For almost three decades, functional magnetic resonance imaging (fMRI) has been one of the main tools in brain research. Yet a new study published in the renowned journal Nature Neuroscience fundamentally challenges the way fMRI data have so far been interpreted with regard to neuronal activity. According to the findings, there is no generally valid coupling between the oxygen content measured by MRI and neuronal activity.

Researchers at the Technical University of Munich (TUM) and the Friedrich-Alexander-University Erlangen-Nuremberg (FAU) found that an increased fMRI signal is associated with reduced brain activity in around 40 percent of cases. At the same time, they observed decreased fMRI signals in regions with elevated activity. First author Dr. Samira Epp emphasizes: “This contradicts the long-standing assumption that increased brain activity is always accompanied by an increased blood flow to meet higher oxygen demand. Since tens of thousands of fMRI studies worldwide are based on this assumption, our results could lead to opposite interpretations in many of them.”