What type of information do fMRI color images primarily convey?

• A. Structural outlines only
• B. Electrical activity maps
• C. Metabolic activity and functional activation
• D. Diffusion directions

Answer: (C)

Functional MRI color images show metabolic demand related to neural activity, i.e., where and when parts of the brain become more active during a task. The color maps display the BOLD signal—changes in blood oxygenation and flow that accompany increased neural activity rather than the actual electrical signals themselves. This means the colors indicate functional activation: regions with higher metabolic demand show stronger color signals after a task or stimulus.

These images aren’t structural outlines of the brain (those come from anatomical MRI), nor do they directly map electrical activity (that’s measured by EEG/MEG). They also aren’t about diffusion directions (that’s from diffusion imaging to reveal white matter tracts). So the color-coded results specifically reflect changes in metabolic activity associated with functional activation.