MicroRNAs (miRNAs) are abundant in the brain and have been implicated in neurogenesis and brain disorders.However, the essential rules of miRNAs in regulation of progressive neurodegeneration have not been established.In this study, we provide evidence that mir-128a is up-regulated in the brain of Alzheimers disease (AD).We further demonstrate that this miRNA inhibits expression of the synaptotagmin Ⅰ (SYT1), which is a synaptosomal proteins deranged in neurodegenerative disorders.The findings may provide valuable clues to unravel the impaired neuronal transmission in AD brain.