Researchers investigating brain activity in older people say the coordination between neuronal activity and the brain's oxygenation is altered. Non-invasive recording of the function of these neurovascular units in living humans has never been done before, but has now been achieved by using several measurement techniques coupled with novel analysis methods. The results promise a relatively simple and non-invasive method for assessing the state of the brain in healthy aging, and in neurodegenerative disorders such as Alzheimer's disease.