A recent study by Epp et al. uses advanced, quantitative functional MRI measures to demonstrate that the ‘canonical’ interpretation of blood-oxygenation-level-dependent (BOLD) functional MRI (fMRI) — that increases and decreases in brain activation are accompanied by corresponding changes in blood flow and oxygen metabolism — does not strictly hold across the human brain. Although the authors provided a balanced interpretation, this has been viewed by others as undermining fMRI.