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Blood-oxygenation-level–dependent imaging, or BOLD-contrast imaging, is a method used in functional magnetic resonance imaging (fMRI) to observe different areas of the brain or other organs, which are found to be active at any given time.
The hemodynamic response is the basis for the BOLD (blood oxygen level dependent) contrast in fMRI. [5] The hemodynamic response occurs within seconds of the presented stimuli, but it is essential to space out the events in order to ensure that the response being measured is from the event that was presented and not from a prior event.
The primary form of fMRI uses the blood-oxygen-level dependent (BOLD) contrast, [4] discovered by Seiji Ogawa in 1990. This is a type of specialized brain and body scan used to map neural activity in the brain or spinal cord of humans or other animals by imaging the change in blood flow ( hemodynamic response ) related to energy use by brain ...
Resting state fMRI (rs-fMRI or R-fMRI), also referred to as task-independent fMRI or task-free fMRI, is a method of functional magnetic resonance imaging (fMRI) that is used in brain mapping to evaluate regional interactions that occur in a resting or task-negative state, when an explicit task is not being performed.
In single-voxel fMRS the selection of the volume of interest (VOI) is often done by running a functional magnetic resonance imaging (fMRI) study prior to fMRS to localize the brain region activated by the task. Single-voxel spectroscopy requires shorter acquisition times; therefore it is more suitable for fMRS studies where high temporal ...
Amplitude of Low Frequency Fluctuations (ALFF) and fractional Amplitude of Low Frequency Fluctuations (f/ALFF) are neuroimaging methods used to measure spontaneous fluctuations in BOLD-fMRI signal intensity for a given region in the resting brain. Electrophysiological studies suggest that low-frequency oscillations arise from spontaneous ...
There are different fMRI techniques that can pick up a functional signal corresponding to changes in each of the previously mentioned components of the haemodynamic response. The most common functional imaging signal is the blood-oxygen-level dependent signal (BOLD), which primarily corresponds to the concentration of deoxyhemoglobin. [13]
In addition, the BOLD signal at white matter and ventricles can be used to characterize potential motion and physiological noise sources, and the combined effect of these and other noise sources can be removed from the functional data to improve the robustness of functional connectivity measures. [6]