Optical Methods for the Study of Brain Metabolism In Situ

From its inception, the International Society of Oxygen Transport to Tissue (ISOTT) included several core members who were intrigued by the possibility of using light to probe the metabolic state of the cerebral cortex. This 50th anniversary review will focus on optical methods (UV, Visible, NIR) used to study brain oxygen metabolism in the intact brain. Chance, Lübbers, and Jöbsis did fundamental work in the 1970s and 1980s. These investigators spearheaded the use of fluorescence of pyridine nucleotides (e.g., NADH) and flavoprotein, and visible and near-infrared spectroscopy of haemoglobin amount and saturation, as well as the mitochondrial cytochrome chain. Two of our society awards are named for these pioneers and founders. By the new millennium, their many scientific descendants (although still too few for the task at hand) have been productive and moved the field forward. Technical advances in materials, detectors, devices, and computer power have made great advances possible. Physiological theory and understanding of cell and molecular mechanisms still lag, providing fertile territory for future goals. There are at least two major directions currently that will certainly continue to illuminate brain metabolism (obvious-and well worn-pun intended). These are the burgeoning NIR instrumentation variations, and second, the tremendous potential of two-photon phosphorescence lifetime microscopy. These advances have been introduced through the years and continue to be advanced at our annual ISOTT symposia.