In fact, some age-dependent neurodegenerative processes (such as the deposition of amyloid beta plaque and/or tau tangles in AD) may impair synaptic transmission within both the thalamus and cortex, and the process of biological aging itself may impair the function of synapses in both the thalamus and cortex (Henley and Wilkinson, 2013). This evidence concerns the gene MAPT and Alzheimer disease.