181b, miR-125b, miR-132, and miR-146a are observed in the hippocampus of rats exposed to Aβ oligomers.