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fMRI Ch 7

TermDefinition
Oxygenated Hemoglobin (Hb) Hemoglobin with attached oxygen; it is diamagnetic
Diamagnetic Having the property of a weak repulsion from a magnetic field
Deoxygenated Hemoglobin (dHb) Hemoglobin without attached oxygen; it is paramagnetic
Paramagnetic Having the property of being attracted to a magnetic field, though with less concentration of magnetic flux than ferromagnetic objects
Magnetic Susceptibility The intensity of magnetization of a substance when placed within a magnetic field
Blood-oxygenation-level dependent (BOLD) contrast The difference in signal on T2-weighted images as a function of the amount of deoxygenated hemoglobin
Autoradiography An invasive imaging technique that labels molecules using radioactive isotopes and the measures the concentration of those molecules by exposing slices of tissue to photographic emulsions
Balloon Model A model of the interaction between changes in blood flow associated with neuronal activity
Hemodynamic Response (HDR) The change in MR signal on T2 images following the local neuronal activity. The hemodynamic response results from a decrease in the amount of deoxygenated hemoglobin present within a voxel
Peak The maximal amplitude of the hemodynamic response, occurring typically about 4 to 6 s following a short-duration event
Undershoot The decrease in MR signal amplitude below baseline due to the combination of reduced blood flow and increased blood volume
Time course The change in MR signal over a series of fMRI images
Epoch A time segment extracted from a larger series of images, usually corresponding to the period in time surrounding an event of interest
Created by: dkbjornn