Combining functional magnetic resonance imaging and near infrared spectroscopy to study functional activation in the human brain

• Antragstellerin: Dr. Evgeniya Kirilina
• Fachliche Zuordnung: Automatisierungstechnik, Mechatronik, Regelungssysteme, Intelligente Technische Systeme, Robotik
• Förderung: Förderung von 2006 bis 2010
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 33237966

The aim of the present study is to develop an experimental setup together with data analysis algorithms for concurrent functional Magnetic Resonance Imaging (fMRI), and time-domain Near Infrared Spectroscopy (td-NIRS) to study the time dependence of the cerebral metabolic rate of oxygen consumption during a functional activation. As a first application of this multi-modal setup we will study the hemodynamic response in the primary and supplementary motor cortex areas in the human brain during motor task performance. fMRI and NIRS proved to be valuable modalities to investigate the functional organization of the human brain. Both techniques are sensitive to the vascular response on neuronal activity. Although they provide highly desired brain activation maps, additional information is required in order to link the vascular response to the temporal and local activation of neurons. Direct measurements of the cerebral metabolic rate of oxygen consumption (CMRO2) during neuronal activity would be an important step toward this goal. CMRO2 is linked to neuronal activity due to enhanced energy demand of the activated neurons. Therefore, CMRO2 changes are independent of the response of arterioles and veins, which delay and confound the hemodynamically based signals measured by NIRS and fMRI. Our strategy to determine CMRO2 is to obtain and combine information from MRI, in particular by Arterial Spin Labeling (ASL) and Blood Oxygen Level Dependent (BOLD) signals, and NIRS in a simultaneous experiment. ASL allows temporal measurements of the blood flow through the region of interest. In addition the concentrations of oxygenated and deoxygenated hemoglobin during neuronal activation can be obtained by NIRS. Thus the difference between inflow and outflow of oxygenated hemoglobin can be determined, reflecting the amount of oxygen metabolized in the activated region. To overcome the poor spatial resolution provided by continuous wave NIRS (cw-NIRS) we plan to run time-domain NIRS experiments and reconstruct them with the aid of MRI data. By using the information extracted from MR anatomic images and fMRI activation maps as prior knowledge, reconstruction of NIRS data can be improved.

• DFG-Verfahren: Sachbeihilfen