<qa>  What is the purpose of the Jan Medical Nautilus NeuroWaveTM?The Jan Medical Nautilus NeuroWaveTM NNW is a non-invasive device designed to evaluate brain oscillation patterns or the brains pulse, generated by cardiac cycle induced intracranial blood flow. The objective of the evaluation is to determine whether the oscillation pattern is normal, whether it has been disrupted, and, if disrupted, what particular disruption pattern is evident. Various cerebral pathologies studied to date with the NNW demonstrate distinct disruption patterns. These pathologies include vasospasm, concussion and arterio-venous malformation AVM. The objective of this study is to evaluate the brain oscillation patterns from subjects with MCI, Frontotemporal dementia, AD and from a small cohort of age matched normal controls and determine whether they exhibit pattern disruption and, if so, to quantify and categorize the distinct disruption patterns. How the Nautilus NeuroWave accomplishes this is explained later in the device description section of the protocol. 