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Blood-oxygen-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 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 ...
Within fMRI methodology, there are two different ways that are typically employed to present stimuli. One method is a block related design, in which two or more different conditions are alternated in order to determine the differences between the two conditions, or a control may be included in the presentation occurring between the two conditions.
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.
This finding has an important implication for the interpretation of BOLD fMRI data where this high baseline activity is generally ignored and response to the task is shown as independent of the baseline activity. 13 C MRS studies indicate that this approach can misjudge and even completely miss the brain activity induced by the task. [37]
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]
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BOLD-contrast is a naturally occurring process in the body so fMRI is often preferred over imaging methods that require radioactive markers to produce similar imaging. [33] A concern in the use of fMRI is its use in individuals with medical implants or devices and metallic items in the body.