| The purpose of my dissertation is to describe the development of frequency-domain near-infrared spectroscopy (FD-NIRS) into a non-invasive and safe functional brain imaging tool for clinical and research applications. FD-NIRS is a great tool for studying cerebral physiology because we can study hemodynamic processes in the brain in real-time, where data is collected multiple times per second over time periods of hours continuously. The development of FD-NIRS has been driven by the need to non-invasively explore the anatomy and physiology of the brain from the surface of the head. Since tissues are highly transparent in the near-infrared spectral region, near-infrared light can travel through tissues. The light is treated as probability distribution of photons that are traveling through highly-scattering tissues by diffusion. FD-NIRS instrumentation measures the scattering and absorption coefficients of tissues at 758 nm and 830 nm in the near-infrared spectral window. By obtaining the absorption coefficients of the brain, we can measure brain tissue oxygen saturation and cerebrovascular hemodynamics in real-time.;Monitoring brain tissue oxygen supply, demand, delivery and consumption can be achieved by quantifying the absolute values of oxy- and deoxy-hemoglobin and how these quantities change over time during rest, functional activation, pathology, and disease. My dissertation describes the development, signal analysis, validity, and clinical feasibility of FD-NIRS and how useful the information may be for general health knowledge and preventive medicine. |
