Functional magnetic resonance imaging (fMRI)
Seiji OgawaAnders EklundThomas Nichols
This page delivers no verdict; it presents claims and evidence with their sources. No theory in science is absolute. Method
For everyone
fMRI indirectly shows which brain regions are more active during a task by measuring changes in blood oxygenation. The BOLD signal it relies on was described in 1990 by Seiji Ogawa and colleagues. By allowing the human brain to be studied without surgery, fMRI transformed cognitive neuroscience. It has also been shown, however, that some statistical methods can give false positives and that repeated measurements in the same person can have low reliability.
For specialists
Deoxygenated haemoglobin is paramagnetic and distorts the magnetic field. Because blood flow to an active region rises more than oxygen consumption, the proportion of deoxygenated haemoglobin falls and the signal rises (BOLD). The signal tracks neural activity indirectly, with a delay of a few seconds. Since hundreds of thousands of voxels are tested in one scan, correction for multiple comparisons is essential. A common cluster-based method was reported to give false positive rates of up to 70 percent instead of the nominal 5 percent.
Claims
- The blood-oxygenation-level-dependent (BOLD) signal is an indirect but usable measure of neural activity in brain regions.[1]
Evidence
Supporting
When blood oxygen levels were changed in the rat brain, the vessel contrast in MR images changed accordingly.[1]
Challenging
Checks with real resting-state data showed that a common statistical method gives very high false positive rates, calling for some earlier findings to be re-evaluated.[2]
A meta-analysis found that task-based fMRI measures show poor reliability when repeated in the same people, limiting their use for measuring individual differences.[3]
Connections
Parent
Psychology and mindThis topic is a stop on these journeys
Sources
- Article (1990). Brain magnetic resonance imaging with contrast dependent on blood oxygenation. Proceedings of the National Academy of Sciences 87(24), 9868–9872DOI 10.1073/pnas.87.24.9868archive
- Article (2016). Cluster failure: why fMRI inferences for spatial extent have inflated false-positive rates. Proceedings of the National Academy of Sciences 113(28), 7900–7905DOI 10.1073/pnas.1602413113archive
- Article (2020). What is the test-retest reliability of common task-functional MRI measures? New empirical evidence and a meta-analysis. Psychological Science 31(7), 792–806DOI 10.1177/0956797620916786archive
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Cite this page
Athena contributors. (2026). Functional magnetic resonance imaging (fMRI). Athena: The tree of human knowledge. Retrieved November 1, 2026, from https://latifkedi.github.io/athena/en/d/fmri/
@misc{athena_fmri,
title = {Functional magnetic resonance imaging (fMRI)},
author = {{Athena contributors}},
year = {2026},
howpublished = {\url{https://latifkedi.github.io/athena/en/d/fmri/}},
note = {Athena: The tree of human knowledge. Accessed: 2026-11-01}
}Added: September 28, 2026 · Last changed: September 28, 2026 · Page history