Which description best characterizes functional MRI?

Which description best characterizes functional MRI?

• A. An imaging technique that uses ionizing radiation to measure metabolism
• B. An imaging technique that records electrical activity on the scalp
• C. An imaging technique that maps brain activity by measuring blood flow related to oxygen use
• D. An imaging technique that only shows static brain anatomy

Answer: (C)

Functional MRI detects brain activity by tracking blood flow changes that occur with oxygen use. When a region of the brain is more active, it consumes more oxygen, and the body responds by increasing blood flow to that area. The MRI senses these shifts in the ratio of oxygenated to deoxygenated hemoglobin, producing a signal (the BOLD signal) that maps which areas are active during a task. This gives strong spatial detail about where activity happens, and it’s noninvasive because it uses magnetic fields rather than radiation. It’s not measuring electrical signals on the scalp (that would be EEG) and it isn’t limited to static brain anatomy—it shows functional changes over time, although the timing is slower due to the vascular response. So describing functional MRI as mapping brain activity by measuring blood flow related to oxygen use captures what the technique actually does.

Functional MRI detects brain activity by tracking blood flow changes that occur with oxygen use. When a region of the brain is more active, it consumes more oxygen, and the body responds by increasing blood flow to that area. The MRI senses these shifts in the ratio of oxygenated to deoxygenated hemoglobin, producing a signal (the BOLD signal) that maps which areas are active during a task. This gives strong spatial detail about where activity happens, and it’s noninvasive because it uses magnetic fields rather than radiation. It’s not measuring electrical signals on the scalp (that would be EEG) and it isn’t limited to static brain anatomy—it shows functional changes over time, although the timing is slower due to the vascular response. So describing functional MRI as mapping brain activity by measuring blood flow related to oxygen use captures what the technique actually does.