“…NIRS is specifically a measure of regional cerebral tissue oxygenation saturation, primarily reflective of venous blood (Brawanski, Faltermeier, Rothoerl, & Woertgen, 2002;Ohmae et al, 2006) and is highly sensitive to conditions that alter the flow of oxygenated blood to brain tissue, including cerebral ischemia in subarachnoid hemorrhage, cerebral vasospasm in response to cardiac surgery, hyperperfusion after carotid endarerectomy, hypoperfusion related to anesthesia, as well as to changes in cerebral oxygenation related to high altitude, carbon dioxide challenge, and transient induced hypoxia in healthy volunteers (Hadolt & Litscher, 2003;Kim et al, 2000;McCormick, Stweart, Goetting, & Balakrishnan, 1991;. As noted earlier, older adults, even if they are free of cardiovascular disease, show declining baseline levels of oxygenated CBF relative to younger adults (Bangen et al, 2009;Larsson et al, 2001).…”