What is Functional magnetic resonance imaging?
Functional magnetic resonance imaging (fMRI) is a neuroimaging technique that detects brain activity by measuring changes in blood oxygenation. When neurons become more active, local blood flow increases, and fMRI detects this hemodynamic response.
How it works
fMRI provides excellent spatial resolution (millimeter-level precision of where activity occurs) but limited temporal resolution (the hemodynamic response peaks 4-6 seconds after neural activity). It is the most widely used tool in cognitive neuroscience for mapping brain function. fMRI has revealed the neural correlates of decision-making, emotion, memory, language, and social cognition. Limitations include susceptibility to motion artifacts, the inability to distinguish excitatory from inhibitory activity, and the indirect relationship between the blood signal and actual neural processing.
Applied example
Researchers use fMRI to show that when people consider unfair offers in the ultimatum game, the anterior insula (associated with disgust) activates more strongly before rejected offers than accepted ones, revealing the neural basis of the emotional response that drives economically ‘irrational’ rejections.
Why it matters
fMRI has transformed behavioral science by making the neural mechanisms underlying psychological processes visible, though interpreting its results requires understanding the gap between blood flow changes and neural computation.
