NEAR-INFRARED SPECTROSCOPY (NIRS) - A NEW TOOL TO STUDY HEMODYNAMIC-CHANGES DURING ACTIVATION OF BRAIN-FUNCTION IN HUMAN ADULTS

In healthy human adults, cerebral concentrations of oxygenated hemoglo bin ([HbO2]) and deoxygenated hemoglobin ([HbR]) were assessed during brain activation using near infrared spectroscopy (NIRS). Measurements were made either in the frontal cortex (n=10) during performance of c ognitive tasks or in the occipital cortex (n=6) during visual stimulat ion (flash-light exposure, picture observation). The typical findings during brain activation were an increase in [HbO2] and a decrease in [ HbR]. We demonstrate that these findings are not due to alterations in skin blood flow. NIRS is a simple bedside technique for the assessmen t of hemodynamic alterations accompanying brain activation.